Sample records for defects mechanical behavior

  1. Impact of substrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN grown by molecular beam epitaxy

    E-Print Network [OSTI]

    Armstrong, A; Poblenz, C; Green, D S; Mishra, U K; Speck, J S; Ringel, S A

    2006-01-01T23:59:59.000Z

    GaN grown by molecular beam epitaxy and codoped with carbon and silicon were investigated for substratesubstrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN

  2. Effect of point and grain boundary defects on the mechanical behavior of monolayer MoS{sub 2} under tension via atomistic simulations

    SciTech Connect (OSTI)

    Dang, Khanh Q. [Department of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Spearot, Douglas E., E-mail: dspearot@uark.edu [Department of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2014-07-07T23:59:59.000Z

    Atomistic simulation is used to study the structure and energy of defects in monolayer MoS{sub 2} and the role of defects on the mechanical properties of monolayer MoS{sub 2}. First, energy minimization is used to study the structure and energy of monosulfur vacancies positioned within the bottom S layer of the MoS{sub 2} lattice, and 60° symmetric tilt grain boundaries along the zigzag and armchair directions, with comparison to experimental observations and density functional theory calculations. Second, molecular dynamics simulations are used to subject suspended defect-containing MoS{sub 2} membranes to a state of multiaxial tension. A phase transformation is observed in the defect-containing membranes, similar to prior work in the literature. For monolayer MoS{sub 2} membranes with point defects, groups of monosulfur vacancies promote stress-concentration points, allowing failure to initiate away from the center of the membrane. For monolayer MoS{sub 2} membranes with grain boundaries, failure initiates at the grain boundary and it is found that the breaking force for the membrane is independent of grain boundary energy.

  3. Defect induced plasticity and failure mechanism of boron nitride nanotubes under tension

    SciTech Connect (OSTI)

    Anoop Krishnan, N. M., E-mail: anoopnm@civil.iisc.ernet.in; Ghosh, Debraj [Indian Institute of Science, Bangalore 560012 (India)

    2014-07-28T23:59:59.000Z

    The effects of Stone-Wales (SW) and vacancy defects on the failure behavior of boron nitride nanotubes (BNNTs) under tension are investigated using molecular dynamics simulations. The Tersoff-Brenner potential is used to model the atomic interaction and the temperature is maintained close to 300?K. The effect of a SW defect is studied by determining the failure strength and failure mechanism of nanotubes with different radii. In the case of a vacancy defect, the effect of an N-vacancy and a B-vacancy is studied separately. Nanotubes with different chiralities but similar diameter is considered first to evaluate the chirality dependence. The variation of failure strength with the radius is then studied by considering nanotubes of different diameters but same chirality. It is observed that the armchair BNNTs are extremely sensitive to defects, whereas the zigzag configurations are the least sensitive. In the case of pristine BNNTs, both armchair and zigzag nanotubes undergo brittle failure, whereas in the case of defective BNNTs, only the zigzag ones undergo brittle failure. An interesting defect induced plastic behavior is observed in defective armchair BNNTs. For this nanotube, the presence of a defect triggers mechanical relaxation by bond breaking along the closest zigzag helical path, with the defect as the nucleus. This mechanism results in a plastic failure.

  4. Mechanical Behavior of Indium Nanostructures

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  5. Mechanical Behavior of Indium Nanostructures

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  6. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  7. Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

    SciTech Connect (OSTI)

    Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI); Sepulveda-Alancastro, Nelson (University of Puerto Rico, Mayaguez, PR)

    2007-01-01T23:59:59.000Z

    Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detailed experimental study of internal dissipation in micro- and nanomechanical oscillators fabricated from amorphous and crystalline diamond materials, atomistic modeling of dissipation in amorphous, defect-free, and defect-containing crystalline silicon, and experimental work on the properties of one-dimensional and two-dimensional coupled mechanical oscillator arrays. We have identified that internal dissipation in most micro- and nanoscale oscillators is limited by defect relaxation processes, with large differences in the nature of the defects as the local order of the material ranges from amorphous to crystalline. Atomistic simulations also showed a dominant role of defect relaxation processes in controlling internal dissipation. Our studies of one-dimensional and two-dimensional coupled oscillator arrays revealed that it is possible to create mechanical systems that should be ideal for the study of non-linear dynamics and localization.

  8. Influence of defects on thermal and mechanical properties of metals

    E-Print Network [OSTI]

    Kamani, Sandeep Kumar

    2009-05-15T23:59:59.000Z

    SDen ..................................... 33 13 Copper with 8 interstitials at 1600K ....................................................... 34 14 Temperature Vs time for copper without defects at 1360K .................... 39 15 Potential energy Vs time for copper without defects... at 1360K .............. 40 16 Total energy Vs time for copper without defects at 1360K .................... 40 17 Average volume Vs temperature for pure copper without defects .......... 41 18 Total energy Vs temperature for copper without defects...

  9. Proceedings of NAMRI/SME, Vol. 41, 2013 Removal Mechanism and Defect Characterization for Glass-

    E-Print Network [OSTI]

    Yao, Y. Lawrence

    Proceedings of NAMRI/SME, Vol. 41, 2013 Removal Mechanism and Defect Characterization for Glass of NAMRI/SME, Vol. 41, 2013 f

  10. Influence of oriented topological defects on the mechanical properties of carbon nanotube heterojunctions

    SciTech Connect (OSTI)

    Lee, We-Jay [National Center for High-Performance Computing; Chang, Jee-Gong [National Center for High-Performance Computing; Yang, An-Cheng [National Center for High-Performance Computing; Wang, Yeng-Tseng [National Center for High-Performance Computing; Su, Wan-Sheng [National Center for High-Performance Computing; Wang, Cai-Zhuang [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory

    2013-10-10T23:59:59.000Z

    The mechanical properties of finite-length (5,0)/(8,0) single-walled carbon nanotube (SWCNT) heterojunctions with manipulated topological defects are investigated using molecular dynamics simulation calculations. The results show that the mechanical properties and deformation behavior of SWCNT heterojunctions are mainly affected not only by the diameter of the thinner segment of the SWCNT heterojunction but also by the orientation of the heptagon-heptagon (7-7) pair in the junction region. Moreover, the orientation of the 7-7 pair strongly affects those properties in the compression loading than those in tensile loading. Finally, it is found that the location of buckling deformation in the heterojunctions is dependent on the orientation of the 7-7 pair in the compression.

  11. Improving Cooling performance of the mechanical resonator with the two-level-system defects

    E-Print Network [OSTI]

    Tian Chen; Xiang-Bin Wang

    2014-06-03T23:59:59.000Z

    We study cooling performance of a realistic mechanical resonator containing defects. The normal cooling method through an optomechanical system does not work efficiently due to those defects. We show by employing periodical $\\sigma_z$ pulses, we can eliminate the interaction between defects and their surrounded heat baths up to the first order of time. Compared with the cooling performance of no $\\sigma_z$ pulses case, much better cooling results are obtained. Moreover, this pulse sequence has an ability to improve the cooling performance of the resonator with different defects energy gaps and different defects damping rates.

  12. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  13. Defect formation beyond Kibble-Zurek mechanism and holography

    E-Print Network [OSTI]

    Paul M. Chesler; Antonio M. Garcia-Garcia; Hong Liu

    2015-06-23T23:59:59.000Z

    We study the dynamic after a smooth quench across a continuous transition from the disordered phase to the ordered phase. Based on scaling ideas, linear response and the spectrum of unstable modes, we develop a theoretical framework, valid for any second order phase transition, for the early-time evolution of the condensate in the broken phase. Our analysis unveils a novel period of non-adiabatic evolution after the system passes through the phase transition, where a parametrically large amount of coarsening occurs before a well-defined condensate forms. Our formalism predicts a rate of defect formation parametrically smaller than the Kibble-Zurek prediction and yields a criterion for the break-down of Kibble-Zurek scaling for sufficiently fast quenches. We numerically test our formalism for a thermal quench in a 2 + 1 dimensional holographic superfluid. These findings, of direct relevance in a broad range of fields including cold atom, condensed matter, statistical mechanism and cosmology, are an important step towards a more quantitative understanding of dynamical phase transitions.

  14. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  15. Characterizing the cracking behavior of hard alpha defects in rotor grade Ti-6-4 alloy

    SciTech Connect (OSTI)

    McKeighan, P.C.; Perocchi, L.C.; Nicholls, A.E.; McClung, R.C.

    1999-07-01T23:59:59.000Z

    A program sponsored by the FAA is currently underway to develop predictive tools utilizing state-of-the-art damage tolerance and probabilistic methodologies that can be used in the life management of high energy rotors. The program is focusing on fatigue crack nucleation and growth from anomalies in titanium alloys known as hard alpha, an inclusion-like feature that can occur during the melting process. In the work detailed in this paper, two sizes of synthetic hard alpha defects are created in Ti-6Al-4V and subjected to static and fatigue loading. In addition, two different geometry anomalies are considered: one intersecting the surface of the specimen and another embedded internally. A number of crack detection transducers are used and shown to compare well to results from visual inspections on the surface defect specimens. These surface specimens tend to exhibit defect cracking at relatively low stress levels, typically on the order of 5--10 ksi. Although it appeared from the crack detection transducer that little or no cracking occurred in the interior anomaly specimens given an applied static stress of 100 ksi, subsequent metallographic sectioning demonstrated more extensive cracking and damage. The observed cracking behavior indicates that the diffusion zone may play an important role in the structural integrity of the hard alpha anomalies.

  16. Behavior analysis and mechanism: One is not the other

    E-Print Network [OSTI]

    Morris, Edward K.

    1993-01-01T23:59:59.000Z

    Behavior analysts have been called mechanists, and behavior analysis is said to be mechanistic, that is, aligned with the philosophy of mechanism. What this means is analyzed by (1) examining standard and specialized ...

  17. Characterization of Thermo-Mechanical Behaviors of Advanced High...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Thermo-Mechanical Behaviors of Advanced High Strength Steels (AHSS) Presenter: Mark Smith Principal Investigator: Xin Sun Pacific Northwest National Laboratory Principal...

  18. Characterization of Thermo-Mechanical Behaviors of Advanced High...

    Energy Savers [EERE]

    "Mega" Merit Review 2008 on February 25, 2008 in Bethesda, Maryland. merit08smith7.pdf More Documents & Publications Characterization of Thermo-Mechanical Behaviors of...

  19. A study of the mechanism of laser welding defects in low thermal expansion superalloy GH909

    SciTech Connect (OSTI)

    Yan, Fei; Wang, Chunming, E-mail: yanxiangfei225@163.com; Wang, Yajun; Hu, Xiyuan; Wang, Tianjiao; Li, Jianmin; Li, Guozhu

    2013-04-15T23:59:59.000Z

    In this paper, we describe experimental laser welding of low-thermal-expansion superalloy GH909. The main welding defects of GH909 by laser in the weld are liquation cracks and porosities, including hydrogen and carbon monoxide porosity. The forming mechanism of laser welding defects was investigated. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum, X-ray diffractometer and other methodologies. The results demonstrated that porosities appearing in the central weld were related to incomplete removal of oxide film on the surface of the welding samples. The porosities produced by these bubbles were formed as a result of residual hydrogen or oxygenium in the weld. These elements failed to escape from the weld since laser welding has both a rapid welding speed and cooling rate. The emerging crack in the heat affected zone is a liquation crack and extends along the grain boundary as a result of composition segregation. Laves–Ni{sub 2}Ti phase with low melting point is a harmful phase, and the stress causes grain boundaries to liquefy, migrate and even crack. Removing the oxides on the surface of the samples before welding and carefully controlling technological parameters can reduce welding defects and improve formation of the GH909 alloy weld. - Highlights: ? It is a new process for the forming of GH909 alloy via laser welding. ? The forming mechanism of laser welding defects in GH909 has been studied. ? It may be a means to improve the efficiency of aircraft engine production.

  20. Nonradiative coherent carrier captures and defect reaction at deep-level defects via phonon-kick mechanism

    SciTech Connect (OSTI)

    Wakita, Masaki; Suzuki, Kei; Shinozuka, Yuzo [Faculty of Systems Engineering, Wakayama University, 930 Sakaedani, Wakayama 640-8510 (Japan)

    2014-02-21T23:59:59.000Z

    We simulated the time evolution of electron-lattice coupling mode, and a series of nonradiative carrier captures by a deep-level defect in a semiconductor. For lattice relaxation energy of the order of the band gap, a series of coherent (athermal) electron and hole captures by a defect is possible for high carrier densities, which results in an inflation in the induced lattice vibration, which in turn enhances a defect reaction.

  1. Graphene flakes with defective edge terminations: Universal and topological aspects, and one-dimensional quantum behavior

    E-Print Network [OSTI]

    Igor Romanovsky; Constantine Yannouleas; Uzi Landman

    2012-10-17T23:59:59.000Z

    Systematic tight-binding investigations of the electronic spectra (as a function of the magnetic field) are presented for trigonal graphene nanoflakes with reconstructed zigzag edges, where a succession of pentagons and heptagons, that is 5-7 defects, replaces the hexagons at the zigzag edge. For nanoflakes with such reczag defective edges, emphasis is placed on topological aspects and connections underlying the patterns dominating these spectra. The electronic spectra of trigonal graphene nanoflakes with reczag edge terminations exhibit certain unique features, in addition to those that are well known to appear for graphene dots with zigzag edge termination. These unique features include breaking of the particle-hole symmetry, and they are associated with nonlinear dispersion of the energy as a function of momentum, which may be interpreted as nonrelativistic behavior. The general topological features shared with the zigzag flakes include the appearance of energy gaps at zero and low magnetic fields due to finite size, the formation of relativistic Landau levels at high magnetic fields, and the presence between the Landau levels of edge states (the socalled Halperin states) associated with the integer quantum Hall effect. Topological regimes, unique to the reczag nanoflakes, appear within a stripe of negative energies E_b < E < 0, and along a separate feature forming a constant-energy line outside this stripe. The lower bound (E_b) specifying the energy stripe is independent of size. A main finding concerns the limited applicability of the continuous Dirac-Weyl equation, since the latter does not reproduce the special reczag features. (See also the extended abstract in the paper.)

  2. Characterization of Thermo-Mechanical Behaviors of Advanced High...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. lm25smith.pdf More Documents & Publications Characterization of Thermo-Mechanical Behaviors of...

  3. Mechanical behavior of dip-brazed aluminum sandwich panels

    E-Print Network [OSTI]

    Hohmann, Brian P. (Brian Patrick)

    2007-01-01T23:59:59.000Z

    An experimental study was carried out to determine the mechanical behavior of sandwich panels containing cellular cores of varying shape. Compression and four point bend tests were performed on sandwich panels with square ...

  4. Nanostructure stabilization and mechanical behavior of binary nanocrystalline alloys

    E-Print Network [OSTI]

    Trelewicz, Jason R

    2009-01-01T23:59:59.000Z

    The unique mechanical behavior of nanocrystalline metals has become of great interest in recent years, owing to both their remarkable strength and the emergence of new deformation physics at the nanoscale. Of particular ...

  5. Thermo-mechanical Behavior of Lithium-ion Battery Electrodes

    E-Print Network [OSTI]

    An, Kai

    2013-11-25T23:59:59.000Z

    THERMO-MECHANICAL BEHAVIOR OF LITHIUM-ION BATTERY ELECTRODES A Thesis by KAI AN Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree... on the thermo-mechanical behavior of lithium ion battery electrodes. It presents a single particle model of random lattice spring elements coupled with solid phase Li-ion diffusion under active temperature effects. The thermal features are realized by solving...

  6. Mechanical behavior of elastic rods under constraint

    E-Print Network [OSTI]

    Miller, James Thomas, Ph. D. Massachusetts Institute of Technology

    2014-01-01T23:59:59.000Z

    We present the results of an experimental investigation of the mechanics of thin elastic rods under a variety of loading conditions. Four scenarios are explored, with increasing complexity: i) the shape of a naturally ...

  7. Quantum Defects and the Long-Term Behavior of Radial Rydberg Wave Packets

    E-Print Network [OSTI]

    Robert Bluhm; Alan Kostelecky

    1994-10-19T23:59:59.000Z

    We show that a theoretical description of radial Rydberg wave packets in alkali-metal atoms based solely on hydrogenic wave functions and energies is insufficient to explain data that could be obtained in pump-probe experiments with current technology. The modifications to long-term revival times induced by quantum defects cannot be obtained by direct scaling of the hydrogenic results. Moreover, the effects of laser detuning and quantum defects are different. An alternative approach providing analytical predictions using supersymmetry-based quantum-defect theory is presented.

  8. Graphene flakes with defective edge terminations: Universal and topological aspects, and one-dimensional quantum behavior

    E-Print Network [OSTI]

    Yannouleas, Constantine

    Graphene flakes with defective edge terminations: Universal and topological aspects, and one graphene nanoflakes with reconstructed zigzag edges, where a succes- sion of pentagons and heptagons these spectra. The electronic spectra of trigonal graphene nanoflakes with reczag edge terminations exhibit

  9. Dynamic behavior of Ni80Fe20 nanowires with controlled defects V. E. Demidov,2

    E-Print Network [OSTI]

    Demokritov, S.O.

    . Cottam,3 S. O. Demokritov,2,4 and A. O. Adeyeye1,a) 1 Information Storage Materials Laboratory due to their potential applica- tion for microwave devices1 and domain wall logic devices.2 Coupled the studies for the dynamic properties of NWs assume that there are no defects on the nanostructures. However

  10. Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.

    SciTech Connect (OSTI)

    Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur; Siegal, Michael P.; Li, Qiming; Jones, Reese E.; Westover, Tyler; Wang, George T.; Zhou, Xiao Wang; Talin, Albert Alec; Bogart, Katherine Huderle Andersen; Harris, C. Thomas; Huang, Jian Yu

    2010-09-01T23:59:59.000Z

    We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such as ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in concert with sophisticated molecular-dynamics calculations of surface and defect-mediated NW thermal transport. This proposal seeks to elucidate long standing material science questions for GaN while addressing issues critical to realizing reliable GaN NW devices.

  11. Annealing behaviors of vacancy-type defects near interfaces between metal contacts and GaN probed using a monoenergetic positron beam

    SciTech Connect (OSTI)

    Uedono, Akira, E-mail: uedono.akira.gb@u.tsukuba.ac.jp; Yoshihara, Nakaaki [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Fujishima, Tatsuya; Piedra, Daniel; Palacios, Tomás [Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Ishibashi, Shoji [Nanosystem Research Institute “RICS,” National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Sumiya, Masatomo [Wide Bandgap Material Group, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Laboutin, Oleg; Johnson, Wayne [IQE, 200 John Hancock Road, Taunton, Massachusetts 01581 (United States)

    2014-08-04T23:59:59.000Z

    Vacancy-type defects near interfaces between metal contacts and GaN grown on Si substrates by metal organic chemical vapor deposition have been studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation for Ti-deposited GaN showed that optically active vacancy-type defects were introduced below the Ti/GaN interface after annealing at 800?°C. Charge transition of those defects due to electron capture was observed and was found to correlate with a yellow band in the photoluminescence spectrum. The major defect species was identified as vacancy clusters such as three to five Ga-vacancies coupled with multiple nitrogen-vacancies. The annealing behaviors of vacancy-type defects in Ti-, Ni-, and Pt-deposited GaN were also examined.

  12. Raman scattering from defects in GaN: The question of vibrational or electronic scattering mechanism

    E-Print Network [OSTI]

    Nabben, Reinhard

    Raman scattering from defects in GaN: The question of vibrational or electronic scattering on defects in GaN, which appear in the Raman spectra as sharp and intense lines in the low-energy region from into the GaN material. S0163-1829 98 00344-0 I. INTRODUCTION Low-temperature Raman spectra of GaN films grown

  13. Corrosion and mechanical behavior of materials for coal gasification applications

    SciTech Connect (OSTI)

    Natesan, K.

    1980-05-01T23:59:59.000Z

    A state-of-the-art review is presented on the corrosion and mechanical behavior of materials at elevated temperatures in coal-gasification environments. The gas atmosphere in coal-conversion processes are, in general, complex mixtures which contain sulfur-bearing components (H/sub 2/S, SO/sub 2/, and COS) as well as oxidants (CO/sub 2//CO and H/sub 2/O/H/sub 2/). The information developed over the last five years clearly shows sulfidation to be the major mode of material degradation in these environments. The corrosion behavior of structural materials in complex gas environments is examined to evaluate the interrelationships between gas chemistry, alloy chemistry, temperature, and pressure. Thermodynamic aspects of high-temperature corrosion processes that pertain to coal conversion are discussed, and kinetic data are used to compare the behavior of different commercial materials of interest. The influence of complex gas environments on the mechanical properties such as tensile, stress-rupture, and impact on selected alloys is presented. The data have been analyzed, wherever possible, to examine the role of environment on the property variation. The results from ongoing programs on char effects on corrosion and on alloy protection via coatings, cladding, and weld overlay are presented. Areas of additional research with particular emphasis on the development of a better understanding of corrosion processes in complex environments and on alloy design for improved corrosion resistance are discussed. 54 references, 65 figures, 24 tables.

  14. Spatially Resolved Polarization Switching near a Planar Defect by Design: Mesoscopic Mechanisms at Tilt Grain Boundary in Bismuth Ferrite

    SciTech Connect (OSTI)

    Rodriguez, Brian J [ORNL; Choudhury, S [Pennsylvania State University; Chu, Y. H. [University of California, Berkeley; Bhattacharyya, Abishek [Lehigh University, Bethlehem, PA; Jesse, Stephen [ORNL; Seal, Katyayani [ORNL; Baddorf, Arthur P [ORNL; Ramesh, R. [University of California, Berkeley; Chen, Long-Qing [Pennsylvania State University; Kalinin, Sergei V [ORNL

    2009-01-01T23:59:59.000Z

    The effect of microstructure on ferroelectric domain nucleation in epitaxial bismuth ferrite was probed at a single atomically-defined defect: an artificially fabricated model bicrystal grain boundary (GB). Switching Spectroscopy Piezoresponse Force Microscopy is used to map the variation of local hysteresis loops at the grain boundary and its immediate vicinity. We found the influence of the GB on nucleation to be relatively weak, resulting in a slight shift of the negative nucleation bias to higher (negative) voltages. The mesoscopic mechanisms of grain boundary effect on local polarization switching are studied in detail using phase field modeling, elucidating the complex mechanisms governed by the interplay between ferroelectric and ferroelastic wall energies, depolarization fields, and interface charge. The combination of phase field modeling and SS-PFM allows quantitative analysis of mesoscopic mechanisms for polarization switching, and hence suggests a route for optimizing materials properties through microstructure optimization.

  15. Overexpressed of RAD51 suppresses recombination defects: a possible mechanism to reverse genomic instability

    SciTech Connect (OSTI)

    Schild, David; Wiese, Claudia

    2009-10-15T23:59:59.000Z

    RAD51, a key protein in the homologous recombinational DNA repair (HRR) pathway, is the major strand-transferase required for mitotic recombination. An important early step in HRR is the formation of single-stranded DNA (ss-DNA) coated by RPA (a ss-DNA binding protein). Displacement of RPA by RAD51 is highly regulated and facilitated by a number of different proteins known as the 'recombination mediators'. To assist these recombination mediators, a second group of proteins also is required and we are defining these proteins here as 'recombination co-mediators'. Defects in either recombination mediators or comediators, including BRCA1 and BRCA2, lead to impaired HRR that can genetically be complemented for (i.e. suppressed) by overexpression of RAD51. Defects in HRR have long been known to contribute to genomic instability leading to tumor development. Since genomic instability also slows cell growth, precancerous cells presumably require genomic restabilization to gain a growth advantage. RAD51 is overexpressed in many tumors, and therefore, we hypothesize that the complementing ability of elevated levels of RAD51 in tumors with initial HRR defects limits genomic instability during carcinogenic progression. Of particular interest, this model may also help explain the high frequency of TP53 mutations in human cancers, since wild-type p53 represses RAD51.

  16. On the mechanism of acceleration behavior of plasma bullet

    SciTech Connect (OSTI)

    Wu, S.; Lu, X., E-mail: luxinpei@hotmail.com; Pan, Y. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2014-07-15T23:59:59.000Z

    Two special experiments are designed to study the mechanism of the acceleration behavior of a plasma bullet when it exits a nozzle. First, a T-shape device is used to simulate the air diffusion when a plasma plume exits the nozzle. It is found that adding just 1% of N{sub 2}, O{sub 2}, or air to the main working gas He results in the acceleration of the plasma bullet. Second, materials of different permittivity are added to the left part of the outside of the tube. The experimental results show that the plasma bullet accelerates at the moment when it enters into the right part of the tube where there is no extra material on the outside of the tube. These two experiments confirm that the acceleration behavior of the plasma bullet when it exits the nozzle is due to the air diffusion, hence Penning ionization, and the permittivity change when the bullet exits the nozzle, for example, from a tube with high permittivity to air with low permittivity. Besides, electric field measurements show that the electric field in the bullet head increases when the plasma bullet accelerates. This confirms the electric field driven nature of the plasma bullet propagation.

  17. Deployment Mechanism Design with Behavioral Modeling Based on Pro/Engineer Motion Skeleton

    E-Print Network [OSTI]

    kind of motion mechanisms, is often used to stretch out solar panels or antennas in spacecraftDeployment Mechanism Design with Behavioral Modeling Based on Pro/Engineer Motion Skeleton Chao.com.cn Keywords: Deployment mechanism, Motion skeleton, Behavioral modeling, Feasibility analysis Abstract

  18. Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling

    SciTech Connect (OSTI)

    Eric Wachsman; Keith L. Duncan

    2006-09-30T23:59:59.000Z

    This research was focused on two distinct but related issues. The first issue concerned using defect modeling to understand the relationship between point defect concentration and the electrochemical, thermo-chemical and mechano-chemical properties of typical solid oxide fuel cell (SOFC) materials. The second concerned developing relationships between the microstructural features of SOFC materials and their electrochemical performance. To understand the role point defects play in ceramics, a coherent analytical framework was used to develop expressions for the dependence of thermal expansion and elastic modulus on point defect concentration in ceramics. These models, collectively termed the continuum-level electrochemical model (CLEM), were validated through fits to experimental data from electrical conductivity, I-V characteristics, elastic modulus and thermo-chemical expansion experiments for (nominally pure) ceria, gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) with consistently good fits. The same values for the material constants were used in all of the fits, further validating our approach. As predicted by the continuum-level electrochemical model, the results reveal that the concentration of defects has a significant effect on the physical properties of ceramic materials and related devices. Specifically, for pure ceria and GDC, the elastic modulus decreased while the chemical expansion increased considerably in low partial pressures of oxygen. Conversely, the physical properties of YSZ remained insensitive to changes in oxygen partial pressure within the studied range. Again, the findings concurred exactly with the predictions of our analytical model. Indeed, further analysis of the results suggests that an increase in the point defect content weakens the attractive forces between atoms in fluorite-structured oxides. The reduction treatment effects on the flexural strength and the fracture toughness of pure ceria were also evaluated at room temperature. The results reveal that the flexural strength decreases significantly after heat treatment in very low oxygen partial pressure environments; however, in contrast, fracture toughness is increased by 30-40% when the oxygen partial pressure was decreased to 10{sup -20} to 10{sup -22} atm range. Fractographic studies show that microcracks developed at 800 oC upon hydrogen reduction are responsible for the decreased strength. To understand the role of microstructure on electrochemical performance, electrical impedance spectra from symmetric LSM/YSZ/LSM cells was de-convoluted to obtain the key electrochemical components of electrode performance, namely charge transfer resistance, surface diffusion of reactive species and bulk gas diffusion through the electrode pores. These properties were then related to microstructural features, such as triple-phase boundary length and tortuosity. From these experiments we found that the impedance due to oxygen adsorption obeys a power law with pore surface area, while the impedance due to charge transfer is found to obey a power-law with respect to triple phase boundary length. A model based on kinetic theory explaining the power-law relationships observed was then developed. Finally, during our EIS work on the symmetric LSM/YSZ/LSM cells a technique was developed to improve the quality of high-frequency impedance data and their subsequent de-convolution.

  19. Mechanics of Insulator Behavior in Concrete Crosstie Fastening Systems

    E-Print Network [OSTI]

    Barkan, Christopher P.L.

    of Insulator Behavior Analysis of failure modes and causes · Failure Mode and Effect Analysis (FMEA) used

  20. SISGR – Domain Microstructures and Mechanisms for Large, Reversible and Anhysteretic Strain Behaviors in Phase Transforming Ferroelectric Materials

    SciTech Connect (OSTI)

    Wang, Yu

    2013-12-06T23:59:59.000Z

    This four-year project (including one-year no-cost extension) aimed to advance fundamental understanding of field-induced strain behaviors of phase transforming ferroelectrics. We performed meso-scale phase field modeling and computer simulation to study domain evolutions, mechanisms and engineering techniques, and developed computational techniques for nanodomain diffraction analysis; to further support above originally planned tasks, we also carried out preliminary first-principles density functional theory calculations of point defects and domain walls to complement meso-scale computations as well as performed in-situ high-energy synchrotron X-ray single crystal diffraction experiments to guide theoretical development (both without extra cost to the project thanks to XSEDE supercomputers and DOE user facility Advanced Photon Source).

  1. On the Significance of Microtubule Flexural Behavior in Cytoskeletal Mechanics

    E-Print Network [OSTI]

    Mofrad, Mohammad R. K.

    occurs in higher modes. This buckling mode switch takes place mostly because of the lateral support in all these modeling approaches is related to the flexural and buckling behavior of microtubular filaments. The objective of this paper is to explore the influence of this flexural and buckling behavior

  2. The normal basilar artery: structural properties and mechanical behavior 

    E-Print Network [OSTI]

    Wicker, Bethany Kay

    2009-05-15T23:59:59.000Z

    is a well established model for vasospasm. However, surprisingly little is known about the mechanical properties of the rabbit basilar artery. Using an in vitro custom organ culture and mechanical testing device, acute and cultured basilar arteries from...

  3. Mechanical behavior of closed-cell and hollow-sphere metallic foams

    E-Print Network [OSTI]

    Sanders, Wynn Steven, 1974-

    2002-01-01T23:59:59.000Z

    (cont.) The elastic anisotropy and yield surfaces are fully characterized, and numerical equations are developed to allow the simple evaluation of the effect of geometric and material properties on the mechanical behavior ...

  4. An Atomistic Study of the Mechanical Behavior of Carbon Nanotubes and Nanocomposite Interfaces 

    E-Print Network [OSTI]

    Awasthi, Amnaya P.

    2011-02-22T23:59:59.000Z

    The research presented in this dissertation pertains to the evaluation of stiffness of carbon nanotubes (CNTs) in a multiscale framework and modeling of the interfacial mechanical behavior in CNT-polymer nanocomposites. The goal is to study...

  5. Microstructure-based Computational Modeling of the Mechanical Behavior of Polymer Micro/Nano-composites 

    E-Print Network [OSTI]

    Heydarkhan Tehrani, Ardeshir

    2013-08-26T23:59:59.000Z

    This dissertation is devoted to the virtual investigation of the mechanical behavior of micro/nano polymer composites (MNPCs). Advanced composite materials are favored by the automotive industry and army departments for their customizable tailored...

  6. Characterization of thermo-mechanical and long-term behaviors of multi-layered composite materials

    E-Print Network [OSTI]

    Nair, Aravind R.

    2009-06-02T23:59:59.000Z

    This study presents characterization of thermo-mechanical viscoelastic and long-term behaviors of thick-section multi-layered fiber reinforced polymer composite materials. The studied multi-layered systems belong to a class of thermo...

  7. Microstructure-based Computational Modeling of the Mechanical Behavior of Polymer Micro/Nano-composites

    E-Print Network [OSTI]

    Heydarkhan Tehrani, Ardeshir

    2013-08-26T23:59:59.000Z

    This dissertation is devoted to the virtual investigation of the mechanical behavior of micro/nano polymer composites (MNPCs). Advanced composite materials are favored by the automotive industry and army departments for their customizable tailored...

  8. CRYSTALLOGRAPHIC PROPERTIES AND MECHANICAL BEHAVIOR OF TITANIUM HYDRIDE LAYERS GROWN ON TITANIUM IMPLANTS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    CRYSTALLOGRAPHIC PROPERTIES AND MECHANICAL BEHAVIOR OF TITANIUM HYDRIDE LAYERS GROWN ON TITANIUM, Switzerland Keywords: SLA treated titanium - bone-anchored dental implants - transmission and scanning electron microscopy - titanium hydride sub-surface layer - epitaxy Abstract Commercially pure titanium

  9. Factors Affecting the Mechanical Behavior of Bone Subrata Saha, Ph.D.

    E-Print Network [OSTI]

    Gilbert, Robert P.

    Factors Affecting the Mechanical Behavior of Bone by Subrata Saha, Ph.D. Research Professor-mail: subrata.saha@downstate.edu ABSTRACT The load carrying capacity of our skeletal system depends

  10. The influence of salinity on the mechanical behavior of high plasticity soils

    E-Print Network [OSTI]

    Fahy, Brian Patrick

    2014-01-01T23:59:59.000Z

    This thesis investigates the influence of salinity on the mechanical behavior of smectitic rich high plasticity soils resedimented with pore fluid salinities ranging from 0 to 256 g/L. An extensive laboratory testing program ...

  11. Coupled Effects of Mechanics, Geometry, and Chemistry on Bio-membrane Behavior

    E-Print Network [OSTI]

    Winfree, Erik

    build and analyze complete models to understand the behavior of multi-component membranes. We proposeCoupled Effects of Mechanics, Geometry, and Chemistry on Bio-membrane Behavior Thesis by Ha Giang, and encouragement. #12;iv Abstract Lipid bilayer membranes are models for cell membranes­the structure that helps

  12. Roles of nanofiller structure on mechanical behavior of thermoplastic nanocomposites

    E-Print Network [OSTI]

    Weon, Jong Il

    2006-10-30T23:59:59.000Z

    -based models accurately describe the relationship between clay structural parameters and the corresponding moduli for exfoliated nanocomposites. The impact fracture mechanisms of polypropylene (PP)-calcium carbonate (CaCO3) nanoparticles have been investigated...

  13. The mechanical behavior of heavily overconsolidated resedimented Boston Blue Clay

    E-Print Network [OSTI]

    Vargas Bustamante, Albalyra Geraldine

    2013-01-01T23:59:59.000Z

    Geotechnical engineers encounter some of the most challenging problems in heavily overconsolidated soils. Clays under this condition originated in nature or man-made construction. This thesis investigates the mechanical ...

  14. MONITORING OF ARTIFICIAL DEFECTS WITHIN A PAVEMENT STRUCTURE WITH A NDT METHOD BASED ON A MECHANICAL IMPACT

    E-Print Network [OSTI]

    Boyer, Edmond

    MONITORING OF ARTIFICIAL DEFECTS WITHIN A PAVEMENT STRUCTURE WITH A NDT METHOD BASED-destructive testing (NDT) method used to monitor a pavement structure which contains artificial defects. A 25 m long pavement section has been built on the full scale accelerated pavement testing facility of IFSTTAR

  15. Atomic-Level Computer Simulation of SiC: Defect Accumulation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Atomic-Level Computer Simulation of SiC: Defect Accumulation, Mechanical Properties and Defect Recovery. Atomic-Level Computer Simulation of SiC: Defect Accumulation, Mechanical...

  16. Mechanisms of classical crystal growth theory explain quartz and silicate dissolution behavior

    E-Print Network [OSTI]

    Dove, Patricia M.

    Mechanisms of classical crystal growth theory explain quartz and silicate dissolution behavior processes was previously unknown for oxides or silicates, our mechanism-based findings are consistent, the geochemistry of earth systems is, in large part, controlled by the kinetics of silicate mineral dissolution

  17. Microstructure and mechanical behavior of ultrafine-grained titanium J. Gubicza1,a

    E-Print Network [OSTI]

    Gubicza, Jenő

    Microstructure and mechanical behavior of ultrafine-grained titanium J. Gubicza1,a , Zs. Fogarassy1@yahoo.com Keywords: Titanium, Equal Channel Angular Pressing (ECAP), radial forging, drawing, microstructure, mechanical properties. Abstract. Ultrafine-grained titanium was processed by severe plastic deformation (SPD

  18. Low temperature electrical and mechanical behavior of composite aluminum cryoconductors

    E-Print Network [OSTI]

    De Frese, Raymond Jack

    1991-01-01T23:59:59.000Z

    was produced by cyclic application ol' a known stress which causes permanent deformation in the pure ahrminum fibers of the conductor. The stress, applied in tension only, was cycled between ten percent of the engineering yield strength (O. les) and some... indicate that the cyclic resistivity behavior of the composite conductor is very much a, function of stress range. An order of magnitude Iv increase in resistivity is usually the result after 3000 stress cycles in the 10-100% stress range. A very small...

  19. Sandia Energy - 2015 VIII MECHANICAL BEHAVIOR OF SALT

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Scienceand Requirements RecentlyElectronicResourcesjobsJulyCatalysts and2015 VIII MECHANICAL

  20. Society for Experimental Mechanics, 2002 SEM Annual Conference Proceedings, Milwaukee, WI, 2002. Mechanical Behavior of Nanostructured Melt Spun NiTi Shape Memory Alloy

    E-Print Network [OSTI]

    Crone, Wendy C.

    . Mechanical Behavior of Nanostructured Melt Spun NiTi Shape Memory Alloy Dabin Wu ć , Wendy C. Crone Ą § ćTi Shape memory alloys (SMAs) were fabricated by cold-rolling melt-spun near equatomic NiTi. SMAs represent. Shape memory behavior was observed in the melt-spun ribbons, and pseudoelasitc behavior was observed

  1. Dry Chamber Wall Thermo-Mechanical Behavior and Lifetime under IFE Cyclic Energy Deposition

    E-Print Network [OSTI]

    California at San Diego, University of

    assessment of dry chamber wall based on ion and photon spectra from a new direct-drive target proposed by NRLDry Chamber Wall Thermo-Mechanical Behavior and Lifetime under IFE Cyclic Energy Deposition Lifetime is a key issue for the IFE dry chamber wall configuration. Past studies, such as SOMBRERO

  2. The mechanical behavior of normally consolidated soils as a function of pore fluid salinity

    E-Print Network [OSTI]

    Horan, Aiden James

    2012-01-01T23:59:59.000Z

    Pore fluid salinities in the Gulf of Mexico area can reach levels of 250 grams of salt per liter of pore fluid (g/1). It is now necessary to determine the effect that this salinity level can play on the mechanical behaviors ...

  3. Phase Transformation Behavior and Mechanical Properties of Thermomechanically Treated K3XF Nickel-Titanium

    E-Print Network [OSTI]

    Zheng, Yufeng

    Phase Transformation Behavior and Mechanical Properties of Thermomechanically Treated K3XF Nickel-Titanium of thermomechanically treated K3XF (SybronEndo, Orange, CA) nickel-titanium instruments in relation to their phase composition was determined by scan- ning electron microscopy with X-ray energy-dispersive spectrometric

  4. Stridulation by Jadera haematoloma (Hemiptera: Rhopalidae): Production Mechanism and Associated Behaviors

    E-Print Network [OSTI]

    Gillooly, Jamie

    BEHAVIOR Stridulation by Jadera haematoloma (Hemiptera: Rhopalidae): Production Mechanism. Soc. Am. 105(1): 118Đ127 (2012); DOI: http://dx.doi.org/10.1603/AN11048 ABSTRACT The Hemiptera related Het- eropteran Hemiptera, the sounds in these other species function primarily in courtship

  5. MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC Jos M. Machado

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    MODEL OF MECHANISM BEHAVIOR FOR VERIFICATION OF PLC PROGRAMS José M. Machado University of Minho on formal methods is now available for checking PLC (Programmable Logic Controller) programs. To verify a PLC program, it is necessary to consider a set of properties to prove and one of the most interesting

  6. Deep structure and mechanical behavior of the lithosphere in the Hangai^Hovsgol region, Mongolia: new constraints from

    E-Print Network [OSTI]

    Déverchčre, Jacques

    Deep structure and mechanical behavior of the lithosphere in the Hangai^Ho«vsgo«l region, Mongolia and mechanical behavior of the lithosphere beneath the Hangai^Ho«vsgo«l region, central Mongolia, Asia, in order rights reserved. Keywords: topography; gravity methods; Mongolia; Hangay Mountains; upper mantle; Łexure

  7. Tuning of the electro-mechanical behavior of the cellular carbon nanotube structures with nanoparticle dispersions

    SciTech Connect (OSTI)

    Gowda, Prarthana; Misra, Abha, E-mail: abha@isu.iisc.ernet.in [Departments of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India)] [Departments of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Ramamurty, Upadrasta [Departments of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India) [Departments of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India); Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-03-10T23:59:59.000Z

    The mechanical and electrical characteristics of cellular network of the carbon nanotubes (CNT) impregnated with metallic and nonmetallic nanoparticles were examined simultaneously by employing the nanoindentation technique. Experimental results show that the nanoparticle dispersion not only enhances the mechanical strength of the cellular CNT by two orders of magnitude but also imparts variable nonlinear electrical characteristics; the latter depends on the contact resistance between nanoparticles and CNT, which is shown to depend on the applied load while indentation. Impregnation with silver nanoparticles enhances the electrical conductance, the dispersion with copper oxide and zinc oxide nanoparticles reduces the conductance of CNT network. In all cases, a power law behavior with suppression in the differential conductivity at zero bias was noted, indicating electron tunneling through the channels formed at the CNT-nanoparticle interfaces. These results open avenues for designing cellular CNT foams with desired electro-mechanical properties and coupling.

  8. An experimental investigation into the stress-dependent mechanical behavior of cohesive soil with application to wellbore instability

    E-Print Network [OSTI]

    Abdulhadi, Naeem Omar

    2009-01-01T23:59:59.000Z

    This thesis investigates the mechanical behavior of cohesive soils with reference to the applications of wellbore instabilities through an extensive program of laboratory element and model borehole tests. The laboratory ...

  9. NUMERICAL SIMULATION FOR MECHANICAL BEHAVIOR OF U10MO MONOLITHIC MINIPLATES FOR RESEARCH AND TEST REACTORS

    SciTech Connect (OSTI)

    Hakan Ozaltun & Herman Shen

    2011-11-01T23:59:59.000Z

    This article presents assessment of the mechanical behavior of U-10wt% Mo (U10Mo) alloy based monolithic fuel plates subject to irradiation. Monolithic, plate-type fuel is a new fuel form being developed for research and test reactors to achieve higher uranium densities within the reactor core to allow the use of low-enriched uranium fuel in high-performance reactors. Identification of the stress/strain characteristics is important for understanding the in-reactor performance of these plate-type fuels. For this work, three distinct cases were considered: (1) fabrication induced residual stresses (2) thermal cycling of fabricated plates; and finally (3) transient mechanical behavior under actual operating conditions. Because the temperatures approach the melting temperature of the cladding during the fabrication and thermal cycling, high temperature material properties were incorporated to improve the accuracy. Once residual stress fields due to fabrication process were identified, solution was used as initial state for the subsequent simulations. For thermal cycling simulation, elasto-plastic material model with thermal creep was constructed and residual stresses caused by the fabrication process were included. For in-service simulation, coupled fluid-thermal-structural interaction was considered. First, temperature field on the plates was calculated and this field was used to compute the thermal stresses. For time dependent mechanical behavior, thermal creep of cladding, volumetric swelling and fission induced creep of the fuel foil were considered. The analysis showed that the stresses evolve very rapidly in the reactor. While swelling of the foil increases the stress of the foil, irradiation induced creep causes stress relaxation.

  10. Who named the quantum defect?

    SciTech Connect (OSTI)

    Rau, A.R.P. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy; Inokuti, M. [Argonne National Lab., IL (United States). Physics Div.

    1997-08-01T23:59:59.000Z

    The notion of the quantum defect is important in atomic and molecular spectroscopy and also in unifying spectroscopy with collision theory. In the latter context, the quantum defect may be viewed as an ancestor of the phase shift. However, the origin of the term quantum defect does not seem to be explained in standard textbooks. It occurred in a 1921 paper by Schroedinger, preceding quantum mechanics, yet giving the correct meaning as an index of the short-range interactions with the core of an atom. The authors present the early history of the quantum-defect idea, and sketch its recent developments.

  11. Percolation mechanism through trapping/de-trapping process at defect states for resistive switching devices with structure of Ag/Si{sub x}C{sub 1?x}/p-Si

    SciTech Connect (OSTI)

    Liu, Yanhong; Gao, Ping; Li, La; Peng, Wei [School of Physics and Optoelectronic Engineering, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China); Jiang, Xuening; Zhang, Jialiang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China)

    2014-08-14T23:59:59.000Z

    Pure Si{sub x}C{sub 1?x} (x?>?0.5) and B-containing Si{sub x}C{sub 1?x} (x?>?0.5) based resistive switching devices (RSD) with the structure of Ag/Si{sub x}C{sub 1?x}/p-Si were fabricated and their switching characteristics and mechanism were investigated systematically. Percolation mechanism through trapping/ de-trapping at defect states was suggested for the switching process. Through the introduction of B atoms into Si{sub x}C{sub 1?x}, the density of defect states was reduced, then, the SET and RESET voltages were also decreased. Based on the percolation theory, the dependence of SET/RESET voltage on the density of defect states was analyzed. These results supply a deep understanding for the SiC-based RSD, which have a potential application in extreme ambient conditions.

