National Library of Energy BETA

Sample records for thermal cracking delayed

  1. Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite

    E-Print Network [OSTI]

    Zok, Frank

    Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite conductances coupled with a unit cell model for a fiber composite containing a periodic array of matrix cracks tolerance and notch insensitivity in continuous fiber ceramic composites (CFCCs).1 These mechanisms play

  2. Thermal resistance of bridged cracks in fiber-reinforced ceramic John Dryden

    E-Print Network [OSTI]

    Zok, Frank

    -reinforced ceramic composites obtain high toughness is through the de- velopment of multiple matrix cracksThermal resistance of bridged cracks in fiber-reinforced ceramic composites John Dryden Department in a fiber-reinforced ceramic composite is analyzed. The problem is cast in terms of a unit cell comprising

  3. Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction of Sand

    E-Print Network [OSTI]

    Michalowski, Radoslaw L.

    of Sand R.L. Michalowski1 , F. ASCE and S. S. Nadukuru2 , Student Member, ASCE 1 University of Michigan Engineering, Ann Arbor, MI 48109-2125, U.S.A.; siddu@umich.edu ABSTRACT Dynamically compacted sands exhibit on the process of stress corrosion cracking of the micro-morphological features on the surface of the sand grains

  4. Efficient blue organic light-emitting diodes employing thermally activated delayed

    E-Print Network [OSTI]

    Cai, Long

    Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence,2 * Organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) have energy is high enough and the 3 LE state is higher than the 3 CT state. O rganic light-emitting diodes

  5. Roles of grain boundaries in cleavage cracking and thermal crack arrest experiments in iron-silicon alloy

    E-Print Network [OSTI]

    Qiao, Yu, 1972-

    2002-01-01

    High-angle grain boundaries in steel offer an important resistance to the propagation of cleavage cracks that affects the fracture toughness and can modulate the ductile-to-brittle transition temperature of fracture downward. ...

  6. Materials Science and Engineering A 490 (2008) 2635 Mechanisms of cracking and delamination within thick thermal barrier

    E-Print Network [OSTI]

    Hutchinson, John W.

    2008-01-01

    that characterizes the susceptibility to delamination of thermal barrier coated (TBC) hot-section aero-turbine. Introduction The maximum temperature capability of thermal barrier systems used in gas turbines is oftenMaterials Science and Engineering A 490 (2008) 26­35 Mechanisms of cracking and delamination within

  7. Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale

    E-Print Network [OSTI]

    Shawabkeh, Reyad A.

    by the thermal cracking process of the El-Lujjan oil shale showed that the yield of oil was around 12 wt of the boiling point for different distillate fractions. Sulfur in Jordanian oil shale was found to be mainly the dominant phases in these fractions. q 2005 Published by Elsevier Ltd. 1. Introduction Oil shale

  8. Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix landing site: Implications for substrate

    E-Print Network [OSTI]

    Marchant, David R.

    Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix within the NASA Phoenix landing site Area D characterized by boulder-topped, polygonally-patterned mounds of buried ice. On the basis of morphological similarities, we classify the Phoenix Box 1 polygons

  9. WATTS TOWERS: THE EFFECTS OF THERMAL CYCLES ON THE FORMATION AND BEHAVIOR OF CRACKS 

    E-Print Network [OSTI]

    Spencer, Matthew T

    2013-02-06

    of cracks located at different sections on the Towers was outfitted with strain gauges, force transducers, and thermocouples to collect data on the crack width as a function of the ambient temperature. Using the Finite Element Analysis program LS-DYNA, a...

  10. Effects of thermal aging on Stress Corrosion Cracking and mechanical properties of stainless steel weld metals

    E-Print Network [OSTI]

    Hixon, Jeff

    2006-01-01

    Stress Corrosion Cracking (SCC) in and around primary loop piping welds in Boiling Water Reactors has been observed worldwide as plants continue to operate at temperatures and pressures near 2880C (5500F) and 6.9 MPa (1000 ...

  11. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence

    SciTech Connect (OSTI)

    Nishide, Jun-ichi; Hiraga, Yasuhide; Nakanotani, Hajime; Adachi, Chihaya

    2014-06-09

    White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

  12. Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter

    SciTech Connect (OSTI)

    Niwa, Akitsugu; Kobayashi, Takashi Nagase, Takashi; Naito, Hiroyoshi; Goushi, Kenichi; Adachi, Chihaya

    2014-05-26

    Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100?K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process.

  13. Hydrocarbon cracking

    SciTech Connect (OSTI)

    McCoy, R.D.

    1980-12-02

    A cracking reactor is controlled in response to the proportion of heavy aromatic constituents in a feedstock to be cracked.

  14. Non-thermal gamma-ray emission from delayed pair breakdown in a magnetized and photon-rich outflow

    SciTech Connect (OSTI)

    Gill, Ramandeep; Thompson, Christopher, E-mail: rgill@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

    2014-12-01

    We consider delayed, volumetric heating in a magnetized outflow that has broken out of a confining medium and expanded to a high Lorentz factor (? ? 10{sup 2}-10{sup 3}) and low optical depth to scattering (? {sub T} ? 10{sup –3}-10{sup –2}). The energy flux at breakout is dominated by the magnetic field, with a modest contribution from quasi-thermal gamma rays whose spectrum was calculated in Paper I. We focus on the case of extreme baryon depletion in the magnetized material, but allow for a separate baryonic component that is entrained from a confining medium. Dissipation is driven by relativistic motion between these two components, which develops once the photon compactness drops below 4 × 10{sup 3}(Y{sub e} /0.5){sup –1}. We first calculate the acceleration of the magnetized component following breakout, showing that embedded MHD turbulence provides significant inertia, the neglect of which leads to unrealistically high estimates of flow Lorentz factor. After reheating begins, the pair and photon distributions are evolved self-consistently using a one-zone kinetic code that incorporates an exact treatment of Compton scattering, pair production and annihilation, and Coulomb scattering. Heating leads to a surge in pair creation, and the scattering depth saturates at ? {sub T} ? 1-4. The plasma maintains a very low ratio of particle to magnetic pressure, and can support strong anisotropy in the charged particle distribution, with cooling dominated by Compton scattering. High-energy power-law spectra with photon indices in the range observed in gamma-ray bursts (GRBs; –3 < ? < –3/2) are obtained by varying the ratio of heat input to the seed energy in quasi-thermal photons. We contrast our results with those for continuous heating across an expanding photosphere, and show that the latter model produces soft-to-hard evolution that is inconsistent with observations of GRBs.

  15. Crack detection using pulsed eddy current stimulated thermography

    SciTech Connect (OSTI)

    Kostson, E.; Weekes, B.; Almond, D. P. [RCNDE, Department of Mechanical Engineering, University of Bath (United Kingdom); Wilson, J.; Tian, G. Y. [School of Electrical, Electronic and Computer Engineering, Newcastle University (United Kingdom)

    2011-06-23

    This contribution presents results from studies investigating factors that influence the detection of surface breaking cracks using pulsed eddy current thermography. The influences of the current strength and crack orientation in both ferromagnetic and non-ferromagnetic metals have been investigated. It has been found that crack detection is far more sensitive to crack orientation in non-ferromagnetic metals than in ferromagnetic metals. The effects of crack size on detectability are presented for a large number of steel, nickel alloy and titanium samples. Results of studies comparing crack images obtained prior and after coating a nickel alloy sample with a thermal barrier coating are presented.

  16. Investigation of Cracked Lithium Hydride Reactor Vessels

    SciTech Connect (OSTI)

    bird, e.l.; mustaleski, t.m.

    1999-06-01

    Visual examination of lithium hydride reactor vessels revealed cracks that were adjacent to welds, most of which were circumferentially located in the bottom portion of the vessels. Sections were cut from the vessels containing these cracks and examined by use of the metallograph, scanning electron microscope, and microprobe to determine the cause of cracking. Most of the cracks originated on the outer surface just outside the weld fusion line in the base material and propagated along grain boundaries. Crack depths of those examined sections ranged from {approximately}300 to 500 {micro}m. Other cracks were reported to have reached a maximum depth of 1/8 in. The primary cause of cracking was the creation of high tensile stresses associated with the differences in the coefficients of thermal expansion between the filler metal and the base metal during operation of the vessel in a thermally cyclic environment. This failure mechanism could be described as creep-type fatigue, whereby crack propagation may have been aided by the presence of brittle chromium carbides along the grain boundaries, which indicates a slightly sensitized microstructure.

  17. Vehicle barrier with access delay

    DOE Patents [OSTI]

    Swahlan, David J; Wilke, Jason

    2013-09-03

    An access delay vehicle barrier for stopping unauthorized entry into secure areas by a vehicle ramming attack includes access delay features for preventing and/or delaying an adversary from defeating or compromising the barrier. A horizontally deployed barrier member can include an exterior steel casing, an interior steel reinforcing member and access delay members disposed within the casing and between the casing and the interior reinforcing member. Access delay members can include wooden structural lumber, concrete and/or polymeric members that in combination with the exterior casing and interior reinforcing member act cooperatively to impair an adversarial attach by thermal, mechanical and/or explosive tools.

  18. Shadows and Cracks

    E-Print Network [OSTI]

    Dowson, Mark

    The VIRGIN program will interpret pictures of crack and shadow free scenes by labelling them according to the Clowes/Huffman formalism. This paper indicates methods of extending the program to include cracks and shadows ...

  19. Crack coalescence in granite

    E-Print Network [OSTI]

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

    2008-01-01

    This thesis experimentally investigates crack coalescence in prismatic Barre Granite specimens with two pre-cut, open flaws under uniaxial compression. Using a high-speed video system, crack initiation, propagation, and ...

  20. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T.

    1997-04-01

    The modification of a computer code for leak before break analysis is very briefly described. The CASTEM2000 code was developed for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading. The modification extends the capabilities of the cracked pipe element to the determination of fracture parameters under creep conditions (C*, {phi}c and {Delta}c). The model has the advantage of evaluating significant secondary effects, such as those from thermal loading.

  1. The relationship between crack-tip strain and subcritical cracking...

    Office of Scientific and Technical Information (OSTI)

    crack-tip strain and subcritical cracking thresholds for steels in high-pressure hydrogen gas. Citation Details In-Document Search Title: The relationship between crack-tip...

  2. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T. [C.E.A.-C.E.-Saclay DRN/DMT, Gif Sur Yvette (France); Ghoudi, M. [C.E.A.-C.E.-Saclay, Gif Sur Yvette (France)

    1997-04-01

    Modifications to a computer code for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading are very briefly described. The modifications extend the capabilities of the CASTEM2000 code to the determination of fracture parameters under creep conditions. The main advantage of the approach is that thermal loads can be evaluated as secondary stresses. The code is applicable to piping systems for which crack propagation predictions differ significantly depending on whether thermal stresses are considered as primary or secondary stresses.

  3. Effect of CTE on Fatigue Cracking of Stainless Steel Vessels

    SciTech Connect (OSTI)

    Bird, E. L.; Mustaleski, T. M.

    2002-01-31

    Visual examination of lithium hydride reactor vessels revealed cracks that were adjacent to welds. Most cracks were parallel to the weld in the bottom portion of the vessel. Sections were cut out of the vessel containing these cracks and examined using the metallograph, scanning electron microscope, and microprobe to determine the cause of cracking. most of the cracks originated on the outer surface just outside the weld fusion line in the heat affected zone and propagated along grain boundaries. Crack depth of those sections examined ranged from about 300 to 500 {micro}m. Other cracks were reported to have reached a maximum depth of 0.32-cm (0.125-inch). The primary cause of cracking was the creation of high tensile stresses associated with the CTE differences between the filler metal and the base metal during operation of the vessel in a thermally cyclic environment. This failure mechanism could be described as creep-type fatigue whereby crack propagation might have been aided by the presence of brittle chromium carbides along the grain boundaries, which is indicative of a slightly sensitized microstructure.

  4. Catalytic cracking process

    SciTech Connect (OSTI)

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  5. Fatigue cracking in materials with brittle surface coatings

    SciTech Connect (OSTI)

    Suresh, S.; Sugimura, Y.; Ogawa, T. (Brown Univ., Providence, RI (United States))

    1993-07-15

    Ceramic coatings enhance the resistance of metal alloys to wear, oxidation, thermal exposure, corrosion, erosion and delamination in a variety of structural, optical, electrical , electronic and bioengineering applications. Recent experimental work on steel-steel bimaterials has shown that the conditions for the growth or arrest of a fatigue crack, which approaches the interface between the two steels perpendicularly, are determined by whether the crack propagates to the interface from the weaker or the stronger material. Specifically, it is found that as the fatigue crack advances toward the interface from the weaker steel, the interaction of the crack-tip plastic zone with the interface results in the arrest of the crack. However, when the fatigue crack is propagated from the stronger to the weaker steel, crack growth occurs unimpeded through the interface. In this paper, the authors present additional experimental and mechanistic descriptions of fatigue crack growth normal to interfaces. They then apply the mechanisms underlying these experiments to the design of fatigue-resistant surface coatings for alloys. In particular, they demonstrate experimentally that a fatigue crack emanating from the brittle outercoating and advancing into the substrate can be arrested and/or deflected by proper choices of ductile interlayers. Experimental results of fatigue crack profiles and high-cycle fatigue lives are presented for two different coated materials: a steel coated with a Cr[sub 2]O[sub 3] layer and a steel coated with a Cr[sub 2]O[sub 3] outerlayer and a soft Ni-Al interlayer. The paper also includes a brief discussion of the application of proposed concepts to nitrided titanium alloys.

  6. Blunt-crack band propagation in finite-element analysis for concrete structures. [LMFBR

    SciTech Connect (OSTI)

    Pfeiffer, P.A.; Bazant, Z.P.; Marchertas, A.H.

    1983-01-01

    The knowledge of concrete fracture is needed in nuclear reactor safety. The question of safety arises from the potential of concrete to crack under thermal loading. It has been postulated that structural concrete could be exposed to very high temperature, which may result from hot reactor coolant or even core debris coming in direct contact with the concrete. The utilization of the blunt crack approach for simulating concrete cracking in a general-purpose code is explored. The difficulties encountered in establishing the proper direction of crack propagation in an arbitrary discretization are described. Crack propagation is considered within the context of two types of solution techniques: (1) implicit solution of the static crack advance, and (2) explicit time integration using a dynamic relaxation technique to simulate the static crack advance. Also, in both solution techniques an elastic model is used to characterize the concrete.

  7. Analytical applications for delayed neutrons

    SciTech Connect (OSTI)

    Eccleston, G.W.

    1983-01-01

    Analytical formulations that describe the time dependence of neutron populations in nuclear materials contain delayed-neutron dependent terms. These terms are important because the delayed neutrons, even though their yields in fission are small, permit control of the fission chain reaction process. Analytical applications that use delayed neutrons range from simple problems that can be solved with the point reactor kinetics equations to complex problems that can only be solved with large codes that couple fluid calculations with the neutron dynamics. Reactor safety codes, such as SIMMER, model transients of the entire reactor core using coupled space-time neutronics and comprehensive thermal-fluid dynamics. Nondestructive delayed-neutron assay instruments are designed and modeled using a three-dimensional continuous-energy Monte Carlo code. Calculations on high-burnup spent fuels and other materials that contain a mix of uranium and plutonium isotopes require accurate and complete information on the delayed-neutron periods, yields, and energy spectra. A continuing need exists for delayed-neutron parameters for all the fissioning isotopes.

  8. Grain-by-grain study of the mechanisms of crack propagation during iodine stress corrosion cracking of Zircaloy-4

    SciTech Connect (OSTI)

    Haddad, R.E. [CNEA, Buenos Aires (Argentina); Dorado, A.O. [CONICET, Buenos Aires (Argentina)

    1994-12-31

    This paper describes the tests conducted to determine the conditions leading to cracking of a specified grain of metal, during the iodine stress corrosion cracking (SCC) of zirconium alloys, focusing on the crystallographic orientation of crack paths, the critical stress conditions, and the significance of the fractographic features encountered. In order to perform crystalline orientation of fracture surfaces, a specially heat-treated Zircaloy-4 having very large grains, grown up to the wall thickness, was used. Careful orientation work has proved that intracrystalline pseudo-cleavage occurs only along basal planes. the effects of anisotropy, plasticity, triaxiality, and residual stresses originated in thermal contraction have to be considered to account for the influence of the stress state. A grain-by-grain calculation led to the conclusion that transgranular cracking always takes place on those bearing the maximum resolved tensile stress perpendicular to basal planes. Propagation along twin boundaries has been identified among the different fracture modes encountered.

  9. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect (OSTI)

    Saha, Dulal Chandra [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Chang, InSung [Automotive Production Development Division, Hyundai Motor Company (Korea, Republic of); Park, Yeong-Do, E-mail: ypark@deu.ac.kr [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  10. Cracks in Martensite Plates as Hydrogen Traps in a Bearing Steel

    E-Print Network [OSTI]

    Solano-Alvarez, W.; Song, Eun Ju; Han, Do Kyeong; Suh, Dong-Woo; Bhadeshia, H. K. D. H.