  12. Mechanical properties and corrosion behavior of materials exposed to an experimental, atmospheric fluidized-bed combustor

    SciTech Connect (OSTI)

    Ganesan, P.; Sagues, A.; Sethi, V.

    1984-06-01T23:59:59.000Z

    A joint materials test program developed by the Institute for Mining and Minerals Research (IMMR) and the Tennessee Valley Authority (TVA) involved the postexposure mechanical properties and corrosion behavior of candidate structural materials in an experimental, atmospheric fluidized-bed combustor (AFBC). This combustor was operated by Accurex Corporation at Research Triangle Park, North Carolina, under the direction of TVA. The materials studied were Type 304, Type 310, and INCOLOY alloy 800 in the form of disc coupons with and without crevice configurations. Type 304 was also used for mechanical property measurements. The alloys were exposed to the combustor environment at about840/sup 0/C for approximately 330 hours. The ranking in terms of decreasing weight loss was: (1) Type 304, (2) Type 310, and (3) INCOLOY alloy 800. The presence of tight crevices did not enhance the corrosion rate. In addition, the corrosion rates, based on the weight loss (typically 1 to 6 mpy), indicated that the alloys performed reasonably well when considering materials wastage. However, optical microscopy observations showed intergranular corrosion penetration in INCOLOY alloy 800 and Type 304. The mechanical properties of Type 304 were inferior to the unexposed alloy. A comparison of the data obtained from the combustor-exposed 304ss tensile samples with data from control samples exposed in vacuum to a similar thermal history indicated that the chemistry of the AFBC environment did not play a major role in the observed degradation of the mechanical properties.

  13. Damage mechanics characterization on fatigue behavior of a solder joint material

    SciTech Connect (OSTI)

    Chow, C.L.; Yang, F. [Univ. of Michigan, Dearborn, MI (United States). Dept. of Mechanical Engineering; Fang, H.E. [Sandia National Labs., Albuquerque, NM (United States). Computational Physics Dept.

    1998-08-01T23:59:59.000Z

    This paper presents the first part of a comprehensive mechanics approach capable of predicting the integrity and reliability of solder joint material under fatigue loading without viscoplastic damage considerations. A separate report will be made to present a comprehensive damage model describing life prediction of the solder material under thermomechanical fatigue loading. The method is based on a theory of damage mechanics which makes possible a macroscopic description of the successive material deterioration caused by the presence of microcracks/voids in engineering materials. A damage mechanics model based on the thermodynamic theory of irreversible processes with internal state variables is proposed and used to provide a unified approach in characterizing the cyclic behavior of a typical solder material. With the introduction of a damage effect tensor, the constitutive equations are derived to enable the formulation of a fatigue damage dissipative potential function and a fatigue damage criterion. The fatigue evolution is subsequently developed based on the hypothesis that the overall damage is induced by the accumulation of fatigue and plastic damage. This damage mechanics approach offers a systematic and versatile means that is effective in modeling the entire process of material failure ranging from damage initiation and propagation leading eventually to macro-crack initiation and growth. As the model takes into account the load history effect and the interaction between plasticity damage and fatigue damage, with the aid of a modified general purpose finite element program, the method can readily be applied to estimate the fatigue life of solder joints under different loading conditions.

  14. Microstructural and mechanical behavior of a duplex stainless steel under hot working conditions

    SciTech Connect (OSTI)

    Iza-Mendia, A. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, San Sebastian (Spain). Dept. of Materials]|[Univ. of Navarra, San Sebastian (Spain); Pinol-Juez, A. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, San Sebastian (Spain). Dept. of Materials; Urcola, J.J.; Gutierrez, I. [Univ. of Navarra, San Sebastian (Spain)

    1998-12-01T23:59:59.000Z

    In the hot deformation of the duplex stainless steels, the complexity of the microstructure evolution and mechanical response is increased as compared with those of single-phase ferritic or austenitic stainless steels. In the present work, plane strain compression and torsion deformation modes have been used to analyze the microstructural evolution and the mechanical behavior of a duplex stainless steel in as-cast and wrought conditions, as a function of spatial phase distribution, the nature of interface, and the relative mechanical properties of both phases. The law of mixtures has been used to explain the different flow curves obtained when changing the phase distribution and/or the deformation mode. On deforming as-cast microstructures, the deformation partitions vary heterogeneously between both phases and some austenite areas act as hard nondeforming particles. Cracks have been observed to occur at the interface of such regions, from relatively low strains, for which the initial Kurdjumov-Sachs orientation relationship between ferrite and austenite is still present.

  15. Predicting the Operating Behavior of Ceramic Filters from Thermo-Mechanical Ash Properties

    SciTech Connect (OSTI)

    Hemmer, G.; Kasper, G.

    2002-09-19T23:59:59.000Z

    Stable operation, in other words the achievement of a succession of uniform filtration cycles of reasonable length is a key issue in high-temperature gas filtration with ceramic media. Its importance has rather grown in recent years, as these media gain in acceptance due to their excellent particle retention capabilities. Ash properties have been known for some time to affect the maximum operating temperature of filters. However, softening and consequently ''stickiness'' of the ash particles generally depend on composition in a complex way. Simple and accurate prediction of critical temperature ranges from ash analysis--and even more so from coal analysis--is still difficult without practical and costly trials. In general, our understanding of what exactly happens during break-down of filtration stability is still rather crude and general. Early work was based on the concept that ash particles begin to soften and sinter near the melting temperatures of low-melting, often alkaline components. This softening coincides with a fairly abrupt increase of stickiness, that can be detected with powder mechanical methods in a Jenicke shear cell as first shown by Pilz (1996) and recently confirmed by others (Kamiya et al. 2001 and 2002, Kanaoka et al. 2001). However, recording {sigma}-{tau}-diagrams is very time consuming and not the only off-line method of analyzing or predicting changes in thermo-mechanical ash behavior. Pilz found that the increase in ash stickiness near melting was accompanied by shrinkage attributed to sintering. Recent work at the University of Karlsruhe has expanded the use of such thermo-analytical methods for predicting filtration behavior (Hemmer 2001). Demonstrating their effectiveness is one objective of this paper. Finally, our intent is to show that ash softening at near melting temperatures is apparently not the only phenomenon causing problems with filtration, although its impact is certainly the ''final catastrophe''. There are other significant changes in regeneration at intermediate temperatures, which may lead to long-term deterioration.

  16. Modeling Frameworks for Representing the Mechanical Behavior of Tissues with a Specific Look at Vasculature

    E-Print Network [OSTI]

    Andersohn, Alexander

    2013-08-27T23:59:59.000Z

    Many mechanicstic models aimed at predicting tissue behavior attempt to connect constitutive factors (such as effects due to collagen or fibrin concentrations) with the overall tissue behavior. Such a link between constitutive and material behaviors...

  17. {l_brace}311{r_brace} Defects in ion-implanted silicon: The cause of transient diffusion, and a mechanism for dislocation formation

    SciTech Connect (OSTI)

    Eaglesham, D.J.; Stolk, P.A.; Cheng, J.Y.; Gossmann, H.J.; Poate, J.M. [AT and T Bell Labs., Murray Hill, NJ (United States); Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.

    1995-04-01T23:59:59.000Z

    Ion implantation is used at several critical stages of Si integrated circuit manufacturing. The authors show how {l_brace}311{r_brace} defects arising after implantation are responsible for both enhanced dopant diffusion during annealing, and stable dislocations post-anneal. They observe {l_brace}311{r_brace} defects in the earliest stages of an anneal. They subsequently undergo rapid Ostwald ripening and evaporation. At low implant doses evaporation dominates, and they can quantitatively relate the interstitials emitted from these defects to the transient enhancement in diffusivity of dopants such as B and P. At higher doses Ostwald ripening is significant, and they observe the defects to undergo a series of unfaulting reactions to form both Frank loops and perfect dislocations. They demonstrate the ability to control both diffusion and dislocations by the addition of small amounts of carbon impurities.

  18. Mass-Spring Model for Simulation of Heart Valve Tissue Mechanical Behavior Peter E. Hammer1,2,4,*

    E-Print Network [OSTI]

    1 Mass-Spring Model for Simulation of Heart Valve Tissue Mechanical Behavior Peter E. Hammer1, Cambridge, MA Abbreviated title: Mass-Spring Model for Simulation of Heart Valve Tissue * Address, MA, USA. E-mail address: peter.hammer@childrens.harvard.edu. #12;2 Abstract Heart valves

  19. Microstructure, mechanical property, biodegradation behavior, and biocompatibility of biodegradable FeFe2O3 composites

    E-Print Network [OSTI]

    Zheng, Yufeng

    behaviors, and in vitro biocompatibility of Fe­ Fe2O3 composites fabricated by spark plasma sintering were

  20. Fundamental Processes of Coupled Radiation Damage and Mechanical Behavior in Nuclear Fuel Materials for High Temperature Reactors

    SciTech Connect (OSTI)

    Phillpot, Simon; Tulenko, James

    2011-09-08T23:59:59.000Z

    The objective of this work has been to elucidate the relationship among microstructure, radiation damage and mechanical properties for nuclear fuel materials. As representative nuclear materials, we have taken an hcp metal (Mg as a generic metal, and Ti alloys for fast reactors) and UO2 (representing fuel). The degradation of the thermo-mechanical behavior of nuclear fuels under irradiation, both the fissionable material itself and its cladding, is a longstanding issue of critical importance to the nuclear industry. There are experimental indications that nanocrystalline metals and ceramics may be more resistant to radiation damage than their coarse-grained counterparts. The objective of this project look at the effect of microstructure on radiation damage and mechanical behavior in these materials. The approach to be taken was state-of-the-art, large-scale atomic-level simulation. This systematic simulation program of the effects of irradiation on the structure and mechanical properties of polycrystalline Ti and UO2 identified radiation damage mechanisms. Moreover, it will provided important insights into behavior that can be expected in nanocrystalline microstructures and, by extension, nanocomposites. The fundamental insights from this work can be expected to help in the design microstructures that are less susceptible to radiation damage and thermomechanical degradation.

  1. EFFECTS OF MORPHOLOGY ON THE MECHANICAL BEHAVIOR OF DUAL PHASE Fe/Si/C STEELS

    E-Print Network [OSTI]

    Kim, N.J.

    2012-01-01T23:59:59.000Z

    and ductility in dual phase steels. However, it seems thatmechanical behavior of dual phase steels. ACKNOWLEDGEMENTSL INTRODUCTION Dual phase steels whose structures consist of

  2. Dilatation-strain analysis of the effects of flaws on the mechanical behavior of a highly filled elastomer

    E-Print Network [OSTI]

    Smith, Benjamin Ray

    1966-01-01T23:59:59.000Z

    as to style and content by: (Chairman of Committee) (Head of Department) (Member) August 1966 460008 ABSTRACT Dilatation-Strain Analysis of the Effects of Flaws on the Mechanical Behavior of a Highly Filled Elastomer Benjamin Ray Smith, B. S. , Texas... and from plates of solid propellant milled to 0. 250 inches in thick- ness. These materials were supplied by the Rocketdyne Division of North American Aviation. Their designation for the propellant is RDS-500. Their properties, which were found in other...

  3. Mechanical and optical behavior of a novel optical fiber crack sensor and an interferometric strain sensor

    E-Print Network [OSTI]

    Olson, Noah Gale, 1969-

    2002-01-01T23:59:59.000Z

    The proper interpretation of measurements from an optical fiber sensor requires a full understanding of its mechanical response to external action and the corresponding change in optical output. To quantify the mechanical ...

  4. Fusion Engineering and Design 3940 (1998) 759764 Mechanical behavior and design database of packed beds for

    E-Print Network [OSTI]

    Abdou, Mohamed

    of packed beds for blanket designs Alice Y. Ying *, Zi Lu, Mohamed A. Abdou Mechanical and Aerospace

  5. Asperity-scale surface mechanics - Implications to adhesive contacts and microscale deformation behavior of rough surfaces

    E-Print Network [OSTI]

    Xu, Huaming

    2012-01-01T23:59:59.000Z

    Microtribology for Microelectromechanical Systems,” Wear,forces in microelectromechanical systems: mechanisms,Analysis Microelectromechanical Systems,” ASME J. Tribol. ,

  6. Defect CFTs and holographic multiverse

    E-Print Network [OSTI]

    Bartomeu Fiol

    2010-04-09T23:59:59.000Z

    We investigate some aspects of a recent proposal for a holographic description of the multiverse. Specifically, we focus on the implications on the suggested duality of the fluctuations of a bubble separating two universes with different cosmological constants. We do so by considering a similar problem in a 2+1 CFT with a codimension one defect, obtained by an M5-brane probe embedding in AdS_4x S^7, and studying its spectrum of fluctuations. Our results suggest that the kind of behavior required by the spectrum of bubble fluctuations is not likely to take place in defect CFTs with an AdS dual, although it might be possible if the defect supports a non-unitary theory.

  7. Defect CFTs and holographic multiverse

    SciTech Connect (OSTI)

    Fiol, Bartomeu, E-mail: bfiol@ub.edu [Departament de Física Fonamental i Institut de Cičncies del Cosmos, Universitat de Barcelona, Martí i Franqučs 1, 08193 Barcelona (Spain)

    2010-07-01T23:59:59.000Z

    We investigate some aspects of a recent proposal for a holographic description of the multiverse. Specifically, we focus on the implications on the suggested duality of the fluctuations of a bubble separating two universes with different cosmological constants. We do so by considering a similar problem in a 2+1 CFT with a codimension one defect, obtained by an M5-brane probe embedding in AdS{sub 4} × S{sup 7}, and studying its spectrum of fluctuations. Our results suggest that the kind of behavior required by the spectrum of bubble fluctuations is not likely to take place in defect CFTs with an AdS dual, although it might be possible if the defect supports a non-unitary theory.

  8. Discrete particle transport in porous media : discrete observations of physical mechanisms influencing particle behavior

    E-Print Network [OSTI]

    Yoon, Joon Sik, 1973-

    2005-01-01T23:59:59.000Z

    An understanding of how discrete particles in the micron to submicron range behave in porous media is important to a number of environmental problems. Discrete particle behavior in the interior of a porous medium is complex ...

  9. The consolidation and strength behavior of mechanically compressed fine-grained sediments

    E-Print Network [OSTI]

    Casey, Brendan (Brendan Anthony)

    2014-01-01T23:59:59.000Z

    This thesis investigates the consolidation and shear strength behavior of saturated fine-grained sediments over the effective stress range of 0.1 to 100 MPa. The research makes use of samples which are resedimented in the ...

  10. Mechanical behavior of tissue simulants and soft tissues under extreme loading conditions

    E-Print Network [OSTI]

    Kalcioglu, Zeynep Ilke

    2013-01-01T23:59:59.000Z

    Recent developments in computer-integrated surgery and in tissue-engineered constructs necessitate advances in experimental and analytical techniques in characterizing properties of mechanically compliant materials such ...

  11. Mechanical behaviors and phase transition of Ho{sub 2}O{sub 3} nanocrystals under high pressure

    SciTech Connect (OSTI)

    Yan, Xiaozhi [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Rd., Pudong, Shanghai 201203 (China); Ren, Xiangting [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); He, Duanwei, E-mail: duanweihe@scu.edu.cn, E-mail: yangwg@hpstar.ac.cn [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Institute of Fluid Physics and National Key Laboratory of Shockwave and Detonation Physic, China Academy of Engineering Physics, Mianyang 621900 (China); Chen, Bin [Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Rd., Pudong, Shanghai 201203 (China); Yang, Wenge, E-mail: duanweihe@scu.edu.cn, E-mail: yangwg@hpstar.ac.cn [Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Rd., Pudong, Shanghai 201203 (China); High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, 9700 S Cass Avenue, Argonne, Illinois 60439 (United States)

    2014-07-21T23:59:59.000Z

    Mechanical properties and phase transition often show quite large crystal size dependent behavior, especially at nanoscale under high pressure. Here, we have investigated Ho{sub 2}O{sub 3} nanocrystals with in-situ x-ray diffraction and Raman spectroscopy under high pressure up to 33.5?GPa. When compared to the structural transition routine cubic -> monoclinic -> hexagonal phase in bulk Ho{sub 2}O{sub 3} under high pressure, the nano-sized Ho{sub 2}O{sub 3} shows a much higher onset transition pressure from cubic to monoclinic structure and followed by a pressure-induced-amorphization under compression. The detailed analysis on the Q (Q?=?2?/d) dependent bulk moduli reveals the nanosized Ho{sub 2}O{sub 3} particles consist of a clear higher compressible shell and a less compressible core. Insight into these phenomena shed lights on micro-mechanism studies of the mechanical behavior and phase evolution for nanomaterials under high pressure, in general.

  12. Microstructure, strengthening mechanisms and hot deformation behavior of an oxide-dispersion strengthened UFG Al6063 alloy

    SciTech Connect (OSTI)

    Asgharzadeh, H. [Department of Mechanical Engineering, University of Tabriz, P.O. Box 51666-16471, Tabriz (Iran, Islamic Republic of)] [Department of Mechanical Engineering, University of Tabriz, P.O. Box 51666-16471, Tabriz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, P.O. Box 790-784, Pohang (Korea, Republic of)] [Department of Materials Science and Engineering, Pohang University of Science and Technology, P.O. Box 790-784, Pohang (Korea, Republic of); Simchi, A., E-mail: simchi@sharif.edu [Department of Materials Science and Engineering and Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)

    2013-01-15T23:59:59.000Z

    An ultrafine-grained Al6063/Al{sub 2}O{sub 3} (0.8 vol.%, 25 nm) nanocomposite was prepared via powder metallurgy route through reactive mechanical alloying and hot powder extrusion. Scanning electron microcopy, transmission electron microscopy, and back scattered electron diffraction analysis showed that the grain structure of the nanocomposite is trimodal and composed of nano-size grains (< 0.1 {mu}m), ultrafine grains (0.1-1 {mu}m), and micron-size grains (> 1 {mu}m) with random orientations. Evaluation of the mechanical properties of the nanocomposite based on the strengthening-mechanism models revealed that the yield strength of the ultrafine-grained nanocomposite is mainly controlled by the high-angle grain boundaries rather than nanometric alumina particles. Hot deformation behavior of the material at different temperatures and strain rates was studied by compression test and compared to coarse-grained Al6063 alloy. The activation energy of the hot deformation process for the nanocomposite was determined to be 291 kJ mol{sup -1}, which is about 64% higher than that of the coarse-grained alloy. Detailed microstructural analysis revealed that dynamic recrystallization is responsible for the observed deformation softening in the ultrafine-grained nanocomposite. - Highlights: Black-Right-Pointing-Pointer The strengthening mechanisms of Al6063/Al{sub 2}O{sub 3} nanocomposite were evaluated. Black-Right-Pointing-Pointer Hot deformation behavior of the nanocomposite was studied. Black-Right-Pointing-Pointer The hot deformation activation energy was determined using consecutive models. Black-Right-Pointing-Pointer The restoration mechanisms and microstructural changes are presented.

  13. Vehicle Technologies Office Merit Review 2014: Coupling of Mechanical Behavior of Cell Components to Electrochemical-Thermal Models for Computer-Aided Engineering of Batteries under Abuse

    Broader source: Energy.gov [DOE]

    Presentation given by NREL at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about coupling of mechanical behavior of cell...

  14. How do quantum effects change conclusions about heterogeneous cluster behavior based on classical mechanics simulations?

    E-Print Network [OSTI]

    Le Roy, Robert J.

    February 1998 Comparisons of classical and quantum Monte Carlo simulation of SF6­ Ar n and SF6­ Ne n clusters are used to examine whether certain novel types of behavior seen in classical simulations of SF6­ Ar n and SF6­ Kr n persist when quantum effects are taken into account. For mixed clusters formed

  15. Mechanisms of Mating-Behavior Deterioration in Early Aging Male C. elegans 

    E-Print Network [OSTI]

    Guo, Xiaoyan

    2014-08-06T23:59:59.000Z

    . This is consistent with the observation that old males exhibit reduced control over their ability to mate. Caloric restriction is an efficient non-genetic intervention to increase lifespan. I demonstrated here that it also improves mating behavior in 3-day-old males...

  16. Dynamic behavior of Ni80Fe20 nanowires with controlled defects J. Ding, V. E. Demidov, M. G. Cottam, S. O. Demokritov, and A. O. Adeyeye

    E-Print Network [OSTI]

    Adeyeye, Adekunle

    and reversal mechanism of Fe filled Ni80Fe20 antidot nanostructures Appl. Phys. Lett. 100, 242411 (2012); 10 Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National for microwave devices1 and domain wall logic devices.2 Coupled nanowire arrays have also been investigated

  17. Production, Characterization, and Mechanical Behavior of Cementitious Materials Incorporating Carbon Nanofibers 

    E-Print Network [OSTI]

    Yazdanbakhsh, Ardavan

    2012-10-19T23:59:59.000Z

    particles is an important parameter and poorly dispersed silica fume cannot enhance the overall dispersion of nano inclusions in cementitious materials. Finally, the mechanical testing and experimentations showed that CNFs, in absence of moist curing, even...

  18. Role of the precentral cortex in adapting behavior to different mechanical environments

    E-Print Network [OSTI]

    Richardson, Andrew Garmory, 1977-

    2007-01-01T23:59:59.000Z

    We routinely produce movements under different mechanical contexts. All interactions with the physical environment, such as swinging a hammer or lifting a carton of milk, alter the forces experienced during movement. With ...

  19. Mechanisms leading to erratic snapback behavior in bipolar junction transistors with base emitter shorted

    E-Print Network [OSTI]

    of avalanche injection in p/n- /n+ structures show that two very close breakdown states coexist. The mechanisms to an avalanche breakdown and a delay time before the initiation of the breakdown.2­14 Typically, shorter delays Science, Vanderbilt University, Nashville, Tennessee 37235 Sameer Pendharkar Texas Instruments Inc., 13560

  20. Behavior of Turbulent Structures within a Mach 5 Mechanically Distorted Boundary Layer

    E-Print Network [OSTI]

    Peltier, Scott Jacob

    2013-08-05T23:59:59.000Z

    field of incompressible boundary layer, taken from Adrian et al. (2000). ............................................................................... 138 Figure 6.15 Schematic of an individual hairpin vortex, describing the sweep and ejection... hairpin vortex, identifying the motions contributing to sweeps and ejections ....................................................................................... 235 Figure 7.46 Illustrations of the possible mechanisms contributing to the reduced...

  1. ME 378K Mechanical Behavior of Materials ABET EC2000 syllabus

    E-Print Network [OSTI]

    Ben-Yakar, Adela

    of contemporary issues in engineering practice, including economic, social, political, and environmental issues. Apply principles of engineering, basic science, and mathematics (including multivariate calculus: For engineering majors, Mechanical Engineering 336 and 136L with a grade of at least C in each, and admission

  2. The effects of texture and composition on the mechanical behavior of experimentally deformed carbonate rocks 

    E-Print Network [OSTI]

    Hugman, Robert Harvey Harold

    1978-01-01T23:59:59.000Z

    behavior in unconfined tests and large increases in ultimate strength with increases in confining pressure to 100 MPa (Fig. 1, a, e). These "crystalline" rocks are moderately ductile to ductile at 100 MPa confining pressure. A degree of work hardening... Limestone (67 0 microcrystalline carbonate), and Madison H61-16 Lime- stone (54 $ micrite) are included in this category (Fig. 1, b, d, f), All these rocks are strong in unconfined tests, and stronger at 50 and 100 MPa confining pressure then Yule Marble...

  3. Research into the microstructure and mechanical behavior of eutectic Bi-Sn and In-Sn

    SciTech Connect (OSTI)

    Goldstein, J.L.F.; Mei, Z.; Morris, J.W. Jr. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1993-08-01T23:59:59.000Z

    This manuscript reports on research into two low-melting, lead-free solder alloys, eutectic Bi-Sn and eutectic In-Sn. The microstructures were found to depend on both cooling rate and substrate, with the greatest variability in the In-Sn alloy. The nature of the intermetallic layer formed at the solder-substrate interface depends on both the solder and the substrate (Cu versus Ni). Also, the microstructure of the Bi-Sn can recrystallize during deformation, which is not the case with In-Sn. Data from creep and constant strain rate tests are given for slowly cooled samples. The creep behavior of In-Sn is constant with temperature, but the creep seems to be controlled by the In-rich phase in In-Sn on Cu and by the Sn-rich phase in In-Sn on Ni. Bi-Sn exhibits different creep behavior at temperatures above 40 {degrees}C than at 20 {degrees}C or lower. Stress-strain curves of Bi-Sn on Cu and In-Sn on Cu are similar, while In-Sn on Ni behaves differently. This is explained in terms of the deformation patterns in the alloys.

  4. Behavior of Laterally Loaded Shafts Constructed Behind the Face of a Mechanically Stabilized Earth Block Wall

    E-Print Network [OSTI]

    Pierson, Matthew Charles

    2008-04-30T23:59:59.000Z

    for all the failure mechanisms of conventional retaining walls. In addition, MSE walls must be designed for modes of failure unique to MSE walls. Failure of an MSE wall can occur several ways: sliding of layers, pullout of the reinforcement, elongation... lagging and panels, and wrapped sheets of geosynthetics? (FHWA, 1996). Most MSE systems use either a galvanized or epoxy coated steel reinforcement, or synthetic reinforcement like high density polyethylene (HDPE), polypropylene, or polyester yarn...

  5. Phase transformation and mechanical behavior in annealed 2205 duplex stainless steel welds

    SciTech Connect (OSTI)

    Badji, Riad [LPMTM-CNRS- Universite Paris 13, 99, av. J.B. Clement, 93430 Villetaneuse (France)], E-mail: riadbadji1@yahoo.fr; Bouabdallah, Mabrouk [Ecole Nationale Polytechnique, 10, Avenue Hassan Badi, BP 182, El Harrach (Algeria); Bacroix, Brigitte; Kahloun, Charlie [LPMTM-CNRS- Universite Paris 13, 99, av. J.B. Clement, 93430 Villetaneuse (France); Belkessa, Brahim; Maza, Halim [Welding and NDT research Centre, B.P 64, Cheraga (Algeria)

    2008-04-15T23:59:59.000Z

    The phase transformations and mechanical behaviour during welding and subsequent annealing treatment of 2205 duplex stainless steel have been investigated. Detailed microstructural examination showed the presence of higher ferrite amounts in the heat affected zone (HAZ), while higher amounts of austenite were recorded in the centre region of the weld metal. Annealing treatments in the temperature range of 800-1000 deg. C resulted in a precipitation of {sigma} phase and M{sub 23}C{sub 6} chromium carbides at the {gamma}/{delta} interfaces that were found to be preferential precipitation sites. Above 1050 deg. C, the volume fraction of {delta} ferrite increases with annealing temperature. The increase of {delta} ferrite occurs at a faster rate in the HAZ than in the base metal and fusion zone. Optimal mechanical properties and an acceptable ferrite/austenite ratio throughout the weld regions corresponds to annealing at 1050 deg. C. Fractographic examinations showed that the mode of failure changed from quasi-cleavage fracture to dimple rupture with an increase in the annealing temperature from 850 to 1050 deg. C.

  6. Further investigation of the characteristics of nodular defects

    SciTech Connect (OSTI)

    Liu Xiaofeng; Li Dawei; Zhao Yuan'an; Li Xiao

    2010-04-01T23:59:59.000Z

    To increase the understanding of the damage sensitivity of nodular defects and provide exact evidence for theoretical study, the structures and the damage behavior of nodular defects in electron-beam deposited mirrors of HfO2/SiO2 are systemically investigated with a double-beam microscope (focused ion beam, scanning electron microscope). Nodular defects are classified into two kinds. In one kind the boundaries between nodules and the surrounding layers have become continuous for the last deposited materials, and in the other there are discontinuous boundaries between nodules and the surrounding layers. Nodular defects of the first kind typically have low domes, and the second have high domes. Laser damage experiments show that nodular defects of the first kind usually have a high laser resistance, and the laser-induced damage thresholds are limited in the second class of nodules. The dominant parameter of nodular defects related to damage is the height of the nodular defect.

  7. Mechanical Behavior Analysis of a Test Coil for MICE Coupling Solenoid during Quench

    SciTech Connect (OSTI)

    Pan, Heng; Wang, Li; Guo, Xinglong; Wu, Hong; Green, M.A.

    2009-10-28T23:59:59.000Z

    The coupling magnet for the Muon Ionization Cooling Experiment has a self-inductance of 592 H and the magnet stored energy of 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The high level of stored energy in the magnet can cause high peak temperature during a quench and induce considerable impact of stresses. One test coil was built in order to validate the design method and to practice the stress and strain situation to occur in the coupling coil. In this study, the analysis on stress redistribution during a quench with sub-divided winding was performed. The stress variation may bring about failure of impregnating material such as epoxy resin, which is the curse of a new normal zone arising. Spring models for impregnating epoxy and fiber-glass cloth in the coil were used to evaluate the mechanical disturbance by impregnated materials failure. This paper presents the detailed dynamic stress and stability analysis to assess the stress distribution during the quench process and to check whether the transient loads are acceptable for the magnet.

  8. Effect of fiber architecture on mechanical behavior of SiC(f)/SiC composites

    SciTech Connect (OSTI)

    Singh, D.; Singh, J.P.; Sutaria, M.

    1997-01-01T23:59:59.000Z

    We evaluated mechanical properties (first matrix cracking stress, strength, and work-of-fracture) of Nicalon-fiber-reinforced silicon carbide matrix composites with three different fiber lay-up sequences (0{degrees}/20{degrees}/60{degrees}, 0{degrees}/40{degrees}/60{degrees}, and 0{degrees}/45{degrees}) at various temperatures from room to 1300{degrees}C. Up to 1200{degrees}C, ultimate strength and work-of-fracture for the 0{degrees}/40{degrees}/60{degrees} and 0{degrees}/45{degrees} composites increased, but then declined at 1300{degrees}C. The decreases were correlated to in-situ Nicalon fiber strength and fiber/matrix interface degradation. However, for the 0{degrees}/20{degrees}/60{degrees} composites, ultimate strength and work-of-fracture reached their a minima at 1200{degrees}C. These measured ultimate strengths at room and 1300{degrees}C were correlated to the predictions made with an analytical model and to in-situ fiber strength characteristics. The large difference in room-temperature ultimate strengths between the three sets of composites is attributed to the relative contributions of the off-axis fibers to the load-bearing capacity of each composite.

  9. Modeling rough energy landscapes in defected condensed matter

    E-Print Network [OSTI]

    Monasterio Velásquez, Paul Rene

    2010-01-01T23:59:59.000Z

    This dissertation is a computational and theoretical investigation of the behavior of defected condensed matter and its evolution over long time scales. The thesis provides original contributions to the methodology used ...

  10. Final Technical Report of project: "Contactless Real-Time Monitoring of Paper Mechanical Behavior During Papermaking"

    SciTech Connect (OSTI)

    Emmanuel Lafond; Paul Ridgway; Ted Jackson; Rick Russo; Ken Telschow; Vance Deason; Yves Berthelot; David Griggs; Xinya Zhang; Gary Baum

    2005-08-30T23:59:59.000Z

    The early precursors of laser ultrasonics on paper were Prof. Y. Berthelot from the Georgia Institute of Technology/Mechanical Engineering department, and Prof. P. Brodeur from the Institute of Paper Science and Technology, both located in Atlanta, Georgia. The first Ph.D. thesis that shed quite some light on the topic, but also left some questions unanswered, was completed by Mont A. Johnson in 1996. Mont Johnson was Prof. Berthelot's student at Georgia Tech. In 1997 P. Brodeur proposed a project involving himself, Y. Berthelot, Dr. Ken Telschow and Mr. Vance Deason from INL, Honeywell-Measurex and Dr. Rick Russo from LBNL. The first time the proposal was not accepted and P. Brodeur decided to re-propose it without the involvement from LBNL. Rick Russo proposed a separate project on the same topic on his side. Both proposals were finally accepted and work started in the fall of 1997 on the two projects. Early on, the biggest challenge was to find an optical detection method which could detect laser-induced displacements of the web surface that are of the order of .1 micron in the ultrasonic range. This was to be done while the web was having an out-of-plane amplitude of motion in the mm range due to web flutter; while moving at 10 m/s to 30 m/s in the plane of the web, on the paper machine. Both teams grappled with the same problems and tried similar methods in some cases, but came up with two similar but different solutions one year later. The IPST, GT, INL team found that an interferometer made by Lasson Technologies Inc. using the photo-induced electro-motive force in Gallium Arsenide was able to detect ultrasonic waves up to 12-15 m/s. It also developed in house an interferometer using the Two-Wave Mixing effect in photorefractive crystals that showed good promises for on-line applications, and experimented with a scanning mirror to reduce motion-induced texture noise from the web and improve signal to noise ratio. On its side, LBNL had the idea to combine a commercial Mach-Zehnder interferometer to a spinning mirror synchronized to the web speed, in order to make almost stationary measurements. The method was demonstrated at up to 10 m/s. Both teams developed their own version of a web simulator that was driving a web of paper at 10 m/s or higher. The Department of Energy and members of the Agenda 2020 started to make a push for merging the two projects. This made sense because their topics were really identical but this was not well received by Prof. Brodeur. Finally IPST decided to reassign the direction of the IPST-INL-GT project in the spring of 1999 to Prof. Chuck Habeger so that the two teams could work together. Also at this time, Honeywell-Measurex dropped as a member of the team. It was replaced by ABB Industrial Systems whose engineers had extensive previous experience of working with ultrasonic sensors on paperboard. INL also finished its work on the project as its competencies were partly redundant with LBNL. From the summer of 1999, the IPST-GT and LBNL teams were working together and helped each other often by collaborating and visiting either laboratory when was necessary. Around the beginning of 2000, began an effort at IPST to create an off-line laser-ultrasonics instrument that could perform automated measurements of paper and paperboard's bending stiffness. It was widely known that the mechanical bending tests of paper used for years by the paper industry were very inaccurate and exhibited poor reproducibility; therefore the team needed a new instrument of reference to validate its future on-line results. In 1999-2000, the focus of the on-line instrument was on a pre-industrial demonstration on a pilot coater while reducing the damage to the web caused by the generation laser, below the threshold where it could be visible by the naked eye. During the spring of 2000 Paul Ridgway traveled to IPST and brought with him a redesigned system still using the same Mach-Zehnder interferometer as before, but this time employing an electric motor-driven spinning mirror instead of the previously belt-driven m

  11. Hydro-mechanical behavior of Municipal Solid Waste subject to leachate recirculation in a large-scale compression reactor cell

    SciTech Connect (OSTI)

    Olivier, Franck [Environment, Energy and Waste Research Center (CREED), 291, avenue Dreyfous Ducas, 78520 Limay (France) and Laboratoire LIRIGM - Maison des Geosciences, 1381, rue de la piscine 38400 Saint-Martin d'Heres (France)]. E-mail: franck.olivier@ujf-grenoble.fr; Gourc, Jean-Pierre [Laboratoire LIRIGM - Maison des Geosciences, 1381, rue de la piscine 38400 Saint-Martin d'Heres (France)]. E-mail: gourc@ujf-grenoble.fr

    2007-07-01T23:59:59.000Z

    The paper presents the results of a laboratory experiment on Municipal Solid Waste (MSW) subjected to one-dimensional compression in a 1 m{sup 3} instrumented cell. The focus was on the hydro-mechanical behavior of the material under conditions of confinement and leachate percolation that replicate those found in real-scale landfills. The operation of the apparatus is detailed together with the testing methodology and the monitoring program. Two samples of waste were tested: the first extended over a period of 10 months ('Control Test') and the second for 22 months ('Enhanced Test' with leachate recirculation). Consolidation data is reported with regard to both short-term (stress-dependent) and long-term (time-dependent) settlements. A discussion follows based on the derived values of primary and secondary compression ratios. Correlations between compression parameters and the biodegradation process are presented. In particular, results clearly highlight the effect of leachate recirculation on waste settlement: 24% secondary deformation reached after slightly less than 2 years (equivalent to a 5-fold increase in compressibility) and 17.9% loss of dry matter. Comparisons are proposed considering the results derived from the few monitoring programs conducted on experimental bioreactors worldwide. Finally, the hydraulic characterization of waste is discussed with regard to the evaluation of effective porosity and permeability.

  12. Dirac oscillator interacting with a topological defect

    SciTech Connect (OSTI)

    Carvalho, J.; Furtado, C.; Moraes, F. [Unidade Academica de Tecnologia de Alimentos, CCTA, Universidade Federal de Campina Grande, Pereiros, 58840-000, Pombal, Paraiba (Brazil); Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, Paraiba (Brazil)

    2011-09-15T23:59:59.000Z

    In this work we study the interaction problem of a Dirac oscillator with gravitational fields produced by topological defects. The energy levels of the relativistic oscillator in the cosmic string and in the cosmic dislocation space-times are sensible to curvature and torsion associated to these defects and are important evidence of the influence of the topology on this system. In the presence of a localized magnetic field the energy levels acquire a term associated with the Aharonov-Bohm effect. We obtain the eigenfunctions and eigenvalues and see that in the nonrelativistic limit some results known in standard quantum mechanics are reached.

  13. Modelling of thermo-mechanical and irradiation behavior of metallic and oxide fuels for sodium fast reactors

    E-Print Network [OSTI]

    Karahan, Aydin

    2009-01-01T23:59:59.000Z

    A robust and reliable code to model the irradiation behavior of metal and oxide fuels in sodium cooled fast reactors is developed. Modeling capability was enhanced by adopting a non-empirical mechanistic approach to the ...

  14. Affine Defects and Gravitation

    E-Print Network [OSTI]

    R. J. Petti

    2014-12-12T23:59:59.000Z

    We argue that the structure general relativity (GR) as a theory of affine defects is deeper than the standard interpretation as a metric theory of gravitation. Einstein-Cartan theory (EC), with its inhomogenous affine symmetry, should be the standard-bearer for GR-like theories. A discrete affine interpretation of EC (and gauge theory) yields topological definitions of momentum and spin (and Yang Mills current), and their conservation laws become discrete topological identities. Considerations from quantum theory provide evidence that discrete affine defects are the physical foundation for gravitation.

  15. Discrete torsion defects

    E-Print Network [OSTI]

    Ilka Brunner; Nils Carqueville; Daniel Plencner

    2014-09-15T23:59:59.000Z

    Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories. In the case of Landau-Ginzburg models only the bulk sector had been studied previously, and we re-derive all known results. We also introduce the notion of `projective matrix factorisations', show how they naturally describe boundary and defect sectors, and we further illustrate the efficiency of the defect-based approach by explicitly computing RR charges. Roughly half of our results are not restricted to Landau-Ginzburg models but hold more generally, for any topological field theory. In particular we prove that for a pivotal bicategory, any two objects of its orbifold completion that have the same base are orbifold equivalent. Equivalently, from any orbifold theory (including those based on nonabelian groups) the original unorbifolded theory can be obtained by orbifolding via the `quantum symmetry defect'.

  16. Evolution of Frictional Behavior of Punchbowl Fault Gouges Sheared at Seismic Slip Rates and Mechanical and Hydraulic Properties of Nankai Trough Accretionary Prism Sediments Deformed at Different Loading Paths

    E-Print Network [OSTI]

    Kitajima, Hiroko

    2012-02-14T23:59:59.000Z

    of frictional heating, mechanical behavior, and microstructure evolution? by Hiroko Kitajima, Judith S. Chester, Frederick M. Chester, and Toshihiko Shimamoto, 2010. Journal of Geophysical Research, 115, B08408, doi:10.1029/2009JB0 07038, Copyright 2010...

  17. Mayne, P.W., Coop, M.R., Springman, S., Huang, A-B., and Zornberg, J. (2009). State-of-the-Art Paper (SOA-1): GeoMaterial Behavior and Testing. Proc. 17th Intl. Conf. Soil Mechanics & Geotechnical

    E-Print Network [OSTI]

    Mayne, Paul W.

    Mayne, P.W., Coop, M.R., Springman, S., Huang, A-B., and Zornberg, J. (2009). State-of-the-Art Paper (SOA-1): GeoMaterial Behavior and Testing. Proc. 17th Intl. Conf. Soil Mechanics & Geotechnical

  18. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Coupling of Mechanical Behavior of Cell Components

    E-Print Network [OSTI]

    and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Coupling of Mechanical Behavior is to make the models compatible with CAEBAT-1 and its Open Architecture Software (OAS) for wider

  19. Microstructural Characterization of the Chemo-mechanical Behavior of Asphalt in Terms of Aging and Fatigue Performance Properties

    E-Print Network [OSTI]

    Allen, Robert Grover

    2013-03-27T23:59:59.000Z

    The study of asphalt chemo-mechanics requires a basic understanding of the physical properties and chemical composition of asphalt and how these properties are linked to changes in performance induced by chemical modifications. This work uniquely...

  20. Electron tomography of defects

    E-Print Network [OSTI]

    Sharp, Joanne

    2010-10-12T23:59:59.000Z

    . . . . . . . . . . . . . . . . . . . 36 2.6 Limitations of electron tomography . . . . . . . . . . . . . . . 37 2.6.1 The missing wedge . . . . . . . . . . . . . . . . . . . . 37 2.6.2 Minimum reliable spacing of features . . . . . . . . . . 39 3 Tomography of dislocations using weak... ELECTRON TOMOGRAPHY OF DEFECTS This dissertation is submitted for the degree of Doctor of Philosophy by Joanne Sharp Of Wolfson College Submitted 26th April 2010 Acknowledgements This dissertation is the result of my own work and includes nothing...

  1. Defect mapping system

    DOE Patents [OSTI]

    Sopori, B.L.

    1995-04-11T23:59:59.000Z

    Apparatus for detecting and mapping defects in the surfaces of polycrystalline materials in a manner that distinguishes dislocation pits from grain boundaries includes a laser for illuminating a wide spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface. An X-Y translation stage for mounting the polycrystalline material and signal processing and computer equipment accommodate rastor mapping, recording, and displaying of respective dislocation and grain boundary defect densities. A special etch procedure is included, which prepares the polycrystalline material surface to produce distinguishable intermediate and near specular light scattering in patterns that have statistical relevance to the dislocation and grain boundary defect densities. 20 figures.

  2. Application of the multi-mechanism deformation model for three-dimensional simulations of salt : behavior for the strategic petroleum reserve.

    SciTech Connect (OSTI)

    Ehgartner, Brian L.; Sobolik, Steven Ronald; Bean, James E.

    2010-07-01T23:59:59.000Z

    The U.S. Strategic Petroleum Reserve stores crude oil in 62 solution-mined caverns in salt domes located in Texas and Louisiana. Historically, three-dimensional geomechanical simulations of the behavior of the caverns have been performed using a power law creep model. Using this method, and calibrating the creep coefficient to field data such as cavern closure and surface subsidence, has produced varying degrees of agreement with observed phenomena. However, as new salt dome locations are considered for oil storage facilities, pre-construction geomechanical analyses are required that need site-specific parameters developed from laboratory data obtained from core samples. The multi-mechanism deformation (M-D) model is a rigorous mathematical description of both transient and steady-state creep phenomena. Recent enhancements to the numerical integration algorithm within the model have created a more numerically stable implementation of the M-D model. This report presents computational analyses to compare the results of predictions of the geomechanical behavior at the West Hackberry SPR site using both models. The recently-published results using the power law creep model produced excellent agreement with an extensive set of field data. The M-D model results show similar agreement using parameters developed directly from laboratory data. It is also used to predict the behavior for the construction and operation of oil storage caverns at a new site, to identify potential problems before a final cavern layout is designed.

  3. Microstructural development and mechanical behavior of eutectic bismuth-tin and eutectic indium-tin in response to high temperature deformation

    SciTech Connect (OSTI)

    Goldstein, J.L.F. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering; [Lawrence Berkeley Lab., CA (United States)

    1993-11-01T23:59:59.000Z

    The mechanical behavior and microstructure of eutectic Bi-Sn and In-Sn solders were studied in parallel in order to better understand high temperature deformation of these alloys. Bi-Sn solder joints were made with Cu substrates, and In-Sn joints were made with either Cu or Ni substrates. The as-cast microstructure of Bi-Sn is complex regular, with the two eutectic phases interconnected in complicated patterns. The as-cast microstructure of In-Sn depends on the substrate. In-Sn on Cu has a non-uniform microstructure caused by diffusion of Cu into the solder during sample preparation, with regions of the Sn-rich {gamma} phase imbedded in a matrix of the In-rich {beta} phase. The microstructure of In-Sn on Ni is uniform and lamellar and the two phases are strongly coupled. The solders deform non-uniformly, with deformation concentrating in a band along the length of the sample for Bi-Sn and In-Sn on Cu, though the deformation is more diffuse in In-Sn than in Bi-Sn. Deformation of In-Sn on Ni spreads throughout the width of the joint. The different deformation patterns affect the shape of the stress-strain curves. Stress-strain curves for Bi-Sn and In-Sn on Cu exhibit sharp decays in the engineering stress after reaching a peak. Most of this stress decay is removed for In-Sn on Ni. The creep behavior of In-Sn also depends on the substrate, with the creep deformation controlled by the soft P phase of the eutectic for In-Sn on Cu and controlled by the harder {gamma} phase for In-Sn on Ni. When In-Sn on Ni samples are aged, the microstructure coarsens and changes to an array of {gamma} phase regions in a matrix of the {beta} phase, and the creep behavior changes to resemble that of In-Sn on Cu. The creep behavior of Bi-Sn changes with temperature. Two independent mechanisms operate at lower temperatures, but there is still some question as to whether one or both of these, or a third mechanism, operates at higher temperatures.

  4. Role of defects in III-nitride based electronics

    SciTech Connect (OSTI)

    HAN,JUNG; MYERS JR.,SAMUEL M.; FOLLSTAEDT,DAVID M.; WRIGHT,ALAN F.; CRAWFORD,MARY H.; LEE,STEPHEN R.; SEAGER,CARLETON H.; SHUL,RANDY J.; BACA,ALBERT G.

    2000-01-01T23:59:59.000Z

    The LDRD entitled ``Role of Defects in III-Nitride Based Devices'' is aimed to place Sandia National Laboratory at the forefront of the field of GaN materials and devices by establishing a scientific foundation in areas such as material growth, defect characterization/modeling, and processing (metalization and etching) chemistry. In this SAND report the authors summarize their studies such as (1) the MOCVD growth and doping of GaN and AlGaN, (2) the characterization and modeling of hydrogen in GaN, including its bonding, diffusion, and activation behaviors, (3) the calculation of energetic of various defects including planar stacking faults, threading dislocations, and point defects in GaN, and (4) dry etching (plasma etching) of GaN (n- and p-types) and AlGaN. The result of the first AlGaN/GaN heterojunction bipolar transistor is also presented.

  5. Review on the effects of hydrogen at extreme pressures and temperatures on the mechanical behavior of polymers.

    SciTech Connect (OSTI)

    Hecht, Ethan S.

    2013-03-01T23:59:59.000Z

    The effects of hydrogen on the mechanics (e.g. strength, ductility, and fatigue resistance) of polymer materials are outlined in this report. There are a small number of studies reported in the literature on this topic, and even fewer at the extreme temperatures to which hydrogen service materials will be exposed. Several studies found little evidence that hydrogen affects the static tensile properties, long term creep, or ductile fracture of high density polyethylene or polyamide. However, there has been a report that a recoverable drop in the modulus of high density polyethylene is observable under high hydrogen pressure. A research need exists on the mechanical effects of hydrogen on the wide range of polymers used or considered for use in the hydrogen economy, due to the lack of data in the literature.

  6. Transmissive optomechanical platforms with engineered spatial defects

    E-Print Network [OSTI]

    Edoardo Tignone; Guido Pupillo; Claudiu Genes

    2014-06-23T23:59:59.000Z

    We investigate the optomechanical photon-phonon coupling of a single light mode propagating through an array of vibrating mechanical elements. As recently shown for the particular case of a periodic array of membranes embedded in a high-finesse optical cavity [A. Xuereb, C. Genes and A. Dantan, Phys. Rev. Lett., \\textbf{109}, 223601, (2012)], the intracavity linear optomechanical coupling can be considerably enhanced over the single element value in the so-called \\textit{transmissive regime}, where for motionless membranes the whole system is transparent to light. Here, we extend these investigations to quasi-periodic arrays in the presence of engineered spatial defects in the membrane positions. In particular we show that the localization of light modes induced by the defect combined with the access of the transmissive regime window can lead to additional enhancement of the strength of both linear and quadratic optomechanical couplings.

  7. Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

    SciTech Connect (OSTI)

    Mostaed, A., E-mail: alimostaed@yahoo.com [Advanced Materials and Nanotechnology Research Center, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, 16765-3381 Pardis Street, Tehran (Iran, Islamic Republic of); Saghafian, H.; Mostaed, E. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, 16846-13114 Narmak, Tehran (Iran, Islamic Republic of); Shokuhfar, A. [Advanced Materials and Nanotechnology Research Center, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, 16765-3381 Pardis Street, Tehran (Iran, Islamic Republic of); Rezaie, H.R. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, 16846-13114 Narmak, Tehran (Iran, Islamic Republic of)

    2013-02-15T23:59:59.000Z

    The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal, the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ? HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ? TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ? SiC particles enhance alloying process more than the TiC ones at the final stages of MM.

  8. The influence of fiber/matrix interface on the mechanical behavior of Nicalon SiC fiber reinforced glass-ceramic composites

    SciTech Connect (OSTI)

    Liu, Y.M.; Mitchell, T.E. [Los Alamos National Lab., NM (United States); Wadley, H.N.G. [Virginia Univ., Charlottesville, VA (United States). Dept. of Materials Science and Engineering

    1996-11-01T23:59:59.000Z

    Mechanical properties of unidirectional Nicalon SiC fiber reinforced Ca aluminosilicate (CAS/SiC) and Mg aluminosilicate (MAS/SiC) glass-ceramic composites were investigated by tensile testing and nondestructive laser-ultrasound technique. The Ba-stuffed MAS was either undoped or doped with 5% borosilicate glass. Degradation of elastic stiffness constant C{sub 11} in transverse direction due to interface damage was monitored in situ by measuring the laser- generated ultrasound wave velocity. The three composite materials show different characteristics of macroscopic deformation behavior, which is correlated strongly to interface degradation. A stronger reduction trend of the elastic constant C{sub 11} is associated with a larger degree of inelastic deformation. The fracture surfaces also reveal the close relation between fiber pullout length and interfacial characteristics. Interfaces of these composites were studied by TEM; their influence on inhibiting and deflecting matrix cracks is discussed.

  9. Behavior of passaged chondrocytes in collagen-glycosaminoglycan scaffolds : effects of cross-linking, mechanical loading, and genetic modification of the scaffold

    E-Print Network [OSTI]

    Lee, Cynthia R. (Cynthia Renee), 1975-

    2002-01-01T23:59:59.000Z

    Tissue engineering is a promising solution to the problematic healing of cartilage defects. The purpose of this thesis was to establish a foundation for the development of a collagen-glycosaminoglycan (CG) scaffold for ...

  10. Constitutive Model for the Time-Dependent Mechanical Behavior of 430 Stainless Steel and FeCrAlY Foams in Sulfur-Bearing Environments

    SciTech Connect (OSTI)

    Hemrick, James Gordon [ORNL; Lara-Curzio, Edgar [ORNL

    2013-01-01T23:59:59.000Z

    The mechanical behavior of 430 stainless steel and pre-oxidized FeCrAlY open-cell foam materials of various densities was evaluated in compression at temperatures between 450 C and 600 C in an environment containing hydrogen sulfide and water vapor. Both materials showed negligible corrosion due to the gaseous atmosphere for up to 168 hours. The monotonic stress-strain response of these materials was found to be dependent on both the strain rate and their density, and the 430 stainless steel foam materials exhibited less stress relaxation than FeCrAlY for similar experimental conditions. Using the results from multiple hardening-relaxation and monotonic tests, an empirical constitutive equation was derived to predict the stress-strain behavior of FeCrAlY foams as a function of temperature and strain rate. These results are discussed in the context of using these materials in a black liquor gasifier to accommodate the chemical expansion of the refractory liner resulting from its reaction with the soda in the black liquor.

  11. Intrinsic Nanoscience of ? Pu-Ga Alloys: Local Structure and Speciation, Collective Behavior, Nanoscale Heterogeneity, and Aging Mechanisms

    SciTech Connect (OSTI)

    Conradson, Steven D.; Bock, Nicolas; Castro, Julio M.; Conradson, Dylan R.; Cox, Lawrence E.; Dmowski, Wojtek; Dooley, David E.; Egami, Takeshi; Espinosa-Faller, Francisco J.; Freibert, Franz J.; Garcia-Adeva, Angel J.; Hess, Nancy J.; Holmstrom, Erik; Howell, Rafael C.; Katz, Barbara A.; Lashley, Jason C.; Martinez, Raymond J.; Moore, David P.; Morales, Luis A.; Olivas, J David; Pereyra, Ramiro A.; Ramos, Michael; Terry, Jeff H.; Villella, Phillip M.

    2014-04-24T23:59:59.000Z

    Because diffraction measurements are sensitive only to the long range average arrangement of the atoms in the coherent portion of a crystal, complementary local structure measurements are required for a complete understanding of the structure of a complex material. This is particularly an issue in solid solutions where even random distributions of a solute will result in nanometer-scale fluctuations in the local composition. The structure will be further complicated if collective and cooperative phenomena organize the solute distribution via longer range interactions between non-bonded solute sites. If the solute affects the phase stability then the question is raised of whether the atoms in domains with local compositions outside the limits of the bulk phase will rearrange into the structure stable for that composition and temperature or if the resulting stress would prevent such a local phase transition. If the former, then phase separated, heterogeneous structures at or below the diffraction limit will form. This nanometerscale competition between the phase transition and the epitaxial mismatch – exacerbated by the added strain if the transition involves a volume change – raises the potential for the formation of novel structures that do not occur in bulk material, e.g., fcc Fe. This coupling over multiple scales between inhomogeneity ordering, elastic forces, phase competition, and texture in the form of coexisting structures is a hallmark of martensites, a class of complex materials that includes ?-stabilized PuGa and that often exhibit correlated atomic and electronic properties. The enigmatic and extreme nature of Pu is consistent with its exhibiting unusual structural behavior of this type, including nanoscale heterogeneity in ?-stabilized PuGa and its enhanced homogeneity on aging that has been suggested based on earlier X-ray Absorption Fine Structure (XAFS) spectroscopy and x-ray pair distribution function (pdf) measurements. Measurements on a defined set of laboratory-prepared materials now corroborate and better describe this heterogeneity while additional aged samples demonstrate the role of heterogeneity in aging processes in Pu.

  12. The effect of magnetic field on bistability in 1D photonic crystal doped by magnetized plasma and coupled nonlinear defects

    SciTech Connect (OSTI)

    Mehdian, H.; Mohammadzahery, Z.; Hasanbeigi, A. [Department of Physics and Institute for Plasma Research, Kharazmi University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)] [Department of Physics and Institute for Plasma Research, Kharazmi University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

    2014-01-15T23:59:59.000Z

    In this work, we study the defect mode and bistability behavior of 1-D photonic band gap structure with magnetized plasma and coupled nonlinear defects. The transfer matrix method has been employed to investigate the magnetic field effect on defect mode frequency and bistability threshold. The obtained results show that the frequency of defect mode and bistability threshold can be altered, without changing the structure of the photonic multilayer. Therefore, the bistability behavior of the subjected structure in the presence of magnetized plasma can be utilized in manufacturing wide frequency range devices.

  13. FRAPCON-2: A Computer Code for the Calculation of Steady State Thermal-Mechanical Behavior of Oxide Fuel Rods

    SciTech Connect (OSTI)

    Berna, G. A; Bohn, M. P.; Rausch, W. N.; Williford, R. E.; Lanning, D. D.

    1981-01-01T23:59:59.000Z

    FRAPCON-2 is a FORTRAN IV computer code that calculates the steady state response of light Mater reactor fuel rods during long-term burnup. The code calculates the temperature, pressure, deformation, and tai lure histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include (a) heat conduction through the fuel and cladding, (b) cladding elastic and plastic deformation, (c) fuel-cladding mechanical interaction, (d) fission gas release, (e} fuel rod internal gas pressure, (f) heat transfer between fuel and cladding, (g) cladding oxidation, and (h) heat transfer from cladding to coolant. The code contains necessary material properties, water properties, and heat transfer correlations. FRAPCON-2 is programmed for use on the CDC Cyber 175 and 176 computers. The FRAPCON-2 code Is designed to generate initial conditions for transient fuel rod analysis by either the FRAP-T6 computer code or the thermal-hydraulic code, RELAP4/MOD7 Version 2.

  14. Crystallization Behavior of Virgin TR-55 Silicone Rubber Measured Using Dynamic Mechanical Thermal Analysis with Liquid Nitrogen Cooling

    SciTech Connect (OSTI)

    Small IV, W; Wilson, T S

    2010-02-11T23:59:59.000Z

    Dynamic mechanical thermal analysis (DMTA) of virgin TR-55 silicone rubber specimens was conducted. Two dynamic temperature sweep tests, 25 to -100 C and 25 to -70 to 0 C (ramp rate = 1 C/min), were conducted at a frequency of 6.28 rad/s (1 Hz) using a torsion rectangular test geometry. A strain of 0.1% was used, which was near the upper limit of the linear viscoelastic region of the material based on an initial dynamic strain sweep test. Storage (G{prime}) and loss (G{double_prime}) moduli, the ratio G{double_prime}/G{prime} (tan {delta}), and the coefficient of linear thermal expansion ({alpha}) were determined as a function of temperature. Crystallization occurred between -40 and -60 C, with G{prime} increasing from {approx}6 x 10{sup 6} to {approx}4 x 10{sup 8} Pa. The value of {alpha} was fairly constant before ({approx}4 x 10{sup -4} mm/mm- C) and after ({approx}3 x 10{sup -4} mm/mm- C) the transition, and peaked during the transition ({approx}3 x 10{sup -3} mm/mm- C). Melting occurred around -30 C upon heating.

  15. Flow in porous media, phase behavior and ultralow interfacial tensions: mechanisms of enhanced petroleum recovery. Final technical report

    SciTech Connect (OSTI)

    Davis, H.T.; Scriven, L.E.

    1982-01-01T23:59:59.000Z

    A major program of university research, longer-ranged and more fundamental in approach than industrial research, into basic mechanisms of enhancing petroleum recovery and into underlying physics, chemistry, geology, applied mathematics, computation, and engineering science has been built at Minnesota. The 1982 outputs of the interdisciplinary team of investigators were again ideas, instruments, techniques, data, understanding and skilled people: forty-one scientific and engineering papers in leading journals; four pioneering Ph.D. theses; numerous presentations to scientific and technical meetings, and to industrial, governmental and university laboratories; vigorous program of research visits to and from Minnesota; and two outstanding Ph.D.'s to research positions in the petroleum industry, one to a university faculty position, one to research leadership in a governmental institute. This report summarizes the 1982 papers and theses and features sixteen major accomplishments of the program during that year. Abstracts of all forty-five publications in the permanent literature are appended. Further details of information transfer and personnel exchange with industrial, governmental and university laboratories appear in 1982 Quarterly Reports available from the Department of Energy and are not reproduced here. The Minnesota program continues in 1983, notwithstanding earlier uncertainty about the DOE funding which finally materialized and is the bulk of support. Supplemental grants-in-aid from nine companies in the petroleum industry are important, as are the limited University and departmental contributions. 839 references, 172 figures, 29 tables.

  16. Transformation behavior and shape memory characteristics of thermo-mechanically treated Ti–(45?x)Ni–5Cu–xV (at%) alloys

    SciTech Connect (OSTI)

    Jang, Jae-young; Chun, Su-jin [Division of Materials Scince and Engineering and ERI, Gyeongsang National University, 501 Jinjudaero, Jinju, Gyeongnam 660-701 (Korea, Republic of)] [Division of Materials Scince and Engineering and ERI, Gyeongsang National University, 501 Jinjudaero, Jinju, Gyeongnam 660-701 (Korea, Republic of); Choi, Eunsoo [Department of Civil Engineering, Hongik University, Seoul (Korea, Republic of)] [Department of Civil Engineering, Hongik University, Seoul (Korea, Republic of); Liu, Yinong; Yang, Hong [School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)] [School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [Division of Materials Scince and Engineering and ERI, Gyeongsang National University, 501 Jinjudaero, Jinju, Gyeongnam 660-701 (Korea, Republic of)] [Division of Materials Scince and Engineering and ERI, Gyeongsang National University, 501 Jinjudaero, Jinju, Gyeongnam 660-701 (Korea, Republic of)

    2012-10-15T23:59:59.000Z

    Transformation behavior, shape memory characteristics and superelasticity of thermo-mechanically treated Ti–(45?x)Ni–5Cu–xV (at%) (x = 0.5–2.0) alloys were investigated by means of differential scanning calorimetry, transmission electron microscopy, X-ray diffractions, thermal cycling tests under constant load and tensile tests. The B2–B19? transformation occurred when V content was 0.5 at%, above which the B2–B19–B19? transformation occurred. The B2–B19 transformation was not separated clearly from the B19–B19? transformation. Thermo-mechanically treated Ti–(45?x)Ni–5Cu–xV alloys showed perfect shape memory effect and transformation hysteresis(?T) of Ti–43.5Ni–5.0Cu–1.5V and Ti–43.0Ni–5.0Cu–2.0V alloys was about 9 K which was much smaller than that of a Ti–44.5Ni–5.0Cu–0.5V alloy(23.3 K). More than 90% of superelastic recovery ratio was observed in all specimens and transformation hysteresis (??) of a Ti–44.5Ni–5.0Cu–0.5V alloy was about 70 MPa, which was much larger than that of a Ti–43.0Ni–5.0Cu–2.0V alloy (35 MPa).

  17. Positive muon and the positron as probes of defects

    SciTech Connect (OSTI)

    Lynn, K G

    1980-01-01T23:59:59.000Z

    The positive muon and the positron are each being used nowadays to investigate defects in condensed matter. A brief summary of the experimental methods employed with each particle is given in this paper. Similarities and differences between the behavior of the two leptons when implanted in consensed matter are pointed out, and by means of a comparison between muon and positron data in Al it is shown that the combination of muon and positron experiments can serve as a useful new probe of defects in solids.

  18. 3.22 Mechanical Properties of Materials, Spring 2003

    E-Print Network [OSTI]

    Gibson, Lorna J.

    Phenomenology of mechanical behavior of materials at the macroscopic level. Relationship of mechanical behavior to material structure and mechanisms of deformation and failure. Topics include: elasticity, viscoelasticity, ...

  19. Energy Dissipation and Defect Generation for Nanocrystalline...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defect Generation for Nanocrystalline Silicon Carbide. Abstract: Large-scale molecular dynamics simulations have been employed to study defect generation and primary damage...

  20. Gradient Improvement by Removal of Identified Local Defects

    SciTech Connect (OSTI)

    R.L. Geng, W.A. Clemens, C.A. Cooper, H. Hayano, K. Watanabe

    2011-07-01T23:59:59.000Z

    Recent experience of ILC cavity processing and testing at Jefferson Lab has shown that some 9-cell cavities are quench limited at a gradient in the range of 15-25 MV/m. Further studies reveal that these quench limits are often correlated with sub-mm sized and highly localized geometrical defects at or near the equator weld. There are increasing evidence to show that these genetic defects have their origin in the material or in the electron beam welding process (for example due to weld irregularities or splatters on the RF surface and welding porosity underneath the surface). A local defect removal method has been proposed at Jefferson Lab by locally re-melting the niobium material. Several 1-cell cavities with known local defects have been treated by using the JLab local e-beam re-melting method, resulting in gradient and Q0 improvement. We also sent 9-cell cavities with known gradient limiting local defects to KEK for local grinding and to FNAL for global mechanical polishing. We report on the results of gradient improvements by removal of local defects in these cavities.

  1. Density of defects and the scaling law of the entanglement entropy in quantum phase transition of one dimensional spin systems induced by a quench

    E-Print Network [OSTI]

    Banasri Basu; Pratul Bandyopadhyay; Priyadarshi Majumdar

    2011-03-07T23:59:59.000Z

    We have studied quantum phase transition induced by a quench in different one dimensional spin systems. Our analysis is based on the dynamical mechanism which envisages nonadiabaticity in the vicinity of the critical point. This causes spin fluctuation which leads to the random fluctuation of the Berry phase factor acquired by a spin state when the ground state of the system evolves in a closed path. The two-point correlation of this phase factor is associated with the probability of the formation of defects. In this framework, we have estimated the density of defects produced in several one dimensional spin chains. At the critical region, the entanglement entropy of a block of $L$ spins with the rest of the system is also estimated which is found to increase logarithmically with $L$. The dependence on the quench time puts a constraint on the block size $L$. It is also pointed out that the Lipkin-Meshkov-Glick model in point-splitting regularized form appears as a combination of the XXX model and Ising model with magnetic field in the negative z-axis. This unveils the underlying conformal symmetry at criticality which is lost in the sharp point limit. Our analysis shows that the density of defects as well as the scaling behavior of the entanglement entropy follows a universal behavior in all these systems.

  2. Density of defects and the scaling law of the entanglement entropy in quantum phase transition of one-dimensional spin systems induced by a quench

    SciTech Connect (OSTI)

    Basu, Banasri; Bandyopadhyay, Pratul; Majumdar, Priyadarshi [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700 108 (India); Jyotinagar Bidyasree Niketan H.S. School, 41 Jyotinagar, Kolkata 700 108 (India)

    2011-03-15T23:59:59.000Z

    We have studied quantum phase transition induced by a quench in different one-dimensional spin systems. Our analysis is based on the dynamical mechanism which envisages nonadiabaticity in the vicinity of the critical point. This causes spin fluctuation which leads to the random fluctuation of the Berry phase factor acquired by a spin state when the ground state of the system evolves in a closed path. The two-point correlation of this phase factor is associated with the probability of the formation of defects. In this framework, we have estimated the density of defects produced in several one-dimensional spin chains. At the critical region, the entanglement entropy of a block of L spins with the rest of the system is also estimated which is found to increase logarithmically with L. The dependence on the quench time puts a constraint on the block size L. It is also pointed out that the Lipkin-Meshkov-Glick model in point-splitting regularized form appears as a combination of the XXX model and Ising model with magnetic field in the negative z axis. This unveils the underlying conformal symmetry at criticality which is lost in the sharp point limit. Our analysis shows that the density of defects as well as the scaling behavior of the entanglement entropy follows a universal behavior in all these systems.

  3. 6When you heat a rubber band, it contracts. If you only know about point particles and ideal gases, this behavior is perplexing. But, a simple classical statistical mechanics model of a chain

    E-Print Network [OSTI]

    Ha, Taekjip

    gases, this behavior is perplexing. But, a simple classical statistical mechanics model of a chain for given N and M. Call the result (N,M). (b) Using Stirling's approximation in the form ln(N!) N ln(N) - N and extent R, in the regime Na >> R. Write down the expression for the free energy of the chain (in

  4. Topological Defects from the Multiverse

    E-Print Network [OSTI]

    Zhang, Jun; Garriga, Jaume; Vilenkin, Alexander

    2015-01-01T23:59:59.000Z

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly e...

  5. Topological Defects from the Multiverse

    E-Print Network [OSTI]

    Jun Zhang; Jose J. Blanco-Pillado; Jaume Garriga; Alexander Vilenkin

    2015-01-22T23:59:59.000Z

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  6. animal behavior: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    behavior Describe the basic features of the scientific method and describe forms of energy in the context of behavior (radiant, chemical, mechanical, electrical behaviors. Know...

  7. Mechanical behavior of ultrastructural biocomposites

    E-Print Network [OSTI]

    Kearney, Cathal (Cathal John)

    2006-01-01T23:59:59.000Z

    For numerous centuries nature has successfully developed biocomposite materials with detailed multiscale architectures to provide a material stiffness, strength and toughness. One such example is nacre, which is found in ...

  8. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Indium Under the Nanoscope In this work, Lee et al. investigated the small-scale plastic deformation of indium nanopillars, a previously unstudied material and crystal...

  9. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHighand Retrievals from a NewCuneo Matthew1,

  10. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your Home andDisposition |MaterialsMatt10Laser,Measuring

  11. Mechanical Behavior of Indium Nanostructures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your Home andDisposition

  12. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    SciTech Connect (OSTI)

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01T23:59:59.000Z

    Accurately estimating tritium retention in plasma facing components (PFCs) and minimizing its uncertainty are key safety issues for licensing future fusion power reactors. D-T fusion reactions produce 14.1 MeV neutrons that activate PFCs and create radiation defects throughout the bulk of the material of these components. Recent studies show that tritium migrates and is trapped in bulk (>> 10 µm) tungsten beyond the detection range of nuclear reaction analysis technique [1-2], and thermal desorption spectroscopy (TDS) technique becomes the only established diagnostic that can reveal hydrogen isotope behavior in in bulk (>> 10 µm) tungsten. Radiation damage and its recovery mechanisms in neutron-irradiated tungsten are still poorly understood, and neutron-irradiation data of tungsten is very limited. In this paper, systematic investigations with repeated plasma exposures and thermal desorption are performed to study defect annealing and thermal desorption of deuterium in low dose neutron-irradiated tungsten. Three tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to high flux (ion flux of (0.5-1.0)x1022 m-2s-1 and ion fluence of 1x1026 m-2) deuterium plasma at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy (TDS) was performed with a ramp rate of 10 °C/min up to 900 °C, and the samples were annealed at 900 °C for 0.5 hour. These procedures were repeated three (for 100 and 200 °C samples) and four (for 500 °C sample) times to uncover damage recovery mechanisms and its effects on deuterium behavior. The results show that deuterium retention decreases approximately 90, 75, and 66 % for 100, 200, and 500 °C, respectively after each annealing. When subjected to the same TDS recipe, the desorption temperature shifts from 800 °C to 600 °C after 1st annealing for the sample exposed to TPE at 500 °C. Tritium Migration Analysis Program (TMAP) analysis reveals that the detrapping energy decreases from 1.8 eV to 1.4 eV, indicating the changes in trapping mechanisms. This paper also summarizes deuterium behavior studies in HFIR neutron-irradiated tungsten under US-Japan TITAN program.

  13. Apparatus and method for defect testing of integrated circuits

    SciTech Connect (OSTI)

    Cole, E.I. Jr.; Soden, J.M.

    2000-02-29T23:59:59.000Z

    An apparatus and method for defect and failure-mechanism testing of integrated circuits (ICs) is disclosed. The apparatus provides an operating voltage, V(DD), to an IC under test and measures a transient voltage component, V(DDT), signal that is produced in response to switching transients that occur as test vectors are provided as inputs to the IC. The amplitude or time delay of the V(DDT) signal can be used to distinguish between defective and defect-free (i.e. known good) ICs. The V(DDT) signal is measured with a transient digitizer, a digital oscilloscope, or with an IC tester that is also used to input the test vectors to the IC. The present invention has applications for IC process development, for the testing of ICs during manufacture, and for qualifying ICs for reliability.

  14. Apparatus and method for defect testing of integrated circuits

    DOE Patents [OSTI]

    Cole, Jr., Edward I. (Albuquerque, NM); Soden, Jerry M. (Placitas, NM)

    2000-01-01T23:59:59.000Z

    An apparatus and method for defect and failure-mechanism testing of integrated circuits (ICs) is disclosed. The apparatus provides an operating voltage, V.sub.DD, to an IC under test and measures a transient voltage component, V.sub.DDT, signal that is produced in response to switching transients that occur as test vectors are provided as inputs to the IC. The amplitude or time delay of the V.sub.DDT signal can be used to distinguish between defective and defect-free (i.e. known good) ICs. The V.sub.DDT signal is measured with a transient digitizer, a digital oscilloscope, or with an IC tester that is also used to input the test vectors to the IC. The present invention has applications for IC process development, for the testing of ICs during manufacture, and for qualifying ICs for reliability.

  15. Structure, defects, and strain in silicon-silicon oxide interfaces

    SciTech Connect (OSTI)

    Kova?evi?, Goran, E-mail: gkova@irb.hr; Pivac, Branko [Department of Materials Physics, Rudjer Boskovic Institute, Bijeni?ka 56, P.O.B. 180, HR-10002 Zagreb (Croatia)

    2014-01-28T23:59:59.000Z

    The structure of the interfaces between silicon and silicon-oxide is responsible for proper functioning of MOSFET devices while defects in the interface can deteriorate this function and lead to their failure. In this paper we modeled this interface and characterized its defects and strain. MD simulations were used for reconstructing interfaces into a thermodynamically stable configuration. In all modeled interfaces, defects were found in the form of three-coordinated silicon atom, five coordinated silicon atom, threefold-coordinated oxygen atom, or displaced oxygen atom. Three-coordinated oxygen atom can be created if dangling bonds on silicon are close enough. The structure and stability of three-coordinated silicon atoms (P{sub b} defect) depend on the charge as well as on the electric field across the interface. The negatively charged P{sub b} defect is the most stable one, but the electric field resulting from the interface reduces that stability. Interfaces with large differences in periodic constants of silicon and silicon oxide can be stabilized by buckling of silicon layer. The mechanical stress resulted from the interface between silicon and silicon oxide is greater in the silicon oxide layer. Ab initio modeling of clusters representing silicon and silicon oxide shows about three time larger susceptibility to strain in silicon oxide than in silicon if exposed to the same deformation.

  16. An investigation of defect detection using random defect excitation and deterministic defect observation in complex integrated logic circuits

    E-Print Network [OSTI]

    Dworak, Jennifer

    2013-02-22T23:59:59.000Z

    aWhenever integrated circuits are manufactured, a certain percentage of those circuits will be defective. Defective circuits present problems for both the manufacturers who wish to maintain a good reputation with their customers and the consumers...

  17. MESOSCALE DESCRIPTION OF DEFECTED MATERIALS

    E-Print Network [OSTI]

    Vinals, Jorge

    MESOSCALE DESCRIPTION OF DEFECTED MATERIALS Jorge Vi~nals School of Physics and Astronomy. Laughlin) Small but finite wavenumber and finite frequency ("mesoscale") response functions and transport;MESOSCALE DESCRIPTION B B B B B B B A B A B A A B B A A A A BB A B Microscopic Mesoscopic Macroscopic vn

  18. Scratch behavior of polymers

    E-Print Network [OSTI]

    Lim, Goy Teck

    2005-11-01T23:59:59.000Z

    of the generated results that a good understanding can be gained on how different scratch conditions can affect scratch behavior of PP. A phenomenological deduction of the scratch damage process and mechanisms is also established. Considering the two main damage...

  19. The relationship between grain boundary structure, defect mobility, and grain boundary sink efficiency

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Uberuaga, Blas Pedro; Vernon, Louis J.; Martinez, Enrique; Voter, Arthur F.

    2015-03-13T23:59:59.000Z

    Nanocrystalline materials have received great attention due to their potential for improved functionality and have been proposed for extreme environments where the interfaces are expected to promote radiation tolerance. However, the precise role of the interfaces in modifying defect behavior is unclear. Using long-time simulations methods, we determine the mobility of defects and defect clusters at grain boundaries in Cu. We find that mobilities vary significantly with boundary structure and cluster size, with larger clusters exhibiting reduced mobility, and that interface sink efficiency depends on the kinetics of defects within the interface via the in-boundary annihilation rate of defects. Thus,more »sink efficiency is a strong function of defect mobility, which depends on boundary structure, a property that evolves with time. Further, defect mobility at boundaries can be slower than in the bulk, which has general implications for the properties of polycrystalline materials. Finally, we correlate defect energetics with the volumes of atomic sites at the boundary.« less

  20. Anticorrelation between Surface and Subsurface Point Defects...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    between Surface and Subsurface Point Defects and the Impact on the Redox Chemistry of TiO2(110). Anticorrelation between Surface and Subsurface Point Defects and the...

  1. Magnesium behavior and structural defects in Mg+ ion implanted...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. The...

  2. Inspection of lithographic mask blanks for defects

    DOE Patents [OSTI]

    Sommargren, Gary E. (Santa Cruz, CA)

    2001-01-01T23:59:59.000Z

    A visible light method for detecting sub-100 nm size defects on mask blanks used for lithography. By using optical heterodyne techniques, detection of the scattered light can be significantly enhanced as compared to standard intensity detection methods. The invention is useful in the inspection of super-polished surfaces for isolated surface defects or particulate contamination and in the inspection of lithographic mask or reticle blanks for surface defects or bulk defects or for surface particulate contamination.

  3. Assessment of structures and stabilities of defect clusters and surface energies predicted by nine interatomic potentials for UO2

    SciTech Connect (OSTI)

    Stephen A. Taller; Xian-Ming Bai

    2013-11-01T23:59:59.000Z

    The irradiation in nuclear reactors creates many point defects and defect clusters in uranium dioxide (UO2) and their evolution severely degrades the thermal and mechanical properties of the nuclear fuels. Previously many empirical interatomic potentials have been developed for modeling defect production and evolution in UO2. However, the properties of defect clusters and extended defects are usually not fitted into these potentials. In this work nine interatomic potentials for UO2 are examined by using molecular statics and molecular dynamics to assess their applicability in predicting the properties of various types of defect clusters in UO2. The binding energies and structures for these defect clusters have been evaluated for each potential. In addition, the surface energies of voids of different radii and (1 1 0) flat surfaces predicted by these potentials are also evaluated. It is found that both good agreement and significant discrepancies exist for these potentials in predicting these properties. For oxygen interstitial clusters, these potentials predict significantly different defect cluster structures and stabilities; For defect clusters consisting of both uranium and oxygen defects, the prediction is in better agreement; The surface energies predicted by these potentials have significant discrepancies, and some of them are much higher than the experimentally measured values. The results from this work can provide insight on interpreting the outcome of atomistic modeling of defect production using these potentials and may provide guidelines for choosing appropriate potential models to study problems of interest in UO2.

  4. Method for mask repair using defect compensation

    DOE Patents [OSTI]

    Sweeney, Donald W. (San Ramon, CA); Ray-Chaudhuri, Avijit K. (Livermore, CA)

    2001-01-01T23:59:59.000Z

    A method for repair of amplitude and/or phase defects in lithographic masks. The method involves modifying or altering a portion of the absorber pattern on the surface of the mask blank proximate to the mask defect to compensate for the local disturbance (amplitude or phase) of the optical field due to the defect.

  5. Computer code for the atomistic simulation of lattice defects and dynamics. [COMENT code

    SciTech Connect (OSTI)

    Schiffgens, J.O.; Graves, N.J.; Oster, C.A.

    1980-04-01T23:59:59.000Z

    This document has been prepared to satisfy the need for a detailed, up-to-date description of a computer code that can be used to simulate phenomena on an atomistic level. COMENT was written in FORTRAN IV and COMPASS (CDC assembly language) to solve the classical equations of motion for a large number of atoms interacting according to a given force law, and to perform the desired ancillary analysis of the resulting data. COMENT is a dual-purpose intended to describe static defect configurations as well as the detailed motion of atoms in a crystal lattice. It can be used to simulate the effect of temperature, impurities, and pre-existing defects on radiation-induced defect production mechanisms, defect migration, and defect stability.

  6. Process for rapid detection of fratricidal defects on optics using Linescan Phase Differential Imaging

    SciTech Connect (OSTI)

    Ravizza, F L; Nostrand, M C; Kegelmeyer, L M; Hawley, R A; Johnson, M A

    2009-11-05T23:59:59.000Z

    Phase-defects on optics used in high-power lasers can cause light intensification leading to laser-induced damage of downstream optics. We introduce Linescan Phase Differential Imaging (LPDI), a large-area dark-field imaging technique able to identify phase-defects in the bulk or surface of large-aperture optics with a 67 second scan-time. Potential phase-defects in the LPDI images are indentified by an image analysis code and measured with a Phase Shifting Diffraction Interferometer (PSDI). The PSDI data is used to calculate the defects potential for downstream damage using an empirical laser-damage model that incorporates a laser propagation code. A ray tracing model of LPDI was developed to enhance our understanding of its phase-defect detection mechanism and reveal limitations.

  7. Effect of implanted species on thermal evolution of ion-induced defects in ZnO

    SciTech Connect (OSTI)

    Azarov, A. Yu.; Rauwel, P.; Kuznetsov, A. Yu.; Svensson, B. G. [Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, PO Box 1048 Blindern, N-0316 Oslo (Norway); Hallén, A. [Royal Institute of Technology, KTH-ICT, Electrum 229, SE-164 40, Kista, Stockholm (Sweden); Du, X. L. [Institute of Physics, The Chinese Academy of Sciences, Beijing 100190 (China)

    2014-02-21T23:59:59.000Z

    Implanted atoms can affect the evolution of ion-induced defects in radiation hard materials exhibiting a high dynamic annealing and these processes are poorly understood. Here, we study the thermal evolution of structural defects in wurtzite ZnO samples implanted at room temperature with a wide range of ion species (from {sup 11}B to {sup 209}Bi) to ion doses up to 2?×?10{sup 16}?cm{sup ?2}. The structural disorder was characterized by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis, and transmission electron microscopy, while secondary ion mass spectrometry was used to monitor the behavior of both the implanted elements and residual impurities, such as Li. The results show that the damage formation and its thermal evolution strongly depend on the ion species. In particular, for F implanted samples, a strong out-diffusion of the implanted ions results in an efficient crystal recovery already at 600?°C, while co-implantation with B (via BF{sub 2}) ions suppresses both the F out-diffusion and the lattice recovery at such low temperatures. The damage produced by heavy ions (such as Cd, Au, and Bi) exhibits a two-stage annealing behavior where efficient removal of point defects and small defect clusters occurs at temperatures ?500?°C, while the second stage is characterized by a gradual and partial annealing of extended defects. These defects can persist even after treatment at 900?°C. In contrast, the defects produced by light and medium mass ions (O, B, and Zn) exhibit a more gradual annealing with increasing temperature without distinct stages. In addition, effects of the implanted species may lead to a nontrivial defect evolution during the annealing, with N, Ag, and Er as prime examples. In general, the obtained results are interpreted in terms of formation of different dopant-defect complexes and their thermal stability.

  8. High-field critical current enhancement by irradiation induced correlated and random defects in (Ba{sub 0.6}K{sub 0.4})Fe{sub 2}As{sub 2}

    SciTech Connect (OSTI)

    Kihlstrom, K. J.; Crabtree, G. W. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Fang, L.; Jia, Y.; Shen, B.; Koshelev, A. E.; Welp, U.; Kwok, W.-K. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kayani, A. [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008 (United States)] [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Zhu, S. F. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Wen, H.-H. [National Laboratory of Solid State Microstructures, Department of Physics, Center for Superconducting Physics and Materials, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Solid State Microstructures, Department of Physics, Center for Superconducting Physics and Materials, Nanjing University, Nanjing 210093 (China)

    2013-11-11T23:59:59.000Z

    Mixed pinning landscapes in superconductors are emerging as an effective strategy to achieve high critical currents in high, applied magnetic fields. Here, we use heavy-ion and proton irradiation to create correlated and point defects to explore the vortex pinning behavior of each and combined constituent defects in the iron-based superconductor Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} and find that the pinning mechanisms are non-additive. The major effect of p-irradiation in mixed pinning landscapes is the generation of field-independent critical currents in very high fields. At 7 T ? c and 5 K, the critical current density exceeds 5 MA/cm{sup 2}.

  9. Learning Defect Predictors:Lessons from the Trenches Learning Defect Predictors

    E-Print Network [OSTI]

    Menzies, Tim

    Learning Defect Predictors:Lessons from the Trenches Learning Defect Predictors: Lessons from the Trenches Tim Menzies LCSEE, WVU tim@menzies.us October 28, 2008 1 / 40 #12;Learning Defect Predictors:Lessons change the rules of the game. 2 / 40 #12;Learning Defect Predictors:Lessons from the Trenches

  10. Atomic Scale Details of Defect-Boundary Interactions

    E-Print Network [OSTI]

    Chen, Di

    2014-12-18T23:59:59.000Z

    consists of alternately positioned interstitials and vacancies. The subsequent defect annihilation between neighboring defects on the chain leads to the defect transport. We identify three types of defect transport models which involve different chains...

  11. Gravitational energy of conical defects

    E-Print Network [OSTI]

    J. W. Maluf; A. Kneip

    1996-08-22T23:59:59.000Z

    The energy density of asymptotically flat gravitational fields can be calculated from a simple expression involving the trace of the torsion tensor. Integration of this energy density over the whole space yields the ADM energy. Such expression can be justified within the framework of the teleparallel equivalent of general relativity, which is an alternative geometrical formulation of Einstein's general relativity. In this paper we apply this energy density to the evaluation of the energy per unit length of a class of conical defects of topological nature, which include disclinations and dislocations (in the terminology of crystallography). Disclinations correspond to cosmic strings, and for a spacetime endowed with only such a defect we obtain precisely the well known expression of energy per unit length. However for a pure spacetime dislocation the total gravitational energy is zero.

  12. Conformal nets III: fusion of defects

    E-Print Network [OSTI]

    Arthur Bartels; Christopher L. Douglas; André Henriques

    2015-02-21T23:59:59.000Z

    Conformal nets provides a mathematical model for conformal field theory. We define a notion of defect between conformal nets, formalizing the idea of an interaction between two conformal field theories. We introduce an operation of fusion of defects, and prove that the fusion of two defects is again a defect, provided the fusion occurs over a conformal net of finite index. There is a notion of sector (or bimodule) between two defects, and operations of horizontal and vertical fusion of such sectors. Our most difficult technical result is that the horizontal fusion of the vacuum sectors of two defects is isomorphic to the vacuum sector of the fused defect. Equipped with this isomorphism, we construct the basic interchange isomorphism between the horizontal fusion of two vertical fusions and the vertical fusion of two horizontal fusions of sectors.

  13. Characterization of V-shaped defects in 4H-SiC homoepitaxial layers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Lihua; Su, Dong; Kisslinger, Kim; Stach, Eric; Chung, Gil; Zhang, Jie; Thomas, Bernd; Sanchez, Edward K; Mueller, Stephan G.; Hansen, Darren; et al

    2015-05-01T23:59:59.000Z

    Synchrotron white beam x-ray topography images show that faint needle-like surface morphological features observed on the Si-face of 4H-SiC homoepitaxial layers using Nomarski optical microscopy are associated with V shaped stacking faults in the epilayer. KOH etching of the V shaped defect reveals small oval pits connected by a shallow line which corresponding to the surface intersections of two partial dislocations and the stacking fault connecting them. Transmission electron microscopy (TEM) specimens from regions containing the V shaped defects were prepared using focused ion beam milling, and stacking sequences of (85), (50) and (63) are observed at the faulted regionmore »with high resolution TEM. In order to study the formation mechanism of V shaped defect, low dislocation density 4H-SiC substrates were chosen for epitaxial growth, and the corresponding regions before and after epitaxy growth are compared in SWBXT images. It is found that no defects in the substrate are directly associated with the formation of the V shaped defect. Simulation results of the contrast from the two partial dislocations associated with V shaped defect in synchrotron monochromatic beam x-ray topography reveals the opposite sign nature of their Burgers vectors. Therefore, a mechanism of 2D nucleation during epitaxy growth is postulated for the formation of the V shaped defect, which requires elimination of non-sequential 1/4[0001] bilayers from the original structure to create the observed faulted stacking sequence.« less

  14. Graphene defect formation by extreme ultraviolet generated photoelectrons

    SciTech Connect (OSTI)

    Gao, A., E-mail: a.gao@utwente.nl; Lee, C. J.; Bijkerk, F. [FOM-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands and XUV Optics Group, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands)

    2014-08-07T23:59:59.000Z

    We have studied the effect of photoelectrons on defect formation in graphene during extreme ultraviolet (EUV) irradiation. Assuming the major role of these low energy electrons, we have mimicked the process by using low energy primary electrons. Graphene is irradiated by an electron beam with energy lower than 80?eV. After e-beam irradiation, it is found that the D peak, I(D), appears in the Raman spectrum, indicating defect formation in graphene. The evolution of I(D)/I(G) follows the amorphization trajectory with increasing irradiation dose, indicating that graphene goes through a transformation from microcrystalline to nanocrystalline and then further to amorphous carbon. Further, irradiation of graphene with increased water partial pressure does not significantly change the Raman spectra, which suggests that, in the extremely low energy range, e-beam induced chemical reactions between residual water and graphene are not the dominant mechanism driving defect formation in graphene. Single layer graphene, partially suspended over holes was irradiated with EUV radiation. By comparing with the Raman results from e-beam irradiation, it is concluded that the photoelectrons, especially those from the valence band, contribute to defect formation in graphene during irradiation.

  15. Symmetry Breaking and Topological Defect Formation in Ion Coulomb Crystals

    E-Print Network [OSTI]

    Pyka, Karsten; Partner, Heather L; Nigmatullin, Ramil; Burgermeister, Tobias; Meier, David-M; Kuhlmann, Kristijan; Retzker, Alex; Plenio, Martin B; Zurek, Wojciech H; del Campo, Adolfo; Mehlstäubler, Tanja E

    2013-01-01T23:59:59.000Z

    Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry state independently. Where such local choices are incompatible, defects will form with densities predicted to follow a power law scaling in the rate of the transition. The importance of this Kibble-Zurek mechanism (KZM) ranges from cosmology to condensed matter [1-4]. In previous tests in homogeneous systems, defect formation was seen, but weak dependence on the transition rate and limited control of external parameters so far prevented tests of KZM scaling. As recently predicted [5-9], in inhomogeneous systems propagation of the critical front enhances the role of causality and steepens scaling of defect density with the transition rate. We use ion Coulomb crystals in a harmonic trap to demonstrate, for the first time, scaling of the number of topological defects with the transition rate - the central prediction of K...