    2014-12-03

    It is demonstrated that a macroscopically homogeneous distribution of tiny cracks introduced into a martensitic bearing steel sample can provide powerful hydrogen traps. The phenomenon has been investigated through thermal desorption spectroscopy...

  11. Crack-resistant siloxane molding compounds. [Patent application

    DOE Patents [OSTI]

    McFarland, J.W.; Swearngin, C.B.

    1980-11-03

    The crack resistance of phenyl silicone molding resins containing siliceous fillers is improved by incorporating therein about 0.5 to 5.5% by weight of ..beta..-eucryptite, a lithium aluminum silicate having a negative thermal expansion coefficient. These molding resins are particularly suitable for encapsulating electronic devices such as diodes, coils, resistors, and the like.

  12. Flexible Macroscopic Models for Dense-Fluid Shockwaves: Partitioning Heat and Work; Delaying Stress and Heat Flux; Two-Temperature Thermal Relaxation

    E-Print Network [OSTI]

    Wm. G. Hoover; Carol G. Hoover; Francisco J. Uribe

    2010-05-10

    Macroscopic models which distinguish the longitudinal and transverse temperatures can provide improved descriptions of the microscopic shock structures as revealed by molecular dynamics simulations. Additionally, we can include three relaxation times in the models, two based on Maxwell's viscoelasticity and its Cattaneo-equation analog for heat flow, and a third thermal, based on the Krook-Boltzmann equation. This approach can replicate the observed lags of stress (which lags behind the strain rate) and heat flux (which lags behind the temperature gradient), as well as the eventual equilibration of the two temperatures. For profile stability the time lags cannot be too large. By partitioning the longitudinal and transverse contributions of work and heat and including a tensor heat conductivity and bulk viscosity, all the qualitative microscopic features of strong simple-fluid shockwave structures can be reproduced.

  13. Thermally activated delayed fluorescence from {sup 3}n?* to {sup 1}n?* up-conversion and its application to organic light-emitting diodes

    SciTech Connect (OSTI)

    Li, Jie; Zhang, Qisheng; Nomura, Hiroko [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Miyazaki, Hiroshi [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Functional Materials Laboratory, Nippon Steel and Sumikin Chemical Co., Ltd, 46–80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804–8503 (Japan); Adachi, Chihaya, E-mail: adachi@cstf.kyushu-u.ac.jp [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2014-07-07

    Intense n?* fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the n?* transition and the higher energy of the {sup 3}??* state than the {sup 3}n?* one lead to a small energy difference between the lowest singlet (S{sub 1}) and triplet (T{sub 1}) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T{sub 1} ? S{sub 1} pathway in the electroluminescent process.

  14. Stress corrosion crack growth in porous sandstones. 

    E-Print Network [OSTI]

    Ojala, Ira O

    Stress corrosion crack growth occurs when the chemical weakening of strained crack tip bonds facilitates crack propagation. I have examined the effect of chemical processes on the growth of a creack population by carrying out triaxial compression...

  15. Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617

    SciTech Connect (OSTI)

    Ma, Longzhou

    2012-11-30

    The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or SAGBOE damage process under hold-time fatigue and sustained loading conditions

  16. Investigation of the "summation" method for predicting group dependent delayed neutron data 

    E-Print Network [OSTI]

    Angers, Laetitia Genevieve

    1998-01-01

    of the average delayed neutron lifetime by 15% for U-235 thermal fission, which agrees more closely with Keepin's results. The modified delayed neutron data set also improves the calculated reactor period (relative to the reactor period calculated using Keepin...

  17. Peridynamic model for fatigue cracking.

    SciTech Connect (OSTI)

    Silling, Stewart A.; Abe Askari

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the %22remaining life%22 of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  18. Discrete Element Model for Simulations of Early-Life Thermal Fracturing Behaviors in Ceramic Nuclear Fuel Pellets

    SciTech Connect (OSTI)

    Hai Huang; Ben Spencer; Jason Hales

    2014-10-01

    A discrete element Model (DEM) representation of coupled solid mechanics/fracturing and heat conduction processes has been developed and applied to explicitly simulate the random initiations and subsequent propagations of interacting thermal cracks in a ceramic nuclear fuel pellet during initial rise to power and during power cycles. The DEM model clearly predicts realistic early-life crack patterns including both radial cracks and circumferential cracks. Simulation results clearly demonstrate the formation of radial cracks during the initial power rise, and formation of circumferential cracks as the power is ramped down. In these simulations, additional early-life power cycles do not lead to the formation of new thermal cracks. They do, however clearly indicate changes in the apertures of thermal cracks during later power cycles due to thermal expansion and shrinkage. The number of radial cracks increases with increasing power, which is consistent with the experimental observations.

  19. Time delay in photoemission by attosecond laser pulses

    E-Print Network [OSTI]

    J. Marciak-Kozlowska; M. Kozlowski

    2013-02-15

    Recently the time delay in the attosecond photoemission was observed (Science,2010). In this paper we propose the description of that time delay in the framework of hyperbolic heat transport equation. We argue that the observed time delay 20 as is of the order of the thermal relaxation time for hyperbolic quantum heat transport. As the generalization of the standard quantum mechanics we propose new local Schroedinger equation with c=finite

  20. Thermal Shock-resistant Cement

    SciTech Connect (OSTI)

    Sugama T.; Pyatina, T.; Gill, S.

    2012-02-01

    We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved cement, causing its volume to expand.

  1. Nonlinear structural crack growth monitoring

    DOE Patents [OSTI]

    Welch, Donald E. (Oak Ridge, TN); Hively, Lee M. (Philadelphia, TN); Holdaway, Ray F. (Clinton, TN)

    2002-01-01

    A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

  2. Degradation of Structural Alloys Under Thermal Insulation 

    E-Print Network [OSTI]

    McIntyre, D. R.

    1984-01-01

    Wet thermal insulation may actively degrade steel and stainless steel structures by general corrosion or stress-corrosion cracking. Two different mechanisms of water ingress into insulation are discussed; flooding from external sources...

  3. Cracking in reinforced concrete bent caps 

    E-Print Network [OSTI]

    Young, Bradley S.

    2000-01-01

    cracking in order to improve durability and reduce maintenance costs of bent caps throughout the lifetime of the structure. Excessive cracking in RC bent caps can be controlled through improved design detailing for both flexure and shear. For flexure...

  4. Digital time delay

    DOE Patents [OSTI]

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay provides a first output signal at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits latch the high resolution data to form a first synchronizing data set. A selected time interval has been preset to internal counters and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses count down the counters to generate an internal pulse delayed by an internal which is functionally related to the preset time interval. A second LCD corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD to generate a second set of synchronizing data which is complementary with the first set of synchronizing data for presentation to logic circuits. The logic circuits further delay the internal output signal with the internal pulses. The final delayed output signal thereafter enables the output pulse generator to produce the desired output pulse at the preset time delay interval following input of the trigger pulse.

  5. Prediction of crack propagation paths in the unit cell of SOFC stacks

    SciTech Connect (OSTI)

    Joulaee, N.; Makradi, A.; Ahzi, Said; Khaleel, Mohammad A.; Koeppel, Brian J.

    2009-08-01

    Planar Solid Oxide Fuel Cells (SOFC) stacks are multi-material layered systems with different thermo-mechanical properties. Due to their severe thermal loading, these layers have to meet high demands to preserve their mechanical integrity without initiation and propagation of fracture. Here, we focus on a typical unit cell of the stack which consists of positive electrode-electrolyte-negative electrode (PEN). Based on the mechanical properties of each layer and their interfaces, an energy criterion as a function of crack length is used for the prediction of possible crack extensions in the PEN. This criterion is a pure local criterion, independent of applied loads and geometry of the specimen. An analysis of the competition between crack deflections in the interfaces and crack penetration in layers is presented.

  6. Fundamentals of Delayed Coking Joint Industry Project

    SciTech Connect (OSTI)

    Michael Volk; Keith Wisecarver

    2004-09-26

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking.

  7. Fundamentals of Delayed Coking Joint Industry Project

    SciTech Connect (OSTI)

    Michael Volk; Keith Wisecarver

    2003-09-26

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking.

  8. Downhole delay assembly for blasting with series delay

    DOE Patents [OSTI]

    Ricketts, Thomas E. (Grand Junction, CO)

    1982-01-01

    A downhole delay assembly is provided which can be placed into a blasthole for initiation of explosive in the blasthole. The downhole delay assembly includes at least two detonating time delay devices in series in order to effect a time delay of longer than about 200 milliseconds in a round of explosions. The downhole delay assembly provides a protective housing to prevent detonation of explosive in the blasthole in response to the detonation of the first detonating time delay device. There is further provided a connection between the first and second time delay devices. The connection is responsive to the detonation of the first detonating time delay device and initiates the second detonating time delay device. A plurality of such downhole delay assemblies are placed downhole in unfragmented formation and are initiated simultaneously for providing a round of explosive expansions. The explosive expansions can be used to form an in situ oil shale retort containing a fragmented permeable mass of formation particles.

  9. The influence of cracks in rotating shafts

    E-Print Network [OSTI]

    Sinou, Jean-Jacques

    2008-01-01

    In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

  10. The influence of cracks in rotating shafts

    E-Print Network [OSTI]

    Jean-Jacques Sinou; A. W. Lees

    2008-01-19

    In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

  11. Materials Science and Engineering A 404 (2005) 2632 Numerical simulations of crack formation from pegs in

    E-Print Network [OSTI]

    Fleck, Norman A.

    2005-01-01

    in gas turbines for propulsion and power generation [1­4]. The systems are susceptible to performanceMaterials Science and Engineering A 404 (2005) 26­32 Numerical simulations of crack formation from pegs in thermal barrier systems with NiCoCrAlY bond coats H.X. Zhua, N.A. Flecka,, A.C.F. Cocksb, A

  12. Characterization of geothermal reservoir crack patterns using...

    Open Energy Info (EERE)

    with form History Characterization of geothermal reservoir crack patterns using shear-wave splitting Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal...

  13. Crack stability analysis of low alloy steel primary coolant pipe

    SciTech Connect (OSTI)

    Tanaka, T.; Kameyama, M. [Kansai Electric Power Company, Osaka (Japan); Urabe, Y. [Mitsubishi Heavy Industries, Ltd., Takasago (Japan)] [and others

    1997-04-01

    At present, cast duplex stainless steel has been used for the primary coolant piping of PWRs in Japan and joints of dissimilar material have been applied for welding to reactor vessels and steam generators. For the primary coolant piping of the next APWR plants, application of low alloy steel that results in designing main loops with the same material is being studied. It means that there is no need to weld low alloy steel with stainless steel and that makes it possible to reduce the welding length. Attenuation of Ultra Sonic Wave Intensity is lower for low alloy steel than for stainless steel and they have advantageous inspection characteristics. In addition to that, the thermal expansion rate is smaller for low alloy steel than for stainless steel. In consideration of the above features of low alloy steel, the overall reliability of primary coolant piping is expected to be improved. Therefore, for the evaluation of crack stability of low alloy steel piping to be applied for primary loops, elastic-plastic future mechanics analysis was performed by means of a three-dimensioned FEM. The evaluation results for the low alloy steel pipings show that cracks will not grow into unstable fractures under maximum design load conditions, even when such a circumferential crack is assumed to be 6 times the size of the wall thickness.

  14. Delayed coking of decant oil and coal in a laboratory-scale coking unit

    SciTech Connect (OSTI)

    Oemer Guel; Leslie R. Rudnick; Harold H. Schobert [Pennsylvania State University Park, PA (United States). Energy Institute, C205 Coal Utilization Laboratory

    2006-08-15

    In this paper, we describe the development of a laboratory-scale delayed coker and present results of an investigation on the recovered liquid from the coking of decant oil and decant oil/coal mixtures. Using quantitative gas chromatography/mass spectroscopy (GC/MS) and {sup 1}H and {sup 13}C NMR, a study was made of the chemical composition of the distillate liquids isolated from the overheads collected during the coking and co-coking process. {sup 1}H and {sup 13}C NMR analyses of combined liquids from coking and co-coking did not show any substantial differences. These NMR results of coking and co-coking liquids agree with those of GC/MS. In these studies, it was observed that co-coking with coal resulted in a decrease in the paraffins contents of the liquid. The percentage of cycloparaffins, indenes, naphthalenes, and tetralins did not change significantly. In contrast, alkyl benzenes and polycyclic aromatic hydrocarbons in the distillate were higher in the co-coking experiments which may have resulted from the distillation of thermally cracked coal macromolecules and the contribution of these molecules to the overall liquid composition. 40 refs., 3 figs., 13 tabs.

  15. On Macroscopic and MicroscopicAnalyses for Crack Initiationand Crack Growth Toughness in DuctileAlloys

    E-Print Network [OSTI]

    Ritchie, Robert

    On Macroscopic and MicroscopicAnalyses for Crack Initiationand Crack Growth Toughness in Ductile microvoid coalescence, expressions are shown for the fracture toughness of materials in terms and the nondimensionalized crack initiation fracture toughness Ji~ is described and shown to yield a good fit to experimental

  16. Study on grain boundary character and strain distribution of intergranular cracking in the CGHAZ of T23 steel

    SciTech Connect (OSTI)

    Jin, Y.J.; Lu, H., E-mail: shweld@sjtu.edu.cn; Yu, C.; Xu, J.J.

    2013-10-15

    Intergranular reheat cracking in the coarse-grained heat-affected zone of T23 steel was produced by strain to fracture tests on a Gleeble 3500 thermal–mechanical simulator. Then the grain boundary character, as well as the strain distribution after reheat crack propagation, was studied by electron backscatter diffraction technique. The results showed that incoherent ?3 boundaries were seldom found on the prior austenite grain boundaries. Therefore, only the type of random high-angle boundaries played a crucial role in the intergranular cracking. Microstructurally cavities and small cracks were preferentially initiated from high-angle grain boundaries. Low-angle grain boundaries and high-angle ones with misorientation angles less than 15° were more resistant to the cracking. More importantly, the fraction of high-angle grain boundaries increased with the plastic strain induced by both temperature gradient and stress in the coarse-grained heat-affected zone, which contributed to the crack initiation and propagation. Furthermore, the strain distributions in the vicinity of cavities and cracks revealed the accommodation processes of plastic deformation during stress relaxation. It also reflected the strength differences between grain interior and grain boundary at different heat-treated temperatures, which had a large influence on the cracking mechanism. - Highlights: • The coincidence site lattice boundaries play little role in the reheat cracking. • Cavity and crack occur at high-angle grain boundaries rather than low-angle ones. • The strain leads low-angle grain boundaries to transform to high-angle ones. • Strain distribution differs for cavity and crack zones at different temperatures.

  17. Characterization of Fatigue Cracking and Healing of Asphalt Mixtures 

    E-Print Network [OSTI]

    Luo, Xue

    2012-07-16

    Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing ...

  18. Constraint effects observed in crack initiation stretch

    SciTech Connect (OSTI)

    Lambert, D.M.; Ernst, H.A.

    1995-12-31

    The current paper characterizes constraint in fracture: J-modified resistance (Jr) curves were developed for two tough structural materials, 6061-T651 (aluminum) and IN718-STA1 (nickel-base superalloy). A wide variety of configurations was tested to consider load configurations from bending to tension including three specimen types (compact tension, center-crack tension, and single-edge notched tension), and a range of ligament lengths and thicknesses, as well as side-grooved and smooth-sided ligaments. The Jr curves exhibited an inflection point after some crack extension, and the data were excluded beyond the inflection. Qualified Jr curves for the two materials showed similar behavior, but R-curves were identical for equal ligament length-to-thickness ratio (RL), for the aluminum alloy, with increasing slope for increasing RL, while for the nickel, the resistance curves aligned for equal ligament thickness, B, and the slope increased for decreasing B. Displacements at the original crack tip (CToD) were recorded throughout the test for several specimens. CToD-versus-crack extension curves were developed, and data were excluded beyond the inflection point (as with the Jr curves). The data collapsed into two distinct curves, thought to represent the surface, plane stress effect and the central, plane strain effect. This was observed for both materials. A technique called profiling is presented for the aluminum alloy only, where the crack face displacements are recorded at the final point of the test as a function of the position throughout the crack cavity, along with an effort to extract the observations in a usable form. Displacements were consistent throughout the cross-section at and behind the original crack tip. In the region where the crack grew, this displacement was developed by a combination of stretch and crack growth. The stretch required to initiate crack extension was a function of the depth beneath the surface into the cross-section.

  19. Congestion delays at hub airports

    E-Print Network [OSTI]

    St. George, Martin J.

    1986-01-01

    A deterministic model was developed to study the effects of inefficient scheduling on flight delays at hub airports. The model bases the delay calculation on published schedule data and on user-defined airport capacities. ...