  16. http://journals.cambridge.org Downloaded: 24 Feb 2014 IP address: 128.100.48.236 Characterizing mechanical behavior of atomically thin

    E-Print Network [OSTI]

    Sun, Yu

    applications to composite materials,2­4 lubricants,5,6 electronics,7­9 batteries,10­12 optics,13,14 as well. Mechanical exfoliation Mechanically exfoliating graphite using scotch tape to produce graphene films of graphite Oxidizing graphite to form graphite oxide or starting with expandable graphite or graphite

  17. Simulation of the Manufacturing of Non-Crimp Fabric-Reinforced Composite Wind Turbine Blades to Predict the Formation of Wave Defects

    SciTech Connect (OSTI)

    Fetfatsidis, K. A.; Sherwood, J. A. [Department of Mechanical Engineering, University of Massachusetts, Lowell One University Ave., Lowell, MA 01854 (United States)

    2011-05-04T23:59:59.000Z

    NCFs (Non-Crimp Fabrics) are commonly used in the design of wind turbine blades and other complex systems due to their ability to conform to complex shapes without the wrinkling that is typically experienced with woven fabrics or prepreg tapes. In the current research, a form of vacuum assisted resin transfer molding known as SCRIMP registered is used to manufacture wind turbine blades. Often, during the compacting of the fabric layers by the vacuum pressure, several plies may bunch together out-of-plane and form wave defects. When the resin is infused, the areas beneath the waves become resin rich and can compromise the structural integrity of the blade. A reliable simulation tool is valuable to help predict where waves and other defects may appear as a result of the manufacturing process. Forming simulations often focus on the in-plane shearing and tensile behavior of fabrics and do not necessarily consider the bending stiffness of the fabrics, which is important to predict the formation of wrinkles and/or waves. This study incorporates experimentally determined in-plane shearing, tensile, and bending stiffness information of NCFs into a finite element model (ABAQUS/Explicit) of a 9-meter wind turbine blade to investigate the mechanical behaviors that can lead to the formation of waves as a result of the manufacturing process.

  18. Determining thermal diffusivity and defect attributes in ceramic matrix composites by infrared imaging.

    SciTech Connect (OSTI)

    Ahuja, S.; Ellingson, W. A.; Koehl, E. R.; Stuckey, J.

    1997-12-05T23:59:59.000Z

    Ceramic matrix composites are being developed for numerous high temperature applications, including rotors and combustors for advanced turbine engines, heat exchanger and hot-gas filters for coal gasification plants. Among the materials of interest are silicon-carbide-fiber-reinforced-silicon-carbide (SiC{sub (f)}/SiC), silicon-carbide-fiber-reinforced-silicon-nitride (SiC{sub (f)}/Si{sub 3}N{sub 4}), aluminum-oxide-reinforced-alumina (Al{sub 2}O{sub 3(f)}/Al{sub 2}O{sub 3}), etc. In the manufacturing of these ceramic composites, the conditions of the fiber/matrix interface are critical to the mechanical and thermal behavior of the component. Defects such as delaminations and non-uniform porosity can directly effect the performance. A nondestructive evaluation (NDE) method, developed at Argonne National Laboratory has proved beneficial in analyzing as-processed conditions and defect detection created during manufacturing. This NDE method uses infrared thermal imaging for fill-field quantitative measurement of the distribution of thermal diffusivity in large components. Intensity transform algorithms have been used for contrast enhancement of the output image. Nonuniformity correction and automatic gain control are used to dynamically optimize video contrast and brightness, providing additional resolution in the acquired images. Digital filtering, interpolation, and least-squares-estimation techniques have been incorporated for noise reduction and data acquisition. The Argonne NDE system has been utilized to determine thermal shock damage, density variations, and variations in fiber coating in a full array of test specimens.

  19. Exploring the eddy current excitation invariance to infer about defect characteristics

    SciTech Connect (OSTI)

    Ribeiro, A. Lopes; Ramos, H. G. [I and M Group, Instituto de Telecomunicacoes, Lisboa, Portugal Instituto Superior Tecnico, DEEC, Lisboa (Portugal)

    2011-06-23T23:59:59.000Z

    This paper explores the excitation probe excitation field invariance when the eddy current method is applied to detect, localize and characterize material defects in conductive nonmagnetic media. The cases relative to rotational symmetry in circular solenoidal probes and translation symmetry in constant field probes are presented. The experimental data shows that this theoretical treatment is useful to preview the behavior of these probes.

  20. Evolution of Topological Defects During Inflation

    E-Print Network [OSTI]

    R. Basu; A. Vilenkin

    1994-02-22T23:59:59.000Z

    Topological defects can be formed during inflation by phase transitions as well as by quantum nucleation. We study the effect of the expansion of the Universe on the internal structure of the defects. We look for stationary solutions to the field equations, i.e. solutions that depend only on the proper distance from the defect core. In the case of very thin defects, whose core dimensions are much smaller than the de Sitter horizon, we find that the solutions are well approximated by the flat space solutions. However, as the flat space thickness parameter $\\delta_0$ increases we notice a deviation from this, an effect that becomes dramatic as $\\delta_0$ approaches $(H)^{-1}/{\\sqrt 2}$. Beyond this critical value we find no stationary solutions to the field equations. We conclude that only defects that have flat space thicknesses less than the critical value survive, while thicker defects are smeared out by the expansion.

  1. Space-time defects and teleparallelism

    E-Print Network [OSTI]

    J. W. Maluf; A. Goya

    2001-10-24T23:59:59.000Z

    We consider the class of space-time defects investigated by Puntigam and Soleng. These defects describe space-time dislocations and disclinations (cosmic strings), and are in close correspondence to the actual defects that arise in crystals and metals. It is known that in such materials dislocations and disclinations require a small and large amount of energy, respectively, to be created. The present analysis is carried out in the context of the teleparallel equivalent of general relativity (TEGR). We evaluate the gravitational energy of these space-time defects in the framework of the TEGR and find that there is an analogy between defects in space-time and in continuum material systems: the total gravitational energy of space-time dislocations and disclinations (considered as idealized defects) is zero and infinit, respectively.

  2. Predicting the equilibria of point defects in zirconium oxide : a route to understand the corrosion and hydrogen pickup of zirconium alloys

    E-Print Network [OSTI]

    Youssef, Mostafa Youssef Mahmoud

    2014-01-01T23:59:59.000Z

    The performance of zirconium alloys in nuclear reactors is compromised by corrosion and hydrogen pickup. The thermodynamics and kinetics of these two processes are governed by the behavior of point defects in the ZrO? layer ...

  3. Failure Pressure Estimates of Steam Generator Tubes Containing Wear-type Defects

    SciTech Connect (OSTI)

    Yoon-Suk Chang; Jong-Min Kim; Nam-Su Huh; Young-Jin Kim [School of Mechanical Engineering, Sungkyunkwan University (Korea, Republic of); Seong Sik Hwang; Joung-Soo Kim [Korea Atomic Energy Research Institute (Korea, Republic of)

    2006-07-01T23:59:59.000Z

    It is commonly requested that steam generator tubes with defects exceeding 40% of wall thickness in depth should be plugged to sustain all postulated loads with appropriate margin. The critical defect dimensions have been determined based on the concept of plastic instability. This criterion, however, is known to be too conservative for some locations and types of defects. In this context, the accurate failure estimation for steam generator tubes with a defect draws increasing attention. Although several guidelines have been developed and are used for assessing the integrity of defected tubes, most of these guidelines are related to stress corrosion cracking or wall-thinning phenomena. As some of steam generator tubes are also failed due to fretting and so on, alternative failure estimation schemes for relevant defects are required. In this paper, three-dimensional finite element (FE) analyses are carried out under internal pressure condition to simulate the failure behavior of steam generator tubes with different defect configurations; elliptical wastage type, wear scar type and rectangular wastage type defects. Maximum pressures based on material strengths are obtained from more than a hundred FE results to predict the failure of the steam generator tube. After investigating the effect of key parameters such as wastage depth, wastage length and wrap angle, simplified failure estimation equations are proposed in relation to the equivalent stress at the deepest point in wastage region. Comparison of failure pressures predicted according to the proposed estimation scheme with some corresponding burst test data shows good agreement, which provides a confidence in the use of the proposed equations to assess the integrity of steam generator tubes with wear-type defects. (authors)

  4. CASTING DEFECT MODELING IN AN INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING APPROACH

    SciTech Connect (OSTI)

    Sabau, Adrian S [ORNL

    2015-01-01T23:59:59.000Z

    To accelerate the introduction of new cast alloys, the simultaneous modeling and simulation of multiphysical phenomena needs to be considered in the design and optimization of mechanical properties of cast components. The required models related to casting defects, such as microporosity and hot tears, are reviewed. Three aluminum alloys are considered A356, 356 and 319. The data on calculated solidification shrinkage is presented and its effects on microporosity levels discussed. Examples are given for predicting microporosity defects and microstructure distribution for a plate casting. Models to predict fatigue life and yield stress are briefly highlighted here for the sake of completion and to illustrate how the length scales of the microstructure features as well as porosity defects are taken into account for modeling the mechanical properties. Thus, the data on casting defects, including microstructure features, is crucial for evaluating the final performance-related properties of the component. ACKNOWLEDGEMENTS This work was performed under a Cooperative Research and Development Agreement (CRADA) with the Nemak Inc., and Chrysler Co. for the project "High Performance Cast Aluminum Alloys for Next Generation Passenger Vehicle Engines. The author would also like to thank Amit Shyam for reviewing the paper and Andres Rodriguez of Nemak Inc. Research sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, as part of the Propulsion Materials Program under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Part of this research was conducted through the Oak Ridge National Laboratory's High Temperature Materials Laboratory User Program, which is sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program.

  5. Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond

    E-Print Network [OSTI]

    I. Popa; T. Gaebel; M. Domhan; C. Wittmann; F. Jelezko; J. Wrachtrup

    2004-09-12T23:59:59.000Z

    The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.

  6. Physical process Mechanical mechanisms

    E-Print Network [OSTI]

    Berlin,Technische Universität

    1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F = B·i·l · Fluid dynamic/Hydraulic mechanisms q, p, ij · Thermal/Optical #12;2 Source unit

  7. High-Temperature Mechanical Behavior and Hot Rolling S.F. HARNISH, H.A. PADILLA, B.E. GORE, J.A. DANTZIG, A.J. BEAUDOIN,

    E-Print Network [OSTI]

    Dantzig, Jonathan A.

    and processing performance of 705X aluminum alloys is exam- ined, employing a combination of mechanical testing aluminum has been one of the most widely successful and broadly applicable materials devel- oped of these alloys include packaging, automotive, and aerospace. The Al-Zn- Mg-Cu 7000 series alloys have seen

  8. Evaluation of the thermal-hydraulic response and fuel rod thermal and mechanical deformation behavior during the power burst facility test LOC-3. [PWR

    SciTech Connect (OSTI)

    Yackle, T.R.; MacDonald, P.E.; Broughton, J.M.

    1980-01-01T23:59:59.000Z

    An evaluation of the results from the LOC-3 nuclear blowdown test conducted in the Power Burst Facility is presented. The test objective was to examine fuel and cladding behavior during a postulated cold leg break accident in a pressurized water reactor (PWR). Separate effects of rod internal pressure and the degree of irradiation were investigated in the four-rod test. Extensive cladding deformation (ballooning) and failure occurred during blowdown. The deformation of the low and high pressure rods was similar; however, the previously irradiated test rod deformed to a greater extent than a similar fresh rod exposed to identical system conditions.

  9. Defect Analysis of Vehicle Compressed Natural Gas

    E-Print Network [OSTI]

    Defect Analysis of Vehicle Compressed Natural Gas Composite Cylinder A China Paper on Type 4;Industrial Computed Tomography (CT) Examination of Composite Gas Cylinder #12;CT of 01-01 Layer at 4.8MPa during the gas compressing and releasing processes are the direct causes for liner defect - Since

  10. DefectDomain Wall Interactions in Trigonal

    E-Print Network [OSTI]

    Gopalan, Venkatraman

    Defect­Domain Wall Interactions in Trigonal Ferroelectrics Venkatraman Gopalan,1 Volkmar Dierolf,2 walls in the trigonal ferroelectrics lithium niobate and lithium tantalate. It is shown that extrinsic questions re- garding intrinsic widths, defect­domain wall interactions, and static versus dynamic wall

  11. Predicting software defects in varying development lifecycles

    E-Print Network [OSTI]

    Bae, Doo-Hwan

    Predicting software defects in varying development lifecycles using Bayesian nets Information and Software Technology (2007) Norman Fenton, Martin Neil, William March, Peter HyeonJeong Kim KAIST SE LAB #12;Contents Introduction Overall approach Analyzing the lifecycle Modeling the defect prediction

  12. Leak before break behaviour of austenitic and ferritic pipes containing circumferential defects

    SciTech Connect (OSTI)

    Stadtmueller, W.; Sturm, D.

    1997-04-01T23:59:59.000Z

    Several research projects carried out at MPA Stuttgart to investigate the Leak-before-Break (LBB) behavior of safety relevant pressure bearing components are summarized. Results presented relate to pipes containing circumferential defects subjected to internal pressure and external bending loading. An overview of the experimentally determined results for ferritic components is presented. For components containing postulated or actual defects, the dependence of the critical loading limit on the defect size is shown in the form of LBB curves. These are determined experimentally and/or by calculation for through-wall slits, and represent the boundary curve between leakage and massive fracture. For surface defects and a given bending moment and internal pressure, no fracture will occur if the length at leakage remains smaller than the critical defect length given by the LBB curve for through-wall defects. The predictive capability of engineering calculational methods are presented by way of example. The investigation programs currently underway, testing techniques, and initial results are outlined.

  13. Quantitative Modeling of Polymer Scratch Behavior 

    E-Print Network [OSTI]

    Hossain, Mohammad Motaher

    2013-12-02T23:59:59.000Z

    dependent mechanical behavior and pressure dependent frictional behavior in the FEM model, good agreement has been found between FEM simulation and experimental observations. The results suggest that, by including proper constitutive relationship...

  14. Structures And Magnetization Of Defect-Associated Sites In Silicon

    SciTech Connect (OSTI)

    Chow, L.; Gonzalez-Pons, J. C.; Barco, E. del [Department of Physics, University of Central Florida, Orlando, FL 32816-2385 (United States); Vanfleet, R. [Department of Physics, Brigham Young University, Provo, UT 84602 (United States); Misiuk, A. [Institute of Electron Technology (ITE), al. Lotnikow 32/46, Warsaw 02-668 Poland (Poland); Barcz, A. [Institute of Electron Technology (ITE), al. Lotnikow 32/46, Warsaw 02-668 Poland (Poland); Polish Academy of Science, Institute of Physics, al Lotnikow 32/46, Warsaw 02-668 Poland (Poland); Choi, E. S. [NHMFL, Florida State University, Tallahassee, FL 32310-3706 (United States); Chai, G. [Apollo Technologies, Inc. 205 Waymont Court, Suite 111, Lake Mary, FL 32746 (United States)

    2008-04-24T23:59:59.000Z

    To better understand the mechanism of the reported 'quasi-ferromagnetism' observed in Si ions self-implanted or irradiated silicon, we carry out high resolution transmission electron microscopy (HRTEM), magnetization measurements using superconducting quantum interference device (SQUID) magnetometer, and ferromagnetic resonance (FMR) measurements of the magnetic interaction of the defect-associated sites in silicon damaged by silicon self-implantation or energetic particle beams. The SQUID measurements showed that the silicon self-implanted sample has paramagnetic ordering. FMR measurements indicated the He{sup ++} irradiated sample has a ferromagnetic interaction and yields a Lande g-factor of 2.35.

  15. Exploration of Quench Initiation Due to Intentional Geometrical Defects in a High Magnetic Field Region of an SRF Cavity

    SciTech Connect (OSTI)

    J. Dai, K. Zhao, G.V. Eremeev, R.L. Geng, A.D. Palczewski; Dai, J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Palczewski, A. D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Eremeev, G. V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Geng, R. L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhao, K. [Institute of Heavy Ion Physics, Peking University, Beijing (China)

    2011-07-01T23:59:59.000Z

    A computer program which was used to simulate and analyze the thermal behaviors of SRF cavities has been developed at Jefferson Lab using C++ code. This code was also used to verify the quench initiation due to geometrical defects in high magnetic field region of SRF cavities. We built a CEBAF single cell cavity with 4 artificial defects near equator, and this cavity has been tested with T-mapping. The preheating behavior and quench initiation analysis of this cavity will be presented here using the computer program.

  16. Coulomb screening in graphene with topological defects

    E-Print Network [OSTI]

    Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen

    2015-02-20T23:59:59.000Z

    We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.

  17. Modeling defective part level due to static and dynamic defects based upon site observation and excitation balance

    E-Print Network [OSTI]

    Dworak, Jennifer Lynn

    2004-09-30T23:59:59.000Z

    defect detection. We deterministically maximize the observations of the leastobserved sites while randomly exciting the defects that may be present. The resulting decrease in defective part level is estimated using the MPGD model. This dissertation...

  18. Defect classes - an overdue paradigm for CMOS IC testing

    SciTech Connect (OSTI)

    Hawkins, C.F. [Univ. of New Mexico, Albuquerque, NM (United States); Soden, J.M.; Righter, A.W. [Sandia National Labs., Albuquerque, NM (United States); Ferguson, F.J. [Univ. of California, Santa Cruz, CA (United States)

    1994-09-01T23:59:59.000Z

    The IC test industry has struggled for more than 30 years to establish a test approach that would guarantee a low defect level to the customer. We propose a comprehensive strategy for testing CMOS ICs that uses defect classes based on measured defect electrical properties. Defect classes differ from traditional fault models. Our defect class approach requires that the test strategy match the defect electrical properties, while fault models require that IC defects match the fault definition. We use data from Sandia Labs failure analysis and test facilities and from public literature. We describe test pattern requirements for each defect class and propose a test paradigm.

  19. Defect Distribution and Dissolution Morphologies on Low-Index...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defect Distribution and Dissolution Morphologies on Low-Index Surfaces of alpha-Quartz . Defect Distribution and Dissolution Morphologies on Low-Index Surfaces of alpha-Quartz ....

  20. Energetics of Defects on Graphene through Fluorination. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defects on Graphene through Fluorination. Energetics of Defects on Graphene through Fluorination. Abstract: In the present study, we used FGS5 as the substrate and implemented...

  1. Exploring the interaction between lithium ion and defective graphene...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies. Exploring the interaction between lithium ion and defective...

  2. Modification of Defect Structures in Graphene by Electron Irradiation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Modification of Defect Structures in Graphene by Electron Irradiation: Ab Initio Molecular Dynamics Simulations. Modification of Defect Structures in Graphene by Electron...

  3. Role of Point Defects on the Reactivity of Reconstructed Anatase...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Point Defects on the Reactivity of Reconstructed Anatase Titanium Dioxide (001) Surface. Role of Point Defects on the Reactivity of Reconstructed Anatase Titanium Dioxide (001)...

  4. 3.225 Electronic and Mechanical Properties of Materials, Summer 2002

    E-Print Network [OSTI]

    Gibson, Lorna J.

    2002-01-01T23:59:59.000Z

    Electrical, optical, magnetic, and mechanical properties of metals, semiconductors, ceramics and polymers. Discussion of roles of bonding, structure (crystalline, defect, energy band and microstructure) and composition in ...

  5. Ventilation Behavior and Household Characteristics in New California Houses

    E-Print Network [OSTI]

    Price, Phillip N.; Sherman, Max H.

    2006-01-01T23:59:59.000Z

    pollutant sources get more ventilation. • Except householdshealth issues motivate ventilation behavior. • Security andQuality, IAQ, mechanical ventilation systems, ventilation

  6. Atomic-scale electron-beam sculpting of defect-free graphene nanostructures

    E-Print Network [OSTI]

    Dekker, Cees

    Atomic-scale electron-beam sculpting of defect-free graphene nanostructures Bo Song, Grégory F.w.zandbergen@tudelft.nl ABSTRACT. In order to harvest the many promising properties of graphene in (electronic) applications a temperature-dependent self-repair mechanism allowing damage-free atomic-scale sculpting of graphene using

  7. PARTIAL DISCHARGE TESTING OF DEFECTIVE THREE-PHASE PILC CABLE UNDER RATED CONDITIONS

    E-Print Network [OSTI]

    Southampton, University of

    PARTIAL DISCHARGE TESTING OF DEFECTIVE THREE-PHASE PILC CABLE UNDER RATED CONDITIONS J. A. Hunter 1 lifespan. An increase in the failure rates of paper insulated lead covered (PILC) cables that make up is to document the effects of mechanical stress on the generation of partial discharge (PD) for cables of PILC

  8. Effects of boron-nitride substrates on Stone-Wales defect formation in graphene: An ab initio molecular dynamics study

    SciTech Connect (OSTI)

    Jin, K.; Xiao, H. Y. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Zhang, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Weber, W. J., E-mail: wjweber@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-05-19T23:59:59.000Z

    Ab initio molecular dynamics simulations are performed to investigate the effects of a boron nitride (BN) substrate on Stone-Wales (SW) defect formation and recovery in graphene. It is found that SW defects can be created by an off-plane recoil atom that interacts with the BN substrate. A mechanism with complete bond breakage for formation of SW defects in suspended graphene is also revealed for recoils at large displacement angles. In addition, further irradiation can result in recovery of the SW defects through a bond rotation mechanism in both graphene and graphene/BN, and the substrate has little effect on the recovery process. This study indicates that the BN substrate enhances the irradiation resistance of graphene.

  9. Di-interstitial defect in silicon revisited

    SciTech Connect (OSTI)

    Londos, C. A.; Antonaras, G. [Solid State Section, Physics Department, University of Athens, Panepistimiopolis, Zografos, 157 84 Athens (Greece)] [Solid State Section, Physics Department, University of Athens, Panepistimiopolis, Zografos, 157 84 Athens (Greece); Chroneos, A. [Engineering and Innovation, The Open University, Milton Keynes MK7 6AA (United Kingdom) [Engineering and Innovation, The Open University, Milton Keynes MK7 6AA (United Kingdom); Department of Materials, Imperial College London, London SW7 2BP (United Kingdom)

    2013-11-21T23:59:59.000Z

    Infrared spectroscopy was used to study the defect spectrum of Cz-Si samples following fast neutron irradiation. We mainly focus on the band at 533 cm{sup ?1}, which disappears from the spectra at ?170 °C, exhibiting similar thermal stability with the Si-P6 electron paramagnetic resonance (EPR) spectrum previously correlated with the di-interstitial defect. The suggested structural model of this defect comprises of two self-interstitial atoms located symmetrically around a lattice site Si atom. The band anneals out following a first-order kinetics with an activation energy of 0.88 ± 0.3 eV. This value does not deviate considerably from previously quoted experimental and theoretical values for the di-interstitial defect. The present results indicate that the 533 cm{sup ?1} IR band originates from the same structure as that of the Si-P6 EPR spectrum.

  10. Generalized quantum defect methods in quantum chemistry

    E-Print Network [OSTI]

    Altunata, Serhan

    2006-01-01T23:59:59.000Z

    The reaction matrix of multichannel quantum defect theory, K, gives a complete picture of the electronic structure and the electron - nuclear dynamics for a molecule. The reaction matrix can be used to examine both bound ...

  11. Sandia National Laboratories: Defect-Carrier Interactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with SSLS scientist Andy Armstrong using deep level optical spectroscopy to investigate defects in the m-plane GaN. Jim is a professor ... Last Updated: September 6, 2013...

  12. Two-dimensional defects in amorphous materials

    E-Print Network [OSTI]

    Michael Moshe; Eran Sharon; Ido Levin; Hillel Aharoni; Raz Kupferman

    2014-09-09T23:59:59.000Z

    We present a new definition of defects which is based on a Riemannian formulation of incompatible elasticity. Defects are viewed as local deviations of the material's reference metric field, $\\bar{\\mathfrak{g}}$, from a Euclidian metric. This definition allows the description of defects in amorphous materials and the formulation of the elastic problem, using a single field, $\\bar{\\mathfrak{g}}$. We provide a multipole expansion of reference metrics that represent a large family of two-dimensional (2D) localized defects. The case of a dipole, which corresponds to an edge dislocation is studied analytically, experimentally and numerically. The quadrupole term, which is studied analytically, as well as higher multipoles of curvature carry local deformations. These multipoles are good candidates for fundamental strain carrying entities in plasticity theories of amorphous materials and for a continuous modeling of recently developed meta-materials.

  13. Defect analysis using resonant ultrasound spectroscopy 

    E-Print Network [OSTI]

    Flynn, Kevin Joseph

    2009-05-15T23:59:59.000Z

    This thesis demonstrates the practicability of using Resonant Ultrasound Spectroscopy (RUS) in combination with Finite Element Analysis (FEA) to determine the size and location of a defect in a material of known geometry ...

  14. From Quantum Mechanics to Thermodynamics?

    E-Print Network [OSTI]

    Steinhoff, Heinz-Jürgen

    From Quantum Mechanics to Thermodynamics? Dresden, 22.11.2004 Jochen Gemmer Universit¨at Osnabr to thermodynamical behavior · Quantum approach to thermodynamical behavior · The route to equilibrium · Summary of thermodynamical behavior entirely on the basis of Hamilton models and Schr¨odinger-type quantum dynamics. · define

  15. INNOVATIVE EDDY CURRENT PROBE FOR MICRO DEFECTS

    SciTech Connect (OSTI)

    Santos, Telmo G.; Vilaca, Pedro; Quintino, Luisa [IDMEC, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Santos, Jorge dos [GKSS, Max-Planck-Street 1, D-21502 Geesthacht (Germany); Rosado, Luis [IST, UTL, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)

    2010-02-22T23:59:59.000Z

    This paper reports the development of an innovative eddy current (EC) probe, and its application to micro-defects on the root of the Friction Stir Welding (FSW). The new EC probe presents innovative concept issues, allowing 3D induced current in the material, and a lift-off independence. Validation experiments were performed on aluminium alloys processed by FSW. The results clearly show that the new EC probe is able to detect and sizing surface defects about 60 microns depth.

  16. Last Passage Percolation with a Defect Line and the Solution of the Slow Bond Problem

    E-Print Network [OSTI]

    Riddhipratim Basu; Vladas Sidoravicius; Allan Sly

    2014-08-18T23:59:59.000Z

    We address the question of how a localized microscopic defect, especially if it is small with respect to certain dynamic parameters, affects the macroscopic behavior of a system. In particular we consider two classical exactly solvable models: Ulam's problem of the maximal increasing sequence and the totally asymmetric simple exclusion process. For the first model, using its representation as a Poissonian version of directed last passage percolation on $\\mathbb R^2$, we introduce the defect by placing a positive density of extra points along the diagonal line. For the latter, the defect is produced by decreasing the jump rate of each particle when it crosses the origin. The powerful algebraic tools for studying these processes break down in the perturbed versions of the models. Taking a more geometric approach we show that in both cases the presence of an arbitrarily small defect affects the macroscopic behavior of the system: in Ulam's problem the time constant increases, and for the exclusion process the flux of particles decreases. This, in particular, settles the longstanding Slow Bond Problem.

  17. Manufacturing Defects Common to Composite Wind Turbine Blades: Effects of Defects

    E-Print Network [OSTI]

    uni-directional wind turbine fiber-reinforced composite material with an epoxy resin were utilized of wind turbine blades have essentially dictated the use of low cost fiberglass composite materials. Even1 Manufacturing Defects Common to Composite Wind Turbine Blades: Effects of Defects Jared W. Nelson

  18. A topological point defect regulates the evolution of extended defects in irradiated silicon

    E-Print Network [OSTI]

    Wilkins, John

    functional theory calculations establish formation energies, activation barriers, and electronic structures structure. Compared to the experimental gap of 1.16 eV for bulk Si,16 the calculated HSE gap, 1.15 eV, shows interstitial defects in irradiated silicon. Molecular dynamics simulations reveal the role of the bond defect

  19. High-Power Detectors Newport Corporation warrants this product to be free from defects In material and

    E-Print Network [OSTI]

    Kleinfeld, David

    High-Power Detectors #12;Warranty Newport Corporation warrants this product to be free from defects.3 Unpacking and Inspection 2 Section 2 - Detector Operation 2.1 Introduction 3 2.2 Power Signal Behavior 3 2 Reflections 7 2.7 Spectral Response 8 2.8 Care for High-Power Detectors 9 2.9 Detector Recalibration 9 Section

  20. Carbon Clusters as Possible Defects in the SiC-SiO2 Interface

    SciTech Connect (OSTI)

    Dang, Hongli [ORNL; Ramkumar, Gudipati [unknown; Yang, Liu [unknown; Li, Ying [ORNL; Peterson, Heather [unknown; Chisholm, Matthew F [ORNL; Biggerstaff, Trinity Leigh [ORNL; Duscher, Gerd [University of Tennessee, Knoxville (UTK); Wang, Sanwu [ORNL

    2009-01-01T23:59:59.000Z

    High state densities in the band gap of the SiC-SiO2 interface significantly reduce the channel mobilities in SiC-based high-temperature/high-power microelectronics. Investigations of the nature of the interface defects are thus of great importance. While several possible defects including very small carbon clusters with up to four carbon atoms have been identified by first-principles theory, larger carbon clusters as possible defects have attracted less attention. Here, we report first-principles quantum-mechanical calculations for two larger carbon clusters, the C10 ring and the C20 fullerence, in the SiC-SiO2 interface. We find that both carbon clusters introduce significant states in the band gap. The states extend over the entire band gap with higher densities in the upper half of the gap, thus accounting for some of the interface trap densities observed experimentally

  1. The effects of fastener hole defects

    E-Print Network [OSTI]

    Andrews, Scot D.

    1991-01-01T23:59:59.000Z

    ) August 1991 ABSTRACT The Effects of Fastener Hole Defects. (August 1991) Scot D. Andrews, B. S. , Texas A8rM University Chair of Advisory Committee: Dr. Orden O. Ochoa The influence of drilling-induced defects, such as delamination, on the fatigue... ambient and elevated temperature wet conditions. Specimens were tested in a bearing tension frame to static failure in order to measure the failure load and to calculate pin bearing stress. From static test results, a fatigue load was selected as 66...

  2. Bistable defect structures in blue phase devices

    E-Print Network [OSTI]

    A. Tiribocchi; G. Gonnella; D. Marenduzzo; E. Orlandini; F. Salvadore

    2011-10-28T23:59:59.000Z

    Blue phases (BPs) are liquid crystals made up by networks of defects, or disclination lines. While existing phase diagrams show a striking variety of competing metastable topologies for these networks, very little is known as to how to kinetically reach a target structure, or how to switch from one to the other, which is of paramount importance for devices. We theoretically identify two confined blue phase I systems in which by applying an appropriate series of electric field it is possible to select one of two bistable defect patterns. Our results may be used to realise new generation and fast switching energy-saving bistable devices in ultrathin surface treated BPI wafers.

  3. GaN: Defect and Device Issues

    SciTech Connect (OSTI)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09T23:59:59.000Z

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  4. Tuning Interfacial Thermal Conductance of Graphene Embedded in Soft Materials by Vacancy Defects

    SciTech Connect (OSTI)

    Liu, Ying [Clemson University; Hu, Chongze [Clemson University; Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Qiao, Rui [Engineering Science and Mechanics Department, Virginia Tech, Blacksburg, VA, USA

    2015-01-01T23:59:59.000Z

    Nanocomposites based on graphene dispersed in matrices of soft materials are promising thermal management materials. Their effective thermal conductivity depends on both the thermal conductivity of graphene and the conductance of the thermal transport across graphene-matrix interfaces. Here we report on molecular dynamics simulations of the thermal transport across the interfaces between defected graphene and soft materials in two different modes: in the across mode, heat enters graphene from one side of its basal plane and leaves through the other side; in the non-across mode, heat enters or leaves a graphene simultaneously from both sides of its basal plane. We show that, as the density of vacancy defects in graphene increases from 0 to 8%, the conductance of the interfacial thermal transport in the across mode increases from 160.4 16 to 207.8 11 MW/m2K, while that in the non-across mode increases from 7.2 0.1 to 17.8 0.6 MW/m2K. The molecular mechanisms for these variations of thermal conductance are clarified by using the phonon density of states and structural characteristics of defected graphenes. On the basis of these results and effective medium theory, we show that it is possible to enhance the effective thermal conductivity of thermal nanocomposites by tuning the density of vacancy defects in graphene despite the fact that graphene s thermal conductivity always decreases as vacancy defects are introduced.

  5. Mechanics of Notched Izod impact testing of polycarbonate

    E-Print Network [OSTI]

    Silberstein, Meredith N

    2005-01-01T23:59:59.000Z

    Polycarbonate is widely used as a transparent protective material because of its low density and excellent mechanical properties. However, when defects such as cracks or notches are introduced, it is subject to catastrophic ...

  6. Gauge turbulence, topological defect dynamics, and condensation in Higgs models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gasenzer, Thomas [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany); McLerran, Larry [Brookhaven National Laboratory, Physics Department, RIKEN BNL Research Center Upton NY (United States); China Central Normal University, Physics Department, Wuhan (China); Pawlowski, Jan M [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany); Sexty, Denes [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany)

    2014-10-01T23:59:59.000Z

    The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.

  7. Gauge turbulence, topological defect dynamics, and condensation in Higgs models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gasenzer, Thomas; McLerran, Larry; Pawlowski, Jan M.; Sexty, Dénes

    2014-10-01T23:59:59.000Z

    The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixedmore »point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.« less

  8. Linear elastic fracture mechanics in anisotropic solids : application to fluid-driven crack propagation

    E-Print Network [OSTI]

    Laubie, Hadrien Hyacinthe

    2013-01-01T23:59:59.000Z

    Fracture mechanics is a field of continuum mechanics with the objective to predict how cracks initiate and propagate in solids. It has a wide domain of application. While aerospace engineers want to make sure a defect in ...

  9. A MULTIDIMENSIONAL AND MULTIPHYSICS APPROACH TO NUCLEAR FUEL BEHAVIOR SIMULATION

    SciTech Connect (OSTI)

    R. L. Williamson; J. D. Hales; S. R. Novascone; M. R. Tonks; D. R. Gaston; C. J. Permann; D. Andrs; R. C. Martineau

    2012-04-01T23:59:59.000Z

    Important aspects of fuel rod behavior, for example pellet-clad mechanical interaction (PCMI), fuel fracture, oxide formation, non-axisymmetric cooling, and response to fuel manufacturing defects, are inherently multidimensional in addition to being complicated multiphysics problems. Many current modeling tools are strictly 2D axisymmetric or even 1.5D. This paper outlines the capabilities of a new fuel modeling tool able to analyze either 2D axisymmetric or fully 3D models. These capabilities include temperature-dependent thermal conductivity of fuel; swelling and densification; fuel creep; pellet fracture; fission gas release; cladding creep; irradiation growth; and gap mechanics (contact and gap heat transfer). The need for multiphysics, multidimensional modeling is then demonstrated through a discussion of results for a set of example problems. The first, a 10-pellet rodlet, demonstrates the viability of the solution method employed. This example highlights the effect of our smeared cracking model and also shows the multidimensional nature of discrete fuel pellet modeling. The second example relies on our the multidimensional, multiphysics approach to analyze a missing pellet surface problem. As a final example, we show a lower-length-scale simulation coupled to a continuum-scale simulation.

  10. PAH Sorption Mechanism and Partitioning Behavior in

    E-Print Network [OSTI]

    Zare, Richard N.

    . Introduction Prior to the widespread distribution of natural gas, manu- factured gas from coke, coal, and oil. In the eastern United States, where coal was plentiful, gas was derived from coal or coke. Along the West Coast, because of the availability of oil and the expense in transporting coal or coke to this region, gas

  11. Coulomb screening in graphene with topological defects

    E-Print Network [OSTI]

    Chakraborty, Baishali; Sen, Siddhartha

    2015-01-01T23:59:59.000Z

    We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb imp...

  12. Brake Defect Causation and Abatement Study (BDCAS)

    E-Print Network [OSTI]

    on various lining materials for comparison study #12;Center for Transportation Analysis 2360 CherahalaBrake Defect Causation and Abatement Study (BDCAS) Oak Ridge National Laboratory managed by UT Based Brake Testers (PBBTs) part of the out-of- service criterion for commercial motor vehicles in 2007

  13. Defect- and Strain-enhanced Cavity Formation and Au Precipitation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defect- and Strain-enhanced Cavity Formation and Au Precipitation at nano-crystalline ZrO2SiO2Si Interfaces . Defect- and Strain-enhanced Cavity Formation and Au Precipitation at...

  14. Estimating the expected latency to failure due to manufacturing defects 

    E-Print Network [OSTI]

    Dorsey, David Michael

    2004-09-30T23:59:59.000Z

    Manufacturers of digital circuits test their products to find defective parts so they are not sold to customers. Despite extensive testing, some of their products that are defective pass the testing process. To combat ...

  15. Healing of defects in a two-dimensional granular crystal

    E-Print Network [OSTI]

    Rice, Marie C

    2014-01-01T23:59:59.000Z

    Using a macroscopic analog for a two dimensional hexagonal crystal, we perform an experimental investigation of the self-healing properties of circular grain defects with an emphasis on defect orientation. A circular grain ...

  16. Direct imaging of crystal structure and defects in metastable Ge{sub 2}Sb{sub 2}Te{sub 5} by quantitative aberration-corrected scanning transmission electron microscopy

    SciTech Connect (OSTI)

    Ross, Ulrich; Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Thelander, Erik; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318 Leipzig (Germany)

    2014-03-24T23:59:59.000Z

    Knowledge about the atomic structure and vacancy distribution in phase change materials is of foremost importance in order to understand the underlying mechanism of fast reversible phase transformation. In this Letter, by combining state-of-the-art aberration-corrected scanning transmission electron microscopy with image simulations, we are able to map the local atomic structure and composition of a textured metastable Ge{sub 2}Sb{sub 2}Te{sub 5} thin film deposited by pulsed laser deposition with excellent spatial resolution. The atomic-resolution scanning transmission electron microscopy investigations display the heterogeneous defect structure of the Ge{sub 2}Sb{sub 2}Te{sub 5} phase. The obtained results are discussed. Highly oriented Ge{sub 2}Sb{sub 2}Te{sub 5} thin films appear to be a promising approach for further atomic-resolution investigations of the phase change behavior of this material class.

  17. Automated Diagnosis and Classification of Steam Generator Tube Defects

    SciTech Connect (OSTI)

    Dr. Gabe V. Garcia

    2004-10-01T23:59:59.000Z

    A major cause of failure in nuclear steam generators is tube degradation. Tube defects are divided into seven categories, one of which is intergranular attack/stress corrosion cracking (IGA/SCC). Defects of this type usually begin on the outer surface of the tubes and propagate both inward and laterally. In many cases these defects occur at or near the tube support plates. Several different methods exist for the nondestructive evaluation of nuclear steam generator tubes for defect characterization.

  18. Collective phenomena in defect crystals Reimer Kuhn1,

    E-Print Network [OSTI]

    Kühn, Reimer

    by quantum effects. Both thermal and dynamical properties are considered. The influence of interactions Talence cedex, France Received 25 April 2000 We investigate the effects of interactions between substitutional defects on the properties of defect crystals at low temperatures, where defect motion is governed

  19. Critical Area Computation for Missing Material Defects in VLSI Circuits

    E-Print Network [OSTI]

    Papadopoulou, Evanthia

    Critical Area Computation for Missing Material Defects in VLSI Circuits Evanthia Papadopoulou IBM the problem of computing critical area for miss- ing material defects in a circuit layout. The extraction of critical area is the main computational problem in VLSI yield prediction. Missing material defects cause

  20. Metastable light induced defects in pentacene

    SciTech Connect (OSTI)

    Liguori, R.; Aprano, S.; Rubino, A. [Department of Industrial Engineering (DIIn), University of Salerno, via Giovanni Paolo II, 132, 84084 Fisciano (Italy)

    2014-02-21T23:59:59.000Z

    In this study we analyzed one of the environmental factors that could affect organic materials. Pentacene thin film samples were fabricated and the degradation of their electrical characteristics was measured when the devices were exposed to ultraviolet light irradiation. The results have been reported in terms of a trap density model, which provides a description of the dynamics of light induced electrically active defects in an organic semiconductor.

  1. Defect suppression from the compound semiconductor heterointerfaces

    SciTech Connect (OSTI)

    Kalem, S. [TUBITAK-Marmara Research Center, Gebze (Turkey); Curtis, A.; Hartmann, Q.J.; Thomas, S.; Turnbull, D.; Chuang, H.; Bishop, S.G.; Stillman, G.E. [Univ. of Illinois, Urbana, IL (United States). Center for Compound Semiconductor Microelectronics

    1996-12-31T23:59:59.000Z

    The authors report on the effect of inserting ultra-thin InAs layers at the heterointerfaces on physical properties of GaAs/InGaP on GaAs and InP/GaAs on InP grown by MOCVD and MOMBE, respectively. It is shown that the insertion of ultra thin InAs layers at the heterostructure interfaces has a significant effect in eliminating defects from the interfaces.

  2. Topological defects and electronic properties in graphene

    E-Print Network [OSTI]

    Alberto Cortijo; María A. H. Vozmediano

    2006-12-14T23:59:59.000Z

    In this work we will focus on the effects produced by topological disorder on the electronic properties of a graphene plane. The presence of this type of disorder induces curvature in the samples of this material, making quite difficult the application of standard techniques of many body quantum theory. Once we understand the nature of these defects, we can apply ideas belonging to quantum field theory in curved space-time and extract information on physical properties that can be measured experimentally.

  3. Charged Local Defects in Extended Systems

    SciTech Connect (OSTI)

    Schultz, Peter A.

    1999-05-25T23:59:59.000Z

    The conventional approach to treating charged defects in extended systems in first principles calculations is via the supercell approximation using a neutralizing jellium background charge. I explicitly demonstrate shortcomings of this standard approach and discuss the consequences. Errors in the electrostatic potential surface over the volume of a supercell are shown to be comparable to a band gap energy in semiconductor materials, for cell sizes typically used in first principles simulations. I present an alternate method for eliminating the divergence of the Coulomb potential in supercell calculations of charged defects in extended systems that embodies a correct treatment of the electrostatic potential in the local viciniq of the a charged defect, via a mixed boundary condition approach. I present results of first principles calculations of charged vacancies in NaCl that illustrate the importance of polarization effects once an accurate representation of the local potential is obtained. These polarization effects, poorly captured in small supercells, also impact the energetic on the scale of typical band gap energies.

  4. Investigation of defect properties in Cu(In,Ga)Se2 solar cells by deep-level transient spectroscopy

    E-Print Network [OSTI]

    Anderson, Timothy J.

    mechanisms (and hence the minority-carrier lifetimes) in CIGS solar cells. Zhang [1] has calculatedInvestigation of defect properties in Cu(In,Ga)Se2 solar cells by deep-level transient spectroscopy cells. Three solar cells developed using different absorber growth technologies were analyzed using DLTS

  5. A single-molecule approach to ZnO defect studies: Single photons and single defects

    SciTech Connect (OSTI)

    Jungwirth, N. R.; Pai, Y. Y.; Chang, H. S.; MacQuarrie, E. R.; Nguyen, K. X.; Fuchs, G. D. [Cornell University, Ithaca, New York 14853 (United States)

    2014-07-28T23:59:59.000Z

    Investigations that probe defects one at a time offer a unique opportunity to observe properties and dynamics that are washed out of ensemble measurements. Here, we present confocal fluorescence measurements of individual defects in ZnO nanoparticles and sputtered films that are excited with sub-bandgap energy light. Photon correlation measurements yield both antibunching and bunching, indicative of single-photon emission from isolated defects that possess a metastable shelving state. The single-photon emission is in the range of ?560–720?nm and typically exhibits two broad spectral peaks separated by ?150?meV. The excited state lifetimes range from 1 to 13?ns, consistent with the finite-size and surface effects of nanoparticles and small grains. We also observe discrete jumps in the fluorescence intensity between a bright state and a dark state. The dwell times in each state are exponentially distributed and the average dwell time in the bright (dark) state does (may) depend on the power of the exciting laser. Taken together, our measurements demonstrate the utility of a single-molecule approach to semiconductor defect studies and highlight ZnO as a potential host material for single-defect based applications.

  6. Evolution of microstructural defects with strain effects in germanium nanocrystals synthesized at different annealing temperatures

    SciTech Connect (OSTI)

    Zhang, Minghuan; Cai, Rongsheng; Zhang, Yujuan; Wang, Chao [The Cultivation Base for State Key Laboratory, Qingdao University, No. 308, Ningxia Road, Qingdao 266071 (China); College of Chemistry and Chemical Engineering, Qingdao University, No. 308, Ningxia Road, Qingdao 266071 (China); Wang, Yiqian, E-mail: yqwang@qdu.edu.cn [The Cultivation Base for State Key Laboratory, Qingdao University, No. 308, Ningxia Road, Qingdao 266071 (China); College of Physics Science, Qingdao University, No. 308, Ningxia Road, Qingdao 266071 (China); Ross, Guy G.; Barba, David [INRS-EMT, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2 (Canada)

    2014-07-01T23:59:59.000Z

    Ge nanocrystals (Ge-ncs) were produced by implantation of {sup 74}Ge{sup +} into a SiO{sub 2} film on (100) Si, followed by high-temperature annealing from 700 °C to 1100 °C. Transmission electron microscopy (TEM) studies show that the average size of Ge-ncs increases with the annealing temperature. High-resolution TEM (HRTEM) investigations reveal the presence of planar and linear defects in the formed Ge-ncs, whose relative concentrations are determined at each annealing temperature. The relative concentration of planar defects is almost independent of the annealing temperature up to 1000 °C. However, from 1000 °C to 1100 °C, its concentration decreases dramatically. For the linear defects, their concentration varies considerably with the annealing temperatures. In addition, by measuring the interplanar spacing of Ge-ncs from the HRTEM images, a strong correlation is found between the dislocation percentage and the stress field intensity. Our results provide fundamental insights regarding both the presence of microstructural defects and the origin of the residual stress field within Ge-ncs, which can shed light on the fabrication of Ge-ncs with quantified crystallinity and appropriate size for the advanced Ge-nc devices. - Highlights: • Growth of Ge nanocrystals at different annealing temperatures was investigated. • Strain field has great effects on the formation of dislocations. • Different mechanisms are proposed to explain growth regimes of Ge nanocrystals.