  20. Prediction of thermal crack spacing D.H. Timm a

    E-Print Network [OSTI]

    Guzina, Bojan

    of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. S.E., Minneapolis, MN 55455, USA Received cooling event in the winter of 1996 when the surface pavement temperature dropped below )30 °C

  1. Programmable Differential Delay Circuit With Fine Delay Adjustment

    DOE Patents [OSTI]

    DeRyckere, John F. (Eau Claire, WI); Jenkins, Philip Nord (Eau Claire, WI); Cornett, Frank Nolan (Chippewa Falls, WI)

    2002-07-09

    Circuitry that provides additional delay to early arriving signals such that all data signals arrive at a receiving latch with same path delay. The delay of a forwarded clock reference is also controlled such that the capturing clock edge will be optimally positioned near quadrature (depending on latch setup/hold requirements). The circuitry continuously adapts to data and clock path delay changes and digital filtering of phase measurements reduce errors brought on by jittering data edges. The circuitry utilizes only the minimum amount of delay necessary to achieve objective thereby limiting any unintended jitter. Particularly, this programmable differential delay circuit with fine delay adjustment is designed to allow the skew between ASICS to be minimized. This includes skew between data bits, between data bits and clocks as well as minimizing the overall skew in a channel between ASICS.

  2. Cracked-fuel mechanics. [PWR; BWR

    SciTech Connect (OSTI)

    Williford, R.E.; Lanning, D.D.

    1982-01-01

    This paper presents a modelling concept and a set of measurable parameters that have been shown to improve the prediction of the mechanical behavior of cracked fuel/cladding systems without added computational expense. The transition from classical annular gap/cylindrical pellet models to modified bulk properties and further to local behavior for cracked fuel systems is discussed. The results of laboratory experiments to verify these modelling parameters are shown. Data are also presented from laboratory experiments on unirradiated and irradiated rods which show that fuel rod mechanical response depends on fuel fragment size. The impact of these data on cracked fuel behavior and failure modelling is also discussed.

  3. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels in BWR Environments

    SciTech Connect (OSTI)

    Chen, Y.; Chopra, O. K.; Gruber, Eugene E.; Shack, William J.

    2010-06-01

    The internal components of light water reactors are exposed to high-energy neutron irradiation and high-temperature reactor coolant. The exposure to neutron irradiation increases the susceptibility of austenitic stainless steels (SSs) to stress corrosion cracking (SCC) because of the elevated corrosion potential of the reactor coolant and the introduction of new embrittlement mechanisms through radiation damage. Various nonsensitized SSs and nickel alloys have been found to be prone to intergranular cracking after extended neutron exposure. Such cracks have been seen in a number of internal components in boiling water reactors (BWRs). The elevated susceptibility to SCC in irradiated materials, commonly referred to as irradiation-assisted stress corrosion cracking (IASCC), is a complex phenomenon that involves simultaneous actions of irradiation, stress, and corrosion. In recent years, as nuclear power plants have aged and irradiation dose increased, IASCC has become an increasingly important issue. Post-irradiation crack growth rate and fracture toughness tests have been performed to provide data and technical support for the NRC to address various issues related to aging degradation of reactor-core internal structures and components. This report summarizes the results of the last group of tests on compact tension specimens from the Halden-II irradiation. The IASCC susceptibility of austenitic SSs and heat-affected-zone (HAZ) materials sectioned from submerged arc and shielded metal arc welds was evaluated by conducting crack growth rate and fracture toughness tests in a simulated BWR environment. The fracture and cracking behavior of HAZ materials, thermally sensitized SSs and grain-boundary engineered SSs was investigated at several doses (?3 dpa). These latest results were combined with previous results from Halden-I and II irradiations to analyze the effects of neutron dose, water chemistry, alloy compositions, and welding and processing conditions on IASCC. The effect of neutron irradiation on the fracture toughness of austenitic SSs was also evaluated at dose levels relevant to BWR internals.

  4. Fatigue Enhancement of Undersized, Drilled Crack-Stop Holes

    E-Print Network [OSTI]

    Crain, Joshua Sakumura

    2010-04-20

    A common technique used to prevent the propagation of cracks in bridge girders is drilling crack-stop holes at the crack tips. By doing so, stress concentrations at the tip of the cracks are reduced and fatigue life of the ...

  5. Effect of Desiccation Cracks on Earth Embankments 

    E-Print Network [OSTI]

    Khandelwal, Siddharth

    2012-07-11

    Levees are earth structures used for flood protection. Due to their easy availability and low permeability, clays are the most common material used for the construction of levees. Clays are susceptible to desiccation cracks ...

  6. Delayed neutron emission measurements for U-235 and Pu-239 

    E-Print Network [OSTI]

    Chen, Yong

    2009-05-15

    The delayed neutron emission rates of U-235 and Pu-239 samples were measured accurately from a thermal fission reaction. A Monte Carlo calculation using the Geant4 code was used to demonstrate the neutron energy independence of the detector used...

  7. Fundamentals of Delayed Coking Joint Industry Project

    SciTech Connect (OSTI)

    Michael Volk Jr; Keith Wisecarver

    2005-10-01

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking. The following deliverables are scheduled from the two projects of the three-year JIP: (1) A novel method for enhancing liquid yields from delayed cokers and data that provide insight as to the optimum temperature to remove hydrogen sulfide from furnace gases. (2) An understanding of what causes foaming in c

  8. An investigation of penetrant techniques for detection of machining-induced surface-breaking cracks on monolithic ceramics

    SciTech Connect (OSTI)

    Forster, G.A.; Ellingson, W.A.

    1996-02-01

    The purpose of this effort was to evaluate penetrant methods for their ability to detect surface-breaking cracks in monolithic ceramic materials with an emphasis on detection of cracks generated by machining. There are two basic penetrant types, visible and fluorescent. The visible penetrant method is usually augmented by powder developers and cracks detected can be seen in visible light. Cracks detected by fluorescent penetrant are visible only under ultraviolet light used with or without a developer. The developer is basically a powder that wicks up penetrant from a crack to make it more observable. Although fluorescent penetrants were recommended in the literature survey conducted early in this effort, visible penetrants and two non-standard techniques, a capillary gaseous diffusion method under development at the institute of Chemical Physics in Moscow, and the {open_quotes}statiflux{close_quotes} method which involves use of electrically charged particles, were also investigated. SiAlON ring specimens (1 in. diameter, 3/4 in. wide) which had been subjected to different thermal-shock cycles were used for these tests. The capillary gaseous diffusion method is based on ammonia; the detector is a specially impregnated paper much like litmus paper. As expected, visible dye penetrants offered no detection sensitivity for tight, surface-breaking cracks in ceramics. Although the non-standard statiflux method showed promise on high-crack-density specimens, it was ineffective on limited-crack-density specimens. The fluorescent penetrant method was superior for surface-breaking crack detection, but successful application of this procedure depends greatly on the skill of the user. Two presently available high-sensitivity fluorescent penetrants were then evaluated for detection of microcracks on Si{sub 3}N{sub 4} and SiC from different suppliers. Although 50X optical magnification may be sufficient for many applications, 200X magnification provides excellent delectability.

  9. Contstraint effects of shallow cracks in structures containing fillet weld toe cracks 

    E-Print Network [OSTI]

    Neligon, Melinda T

    1995-01-01

    for structures containing a/W--O.l and a/W--O.5 fillet weld toe cracks. The Anderson-Dodds scaling model is applied to quantify the effects of finite size on J contour integral values for structures containing a/W=O.l and a/W=0.5 fillet weld toe cracks loaded...

  10. Characterization of cracking restraint at sawcut joints using the German Cracking Frame 

    E-Print Network [OSTI]

    Vepakomma, Shilpa

    2002-01-01

    shrinkage and creep. Early age creep and shrinkage also appear to be key factors of stress and cracking. Experiments were run to provide insight on the effect of shrinkage and creep on crack developments. The results were useful in evaluating the behavior...

  11. Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal

    E-Print Network [OSTI]

    Volinsky, Alex A.

    becomes equal to the fracture toughness, KIC, the crack will open and prop- agate. Stroh showed a crack [18]. Therefore, the fracture of most FCC metals is ductile. The chemical environment changes KIC and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology

  12. MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK

    E-Print Network [OSTI]

    Nairn, John A.

    MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK PROPAGATION." This new method has several advantages for numerical work on fracture. Compared to finite element analysis works well for calculating key fracture parameters such as J integral, stress intensity factors

  13. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    SciTech Connect (OSTI)

    Langton, C.

    2012-05-11

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  14. Soviet delays raise prices

    SciTech Connect (OSTI)

    Young, I.

    1992-01-15

    The breakup of the Soviet Union is causing massive disruptions to methanol exports. The changeover to a Commonwealth of independent States has created logistical problems which have led some shipments of Russian methanol to be cancelled and delayed other deliveries by up to two weeks. In recent years the Soviet Union has exported 700,000 m.t./year-900,000 m.t./year of methanol, mainly to Western Europe. The product is made at 750,000-m.t./year plants at Tomsk and Gubakha in Russia and transported by rail for shipment from the ports of Ventspils, Latvia, on the Baltic Sea and Yuzhnyy in Ukraine, on the Black Sea. The exports were handled by state export agency Soyuzagrochim, mainly under contract to West European traders and consumers in areas like Scandinavia and France.

  15. Biomaterials 28 (2007) 49014911 Stresscorrosion crack growth of SiNaKMgCaPO bioactive

    E-Print Network [OSTI]

    Ritchie, Robert

    2007-01-01

    Biomaterials 28 (2007) 4901­4911 Stress­corrosion crack growth of Si­Na­K­Mg­Ca­P­O bioactive the thermal expansion (in the range of 8.8­15.1 Â 10À6 1CÀ1 ) [19] ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials

  16. STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS

    SciTech Connect (OSTI)

    Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

    2009-05-01

    Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

  17. Crack-arrest behavior in SEN wide plates of low-upper-shelf base metal tested under nonisothermal conditions: WP-2 series

    SciTech Connect (OSTI)

    Naus, D.J.; Keeney-Walker, J.; Bass, B.R.; Robinson, G.C. Jr.; Iskander, S.K.; Alexander, D.J. [Oak Ridge National Lab., TN (United States); Fields, R.J.; deWit, R.; Low, S.R. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Schwartz, C.W. [Maryland Univ., College Park, MD (United States). Dept. of Mechanical Engineering; Johansson, I.B. [Royal Inst. of Tech., Stockholm (Sweden)

    1990-08-01

    The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory under the sponsorship of the Nuclear Regulatory Commission is conducting analytical and experimental studies aimed at understanding the circumstances that would initiate the growth of an existing crack in a reactor pressure vessel (RPV) and the conditions leading to arrest of a propagating crack. Objectives of these studies are to determine (1) if the material will exhibit crack-arrest behavior when the driving force on a crack exceeds the ASME limit, (2) the relationship between K{sub Ia} and temperature, and (3) the interaction of fracture modes (arrest, stable crack growth, unstable crack growth, and tensile instability) when arrest occurs at high temperatures. In meeting these objectives, crack-arrest data are being developed over an expanded temperature range through tests involving large thermally shocked cylinders, pressurized thermally shocked vessels, and wide-plate specimens. The wide-plate specimens provide the opportunity for a significant number of data points to be obtained at relatively affordable costs. These tests are designed to provide fracture-toughness measurements approaching or above the onset of the Charpy upper-shelf regime in a rising toughness region and with an increasing driving force. This document discusses test methodology and results. 23 refs., 92 figs., 25 tabs.

  18. High resolution digital delay timer

    DOE Patents [OSTI]

    Martin, Albert D. (Los Alamos, NM)

    1988-01-01

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

  19. Recommendations for the shallow-crack fracture toughness testing task within the HSST (Heavy-Section Steel Technology) Program

    SciTech Connect (OSTI)

    Theiss, T.J. (Oak Ridge National Lab., TN (USA))

    1990-09-01

    Recommendations for Heavy-Section Steel Technology Program's investigation into the influence of crack depth on the fracture toughness of a steel prototypic of those in a reactor pressure vessel are included in this report. The motivation for this investigation lies in the fact that probabilistic fracture mechanics evaluations show that shallow flaws play a dominant role in the likelihood of vessel failure, and shallow-flaw specimens have exhibited an elevated toughness compared with conventional deep-notch fracture toughness specimens. Accordingly, the actual margin of safety of vessels may be greater than that predicted using existing deep-notch fracture-toughness results. The primary goal of the shallow-crack project is to investigate the influence of crack depth on fracture toughness under conditions prototypic of a reactor vessel. A limited data base of fracture toughness values will be assembled using a beam specimen of prototypic reactor vessel material and with a depth of 100 mm (4 in.). This will permit comparison of fracture-toughness data from deep-cracked and shallow-crack specimens, and this will be done for several test temperatures. Fracture-toughness data will be expressed in terms of the stress-intensity factor and crack-tip-opening displacement. Results of this investigation are expected to improve the understanding of shallow-flaw behavior in pressure vessels, thereby providing more realistic information for application to the pressurized-thermal shock issues. 33 refs., 17 figs.

  20. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, Albert (Santa Fe, NM); Bell, Thomas M. (Santa Fe, NM); Rhodes, George W. (Albuquerque, NM)

    1994-01-01

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component.

  1. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, A.; Bell, T.M.; Rhodes, G.W.

    1994-10-04

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component. 5 figs.

  2. Fracture of surface cracks loaded in bending

    SciTech Connect (OSTI)

    Chao, Y.J.; Reuter, W.G.

    1997-12-31

    Theoretical background of the constraint effect in brittle fracture of solids is reviewed. Fracture test data from D6-aC, a high strength steel, using three-point-bend (SE(B)) specimens and surface cracked plate (SC(B)) specimens under bending are presented. It is shown that the SE(B) data has an elevated fracture toughness for increasing a/W, i.e., a crack geometry with a larger T/K corresponds to a higher K{sub c} which is consistent with the theoretical prediction. The fundamental fracture properties, i.e., the critical strain and the critical distance, determined from the SE(B) test data are then applied to the interpretation and prediction of the SC(B) test data. Reasonable agreement is achieved for the crack growth initiation site and the load.

  3. Environmentally assisted cracking of LWR materials.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Kassner, T. F.; Park, J. H.; Shack, W. J.; Zhang, J.; Brust, F. W.; Dong, P.

    1997-12-05

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2-0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  4. Reflective cracking of shear keys in multi-beam bridges 

    E-Print Network [OSTI]

    Sharpe, Graeme Peter

    2009-06-02

    strength to resist cracking from vehicular loads, but uneven temperature changes and shrinkage strains cause high tensile stresses in the shear key regions and lead to reflective cracking. The analyses showed the highest stresses were often times near...

  5. Pseudofunctional Delay Tests For High Quality Small Delay Defect Testing 

    E-Print Network [OSTI]

    Lahiri, Shayak

    2012-02-14

    Testing integrated circuits to verify their operating frequency, known as delay testing, is essential to achieve acceptable product quality. The high cost of functional testing has driven the industry to automatically-generated ...

  6. Environmentally assisted cracking in light water reactors

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Gruber, E.E. [and others

    1996-07-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from April 1995 to December 1995. Topics that have been investigated include fatigue of carbon and low-alloy steel used in reactor piping and pressure vessels, EAC of Alloy 600 and 690, and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests were conducted on ferritic steels in water that contained various concentrations of dissolved oxygen (DO) to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack-growth-rate tests were conducted on compact-tension specimens from several heats of Alloys 600 and 690 in simulated LWR environments. Effects of fluoride-ion contamination on susceptibility to intergranular cracking of high- and commercial- purity Type 304 SS specimens from control-tensile tests at 288 degrees Centigrade. Microchemical changes in the specimens were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials.

  7. Strip edge cracking simulation in cold rolling

    SciTech Connect (OSTI)

    Hubert, C.; Dubar, L.; Dubar, M.; Dubois, A.

    2011-01-17

    This research work focuses on a specific defect which occurs during cold rolling of steel strips: edge-serration. Investigations on the industrial processes have led to the conclusion that this defect is the result of the edge-trimming and cold rolling sequences. The aim of this research work is to analyze the effect of the cutting process and the cold rolling on cracks occurrence, especially on strip edges.This study is performed using an experimental testing stand called Upsetting Rolling Test (URT). It allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near trimmed industrial strip edges are deformed using the URT stand. Two sets of specimens with different stress states, obtained by annealing, are submitted to two reduction passes with extreme forward slips.Scanning electron microscopy observations added to 3D optical surface profiler topographies show that on one hand, forward slip has a major effect on cracks opening. On the other hand, cracks opening decreases according to high roll strip speed gradient. Concerning the heat-treated specimens, no crack appeared after all reduction passes, showing a large influence of the cutting process and consequently of the local stress state in the vicinity of the burnish and fracture regions.

  8. SCATTERING BY CRACKS BENEATH FLUIDSOLID INTERFACES

    E-Print Network [OSTI]

    Craster, Richard

    , and accurately determine the position of, cracks. The non­destructive testing of a solid to detect such flaws as the fluid coupling tends to zero is non­uniform, that is, the Rayleigh wave is not related to the Sch

  9. Digital radiographic systems detect boiler tube cracks

    SciTech Connect (OSTI)

    Walker, S. [EPRI, Charlotte, NC (United States)

    2008-06-15

    Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

  10. Stress corrosion cracking and crack tip characterization of Alloy X-750 in light water reactor environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    2011-01-01

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  11. Stress Corrosion Cracking and Crack Tip Characterization of Alloy X-750 in Light Water Reactor Environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  12. Soil cracking modelling using the mesh-free SPH method

    E-Print Network [OSTI]

    Bui, H H; Kodikara, J; Sanchez, M

    2015-01-01

    The presence of desiccation cracks in soils can significantly alter their mechanical and hydrological properties. In many circumstances, desiccation cracking in soils can cause significant damage to earthen or soil supported structures. For example, desiccation cracks can act as the preference path way for water flow, which can facilitate seepage flow causing internal erosion inside earth structures. Desiccation cracks can also trigger slope failures and landslides. Therefore, developing a computational procedure to predict desiccation cracking behaviour in soils is vital for dealing with key issues relevant to a range of applications in geotechnical and geo-environment engineering. In this paper, the smoothed particle hydrodynamics (SPH) method will be extended for the first time to simulate shrinkage-induced soil cracking. The main objective of this work is to examine the performance of the proposed numerical approach in simulating the strong discontinuity in material behaviour and to learn about the crack ...