  7. DFT+U Study of CeO2 and Its Native Defects

    E-Print Network [OSTI]

    Huang, Bolong; Gillen, Roland; Robertson, John

    2014-10-14T23:59:59.000Z

    in solid state fuel cells2, as a catalyst3-6, as a high-dielectric constant gate oxide7, and in resistance random access memories (ReRAM)8. Many properties of CeO2 are determined by its intrinsic defects9-23 and the unusual behavior of the semi-core Ce 4f... averaging scheme46 for spin- orbital coupling effect. The RRKJ method is chosen as optimization of pseudopotentials47. The PBE functional was chosen for PBE+U calculations with a kinetic cutoff energy of 750eV, which expands the valence electrons states...

  8. Method of identifying defective particle coatings

    DOE Patents [OSTI]

    Cohen, Mark E. (San Diego, CA); Whiting, Carlton D. (San Diego, CA)

    1986-01-01T23:59:59.000Z

    A method for identifying coated particles having defective coatings desig to retain therewithin a build-up of gaseous materials including: (a) Pulling a vacuum on the particles; (b) Backfilling the particles at atmospheric pressure with a liquid capable of wetting the exterior surface of the coated particles, said liquid being a compound which includes an element having an atomic number higher than the highest atomic number of any element in the composition which forms the exterior surface of the particle coating; (c) Drying the particles; and (d) Radiographing the particles. By television monitoring, examination of the radiographs is substantially enhanced.

  9. Understanding the Irradiation Behavior of Zirconium Carbide

    SciTech Connect (OSTI)

    Motta, Arthur; Sridharan, Kumar; Morgan, Dane; Szlufarska, Izabela

    2013-10-11T23:59:59.000Z

    Zirconium carbide (ZrC) is being considered for utilization in high-temperature gas-cooled reactor fuels in deep-burn TRISO fuel. Zirconium carbide possesses a cubic B1-type crystal structure with a high melting point, exceptional hardness, and good thermal and electrical conductivities. The use of ZrC as part of the TRISO fuel requires a thorough understanding of its irradiation response. However, the radiation effects on ZrC are still poorly understood. The majority of the existing research is focused on the radiation damage phenomena at higher temperatures (>450{degree}C) where many fundamental aspects of defect production and kinetics cannot be easily distinguished. Little is known about basic defect formation, clustering, and evolution of ZrC under irradiation, although some atomistic simulation and phenomenological studies have been performed. Such detailed information is needed to construct a model describing the microstructural evolution in fast-neutron irradiated materials that will be of great technological importance for the development of ZrC- based fuel. The goal of the proposed project is to gain fundamental understanding of the radiation-induced defect formation in zirconium carbide and irradiation response (ZrC) by using a combination of state-of-the-art experimental methods and atomistic modeling. This project will combine (1) in situ ion irradiation at a specialized facility at a national laboratory, (2) controlled temperature proton irradiation on bulk samples, and (3) atomistic modeling to gain a fundamental understanding of defect formation in ZrC. The proposed project will cover the irradiation temperatures from cryogenic temperature to as high as 800{degree}C, and dose ranges from 0.1 to 100 dpa. The examination of this wide range of temperatures and doses allows us to obtain an experimental data set that can be effectively used to exercise and benchmark the computer calculations of defect properties. Combining the examination of radiation-induced microstructures mapped spatially and temporally, microstructural evolution during post-irradiation annealing, and atomistic modeling of defect formation and transport energetics will provide new, critical understanding about property changes in ZrC. The behavior of materials under irradiation is determined by the balance between damage production, defect clustering, and lattice response. In order to predict those effects at high temperatures so targeted testing can be expanded and extrapolated beyond the known database, it is necessary to determine the defect energetics and mobilities as these control damage accumulation and annealing. In particular, low-temperature irradiations are invaluable for determining the regions of defect mobility. Computer simulation techniques are particularly useful for identifying basic defect properties, especially if closely coupled with a well-constructed and complete experimental database. The close coupling of calculation and experiment in this project will provide mutual benchmarking and allow us to glean a deeper understanding of the irradiation response of ZrC, which can then be applied to the prediction of its behavior in reactor conditions.

  10. MOSSBAUER STUDY OF Fe(ll) DOPED ALKALI CHLORIDE CRYSTALS AND DEFECT STRUCTURE Y. Takashima, N. Kai, T. Nishida and L. Chandler*

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    MOSSBAUER STUDY OF Fe(ll) DOPED ALKALI CHLORIDE CRYSTALS AND DEFECT STRUCTURE Y. Takashima, N. Kai-ray diffraction measurements and absorption Mossbauer spectroscopy, the behavior of the system especially related as being due to the substitution of Fe2+ for Li+ was observed in the Mossbauer spectrum. In the Na

  11. Formulas for the force dipole interaction of surface line defects in homoepitaxy This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Margetis, Dionisios

    decays as R-3 . This behavior is contrasted with the elastic interaction energy arising in heteroepitaxy of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About energy per unit length between line defects (steps) of the same sign that form perturbations of circles

  12. Computer programs for eddy-current defect studies

    SciTech Connect (OSTI)

    Pate, J. R.; Dodd, C. V. [Oak Ridge National Lab., TN (USA)

    1990-06-01T23:59:59.000Z

    Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.

  13. Physisorption of molecular hydrogen on carbon nanotube with vacant defects

    SciTech Connect (OSTI)

    Sun, Gang; Shen, Huaze; Wang, Enge; Xu, Limei, E-mail: limei.xu@pku.edu.cn [International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Tangpanitanon, Jirawat [University of Cambridge, Cambridge, Cambridgeshire CB2 1TP (United Kingdom); Wen, Bo [International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871 (China); Beijing Computational Science Research Center, Heqing Street, Haidian District, Beijing 100084 (China); Xue, Jianming [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)

    2014-05-28T23:59:59.000Z

    Physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) is important for its engineering applications and hydrogen energy storage. Using molecular dynamics simulation, we study the physisorption of molecular hydrogen on a SWCNT with a vacant defect, focusing on the effect of the vacant defect size and external parameters such as temperature and pressure. We find that hydrogen can be physisorbed inside a SWCNT through a vacant defect when the defect size is above a threshold. By controlling the size of the defects, we are able to extract hydrogen molecules from a gas mixture and store them inside the SWCNT. We also find that external parameters, such as low temperature and high pressure, enhance the physisorption of hydrogen molecules inside the SWCNT. In addition, the storage efficiency can be improved by introducing more defects, i.e., reducing the number of carbon atoms on the SWCNT.

  14. On the Defect Group of a 6D SCFT

    E-Print Network [OSTI]

    Michele Del Zotto; Jonathan J. Heckman; Daniel S. Park; Tom Rudelius

    2015-03-16T23:59:59.000Z

    We use the F-theory realization of 6D superconformal field theories (SCFTs) to study the corresponding spectrum of stringlike, i.e. surface defects. On the tensor branch, all of the stringlike excitations pick up a finite tension, and there is a corresponding lattice of string charges, as well as a dual lattice of charges for the surface defects. The defect group is data intrinsic to the SCFT and measures the surface defect charges which are not screened by dynamical strings. When non-trivial, it indicates that the associated theory has a partition vector rather than a partition function. We compute the defect group for all known 6D SCFTs, and find that it is just the abelianization of the discrete subgroup of U(2) which appears in the classification of 6D SCFTs realized in F-theory. We also explain how the defect group specifies defining data in the compactification of a (1,0) SCFT.

  15. IEEE TRANSACTIONS ON MAGNETICS, VOL. 40, NO. 1, JANUARY 2004 43 Mechanical Damage Detection With Magnetic

    E-Print Network [OSTI]

    Clapham, Lynann

    , stress. I. INTRODUCTION NONDESTRUCTIVE evaluation of in-service oil and gas pipelines by the magnetic to study MFL signals from corrosion pits [3]­[7]. Because these defects produce MFL signals mainly due pipe wall. In addition to corrosion defects, dents or "mechanical damage" in pipelines are also

  16. Simple intrinsic defects in GaAs : numerical supplement.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2012-04-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

  17. Irradiation-induced defect clustering and amorphization in silicon...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    guidance on experimental approaches to reveal the onset of these processes. Citation: Weber WJ, and F Gao.2010."Irradiation-induced defect clustering and amorphization in silicon...

  18. The case against scaling defect models of cosmic structure formation

    E-Print Network [OSTI]

    Andreas Albrecht; Richard A. Battye; James Robinson

    1997-07-11T23:59:59.000Z

    We calculate predictions from defect models of structure formation for both the matter and Cosmic Microwave Background (CMB) over all observable scales. Our results point to a serious problem reconciling the observed large-scale galaxy distribution with the COBE normalization, a result which is robust for a wide range of defect parameters. We conclude that standard scaling defect models are in conflict with the data, and show how attempts to resolve the problem by considering non-scaling defects would require radical departures from the standard scaling picture.

  19. Evolution equation of moving defects: dislocations and inclusions

    E-Print Network [OSTI]

    Markenscoff, Xanthippi

    2010-01-01T23:59:59.000Z

    9483-8 ORIGINAL PAPER Evolution equation of moving defects:Springerlink.com Abstract Evolution equations, or equationsof dissipation, and the evolution equation for a plane

  20. Pipe inspection method gives 3D view of OCTG defects

    SciTech Connect (OSTI)

    Kahil, J. (Baker Hughes Tubular Services, Houston, TX (US))

    1990-07-01T23:59:59.000Z

    A new technique for the nondestructive testing of tubulars is presented. It locates small or oblique defects that are currently going undetected.

  1. Sandia Energy - Research Challenge 4: Defect-Carrier Interactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    theoretical capabilities. We are using deep-level optical spectroscopy to quantify defect energy levels and densities. Advanced density functional theory is being used to predict...

  2. annealing radiation defects: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    is also investigated. Ionel Lazanu; Sorina Lazanu 2002-08-07 6 Radiation Damage in Silicon -Defect Analysis and Detector Properties - Physics Websites Summary:...

  3. Binding Energetics of Substitutional and Interstitial Helium and Di-Helium Defects with Grain Boundary Structure in alpha-Fe

    SciTech Connect (OSTI)

    Tschopp, Mark A.; Gao, Fei; Yang, Li; Solanki, K. N.

    2014-01-21T23:59:59.000Z

    he formation/binding energetics and length scales associated with the interaction between He atoms and grain boundaries in BCC alpha-Fe was explored. Ten different low grain boundaries from the <100> and <110> symmetric tilt sigma grain boundary systems were used. In this work, we then calculated formation/binding energies for 1 - 2 He atoms in the substitutional and interstitial sites (HeV, He2V, HeInt, He2Int) at all potential grain boundary sites within 15 °A of the boundary (52826 simulations total). The present results provide detailed information about the interaction energies and length scales of 1-2 He atoms with grain boundaries for the structures examined. A number of interesting new findings emerge from the present study. For instance, the sigma3(112) twin boundary in BCC Fe possesses a much smaller binding energy than other boundaries, which corresponds in long time dynamics simulations to the ability of an interstitial He defect to break away from the boundary in simulations on the order of nanoseconds. Additionally, positive correlations between the calculated formation/binding energies of the He defects (R > 0.9) asserts that the local environment surrounding each site strongly influences the He defect energies and that highly accurate quantum mechanics calculations of lower order defects may be an adequate predictor of higher order defects. Various metrics to quantify or classify the local environment were compared with the He defect binding energies. The present work shows that the binding and formation energies for He defects are important for understanding the physics of He diffusion and trapping by grain boundaries, which can be important for modeling He interactions in polycrystalline steels.

  4. Binding energetics of substitutional and interstitial helium and di-helium defects with grain boundary structure in ?-Fe

    SciTech Connect (OSTI)

    Tschopp, M. A., E-mail: mark.tschopp@gatech.edu [Dynamic Research Corporation, (on site at) U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); Center for Advanced Vehicular Systems, Mississippi State University, Starkville, Mississippi 39762 (United States); Gao, F.; Yang, L. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Solanki, K. N. [Arizona State University, School for Engineering of Matter, Transport and Energy, Tempe, Arizona 85287 (United States)

    2014-01-21T23:59:59.000Z

    The formation/binding energetics and length scales associated with the interaction between He atoms and grain boundaries in BCC ?-Fe were explored. Ten different low ? grain boundaries from the ?100? and ?110? symmetric tilt grain boundary systems were used. In this work, we then calculated formation/binding energies for 1–2 He atoms in the substitutional and interstitial sites (HeV, He{sub 2}V, HeInt, He{sub 2}Int) at all potential grain boundary sites within 15?Ĺ of the boundary (52?826 simulations total). The present results provide detailed information about the interaction energies and length scales of 1–2 He atoms with grain boundaries for the structures examined. A number of interesting new findings emerge from the present study. For instance, the ?3(112) twin boundary in BCC Fe possesses a much smaller binding energy than other boundaries, which corresponds in long time dynamics simulations to the ability of an interstitial He defect to break away from the boundary in simulations on the order of nanoseconds. Additionally, positive correlations between the calculated formation/binding energies of the He defects (R?>?0.9) asserts that the local environment surrounding each site strongly influences the He defect energies and that highly accurate quantum mechanics calculations of lower order defects may be an adequate predictor of higher order defects. Various metrics to quantify or classify the local environment were compared with the He defect binding energies. The present work shows that the binding and formation energies for He defects are important for understanding the physics of He diffusion and trapping by grain boundaries, which can be important for modeling He interactions in polycrystalline steels.

  5. The impact of trench defects in InGaN/GaN light emitting diodes and implications for the “green gap” problem

    SciTech Connect (OSTI)

    Massabuau, F. C.-P., E-mail: fm350@cam.ac.uk; Oehler, F.; Pamenter, S. K.; Thrush, E. J.; Kappers, M. J.; Humphreys, C. J.; Oliver, R. A. [Department of Materials Science and Metallurgy, University of Cambridge, 22 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Davies, M. J.; Dawson, P. [Photon Science Institute, School of Physics and Astronomy, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Kovács, A.; Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Leo-Brandt- Straße, D-52425 Jülich (Germany); Williams, T.; Etheridge, J. [Monash Centre for Electron Microscopy, Monash University, Clayton Campus, VIC 3800 (Australia); Hopkins, M. A.; Allsopp, D. W. E. [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-09-15T23:59:59.000Z

    The impact of trench defects in blue InGaN/GaN light emitting diodes (LEDs) has been investigated. Two mechanisms responsible for the structural degradation of the multiple quantum well (MQW) active region were identified. It was found that during the growth of the p-type GaN capping layer, loss of part of the active region enclosed within a trench defect occurred, affecting the top-most QWs in the MQW stack. Indium platelets and voids were also found to form preferentially at the bottom of the MQW stack. The presence of high densities of trench defects in the LEDs was found to relate to a significant reduction in photoluminescence and electroluminescence emission efficiency, for a range of excitation power densities and drive currents. This reduction in emission efficiency was attributed to an increase in the density of non-radiative recombination centres within the MQW stack, believed to be associated with the stacking mismatch boundaries which form part of the sub-surface structure of the trench defects. Investigation of the surface of green-emitting QW structures found a two decade increase in the density of trench defects, compared to its blue-emitting counterpart, suggesting that the efficiency of green-emitting LEDs may be strongly affected by the presence of these defects. Our results are therefore consistent with a model that the “green gap” problem might relate to localized strain relaxation occurring through defects.

  6. Vacancy-type defects in In{sub x}Ga{sub 1-x}N alloys probed using a monoenergetic positron beam

    SciTech Connect (OSTI)

    Uedono, A.; Watanabe, T. [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Ishibashi, S. [Nanosystem Research Institute (NRI) 'RICS,' National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Wang, X. Q.; Liu, S. T.; Chen, G.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Sang, L. W.; Sumiya, M. [Wide Bandgap Material Group, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan)

    2012-07-01T23:59:59.000Z

    Native defects in In{sub x}Ga{sub 1-x}N grown by plasma-assisted molecular beam epitaxy were probed by a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured, and these were compared with results obtained using first-principles calculation. The defect concentration increased with increasing In composition x and reached the maximum at x = 0.44{approx}0.56. A clear correlation between the line-width of photoluminescence and the defect concentration was obtained. The major defect species detected by positron annihilation was identified as cation vacancies coupled with multiple nitrogen vacancies (V{sub N}s), and their introduction mechanism is discussed in terms of the strain energy due to bond-length/angle distortions and the suppression of the V{sub N} formation energy by neighboring In atoms.

  7. Simple intrinsic defects in InAs : numerical predictions.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2013-03-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in indium arsenide, InAs, as computed by density functional theory using semi-local density functionals, intended for use as reference tables for a defect physics package in device models.

  8. Scattering of charge carriers in graphene induced by topological defects

    E-Print Network [OSTI]

    J. M. Fonseca; W. A. Moura-Melo; A. R. Pereira

    2011-08-04T23:59:59.000Z

    We study the scattering of graphene quasiparticles by topological defects, represented by holes, pentagons and heptagons. For holes, we found that at low concentration they give a negligible contribution to the resistivity. Whenever pentagons or heptagons are introduced we realize that a fermionic current is scattered by defects.

  9. Actinic characterization of EUV bump-type phase defects

    SciTech Connect (OSTI)

    Goldberg, Kenneth A.; Mochi, Iacopo; Liang, Ted

    2011-01-10T23:59:59.000Z

    Despite tremendous progress and learning with EUV lithography, quantitative experimental information about the severity of point-like phase defects remains in short supply. We present a study of measured, EUV aerial images from a series of well-characterized, open-field, bump-type programmed phase defects, created on a substrate before multilayer deposition.

  10. CHARACTERIZATION OF VIBRATIONINDUCED IMAGE DEFECTS IN INPUT SCANNERS

    E-Print Network [OSTI]

    Wolberg, George

    ) by dynamic errors of gears, timing bets, and motors, and indirectly by structural vibrations induced by gearsCHARACTERIZATION OF VIBRATION­INDUCED IMAGE DEFECTS IN INPUT SCANNERS Robert P. Loce George Wolberg. Keywords: image defects, digital documents, scanned documents, vibrations, motion quality 1. INTRODUCTION

  11. Built-In Self Test (BIST) for Realistic Delay Defects

    E-Print Network [OSTI]

    Tamilarasan, Karthik Prabhu

    2012-02-14T23:59:59.000Z

    with the insertion of test points, BIST is able to achieve high coverage of stuck-at and transition faults. The quality of BIST patterns on small delay defects is an open question. In this work we analyze the application of BIST to small delay defects using resistive...

  12. Defects activated photoluminescence in two-dimensional semiconductors

    E-Print Network [OSTI]

    Wu, Junqiao

    Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, People's Republic of China, 3, Berkeley, California 94720, United States. Point defects in semiconductors can trap free charge carriers

  13. Defect in lung growth* Comparative study of three diagnostic criteria.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Defect in lung growth* Comparative study of three diagnostic criteria. P. DECHELOTTE, A. LABBE, O and fetuses (49 pathological cases and 25 controls) to detect defects in lung growth. In each case lung disease. RA count is low in lung hypoplasia but is not an entirely reliable diagnostic criterion since

  14. Eddy Current Testing for Detecting Small Defects in Thin Films

    SciTech Connect (OSTI)

    Obeid, Simon; Tranjan, Farid M. [Electrical and Computer Engineering Department, UNCC (United States); Dogaru, Teodor [Albany Instruments, 426-O Barton Creek, Charlotte, NC 28262 (United States)

    2007-03-21T23:59:59.000Z

    Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.

  15. Disentangling defects and sound modes in disordered solids

    E-Print Network [OSTI]

    Sven Wijtmans; M. Lisa Manning

    2015-02-05T23:59:59.000Z

    We develop a new method to isolate localized defects from extended vibrational modes in disordered solids. This method augments particle interactions with an artificial potential that acts as a high-pass filter: it preserves small-scale structures while pushing extended vibrational modes to higher frequencies. The low-frequency modes that remain are "bare" defects; they are exponentially localized without the quadrupolar tails associated with elastic interactions. We identify a robust definition for the energy barrier associated with each defect, which is an important parameter in continuum models for plasticity. Surprisingly, we find that the energy barriers associated with "bare" defects are generally higher than those for defects decorated with elastic tails, suggesting that elastic interactions may help to constitutively activate particle rearrangements.

  16. Mechanical Properties and Radiation Tolerance of Ultrafine Grained and Nanocrystalline Metals

    E-Print Network [OSTI]

    Sun, Cheng

    2013-04-26T23:59:59.000Z

    loops. Here we provide experimental evidence that high angle grain boundaries can effectively remove radiation-induced defects. The equal channel angular pressing (ECAP) technique was used to produce ultrafine grained Fe-Cr-Ni alloy. Mechanical...

  17. Evolution of Frictional Behavior of Punchbowl Fault Gouges Sheared at Seismic Slip Rates and Mechanical and Hydraulic Properties of Nankai Trough Accretionary Prism Sediments Deformed at Different Loading Paths 

    E-Print Network [OSTI]

    Kitajima, Hiroko

    2012-02-14T23:59:59.000Z

    Frictional measurements were made on natural fault gouge at seismic slip rates using a high-speed rotary-shear apparatus to study effects of slip velocity, acceleration, displacement, normal stress, and water content. Thermal-, mechanical...

  18. & Mechanical Engineering

    E-Print Network [OSTI]

    Zhou, Chongwu

    , robotics, and the development of new tools for integrated approaches to concurrent engineeringAME Aerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex Engineering (AME) students conduct basic and applied research within and across the usual disciplinary

  19. Gate dielectric degradation: Pre-existing vs. generated defects

    SciTech Connect (OSTI)

    Veksler, Dmitry, E-mail: Dmitry.Veksler@sematech.org, E-mail: gennadi.bersuker@sematech.org; Bersuker, Gennadi, E-mail: Dmitry.Veksler@sematech.org, E-mail: gennadi.bersuker@sematech.org [SEMATECH Inc., 257 Fuller Rd., Albany, New York 12203 (United States)

    2014-01-21T23:59:59.000Z

    We consider the possibility that degradation of the electrical characteristics of high-k gate stacks under low voltage stresses of practical interest is caused primarily by activation of pre-existing defects rather than generation of new ones. In nFETs in inversion, in particular, defect activation is suggested to be associated with the capture of an injected electron: in this charged state, defects can participate in a fast exchange of charge carriers with the carrier reservoir (substrate or gate electrode) that constitutes the physical process underlying a variety of electrical measurements. The degradation caused by the activation of pre-existing defects, as opposed to that of new defect generation, is both reversible and exhibits a tendency to saturate through the duration of stress. By using the multi-phonon assisted charge transport description, it is demonstrated that the trap activation concept allows reproducing a variety of experimental results including stress time dependency of the threshold voltage, leakage current, charge pumping current, and low frequency noise. Continuous, long-term degradation described by the power law time dependency is shown to be determined by the activation of defects located in the interfacial SiO{sub 2} layer of the high-k gate stacks. The findings of this study can direct process optimization efforts towards reduction of as-grown precursors of the charge trapping defects as the major factor affecting reliability.

  20. Point defect balance in epitaxial GaSb

    SciTech Connect (OSTI)

    Segercrantz, N., E-mail: natalie.segercrantz@aalto.fi; Slotte, J.; Makkonen, I.; Kujala, J.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 14100, FIN-00076 Aalto Espoo (Finland); Song, Y.; Wang, S. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Göteborg (Sweden); State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences 865 Changning Road, Shanghai 200050 (China)

    2014-08-25T23:59:59.000Z

    Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.

  1. Probing graphene defects and estimating graphene quality with optical microscopy

    SciTech Connect (OSTI)

    Lai, Shen [SKKU Advanced Institute of Nanotechnology (SAINT), Suwon 440-746 (Korea, Republic of); Center for Human Interface Nanotechnology (HINT), Suwon 440-746 (Korea, Republic of); Kyu Jang, Sung [SKKU Advanced Institute of Nanotechnology (SAINT), Suwon 440-746 (Korea, Republic of); Jae Song, Young, E-mail: yjsong@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT), Suwon 440-746 (Korea, Republic of); Department of Physics, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea, Republic of); Lee, Sungjoo, E-mail: leesj@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT), Suwon 440-746 (Korea, Republic of); Center for Human Interface Nanotechnology (HINT), Suwon 440-746 (Korea, Republic of); College of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea, Republic of)

    2014-01-27T23:59:59.000Z

    We report a simple and accurate method for detecting graphene defects that utilizes the mild, dry annealing of graphene/Cu films in air. In contrast to previously reported techniques, our simple approach with optical microscopy can determine the density and degree of dislocation of defects in a graphene film without inducing water-related damage or functionalization. Scanning electron microscopy, confocal Raman and atomic force microscopy, and X-ray photoelectron spectroscopy analysis were performed to demonstrate that our nondestructive approach to characterizing graphene defects with optimized thermal annealing provides rapid and comprehensive determinations of graphene quality.

  2. Carbonation Mechanism of Reservoir Rock by Supercritical Carbon...

    Open Energy Info (EERE)

    Task 3: Mechanical behaviors of carbonated minerals. - Task 4: Modeling of CO2- reservoir rock interactions. - Task 5: Preparation of report covering the four tasks previous task,...

  3. Do the Defects Make It Work? Defect Engineering in Pi-Conjugated Polymers and Their Solar Cells: Preprint

    SciTech Connect (OSTI)

    Wang, D.; Reese, M.; Kopidakis N.; Gregg, B. A.

    2008-05-01T23:59:59.000Z

    The charged defect density in common pi-conjugated polymers such as poly(3-hexylthiophene), P3HT, is around 1018 cm-3. Despite, or perhaps because of, this huge defect density, bulk heterojunction solar cells made from these polymers and a C60 derivative such as PCBM exhibit some of the highest efficiencies (~5%) yet obtained in solid state organic photovoltaic cells. We discuss defects in molecular organic semiconductors and in pi-conjugated polymers. These defects can be grouped in two categories, covalent and noncovalent. Somewhat analogous to treating amorphous silicon with hydrogen, we introduce chemical methods to modify the density and charge of the covalent defects in P3HT by treating it with electrophiles such as dimethyl sulfate and nucleophiles such as sodium methoxide. The effects of these treatments on the electrical and photovoltaic properties and stability of organic PV cells is discussed in terms of the change in the number and chemical properties of the defects. Finally, we address the question of whether the efficiency of OPV cells requires the presence of these defects which function as adventitious p-type dopants. Their presence relieves the resistance limitations usually encountered in cleaner organic semiconductors and can create built-in electric fields at junctions.

  4. Defect reaction network in Si-doped InP : numerical predictions.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2013-10-01T23:59:59.000Z

    This Report characterizes the defects in the defect reaction network in silicon-doped, n-type InP deduced from first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si-doped InP until culminating in immobile reaction products. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon-related defects in the reaction network. This Report serves to extend the results for intrinsic defects in SAND 2012-3313: %E2%80%9CSimple intrinsic defects in InP: Numerical predictions%E2%80%9D to include Si-containing simple defects likely to be present in a radiation-induced defect reaction sequence.

  5. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide

    SciTech Connect (OSTI)

    Jiang, Weilin; Jung, Hee Joon; Kovarik, Libor; Wang, Zhaoying; Roosendaal, Timothy J.; Zhu, Zihua; Edwards, Danny J.; Hu, Shenyang Y.; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2015-01-01T23:59:59.000Z

    As a candidate material for fusion reactor applications, silicon carbide (SiC) undergoes transmutation reactions under high-energy neutron irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. The impact of these transmutants on SiC structural stability is currently unknown. This study uses ion implantation to introduce Mg into SiC. Multiaxial ion-channeling analysis of the as-produced damage state suggests that there are preferred Si <100> interstitial splits. The microstructure of the annealed sample was examined using high-resolution scanning transmission electron microscopy. The results show a high concentration of likely non-faulted tetrahedral voids and possible stacking fault tetrahedra near the damage peak. In addition to lattice distortion, dislocations and intrinsic and extrinsic stacking faults are also observed. Magnesium in 3C-SiC prefers to substitute for Si and it forms precipitates of cubic Mg2Si and tetragonal MgC2. The diffusion coefficient of Mg in 3C-SiC single crystal at 1573 K has been determined to be 3.8±0.4×10e-19 m2/sec.

  6. Topological defect motifs in two-dimensional Coulomb clusters

    E-Print Network [OSTI]

    Radzvilavi?ius, A; 10.1088/0953-8984/23/38/385301

    2012-01-01T23:59:59.000Z

    The most energetically favourable arrangement of low-density electrons in an infinite two-dimensional plane is the ordered triangular Wigner lattice. However, in most instances of contemporary interest one deals instead with finite clusters of strongly interacting particles localized in potential traps, for example, in complex plasmas. In the current contribution we study distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analyzed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size and the energetic state. Besides isolated disclinations and dislocations, classification of defect motifs includes defect compounds --- grain boundaries, rosette defects, vacancies and interstitial particles. Proliferatio...

  7. Design and process solutions for decreasing vendor defects

    E-Print Network [OSTI]

    Joyce, Michael (Michael Sagar)

    2013-01-01T23:59:59.000Z

    Why do some new initiatives fail while others succeed? This thesis attempts to answer this complex question by investigating the failure of a defect tracking initiative at Amazon and examining how a reintroduction of the ...

  8. Wave propagation in periodic lattices with defects of smaller dimension

    E-Print Network [OSTI]

    A. A. Kutsenko

    2013-05-20T23:59:59.000Z

    The procedure of evaluating of the spectrum for discrete periodic operators perturbed by operators of smaller dimensions is obtained. This result allows to obtain propagative, guided, localised spectra for different kind of physical operators on graphs with defects.

  9. Defect specific maintenance of SG tubes -- How safe is it?

    SciTech Connect (OSTI)

    Cizelj, L.; Mavko, B.; Dvorsek, T. [Jozef Stefan Institute, Ljubljana (Slovenia)

    1997-02-01T23:59:59.000Z

    The efficiency of the defect specific plugging criterion for outside diameter stress corrosion cracking at tube support plates is assessed. The efficiency is defined by three parameters: (1) number of plugged tubes, (2) probability of steam generator tube rupture and (3) predicted accidental leak rate through the defects. A probabilistic model is proposed to quantify the probability of tube rupture, while procedures available in literature were used to define the accidental leak rates. The defect specific plugging criterion was then compared to the performance of traditional (45%) plugging criterion using realistic data from Krsko nuclear power plant. Advantages of the defect specific approach over the traditional one are clearly shown. Some hints on the optimization of safe life of steam generator are also given.

  10. Method and apparatus for inspecting reflection masks for defects

    DOE Patents [OSTI]

    Bokor, Jeffrey (Oakland, CA); Lin, Yun (Berkeley, CA)

    2003-04-29T23:59:59.000Z

    An at-wavelength system for extreme ultraviolet lithography mask blank defect detection is provided. When a focused beam of wavelength 13 nm is incident on a defective region of a mask blank, three possible phenomena can occur. The defect will induce an intensity reduction in the specularly reflected beam, scatter incoming photons into an off-specular direction, and change the amplitude and phase of the electric field at the surface which can be monitored through the change in the photoemission current. The magnitude of these changes will depend on the incident beam size, and the nature, extent and size of the defect. Inspection of the mask blank is performed by scanning the mask blank with 13 nm light focused to a spot a few .mu.m in diameter, while measuring the reflected beam intensity (bright field detection), the scattered beam intensity (dark-field detection) and/or the change in the photoemission current.

  11. Liability for Defective Documentation FloridaInstitute of Technology

    E-Print Network [OSTI]

    Liability for Defective Documentation Cem Kaner FloridaInstitute of Technology 150 West University behind its claims. False claims in documentation might subject the manufacturer to liability for breach Engineering]: Distribution, Maintenance and Enhancement ­ documentation. General Terms Documentation, Human

  12. New Composite Silicon-Defect Graphene Anode Architecture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A New Composite Silicon-Defect Graphene Anode Architecture for High Capacity, High-Rate Li-ion Batteries Xin Zhao, Cary Hayner, Mayfair Kung, and Harold Kung, Northwestern...

  13. Defects and impurities in graphene-like materials

    E-Print Network [OSTI]

    Terrones, Mauricio

    Graphene-like materials could be used in the fabrication of electronic and optoelectronic devices, gas sensors, biosensors, and batteries for energy storage. Since it is almost impossible to work with defect-free or ...

  14. Built-In Self Test (BIST) for Realistic Delay Defects 

    E-Print Network [OSTI]

    Tamilarasan, Karthik Prabhu

    2012-02-14T23:59:59.000Z

    Testing of delay defects is necessary in deep submicron (DSM) technologies. High coverage delay tests produced by automatic test pattern generation (ATPG) can be applied during wafer and package tests, but are difficult ...

  15. Quality improvement and control based on defect reduction

    E-Print Network [OSTI]

    Dai, Qi, M. Eng. Massachusetts Institute of Technology

    2010-01-01T23:59:59.000Z

    This thesis addresses the quality improvement in a printing process at a food packaging company now experiencing hundreds of printing defects. Methodologies of Define, Measure, Analyze, Improve, and Control (DMAIC), and ...

  16. Role of fluctuations and defects in select condensed matter problems

    E-Print Network [OSTI]

    Pressé, Steve, 1981-

    2008-01-01T23:59:59.000Z

    Defects and fluctuations dominate both static and dynamical properties of systems in the condensed phase. In this work, we focus on three such examples. Firstly, we model the effect of proton fluctuations on the rate of ...

  17. Spin properties of very shallow nitrogen vacancy defects in diamond

    E-Print Network [OSTI]

    Ofori-Okai, Benjamin Kwasi

    We investigate spin and optical properties of individual nitrogen vacancy centers located within 1–10 nm from the diamond surface. We observe stable defects with a characteristic optically detected magnetic-resonance ...

  18. Sandia National Laboratories: Research Challenge 4: Defect-Carrier...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    edge. Note that the density is much higher in the rightmost QW1 closest to the n-type GaN region. Our study of defects involves unique experimental and theoretical capabilities....

  19. Heavy and Overweight Vehicle Defects Interim Report

    SciTech Connect (OSTI)

    Siekmann, Adam [ORNL; Capps, Gary J [ORNL

    2012-12-01T23:59:59.000Z

    The Federal Highway Administration (FHWA), along with the Federal Motor Carrier Safety Administration (FMCSA), has an interest in overweight commercial motor vehicles, how they affect infrastructure, and their impact on safety on the nation s highways. To assist both FHWA and FMCSA in obtaining more information related to this interest, data was collected and analyzed from two separate sources. A large scale nationwide data collection effort was facilitated by the Commercial Vehicle Safety Alliance as part of a special study on overweight vehicles and an additional, smaller set, of data was collected from the state of Tennessee which included a much more detailed set of data. Over a six-month period, 1,873 Level I inspections were performed in 18 different states that volunteered to be a part of this study. Of the 1,873 inspections, a vehicle out-of-service (OOS) violation was found on 44.79% of the vehicles, a rate significantly higher than the national OOS rate of 27.23%. The main cause of a vehicle being placed OOS was brake-related defects, with approximately 30% of all vehicles having an OOS brake violation. Only about 4% of vehicles had an OOS tire violation, and even fewer had suspension and wheel violations. Vehicle weight violations were most common on an axle group as opposed to a gross vehicle weight violation. About two thirds of the vehicles cited with a weight violation were overweight on an axle group with an average amount of weight over the legal limit of about 2,000 lbs. Data collection is scheduled to continue through January 2014, with more potentially more states volunteering to collect data. More detailed data collections similar to the Tennessee data collection will also be performed in multiple states.

  20. Luminescence properties of defects in GaN

    SciTech Connect (OSTI)

    Reshchikov, Michael A.; Morkoc, Hadis [Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)

    2005-03-15T23:59:59.000Z

    Gallium nitride (GaN) and its allied binaries InN and AIN as well as their ternary compounds have gained an unprecedented attention due to their wide-ranging applications encompassing green, blue, violet, and ultraviolet (UV) emitters and detectors (in photon ranges inaccessible by other semiconductors) and high-power amplifiers. However, even the best of the three binaries, GaN, contains many structural and point defects caused to a large extent by lattice and stacking mismatch with substrates. These defects notably affect the electrical and optical properties of the host material and can seriously degrade the performance and reliability of devices made based on these nitride semiconductors. Even though GaN broke the long-standing paradigm that high density of dislocations precludes acceptable device performance, point defects have taken the center stage as they exacerbate efforts to increase the efficiency of emitters, increase laser operation lifetime, and lead to anomalies in electronic devices. The point defects include native isolated defects (vacancies, interstitial, and antisites), intentional or unintentional impurities, as well as complexes involving different combinations of the isolated defects. Further improvements in device performance and longevity hinge on an in-depth understanding of point defects and their reduction. In this review a comprehensive and critical analysis of point defects in GaN, particularly their manifestation in luminescence, is presented. In addition to a comprehensive analysis of native point defects, the signatures of intentionally and unintentionally introduced impurities are addressed. The review discusses in detail the characteristics and the origin of the major luminescence bands including the ultraviolet, blue, green, yellow, and red bands in undoped GaN. The effects of important group-II impurities, such as Zn and Mg on the photoluminescence of GaN, are treated in detail. Similarly, but to a lesser extent, the effects of other impurities, such as C, Si, H, O, Be, Mn, Cd, etc., on the luminescence properties of GaN are also reviewed. Further, atypical luminescence lines which are tentatively attributed to the surface and structural defects are discussed. The effect of surfaces and surface preparation, particularly wet and dry etching, exposure to UV light in vacuum or controlled gas ambient, annealing, and ion implantation on the characteristics of the defect-related emissions is described.

  1. Plug Load Behavioral Change Demonstration Project

    SciTech Connect (OSTI)

    Metzger, I.; Kandt, A.; VanGeet, O.

    2011-08-01T23:59:59.000Z

    This report documents the methods and results of a plug load study of the Environmental Protection Agency's Region 8 Headquarters in Denver, Colorado, conducted by the National Renewable Energy Laboratory. The study quantified the effect of mechanical and behavioral change approaches on plug load energy reduction and identified effective ways to reduce plug load energy. Load reduction approaches included automated energy management systems and behavioral change strategies.

  2. Ultrasonic Tomography for Detecting and Locating Defects in Concrete Structures

    E-Print Network [OSTI]

    White, Joshua

    2012-07-16T23:59:59.000Z

    ....................................................... 18 Figure 6 Typical C-scans for simulated defects in shotcrete slabs: Specimens D, E, I, and M ............................................................................................... 19 Figure 7 Clay lump slab construction... and shotcrete s labs. Figs. 5 and 6 delaminations, are shown in Figs. 5 and 6. The images in these figures are representative 19 19 Fig. 6. Typical C-scans for simulated defects in shotcrete slabs: Specimens D (top left), E (top right), I (bottom...

  3. Relative projective cover works for Broue's abelian defect group

    E-Print Network [OSTI]

    Thévenaz, Jacques

    University, Chiba, Japan Tue. 22 June, 2010 Joint work with J¨urgen M¨uller and Felix Noeske Brou´e's abelian that A is a block algebra of OG with a defect group P and that AN is a block algebra of ONG(P) which is the Brauer´e's abelian defect group conjecture holds for all primes p and for all block algebras of OG if G = Co3, where

  4. Graphene materials having randomly distributed two-dimensional structural defects

    DOE Patents [OSTI]

    2013-10-08T23:59:59.000Z

    Graphene-based storage materials for high-power battery applications are provided. The storage materials are composed of vertical stacks of graphene sheets and have reduced resistance for Li ion transport. This reduced resistance is achieved by incorporating a random distribution of structural defects into the stacked graphene sheets, whereby the structural defects facilitate the diffusion of Li ions into the interior of the storage materials.

  5. Continuous-Wave Radar to Detect Defects Within Heat Exchangers and Steam Generator Tubes ; Revised September 3, 2003

    SciTech Connect (OSTI)

    Gary E. Rochau and Thurlow W.H. Caffey, Sandia National Laboratories, Albuquerque, NM 87185-0740; Bahram Nassersharif and Gabe V. Garcia, Department of Mechanical Engineering, New Mexico State University, Las Cruces, NM 88003-8001; Russell P. Jedlicka, Klipsch School of Electrical and Computer Engineering, New Mexico State University, Las Cruces, NM 88003-8001

    2003-05-01T23:59:59.000Z

    OAK B204 Continuous-Wave Radar to Detect Defects Within Heat Exchangers and Steam Generator Tubes ; Revised September 3, 2003. A major cause of failures in heat exchangers and steam generators in nuclear power plants is degradation of the tubes within them. The tube failure is often caused by the development of cracks that begin on the outer surface of the tube and propagate both inwards and laterally. A new technique was researched for detection of defects using a continuous-wave radar method within metal tubing. The technique is 100% volumetric, and may find smaller defects, more rapidly, and less expensively than present methods. The project described in this report was a joint development effort between Sandia National Laboratories (SNL) and New Mexico State University (NMSU) funded by the US Department of Energy. The goal of the project was to research, design, and develop a new concept utilizing a continuous wave radar to detect defects inside metallic tubes and in particular nuclear plant steam generator tubing. The project was divided into four parallel tracks: computational modeling, experimental prototyping, thermo-mechanical design, and signal detection and analysis.

  6. Crystal defect studies using x-ray diffuse scattering

    SciTech Connect (OSTI)

    Larson, B.C.

    1980-01-01T23:59:59.000Z

    Microscopic lattice defects such as point (single atom) defects, dislocation loops, and solute precipitates are characterized by local electronic density changes at the defect sites and by distortions of the lattice structure surrounding the defects. The effect of these interruptions of the crystal lattice on the scattering of x-rays is considered in this paper, and examples are presented of the use of the diffuse scattering to study the defects. X-ray studies of self-interstitials in electron irradiated aluminum and copper are discussed in terms of the identification of the interstitial configuration. Methods for detecting the onset of point defect aggregation into dislocation loops are considered and new techniques for the determination of separate size distributions for vacancy loops and interstitial loops are presented. Direct comparisons of dislocation loop measurements by x-rays with existing electron microscopy studies of dislocation loops indicate agreement for larger size loops, but x-ray measurements report higher concentrations in the smaller loop range. Methods for distinguishing between loops and three-dimensional precipitates are discussed and possibilities for detailed studies considered. A comparison of dislocation loop size distributions obtained from integral diffuse scattering measurements with those from TEM show a discrepancy in the smaller sizes similar to that described above.

  7. A detail study of defect models for cosmic structure formation

    E-Print Network [OSTI]

    A. Albrecht; R. A. Battye; J. Robinson

    1997-11-27T23:59:59.000Z

    We calculate predictions from wide class of `active' models of cosmic structure formation which allows us to scan the space of possible defect models. We calculate the linear cold dark matter power spectrum and Cosmic Microwave Background (CMB) anisotropies over all observable scales using a full linear Einstein-Boltzmann code. Our main result, which has already been reported, points to a serious problem reconciling the observed amplitude of the large-scale galaxy distribution with the COBE normalization. Here, we describe our methods and results in detail. The problem is present for a wide range of defect parameters, which can be used to represent potential differences among defect models, as well as possible systematic numerical errors. We explicitly examine the impact of varying the defect model parameters and we show how the results substantiate these conclusions. The standard scaling defect models are in serious conflict with the current data, and we show how attempts to resolve the problem by considering non-scaling defects or modified stress-energy components would require radical departures from what has become the standard picture.

  8. Toolkit for Teaching Steering Behaviors for 3D Human-like Virtual Agents (Demonstration)

    E-Print Network [OSTI]

    Brom, Cyril

    of steering behaviors for Pogamut toolkit for developing control mechanisms of virtual agents. The second one]: Model Development General Terms Algorithms Keywords Steering behaviors, Human-like virtual agents behavior shows that steering behaviors may not only control low-level navigation, but they may also be used

  9. Context-based automated defect classification system using multiple morphological masks

    DOE Patents [OSTI]

    Gleason, Shaun S. (Knoxville, TN); Hunt, Martin A. (Knoxville, TN); Sari-Sarraf, Hamed (Lubbock, TX)

    2002-01-01T23:59:59.000Z

    Automatic detection of defects during the fabrication of semiconductor wafers is largely automated, but the classification of those defects is still performed manually by technicians. This invention includes novel digital image analysis techniques that generate unique feature vector descriptions of semiconductor defects as well as classifiers that use these descriptions to automatically categorize the defects into one of a set of pre-defined classes. Feature extraction techniques based on multiple-focus images, multiple-defect mask images, and segmented semiconductor wafer images are used to create unique feature-based descriptions of the semiconductor defects. These feature-based defect descriptions are subsequently classified by a defect classifier into categories that depend on defect characteristics and defect contextual information, that is, the semiconductor process layer(s) with which the defect comes in contact. At the heart of the system is a knowledge database that stores and distributes historical semiconductor wafer and defect data to guide the feature extraction and classification processes. In summary, this invention takes as its input a set of images containing semiconductor defect information, and generates as its output a classification for the defect that describes not only the defect itself, but also the location of that defect with respect to the semiconductor process layers.

  10. Systems and methods for forming defects on graphitic materials and curing radiation-damaged graphitic materials

    DOE Patents [OSTI]

    Ryu, Sunmin; Brus, Louis E.; Steigerwald, Michael L.; Liu, Haitao

    2012-09-25T23:59:59.000Z

    Systems and methods are disclosed herein for forming defects on graphitic materials. The methods for forming defects include applying a radiation reactive material on a graphitic material, irradiating the applied radiation reactive material to produce a reactive species, and permitting the reactive species to react with the graphitic material to form defects. Additionally, disclosed are methods for removing defects on graphitic materials.