  13. High resolution 20 GHz wideband delay generator

    E-Print Network [OSTI]

    Rodwell, Mark J. W.

    High resolution 20 GHz wideband delay generator S.L. Morton, K. Elliott and M. Rodwell A digitally resolution beamsteering applications, a delay generator is required to have a resolution better than 0.25 ps for a signal of 1.8 GHz. In 1989, Otsuji and Narumi [3] fabricated delay lines for delay generation, using

  14. Linear rotary optical delay lines Maksim Skorobogatiy*

    E-Print Network [OSTI]

    Skorobogatiy, Maksim

    Linear rotary optical delay lines Maksim Skorobogatiy* Department of Engineering Physics, École of analytical and semi-analytical solutions for the design of high-speed rotary optical delay lines that use of optical delay. Finally, two prototypes of rotary delay lines were fabricated using CNC machining

  15. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, R.D.

    1993-10-05

    A process is described for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded. 1 figures.

  16. Circumferential cracking of steam generator tubes

    SciTech Connect (OSTI)

    Karwoski, K.J.

    1997-04-01

    On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, {open_quote}Circumferential Cracking of Steam Generator Tubes.{close_quote} GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff`s assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness.

  17. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, Richard D. (Lisle, IL)

    1993-01-01

    A process for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded.

  18. Dynamical Event during Slow Crack Propagation

    SciTech Connect (OSTI)

    Ma {sup o}loy, Knut Jorgen; Schmittbuhl, Jean

    2001-09-03

    We address the role of material heterogeneities on the propagation of a slow rupture at laboratory scale. With a high speed camera, we follow an in-plane crack front during its propagation through a transparent heterogeneous Plexiglas block. We obtain two major results. First, the slip along the interface is strongly correlated over scales much larger than the asperity sizes. Second, the dynamics is scale dependent. Locally, mechanical instabilities are triggered during asperity depinning and propagate along the front. The intermittent behavior at the asperity scale is in contrast with the large scale smooth creeping evolution of the average crack position. The dynamics is described on the basis of a Family-Vicsek scaling.

  19. Structures for dense, crack free thin films

    DOE Patents [OSTI]

    Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

    2011-03-08

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  20. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    SciTech Connect (OSTI)

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection methods often need to be addressed as plants age. Shutdown inspection intervals can only be designed using creep and creep-fatigue crack growth techniques. (5) The use of crack growth procedures can aid in examining the seriousness of creep damage in structural components. How cracks grow can be used to assess margins on components and lead to further safe operation. After examining the pros and cons of all these methods, the R5 code was chosen as the most up-to-date and validated high temperature creep and creep fatigue code currently used in the world at present. R5 is considered the leader because the code: (1) has well established and validated rules, (2) has a team of experts continually improving and updating it, (3) has software that can be used by designers, (4) extensive validation in many parts with available data from BE resources as well as input from Imperial college's database, and (5) was specifically developed for use in nuclear plants. R5 was specifically developed for use in gas cooled nuclear reactors which operate in the UK and much of the experience is based on materials and temperatures which are experienced in these reactors. If the next generation advanced reactors to be built in the US used these same materials within the same temperature ranges as these reactors, then R5 may be appropriate for consideration of direct implementation within ASME code NH or Section XI. However, until more verification and validation of these creep/fatigue crack growth rules for the specific materials and temperatures to be used in the GEN IV reactors is complete, ASME should consider delaying this implementation. With this in mind, it is this authors opinion that R5 methods are the best available for code use today. The focus of this work was to examine the literature for creep and creep-fatigue crack growth procedures that are well established in codes in other countries and choose a procedure to consider implementation into ASME NH. It is very important to recognize that all creep and creep fatigue crack growth procedures that are part of high temperature

  1. Hierarchical Petascale Simulation Framework for Stress Corrosion Cracking

    SciTech Connect (OSTI)

    Vashishta, Priya

    2014-12-01

    Reaction Dynamics in Energetic Materials: Detonation is a prototype of mechanochemistry, in which mechanically and thermally induced chemical reactions far from equilibrium exhibit vastly different behaviors. It is also one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. The CACS group has performed multimillion-atom reactive MD simulations to reveal a novel two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine (RDX) crystal. Rapid production of N2 and H2O within ~10 ps is followed by delayed production of CO molecules within ~ 1 ns. They found that further decomposition towards the final products is inhibited by the formation of large metastable C- and O-rich clusters with fractal geometry. The CACS group has also simulated the oxidation dynamics of close-packed aggregates of aluminum nanoparticles passivated by oxide shells. Their simulation results suggest an unexpectedly active role of the oxide shell as a nanoreactor.

  2. An investigation of crack-tip stress field criteria of predicting cleavage-crack initiation

    SciTech Connect (OSTI)

    Keeney-Walker, J.; Bass, B.R.; Landes, J.D. (Oak Ridge National Lab., TN (United States))

    1991-09-01

    Cleavage-crack initiation in large-scale wide-plate (WP) specimens could not be accurately predicted from small, compact (CT) specimens by using a linear-elastic fracture-mechanics, K{sub Ic}, methodology. In the wide-plate tests conducted by the Heavy-Section Steel Technology Program at Oak Ridge National Laboratory, crack initiation has consistently occurred at stress-intensity (K{sub I}) values ranging from two to four times those predicted by the CT specimens. Studies were initiated to develop crack-tip stress field criteria incorporating effects of geometry, size, and constraint that will lead to improved predictions of cleavage initiation in WP specimens from CT specimens. The work centers around nonlinear two-and three-dimensional finite-element analyses of the crack-tip stress fields in these geometries. Analyses were conducted on CT and WP specimens for which cleavage initiation fracture had been measured in laboratory tests. The local crack-tip field generated for these specimens were then used in the evaluation of fracture correlation parameters to augment the K{sub I} parameter for predicting cleavage initiation. Parameters of hydrostatic constraint and of maximum principal stress, measured volumetrically, are included in these evaluations. The results suggest that the cleavage initiation process can be correlated with the local crack-tip fields via a maximum principal stress criterion based on achieving a critical area within a critical stress contour. This criterion has been successfully applied to correlate cleavage initiation in 2T-CT and WP specimen geometries. 23 refs., 16 figs., 5 tabs.

  3. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking

    SciTech Connect (OSTI)

    Das, S.K.; Ningileri, S.; Long, Z.; Saito, K.; Khraisheh, M.; Hassan, M.H.; Kuwana, K.; Han, Q.; Viswanathan, S.; Sabau, A.S.; Clark, J.; Hyrn, J. (ANL)

    2006-08-15

    Approximately 68% of the aluminum produced in the United States is first cast into ingots prior to further processing into sheet, plate, extrusions, or foil. The direct chill (DC) semi-continuous casting process has been the mainstay of the aluminum industry for the production of ingots due largely to its robust nature and relative simplicity. Though the basic process of DC casting is in principle straightforward, the interaction of process parameters with heat extraction, microstructural evolution, and development of solidification stresses is too complex to analyze by intuition or practical experience. One issue in DC casting is the formation of stress cracks [1-15]. In particular, the move toward larger ingot cross-sections, the use of higher casting speeds, and an ever-increasing array of mold technologies have increased industry efficiencies but have made it more difficult to predict the occurrence of stress crack defects. The Aluminum Industry Technology Roadmap [16] has recognized the challenges inherent in the DC casting process and the control of stress cracks and selected the development of 'fundamental information on solidification of alloys to predict microstructure, surface properties, and stresses and strains' as a high-priority research need, and the 'lack of understanding of mechanisms of cracking as a function of alloy' and 'insufficient understanding of the aluminum solidification process', which is 'difficult to model', as technology barriers in aluminum casting processes. The goal of this Aluminum Industry of the Future (IOF) project was to assist the aluminum industry in reducing the incidence of stress cracks from the current level of 5% to 2%. Decreasing stress crack incidence is important for improving product quality and consistency as well as for saving resources and energy, since considerable amounts of cast metal could be saved by eliminating ingot cracking, by reducing the scalping thickness of the ingot before rolling, and by eliminating butt sawing. Full-scale industrial implementation of the results of the proposed research would lead to energy savings in excess of 6 trillion Btu by the year 2020. The research undertaken in this project aimed to achieve this objective by a collaboration of industry, university, and national laboratory personnel through Secat, Inc., a consortium of aluminum companies. During the four-year project, the industrial partners and the research team met in 16 quarterly meetings to discuss research results and research direction. The industrial partners provided guidance, facilities, and experience to the research team. The research team went to two industrial plants to measure temperature distributions in commercial 60,000-lb DC casting ingot production. The project focused on the development of a fundamental understanding of ingot cracking and detailed models of thermal conditions, solidification, microstructural evolution, and stress development during the initial transient in DC castings of the aluminum alloys 3004 and 5182. The microstructure of the DC casting ingots was systematically characterized. Carefully designed experiments were carried out at the national laboratory and university facilities as well as at the industrial locations using the industrial production facilities. The advanced computational capabilities of the national laboratories were used for thermodynamic and kinetic simulations of phase transformation, heat transfer and fluid flow, solidification, and stress-strain evolution during DC casting. The achievements of the project are the following: (1) Identified the nature of crack formation during DC casting; (2) Developed a novel method for determining the mechanical properties of an alloy at the nonequilibrium mushy zone of the alloy; (3) Measured heat transfer coefficients (HTCs) between the solidifying ingot and the cooling water jet; (4) Determined the material constitutive model at high temperatures; and (5) Developed computational capabilities for the simulation of cracking formation in DC casting ingot. The models and the database de

  4. Technical Letter Report on the Cracking of Irradiated Cast Stainless Steels with Low Ferrite Content

    SciTech Connect (OSTI)

    Chen, Y.; Alexandreanu, B.; Natesan, K.

    2014-11-01

    Crack growth rate and fracture toughness J-R curve tests were performed on CF-3 and CF-8 cast austenite stainless steels (CASS) with 13-14% of ferrite. The tests were conducted at ~320°C in either high-purity water with low dissolved oxygen or in simulated PWR water. The cyclic crack growth rates of CF-8 were higher than that of CF-3, and the differences between the aged and unaged specimens were small. No elevated SCC susceptibility was observed among these samples, and the SCC CGRs of these materials were comparable to those of CASS alloys with >23% ferrite. The fracture toughness values of unirradiated CF-3 were similar between unaged and aged specimens, and neutron irradiation decreased the fracture toughness significantly. The fracture toughness of CF-8 was reduced after thermal aging, and declined further after irradiation. It appears that while lowering ferrite content may help reduce the tendency of thermal aging embrittlement, it is not very effective to mitigate irradiation-induced embrittlement. Under a combined condition of thermal aging and irradiation, neutron irradiation plays a dominant role in causing embrittlement in CASS alloys.

  5. Hot Rolling Scrap Reduction through Edge Cracking and Surface...

    Broader source: Energy.gov (indexed) [DOE]

    Our Approach use a precompetitive material to develop new modeling technology (AA-7050) account for the anisotropic behavior during crack growth. validate model to...

  6. Shrinkage - cracking characteristics of structural lightweight concrete 

    E-Print Network [OSTI]

    McKeen, Robert Gordon

    1969-01-01

    restraint of the material, such as reinforcement and external fri. ction 28 (h) chemical admixtures employed (i) unit water content 2. 4 ~fk' f. C 2. 4. 1 General The cracking of concrete has been a subject of interest to desi. gners for many years... were made on two six by t. )elve in. c; linders from each batch of concrete for purposes of control. . The pecimens were moist cured 14 days prior to testing. Testing was performed in accordance with ASTM C39-64. The data were taken to provid...

  7. 3:2:1 Crack Spread

    Gasoline and Diesel Fuel Update (EIA)

    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 Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustments (Billion Cubic Feet) Wyoming Dry NaturalPrices1 Table 1.10 CoolingNotes &* j o n5 1:2:1 Crack

  8. Design, operation factors can up coker liquid yields. [Delayed liquid cooling

    SciTech Connect (OSTI)

    Elliott, J.D. (Foster Wheeler Corp., Clinton, NJ (US))

    1991-02-04

    Among refineries with delayed cokers, there is now major incentive to maximize coker fresh feed throughput while producing maximum possible liquid yields. There are design features and operating considerations that can increase liquid yields. Maximizing coke throughput is typically a necessity in overall refinery operations because coker capacity to process the bottom of the barrel can be a bottleneck to the entire refinery crude throughput. The incentive for achieving the maximum liquid yield from a coker is: clean distillates, even cracked distillates, are valuable while fuel grade coke is not. Another way to look at a maximum liquid yield coker operation is as a minimum coke yield operation.

  9. High Quality Compact Delay Test Generation 

    E-Print Network [OSTI]

    Wang, Zheng

    2011-08-08

    Delay testing is used to detect timing defects and ensure that a circuit meets its timing specifications. The growing need for delay testing is a result of the advances in deep submicron (DSM) semiconductor technology and the increase in clock...

  10. Uncertainty evaluation of delayed neutron decay parameters 

    E-Print Network [OSTI]

    Wang, Jinkai

    2009-05-15

    In a nuclear reactor, delayed neutrons play a critical role in sustaining a controllable chain reaction. Delayed neutron’s relative yields and decay constants are very important for modeling reactivity control and have been studied for decades...

  11. A Fast Algorithm for Nonstationary Delay Estimation

    E-Print Network [OSTI]

    So, Hing-Cheung

    to the explicit time delay estimator (ETDE) algorithm 4] but it is more computationally e cient and provides more

  12. Composite tube cracking in kraft recovery boilers: A state-of-the-art review

    SciTech Connect (OSTI)

    Singbeil, D.L.; Prescott, R.; Keiser, J.R.; Swindeman, R.W.

    1997-07-01

    Beginning in the mid-1960s, increasing energy costs in Finland and Sweden made energy recovery more critical to the cost-effective operation of a kraft pulp mill. Boiler designers responded to this need by raising the steam operating pressure, but almost immediately the wall tubes in these new boilers began to corrode rapidly. Test panels installed in the walls of the most severely corroding boiler identified austenitic stainless steel as sufficiently resistant to the new corrosive conditions, and discussions with Sandvik AB, a Swedish tube manufacturer, led to the suggestion that coextruded tubes be used for water wall service in kraft recovery boilers. Replacement of carbon steel by coextruded tubes has solved most of the corrosion problems experienced by carbon steel wall tubes, however, these tubes have not been problem-free. Beginning in early 1995, a multidisciplinary research program funded by the US Department of Energy was established to investigate the cause of cracking in coextruded tubes and to develop improved materials for use in water walls and floors of kraft recovery boilers. One portion of that program, a state-of-the-art review of public- and private-domain documents related to coextruded tube cracking in kraft recovery boilers is reported here. Sources of information that were consulted for this review include the following: tube manufacturers, boiler manufacturers, public-domain literature, companies operating kraft recovery boilers, consultants and failure analysis laboratories, and failure analyses conducted specifically for this project. Much of the information contained in this report involves cracking problems experienced in recovery boiler floors and those aspects of spout and air-port-opening cracking not readily attributable to thermal fatigue. 61 refs.

  13. Dynamical Systems with Delays Benefits and Detriments

    E-Print Network [OSTI]

    to what the system has exhibited in the past, and current information signals actually are not available Geographical Location 1 Production DELAY Headquarters Ordering Information Exchanging Decision Making DELAY1 Dynamical Systems with Delays Benefits and Detriments I. INTRODUCTION A feedback control system

  14. Dynamical Systems with Delays Benefits and Detriments

    E-Print Network [OSTI]

    delays arise Manufacturer Geographical Location 1 Production DELAY Headquarters Ordering Information1 Dynamical Systems with Delays Benefits and Detriments I. INTRODUCTION A feedback control system is composed of a process to be controlled, a set of sensors with access to information signals from the plant

  15. SPONTANEOUS AND EXPLICIT ESTIMATION OF TIME DELAYS

    E-Print Network [OSTI]

    So, Hing-Cheung

    , called the explicit time delay estimator (ETDE), is rst developed to nd the di erential delay of a signal through only one propagation path. Basically, the ETDE is an adaptive FIR lter whose coe cients it can provide direct delay measurements on a sample-by-sample basis. The ETDE performance surface

  16. Experimental Determination of Crack Driving Forces in Integrated Structures

    E-Print Network [OSTI]

    Suo, Zhigang

    8/2/2004 1 Experimental Determination of Crack Driving Forces in Integrated Structures Jun He in a structure, the crack driving force G is the reduction of the elastic energy in the structure, associated. In practice, however, such a calculation is prohibitively difficult for integrated structures of complex

  17. Crack patterns in thin lms Z. Cedric Xiaa

    E-Print Network [OSTI]

    Hutchinson, John W.

    Crack patterns in thin ®lms Z. Cedric Xiaa , John W. Hutchinsonb, * a Ford Research Laboratory elastic ®lms. Speci®c examples are presented for ®lms subject to equi-biaxial residual tensile stress Elsevier Science Ltd. All rights reserved. Keywords: Crack propagation; Thin ®lms; Integral equations 1

  18. Fracture mechanics analysis of slow crack growth in polyethylene 

    E-Print Network [OSTI]

    Self, Robert Alan

    1997-01-01

    Slow crack growth in polyethylene is often the limiting factor in long-term service of plastic pipe or other structural applications. A new test method and analysis method was developed to study slow crack growth in polyethylene. Two high density...

  19. WATER PERMEABILITY OF CRACKED CEMENTITIOUS MICHAEL LEPECH & VICTOR C. LI

    E-Print Network [OSTI]

    Lepech, Michael D.

    of ECC material exhibits a water permeability close to that of uncracked concrete when strained up to 1 structures. With compressive strengths twice that of normal concrete and a low water permeability coefficient is the permeability of concrete structures in the cracked state. Regardless of the reason for cracking, whether

  20. CRACKING OF PRESTRESSED CONCRETE CONTAINMENTS DUE TO INTERNAL PRESSURE

    E-Print Network [OSTI]

    applied to a 1/14 scale test structure. Observed values agreed well with predicted values. #12;Mac of a containment vessel (wall segment tests) reported in this paper and Ref. 4 and 5, and a test of a 1/14 size reached, all cracks observed in the tests had formed. At greater strains certain existing cracks became

  1. The Simulation of Paint Cracking and Peeling Eric Paquette

    E-Print Network [OSTI]

    Montréal, Université de

    The Simulation of Paint Cracking and Peeling Eric Paquette D´ep. I.R.O., Universit´e de Montr of time results in cracking and peeling of layers such as paint. To include these ef- fects in computer of paint peeling. We present a new approach which computes such a simulation on surfaces. Our simulation

  2. Predicting crack growth in continuous-fiber composite materials

    SciTech Connect (OSTI)

    Cordes, J.A.; Yazici, R.

    1995-12-31

    Pre-notched composite lamina with unidirectional fibers were studied experimentally and using finite element analysis. Experiments were conducted on notched graphite/aluminum and glass/epoxy panels and the results were compared to a finite element method. Under remote tensile loading, cracks in the graphite/aluminum panels propagated perpendicular to the applied load without stable crack growth. In the glass/epoxy panels, crack propagation was initially stable and parallel to the fibers. A nonlinear damage zone method (DZM) was used to predict the crack growth directions, estimate damages, model stable and unstable crack growths, and predict the loads at failure. For both materials, the predicted loads at failure were within 20% of experimental loads.

  3. ffe1098 FFE March 7, 2007 21:55 Crack tip displacements of microstructurally small cracks in 316L steel

    E-Print Network [OSTI]

    Cizelj, Leon

    -strain finite element crystal plasticity model. The model consists of 212 randomly shaped, sized and oriented plane. Keywords crack tip displacements; crystal plasticity; polycrystals; small cracks. NOMENCLATURE a) and sliding displacements (CTSD) for single crystal and polycrystal models, considering also different

  4. The effect of crack surface interaction on the stress intensity factor in Mode III crack growth in round shafts

    E-Print Network [OSTI]

    Vaziri, Ashkan

    in round shafts A. Vaziri 1 , H. Nayeb-Hashemi * Department of Mechanical, Industrial and Manufacturing March 2004; accepted 31 March 2004 Available online 6 July 2004 Abstract Turbine-generator shafts and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often

  5. Mixed-mode, high-cycle fatigue-crack growth thresholds in II. Quantication of crack-tip shielding

    E-Print Network [OSTI]

    Ritchie, Robert

    -tip shielding J.P. Campbell, R.O. Ritchie * Department of Materials Science and Mineral Engineering, University 2000; accepted 11 May 2000 Abstract The role of crack-tip shielding in in¯uencing mixed-mode (mode I crack-tip shielding with respect to both the mode I and mode II applied loading, enabling an estimation

  6. Short and Large Crack, Mixed-Mode Fatigue-Crack Growth Thresholds in Ti-6Al-4V1

    E-Print Network [OSTI]

    Ritchie, Robert

    and control of failures due to high cycle fatigue (HCF) in turbine engine components is currently one, Dr. J. P. Campbell and Professor R. O. Ritchie2 Department of Materials Science and Engineering-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat

  7. Fault simulation and test generation for small delay faults 

    E-Print Network [OSTI]

    Qiu, Wangqi

    2007-04-25

    Delay faults are an increasingly important test challenge. Traditional delay fault models are incomplete in that they model only a subset of delay defect behaviors. To solve this problem, a more realistic delay fault model has been developed which...

  8. Cracking in liquid petroleum gas Horton spheres

    SciTech Connect (OSTI)

    Trivedi, D.K. Gupta, S.C.

    1997-07-01

    A gas processing plant on the western coast of India produces sweet gas after processing sour natural gas. Liquid petroleum gas (LPG) is recovered from the sweet gas. The LPG, containing a H{sub 2}S concentration of 10 ppm to 20 ppm, is stored in Horton spheres, each 17 m in diameter with a capacity of {minus}27 C to 55 C. Horton spheres for containing liquid petroleum gas (LPG) were fabricated on-site using prestressed plates of high-strength carbon steel (CS) SA 537 Class-1 with post-weld heat treatment. High-residual tensile stresses and hydrogen absorption from H{sub 2}S present in LPG could be the cause of cracking at weld and heat-affected zone interfaces at high hardness locations. Recommendations are given for inspection and use of lower-strength CS and improved welding procedures.

  9. Controlling the Delay of Small Flows in Datacenters

    E-Print Network [OSTI]

    Carra, Damiano

    and CAPEX and ignore designs which could help reduce delay of delay sensitive flows. The flow routing

  10. Delayed feedback control of unstable steady states with high-frequency modulation of the delay

    E-Print Network [OSTI]

    Aleksandar Gjurchinovski; Thomas Jüngling; Viktor Urumov; Eckehard Schöll

    2013-08-21

    We analyze the stabilization of unstable steady states by delayed feedback control with a periodic time-varying delay in the regime of a high-frequency modulation of the delay. The average effect of the delayed feedback term in the control force is equivalent to a distributed delay in the interval of the modulation, and the obtained distribution depends on the type of the modulation. In our analysis we use a simple generic normal form of an unstable focus, and investigate the effects of phase-dependent coupling and the influence of the control loop latency on the controllability. In addition, we have explored the influence of the modulation of the delays in multiple delay feedback schemes consisting of two independent delay lines of Pyragas type. A main advantage of the variable delay is the considerably larger domain of stabilization in parameter space.

  11. The cracking and spalling of multilayered chromium coatings

    SciTech Connect (OSTI)

    Joergensen, O.; Horsewell, A.; Soerensen, B.F. [Risoe National Lab., Roskilde (Denmark). Materials Dept.] [Risoe National Lab., Roskilde (Denmark). Materials Dept.; Leisner, P. [Technical Univ. of Denmark, Lyngby (Denmark). Centre of Advanced Electroplating] [Technical Univ. of Denmark, Lyngby (Denmark). Centre of Advanced Electroplating

    1995-11-01

    Cracks in a chromium coating on a steel substrate which are caused by residual stresses developed during an electroplating process are examined. The chromium coating, formed as a multilayer by alternating electroplating utilizing direct current (DC) and periodic current reversal (PR), is in a state of biaxial tensile stress due to a volume contraction in the successive DC layers which occurs during deposition. A uniform biaxial misfit strain idealizes this layerwise contraction. The state of stress in the multilayer is model during laminate theory. Special emphasis is given to the influence of the substrate flexibility on the stress build-up. It is shown that the flexibility of the substrate produces an equal biaxial bending moment in the coating. At a critical coating thickness, the chromium multilayer cracks and spalls off the substrate. The radius of curvature of detached coating fragments provides a measure of the size of the bending moment and, indirectly, of the misfit strain. The observed fracture mechanism is qualitatively divided into cracks channeling in the coating and debonding cracks running in the interface between the coating and the substrate. Long crack asymptotic solutions for the two distinct crack types are presented. The fracture analyses of the multilayered chromium coating show the functional dependence of relative layer and substrate thicknesses and flexibility on the energy release rate for crack propagation.

  12. Reliability of steam generator tubes with axial cracks

    SciTech Connect (OSTI)

    Cizelj, L.; Mavko, B. [Jozef Stefan Inst., Ljubljana (Slovenia). Reactor Engineering Div.; Vencelj, P. [Univ. of Ljubljana (Slovenia). Faculty of Mathematics and Physics

    1996-11-01

    An approach for estimating the failure probability of tubes containing through-wall axial cracks has already been proposed by the authors. It is based on probabilistic fracture mechanics and accounts for scatter in tube geometry and material properties, scatter in residual and operational stresses responsible for crack propagation, and characteristics of nondestructive examination and plugging procedures (e.g., detection probability, sizing accuracy, human errors). Results of preliminary tests demonstrated wide applicability of this approach and triggered some improvements. The additions to the model are extensively discussed in this paper. Capabilities are demonstrated by results of analysis of steam generator no. 1 in Slovenian nuclear power plant located in Krsko after the 1992 inspection and plugging campaign. First, the number of cracked tubes and the crack length distribution were estimated using data obtained by the 100% motorized pancake coil inspection. The inspection and plugging activities were simulated in the second step to estimate the efficiency of maintenance in terms of single and multiple-tube rupture probabilities. They were calculated as a function of maximum allowable crack length. The importance of human errors and some limitations of present nondestructive examination techniques were identified. The traditional wall thickness and crack-length-based plugging criteria are compared. The crack-length-based criterion is shown to be more efficient and more safe, especially because of strong suppression effect on probability of multiple-tube rupture. The results are considered to be important for safety and maintenance of existing plants and for further research.

  13. Three-dimensional crack growth assessment by microtopographic examination

    SciTech Connect (OSTI)

    Lloyd, W.R.; Piascik, R.S.

    1995-12-31

    The initial stage of the stable tearing process in two 2.3 mm sheet 2024-T3 aluminum alloy M(T) specimens are analyzed using fracture surface microtopography reconstruction techniques. The local crack tip opening angles (CTOA) in the interior of the specimens are determined relative to both crack extension and through-thickness position. The microtopographic analysis of cracks grown in the L-T and T-L orientations reveal that interior CTOA is comparable to those measured on the surface using standard optical analysis methods. Similar to surface CTOA results, interior (mid-thickness) CTOA exhibit a transient behavior; CTOA transitions from high angles, at near crack initiation, to a lower steady-state value of 5 deg. and 4.2 deg. for L-T and T-L, respectively, at crack lengths greater than 1.5mm. Fracture surface topographic projection maps are used to study the evolution of crack front tunneling during the initial stage of the fracture process. Stable tearing initiates at mid-thickness followed by a crack front tunneling process to a depth of approximately 2mm. A brief discussion of the basis of the fracture process reconstruction method is provided and comments on the general utility of microtopographic fracture surface examination for general assessment of elastic-plastic and fully-plastic fracture processes are made.

  14. Fatigue crack growth behavior of Ti-1100 at elevated temperature

    SciTech Connect (OSTI)

    Maxwell, D.C.; Nicholas, T.

    1995-12-31

    Effects of temperature, frequency, and cycles with superimposed hold times are evaluated in Ti-1100 in order to study the complex creep-fatigue-environment interactions in this material. Crack growth rate tests conducted at cyclic loading frequency of 1.0 Hz show that raising the temperature from 593 to 650 C has only a slightly detrimental effect on crack growth rate, although these temperatures produce growth rates significantly higher than at room temperature. From constant {Delta}K tests, the effects of temperature at constant frequency show a minimum crack growth rate at 250 C. From the minimum crack growth rate at 250 C, the crack growth rate increases linearly with temperature. Increases in frequency at constant temperatures of 593 and 650 C produce a continuous decrease in growth rate in going from 0.001 to 1.0 Hz, although the behavior is primarily cycle dependent in this region. Tests at 1.0 Hz with superimposed hold times from 1 to 1,000 s are used to evaluate creep-fatigue-environment interactions. Hold times at maximum load are found to initially decrease and then increase the cyclic crack growth rate with increasing duration. This is attributed to crack-tip blunting during short hold times and environmental degradation at long hold times. Hold times at minimum load show no change in growth rates, indicating that there is no net environmental degradation to the bulk material beyond that experienced during the baseline 1 Hz cycling.

  15. Standard test method for creep-fatigue crack growth testing

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the determination of creep-fatigue crack growth properties of nominally homogeneous materials by use of pre-cracked compact type, C(T), test specimens subjected to uniaxial cyclic forces. It concerns fatigue cycling with sufficiently long loading/unloading rates or hold-times, or both, to cause creep deformation at the crack tip and the creep deformation be responsible for enhanced crack growth per loading cycle. It is intended as a guide for creep-fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. Therefore, this method requires testing of at least two specimens that yield overlapping crack growth rate data. The cyclic conditions responsible for creep-fatigue deformation and enhanced crack growth vary with material and with temperature for a given material. The effects of environment such as time-dependent oxidation in enhancing the crack growth ra...

  16. Thermal engine

    SciTech Connect (OSTI)

    Karnes, T.E.; Trupin, R.J.

    1984-01-03

    A thermal engine utilizing a strip of nitinol material or other thermally responsive shape memory effect material to drive a reciprocating output shaft, said strip of material forming a common wall between two different alternating temperature sources which thermally cycle the material.

  17. Stress-corrosion cracking of copper single crystals

    SciTech Connect (OSTI)

    Sieradzki, K.; Newman, R.C.; Sabatini, R.L.

    1984-10-01

    Constant extension rate tests have been carried out in a sodium nitrite solution. Crack velocities up to 30 nm per second were obtained at 30/sup 0/C. If dynamic straining is stopped, the cracks apparently stop growing within about 20 ..mu..m. The steps between adjacent flat facets are more energy-absorbing than in ..cap alpha..-brass, providing a possible explanation for the importance of dynamic strain. Simultaneous acoustic emission and electrochemical current transients suggest that cracking proceeds by discontinuous cleavage.

  18. Tearing of thin sheets: Cracks interacting through an elastic ridge

    E-Print Network [OSTI]

    Fabian Brau

    2014-12-17

    We study the interaction between two cracks propagating quasistatically during the tearing of a thin brittle sheet. We show that the cracks attract each other following a path described by a power law resulting from the competition between elastic and fracture energies. The power law exponent (8/11) is in close agreement with experiments. We also show that a second (asymptotic) regime, with an exponent of 9/8, emerges for small distances between the two crack tips due to the finite transverse curvature of the elastic ridge joining them.

  19. White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel!

    E-Print Network [OSTI]

    Cambridge, University of

    ! quenched! and! untempered! steel! normally! used! in! the! manufacture! of! bearings.!The!varieties!of!cracks!studied!include!sparsely!distributed!martensite(lubricant!interactions,!or!hydrogen!trapping!can!be!studied!further.! ! Keywords:!bearing!steel,!indentation!cracks,!cracked!martensite,!grain(boundary!decohesion,! surface! 1! White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel! ! W

  20. Modeling of crack initiation, propagation and coalescence in rocks

    E-Print Network [OSTI]

    Gonçalves da Silva, Bruno Miguel

    2009-01-01

    Natural or artificial fracturing of rock plays a very important role in geologic processes and for engineered structures in and on rock. Fracturing is associated with crack initiation, propagation and coalescence, which ...

  1. Crack coalescence in rock-like material under cycling loading

    E-Print Network [OSTI]

    Ko, Tae Young, 1973-

    2005-01-01

    A total of 170 tests (68 tests for monotonic loading, 102 tests for cyclic loading) have been performed to investigate crack initiation, propagation and coalescence. The specimens have two pre-existing flaws which are ...

  2. From thermally activated to viscosity controlled fracture of biopolymer hydrogels

    E-Print Network [OSTI]

    T. Baumberger; O. Ronsin

    2008-10-22

    We report on rate-dependent fracture energy measurements over three decades of steady crack velocities in alginate and gelatin hydrogels. We evidence that, irrespective of gel thermo-reversibility, thermally activated "unzipping" of the non-covalent cross-link zones results in slow crack propagation, prevaling against the toughening effect of viscous solvent drag during chain pull-out, which becomes efficient above a few mm.s$^{-1}$. We extend a previous model [Baumberger {\\it et al.} Nature Materials, {\\bf 5}, 552 (2006)] to account for both mechanisms, and estimate the microscopic unzipping rates.

  3. Analytical determination of critical crack size in solar cells

    SciTech Connect (OSTI)

    Chen, C.P.