  11. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01T23:59:59.000Z

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

  12. Electroluminescence from isolated defects in zinc oxide, towards electrically triggered single photon sources at room temperature

    E-Print Network [OSTI]

    Choi, Sumin; Gentle, Angus; Ton-That, Cuong; Phillips, Matthew R; Aharonovich, Igor

    2015-01-01T23:59:59.000Z

    Single photon sources are required for a wide range of applications in quantum information science, quantum cryptography and quantum communications. However, so far majority of room temperature emitters are only excited optically, which limits their proper integration into scalable devices. In this work, we overcome this limitation and present room temperature electrically triggered light emission from localized defects in zinc oxide (ZnO) nanoparticles and thin films. The devices emit at the red spectral range and show excellent rectifying behavior. The emission is stable over an extensive period of time, providing an important prerequisite for practical devices. Our results open up possibilities to build new ZnO based quantum integrated devices that incorporate solid-state single photon sources for quantum information technologies.

  13. Defects and persistent conductivity in SrTiO{sub 3}

    SciTech Connect (OSTI)

    McCluskey, Matthew D.; Tarun, Marianne C. [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814 (United States)

    2014-02-21T23:59:59.000Z

    Strontium titanate (SrTiO{sub 3}) is often used as a substrate for oxide thin films such as high-temperature superconductors. It has the perovskite structure and an indirect band gap of 3.25 eV. Our prior work showed that hydrogen impurities form a defect complex that contains two hydrogen atoms. The complex was tentatively attributed to a passivated strontium vacancy. Alternatively, it could be a partially passivated titanium vacancy. In order to create titanium vacancies, we annealed samples in an evacuated ampoule with SrO powder. These samples show unexpected behavior. After illuminating with sub-gap light, the free-electron concentration increases significantly. After the light is turned off, the high conductivity persists at room temperature. We attribute persistent photoconductivity (PPC) to the excitation of an electron from a vacancy into the conduction band, with a low recapture rate.

  14. Radiative defects in GaN nanocolumns: Correlation with growth conditions and sample morphology

    SciTech Connect (OSTI)

    Lefebvre, P.; Fernandez-Garrido, S.; Grandal, J.; Ristic, J.; Sanchez-Garcia, M.-A.; Calleja, E. [Instituto de Sistemas Optoelectronicos y Microtecnologia, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2011-02-21T23:59:59.000Z

    Low-temperature photoluminescence is studied in detail in GaN nanocolumns (NCs) grown by plasma-assisted molecular beam epitaxy under various conditions (substrate temperature and impinging Ga/N flux ratio). The relative intensities of the different emission lines, in particular those related to structural defects, appear to be correlated with the growth conditions, and clearly linked to the NC sample morphology. We demonstrate, in particular, that all lines comprised between 3.10 and 3.42 eV rapidly lose intensity when the growth conditions are such that the NC coalescence is reduced. The well-known line around 3.45 eV, characteristic of GaN NC samples, shows, however, a behavior that is exactly the opposite of the other lines, namely, for growth conditions leading to reduced NC coalescence, this line tends to become more prominent, thus proving to be intrinsic to individual GaN NCs.

  15. Mechanical instability at finite temperature

    E-Print Network [OSTI]

    Xiaoming Mao; Anton Souslov; Carlos I. Mendoza; T. C. Lubensky

    2014-07-08T23:59:59.000Z

    Many physical systems including lattices near structural phase transitions, glasses, jammed solids, and bio-polymer gels have coordination numbers that place them at the edge of mechanical instability. Their properties are determined by an interplay between soft mechanical modes and thermal fluctuations. In this paper we investigate a simple square-lattice model with a $\\phi^4$ potential between next-nearest-neighbor sites whose quadratic coefficient $\\kappa$ can be tuned from positive negative. We show that its zero-temperature ground state for $\\kappa power-law behavior of the shear modulus as a function of temperature. We expect our study to provide a general framework for the study of finite-temperature mechanical and phase behavior of other systems with a large number of floppy modes.

  16. On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

    SciTech Connect (OSTI)

    Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager III, Joel W.; Ritchie, Robert O.

    2010-01-10T23:59:59.000Z

    In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the progressive elimination of the bone's capacity for plastic deformation which restricts the intrinsic toughening from the formation 'plastic zones' around crack-like defects. Deep-ultraviolet Raman spectroscopy indicated that this behavior could be related to degradation in the collagen integrity.

  17. Predicting the Occurrence of Cosmetic Defects in Automotive Skin Panels

    SciTech Connect (OSTI)

    Hazra, S.; Williams, D.; Roy, R. [University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Aylmore, R.; Allen, M.; Hollingdale, D. [Land Rover, Banbury Rd, Gaydon, Warwick, CV35 0RR (United Kingdom)

    2011-05-04T23:59:59.000Z

    The appearance of defects such as 'hollows' and 'shock lines' can affect the perceived quality and attractiveness of automotive skin panels. These defects are the result of the stamping process and appear as small, localized deviations from the intended styling of the panels. Despite their size, they become visually apparent after the application of paint and the perceived quality of a panel may become unacceptable. Considerable time is then dedicated to minimizing their occurrence through tool modifications. This paper will investigate the use of the wavelet transform as a tool to analyze physically measured panels. The transform has two key aspects. The first is its ability to distinguish small scale local defects from large scale styling curvature. The second is its ability to characterize the shape of a defect in terms of its wavelength and a 'correlation value'. The two features of the transform enable it to be used as a tool for locating and predicting the severity of defects. The paper will describe the transform and illustrate its application on test cases.

  18. Developmental defects in zebrafish for classification of EGF pathway inhibitors

    SciTech Connect (OSTI)

    Pruvot, Benoist; Curé, Yoann; Djiotsa, Joachim; Voncken, Audrey; Muller, Marc, E-mail: m.muller@ulg.ac.be

    2014-01-15T23:59:59.000Z

    One of the major challenges when testing drug candidates targeted at a specific pathway in whole animals is the discrimination between specific effects and unwanted, off-target effects. Here we used the zebrafish to define several developmental defects caused by impairment of Egf signaling, a major pathway of interest in tumor biology. We inactivated Egf signaling by genetically blocking Egf expression or using specific inhibitors of the Egf receptor function. We show that the combined occurrence of defects in cartilage formation, disturbance of blood flow in the trunk and a decrease of myelin basic protein expression represent good indicators for impairment of Egf signaling. Finally, we present a classification of known tyrosine kinase inhibitors according to their specificity for the Egf pathway. In conclusion, we show that developmental indicators can help to discriminate between specific effects on the target pathway from off-target effects in molecularly targeted drug screening experiments in whole animal systems. - Highlights: • We analyze the functions of Egf signaling on zebrafish development. • Genetic blocking of Egf expression causes cartilage, myelin and circulatory defects. • Chemical inhibition of Egf receptor function causes similar defects. • Developmental defects can reveal the specificity of Egf pathway inhibitors.

  19. Regulation mechanisms in spatial stochastic development models

    E-Print Network [OSTI]

    Dmitri Finkelshtein; Yuri Kondratiev

    2008-09-04T23:59:59.000Z

    The aim of this paper is to analyze different regulation mechanisms in spatial continuous stochastic development models. We describe the density behavior for models with global mortality and local establishment rates. We prove that the local self-regulation via a competition mechanism (density dependent mortality) may suppress a unbounded growth of the averaged density if the competition kernel is superstable.

  20. Correlation between the electronic structures and diffusion paths of interstitial defects in semiconductors: The case in CdTe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ma, Jie; Yang, Jihui; Da Silva, J. L.F.; Wei, Su-Huai

    2014-10-01T23:59:59.000Z

    Using first-principles calculations, we study the diffusions of interstitial defects Cd, Cu, Te, and Cl in CdTe. We find that the diffusion behavior is strongly correlated with the electronic structure of the interstitial diffuser. For Cd and Cu, because the defect state is the non-degenerated slike state under Td symmetry, the diffusions are almost along the [111] directions between the tetrahedral sites, although the diffusion of Cu shows some deviation due to the s - d coupling. The diffusions of the neutral and charged Cd and Cu follow similar paths. However, for Te and Cl atoms, because the defect statemore »is the degenerated p-like state under Td symmetry, large distortions occur. Therefore, the diffusion paths are very different from those of Cd and Cu interstitials, and depend strongly on the charge states of the interstitial atoms. For Te, we find that the distortion is mostly stabilized by the crystal-field splitting, but for Cl, the exchange splitting plays a more important role.« less

  1. Correlation between the electronic structures and diffusion paths of interstitial defects in semiconductors: The case in CdTe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ma, Jie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yang, Jihui [National Renewable Energy Lab. (NREL), Golden, CO (United States); Da Silva, J. L.F. [Univ. of Sao Paulo, Sao Carlos (Brazil). Sao Carlos Institute of Chemistry; Wei, Su-Huai [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2014-10-01T23:59:59.000Z

    Using first-principles calculations, we study the diffusions of interstitial defects Cd, Cu, Te, and Cl in CdTe. We find that the diffusion behavior is strongly correlated with the electronic structure of the interstitial diffuser. For Cd and Cu, because the defect state is the non-degenerated slike state under Td symmetry, the diffusions are almost along the [111] directions between the tetrahedral sites, although the diffusion of Cu shows some deviation due to the s - d coupling. The diffusions of the neutral and charged Cd and Cu follow similar paths. However, for Te and Cl atoms, because the defect state is the degenerated p-like state under Td symmetry, large distortions occur. Therefore, the diffusion paths are very different from those of Cd and Cu interstitials, and depend strongly on the charge states of the interstitial atoms. For Te, we find that the distortion is mostly stabilized by the crystal-field splitting, but for Cl, the exchange splitting plays a more important role.

  2. Nanocrystalline alloys : enhanced strengthening mechanisms and mechanically-driven structural evolution

    E-Print Network [OSTI]

    Rupert, Timothy J. (Timothy John)

    2011-01-01T23:59:59.000Z

    Nanocrystalline materials have experienced a great deal of attention in recent years, largely due to their impressive array of physical properties. In particular, nanocrystalline mechanical behavior has been of interest, ...

  3. Deformation Behavior of Nanoporous Metals

    SciTech Connect (OSTI)

    Biener, J; Hodge, A M; Hamza, A V

    2007-11-28T23:59:59.000Z

    Nanoporous open-cell foams are a rapidly growing class of high-porosity materials (porosity {ge} 70%). The research in this field is driven by the desire to create functional materials with unique physical, chemical and mechanical properties where the material properties emerge from both morphology and the material itself. An example is the development of nanoporous metallic materials for photonic and plasmonic applications which has recently attracted much interest. The general strategy is to take advantage of various size effects to introduce novel properties. These size effects arise from confinement of the material by pores and ligaments, and can range from electromagnetic resonances to length scale effects in plasticity. In this chapter we will focus on the mechanical properties of low density nanoporous metals and how these properties are affected by length scale effects and bonding characteristics. A thorough understanding of the mechanical behavior will open the door to further improve and fine-tune the mechanical properties of these sometimes very delicate materials, and thus will be crucial for integrating nanoporous metals into products. Cellular solids with pore sizes above 1 micron have been the subject of intense research for many years, and various scaling relations describing the mechanical properties have been developed.[4] In general, it has been found that the most important parameter in controlling their mechanical properties is the relative density, that is, the density of the foam divided by that of solid from which the foam is made. Other factors include the mechanical properties of the solid material and the foam morphology such as ligament shape and connectivity. The characteristic internal length scale of the structure as determined by pores and ligaments, on the other hand, usually has only little effect on the mechanical properties. This changes at the submicron length scale where the surface-to-volume ratio becomes large and the effect of free surfaces can no longer be neglected. As the material becomes more and more constraint by the presence of free surfaces, length scale effects on plasticity become more and more important and bulk properties can no longer be used to describe the material properties. Even the elastic properties may be affected as the reduced coordination of surface atoms and the concomitant redistribution of electrons may soften or stiffen the material. If, and to what extend, such length scale effects control the mechanical behavior of nanoporous materials depends strongly on the material and the characteristic length scale associated with its plastic deformation. For example, ductile materials such as metals which deform via dislocation-mediated processes can be expected to exhibit pronounced length scale effects in the sub-micron regime where free surfaces start to constrain efficient dislocation multiplication. In this chapter we will limit our discussion to our own area of expertise which is the mechanical behavior of nanoporous open-cell gold foams as a typical example of nanoporous metal foams. Throughout this chapter we will review our current understanding of the mechanical properties of nanoporous open-cell foams including both experimental and theoretical studies.

  4. Ultrasonic imaging system for in-process fabric defect detection

    DOE Patents [OSTI]

    Sheen, Shuh-Haw (Naperville, IL); Chien, Hual-Te (Naperville, IL); Lawrence, William P. (Downers Grove, IL); Raptis, Apostolos C. (Downers Grove, IL)

    1997-01-01T23:59:59.000Z

    An ultrasonic method and system are provided for monitoring a fabric to identify a defect. A plurality of ultrasonic transmitters generate ultrasonic waves relative to the fabric. An ultrasonic receiver means responsive to the generated ultrasonic waves from the transmitters receives ultrasonic waves coupled through the fabric and generates a signal. An integrated peak value of the generated signal is applied to a digital signal processor and is digitized. The digitized signal is processed to identify a defect in the fabric. The digitized signal processing includes a median value filtering step to filter out high frequency noise. Then a mean value and standard deviation of the median value filtered signal is calculated. The calculated mean value and standard deviation are compared with predetermined threshold values to identify a defect in the fabric.

  5. Reproductive/Social Behavior Undergraduate Honors Thesis

    E-Print Network [OSTI]

    Fernald, Russell

    Kelly Eaton Neural mechanisms of parental care and filial cannibalism in female fish 2010 Catherine Harrell Interactive behavior research with a virtual cichlid fish 2010 Hong-An Nguyen The role of excitatory synaptic inputs in the social regulation of preoptic area neurons in the cichlid fish

  6. Kibble-Zurek mechanism in colloidal monolayers

    E-Print Network [OSTI]

    Sven Deutschländer; Patrick Dillmann; Georg Maret; Peter Keim

    2015-03-30T23:59:59.000Z

    The Kibble-Zurek mechanism describes the evolution of topological defect structures like domain walls, strings, and monopoles when a system is driven through a second order phase transition. The model is used on very different scales like the Higgs field in the early universe or quantum fluids in condensed matter systems. A defect structure naturally arises during cooling if separated regions are too far apart to `communicate' (e.g. about their orientation or phase) due to finite signal velocity. This results in separated domains with different (degenerated) locally broken symmetry. Within this picture we investigate the non-equilibrium dynamics in a condensed matter analogue, a two-dimensional ensemble of colloidal particles. In equilibrium it obeys the so called Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) melting scenario with continuous (second-order like) phase transitions. The ensemble is exposed to a set of finite cooling rates covering roughly three orders of magnitude. Along this process, we analyze the defect and domain structure quantitatively via video microscopy and determine the scaling of the corresponding length scales as a function of the cooling rate. We indeed observe the scaling predicted by the Kibble-Zurek mechanism for the KTHNY universality class.

  7. I{sub DDQ} Testing and Defect Classes: A Tutorial

    SciTech Connect (OSTI)

    Soden, J.M. [Sandia National Labs., Albuquerque, NM (United States); Hawkins, C.F. [New Mexico State Univ., Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering

    1994-12-31T23:59:59.000Z

    I{sub DDQ} testing of CMOSICs is a technique for production quality and reliability improvement, design validation, and failure analysis. The origin and basic concepts of I{sub DDQ} testing are reviewed. The relationship of I{sub DDQ} testing to other test methods is considered in the context of the whole IC life cycle from design, fabrication, and test through end use. A comprehensive test strategy is described that uses defect classes based on defect electrical properties rather than traditional fault models.

  8. Multi-level scanning method for defect inspection

    DOE Patents [OSTI]

    Bokor, Jeffrey (Oakland, CA); Jeong, Seongtae (Richmond, CA)

    2002-01-01T23:59:59.000Z

    A method for performing scanned defect inspection of a collection of contiguous areas using a specified false-alarm-rate and capture-rate within an inspection system that has characteristic seek times between inspection locations. The multi-stage method involves setting an increased false-alarm-rate for a first stage of scanning, wherein subsequent stages of scanning inspect only the detected areas of probable defects at lowered values for the false-alarm-rate. For scanning inspection operations wherein the seek time and area uncertainty is favorable, the method can substantially increase inspection throughput.

  9. On the material geometry of continuously defective corrugated graphene sheets

    E-Print Network [OSTI]

    Andrzej Trzesowski

    2014-12-22T23:59:59.000Z

    Geometrical objects describing the material geometry of continuously defective graphene sheets are introduced and their compatibility conditions are formulated. Effective edge dislocations embedded in the Riemann-Cartan material space and defined by their scalar density and by local Burgers vectors, are considered. The case of secondary curvature-type defects created by this distribution of dislocations is analysed in terms of the material space. The variational geometry of the material space closely related with the existence of a characteristic length parameter is proposed. The formula which describes, in a reference temperature, the influence of dislocations on the material Riemannian metric, is given.

  10. On the defect induced gauge and Yukawa fields in graphene

    E-Print Network [OSTI]

    Corneliu Sochichiu

    2011-03-08T23:59:59.000Z

    We consider lattice deformations (both continuous and topological) in the hexagonal lattice Hubbard model in the tight binding approximation to graphene, involving operators with the range up to next-to-neighbor. In the low energy limit, we find that these deformations give rise to couplings of the electronic Dirac field to an external scalar (Yukawa) and gauge fields. The fields are expressed in terms of original defects. As a by-product we establish that the next-to-nearest order is the minimal range of deformations which produces the complete gauge and scalar fields. We consider an example of Stone--Wales defect, and find the associated gauge field.

  11. Thermodynamic and Kinetic Properties of Intrinsic Defects and Mg Transmutants in 3C-SiC Determined by Density Functional Theory

    SciTech Connect (OSTI)

    Hu, Shenyang Y.; Setyawan, Wahyu; Van Ginhoven, Renee M.; Jiang, Weilin; Henager, Charles H.; Kurtz, Richard J.

    2014-02-20T23:59:59.000Z

    Density functional theory (DFT) is used to calculate the thermodynamic and kinetic properties of transmutant Mg in 3C-SiC due to high-energy neutron irradiation associated with the fusion nuclear environment. The formation and binding energies of intrinsic defects, Mg-related defects, and clusters in 3C-SiC are systematically calculated. The minimum energy paths and activation energies during point defect migration and small cluster evolution are studied using a generalized solid-state elastic band (G-SSNEB) method with DFT energy calculations. Stable defect structures and possible defect migration mechanisms are identified. The evolution of binding energies during Mg2Si formation demonstrates that the formation of Mg2Si needs to overcome a critical nucleus size and nucleation barrier. It is also found that a compressive stress field exists around the Mg2Si nucleus. These data are important inputs in meso- and macro-scale modeling and experiments to understand and predict the impact of Mg on phase stability, microstructure evolution, and performance of SiC and SiC-based materials during long-term neutron exposures.

  12. Deformation Behavior of Laser Welds in High Temperature Oxidation Resistant Fe-Cr-Al Alloys for Fuel Cladding Applications

    SciTech Connect (OSTI)

    Field, Kevin G [ORNL; Gussev, Maxim N [ORNL; Yamamoto, Yukinori [ORNL; Snead, Lance Lewis [ORNL

    2014-01-01T23:59:59.000Z

    Ferritic-structured Fe-Cr-Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al in weight percent with a minor addition of yttrium using laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds has been carried out to determine the performance of welds as a function of alloy composition. Laser welding resulted in a defect free weld devoid of cracking or inclusions for all alloys studied. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. No significant correlation was found between the deformation behavior/mechanical performance of welds and the level of Cr or Al in the alloy ranges studied.

  13. Finite Deformation of Materials with an Ensemble of Defects

    SciTech Connect (OSTI)

    J.K. Dienes

    2003-01-01T23:59:59.000Z

    The theory of large deformations developed here is closely related to continuum mechanics but it differs in several major respects, especially in considering the deformation associated with various types of physical behavior, making it possible to synthesize a general approach to formulating constitutive laws. One goal is to derive general concepts of strain, strain rate, stress, and stress rate that are somewhat more physics-based than in most standard works on continuum mechanics, and to demonstrate some new relations between these quantities. With these concepts it is possible to develop a generalized principle of superposition of strain rates (GSSR) that accounts for damage as well as plastic flow. The traditional superposition of strain rates allows for addition of elastic and plastic strain rates and is commonly thought to be valid only for small strains. The GSSR allows us to compute deformations involving plastic flow and, in addition, brittle failure, fragmentation, high-pressure effects and other types of behavior as necessary, and the theory is valid for arbitrarily large deformations. In fact, GSSR is derived from more basic ideas and has broader application than the standard superposition of strain rates. The physical basis for calculations of complex material response is developed in a separate report. The implementation into the SCRAM computer program is documented separately. The polar decomposition theorem is taken as a starting point for the theory of large deformation, an approach somewhat different from that usually taken in continuum mechanics. Two sets of orthogonal axes are distinguished, space axes that are fixed in ambient space, and polar axes that are related to material deformation. This clarifies several concepts; for example, it is shown that the Signorini and Green-St. Venant strains are actually measures of the same physical entity, one in space axes and the other in polar axes. It follows that they are not competing measures, as is often implied in traditional continuum mechanics. It also follows that Piola stress is a measure in polar axes, while Cauchy stress is a measure in space axes. Another consequence of polar decomposition is a proof that vorticity is not a measure of the rate of material rotation (as is often stated in the hydrodynamics literature) but that they are related. This allows us to develop an exact approach to computing rates of tensor quantities, called polar rates, that account for material rotation in an exact way. This leads to a simple relation between Signorini strain rate and stretching (the symmetric part of the velocity gradient). It also follows that the polar stress rate is the appropriate measure for the rate of change of Cauchy stress, and that the more traditional stress rate of Zaremba, Jaumann, and Noll is only an approximation, valid at small strains. Examples are described for materials undergoing simple shear, vortex motion, and torsion.

  14. Computational mechanics

    SciTech Connect (OSTI)

    Goudreau, G.L.

    1993-03-01T23:59:59.000Z

    The Computational Mechanics thrust area sponsors research into the underlying solid, structural and fluid mechanics and heat transfer necessary for the development of state-of-the-art general purpose computational software. The scale of computational capability spans office workstations, departmental computer servers, and Cray-class supercomputers. The DYNA, NIKE, and TOPAZ codes have achieved world fame through our broad collaborators program, in addition to their strong support of on-going Lawrence Livermore National Laboratory (LLNL) programs. Several technology transfer initiatives have been based on these established codes, teaming LLNL analysts and researchers with counterparts in industry, extending code capability to specific industrial interests of casting, metalforming, and automobile crash dynamics. The next-generation solid/structural mechanics code, ParaDyn, is targeted toward massively parallel computers, which will extend performance from gigaflop to teraflop power. Our work for FY-92 is described in the following eight articles: (1) Solution Strategies: New Approaches for Strongly Nonlinear Quasistatic Problems Using DYNA3D; (2) Enhanced Enforcement of Mechanical Contact: The Method of Augmented Lagrangians; (3) ParaDyn: New Generation Solid/Structural Mechanics Codes for Massively Parallel Processors; (4) Composite Damage Modeling; (5) HYDRA: A Parallel/Vector Flow Solver for Three-Dimensional, Transient, Incompressible Viscous How; (6) Development and Testing of the TRIM3D Radiation Heat Transfer Code; (7) A Methodology for Calculating the Seismic Response of Critical Structures; and (8) Reinforced Concrete Damage Modeling.

  15. Dynamic Behavior and Microstructural Properties of Cancellous Bone.

    E-Print Network [OSTI]

    Boyer, Edmond

    A total of 15 distal parts of bovine femoral bones were used for this study (72 hours post mortemDynamic Behavior and Microstructural Properties of Cancellous Bone. S. Laporte1 , F. David1 , V of the cancellous bone and to identify the link between this mechanical behavior and the microstructural properties

  16. Self-Organization and Collective Behavior in Vertebrates

    E-Print Network [OSTI]

    Richner, Heinz

    , we consider systems in which insights from self-organization theory have been useful in improving our understanding of the underlying mechanics. Self-organization theory suggests that much of complex group behaviorSelf-Organization and Collective Behavior in Vertebrates Iain D. Couzin1 and Jens Krause2 1

  17. Mechanisms of articular cartilage defect repair in vivo after implantation of stratified cartilaginous tissue

    E-Print Network [OSTI]

    Chawla, Kanika

    2006-01-01T23:59:59.000Z

    diacetate, succinimidyl ester (CFDA, SE) which passivelysuccinimidyl ester (CFDA, SE) [33] which passively diffusesdiacetate, succinimidyl ester (CFDA, SE)[43] which passively

  18. Transport and Defect Mechanisms in Cuprous Delafossites. 1. Comparison of Hydrothermal and

    E-Print Network [OSTI]

    Poeppelmeier, Kenneth R.

    flat-panel displays, ultraviolet light emitting diodes, heterojunctions for solar cells, and all- oxide are utilized in a variety of commercial applications, such as flat-panel displays, photovoltaic devices

  19. Computational mechanics

    SciTech Connect (OSTI)

    Raboin, P J

    1998-01-01T23:59:59.000Z

    The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.

  20. Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

    SciTech Connect (OSTI)

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul G.; McKenzie, Bonnie B.; Bufford, Daniel Charles; Hall, Aaron Christopher.

    2014-09-01T23:59:59.000Z

    The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and significant plastic deformation during compressi on . On the other hand, the micron sized Al 2 O 3 particles exhibited brittle f racture in compression. In situ compression experiments showed 3um Al 2 O 3 particles fractured into pieces without observable plastic deformation in compression. Particle deformation behaviors will be used to inform Al 2 O 3 coating deposition parameters and particle - particle bonding in the consolidated Al 2 O 3 coatings.

  1. Native defects in tetradymite Bi2(TexSe3-x) topological insulators

    SciTech Connect (OSTI)

    Wang, Lin-Lin [Ames Laboratory; Huang, Mianliang [South Dakota School of Mines; Thimmaiah, Srinivasa [Ames Laboratory; Alam, Aftab [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; Kaminski, Adam [Ames Laboratory; Lograsso, Thomas A. [Ames Laboratory; Canfield, Paul [Ames Laboratory; Johnson, Duane D. [Ames Laboratory

    2013-03-08T23:59:59.000Z

    Formation energies of native defects in Bi2(TexSe3-x), with comparison to ideal Bi2Te2S, are calculated in density-functional theory to assess transport properties. Bi2Se3 is found to be n type for both Bi- and Se-rich growth conditions, while Bi2Te3 changes from n to p type going from Te- to Bi-rich conditions, as observed. Bi2Te2Se and Bi2Te2S are generally n type, explaining observed heavily doped n-type behavior in most samples. A (0/-) transition level at 16 meV above valence-band maximum for Bi on Te antisites in Bi2Te2Se is related to the observed thermally active transport gap causing a p-to-n transition at low temperature. Bi2(TexSe3-x) with x>2 are predicted to have high bulk resistivity due to effective carrier compensation when approaching the n-to-p crossover. Predicted behaviors are confirmed from characterization of our grown single crystals.

  2. Rate-dependent deformation behavior of poss-filled and plasticized poly(vinyl chloride)

    E-Print Network [OSTI]

    Soong, Sharon Yu-Wen

    2007-01-01T23:59:59.000Z

    Polymers are known to exhibit strong time-dependent mechanical behavior. In different temperatures or frequency regimes, the rate sensitivities of polymers change as various primary and secondary molecular mobility mechanisms ...

  3. Automatic Detection of Defects in Riveted Lapjoints using Eddy Current

    E-Print Network [OSTI]

    Automatic Detection of Defects in Riveted Lap­joints using Eddy Current Fredrik Lingvall Tadeusz originating from rivet holes in a riveted lap­joint using eddy current (EC) inspection is presented consisted of median filtering, rotation and de­biasing of the eddy current pattern. The rotation

  4. Nature of Radiation-Induced Defects in Quartz

    E-Print Network [OSTI]

    Bu Wang; Yingtian Yu; Isabella Pignatelli; Gaurav N. Sant; Mathieu Bauchy

    2015-04-10T23:59:59.000Z

    Although quartz ($\\rm \\alpha$-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage have not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics (MD) simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si--O connectivity defects, e.g., small Si--O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on $E^{\\prime}$ centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependence on the incident energy, of the amount of each type of the point defects formed, and quantify unambiguously the threshold displacement energies for both O and Si atoms. These results provide a comprehensive basis to assess the nature and extent of radiation damage in quartz.

  5. Preparation and characterization of low-defect surfaces

    SciTech Connect (OSTI)

    Robinson, T.O.

    1991-12-01T23:59:59.000Z

    Silver crystal surfaces with low defect densities were prepared electrochemically from aqueous solutions using capillary-growth techniques. These surfaces had low rates for the nucleation of new silver layers. The impedance of these inert silver/aqueous silver nitrate interfaces was used to determine silver adatom concentration and water dipole reorientation energetics.

  6. Nickel assisted healing of defective graphene S. Karoui,1

    E-Print Network [OSTI]

    Boyer, Edmond

    Nickel assisted healing of defective graphene S. Karoui,1 H. Amara,1 C. Bichara,2 and F. Ducastelle suggesting that their healing are thermally activated. We show that in presence of a nickel substrate we obtain a perfect graphene layer. The nickel-carbon chemical bonds keep breaking and reforming around

  7. Predicting Software Defects in Varying Development Lifecycles using Bayesian Nets

    E-Print Network [OSTI]

    Fenton, Norman

    Predicting Software Defects in Varying Development Lifecycles using Bayesian Nets Norman Fenton, this has required a custom- built BN for each software development lifecycle. We describe a more general BN software development lifecycle ­ to reflect both the differing number of testing stages in the lifecycle

  8. On the conservation of software defect CISM, University of Kingston

    E-Print Network [OSTI]

    Hatton, Les

    , T the temperature and R the gas constant is astonishingly accurate over a very wide range of pressures, then commonly used defect models for individual components directly im- ply that the distribution of component systems extremely accurately. For example, for a gas, PV = RT where P is the pressure, V the volume

  9. Spacetime Defects: von Kármán vortex street like configurations

    E-Print Network [OSTI]

    Patricio S. Letelier

    2001-07-05T23:59:59.000Z

    A special arrangement of spinning strings with dislocations similar to a von K\\'arm\\'an vortex street is studied. We numerically solve the geodesic equations for the special case of a test particle moving along twoinfinite rows of pure dislocations and also discuss the case of pure spinning defects.

  10. Atomic Computer Simulations of Defect Migration in 3C and 4H...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Computer Simulations of Defect Migration in 3C and 4H-SiC. Atomic Computer Simulations of Defect Migration in 3C and 4H-SiC. Abstract: Knowledge of the migration of intrinsic point...

  11. Characterization of Defects in N-type 4H-SiC After High-Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Characterization of Defects in N-type 4H-SiC After High-Energy N Ion Implantation by RBS-Channeling and Raman Spectroscopy. Characterization of Defects in N-type 4H-SiC After...

  12. First-principles study of defects and phase transition in UO2...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    defects and phase transition in UO2. First-principles study of defects and phase transition in UO2. Abstract: The electronic properties, structure and phase transformation of UO2...

  13. Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons

    E-Print Network [OSTI]

    Tongay, Sefaattin

    Point defects in semiconductors can trap free charge carriers and localize excitons. The interaction between these defects and charge carriers becomes stronger at reduced dimensionalities, and is expected to greatly influence ...

  14. Investigation of Microstructure and V-defect Formation in InxGa...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Microstructure and V-defect Formation in InxGa-xNGaN MQW Grown using Temperature-Gradient Metalorganic Investigation of Microstructure and V-defect Formation in InxGa-xNGaN MQW...

  15. Essays in behavioral economics

    E-Print Network [OSTI]

    Eil, David Holding

    2011-01-01T23:59:59.000Z

    Essays in Behavioral Economics A dissertation submitted inDoctor of Philosophy in Economics by David Holding Eilfunction,” The Review of Economics and Statistics, 1995,

  16. Interaction and Intelligent Behavior

    E-Print Network [OSTI]

    Mataric, Maja J.

    1994-08-01T23:59:59.000Z

    We introduce basic behaviors as primitives for control and learning in situated, embodied agents interacting in complex domains. We propose methods for selecting, formally specifying, algorithmically implementing, ...

  17. Hydrogen Sensing and Sensitivity of Palladium-Decorated Single-Walled Carbon Nanotubes with Defects

    E-Print Network [OSTI]

    Collins, Philip G

    2010-01-01T23:59:59.000Z

    pubs.acs.org/NanoLett Hydrogen Sensing and Sensitivity ofsite. KEYWORDS Carbon nanotube, hydrogen sensor, defect S

  18. EFFECTS OF MANUFACTURING DEFECTS ON THE STRENGTH OF TOUGHENED CARBON/EPOXY PREPREG COMPOSITES

    E-Print Network [OSTI]

    EFFECTS OF MANUFACTURING DEFECTS ON THE STRENGTH OF TOUGHENED CARBON/EPOXY PREPREG COMPOSITES .......................................................................................11 Toughened Resin Systems

  19. Equilibrium Defects and Concentrations in Nickel Aluminide Bin Bai* and Gary S. Collins

    E-Print Network [OSTI]

    Collins, Gary S.

    used in aerospace applications. Knowledge of its point defects is needed to understand phenomena by structural point defects: Ni-vacancies (VNi) in Ni-poor alloys and Ni-antisite atoms (NiAl) in Ni-rich alloys at temperatures up to 1300°C. Observation of VNi and NiAl structural defects in Ni-poor and Ni-rich alloys

  20. DISSERTATION THE EFFECT OF TRAPPING DEFECTS ON CIGS SOLAR-CELL

    E-Print Network [OSTI]

    Sites, James R.

    DISSERTATION THE EFFECT OF TRAPPING DEFECTS ON CIGS SOLAR-CELL PERFORMANCE Submitted by Pamela K ENTITLED THE EFFECT OF TRAPPING DEFECTS ON CIGS SOLAR-CELL PERFORMANCE BE ACCEPTED AS FULFILLING IN PART RE OF DISSERTATION THE EFFECT OF TRAPPING DEFECTS ON CIGS SOLAR-CELL PERFORMANCE The relationship between basic solar-cell

  1. AUTOMATIC DETECTION AND CLASSIFICATION OF DEFECT ON ROAD PAVEMENT USING ANISOTROPY MEASURE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    AUTOMATIC DETECTION AND CLASSIFICATION OF DEFECT ON ROAD PAVEMENT USING ANISOTROPY MEASURE Tien Sy-sy.nguyen@etu.univ-orleans.fr ABSTRACT Existing systems for automated pavement defect detection can only identify cracking type defects for the inspectors and road users [1]. In the last few years, several automated pavement inspecting systems which use

  2. Defects in Ge and Si caused by 1 MeV Si+ implantation*

    E-Print Network [OSTI]

    Florida, University of

    Defects in Ge and Si caused by 1 MeV Si+ implantation* D. P. Hickeya Department of Materials defect formation and evolution in the 001 Ge and Si wafers implanted with 1 MeV Si+ and 40 keV Si dissolve at the projected range for nonamorphizing implants into Si. However, in Ge, no 311 defect

  3. Effect of Niobium on the Defect Chemistry and Oxidation Kinetics of Tetragonal ZrO2

    E-Print Network [OSTI]

    Yildiz, Bilge

    Effect of Niobium on the Defect Chemistry and Oxidation Kinetics of Tetragonal ZrO2 Uuganbayar, Massachusetts 02139, United States ABSTRACT: Zirconium-niobium alloys are currently proposed for applications the effect of an extrinsic defect, niobium (Nb) dopant, on the defect equilibria and charge transfer

  4. Polarized Luminescence of Defects in CuGaSe2 Susanne Siebentritt1,2

    E-Print Network [OSTI]

    Rockett, Angus

    ). But for the whole group of I-III-VI2 chalcopyrite semiconductors no reliable identification of native defects by ESR been found in CuInSe2. [14] In the effort of relating the energy positions of the defects to defect. Res. Soc. Symp. Proc. Vol. 1012 © 2007 Materials Research Society 1012-Y13-01 #12;the experiment

  5. Oxygen sublattice defect in cobalt oxide : formation, migration, charge localization and thermodynamic processes

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    643 Oxygen sublattice defect in cobalt oxide : formation, migration, charge localization of oxygen defects in CoO using classical simulations. The charge localization in the oxygen vacancy has]. The defect concentration in the oxygen sublattice is several orders of magnitude smaller, but never- theless

  6. Defect production in tungsten: A comparison between field-ion microscopy and molecular-dynamics simulations

    E-Print Network [OSTI]

    Nordlund, Kai

    Defect production in tungsten: A comparison between field-ion microscopy and molecular defect production efficiencies obtained by FIM are a consequence of a surface effect, which greatly enhances defect production compared to that in the crystal interior. Comparison of clustering of vacancies

  7. Lung and alveolar wall elastic and hysteretic behavior in rats: effects of in vivo elastase treatment

    E-Print Network [OSTI]

    Lutchen, Kenneth

    Lung and alveolar wall elastic and hysteretic behavior in rats: effects of in vivo elastase P. Ingenito, and Be´la Suki. Lung and alveolar wall elastic and hysteretic behavior in rats: effects behavior of the alveolar walls and the macroscopic mechanical properties of the whole lung in an in vivo

  8. A new approach for the simultaneous tracking of multiple honeybees for analysis of hive behavior

    E-Print Network [OSTI]

    the most striking of animal behaviors, and the clarification of their mechanisms is a major subject behaviors, and the clarification of their mechanisms is a major subject in ethology (Manning and Dawkins: Monique Gauthier Apidologie (2011) 42:607­617 Original article * INRA, DIB-AGIB and Springer Science

  9. Defects in nematic membranes can buckle into pseudospheres

    E-Print Network [OSTI]

    John R. Frank; Mehran Kardar

    2007-10-31T23:59:59.000Z

    A nematic membrane is a sheet with embedded orientational order, which can occur in biological cells, liquid crystal films, manufactured materials, and other soft matter systems. By formulating the free energy of nematic films using tensor contractions from differential geometry, we elucidate the elastic terms allowed by symmetry, and indicate differences from hexatic membranes. We find that topological defects in the orientation field can cause the membrane to buckle over a size set by the competition between surface tension and in-plane elasticity. In the absence of bending rigidity the resulting shape is universal, known as a parabolic pseudosphere or a revolved tractrix. Bending costs oppose such buckling and modify the shape in a predictable manner. In particular, the anisotropic rigidities of nematic membranes lead to different shapes for aster and vortex defects, in principle enabling measurement of couplings specific to nematic membranes.

  10. Doping-assisted defect control in compound semiconductors

    SciTech Connect (OSTI)

    Specht, Petra; Weber, Eicke R.; Weatherford, Todd Russell

    2006-07-11T23:59:59.000Z

    The present invention relates to the production of thin film epilayers of III–V and other compounds with acceptor doping wherein the acceptor thermally stabilizes the epilayer, stabilize the naturally incorporated native defect population and therewith maintain the epilayer's beneficial properties upon annealing among other advantageous effects. In particular, balanced doping in which the acceptor concentration is similar to (but does not exceed) the antisite defects in the as-grown material is shown to be particularly advantageous in providing thermal stability, high resistivity and ultrashort trapping times. In particular, MBE growth of LT-GaAs epilayers with balanced Be doping is described in detail. The growth conditions greatly enhance the materials reproducibility (that is, the yield in processed devices). Such growth techniques can be transferred to other III–V materials if the growth conditions are accurately reproduced. Materials produced herein also demonstrate advantages in reproducibility, reliability and radiation hardening.

  11. Adsorption of self-avoiding walks at a defect

    E-Print Network [OSTI]

    Nicholas R. Beaton

    2014-09-01T23:59:59.000Z

    We consider the model of self-avoiding walks on the $d$-dimensional hypercubic lattice interacting with a $d^*$-dimensional defect, where $1\\leq d^*defect. When $d=3$ and $d^*=1$ or $2$, this can be seen as a model of long linear polymers in a good solvent, interacting with a linear filament or the interface of two liquids of different density. For all combinations of dimensions, there is a critical value $a_{\\rm c}$ which separates the desorbed and adsorbed phases of the model. We prove that in all cases $a_{\\rm c}=1$, confirming conjectures by a number of authors.

  12. Plasma-based localized defect for switchable coupling applications

    SciTech Connect (OSTI)

    Varault, Stefan [ONERA/DEMR, 2, Avenue Edouard Belin, BP4025, 31055 Toulouse Cedex (France); LAboratoire PLAsma et Conversion d'Energie (LAPLACE), UPS, CNRS, 118 Route de Narbonne, F-31062 Toulouse Cedex 9 (France); Gabard, Benjamin [STAE, 4, rue Emile Monso, BP84234, 31030 Toulouse, Cedex 4 (France); Sokoloff, Jerome [LAboratoire PLAsma et Conversion d'Energie (LAPLACE), UPS, CNRS, 118 Route de Narbonne, F-31062 Toulouse Cedex 9 (France); Bolioli, Sylvain [ONERA/DEMR, 2, Avenue Edouard Belin, BP4025, 31055 Toulouse Cedex (France)

    2011-03-28T23:59:59.000Z

    We report in this paper experimental measurements in order to validate the concept of switchable electromagnetic band gap filters based on plasma capillaries in the microwave regime. The plasma tube is embedded inside the structure to create a bistable (plasma on or off) punctual defect. We first investigate two kinds of discharge tubes: Ar-Hg and pure Ne, which we then use to experimentally achieve plasma-based reconfigurable applications, namely, a two-port coupler and a two-port demultiplexer.

  13. Ab initio studies of niobium defects in uranium

    SciTech Connect (OSTI)

    Xiang, S; Huang, H; Hsiung, L

    2007-06-01T23:59:59.000Z

    Uranium (U), with the addition of small amount of niobium (Nb), is stainless. The Nb is fully miscible with the high temperature phase of U and tends to segregate upon cooling below 647 C. The starting point of segregation is the configuration of Nb substitutional or interstitial defects. Using density-functional-theory based ab initio calculations, the authors find that the formation energy of a single vacancy is 1.08 eV, that of Nb substitution is 0.59 eV, that of Nb interstitial at octahedral site is 1.58 eV, and that of Nb interstitial at tetrahedral site is 2.35 eV; all with reference to a reservoir of {gamma} phase U and pure Nb. The formation energy of Nb defects correlates with the local perturbation of electron distribution; higher formation energy to larger perturbation. Based on this study, Nb atoms thermodynamically prefer to occupy substitutional sites in {gamma} phase U, and they prefer to be in individual substitutional defects than clusters.

  14. Light defection due to a charged, rotating body

    E-Print Network [OSTI]

    Sarani Chakraborty; A. K. Sen

    2014-06-05T23:59:59.000Z

    According to GTR and subsequent developments in the field, it is known that there are three factors namely mass, rotation and charge that can influence the space-time geometry. Accordingly, we discuss the effect of space-time geometry of a charged, rotating body on the motion of the light ray. We obtained the expression for equatorial defection of light due to such a body up to fourth order term. In our expression for defection angle it is clear that charge can influence the path of light ray. We used the null geodesic approach of light ray for our calculation. If we set the charge to zero our expression of bending angle gets reduced to the Kerr equatorial bending angle.If we set rotation to zero our expression reduces to Resinner-Nordstr$\\ddot{o}$m defection angle and if we set both charge and rotation to zero our expression reduces to Schwarzschild bending angle. However, we get non-zero bending angle for a hypothetical massless, rotating, charged body.

  15. Nature of Radiation-Induced Defects in Quartz

    E-Print Network [OSTI]

    Wang, Bu; Pignatelli, Isabella; Sant, Gaurav N; Bauchy, Mathieu

    2015-01-01T23:59:59.000Z

    Although quartz ($\\rm \\alpha$-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage have not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics (MD) simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si--O connectivity defects, e.g., small Si--O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on $E^{\\prime}$ centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependenc...

  16. Effect of friction stir weld defects on fatigue lifetime of an Al-Cu-Li alloy T. Le Jolu, T.F. Morgeneyer, A.F. Gourgues-Lorenzon

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Effect of friction stir weld defects on fatigue lifetime of an Al-Cu-Li alloy (AA-2198) T. Le of friction stir welds of a 2198 Al-alloy in T851 condition has been assessed experimentally by investigating concerning crack initiation mechanisms. KEYWORDS Friction Stir Welding, Joint Line Remnant, Al-Cu-Li, S

  17. Method for characterizing mask defects using image reconstruction from X-ray diffraction patterns

    DOE Patents [OSTI]

    Hau-Riege, Stefan Peter (Fremont, CA)

    2007-05-01T23:59:59.000Z

    The invention applies techniques for image reconstruction from X-ray diffraction patterns on the three-dimensional imaging of defects in EUVL multilayer films. The reconstructed image gives information about the out-of-plane position and the diffraction strength of the defect. The positional information can be used to select the correct defect repair technique. This invention enables the fabrication of defect-free (since repaired) X-ray Mo--Si multilayer mirrors. Repairing Mo--Si multilayer-film defects on mask blanks is a key for the commercial success of EUVL. It is known that particles are added to the Mo--Si multilayer film during the fabrication process. There is a large effort to reduce this contamination, but results are not sufficient, and defects continue to be a major mask yield limiter. All suggested repair strategies need to know the out-of-plane position of the defects in the multilayer.