    1988-05-01

    Although solar cells usually have chips and cracks, no material specifications concerning the allowable crack size on solar cells are available for quality assurance and engineering design usage. Any material specifications that the cell manufacturers use were developed for cosmetic reasons that have no technical basis. Therefore, the Applied Solar Energy Corporation (ASEC) has sponsored a continuing program for the fracture mechanics evaluation of GaAs. Fracture mechanics concepts were utilized to develop an analytical model that can predict the critical crack size of solar cells. This model indicates that the edge cracks of a solar cell are more critical than its surface cracks. In addition, the model suggests that the material specifications on the allowable crack size used for Si solar cells should not be applied to GaAs solar cells. The analytical model was applied to Si and GaAs solar cells, but it would also be applicable to the semiconductor wafers of other materials, such as a GaAs thin film on a Ge substrate, using appropriate input data.

  4. OPTIMAL POWER/DELAY TRADE-OFFS IN WIRELESS COMMUNICATIONS SMALL DELAY ASYMPTOTICS

    E-Print Network [OSTI]

    Berry, Randall

    OPTIMAL POWER/DELAY TRADE-OFFS IN WIRELESS COMMUNICATIONS ­ SMALL DELAY ASYMPTOTICS Randall A@ece.northwestern.edu ABSTRACT In this paper we consider the optimal trade-off between av- erage transmission power and average the behavior of this trade-off in the regime of asymptotically large power and small delay. Our focus

  5. Optimal power-delay trade-offs in fading channels -small delay asymptotics

    E-Print Network [OSTI]

    Berry, Randall

    1 Optimal power-delay trade-offs in fading channels - small delay asymptotics Randall A. Berry Dept, we study the behavior of the optimal power-delay trade-off for a single user in the regime@ece.northwestern.edu Abstract When transmitting stochastically arriving data over fading channels there is an inherent trade

  6. Isochronal synchronization of delay-coupled systems

    E-Print Network [OSTI]

    Ira B. Schwartz; Leah B. Shaw

    2007-02-25

    We consider small network models for mutually delay-coupled systems which typically do not exhibit stable isochronally synchronized solutions. We show that for certain coupling architectures which involve delayed self feedback to the nodes, the oscillators become isochronally synchronized. Applications are shown for both incoherent pump coupled lasers and spatio-temporal coupled fiber ring lasers.

  7. MODEL DG535 Digital Delay / Pulse Generator

    E-Print Network [OSTI]

    Berns, Hans-Gerd

    MODEL DG535 Digital Delay / Pulse Generator 1290-D Reamwood Avenue Sunnyvale, CA 94089 U.S.A. Phone/2000 #12;i DG535 DIGITAL DELAY / PULSE GENERATOR OPERATION AND SERVICE MANUAL Table of Contents CONDENSED Sequence Sheet #4 Rate Generators Sheet #5 Power Supply and Dropout Detection Sheet #6 System Connectors

  8. DELAY DIFFERENTIAL EQUATIONS IN SINGLE SPECIES DYNAMICS

    E-Print Network [OSTI]

    Ruan, Shigui

    dynamics. Let x(t) denote the population size at time t; let b and d denote the birth rate and death rate Equations 10. Periodicity 11. State Dependent Delays 12. Diffusive Models with Delay References O. Arino et rate of the population. The solution of equation (1.1) with an initial population x(0) = x0 is given

  9. Mining Train Delays Boris Cule1

    E-Print Network [OSTI]

    Antwerpen, Universiteit

    Mining Train Delays Boris Cule1 , Bart Goethals1 , Sven Tassenoy2 , and Sabine Verboven2,1 1, Belgium 2 INFRABEL - Network, Department of Innovation, Barastraat 110, 1070 Brussels, Belgium Keywords Pattern Mining, Data Analysis, Train Delays Abstract The Belgian railway network has a high traffic

  10. Strengthening, Crack Arrest And Multiple Cracking In Brittle Materials Using Residual Stresses.

    DOE Patents [OSTI]

    Green, David J. (State College, PA); Sglavo, Vincenzo M. (Roncegno, IT); Tandon, Rajan (Fremont, CA)

    2003-02-11

    Embodiments include a method for forming a glass which displays visible cracking prior to failure when subjected to predetermined stress level that is greater than a predetermined minimum stress level and less than a failure stress level. The method includes determining a critical flaw size in the glass and introducing a residual stress profile to the glass so that a plurality of visible cracks are formed prior to failure when the glass is subjected to a stress that is greater than the minimum stress level and lower than the critical stress. One method for forming the residual stress profile includes performing a first ion exchange so that a first plurality of ions of a first element in the glass are exchanged with a second plurality of ions of a second element that have a larger volume than the first ions. A second ion exchange is also performed so that a plurality of the second ions in the glass are exchanged back to ions of the first element.

  11. Multiple use of waste catalysts with and without regeneration for waste polymer cracking

    SciTech Connect (OSTI)

    Salmiaton, A.; Garforth, A.A.

    2011-06-15

    Waste plastics contain a substantial number of valuable chemicals. The wastes from post-consumer as well as from industrial production can be recycled to valuable chemical feedstock, which can be used in refineries and/or petrochemical industries. This chemical recycling process is an ideal approach in recycling the waste for a better environment. Polymer cracking using a laboratory fluidised bed reactor concentrated on the used highly contaminated catalyst, E-Cat 2. Even though E-Cat 2 had low activity due to fewer acid sites, the products yielded were similar with amorphous ASA and were far better than thermal cracking. The high levels of heavy metals, namely nickel and vanadium, deposited during their lifetime as an FCC catalyst, did not greatly affect on the catalyst activity. It was also shown that E-Cat 2 could be used with and without regeneration. Although there was more deactivation when there was no regeneration step, the yield of gases (C{sub 2}-C{sub 7}) remained fairly constant. For the first time, these results indicate that 'waste' FCC catalyst (E-Cat) is a good candidate for future feedstock recycling of polymer waste. The major benefits of using E-Cat are a low market price, the ability to tolerate reuse and regeneration capacity.

  12. Fatigue crack growth behavior of Al-Li alloy 1441

    SciTech Connect (OSTI)

    Prakash, R.V.; Parida, B.K.

    1995-12-31

    Fatigue crack growth behavior of Al-Li alloy 1441 having a marginally lower lithium content, compared to 80xx and 20xx series Al-Li alloys is presented in this paper. This investigation was conducted on single edge tension--SE(T)--specimens, under constant amplitude as well as under MiniLCA flight spectrum loading with the specific objective of determining the effects of stress ratio, orientation, thickness and cladding. Three thicknesses were considered: 1.2 mm(clad and unclad), 2.0 mm(clad and unclad) and 8.0 mm unclad. Constant amplitude fatigue tests were conducted at stress ratios of {minus}0.3, 0.1 and 0.7. Testing was performed under ambient conditions and along three orientations, namely L-T, T-L and L+45 degrees. Crack growth characteristics of this alloy are compared with that of BS:L73 (2014-T4 equivalent) for assessing the possibility of replacing BS:L73. Significant effect of stress ratio on crack growth rate was observed in all thicknesses. However, in case of 1.2 and 2.0 mm thick sheets, the effect was minimal at intermediate-crack growth regime. The orientation of the specimen does not adversely affect the fatigue crack growth behavior of 8.0 mm and 2.0 mm thick specimens. However, for 1.2 mm unclad sheet crack growth resistance in L-T direction was found to be superior to that along T-L direction. In majority of test cases considered, no significant effect was observed on crack growth rate due to thickness or cladding. Crack growth characteristics of Al-Li alloy 1441 and Al-Cu alloy BS:L73 under constant amplitude as well as MiniLCA spectrum loading are similar in the low and intermediate-crack growth rate regime. Based on these observations, it is felt that this Al-Li alloy has the potential for future aerospace applications.

  13. Tarmac delay policies : a passenger-centric analysis

    E-Print Network [OSTI]

    Vanderboll, Allison Elizabeth (Allison Sunny Elizabeth)

    2013-01-01

    In this work, we analyze the effectiveness of the 2010 Tarmac Delay Rule from a passenger-centric point of view. The Tarmac Delay Rule aims to protect enplaned passengers on commercial aircraft from excessively long delays ...

  14. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    Solar Thermal Collectors .is solar energy. Solar thermal collector arrays can be usedon integrating solar thermal collectors with desalination

  15. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    and thermal energy storage in solar thermal applications,"aided or powered by solar thermal energy. A section is alsoexhaustive review of solar thermal energy systems has been

  16. Advanced Thermal Control

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

    thermal models power density cost lifetime Advanced Thermal Interface Materials Advanced Heat Transfer Technologies Air Cooling Thermal System Performance and Integration Thermal...

  17. Boundary integral formulation for interfacial cracks in thermodiffusive bimaterials

    E-Print Network [OSTI]

    L. Morini; A. Piccolroaz

    2015-04-29

    An original boundary integral formulation is proposed for the problem of a semi-infinite crack at the interface between two dissimilar elastic materials in the presence of heat flows and mass diffusion. Symmetric and skew-symmetric weight function matrices are used together with a generalized Betti's reciprocity theorem in order to derive a system of integral equations that relate the applied loading, the temperature and mass concentration fields, the heat and mass fluxes on the fracture surfaces and the resulting crack opening. The obtained integral identities can have many relevant applications, such as for the modelling of crack and damage processes at the interface between different components in electrochemical energy devices characterized by multi-layered structures (solid oxide fuel cells and lithium ions batteries).

  18. Rejuvenation and reuse of spent fluid cracking catalysts

    SciTech Connect (OSTI)

    Elvin, F.J. (ChemCat Corp., New Orleans, LA (US))

    1988-01-01

    Refineries processing heavy, high metals feedstocks have reused other refineries' spent cracking catalyst for the past ten years without observing any yield debits. ChemCat has developed a process whereby a refinery can reuse its own spent catalyst without suffering any yield debits. The new DEMET process is being demonstrated in the world's first commercial fluid cracking catalyst rejuvenation and demetallization plant. The plant is located in Meraux, Louisiana and processes 20 tons/day of spent cracking catalyst for local refineries. The plant removes contaminant metals from zeolite catalysts, while simultaneously increasingly the zeolite and matrix surface areas. The demetallized catalyst has a higher activity and better selectivity than the undemetallized spent catalyst. The demetallized catalyst is also more hydrothermally stable than the spent catalyst. ChemCat's DEMET process enables refiners to eliminate the high cost of spent FCCU catalyst disposal and to significantly reduce their consumption and cost of fresh catalyst.

  19. Method for fabrication of crack-free ceramic dielectric films

    DOE Patents [OSTI]

    Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

    2014-02-11

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  20. Relationships between stress corrosion cracking tests and utility operating experience

    SciTech Connect (OSTI)

    Baum, Allen

    1999-10-22

    Several utility steam generator and stress corrosion cracking databases are synthesized with the view of identifying the crevice chemistry that is most consistent with the plant cracking data. Superheated steam and neutral solution environments are found to be inconsistent with the large variations in the observed SCC between different plants, different support plates within a plant, and different crevice locations. While the eddy current response of laboratory tests performed with caustic chemistries approximates the response of the most extensively affected steam generator tubes, the crack propagation kinetics in these tests differ horn plant experience. The observations suggest that there is a gradual conversion of the environment responsible for most steam generator ODSCC from a concentrated, alkaline-forming solution to a progressively more steam-enriched environment.

  1. Optically controlled delays for broadband pulses 

    E-Print Network [OSTI]

    Sun, Q. Q.; Rostovtsev, Y. V.; Dowling, J. P.; Scully, Marlan O.; Zubairy, M. Suhail

    2005-01-01

    We propose a scheme that provides large controllable delays for broadband optical pulses. The system is based on the steep dispersion of a coherently driven medium, in which the narrow electromagnetically induced transparency (EIT) band is overcome...

  2. Optimal bandwidth allocation in a delay channel

    E-Print Network [OSTI]

    Ehsan, Navid; Liu, Mingyan

    2006-01-01

    following cost function: latest allocation will not make anyslot allocation problem, if the cost , then: function 1) forALLOCATION IN A DELAY CHANNEL If represents the value function

  3. Weld solidification cracking in 304 to 204L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-09-15

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  4. Weld solidification cracking in 304 to 304L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-01-01

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  5. Dynamic crack initiation toughness : experiments and peridynamic modeling.

    SciTech Connect (OSTI)

    Foster, John T.

    2009-10-01

    This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.

  6. Delaying the waterfall transition in warm hybrid inflation

    SciTech Connect (OSTI)

    Bastero-Gil, Mar [Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada, 18071 (Spain); Berera, Arjun; Metcalf, Thomas P. [SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ (United Kingdom); Rosa, João G., E-mail: mbg@ugr.es, E-mail: ab@ph.ed.ac.uk, E-mail: t.p.metcalf@ed.ac.uk, E-mail: joao.rosa@ua.pt [Departamento de Física da Universidade de Aveiro and I3N, Campus de Santiago, Aveiro, 3810-183 (Portugal)

    2014-03-01

    We analyze the dynamics and observational predictions of supersymmetric hybrid inflation in the warm regime, where dissipative effects are mediated by the waterfall fields and their subsequent decay into light degrees of freedom. This produces a quasi-thermal radiation bath with a slowly-varying temperature during inflation and further damps the inflaton's motion, thus prolonging inflation. As in the standard supercooled scenario, inflation ends when the waterfall fields become tachyonic and can no longer sustain a nearly constant vacuum energy, but the interaction with the radiation bath makes the waterfall fields effectively heavier and delays the phase transition to the supersymmetric minimum. In this work, we analyze for the first time the effects of finite temperature corrections and SUSY mass splittings on the quantum effective potential and the resulting dissipation coefficient. We show, in particular, that dissipation can significantly delay the onset of the tachyonic instability to yield 50–60 e-folds of inflation and an observationally consistent primordial spectrum, which is not possible in the standard supercooled regime when inflation is driven by radiative corrections.

  7. Synchronization of time delay systems using variable delay with reset for enhanced security in communication

    E-Print Network [OSTI]

    G. Ambika; R. E. Amritkar

    2010-07-01

    We have introduced a mechanism for synchronizing chaotic systems by one way coupling with a variable delay that is reset at finite intervals. Here we extend this method to time delay systems and suggest a new cryptosystem based on this. We present the stability analysis as applied to time delay systems and supplement this by numerical simulations in a standard time delay system like Mackey Glass system. We extend the theory to multi- delay systems and propose a bi channel scheme for the implementation of the scheme for communication with enhanced security. We show that since the synchronizing channel carries information from transmitter only at intervals of reset time, it is not susceptible to reconstruction. The message channel being separate can be made complex by linear combination of transmitter variable at different delay times using mutiple delay systems. This method has the additional advantage that it can be adjusted to be delay or anticipatory in synchronization and these provide two additional basic keys that are independent of system delay.

  8. Testing thermal reprocessing in AGN accretion discs

    E-Print Network [OSTI]

    E. M. Cackett; K. Horne; H. Winkler

    2007-06-11

    The thermal reprocessing hypothesis in AGN, where EUV/X-ray photons are reprocessed by the accretion disc into optical/UV photons, predicts wavelength-dependent time delays between the optical continuum at different wavelengths. Recent photometric monitoring by Sergeev et al. has shown that the time-delay is observed in 14 AGN, and generally seen to increase with increasing wavelength, as predicted in the reprocessing scenario. We fit the observed time delays and optical spectral energy distribution using a disc reprocessing model. The model delivers estimates for the nuclear reddening, the product of black hole mass times accretion rate, and the distance to each object. However, the distances at face value give H_0 = 44 +/- 5 km/s/Mpc - a factor of 1.6 smaller than generally accepted. We discuss the implications of this on the reprocessing model.

  9. Failure probability of axially cracked steam generator tubes; A probabilistic fracture mechanics model

    SciTech Connect (OSTI)

    Mavko, B.; Cizelj, L. (Jozef Stefan Inst., Reactor Engineering Div., P.O. Box 100, 61111 Ljubljana, Slovenia (YU))

    1992-05-01

    In this paper a model for estimating the failure probability of axially cracked steam generator tubes is proposed. The model compares observed crack length distribution with critical crack length distribution by means of probabilistic fracture mechanics. The observed crack length is influenced by measured data, measurement reliability, sizing accuracy, and predicted crack growth rate. The critical crack length is defined by a deterministic mechanical model. All cracks are conservatively assumed to extend through the tube wall. The effect of the plugging limit is studied along with the number of cracked tubes to perform risk-based lifetime optimization of steam generators. A numerical example presented considers hypothetical accidental operating conditions during a feedwater line break.

  10. The application of a logic framework for fatigue crack growth analyses to microstructural effects

    SciTech Connect (OSTI)

    Xu, J.G.; Liu, H.W.

    1995-12-31

    {Delta}K has been widely used to correlate da/dN data. The relation between da/dN and {Delta}K is usually found empirically. However, fatigue crack growth relations can also be derived theoretically. Three fatigue crack growth theories are derived for the state of small scale yielding and plane strain. These three theories constitute a logic framework useful for fatigue crack growth analyses. The application of the logic framework to the analyses of microstructural effects on fatigue crack growth is illustrated. The fatigue crack growth curve of 7075-T651 aluminum alloy has five distinct regions. A fatigue crack grows by crack-tip shear decohesion forming striations and by brittle fractures of particles followed by localized shear decohesion at these microcracks forming dimples. The logic framework helps to relate the fatigue crack growth behaviors in these five regions to the fractures of inclusions and to the resistance of grain boundaries and dispersoids to shear decohesion.

  11. Monitoring Cracking of a Smectitic Vertisol using Three-dimensional Electrical Resistivity Tomography 

    E-Print Network [OSTI]

    Ackerson, Jason Paul

    2013-11-20

    Upon desiccation, the matrix of Vertisols and other expansive soils shrinks. Matrix shrinkage results in the formation of cracks that can alter the hydrology of the soil. Despite the importance of cracks, many hydrologic models do not account...

  12. Numerical simulation of oxidation and its effect on the crack growth resistance of titanium alloys 

    E-Print Network [OSTI]

    Triharjanto, Robertus Heru

    1997-01-01

    though the oxidation generally degrades the MMC, the oxidation from the crack surfaces may improve the crack growth resistance of the metal matrix. Titanium alloys are potential candidates for use in MMC. Therefore, a more thorough understanding...

  13. Agglutination of single catalyst particles during fluid catalytic cracking as observed by X-ray nanotomography

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

    Meirer, F.; Kalirai, S.; Weker, J. Nelson; Liu, Y.; Andrews, J. C.; Weckhuysen, B. M.

    2015-04-14

    Metal accumulation at the catalyst particle surface plays a role in particle agglutination during fluid catalytic cracking.

  14. Dependence of dynamic fracture resistance on crack velocity in tungsten: Pt. II. Bicrystals and polycrystals

    SciTech Connect (OSTI)

    Liv, J.M.; Shen, B.W.

    1986-06-01

    The experimental techniques for crack velocity measurements have been applied to bicrystals of tungsten with twist orientations about (100) and polycrystals. The hesitation of the propagating cleavage crack in the vicinity of the grain boundary is examined. The contributions to energy dissipation from deformation and fracture processes in the grain boundary region as well as the in direct effects of crack deceleration are discussed. These findings have been applied to explain th dynamic fracture resistance and crack arrest in polycrystals.

  15. Incipient Crack Detection in Composite Wind Turbine Blades

    SciTech Connect (OSTI)

    Taylor, Stuart G. [Los Alamos National Laboratory; Choi, Mijin [Chonbuk National University, Korea; Jeong, Hyomi [Chonbuk National University, Korea; Jang, Jae Kyeong [Chonbuk National University, Korea; Park, Gyuhae [Chonnam National University, Korea; Farinholt, Kevin [Commonwealth Center for Advanced Manufacturing, VA; Farrar, Charles R. [Los Alamos National Laboratory; Ammerman, Curtt N. [Los Alamos National Laboratory; Todd, Michael D. [Los Alamos National Laboratory; Lee, Jung-Ryul [Chonbuk National University, Korea

    2012-08-28

    This paper presents some analysis results for incipient crack detection in a 9-meter CX-100 wind turbine blade that underwent fatigue loading to failure. The blade was manufactured to standard specifications, and it underwent harmonic excitation at its first resonance using a hydraulically-actuated excitation system until reaching catastrophic failure. This work investigates the ability of an ultrasonic guided wave approach to detect incipient damage prior to the surfacing of a visible, catastrophic crack. The blade was instrumented with piezoelectric transducers, which were used in an active, pitchcatch mode with guided waves over a range of excitation frequencies. The performance results in detecting incipient crack formation in the fiberglass skin of the blade is assessed over the range of frequencies in order to determine the point at which the incipient crack became detectable. Higher excitation frequencies provide consistent results for paths along the rotor blade's carbon fiber spar cap, but performance falls off with increasing excitation frequencies for paths off of the spar cap. Lower excitation frequencies provide more consistent performance across all sensor paths.

  16. CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR

    E-Print Network [OSTI]

    CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR James R. Rice* ABSTRACT An exact linear elastic-perfectly plastic solution is presented for the problem of a sharp notch coordinates corresponding to given stresses, position of the elastic-plastic boundary, and accompanying

  17. Thin film with oriented cracks on a flexible substrate

    DOE Patents [OSTI]

    Feng, Bao; McGilvray, Andrew; Shi, Bo

    2010-07-27

    A thermoelectric film is disclosed. The thermoelectric film includes a substrate that is substantially electrically non-conductive and flexible and a thermoelectric material that is deposited on at least one surface of the substrate. The thermoelectric film also includes multiple cracks oriented in a predetermined direction.

  18. Solvent control of crack dynamics in a reversible hydrogel

    E-Print Network [OSTI]

    Tristan Baumberger; Christiane Caroli; David Martina

    2006-05-16

    The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the cutting/slicing and eating characteristics of food gels. It is also critical for their utilization in tissue engineering, for which mechanical protection of encapsulated components is needed. Its dependence on loading rate and, recently, on the density and strength of cross-links has been investigated. But no attention was paid so far to solvent nor to environment effects. Here we report a systematic study of crack dynamics in gels of gelatin in water/glycerol mixtures. We show on this model system that: (i) increasing solvent viscosity slows down cracks; (ii) soaking with solvent increases markedly gel fragility; (iii) tuning the viscosity of the (miscible) environmental liquid affects crack propagation via diffusive invasion of the crack tip vicinity. The results point toward the fact that fracture occurs by viscoplastic chain pull-out. This mechanism, as well as the related phenomenology, should be common to all reversibly cross-linked (physical) gels.

  19. Method of making crack-free zirconium hydride

    DOE Patents [OSTI]

    Sullivan, Richard W. (Denver, CO)

    1980-01-01

    Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

  20. PENNY--SHAPED CRACK BRIDGED BY N.V. Movchan,

    E-Print Network [OSTI]

    Bath, University of

    PENNY--SHAPED CRACK BRIDGED BY FIBRES N.V. Movchan, School of Mathematical Sciences, University and Theoretical Physics, Silver Street, Cambridge, CB3 9EW, U.K. Abstract An axi--symmetric problem for a penny traction distribution. In the present paper we deal only with the second step, namely we consider a penny

  1. On the modeling of time-varying delays 

    E-Print Network [OSTI]

    Shah, Chirag Laxmikant

    2004-09-30

    This thesis is an effort to develop generalized dynamic models for systems with time-varying time delays. Unlike the simple time-delay model characterized by a transportation lag in the case of a fixed time delay, time-varying delays exhibit quite...

  2. 1. INTRODUCTION Current design methods focus on crack growth curves which are material properties for given

    E-Print Network [OSTI]

    Hively, Lee M.

    propagation. This technique has been demonstrated by test and analysis in fiberglass composite, aircraft fatigue, as well as Mode I low-temperature creep and stress corrosion. During the 1930s, A. A. Griffith sustained loading of cracks) and stress corrosion cracking (KI scc, JI scc, sustained loading of cracks

  3. Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D

    E-Print Network [OSTI]

    Zhou, Wei

    Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D W. Zhou*, T. Z. Long and C. K of the plates were produced using tungsten inert gas (TIG) welding method. The TIG arc was also used to deposit welding beads on some of the thin plates. No cracking was found in the butt joints. However, hot cracking

  4. Brittle film-induced cracking of ductile substrates , Lijie Qiao a,

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Brittle film-induced cracking of ductile substrates Tao Guo a , Lijie Qiao a, , Xiaolu Pang b 29 May 2015 Revised 22 July 2015 Accepted 23 July 2015 Keywords: Brittle film Ductile substrate Film-induced cracking Dislocations Crack velocity a b s t r a c t Film and substrate mechanical integrity is essential

  5. Mechanics and mechanisms of fatigue damage and crack growth in advanced materials

    E-Print Network [OSTI]

    Ritchie, Robert

    Mechanics and mechanisms of fatigue damage and crack growth in advanced materials R.O. Ritchie*, C 94720-1760, USA Abstract The mechanisms of fatigue-crack propagation in ceramics and intermetallics growth is considered to be a mutual competition between intrinsic mechanisms of crack advance ahead

  6. Permeability and elastic properties of cracked glass under pressure A. OugierSimonin,1

    E-Print Network [OSTI]

    Fortin, Jérôme

    for independent controls of the confining pressure, the axial stress, and pore pressure. We produced cracks with identified average aspect ratio and crack aperture, (2) a very small permeability which decreases as a power behavior of a cracked elastic brittle solid is reversible and independent of the fluid nature. Two

  7. A cracked beam finite element for rotating shaft dynamics and stability analysis

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    A cracked beam finite element for rotating shaft dynamics and stability analysis Saber El Arem Palaiseau, France Abstract In this paper, a method for the construction of a cracked beam finite element is presented. The additional flexibility due to the cracks is identified from three- dimensional finite element

  8. Automated Detection of Cracked Railway Axle Journals Using an Ultrasonic Phased Array Technique 

    E-Print Network [OSTI]

    Baik, Jaeyong

    2014-06-27

    ) automated detection system of a cracked axle journal using the ultrasonic phased array technique, 2) detection of a cracked axle journal using a chain scanner, and 3) cracked axle journal detection using surface waves. An ultrasonic phased array system has a...

  9. Fatigue-Crack Growth Behavior in the Superelastic and Shape-Memory Alloy Nitinol

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-Crack Growth Behavior in the Superelastic and Shape-Memory Alloy Nitinol A.L. McKELVEY and R.O. RITCHIE This article presents a study of fatigue-crack propagation behavior in Nitinol, a 50Ni, and constitutive behavior on crack-growth rates in NiTi.* NITINOL is a thermoelastic alloy with a composition

  10. A penny-shaped cohesive crack model for material damage G. Wang, S.F. Li *

    E-Print Network [OSTI]

    Li, Shaofan

    A penny-shaped cohesive crack model for material damage G. Wang, S.F. Li * Department of Civil solids with ran- domly distributed penny-shaped cohesive micro-cracks (Barenblatt­Dugdale type). Energy are derived based on homogenization of randomly distributed penny-shaped cohesive cracks (Barenblatt

  11. Crack Response to Blast Vibrations and Moisture Induced Volumetric Changes in Foundation Soils

    E-Print Network [OSTI]

    Crack Response to Blast Vibrations and Moisture Induced Volumetric Changes in Foundation Soils By C, Evanston, IL. Abstract In this paper vibratory crack response is compared to that produced by volumetric over a period of weeks to several months. On the other hand, crack response produced by volumetric

  12. Delay correlation analysis and representation for vital complaint VHDL models

    DOE Patents [OSTI]

    Rich, Marvin J.; Misra, Ashutosh

    2004-11-09

    A method and system unbind a rise/fall tuple of a VHDL generic variable and create rise time and fall time generics of each generic variable that are independent of each other. Then, according to a predetermined correlation policy, the method and system collect delay values in a VHDL standard delay file, sort the delay values, remove duplicate delay values, group the delay values into correlation sets, and output an analysis file. The correlation policy may include collecting all generic variables in a VHDL standard delay file, selecting each generic variable, and performing reductions on the set of delay values associated with each selected generic variable.

  13. Time-delayed feedback control of delay-coupled neurosystems and lasers

    E-Print Network [OSTI]

    Philipp Hövel; Markus A. Dahlem; Thomas Dahms; Gerald Hiller; Eckehard Schöll

    2009-12-17

    We discuss applications of time-delayed feedback control to delay-coupled neural systems and lasers, in the framework of the FitzHugh-Nagumo neuron model and the Lang-Kobayashi laser model, respectively. In the context of neural systems, we will point out some complex scenarios of synchronized in-phase or antiphase oscillations, bursting patterns, or amplitude death, induced by delayed coupling in combination with delayed self-feedback in simple network motifs. For optical systems, we will show that multiple time-delayed feedback, realized by a Fabry-Perot resonator coupled to the laser, provides a valuable tool for the suppression of unwanted intensity pulsations, and leads to stable continuous-wave operation.

  14. Delayed switching applied to memristor neural networks

    SciTech Connect (OSTI)

    Wang, Frank Z.; Yang Xiao; Lim Guan [Future Computing Group, School of Computing, University of Kent, Canterbury (United Kingdom); Helian Na [School of Computer Science, University of Hertfordshire, Hatfield (United Kingdom); Wu Sining [Xyratex, Havant (United Kingdom); Guo Yike [Department of Computing, Imperial College, London (United Kingdom); Rashid, Md Mamunur [CERN, Geneva (Switzerland)

    2012-04-01

    Magnetic flux and electric charge are linked in a memristor. We reported recently that a memristor has a peculiar effect in which the switching takes place with a time delay because a memristor possesses a certain inertia. This effect was named the ''delayed switching effect.'' In this work, we elaborate on the importance of delayed switching in a brain-like computer using memristor neural networks. The effect is used to control the switching of a memristor synapse between two neurons that fire together (the Hebbian rule). A theoretical formula is found, and the design is verified by a simulation. We have also built an experimental setup consisting of electronic memristive synapses and electronic neurons.

  15. Process for thermal hydrocracking of coal

    SciTech Connect (OSTI)

    Yamashita, K.; Kimura, M.

    1983-11-01

    A process for liquefying and gasifying coal by thermal treatment in the presence of hydrogen gas for hydrocracking is disclosed. The process comprises a sequence of the following two steps: (1) coal fines are injected into a heated hydrogen gas stream at a pressure of from 35 to 250 kg/cm G such that they are rapidly heated to a temperature of from 750/sup 0/ to 1100/sup 0/ C. for thermal cracking thereof; and (2) the resulting liquid product is subjected to hydrocracking for a period of from 1.0 to 60 seconds at a temperature that is lower than the temperature used in the first step and which is in the range of from 570/sup 0/ to 850/sup 0/ C.

  16. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    varying solar energy inputs and thermal or power demands. Itusing aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"

  17. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    of solar collectors and thermal energy storage in solaraided or powered by solar thermal energy. A section is alsobesides MVC require thermal energy as their primary energy

  18. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    15] O. A. Hamed, "THERMAL PERFORMANCE OF MULTISTAGE FLASHdesa4.aspx. [18] Encon, "Thermal Evaporators," June 2013. [http://www.evaporator.com/thermal-evaporator. [19] Y. Tian

  19. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    of such an aquifer thermal storage system were studied andusing aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"

  20. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    This requires no thermal storage tanks, but can have athe need for large thermal storage equipment, the evaporatorinclude analysis of thermal storage. A way of keeping the

  1. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    aquifers for thermal energy storage. Problems outlined aboveModeling of Thermal Energy Storage in Aquifers," Proceed-ings of Aquifer Thermal Energy Storage Workshop, Lawrence

  2. Modelling the microstructure of thermal barrier coatings

    SciTech Connect (OSTI)

    Cirolini, S.; Marchese, M.; Jacucci, G.; Harding, J.H.; Mulheran, P.A.

    1994-12-31

    Thermal barrier coatings produced by plasma spraying have a characteristic microstructure of lamellae, pores and cracks. The lamellae are produced by the splashing of particles onto the substrate. As the coating grows, the lamellae pile on top of each other, producing an interlocking structure. In most cases the growth is rapid and chaotic. The result is a microstructure characterized by pores and cracks. The authors present an improved model for the deposition process of thermal barrier coatings. The task of modeling the coating growth is split into two parts: first the authors consider a description of the particle on arrival at the film, based on the available theoretical, numerical and experimental findings. Second they define and discuss a set of physically-based rules for combining these events to obtain the film. The splats run along the surface and are permitted to curl up (producing pores) or interlock. The computer model uses a mesh to combine these processes and build the coating. They discuss the use of the proposed model in predicting microstructures and hence in correlating the properties of these coatings with the parameters of the process used to make them.

  3. Fatigue and Creep Crack Propagation behaviour of Alloy 617 in the Annealed and Aged Conditions

    SciTech Connect (OSTI)

    Julian K. Benz; Richard N. Wright

    2013-10-01

    The crack propagation behaviour of Alloy 617 was studied under various conditions. Elevated temperature fatigue and creep-fatigue crack growth experiments were conducted at 650 and 800 degrees C under constant stress intensity (triangle K) conditions and triangular or trapezoidal waveforms at various frequencies on as-received, aged, and carburized material. Environmental conditions included both laboratory air and characteristic VHTR impure helium. As-received Alloy 617 displayed an increase in the crack growth rate (da/dN) as the frequency was decreased in air which indicated a time-dependent contribution component in fatigue crack propagation. Material aged at 650°C did not display any influence on the fatigue crack growth rates nor the increasing trend of crack growth rate with decreasing frequency even though significant microstructural evolution, including y’ (Ni3Al) after short times, occurred during aging. In contrast, carburized Alloy 617 showed an increase in crack growth rates at all frequencies tested compared to the material in the standard annealed condition. Crack growth studies under quasi-constant K (i.e. creep) conditions were also completed at 650 degrees C and a stress intensity of K = 40 MPa9 (square root)m. The results indicate that crack growth is primarily intergranular and increased creep crack growth rates exist in the impure helium environment when compared to the results in laboratory air. Furthermore, the propagation rates (da/dt) continually increased for the duration of the creep crack growth either due to material aging or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 degrees C on annealed Alloy 617 indicated that crack propagation rates were higher in air than impure helium at the largest frequencies and lowest stress intensities. The rates in helium, however, eventually surpass the rates in air as the frequency is reduced and the stress intensity is decreased which was not observed at 650 degrees C.