  18. Behavioral/Systems/Cognitive Potential Network Mechanisms Mediating

    E-Print Network [OSTI]

    Kopell, Nancy

    , Boston, Massachusetts 02215, 2Department of Anesthesia and Critical Care, Massachusetts General Hospital with general anesthesia. Key words: propofol anesthesia; paradoxical excitation; GABAA ; M-current; EEG; beta rhythms Introduction General anesthesia is defined as a reversible, drug-induced con- junction of four

  19. Behavioral mechanisms underlying the extinction of cocaine self-administration

    E-Print Network [OSTI]

    Valles, Rodrigo, Jr.

    2006-04-12T23:59:59.000Z

    The aim of the present series of experiments was to outline the influence of different doses of cocaine during training, training schedule, training length and abstinence duration to modulate subsequent extinction and reinstatement patterns. Abram...

  20. Neurotoxic mechanisms of methylmercury: cellular and behavior changes

    E-Print Network [OSTI]

    Bellum, Sairam

    2007-04-25T23:59:59.000Z

    The organic or methylated form of mercury (Hg), consisting of one methyl group bound to each atom of Hg, (methylmercury; MeHg), accounts for most of the Hg to which humans are exposed. MeHg, by virtue of its lipophilicity is highly neurotoxic...

  1. Cartel Mechanism Design: Nonratifiable Conditions of Collusive Behavior

    E-Print Network [OSTI]

    Hsueh, Shao-Chieh

    2012-02-14T23:59:59.000Z

    boost exemption or have more budget to subsidize agents, it is less likely that a ring will be formed. v To my family and Hellen vi ACKNOWLEDGMENTS First, I am heartily grateful to my advisory committee. Professor Guoqiang Tian, chair of my advisory....3 concludes. All proofs are in Appendix A. 2.2. Model There are one seller and n (n ? 2) bidders in the economy. Bidder i?s value is vi ? V , i = (1, ..., n), which represents i?s willingness to pay for an object in an auction, and v = (v1, ..., vn...

  2. Thermo-mechanical Behavior of Lithium-ion Battery Electrodes 

    E-Print Network [OSTI]

    An, Kai

    2013-11-25T23:59:59.000Z

    Developing electric vehicles is widely considered as a direct approach to resolve the energy and environmental challenges faced by the human race. As one of the most promising power solutions to electric cars, the lithium ion battery is expected...

  3. Roles of nanofiller structure on mechanical behavior of thermoplastic nanocomposites 

    E-Print Network [OSTI]

    Weon, Jong Il

    2006-10-30T23:59:59.000Z

    Traitedness has been described as the �the degree to which a particular trait structure is approximated in a given person� (Tellegen, p. 28, 1991) and has been hypothesized as one explanation for findings of weak trait...

  4. ``Modeling the Dynamic Mechanical Behavior of Elastomers'' H. T. Banks

    E-Print Network [OSTI]

    in a nontrivial manner. Additionally, many elastomers, particularly those with a synthetic rubber base, exhibit 405 Gregson Drive Cary, NC 27511 Presented at a meeting of the Rubber Division, American Chemical (hysteresis). Currently available software packages for studying the stress­strain laws in rubber

  5. Mechanical Behavior of Cryomilled Ni Superalloy by Spark Plasma Sintering

    E-Print Network [OSTI]

    2009-01-01T23:59:59.000Z

    Ni Superalloy by Spark Plasma Sintering Z. ZHANG, B.Q. HAN,cryomilling and spark plasma sintering (SPS) was studied.prepared by the spark plasma sintering (SPS) technique. To

  6. Characterization of Thermo-Mechanical Behaviors of Advanced High...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Forming Integrated Forming Induced Phase Transformation in TRIP Steel Side Induced Phase Transformation in TRIP Steel Side Rail Crash Simulations Rail Crash Simulations (a)...

  7. Optical and mechanical behavior of the optical fiber infrasound sensor

    E-Print Network [OSTI]

    DeWolf, Scott

    2009-01-01T23:59:59.000Z

    1.2 The Optical Fiber Infrasound Sensor . . . . . . .Fiber Infrasound Sensor Optical fibers are well known forSchnidrig. An optical fiber infrasound sensor: A new lower

  8. Behavioral/Systems/Cognitive Gain Mechanisms for Contextually Guided

    E-Print Network [OSTI]

    Andersen, Richard

    . Two recent theoretical studies ad- dressed contextual visuomotor remapping. Salinas (Salinas, 2004

  9. Comments on: 2015 VIII MECHANICAL BEHAVIOR OF SALT

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i tCollaboration MarchCanadian2016Department

  10. Characterization of Thermo-Mechanical Behaviors of Advanced High Strength

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof EnergyAdministration-DesertofSuccess Stories from

  11. Characterization of Thermo-Mechanical Behaviors of Advanced High Strength

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof EnergyAdministration-DesertofSuccess Stories fromSteels (AHSS) |

  12. Mechanical and microstructural response of Ni sub 3 Al at high strain rate and elevated temperatures

    SciTech Connect (OSTI)

    Sizek, H.W.; Gray, G.T. III.

    1990-01-01T23:59:59.000Z

    In this paper, the effect of strain rate and temperature on the substructure evolution and mechanical response of Ni{sub 3}Al will be presented. The strain rate response of Ni{sub 3}Al was studied at strain rates from 10{sup {minus}3} s{sup {minus}1} (quasi-static) to 10{sup 4} s{sup {minus}1} using a Split Hopkinson Pressure Bar. The Hopkinson Bar tests were conducted at temperatures ranging from 77K to 1273K. At high strain rates the flow strength increased significantly with increasing temperature, similar to the behavior observed at quasi-static rates. The work hardening rates increased with strain rate and varied with temperatures. The work hardening rates, appeared to be significantly higher than those found for Ni270. The substructure evolution was characterized utilizing TEM. The defect generation and rate sensitivity of Ni{sub 3}Al are also discussed as a function of strain rate and temperature. 15 refs., 4 figs.

  13. Defect Structure of Epitaxial CrxV1 ? x Thin Films on MgO(001)

    SciTech Connect (OSTI)

    Kaspar, Tiffany C.; Bowden, Mark E.; Wang, Chong M.; Shutthanandan, V.; Manandhar, Sandeep; Van Ginhoven, Renee M.; Wirth, Brian D.; Kurtz, Richard J.

    2014-01-01T23:59:59.000Z

    Epitaxial thin films of CrxV1-x over the entire composition range were deposited on MgO(001) by molecular beam epitaxy. The films exhibited the expected 45° in-plane rotation with no evidence of phase segregation or spinodal decomposition. Pure Cr, with the largest lattice mismatch to MgO, exhibited full relaxation and cubic lattice parameters. As the lattice mismatch decreased with alloy composition, residual epitaxial strain was observed. For 0.2 ? x ? 0.4 the films were coherently strained to the substrate with associated tetragonal distortion; near the lattice-matched composition of x = 0.33, the films exhibited strain-free pseudomorphic matching to MgO. Unusually, films on the Cr-rich side of the lattice-matched composition exhibited more in-plane compression than expected from the bulk lattice parameters; this result was confirmed with both x-ray diffraction and Rutherford backscattering spectrometry channeling measurements. Although thermal expansion mismatch in the heterostructure may play a role, the dominant mechanism for this phenomenon is still unknown. High resolution transmission electron microscopy was utilized to characterize the misfit dislocation network present at the film/MgO interface. Dislocations were found to be present with a non-uniform distribution, which is attributed to the Volmer-Weber growth mode of the films. The CrxV1-x / MgO(001) system can serve as a model system to study both the fundamentals of defect formation in bcc films and the interplay between nanoscale defects such as dislocations and radiation damage.

  14. Essays in Behavioral Finance

    E-Print Network [OSTI]

    Huang, Xing

    2013-01-01T23:59:59.000Z

    behavior. Journal of Finance 64(6), 2515–2534. Cohen, L. ,returns. Journal of Finance 63(4), 1977–2011. Cohen, L. andannouncements. Journal of Finance 64, 709–749. DeLong, J.

  15. Aquifer behavior with reinjection 

    E-Print Network [OSTI]

    Bonet, Euclides Jose

    1967-01-01T23:59:59.000Z

    AQUIFER BEHAVIOR WITH REINJECTION A Thesis By EUCLIDES JOSE BONET Submitted to the Graduate College of the Texas ARUM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May, f967 Major Subject... Petroleum Engineering AQUIFER BEHAVIOR WITH REINJECTION A Thesis By E UC LI DES JOSE BONE T Approved as to style and content by: (Chairman of Committee) (Member) (Member) May, 1967 ACKNOWLEDGMENT Thanks are due to Petroleo Brasilerio S...

  16. In Situ Small Scale Mechanical Characterization of Materials Under Environmental 

    E-Print Network [OSTI]

    Sanders, Matthew Wayne

    2011-10-21T23:59:59.000Z

    , aluminum and titanium alloys were examined using those two techniques. Analysis of their behavior in comparison with their published mechanical properties made it possible to establish connections between test parameters and conventional uniaxial tensile...

  17. Mechanics of deformation of carbon nanotube-polymer nanocomposites

    E-Print Network [OSTI]

    Akiskalos, Theodoros, 1978-

    2004-01-01T23:59:59.000Z

    The goal is to develop finite element techniques to evaluate the mechanical behavior of carbon nanotube enabled composites and gain a thorough understanding of the parameters that affect the properties of the composite, ...

  18. Prediction of failure behavior of a welded pressure vessel containing flaws during a hydrogen-charged burst test

    SciTech Connect (OSTI)

    Bhuyan, G.S. [Powertech Labs. Inc., Surrey, British Columbia (Canada); Sperling, E.J. [Amoco Corp., Naperville, IL (United States); Shen, G. [CANMET, Ottawa, Ontario (Canada). Metals Technology Labs.; Yin, H. [Mobil Research and Development Corp., Farmers Branch, TX (United States); Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States)

    1996-12-01T23:59:59.000Z

    An industry-government collaborative program was carried out with an aim to promoting the acceptance of fracture mechanics based fitness-for-service assessment methodology for a service-damaged pressure vessel. A collaborative round robin exercise was carried out to predict the fracture behavior of a vessel containing hydrogen damage, fabrication related lack-of-fusion defects, an artificially induced fatigue crack and a localized thinned area. The fracture assessment procedures used include the US ASME Material Property Council`s PREFIS Program based on the British Standard (BS) Published Document (PD) 6493, ASME Section XI and The Central Electricity Generating Board (CEGB) R6 approach; The welding Institute (TWI) CRACKWISE program (based on BS PD6493 Level 2 approach), a variant of the R6 approach, J-tearing instability approaches, various J-estimation schemes, LEFM approach and simplified stress analysis. Assessments were compared with the results obtained from a hydrogen charged burst test of the vessel. Predictions, based on the J-tearing approach, compared well with the actual burst test results. Actual burst pressure was about five times the operating pressure.

  19. Prediction of failure behavior of a welded pressure vessel containing flaws during a hydrogen-charged burst test

    SciTech Connect (OSTI)

    Bhuyan, G.S. [Powertech Labs Inc., Surrey, British Columbia (Canada); Sperling, E.J. [BP-Amoco, Calgary, Alberta (Canada); Shen, G. [CANMET, Ottawa, Ontario (Canada). Metals Technology Labs.; Yin, H. [Mobil Technology Co., Dallas, TX (United States); Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States)

    1999-08-01T23:59:59.000Z

    An industry-government collaborative program was carried out with an aim to promoting the acceptance of fracture mechanics-based fitness-for-service assessment methodology for a service-damaged pressure vessel. A collaborative round robin exercise was carried out to predict the fracture behavior of a vessel containing hydrogen damage, fabrication-related lack-of-fusion defects, an artificially induced fatigue crack, and a localized thinned area. The fracture assessment procedures used include the US ASME Material Property Council`s PREFIS Program based on the British Standard (BS) Published Document (PD) 6493, ASME Section XI and The Central Electricity Generating Board (CEGB) R6 approach, The Welding Institute (TWI) CRACKWISE program (based on BS PD6493 Level 2 approach), a variant of the R6 approach, J-tearing instability approaches, various J-estimation schemes, LEFM approach, and simplified stress analysis. Assessments were compared with the results obtained from a hydrogen-charged burst test of the vessel. Predictions, based on the J-tearing approach, compared well with the actual burst test results. Actual burst pressure was about five times the operating pressure.

  20. Modeling and implementation of solder-activated joints for single actuator, centimeter-scale robotic mechanisms

    E-Print Network [OSTI]

    Telleria, Maria J

    2010-01-01T23:59:59.000Z

    This thesis explains when, and why, solder-based phase change materials (PCMs) are best-suited as a means to modify a robotic mechanism's kinematic and elastomechanic behavior. The preceding refers to mechanisms that possess ...

  1. Blade reliability collaborative : collection of defect, damage and repair data.

    SciTech Connect (OSTI)

    Ashwill, Thomas D.; Ogilvie, Alistair B.; Paquette, Joshua A.

    2013-04-01T23:59:59.000Z

    The Blade Reliability Collaborative (BRC) was started by the Wind Energy Technologies Department of Sandia National Laboratories and DOE in 2010 with the goal of gaining insight into planned and unplanned O&M issues associated with wind turbine blades. A significant part of BRC is the Blade Defect, Damage and Repair Survey task, which will gather data from blade manufacturers, service companies, operators and prior studies to determine details about the largest sources of blade unreliability. This report summarizes the initial findings from this work.

  2. Preshot Predictions for Defect Induced Mix (DIME) Capsules

    SciTech Connect (OSTI)

    Bradley, Paul A. [Los Alamos National Laboratory; Krasheninnikova, Natalia S. [Los Alamos National Laboratory; Tregillis, Ian L. [Los Alamos National Laboratory; Schmitt, Mark J. [Los Alamos National Laboratory

    2012-07-31T23:59:59.000Z

    In this memo, we evaluate the most probable yield and other results for the Defect Induced Mix (DIME-12A) Polar Direct Drive (PDD) capsule-only shots. We evaluate the expected yield, bang time, burn averaged ion temperature, and the average electron temperature of the Ge line-emitting region. We also include synthetic images of the capsule backlit by Cu K-{alpha} emission (8.39 keV) and core self-emission synthetic images. This memo is a companion to the maximum credible yield memo (LA-UR-12-00287) published earlier.

  3. Thermal imaging analysis of material structures and defects.

    SciTech Connect (OSTI)

    Sun, J. G.; Nuclear Engineering Division

    2008-01-01T23:59:59.000Z

    A numerical one-dimensional (1D) heat-transfer model was developed to simulate the surface temperature response under one-sided pulsed thermal imaging for plate samples with internal material variations including different optical and thermal properties, multilayer structures, and defect distributions (delaminations). The simulation results showed the complexity and subtle differences of the thermal imaging response to the material variations. With further development in data processing technologies, it is expected that thermal imaging may be used to detect and predict these material property variations.

  4. Sandia Energy - Research Challenge 4: Defect-Carrier Interactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > TheNuclear PressLaboratory FellowsPolariton4: Defect-Carrier

  5. MECHANICS AND NONLINEAR CONTROL: MAKING UNDERWATER VEHICLES

    E-Print Network [OSTI]

    Leonard, Naomi

    which pro­ vide powerful means to understand and describe mechanical system behavior. Methods incorporat performance and efficient use of on­board power. We highlight the underwater vehicle control sys­ tem both torques that mimic the stabilizing moment associated with gravitational and buoy­ ant forces, using

  6. Helium Migration Mechanisms in Polycrystalline Uranium Dioxide

    SciTech Connect (OSTI)

    Martin, Guillaume; Desgardin, Pierre; Sauvage, Thierry; Barthe, Marie-France [CERI, CNRS, 3 A rue de la Ferollerie, ORLEANS, 45071 (France); Garcia, Philippe; Carlot, Gaelle [DEN/DEC/SESC/LLCC, CEA Cadarache, Saint Paul Lez Durance, 13108 (France)

    2007-07-01T23:59:59.000Z

    This study aims at identifying the release mechanisms of helium in uranium dioxide. Two sets of polycrystalline UO{sub 2} sintered samples presenting different microstructures were implanted with {sup 3}He ions at concentrations in the region of 0.1 at.%. Changes in helium concentrations were monitored using two Nuclear Reaction Analysis (NRA) techniques based on the {sup 3}He(d,{alpha}){sup 1}H reaction. {sup 3}He release is measured in-situ during sample annealing at temperatures ranging between 700 deg. C and 1000 deg. C. Accurate helium depth profiles are generated after each annealing stage. Results that provide data for further understanding helium release mechanisms are discussed. It is found that helium diffusion appears to be enhanced above 900 deg. C in the vicinity of grain boundaries possibly as a result of the presence of defects. (authors)

  7. Identification of dominant scattering mechanism in epitaxial graphene on SiC

    SciTech Connect (OSTI)

    Lin, Jingjing; Guo, Liwei, E-mail: lwguo@iphy.ac.cn, E-mail: chenx29@aphy.iphy.ac.cn; Jia, Yuping; Huang, Jiao; Guo, Yu; Li, Zhilin; Chen, Xiaolong, E-mail: lwguo@iphy.ac.cn, E-mail: chenx29@aphy.iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Yang, Rong; Wu, Shuang; Zhang, Guangyu [Nanoscale Physics and Devices Laboratory, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China)

    2014-05-05T23:59:59.000Z

    A scheme of identification of scattering mechanisms in epitaxial graphene (EG) on SiC substrate is developed and applied to three EG samples grown on SiC (0001), (112{sup Ż}0), and (101{sup Ż}0) substrates. Hall measurements combined with defect detection technique enable us to evaluate the individual contributions to the carrier scatterings by defects and by substrates. It is found that the dominant scatterings can be due to either substrate or defects, dependent on the substrate orientations. The EG on SiC (112{sup Ż}0) exhibits a better control over the two major scattering mechanisms and achieves the highest mobility even with a high carrier concentration, promising for high performance graphene-based electronic devices. The method developed here will shed light on major aspects in governing carrier transport in EG to harness it effectively.

  8. Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

    SciTech Connect (OSTI)

    Qingbang, Han; Ling, Chen; Changping, Zhu [Changzhou Key Laboratory of Sensor Networks and Environmental Sensing, College of IOT, Hohai University Changzhou, Jiangsu, 213022 (China)

    2014-02-18T23:59:59.000Z

    The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

  9. Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network

    SciTech Connect (OSTI)

    Gabe V. Garcia

    2005-01-03T23:59:59.000Z

    A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates.

  10. Spatial correlation between chemical and topological defects in vitreous silica: UV-resonance Raman study

    SciTech Connect (OSTI)

    Saito, M., E-mail: makina.saito@elettra.eu; D’Amico, F.; Bencivenga, F.; Cucini, R.; Gessini, A.; Principi, E.; Masciovecchio, C. [Elettra-Sincrotrone Trieste, S. S. 14 Km 163.5, I-34149 Trieste (Italy)

    2014-06-28T23:59:59.000Z

    A spatial correlation between chemical and topological defects in the tetrahedron network in vitreous silica produced by a fusion process of natural quartz crystals was found by synchrotron-based UV resonance Raman experiments. Furthermore, a quantitative correlation between these defects was obtained by comparing visible Raman and UV absorption spectra. These results indicate that in vitreous silica produced by the fusion process the topological defects disturb the surrounding tetrahedral silica network and induce further disorder regions with sub nanometric sizes.

  11. Multiple stalk formation as a pathway of defect-induced membrane fusion

    E-Print Network [OSTI]

    D. B. Lukatsky; Daan Frenkel

    2004-03-29T23:59:59.000Z

    We propose that the first stage of membrane fusion need not be the formation of a single stalk. Instead, we consider a scenario for defect-induced membrane fusion that proceeds cooperatively via multiple stalk formation. The defects (stalks or pores) attract each other via membrane-mediated capillary interactions that result in a condensation transition of the defects. The resulting dense phase of stalks corresponds to the so-called fusion intermediate.

  12. Mechanics and tribology of MEMS materials.

    SciTech Connect (OSTI)

    Prasad, Somuri V.; Dugger, Michael Thomas; Boyce, Brad Lee; Buchheit, Thomas Edward

    2004-04-01T23:59:59.000Z

    Micromachines have the potential to significantly impact future weapon component designs as well as other defense, industrial, and consumer product applications. For both electroplated (LIGA) and surface micromachined (SMM) structural elements, the influence of processing on structure, and the resultant effects on material properties are not well understood. The behavior of dynamic interfaces in present as-fabricated microsystem materials is inadequate for most applications and the fundamental relationships between processing conditions and tribological behavior in these systems are not clearly defined. We intend to develop a basic understanding of deformation, fracture, and surface interactions responsible for friction and wear of microelectromechanical system (MEMS) materials. This will enable needed design flexibility for these devices, as well as strengthen our understanding of material behavior at the nanoscale. The goal of this project is to develop new capabilities for sub-microscale mechanical and tribological measurements, and to exercise these capabilities to investigate material behavior at this size scale.

  13. Subsurface Defect Detection in Metals with Pulsed Eddy Current

    SciTech Connect (OSTI)

    Plotnikov, Yuri A. [GE Global Research Center, One Research Circle, Niskayuna, NY 12309-1135 (United States); Bantz, Walter J. [GE Aircraft Engines M and QTD, 10270 St. Rita Lane, Cincinnati, OH 45215 (United States)

    2005-04-09T23:59:59.000Z

    The eddy current (EC) method is traditionally used for open surface crack detection in metallic components. Subsurface voids in bulk metals can also be detected by the eddy current devices. Taking into consideration the skin effect in conductive materials, a lower frequency of electromagnetic excitation is used for a deeper penetration. A set of special specimens was designed and fabricated to investigate sensitivity to subsurface voids. Typically, flat bottom holes (FBHs) are used for subsurface defect simulation. This approach is not very representative of real defects for eddy current inspection because the FBH depth extends to the bottom of the specimen. Two-layer specimens with finite depth FBHs were fabricated and scanned with conventional EC of variable frequency. Sensitivity and spatial resolution of EC diminish with flaw depth. The pulsed EC approach was applied for flaw detection at variable distance under the surface. The transient response from multi-layer model was derived and compared to experiments. The multi-frequency nature of pulsed excitation provides effective coverage of a thick layer of material in one pass. Challenging aspects of subsurface flaw detection and visualization using the EC technique are discussed.

  14. Nematic ordering of topological defects in active liquid crystals

    E-Print Network [OSTI]

    Anand U. Oza; Jörn Dunkel

    2015-07-15T23:59:59.000Z

    Identifying the ordering principles of intracellular matter is key to understanding the physics of microbiological systems. Recent experiments show that ATP-driven microtubule-kinesin bundles can form non-equilibrium networks of liquid-crystalline order when trapped in an oil-water interface near a solid boundary. At high densities, the bundles realize a 2D active nematic phase characterized by spontaneous creation and annihilation of topological defects, reminiscent of particle-pair production processes in quantum systems. This remarkable discovery sparked considerable theoretical interest, yet a satisfactory mathematical description has remained elusive, primarily for the following two reasons. First, prevailing multi-component theories feature a large number of unknown parameters that make quantitative comparison with experiment infeasible. Second, the currently favored hydrodynamic models assume divergence-free 2D interfacial flow, thereby promoting turbulent pattern formation through upward cascades. Such cascades are unlikely to occur in experiments, where interface and bulk fluid can continuously exchange matter. Here, we propose a compact alternative continuum theory for dense active liquid crystals by merging ideas from the Landau-de Gennes and Swift-Hohenberg theories. The resulting fourth-order model agrees quantitatively with experimental data, correctly predicts a regime of long-range nematic alignment of defects, and manifests an analogy with a generalized Gross-Pitaevskii quantum theory. Generally, our results suggest that universal ordering principles may govern a wide range of active materials.

  15. Defect Prevention and Detection in Software for Automated Test Equipment

    SciTech Connect (OSTI)

    E. Bean

    2006-11-30T23:59:59.000Z

    Software for automated test equipment can be tedious and monotonous making it just as error-prone as other software. Active defect prevention and detection are also important for test applications. Incomplete or unclear requirements, a cryptic syntax used for some test applications—especially script-based test sets, variability in syntax or structure, and changing requirements are among the problems encountered in one tester. Such problems are common to all software but can be particularly problematic in test equipment software intended to test another product. Each of these issues increases the probability of error injection during test application development. This report describes a test application development tool designed to address these issues and others for a particular piece of test equipment. By addressing these problems in the development environment, the tool has powerful built-in defect prevention and detection capabilities. Regular expressions are widely used in the development tool as a means of formally defining test equipment requirements for the test application and verifying conformance to those requirements. A novel means of using regular expressions to perform range checking was developed. A reduction in rework and increased productivity are the results. These capabilities are described along with lessons learned and their applicability to other test equipment software. The test application development tool, or “application builder”, is known as the PT3800 AM Creation, Revision and Archiving Tool (PACRAT).

  16. New mechanism of membrane fusion

    E-Print Network [OSTI]

    M. Mueller; K. Katsov; M. Schick

    2001-10-10T23:59:59.000Z

    We have carried out Monte Carlo simulation of the fusion of bilayers of single chain amphiphiles which show phase behavior similar to that of biological lipids. The fusion mechanism we observe is very different from the ``stalk'' hypothesis. Stalks do form on the first stage of fusion, but they do not grow radially to form a hemifused state. Instead, stalk formation destabilizes the membranes and results in hole formation in the vicinity of the stalks. When holes in each bilayer nucleate spontaneously next to the same stalk, an incomplete fusion pore is formed. The fusion process is completed by propagation of the initial connection, the stalk, along the edges of the aligned holes.

  17. Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN

    SciTech Connect (OSTI)

    Volnianska, O.; Zakrzewski, T. [Institute of Physics PAS, 02-668 Warsaw (Poland); Boguslawski, P. [Institute of Physics PAS, 02-668 Warsaw (Poland); Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz (Poland)

    2014-09-21T23:59:59.000Z

    Electronic structure of the Mn and Fe ions and of the gallium vacancy V{sub Ga} in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ? 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of V{sub Ga}, these effects lead to stabilization of spin polarization and the “negative-U{sub eff}” behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ? U(Mn) ? 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn)

  18. 2012 DEFECTS IN SEMICONDUCTORS GORDON RESEARCH CONFERENCE, AUGUST 12-17, 2012

    SciTech Connect (OSTI)

    GLASER, EVAN

    2012-08-17T23:59:59.000Z

    The meeting shall strive to develop and further the fundamental understanding of defects and their roles in the structural, electronic, optical, and magnetic properties of bulk, thin film, and nanoscale semiconductors and device structures. Point and extended defects will be addressed in a broad range of electronic materials of particular current interest, including wide bandgap semiconductors, metal-oxides, carbon-based semiconductors (e.g., diamond, graphene, etc.), organic semiconductors, photovoltaic/solar cell materials, and others of similar interest. This interest includes novel defect detection/imaging techniques and advanced defect computational methods.

  19. HIGH QUALITY InGaN FOR PHOTOVOLTAIC APPLICATIONS: TYPE AND SPATIAL DISTRIBUTION OF CRYSTALLINE DEFECTS

    E-Print Network [OSTI]

    Honsberg, Christiana

    of defects act as recombination channels and lower the short-circuit current, as well as tend to pin the open-circuit

  20. Interstitial defects in silicon from 1{endash}5 keV Si{sup +} ion implantation

    SciTech Connect (OSTI)

    Agarwal, A.; Haynes, T.E. [Oak Ridge National Laboratory, MS-6048, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, MS-6048, Oak Ridge, Tennessee 37831 (United States); Eaglesham, D.J.; Gossmann, H.; Jacobson, D.C.; Poate, J.M. [Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States)] [Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States); Erokhin, Y.E. [Eaton Corporation, 108 Cherry Hill Drive, Beverly, Massachusetts 01915 (United States)] [Eaton Corporation, 108 Cherry Hill Drive, Beverly, Massachusetts 01915 (United States)

    1997-06-01T23:59:59.000Z

    Extended defects from 5-, 2-, and 1-keV Si{sup +} ion implantation are investigated by transmission electron microscopy using implantation doses of 1 and 3{times}10{sup 14}cm{sup {minus}2} and annealing temperatures from 750 to 900{degree}C. Despite the proximity of the surface, {l_brace}311{r_brace}-type defects are observed even for 1 keV. Samples with a peak concentration of excess interstitials exceeding {approximately}1{percent} of the atomic density also contain some {l_brace}311{r_brace} defects which are corrugated across their width. These so-called zig-zag {l_brace}311{r_brace} defects are more stable than the ordinary {l_brace}311{r_brace} defects, having a dissolution rate at 750{degree}C which is ten times smaller. Due to their enhanced stability, the zig-zag {l_brace}311{r_brace} defects grow to lengths that are many times longer than their distance from the surface. It is proposed that zig-zag {l_brace}311{r_brace} defects form during the early stages of annealing by coalescence the high volume density of {l_brace}311{r_brace} defects confined within a very narrow implanted layer. These findings indicate that defect formation and dissolution will continue to control the interstitial supersaturation from ion implantation down to very low energies. {copyright} {ital 1997 American Institute of Physics.}

  1. Philosophy of mind and the problem of free will in the light of quantum mechanics

    E-Print Network [OSTI]

    Henry P. Stapp

    2008-05-01T23:59:59.000Z

    Defects occasioned by the advent of quantum mechanics are described in detail of recent arguments by John Searle and by Jaegwon Kim pertaining to the question of the complete reducibility to the physical of the apparent capacity of a person's conscious thoughts to affect the behaviour of that person's physically described brain.

  2. Atomistic simulations of structures and mechanical properties of polycrystalline diamond: Symmetrical S001< tilt grain boundaries

    E-Print Network [OSTI]

    Brenner, Donald W.

    Atomistic simulations of structures and mechanical properties of polycrystalline diamond for diamond to deposit as a polycrystalline film with a high density of grain boundaries and related defects structures and energies of symmetrical 001 tilt grain boundaries GB's in diamond have been calculated over

  3. Philosophy of Mind and the Problem of FreeWill in the Light of Quantum Mechanics.

    SciTech Connect (OSTI)

    Stapp, Henry; Stapp, Henry P

    2008-04-01T23:59:59.000Z

    Arguments pertaining to the mind-brain connection and to the physical effectiveness of our conscious choices have been presented in two recent books, one by John Searle, the other by Jaegwon Kim. These arguments are examined, and it is argued that the difficulties encountered arise from a defective understanding and application of a pertinent part of contemporary science, namely quantum mechanics.

  4. Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

    SciTech Connect (OSTI)

    Nguyen, Trung Dung; Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia)

    2014-05-05T23:59:59.000Z

    Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

  5. The corrosion behavior of DWPF glasses

    SciTech Connect (OSTI)

    Ebert, W.L.; Bates, J.K. [Argonne National Lab., IL (United States). Chemical Technology Div.

    1995-06-01T23:59:59.000Z

    The authors analyzed the corroded surfaces of reference glasses developed for the Defense Waste Processing Facility (DWPF) to characterize their corrosion behavior. The corrosion mechanism of nuclear waste glasses must be known in order to provide source terms describing radionuclide release for performance assessment calculations. Different DWPF reference glasses were corroded under conditions that highlighted various aspects of the corrosion process and led to different extents of corrosion. The glasses corroded by similar mechanisms, and a phenomenological description of their corrosion behavior is presented here. The initial leaching of soluble glass components results in the formation of an amorphous gel layer on the glass surface. The gel layer is a transient phase that transforms into a layer of clay crystallites, which equilibrates with the solution as corrosion continues. The clay layer does not act as a barrier to either water penetration or glass dissolution, which continues beneath it, and may eventually separate from the glass. Solubility limits for glass components may be established by the eventual precipitation of secondary phases; thus, corrosion of the glass becomes controlled by the chemical equilibrium between the solution and the assemblage of secondary phases. In effect, the solution is an intermediate phase through which the glass transforms to an energetically more favorable assemblage of phases. Implications regarding the prediction of long-term glass corrosion behavior are discussed.

  6. Atomic-scale investigation of point defects and hydrogen-solute atmospheres on the edge dislocation mobility in alpha iron

    SciTech Connect (OSTI)

    Bhatia, M. A.; Solanki, K. N., E-mail: kiran.solanki@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Groh, S. [Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg 09556 (Germany)

    2014-08-14T23:59:59.000Z

    In this study, we present atomistic mechanisms of 1/2 [111](11{sup Ż}0) edge dislocation interactions with point defects (hydrogen and vacancies) and hydrogen solute atmospheres in body centered cubic (bcc) iron. In metals such as iron, increases in hydrogen concentration can increase dislocation mobility and/or cleavage-type decohesion. Here, we first investigate the dislocation mobility in the presence of various point defects, i.e., change in the frictional stress as the edge dislocation interacts with (a) vacancy, (b) substitutional hydrogen, (c) one substitutional and one interstitial hydrogen, (d) interstitial hydrogen, (e) vacancy and interstitial hydrogen, and (f) two interstitial hydrogen. Second, we examine the role of a hydrogen-solute atmosphere on the rate of local dislocation velocity. The edge dislocation simulation with a vacancy in the compression side of the dislocation and an interstitial hydrogen atom at the tension side exhibit the strongest mechanical response, suggesting a higher potential barrier and hence, the higher frictional stress (i.e., ?83% higher than the pure iron Peierls stress). In the case of a dislocation interacting with a vacancy on the compressive side, the vacancy binds with the edge dislocation, resulting in an increase in the friction stress of about 28% when compared with the Peierls stress of an edge dislocation in pure iron. Furthermore, as the applied strain increases, the vacancy migrates through a dislocation transportation mechanism by attaining a velocity of the same order as the dislocation velocity. For the case of the edge dislocation interacting with interstitial hydrogen on the tension side, the hydrogen atom jumps through one layer perpendicular to the glide plane during the pinning-unpinning process. Finally, our simulation of dislocation interactions with hydrogen show first an increase in the local dislocation velocity followed by a pinning of the dislocation core in the atmosphere, resulting in resistance to dislocation motion as the dislocation moves though the hydrogen-solute atmospheres. With this systematic, atomistic study of the edge dislocation with various point defects, we show significant increase in obstacle strengths in addition to an increase in the local dislocation velocity during interaction with solute atmospheres. The results have implications for constitutive development and modeling of the hydrogen effect on dislocation mobility and deformation in metals.

  7. Preliminary Comparison of Reaction Rate theory and Object Kinetic Monte Carlo Simulations of Defect Cluster Dynamics under Irradiation

    SciTech Connect (OSTI)

    Stoller, Roger E [ORNL; Golubov, Stanislav I [ORNL; Becquart, C. S. [Universite de Lille; Domain, C. [EDF R& D, Clamart, France

    2006-09-01T23:59:59.000Z

    The multiscale modeling scheme encompasses models from the atomistic to the continuum scale. Phenomena at the mesoscale are typically simulated using reaction rate theory (RT), Monte Carlo (MC), or phase field models. These mesoscale models are appropriate for application to problems that involve intermediate length scales ( m to >mm), and timescales from diffusion (~ s) to long-term microstructural evolution (~years). Phenomena at this scale have the most direct impact on mechanical properties in structural materials of interest to nuclear energy systems, and are also the most accessible to direct comparison between the results of simulations and experiments. Recent advances in computational power have substantially expanded the range of application for MC models. Although the RT and MC models can be used simulate the same phenomena, many of the details are handled quite differently in the two approaches. A direct comparison of the RT and MC descriptions has been made in the domain of point defect cluster dynamics modeling, which is relevant to both the nucleation and evolution of radiation-induced defect structures. The relative merits and limitations of the two approaches are discussed, and the predictions of the two approaches are compared for specific irradiation conditions.

  8. Heavy Mobile Equipment Mechanic (One Mechanic Shop)

    Broader source: Energy.gov [DOE]

    The position is a Heavy Mobile Equipment Mechanic (One Mechanic Shop) located in Kent, Washington, and will be responsible for the safe and efficient operation of a field garage performing...

  9. Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling

    SciTech Connect (OSTI)

    Eapen, Jacob; Murty, Korukonda; Burchell, Timothy

    2014-06-02T23:59:59.000Z

    Disordering mechanisms in graphite have a long history with conflicting viewpoints. Using Raman and x-ray photon spectroscopy, electron microscopy, x-ray diffraction experiments and atomistic modeling and simulations, the current project has developed a fundamental understanding of early-to-late state radiation damage mechanisms in nuclear reactor grade graphite (NBG-18 and PCEA). We show that the topological defects in graphite play an important role under neutron and ion irradiation.

  10. In-situ observation of the energy dependence of defect production in Cu and Ni

    SciTech Connect (OSTI)

    King, W.E.; Merkel, K.L.; Baily, A.C.; Haga, K.; Meshii, M.

    1983-01-01T23:59:59.000Z

    The damage function, the average number of Frenkel pairs created as a function of lattice atom recoil energy, was investigated in Cu and Ni using in-situ electrical-resistivity damage-rate measurements in the high-voltage electron micrscope (HVEM) at T < 10K. Electron and proton irradiations were performed in-situ on the same polycrystalline specimens using the Argonne National Laboratory HVEM-Ion Beam Interface. Both Ni and Cu exhibit a sharp rise in the damage function above the minimum threshold energy (approx. 18 eV for Cu and approx. 20 eV for Ni) as displacements in the low-threshold energy regions of the threshold energy surface become possible. A plateau is observed for both materials (0.54 Frenkel pairs for Cu and 0.46 Frenkel pairs for Ni) indicating that no further directions become productive until much higher recoil energies. These damage functions show strong deviations from simple theoretical models, such as the Modified Kinchin-Pease damage function. The results are discussed in terms of the mechanisms of defect production that govern the single-displacement regime of the damage function and are compared with results from recent molecular-dynamics simulations.

  11. Electrodes mitigating effects of defects in organic electronic devices

    DOE Patents [OSTI]

    Heller, Christian Maria Anton (Albany, NY)

    2008-05-06T23:59:59.000Z

    A compound electrode for organic electronic devices comprises a thin first layer of a first electrically conducting material and a second electrically conducting material disposed on the first layer. In one embodiment, the second electrically conducting material is formed into a plurality of elongated members. In another embodiment, the second material is formed into a second layer. The elongated members or the second layer has a thickness greater than that of the first layer. The second layer is separated from the first layer by a conducting material having conductivity less than at least the material of the first layer. The compound electrode is capable of mitigating adverse effects of defects, such as short circuits, in the construction of the organic electronic devices, and can be included in light-emitting or photovoltaic devices.

  12. Defect localization, characterization and reliability assessment in emerging photovoltaic devices.

    SciTech Connect (OSTI)

    Yang, Benjamin Bing-Yeh; Cruz-Campa, Jose Luis; Haase, Gad S.; Tangyunyong, Paiboon; Cole, Edward Isaac,; Okandan, Murat; Nielson, Gregory N.

    2014-04-01T23:59:59.000Z

    Microsystems-enabled photovoltaics (MEPV) can potentially meet increasing demands for light-weight, portable, photovoltaic solutions with high power density and efficiency. The study in this report examines failure analysis techniques to perform defect localization and evaluate MEPV modules. CMOS failure analysis techniques, including electroluminescence, light-induced voltage alteration, thermally-induced voltage alteration, optical beam induced current, and Seabeck effect imaging were successfully adapted to characterize MEPV modules. The relative advantages of each approach are reported. In addition, the effects of exposure to reverse bias and light stress are explored. MEPV was found to have good resistance to both kinds of stressors. The results form a basis for further development of failure analysis techniques for MEPVs of different materials systems or multijunction MEPVs. The incorporation of additional stress factors could be used to develop a reliability model to generate lifetime predictions for MEPVs as well as uncover opportunities for future design improvements.

  13. Periodic Schrödinger operators with local defects and spectral pollution

    E-Print Network [OSTI]

    Eric Cancčs; Virginie Ehrlacher; Yvon Maday

    2011-11-16T23:59:59.000Z

    This article deals with the numerical calculation of eigenvalues of perturbed periodic Schr\\"odinger operators located in spectral gaps. Such operators are encountered in the modeling of the electronic structure of crystals with local defects, and of photonic crystals. The usual finite element Galerkin approximation is known to give rise to spectral pollution. In this article, we give a precise description of the corresponding spurious states. We then prove that the supercell model does not produce spectral pollution. Lastly, we extend results by Lewin and S\\'er\\'e on some no-pollution criteria. In particular, we prove that using approximate spectral projectors enables one to eliminate spectral pollution in a given spectral gap of the reference periodic Sch\\"odinger operator.

  14. Directed polymers in a random environment with a defect line

    E-Print Network [OSTI]

    Kenneth S. Alexander; Gökhan Y?ld?r?m

    2015-01-21T23:59:59.000Z

    We study the depinning transition of the $1+1$ dimensional directed polymer in a random environment with a defect line. The random environment consists of i.i.d. potential values assigned to each site of $\\mathbb{Z}^2$; sites on the positive axis have the potential enhanced by a deterministic value $u$. We show that for small inverse temperature $\\beta$ the quenched and annealed free energies differ significantly at most in a small neighborhood (of size of order $\\beta$) of the annealed critical point $u_c^a=0$. For the case $u=0$, we show that the difference between quenched and annealed free energies is of order $\\beta^4$ as $\\beta\\to 0$, assuming only finiteness of exponential moments of the potential values, improving existing results which required stronger assumptions.

  15. Defects and diffusion in MeV implanted silicon

    SciTech Connect (OSTI)

    Venezia, V. C.; Haynes, T. E.; Agarwal, Aditya; Gossmann, H.-J.; Pelaz, L.; Jacobson, D. C.; Eaglesham, D. J.; Duggan, J. L. [Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States); Solid State Division, Oak Ridge National Laboratory, MS-6048, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Semiconductor Equipment Operations, Eaton Corporation, 55 Cherry Hill Drive, Beverly, Massachusetts 01915 (United States); Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States); Department of Physics, University of North Texas, Denton, Texas 76201 (United States)

    1999-06-10T23:59:59.000Z

    In this work we demonstrate that the defects that are created by 2-MeV Si ions can interact with dopant atoms both during implantation and during post-implant annealing. We show that the interstitials and vacancies created during MeV Si implantation result in a radiation enhanced diffusion of B and Sb markers, respectively, when the temperature of implantation is above the threshold temperature for formation of mobile dopant complexes. With the use of these dopant markers we also demonstrate that a vacancy-rich near surface region results during post-implant annealing of MeV implanted silicon. The depth distribution and the thermal evolution of clustered vacancies was measured by a Au labeling technique.

  16. Ion beam collimating grid to reduce added defects

    DOE Patents [OSTI]

    Lindquist, Walter B. (Oakland, CA); Kearney, Patrick A. (Livermore, CA)

    2003-01-01T23:59:59.000Z

    A collimating grid for an ion source located after the exit grid. The collimating grid collimates the ion beamlets and disallows beam spread and limits the beam divergence during transients and steady state operation. The additional exit or collimating grid prevents beam divergence during turn-on and turn-off and prevents ions from hitting the periphery of the target where there is re-deposited material or from missing the target and hitting the wall of the vessel where there is deposited material, thereby preventing defects from being deposited on a substrate to be coated. Thus, the addition of a collimating grid to an ion source ensures that the ion beam will hit and be confined to a specific target area.

  17. Intracardiac Echocardiography Evaluation in Secundum Atrial Septal Defect Transcatheter Closure

    SciTech Connect (OSTI)

    Zanchetta, Mario; Pedon, Luigi; Rigatelli, Gianluca; Carrozza, Antonio; Zennaro, Marco; Di Martino, Roberta [Department of Cardiovascular Disease, Cittadella General Hospital, Cittadella, Padua (Italy); Onorato, Eustaquio [Operative Unit ofCardiology, Clinica S. Rocco, Ome, Brescia (Italy); Maiolino, Pietro [Department of Cardiovascular Disease, Cittadella General Hospital, Cittadella, Padua (Italy)

    2003-02-15T23:59:59.000Z

    Purpose: This study was designed to assess the balloon sizing maneuvers and deployment of an Amplatzer Septal Occluder (ASO). In addition, intraprocedural balloon sizing was compared with off-line intracardiac echocardiographic measurements. Methods: The intracardiac echocardiography (ICE) measurements were: maximum transverse and longitudinal atrial septal defect (ASD) diameters in the aortic valve and four-chamber planes;area of the ASD and its equivalent circle diameter. Thirteen consecutive patients underwent transcatheter implantation of an ASO device using ICE guidance under local anesthesia. The device matching the balloon sizing diameter of the defect was implanted. Qualitative ICE assessment of the ASO devices implanted was performed off line. Results: The mean equivalent circle diameter predicted by ICE was 24.40 {+-} 5.61 mm and was significantly higher(p 0.027) than the ASD measured by balloonsizing (21.38 {+-} 5.28 mm). Unlike previous studies we did not find any correlation between the two measurements (correlation coefficient = 0.47). Only four of the 13 patients had optimal device positioning as shown by the qualitative ICE evaluation, whereas the remaining nine patients had inadequate device placement. This resulted in a waist diameter that was an average 26.1% undersized in seven patients and 12.7% oversized in two patients. Five of the seven patients with an undersized device had ASO-atrial septum misalignment with leftward device deviation. Conclusion: The ICE images allowed careful measurement of the dimensions of the ASD and accurately displayed the spatial relations of the ASO astride the ASD.Moreover, use of the ICE measurement led to selection of a different size of device in comparison with those of balloon sizing. The clinical benefit of this new approach needs to be rigorously tested.

  18. Yield improvement and defect reduction in steel casting

    SciTech Connect (OSTI)

    Kent Carlson

    2004-03-16T23:59:59.000Z

    This research project investigated yield improvement and defect reduction techniques in steel casting. Research and technology development was performed in the following three specific areas: (1) Feeding rules for high alloy steel castings; (2) Unconventional yield improvement and defect reduction techniques--(a) Riser pressurization; and (b) Filling with a tilting mold; and (3) Modeling of reoxidation inclusions during filling of steel castings. During the preparation of the proposal for this project, these areas were identified by the High Alloy Committee and Carbon and Low Alloy Committee of the Steel Founders' Society of America (SFSA) as having the highest research priority to the steel foundry industry. The research in each of the areas involved a combination of foundry experiments, modeling and simulation. Numerous SFSA member steel foundries participated in the project through casting trials and meetings. The technology resulting from this project will result in decreased scrap and rework, casting yield improvement, and higher quality steel castings produced with less iteration. This will result in considerable business benefits to steel foundries, primarily due to reduced energy and labor costs, increased capacity and productivity, reduced lead-time, and wider use and application of steel castings. As estimated using energy data provided by the DOE, the technology produced as a result of this project will result in an energy savings of 2.6 x 10{sup 12} BTU/year. This excludes the savings that were anticipated from the mold tilting research. In addition to the energy savings, and corresponding financial savings this implies, there are substantial environmental benefits as well. The results from each of the research areas listed above are summarized.

  19. Effect of defect imbalance on void swelling distributions produced in pure iron irradiated with 3.5 MeV self-ions

    SciTech Connect (OSTI)

    Lin Shao; C.-C. Wei; J. Gigax; A. Aitkaliyeva; D. Chen; B.H. Sencer; F.A. Garner

    2014-10-01T23:59:59.000Z

    Ion irradiation has been widely used to simulate neutron-induced radiation damage. There are a number of features of ion-induced damage that differ from neutron-induced damage, however, and these differences require investigation before ion data can be confidently used to predict behavior arising from neutron bombardment. In this study 3.5 MeV self-ion irradiation of pure iron was used to study the influence on void swelling of the depth-dependent defect imbalance between vacancies and interstitials that arises from various surface effects, forward scattering of displaced atoms, and especially the injected interstitial effect. It was observed that the depth dependence of void swelling does not follow the behavior anticipated from the depth dependence of the damage rate. Void nucleation and growth develop first in the lower-dose, near-surface region, and then moves to progressively deeper and higher-damage depths during continued irradiation. This indicates a strong initial suppression of void nucleation in the peak damage region that is eventually overcome with continued irradiation. Using the Boltzmann transport equation method, this phenomenon is shown to be due to depth-dependent defect imbalances created under ion irradiation. These findings demonstrate that void swelling does not depend solely on the local dose level and that this sensitivity of swelling to depth must be considered in extraction and interpretation of ion-induced swelling data. 2014 El

  20. 76 PostErs EMBnet.journal 19.B An ontology describing congenital heart defects data

    E-Print Network [OSTI]

    76 PostErs EMBnet.journal 19.B An ontology describing congenital heart defects data Charalampos interests: the authors have declared that no competing interests exist. Abstract Congenital heart defects (CHDs) are a group of diseases characterized by a structural anomaly of the heart that is pre- sent

  1. Towards Fault-Tolerant Digital Microfluidic Lab-on-Chip: Defects, Fault Modeling, Testing, and Reconfiguration

    E-Print Network [OSTI]

    Chakrabarty, Krishnendu

    Towards Fault-Tolerant Digital Microfluidic Lab-on-Chip: Defects, Fault Modeling, Testing, NC 27708, USA Abstract Dependability is an important attribute for microfluidic lab-on-chip devices microfluidic lab-on-chip systems. Defects are related to logical fault models that can be viewed not only

  2. Stone-Wales defects in graphene and other planar sp2 -bonded materials

    E-Print Network [OSTI]

    Alfč, Dario

    Stone-Wales defects in graphene and other planar sp2 -bonded materials Jie Ma,1,2,3 Dario Alfč,2 that the structure of the Stone-Wales SW defect in graphene is more complex than hitherto appreciated. Rather than of graphene and in so doing modify its chemical re- activity toward adsorbates, and likely impact upon its

  3. Electrochemical method for defect delineation in silicon-on-insulator wafers

    DOE Patents [OSTI]

    Guilinger, Terry R. (Albuquerque, NM); Jones, Howland D. T. (Albuquerque, NM); Kelly, Michael J. (Albuquerque, NM); Medernach, John W. (Albuquerque, NM); Stevenson, Joel O. (Albuquerque, NM); Tsao, Sylvia S. (Albuquerque, NM)

    1991-01-01T23:59:59.000Z

    An electrochemical method for defect delineation in thin-film SOI or SOS wafers in which a surface of a silicon wafer is electrically connected so as to control the voltage of the surface within a specified range, the silicon wafer is then contacted with an electrolyte, and, after removing the electrolyte, defects and metal contamination in the silicon wafer are identified.

  4. Hydrogen interaction with point defects in tungsten K. Heinola, T. Ahlgren, K. Nordlund, and J. Keinonen

    E-Print Network [OSTI]

    Nordlund, Kai

    Hydrogen interaction with point defects in tungsten K. Heinola, T. Ahlgren, K. Nordlund, and J-principles calculations were used in determining the binding and trapping properties of hydrogen to point defects in tungsten. Hydrogen zero-point vibrations were taken into account. It was concluded that the monovacancy can

  5. Atomistic calculations of defects in ZnGeP2 Peter Zapol and Ravindra Pandeya)

    E-Print Network [OSTI]

    Pandey, Ravi

    for native ionic defects and binding energies for some of the electronic defect complexes are calculated, Michigan Technological University, Houghton, Michigan 49931 Mel Ohmer Wright Laboratory, Wright, Technology and Medicine, South Kensington, SW7 2AY London, United Kingdom Received 5 June 1995; accepted

  6. Atomistic Modeling of Native Point Defects in Yttrium Aluminum Garnet Crystals

    E-Print Network [OSTI]

    Pandey, Ravi

    and Ravindra Pandey Department of Physics, Michigan Technological University, Houghton, Michigan 49931 Native, and dielectric constants of YAG very well. The calculated formulation energies for native defects sug- gestAtomistic Modeling of Native Point Defects in Yttrium Aluminum Garnet Crystals Maija M. Kuklja

  7. Unifying power-law behaviour, functionality and defect distribution in general software

    E-Print Network [OSTI]

    Hatton, Les

    Unifying power-law behaviour, functionality and defect distribution in general software systems Les between power-law distribution of component sizes and defect growth in maturing software systems. It was further noted that power-law distributions appear to be present in software systems from the beginning

  8. Impurity-defect interaction in polycrystalline silicon for photovoltaic applications. The role of hydrogen

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    655 Impurity-defect interaction in polycrystalline silicon for photovoltaic applications. The role of hydrogen A. Chari, P. de Mierry, A. Menikh and M. Aucouturier Laboratoire de Physique des Solides, C silicon, passivation of recombining defects by hydrogen, hydrogen-dopant interaction. A more focused

  9. Shape defect detection in ferrite cores Judit Verest'oy and Dmitry Chetverikov

    E-Print Network [OSTI]

    Chetverikov, Dmitry

    Shape defect detection in ferrite cores Judit Verest'oy and Dmitry Chetverikov Computer. The method is applied to the visual inspection and dimensional measurement of ferrite cores. An optical shape defects may deteriorate any of the dimensions. Key words: image analysis, industrial inspection, ferrite

  10. Detecting shape defects in ferrite cores \\Lambda Dmitry Chetverikov and Judit Verest'oy

    E-Print Network [OSTI]

    Chetverikov, Dmitry

    Detecting shape defects in ferrite cores \\Lambda Dmitry Chetverikov and Judit Verest'oy Computer of the objects. The method is applied to the visual inspection and dimensional measurement of ferrite cores CIPA­CT94 0153 CRASH (for CRAck and SHape defect detection in ferrite cores) which has been in progress

  11. An Approach to Detect the Origin and Distribution of Software Defects in an Evolving

    E-Print Network [OSTI]

    Ulm, Universität

    -Physical System Christian Manz1 , Michael Schulze2 , and Manfred Reichert3 1 Group Research & Advanced Engineering is necessary to ensure a reliable software defect removal. Particularly, de- tecting software defects. Keywords: Software Product Line, Evolution, Maintenance 1 Introduction Cyber-Physical Systems (CPS), like

  12. Robotic Tracking and Marking of Surface Shape Defects on Moving Automotive Panels

    E-Print Network [OSTI]

    Payeur, Pierre

    defects for quality control in the automotive industry. In order to integrate a defects detection station. INTRODUCTION Quality control in the automotive industry is essential in order to ensure that the products meet of the automotive panels, the pose and motion estimator (PME) needs to be robust to the complexity of industrial

  13. Using Explicit and Machine-Understandable Engineering Knowledge for Defect Detection in Automation Systems Engineering

    E-Print Network [OSTI]

    industrial complexes are very high. Traditional approaches for defect detection in automation systems and data models which are used within the engineering of industrial automation systems. Thus, some defects Nowadays, industrial automation systems have tendencies to become more and more complex and large

  14. Characterization of the nitrogen split interstitial defect in wurtzite aluminum nitride using density functional theory

    SciTech Connect (OSTI)

    Szállás, A., E-mail: szallas.attila@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Szász, K. [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Institute of Physics, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary); Trinh, X. T.; Son, N. T.; Janzén, E. [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Gali, A., E-mail: gali.adam@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest (Hungary)

    2014-09-21T23:59:59.000Z

    We carried out Heyd-Scuseria-Ernzerhof hybrid density functional theory plane wave supercell calculations in wurtzite aluminum nitride in order to characterize the geometry, formation energies, transition levels, and hyperfine tensors of the nitrogen split interstitial defect. The calculated hyperfine tensors may provide useful fingerprint of this defect for electron paramagnetic resonance measurement.

  15. Electrical characterisation of defects in polycrystalline B-doped diamond films

    E-Print Network [OSTI]

    Bristol, University of

    applied to B-doped thin polycrystalline diamond films deposited on p+ -silicon by hot filament chemical]. Recently valuable information about defects in monocrystalline [3] and polycrystalline [7] diamond filmsElectrical characterisation of defects in polycrystalline B-doped diamond films O. S. Elsherif 1, a

  16. Fermi Level Control of Point Defects During Growth of Mg-Doped GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    Fermi Level Control of Point Defects During Growth of Mg-Doped GaN ZACHARY BRYAN,1,4 MARC HOFFMANN defects during metalorganic chem- ical vapor deposition (MOCVD) of Mg-doped GaN has been demonstrated of magnitude lower resistivity values compared with typical unan- nealed GaN:Mg samples. The PL spectra

  17. DuoTracker: Tool Support for Software Defect Data Collection and Analysis

    E-Print Network [OSTI]

    Dascalu, Sergiu

    evaluate their process using either the Capability Maturity Model (CMM) [3] or the ISO 9001 standards [4 software processes. Keywords--software defects; software anomalies; defect classification; PSP; CMM; IS0-9001 is then compared against the quality models of CMM or IS0 9001. There are also improvement methods such as IDEAL [5

  18. Dynamics of Johari-Goldstein ? relaxation and its universal relation to ? relaxation in bulk metallic glasses by mechanical spectroscopy

    SciTech Connect (OSTI)

    Wu, Xuebang, E-mail: xbwu@issp.ac.cn; Guo, Lijun; Liu, C. S. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei, Anhui (China)

    2014-06-14T23:59:59.000Z

    The dynamics of the Johari–Goldstein (JG) ? relaxation and the ? relaxation in bulk metallic glasses (MGs) has been investigated by using mechanical spectroscopy combined with the Coupling Model. The ? relaxations of MGs exhibit different behaviors such as peaks, humps, and excess wings due to the different fluctuations of the chemical interactions among the constituting atoms. A universal correlation between the ? relaxation and the ? relaxation is generally found by their activation energies and relaxation times as well as the non-exponentiality parameter of the ? relaxation, which can be predicted quantitatively from the Coupling Model. Based on the quasi-point defects theory, a correlation factor ? shows a broad peak along with the ? relaxation, suggesting that the concentration and the correlation degree of the string-like configurations involved in the ? relaxation vary with increasing temperature, which challenges the previous view that the system is in an iso-configuration state below T{sub g} and may shed new light on the nature of the JG ? relaxation in metallic glasses.

  19. Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies

    SciTech Connect (OSTI)

    Vijayakumar, M.; Hu, Jian Z.

    2013-10-15T23:59:59.000Z

    To analyze the lithium ion interaction with realistic graphene surfaces, we carried out dispersion corrected DFT-D3 studies on graphene with common point defects and chemisorbed oxygen containing functional groups along with defect free graphene surface. Our study reveals that, the interaction between lithium ion (Li+) and graphene is mainly through the delocalized ? electron of pure graphene layer. However, the oxygen containing functional groups pose high adsorption energy for lithium ion due to the Li-O ionic bond formation. Similarly, the point defect groups interact with lithium ion through possible carbon dangling bonds and/or cation-? type interactions. Overall these defect sites render a preferential site for lithium ions compared with pure graphene layer. Based on these findings, the role of graphene surface defects in lithium battery performance were discussed.

  20. Delocalised oxygen as the origin of two-level defects in Josephson junctions

    E-Print Network [OSTI]

    Timothy C. DuBois; Manolo C. Per; Salvy P. Russo; Jared H. Cole

    2012-12-07T23:59:59.000Z

    One of the key problems facing superconducting qubits and other Josephson junction devices is the decohering effects of bi-stable material defects. Although a variety of phenomenological models exist, the true microscopic origin of these defects remains elusive. For the first time we show that these defects may arise from delocalisation of the atomic position of the oxygen in the oxide forming the Josephson junction barrier. Using a microscopic model, we compute experimentally observable parameters for phase qubits. Such defects are charge neutral but have non-zero response to both applied electric field and strain. This may explain the observed long coherence time of two-level defects in the presence of charge noise, while still coupling to the junction electric field and substrate phonons.

  1. Thermodynamics of fission products in dispersion fuel designs - first principles modeling of defect behavior in bulk and at interfaces

    SciTech Connect (OSTI)

    Liu, Xiang-yand [Los Alamos National Laboratory; Uberuaga, Blas P [Los Alamos National Laboratory; Nerikar, Pankaj [Los Alamos National Laboratory; Sickafus, Kurt E [Los Alamos National Laboratory; Stanek, Chris R [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    Density functional theory (DFT) calculations of fission product (Xe, Sr, and Cs) incorporation and segregation in alkaline earth metal oxides, HfO{sub 2} and UO{sub 2} oxides, and the MgO/(U, Hf, Ce)O{sub 2} interfaces have been carried out. In the case of UO{sub 2}, the calculations were performed using spin polarization and with a Hubbard U term characterizing the on-sit Coulomb repulsion between the localized 5f electrons. The fission product solution energies in bulk UO{sub 2{+-}x} have been calculated as a function of non-stoichiometry x, and were compared to that in MgO. These calculations demonstrate that the fission product incorporation energies in MgO are higher than in HfO{sub 2}. However, this trend is reversed or reduced for alkaline earth oxides with larger cation sizes. The solution energies of fission products in MgO are substantially higher than in UO{sub 2{+-}x}, except for the case of Sr in the hypostoichiometric case. Due to size effects, the thermodynamic driving force of segregation for Xe and Cs from bulk MgO to the MgO/fluorite interface is strong. However, this driving force is relatively weak for Sr.

  2. Health Behavior Health Promotion -Prevention

    E-Print Network [OSTI]

    Meagher, Mary

    chronic disease complications Improve quality of life Reduce health care costs #12;ImpactHealth Behavior Health Promotion - Prevention Modification of Health Attitudes and Health Behavior #12;Health Promotion: An Overview Basic philosophy Good health = individual and collective goal

  3. Mechanical & Industrial Engineering

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Mechanical & Industrial Engineering 1 Welcome MIE Industrial Advisory Board October 15, 2010 #12;Mechanical & Industrial Engineering 2 MIE Dorothy Adams Undergraduate/Graduate Secretary David Schmidt Associate Professor & Graduate Program Director #12;Mechanical & Industrial Engineering 3 MIE James Rinderle

  4. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has · STOP (Structural, Thermal, and Optical Performance) analyses of optical systems Thermal engineers lead evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

  5. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    and the Department of Mechanical Engineering Tufts University Retooling Our Energy Ecosystem: challengesMechanical engineering Department Seminar Robert J. Hannemann The Gordon Institute and Chair of the Tufts Department of Mechanical Engineering. His technical and academic interests

  6. Interaction of Sn atoms with defects introduced by ion implantation in Ge substrate

    SciTech Connect (OSTI)

    Taoka, Noriyuki, E-mail: ntaoka@alice.xtal.nagoya-u.ac.jp; Fukudome, Motoshi; Takeuchi, Wakana; Arahira, Takamitsu; Sakashita, Mitsuo; Nakatsuka, Osamu; Zaima, Shigeaki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2014-05-07T23:59:59.000Z

    The interaction of Sn atoms with defects induced by Sn implantation of Ge substrates with antimony (Sb) as an n-type dopant and the impact of H{sub 2} annealing on these defects were investigated by comparison with defects induced by Ge self-implantation. In the Ge samples implanted with either Sn or Ge, and annealed at temperatures of less than 200?°C, divacancies, Sb-vacancy complexes with single or double acceptor-like states, and defects related to Sb and interstitial Ge atoms were present. On the other hand, after annealing at 500?°C in an N{sub 2} or H{sub 2} atmosphere, defects with different structures were observed in the Sn-implanted samples by deep level transition spectroscopy. The energy levels of the defects were 0.33?eV from the conduction band minimum and 0.55?eV from the valence band maximum. From the capacitance-voltage (C-V) characteristics, interaction between Sn atoms and defects after annealing at 500?°C was observed. The effect of H{sub 2} annealing at around 200?°C was observed in the C-V characteristics, which can be attributed to hydrogen passivation, and this effect was observed in both the Ge- and Sn-implanted samples. These results suggest the presence of defects that interact with Sn or hydrogen atoms. This indicates the possibility of defect control in Ge substrates by Sn or hydrogen incorporation. Such defect control could yield high-performance Ge-based devices.

  7. Transient behavior of ultracapacitors and supercapacitors

    SciTech Connect (OSTI)

    Huggins, R.A. [Center for Solar Energy and Hydrogen Research, Ulm (Germany)

    1995-12-31T23:59:59.000Z

    Several different mechanisms can be used to provide short term high power pulses from electrochemical systems. Their fundamental characteristics and applicability to the different types of transient output requirements will be discussed. When significant amounts of energy must be delivered, the most favorable materials operate by means of insertion reactions. The methods that can be employed to quantitatively evaluate the critical materials parameters will be described. Spreadsheet techniques are especially useful for modeling the transient transport behavior of components containing such materials under various boundary conditions. LaPlace transform methods can then be used to convert information about the parameters of individual components into the dynamic response of the total system.

  8. Energy Performance and Home Owner Behavior

    E-Print Network [OSTI]

    Dong, B.

    2013-01-01T23:59:59.000Z

    ME 4343 HVAC Design The Impact of Occupancy Behavior Patterns On the Energy Consumption in Low-income Residential Buildings Bing Dong1, Yifei Duan1, Rui Liu2, Taeg Nishimoto2 1 Building Performance and Diagnostics Group, Mechanical Engineering..., the University of Texas, San Antonio, TX, USA 2 College of Architecture, the University of Texas, San Antonio, TX, USA ESL-KT-13-12-04 CATEE 2013: Clean Air Through Energy Efficiency Conference, San Antonio, Texas Dec. 16-18 Introduction • Large gaps between...

  9. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering It is a new beginning for innovative fundamental and applied and consolidation of bulk nanocrystalline materials using mechanical alloying, the alloy development and synthesis

  10. Ion Hydration and Associated Defects in Hydrogen Bond Network of Water: Observation of Reorientationally Slow Water Molecules Beyond First Hydration Shell in Aqueous Solutions of MgCl$_2$

    E-Print Network [OSTI]

    Upayan Baul; Satyavani Vemparala

    2014-12-18T23:59:59.000Z

    Effects of presence of ions, at moderate to high concentrations, on dynamical properties of water molecules are investigated through classical molecular dynamics simulations using two well known non-polarizable water models. Simulations reveal that the presence of magnesium chloride (MgCl$_2$) induces perturbations in the hydrogen bond network of water leading to the formation of bulk-like domains with \\textquoteleft defect sites\\textquoteright~on boundaries of such domains: water molecules at such defect sites have less number of hydrogen bonds than those in bulk water. Reorientational autocorrelation functions for dipole vectors of such defect water molecules are computed at different concentrations of ions and compared with system of pure water. Earlier experimental and simulation studies indicate significant differences in reorientational dynamics for water molecules in the first hydration shell of many dissolved ions. Results of this study suggest that defect water molecules, which are beyond the first hydration shells of ions, also experience significant slowing down of reorientation times as a function of concentration in the case of MgCl$_2$. However, addition of cesium chloride(CsCl) to water does not perturb the hydrogen bond network of water significantly even at higher concentrations. This difference in behavior between MgCl$_2$ and CsCl is consistent with the well-known Hofmeister series.

  11. Investigation of deep-level defects in Cu(In,Ga)Se{sub 2} thin films by a steady-state photocapacitance method

    SciTech Connect (OSTI)

    Hu, Xiaobo, E-mail: hxb1314@gmail.com; Sakurai, Takeaki; Akimoto, Katsuhiro [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Yamada, Akimasa; Ishizuka, Shogo; Niki, Sigeru [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-10-28T23:59:59.000Z

    The properties of defect levels located 0.8?eV above the valence band in Cu(In{sub 1?x},Ga{sub x})Se{sub 2} thin films were investigated by a steady-state photocapacitance method. When illuminated by light with a photon energy of 0.8?eV at 60?K, a fast increase, followed by a slow increase, was observed in the photocapacitance transients of all samples. Upon being re-exposed, samples with a low bandgap energy showed a slow decrease in photocapacitance transients. These observations were interpreted using a configuration coordinate model assuming two states for the 0.8?eV defect: a stable state D and its metastable state D* with a large lattice relaxation. The difference in the evolution mechanisms of the photocapacitance transients was attributed to the difference in the optical transition of carriers between the two states of the 0.8?eV defect and the valence and conduction bands.

  12. The Influence of Friendship Networks on Adolescents' Health-Risk Behaviors: A Social Network Analysis

    E-Print Network [OSTI]

    Jeon, Kwon Chan

    2014-12-15T23:59:59.000Z

    Friendships among adolescents can exert significant influence on behaviors that pose risk to their health. However, empirical evidence for friendships’ influence is mixed due to various factors. Among these factors, are the complex mechanisms...

  13. Characteristics of syntactic processing : an examination utilizing behavioral and fMRI techniques

    E-Print Network [OSTI]

    Chen, Evan, 1975-

    2004-01-01T23:59:59.000Z

    This thesis explores two important factors that constrain the syntactic parser of the sentence processing mechanism, syntactic storage costs and plausibility information. It uses behavioral methods to explore the characteristics ...

  14. Atomistics of defect nucleation and mobility : dislocations and twinning

    E-Print Network [OSTI]

    Chang, Jinpeng, 1974-

    2003-01-01T23:59:59.000Z

    Multiscale materials modeling has emerged in recent years as a significant concept and the only viable approach to understand the mechanical response of materials by linking modeling research at different length scales and ...

  15. Acceleration of dormant storage effects to address the reliability of silicon surface micromachined Micro-Electro-Mechanical Systems (MEMS).

    SciTech Connect (OSTI)

    Cox, James V.; Candelaria, Sam A.; Dugger, Michael Thomas; Duesterhaus, Michelle Ann; Tanner, Danelle Mary; Timpe, Shannon J.; Ohlhausen, James Anthony; Skousen, Troy J.; Jenkins, Mark W.; Jokiel, Bernhard, Jr.; Walraven, Jeremy Allen; Parson, Ted Blair

    2006-06-01T23:59:59.000Z

    Qualification of microsystems for weapon applications is critically dependent on our ability to build confidence in their performance, by predicting the evolution of their behavior over time in the stockpile. The objective of this work was to accelerate aging mechanisms operative in surface micromachined silicon microelectromechanical systems (MEMS) with contacting surfaces that are stored for many years prior to use, to determine the effects of aging on reliability, and relate those effects to changes in the behavior of interfaces. Hence the main focus was on 'dormant' storage effects on the reliability of devices having mechanical contacts, the first time they must move. A large number ({approx}1000) of modules containing prototype devices and diagnostic structures were packaged using the best available processes for simple electromechanical devices. The packaging processes evolved during the project to better protect surfaces from exposure to contaminants and water vapor. Packages were subjected to accelerated aging and stress tests to explore dormancy and operational environment effects on reliability and performance. Functional tests and quantitative measurements of adhesion and friction demonstrated that the main failure mechanism during dormant storage is change in adhesion and friction, precipitated by loss of the fluorinated monolayer applied after fabrication. The data indicate that damage to the monolayer can occur at water vapor concentrations as low as 500 ppm inside the package. The most common type of failure was attributed to surfaces that were in direct contact during aging. The application of quantitative methods for monolayer lubricant analysis showed that even though the coverage of vapor-deposited monolayers is generally very uniform, even on hidden surfaces, locations of intimate contact can be significantly depleted in initial concentration of lubricating molecules. These areas represent defects in the film prone to adsorption of water or contaminants that can cause movable structures to adhere. These analysis methods also indicated significant variability in the coverage of lubricating molecules from one coating process to another, even for identical processing conditions. The variability was due to residual molecules left in the deposition chamber after incomplete cleaning. The coating process was modified to result in improved uniformity and total coverage. Still, a direct correlation was found between the resulting static friction behavior of MEMS interfaces, and the absolute monolayer coverage. While experimental results indicated that many devices would fail to start after aging, the modeling approach used here predicted that all the devices should start. Adhesion modeling based upon values of adhesion energy from cantilever beams is therefore inadequate. Material deposition that bridged gaps was observed in some devices, and potentially inhibits start-up more than the adhesion model indicates. Advances were made in our ability to model MEMS devices, but additional combined experimental-modeling studies will be needed to advance the work to a point of providing predictive capability. The methodology developed here should prove useful in future assessments of device aging, however. Namely, it consisted of measuring interface properties, determining how they change with time, developing a model of device behavior incorporating interface behavior, and then using the age-aware interface behavior model to predict device function.

  16. Characteristic Behavior of Polymer Electrolyte Fuel Cell Resistance during Cold Start

    E-Print Network [OSTI]

    Mench, Matthew M.

    a Department of Mechanical and Nuclear Engineering, Fuel Cell Dynamics and Diagnostics LaboratoryCharacteristic Behavior of Polymer Electrolyte Fuel Cell Resistance during Cold Start Charles fuel cell from -10°C to charac- terize high-frequency resistance behavior, water motion, and ice

  17. Effects of stretching and cycling on the fatigue behavior of polymer-supported Ag thin films

    E-Print Network [OSTI]

    Effects of stretching and cycling on the fatigue behavior of polymer-supported Ag thin films Gi March 2013 Keywords: Fatigue Thin films Fatigue crack initiation Intergranular failure Ductile fracture on characterizing the mechanical behavior of thin metal films and have observed that metals in thin-film form can

  18. Drug-evoked synaptic plasticity and addictive behavior, a causal relationship?

    E-Print Network [OSTI]

    Fukai, Tomoki

    Drug-evoked synaptic plasticity and addictive behavior, a causal relationship? Christian Luescher principal interest is on drug reward and how exposure to addictive substances can change behavior in rodent models of addiction. "Drug-evoked synaptic plasticity" has emerged as a mechanism underlying drug

  19. Combined Quantum Mechanical and Molecular Mechanics Studies of...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in Combined Quantum Mechanical and Molecular Mechanics Studies of the...

  20. Studies on intrinsic defects related to Zn vacancy in ZnO nanoparticles

    SciTech Connect (OSTI)

    Singh, V.P. [School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi, 221005 (India)] [School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi, 221005 (India); Das, D. [UGC-DAE Consortium for Scientific Research, Kolkata Centre (India)] [UGC-DAE Consortium for Scientific Research, Kolkata Centre (India); Rath, Chandana, E-mail: chandanarath@yahoo.com [School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi, 221005 (India)] [School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi, 221005 (India)

    2013-02-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? Williamson–Hall analysis of ZnO indicates strain in the lattice and size is of 20 nm. ? PL shows a broad emission peak in visible range due to native defects. ? Raman active modes corresponding to P6{sub 3}mc and a few additional modes are observed. ? FTIR detects few local vibrational modes of hydrogen attached to zinc vacancies. ? V{sub Zn}-H and Zn + O divacancies are confirmed by PAS. -- Abstract: ZnO being a well known optoelectronic semiconductor, investigations related to the defects are very promising. In this report, we have attempted to detect the defects in ZnO nanoparticles synthesized by the conventional coprecipitation route using various spectroscopic techniques. The broad emission peak observed in photoluminescence spectrum and the non zero slope in Williamson–Hall analysis indicate the defects induced strain in the ZnO lattice. A few additional modes observed in Raman spectrum could be due to the breakdown of the translation symmetry of the lattice caused by defects and/or impurities. The presence of impurities can be ruled out as XRD pattern shows pure wurtzite structure. The presence of the vibrational band related to the Zn vacancies (V{sub Zn}), unintentional hydrogen dopants and their complex defects confirm the defects in ZnO lattice. Positron life time components ?{sub 1} and ?{sub 2} additionally support V{sub Zn} attached to hydrogen and to a cluster of Zn and O di-vacancies respectively.

  1. Comparison of fast 3D simulation and actinic inspection for EUV masks with buries defects

    SciTech Connect (OSTI)

    Clifford, C. H.; Wiraatmadja, S.; Chan, T. T.; Neureuther, A. R.; Goldberg, K. A.; Mochi, I.; Liang, T.

    2009-02-23T23:59:59.000Z

    Aerial images for isolated defects and the interactions of defects with features are compared between the Actinic Inspection Tool (AIT) at Lawrence Berkeley National Laboratory (LBNL) and the fast EUV simulation program RADICAL. Comparisons between AIT images from August 2007 and RADICAL simulations are used to extract aberrations. At this time astigmatism was the dominant aberration with a value of 0.55 waves RMS. Significant improvements in the imaging performance of the AIT were made between August 2007 and December 2008. A good match will be shown between the most recent AIT images and RADICAL simulations without aberrations. These comparisons will demonstrate that a large defect, in this case 7nm tall on the surface, is still printable even if it is centered under the absorber line. These comparisons also suggest that the minimum defect size is between 1.5nm and 0.8nm surface height because a 1.5nm defect was printable but a 0.8nm was not. Finally, the image of a buried defect near an absorber line through focus will demonstrate an inversion in the effect of the defect from a protrusion of the dark line into the space to a protrusion of the space into the line.

  2. Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

    DOE Patents [OSTI]

    Ellingson, W.A.; Brada, M.P.

    1995-06-20T23:59:59.000Z

    A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser`s wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known ``feature masks`` of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects. 29 figs.

  3. Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

    DOE Patents [OSTI]

    Ellingson, William A. (Naperville, IL); Brada, Mark P. (Goleta, CA)

    1995-01-01T23:59:59.000Z

    A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser's wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known "feature masks" of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects.

  4. Screening method for selecting semiconductor substrates having defects below a predetermined level in an oxide layer

    DOE Patents [OSTI]

    Warren, W.L.; Vanheusden, K.J.R.; Schwank, J.R.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.

    1998-07-28T23:59:59.000Z

    A method is disclosed for screening or qualifying semiconductor substrates for integrated circuit fabrication. The method comprises the steps of annealing at least one semiconductor substrate at a first temperature in a defect-activating ambient (e.g. hydrogen, forming gas, or ammonia) for sufficient time for activating any defects within on oxide layer of the substrate; measuring a defect-revealing electrical characteristic of at least a portion of the oxide layer for determining a quantity of activated defects therein; and selecting substrates for which the quantity of activated defects is below a predetermined level. The defect-revealing electrical characteristic may be a capacitance-versus voltage (C-V) characteristic or a current-versus-voltage (I-V) characteristic that is dependent on an electrical charge in the oxide layer generated by the activated defects. Embodiments of the present invention may be applied for screening any type of semiconductor substrate or wafer having an oxide layer formed thereon or therein. This includes silicon-on-insulator substrates formed by a separation by the implantation of oxygen (SIMOX) process or the bond and etch back silicon-on-insulator (BESOI) process, as well as silicon substrates having a thermal oxide layer or a deposited oxide layer. 5 figs.

  5. Sandia Energy - Hydrogen Behavior

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > TheNuclear Press ReleasesInAppliedEnergyGeothermalBehavior Home

  6. 3.40J / 22.71J Physical Metallurgy, Spring 2004

    E-Print Network [OSTI]

    Russell, Kenneth

    This course examines how the presence of 1-, 2- and 3D defects and second phases control the mechanical, electromagnetic and chemical behavior of metals and alloys. It considers point, line and interfacial defects in the ...

  7. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Ju Li Professor MIT Electrochemical-mechanical actions computational and experimental research on mechanical properties of materials, and energy storage and conversion Refreshments served at 10:45 AM The creation of a nanoscale electrochemical and mechanical testing platform

  8. Parity-odd anomalies and correlation functions on conical defects

    E-Print Network [OSTI]

    Cvitan, Maro; Pallua, Silvio; Smoli?, Ivica; Štemberga, Tamara

    2015-01-01T23:59:59.000Z

    We analyse parity-odd ("P-type") surface anomalies ("Graham-Witten anomalies") of energy-momentum correlators in conformal field theories defined in d-dimensional spacetime supplemented with a conical defect, with an emphases on d=4 and d=3 cases. In d=4 we show that the trace anomaly will receive such surface contribution if the bulk trace anomaly contains P-type anomaly given by Pontryagin (pseudo)tensor, and as a consequence 2-point correlation function of energy-momentum tensor in flat spacetime will be nonvanishing as it receives corresponding surface contributions. In the process, we construct the most general P-type surface trace anomaly on singular 2-dimensional surface in 4-dimensional spacetime by performing consistency analysis. We show that there are two independent terms, one is the outer curvature (pseudo)scalar and the other is quadratic in the traceless part of the second fundamental tensor. For the special case of conical singularity we calculate the coefficient of the first term. Though we w...

  9. Control of Suspect/Counterfeit and Defective Items

    SciTech Connect (OSTI)

    Sheriff, Marnelle L.

    2013-09-03T23:59:59.000Z

    This procedure implements portions of the requirements of MSC-MP-599, Quality Assurance Program Description. It establishes the Mission Support Alliance (MSA) practices for minimizing the introduction of and identifying, documenting, dispositioning, reporting, controlling, and disposing of suspect/counterfeit and defective items (S/CIs). employees whose work scope relates to Safety Systems (i.e., Safety Class [SC] or Safety Significant [SS] items), non-safety systems and other applications (i.e., General Service [GS]) where engineering has determined that their use could result in a potential safety hazard. MSA implements an effective Quality Assurance (QA) Program providing a comprehensive network of controls and verification providing defense-in-depth by preventing the introduction of S/CIs through the design, procurement, construction, operation, maintenance, and modification of processes. This procedure focuses on those safety systems, and other systems, including critical load paths of lifting equipment, where the introduction of S/CIs would have the greatest potential for creating unsafe conditions.

  10. Hydrogen decoration of radiation damage induced defect structures

    SciTech Connect (OSTI)

    Kirnstötter, S. [Institute of Solid State Physics, Graz University of Technology, 8010 Graz and Infineon Technologies Austria AG, 9500 Villach (Austria); Faccinelli, M.; Hadley, P. [Institute of Solid State Physics, Graz University of Technology, 8010 (Austria); Schustereder, W. [Infineon Technologies Austria AG, 9500 Villach (Austria); Laven, J. G.; Schulze, H.-J. [Infineon Technologies AG, 81726 Munich (Germany)

    2014-02-21T23:59:59.000Z

    The defect complexes that are formed when protons with energies in the MeV-range were implanted into high-purity silicon were investigated. After implantation, the samples were annealed at 400 °C or 450 °C for times ranging between 15 minutes and 30 hours. The resistivity of the samples was then analyzed by Spreading Resistance Profiling (SRP). The resistivity shows minima where there is a high carrier concentration and it is possible to extract the carrier concentration from the resistivity data. Initially, there is a large peak in the carrier concentration at the implantation depth where most of the hydrogen is concentrated. For longer anneals, this peak widens as the hydrogen diffuses away from the implantation depth. Following the changes in resistivity as a function of annealing time allows us to characterize the diffusion of hydrogen through these samples. Differences in the diffusion were observed depending on whether the silicon was grown by the magnetic Czochralski (m:Cz) method or the Float zone (Fz) method.

  11. The Defect Induced Mix Experiment (DIME) for NIF

    SciTech Connect (OSTI)

    Schmitt, Mark J [Los Alamos National Laboratory; Bradley, Paul A [Los Alamos National Laboratory; Cobble, James A [Los Alamos National Laboratory; Hakel, Peter [Los Alamos National Laboratory; Hsu, Scott C [Los Alamos National Laboratory; Krasheninnikova, Natalia S [Los Alamos National Laboratory; Kyrala, George A [Los Alamos National Laboratory; Murphy, Thomas J [Los Alamos National Laboratory; Obrey, Kimberly A [Los Alamos National Laboratory; Shah, Rahul C [Los Alamos National Laboratory; Tregillis, Ian L [Los Alamos National Laboratory

    2012-06-18T23:59:59.000Z

    LANL will perform two Defect Induced Mix Experiment (DIME) implosion campaigns on NIF in July and September, 2012. This presentation describes the goals for these shots and the experimental configuration and diagnostic set up to collect the appropriate data. The first two-shot campaign will focus on executing polar direct drive (PDD) implosions of plastic CH capsules filled with deuterium gas. Gas filling will be performed through a fill tube at target chamber center. A vanadium backligher foil will provide x-rays to radiograph the last half of the implosion to compare the implosion trajectory with modeling predictions. An equatorial groove in one of the capsules will be present to determine its effect on implosion dynamics. The second DIME campaign will commission and use a spectral imager (MMI) to examine the evolution of thin capsule layers doped with either Ge or Ga at 1.85%. Spectral line emission from these layers will quantify the mix width at the inner shell radius and near an equatorial groove feature.

  12. Current rectification, switching, polarons, and defects in molecular electronic devices

    E-Print Network [OSTI]

    A. M. Bratkovsky

    2006-11-06T23:59:59.000Z

    Devices for nano- and molecular size electronics are currently a focus of research aimed at an efficient current rectification and switching. A few generic molecular scale devices are reviewed here on the basis of first-principles and model approaches. Current rectification by (ballistic) molecular quantum dots can produce the rectification ratio ~100. Current switching due to conformational changes in the molecules is slow, on the order of a few kHz. Fast switching (~1THz) may be achieved, at least in principle, in a degenerate molecular quantum dot with strong coupling of electrons with vibrational excitations. We show that the mean-field approach fails to properly describe intrinsic molecular switching and present an exact solution to the problem. Defects in molecular films result in spurious peaks in conductance, apparent negative differential resistance, and may also lead to unusual temperature and bias dependence of current. The observed switching in many cases is_extrinsic_, caused by changes in molecule-electrode geometry, molecule reconfiguration, metallic filament formation through, and/or changing amount of disorder in a molecular film. We give experimental examples of telegraph "switching" and "hot spot" formation in the molecular films.

  13. Kinetic model for electric-field induced point defect redistribution near semiconductor surfaces

    SciTech Connect (OSTI)

    Gorai, Prashun; Seebauer, Edmund G., E-mail: eseebaue@illinois.edu [Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801 (United States)

    2014-07-14T23:59:59.000Z

    The spatial distribution of point defects near semiconductor surfaces affects the efficiency of devices. Near-surface band bending generates electric fields that influence the spatial redistribution of charged mobile defects that exchange infrequently with the lattice, as recently demonstrated for pile-up of isotopic oxygen near rutile TiO{sub 2} (110). The present work derives a mathematical model to describe such redistribution and establishes its temporal dependence on defect injection rate and band bending. The model shows that band bending of only a few meV induces significant redistribution, and that the direction of the electric field governs formation of either a valley or a pile-up.

  14. The RF performance of cavity made from defective niobium material determined by Eddy Current Scanning

    SciTech Connect (OSTI)

    Wu, G.; Cooley, L.; Sergatskov, D.; Ozelis, J.; /Fermilab; Brinkmann, A.; Singer, W.; Singer, X.; /DESY; Pekeler, M.

    2010-10-01T23:59:59.000Z

    Eddy current scanning (ECS) has been used to screen niobium sheets to avoid defective material being used in costly cavity fabrication. The evaluation criterion of this quality control tool is not well understood. Past surface studies showed some features were shallow enough to be removed by chemical etching. The remaining features were identified to be small number of deeper inclusions, but mostly unidentifiable features (by chemical analysis). A real cavity made of defective niobium material has been tested. The cavity achieved high performance with comparable results to the cavities made from defect free cavities. Temperature mapping could help to define the control standard clearly.

  15. Fusion-bonded epoxy coating defects on weld center line of submerged-arc welded pipe

    SciTech Connect (OSTI)

    Sokol, D.R.; Herndon, C.M. (Tenneco Oil Co., Houston, TX (USA))

    1990-08-01T23:59:59.000Z

    The problem of weld center line coating defects in fusion-bonded epoxy coatings has occurred on pipe produced in Europe, North America, and Asia. At various times, the defects have been attributed to coating application practices, powder manufacturing, pipe manufacturing, welding methods, and overly critical inspectors. This article details plant experience and experimental trails that led to the identification of the cause and proof of the solution. The ultimate effect of initial coating defects on cathodic protection requirements is a matter of concern also.

  16. Scattering of linear and nonlinear waves in a waveguide array with a PT-symmetric defect

    SciTech Connect (OSTI)

    Dmitriev, Sergey V.; Suchkov, Sergey V. [Institute for Metals Superplasticity Problems, Russian Academy of Science, Ufa RU-450001 (Russian Federation); Sukhorukov, Andrey A.; Kivshar, Yuri S. [Nonlinear Physics Centre, Research School of Physics and Engineering,Australian National University, Canberra, ACT 0200 (Australia)

    2011-07-15T23:59:59.000Z

    We study the scattering of linear and nonlinear waves in a long waveguide array with a parity-time (PT)-symmetric defect created by two waveguides with balanced gain and loss. We present exact solutions for the scattering of linear waves on such a defect, and then demonstrate numerically that the linear theory can describe, with a good accuracy, the soliton scattering in the case of weak nonlinearity. We reveal that the reflected and transmitted linear and nonlinear waves can be amplified substantially after interaction with the PT-symmetric defect thus allowing an active control of the wave scattering in the array.

  17. Spin counting in electrically detected magnetic resonance via low-field defect state mixing

    SciTech Connect (OSTI)

    Cochrane, Corey J.; Lenahan, Patrick M. [The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-03-03T23:59:59.000Z

    The work herein describes a method that allows one to measure paramagnetic defect densities in semiconductor and insulator based devices with electrically detected magnetic resonance (EDMR). The method is based upon the mixing of defect states which results from the dipolar coupling of paramagnetic sites at low magnetic fields. We demonstrate the measurement method with spin dependent tunneling in thin film dielectrics; however, the method should be equally applicable to paramagnetic defect density measurements in semiconductors via the more commonly utilized EDMR technique called spin dependent recombination.

  18. Structural defects in GaN revealed by Transmission Electron Microscopy

    SciTech Connect (OSTI)

    Liliental-Weber, Zuzanna

    2014-04-18T23:59:59.000Z

    This paper reviews the various types of structural defects observed by Transmission Electron Microscopy in GaN heteroepitaxial layers grown on foreign substrates and homoepitaxial layers grown on bulk GaN substrates. The structural perfection of these layers is compared to the platelet self-standing crystals grown by High Nitrogen Pressure Solution. Defects in undoped and Mg doped GaN are discussed. Some models explaining the formation of inversion domains in heavily Mg doped layers that are possible defects responsible for the difficulties of p-doping in GaN are also reviewed.

  19. Effect of defects on long-pulse laser-induced damage of two kinds of optical thin films

    SciTech Connect (OSTI)

    Wang Bin; Qin Yuan; Ni Xiaowu; Shen Zhonghua; Lu Jian

    2010-10-10T23:59:59.000Z

    In order to study the effect of defects on the laser-induced damage of different optical thin films, we carried out damage experiments on two kinds of thin films with a 1ms long-pulse laser. Surface-defect and subsurface-defect damage models were used to explain the damage morphology. The two-dimensional finite element method was applied to calculate the temperature and thermal-stress fields of these two films. The results show that damages of the two films are due to surface and subsurface defects, respectively. Furthermore, the different dominant defects for thin films of different structures are discussed.

  20. Mechanics of Electrodes in Lithium-ion Batteries A dissertation presented

    E-Print Network [OSTI]

    #12;Mechanics of Electrodes in Lithium-ion Batteries A dissertation presented by Kejie Zhao, Joost J. Vlassak Kejie Zhao Mechanics of Electrodes in Lithium-ion Batteries Abstract This thesis investigates the mechanical behavior of electrodes in Li-ion batteries. Each electrode in a Li-ion battery