  4. At-Speed Path Delay Test 

    E-Print Network [OSTI]

    Chakraborty, Swati

    2015-04-27

    This research describes an approach to test metastability of flip-flops with help of multiple at-speed capture cycles during delay test. K longest paths per flip-flop test patterns are generated, such that a long path on one clock cycle feeds a long...

  5. Penny-shaped and half-plane cracks in a transversely isotropic piezoelectric solid under arbitrary loading

    E-Print Network [OSTI]

    Sevostianov, Igor

    Penny-shaped and half-plane cracks in a transversely isotropic piezoelectric solid under arbitrary loading E. Karapetian, I. Sevostianov, M. Kachanov Summary The problem of a penny-shaped crack for a piezoelectric medium with a crack. Solutions for penny-shaped and half-plane cracks in an in®nite medium loaded

  6. Method for making dense crack free thin films

    DOE Patents [OSTI]

    Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

    2007-01-16

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  7. Methodology for predicting asphalt concrete overlay life against reflection cracking 

    E-Print Network [OSTI]

    Jayawickrama, Priyantha Warnasuriya

    1985-01-01

    METHODOLOGY FOR PREDICTING ASPHALT CONCRETE OVERLAY Lr 8 AGAINST REFLECTION CRACKING A Thesis by PRIYANTHA NARNASURIYA JAYAWICKRAMA Submitted to the Graduate College of Texas A8M University in Partial fulfillment of the requirements.... Experimental investigations carried out at Ohio State University ( 1, 2, 3) and Texas A8M University ( 4, 5, 6 ) have verified the applicability of fracture mechanics principles in predicting fatigue life of asphalt TIP OF THE CRACX /~ // N/i OVERLAY OLD...

  8. Catalytic cracking receives heavy attention at Q and A meeting

    SciTech Connect (OSTI)

    Not Available

    1993-04-19

    Refiners discussed fluid catalytic cracking (FCC) - the workhorse of the modern refinery - in great detail at the most recent National Petroleum Refiners Association's annual question and answer session on refining and petrochemical technology. Among the topics covered were the newest FCC refractory lining and particulate-control methods. The panel of experts also answered questions on the role of FCC in reducing gasoline benzene to meet reformulated gasoline specifications. This paper discusses refractories; particulate control; gasoline feeds; and benzene reduction.

  9. Crack growth monitoring in harsh environments by electrical potential measurements

    SciTech Connect (OSTI)

    W. R. Lloyd; W. G. Reuter; D. M. Weinberg

    1999-09-19

    Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique is applicable to many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed.

  10. Crack Growth Monitoring in Harsh Environments by Electric Potential Measurements

    SciTech Connect (OSTI)

    Lloyd, Wilson Randolph; Reuter, Walter Graham; Weinberg, David Michael

    1999-09-01

    Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique applicable is many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed.

  11. Advances in crack-arrest technology for reactor pressure vessels

    SciTech Connect (OSTI)

    Bass, B.R.; Pugh, C.E.

    1988-01-01

    The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the US Nuclear Regulatory Commission is continuing to improve the understanding of conditions that govern the initiation, rapid propagation, arrest, and ductile tearing of cracks in reactor pressure vessel (RPV) steels. This paper describes recent advances in a coordinated effort being conducted under the HSST Program by ORNL and several subcontracting groups to develop the crack-arrest data base and the analytical tools required to construct inelastic dynamic fracture models for RPV steels. Large-scale tests are being carried out to generate crack-arrest toughness data at temperatures approaching and above the onset of Charpy upper-shelf behavior. Small- and intermediate-size specimens subjected to static and dynamic loading are being developed and tested to provide additional fracture data for RPV steels. Viscoplastic effects are being included in dynamic fracture models and computer programs and their utility validated through analyses of data from carefully controlled experiments. Recent studies are described that examine convergence problems associated with energy-based fracture parameters in viscoplastic-dynamic fracture applications. Alternative techniques that have potential for achieving convergent solutions for fracture parameters in the context of viscoplastic-dynamic models are discussed. 46 refs., 15 figs., 3 tabs.

  12. To Crack or Not to Crack: Strain in High TemperatureSuperconductors

    SciTech Connect (OSTI)

    Godeke, Arno

    2007-08-22

    Round wire Bi 2212 is emerging as a viable successor ofNb3Sn in High Energy Physics and Nuclear Magnetic Resonance, to generatemagnetic fields that surpass the intrinsic limitations of Nb3Sn. Ratherbold claims are made on achievable magnetic fields in applications usingBi 2212, due to the materials' estimated critical magnetic field of 100 Tor higher. High transport currents in high magnetic fields, however, leadto large stress on, and resulting large strain in the superconductor. Theeffect of strain on the critical properties of Bi-2212 is far fromunderstood, and strain is, as with Nb3Sn, often treated as a secondaryparameter in the design of superconducting magnets. Reversibility of thestrain induced change of the critical surface of Nb3Sn, points to anelectronic origin of the observed strain dependence. Record breaking highfield magnets are enabled by virtue of such reversible behavior. Straineffects on the critical surface of Bi-2212, in contrast, are mainlyirreversible and suggest a non-electronic origin of the observed straindependence, which appears to be dominated by the formation of cracks inthe superconductor volumes. A review is presented of available results onthe effects of strain on the critical surface of Bi-2212, Bi-2223 andYBCO. It is shown how a generic behavior emerges for the (axial) straindependence of the critical current density, and how the irreversiblereduction of the critical current density is dominated by strain inducedcrack formation in the superconductor. From this generic model it becomesclear that magnets using high temperature superconductors will be strainlimited far before the intrinsic magnetic field limitations will beapproached, or possibly even before the magnetic field limitation ofNb3Sn can be surpassed. On a positive note, in a very promising recentresult from NIST on the axial strain dependence of the critical currentdensity in extremely well aligned YBCO, reversible behavior was observed.This result emphasizes the need for further conductor development,specifically for round wire Bi-2212, to generate a wire with a similarreversible dependence on strain. Availability of such a wire will enablethe construction of magnets that can indeed generate fields that farsurpass the limitations of Nb3Sn superconductors.

  13. Asphalt overlay design methods for rigid pavements considering rutting, reflection cracking, and fatigue cracking. Research report September 1996--August 1997

    SciTech Connect (OSTI)

    Cho, Y.H.; Liu, C.; Dossey, T.; McCullough, B.F.

    1998-10-01

    An asphalt concrete pavement (ACP) overlay over a rigid pavement represents a viable rehabilitation strategy. It can provide good serviceability at an initial construction cost that is substantially less than that of a rigid overlay rehabilitation. In addition, ACP overlays require less construction time, which can reduce user costs during construction. However, it may not be the most economical solution for long-term rehabilitation. Because of their relatively short service life, ACP overlays may require maintenance sooner than rigid overlays. And one of the more critical distresses that effectively determine the life span of the structure is reflection cracking. This report investigates alternative strategies that seek to prevent reflection cracking on ACP overlays.

  14. Thermal Transport in Nanoporous Materials for Energy Applications

    E-Print Network [OSTI]

    Fang, Jin

    2012-01-01

    Thermal Conductivity Measurement . . . . . . . . . . . . .Thermal ConductivityThermal Conductivity . . . . . . . . . . . . . . . .Thermal

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

    E-Print Network [OSTI]

    Tamilarasan, Karthik Prabhu

    2012-02-14

    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 ...

  16. Adapting a delay-based protocol to heterogeneous environments 

    E-Print Network [OSTI]

    Kotla, Kiran

    2008-10-10

    We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We ...

  17. Analysis of AIMD protocols over paths with variable delay

    E-Print Network [OSTI]

    . The distribution of delays for these systems is de- scribed in [13]. HDR is a Qualcomm proposed CDMA air interface

  18. Time delay measurement in the frequency domain

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

    Durbin, Stephen M.; Liu, Shih -Chieh; Dufresne, Eric M.; Li, Yuelin; Wen, Haidan

    2015-08-06

    Pump–probe studies at synchrotrons using X-ray and laser pulses require accurate determination of the time delay between pulses. This becomes especially important when observing ultrafast responses with lifetimes approaching or even less than the X-ray pulse duration (~100 ps). The standard approach of inspecting the time response of a detector sensitive to both types of pulses can have limitations due to dissimilar pulse profiles and other experimental factors. Here, a simple alternative is presented, where the frequency response of the detector is monitored versus time delay. Measurements readily demonstrate a time resolution of ~1 ps. Improved precision is possible bymore »simply extending the data acquisition time.« less

  19. Synchronization phenomena for coupled delay-line oscillators

    E-Print Network [OSTI]

    Chicone, Carmen

    F@missouri.edu. 1 #12;1 Introduction Delay equation models for surface acoustic wave (SAW) delay-line devices-built surface acoustic wave (SAW) delay-line oscillators is examined. A bifurcation analysis reveals, averaging, Hopf bifurca- tion, Surface acoustic waves. AMS Classification: 34K60 Corresponding author

  20. Power and Delay Optimization in Multi-Hop Wireless Networks

    E-Print Network [OSTI]

    Shihada, Basem

    In this paper, we study the optimization problem of transmission power and delay in a multi-hop wireless network of transmission power and queueing delay in wireless networks has1 Power and Delay Optimization in Multi-Hop Wireless Networks Li Xia, Basem Shihada Abstract

  1. Fault modeling, delay evaluation and path selection for delay test under process variation in nano-scale VLSI circuits 

    E-Print Network [OSTI]

    Lu, Xiang

    2006-04-12

    Delay test in nano-scale VLSI circuits becomes more difficult with shrinking technology feature sizes and rising clock frequencies. In this dissertation, we study three challenging issues in delay test: fault modeling, ...

  2. Dependence of dynamic fracture resistance on crack velocity in tungsten: Pt. 1. Single crystals

    SciTech Connect (OSTI)

    Liv, J.M.; Shen, B.W.

    1984-06-01

    The dependence of dynamic fracture resistance on crack propagation velocity on (100) in tungsten has been examined. A correlation is obtained between the measured local crack velocity with the surfac and subsurface deformations. Based on the experimental results on one pass, two passes, and prestrained, electron beam zone refined single crystals, a discussion is given on the slip modes activated at the crack tip, the contributions to the dynamic fracture resistance from dislocations and surface features and from the preexisting deformed microstructure.

  3. Three-dimensional EBSD characterization of thermo-mechanical fatigue crack morphology in compacted graphite iron

    SciTech Connect (OSTI)

    Pirgazi, Hadi, E-mail: Hadi.pirgazi@ugent.be [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, 9052 Gent (Belgium); Ghodrat, Sepideh, E-mail: s.ghodrat@tudelft.nl [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft (Netherlands); Kestens, Leo A.I., E-mail: leo.kestens@ugent.be [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, 9052 Gent (Belgium); Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft (Netherlands)

    2014-04-01

    In cylinder heads made of compacted graphitic iron (CGI), heating and cooling cycles can lead to localized cracking due to thermo-mechanical fatigue (TMF). To meticulously characterize the complex crack path morphology of CGI under TMF condition, in relation to microstructural features and to find out how and by which mechanisms the cracks predominantly develop, three-dimensional electron back scattering diffraction (EBSD) was employed. Based on the precise quantitative microstructural analysis, it is found that graphite particles not only play a crucial role in the crack initiation, but also are of primary significance for crack propagation, i.e. crack growth is enhanced by the presence of graphite particles. Furthermore, the density of graphite particles on the fracture plane is more than double as high as in any other arbitrary plane of the structure. The obtained results did not indicate a particular crystallographic preference of fracture plane, i.e. the crystal plane parallel to the fracture plane was nearly of random orientation. - Highlights: • Crystallographic features of a thermo-mechanical fatigue (TMF) crack were studied. • Wide-field 3D EBSD is used to characterize the TMF crack morphology. • Data processing was applied on a large length scale of the order of millimeters. • Graphite density in the fracture plane is much higher than any other random plane. • It is revealed that crack growth is enhanced by the presence of graphite particles.

  4. J-integral for a semi-elliptical surface crack at a bimaterial interface

    SciTech Connect (OSTI)

    Sharobeam, M.H.; Landes, J.D.

    1995-12-31

    Surface cracks are common defects in welded, bonded, and composite structures. The elastic-plastic fracture of these defects may be analyzed using the J-integral. The authors have recently developed a new approach to evaluate the J-integral for semi-elliptical surface cracks in panels made of homogeneous materials and subject to remote tension. This approach, which is based on load separation, allows the evaluation of J for such a three-dimensional geometry using a single specimen test record. It is analogous to the single specimen technique in two-dimensional geometries. In this article, the authors extend their study to surface cracks at bimaterial interfaces. A three-dimensional finite element model is developed to model such a crack. The J-integral is evaluated along the crack front using the virtual crack extension method. The elastic-plastic fracture behavior of the crack is studied. Load separation is also examined and the new single specimen approach for surface cracks in single material panels is extended to those at bimaterial interfaces. The study also includes a comparison between the results of surface cracks in single material panels and those at bimaterial interfaces.

  5. Simulation of the ultrasonic array response from real branched cracks using an efficient finite element method

    SciTech Connect (OSTI)

    Felice, Maria V. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom and Rolls-Royce plc., Bristol BS34 7QE (United Kingdom); Velichko, Alexander; Wilcox, Paul D. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Barden, Tim J.; Dunhill, Tony K. [Rolls-Royce plc., Bristol BS34 7QE (United Kingdom)

    2014-02-18

    A hybrid model to simulate the ultrasonic array response from stress corrosion cracks is presented. These cracks are branched and difficult to detect so the model is required to enable optimization of an array design. An efficient frequency-domain finite element method is described and selected to simulate the ultrasonic scattering. Experimental validation results are presented, followed by an example of the simulated ultrasonic array response from a real stress corrosion crack whose geometry is obtained from an X-ray Computed Tomography image. A simulation-assisted array design methodology, which includes the model and use of real crack geometries, is proposed.

  6. Standard test method for measurement of creep crack growth times in metals

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This test method covers the determination of creep crack growth (CCG) in metals at elevated temperatures using pre-cracked specimens subjected to static or quasi-static loading conditions. The time (CCI), t0.2 to an initial crack extension ?ai = 0.2 mm from the onset of first applied force and creep crack growth rate, ?a or da/dt is expressed in terms of the magnitude of creep crack growth relating parameters, C* or K. With C* defined as the steady state determination of the crack tip stresses derived in principal from C*(t) and Ct (1-14). The crack growth derived in this manner is identified as a material property which can be used in modeling and life assessment methods (15-25). 1.1.1 The choice of the crack growth correlating parameter C*, C*(t), Ct, or K depends on the material creep properties, geometry and size of the specimen. Two types of material behavior are generally observed during creep crack growth tests; creep-ductile (1-14) and creep-brittle (26-37). In creep ductile materials, where cr...

  7. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    SciTech Connect (OSTI)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K[sub ISCC], crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  8. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    SciTech Connect (OSTI)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K{sub ISCC}, crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  9. Innovative Approach to Establish Root Causes for Cracking in Aggressive Reactor Environments

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Thomas, Larry E.; Vetrano, John S.; Simonen, Edward P.

    2003-10-31

    The research focuses on the high-resolution characterization of degradation microstructures and microchemistries in specimens tested under controlled conditions for the environment and for the material where in-service complexities can be minimized. Thermodynamic and kinetic modeling of crack-tip processes is employed to analyze corrosion-induced structures and gain insights into degradation mechanisms. Novel mechanistic ''fingerprinting'' of crack-tip structures is used to isolate causes of environmental cracking in tandem with quantitative measurements of crack growth. Sample preparation methods and advanced analytical techniques are used to characterize corrosion/oxidation reactions and crack-tip structures at near atomic dimensions in order to gain insight into fundamental environmental cracking mechanisms. Reactions at buried interfaces, not accessible by conventional approaches, are being systematically interrogated. Crack-growth experiments in high-temperature water environments are evaluating and isolating the effects of material condition (matrix strength, grain boundary composition and precipitation) on stress corrosion cracking (SCC). The fundamental understanding of crack advance mechanisms will establish the basis to design new corrosion-resistant alloys for current light-water reactors and advanced reactor systems.

  10. Scaling of Lyapunov exponents in chaotic delay systems

    E-Print Network [OSTI]

    Thomas Jüngling; Wolfgang Kinzel

    2012-10-12

    The scaling behavior of the maximal Lyapunov exponent in chaotic systems with time-delayed feedback is investigated. For large delay times it has been shown that the delay-dependence of the exponent allows a distinction between strong and weak chaos, which are the analogy to strong and weak instability of periodic orbits in a delay system. We find significant differences between scaling of exponents in periodic or chaotic systems. We show that chaotic scaling is related to fluctuations in the linearized equations of motion. A linear delay system including multiplicative noise shows the same properties as the deterministic chaotic systems.

  11. Investigation of cracking and leaking of nuclear reactor pools 

    E-Print Network [OSTI]

    Cooper, William Bernard

    1965-01-01

    . Typical Gage Points on Pool Wall 12 8. s, . Locations of Leakage b. Locations of Leakage c. Locations of Leakage 13 14 15 9 ~ Structural Model 10. Creep Test 11. Shrinkage of Various Concrete Specimens (Dry ), 12. Permeability Test 16 26 28...'LLCS H. ~ Typi cB1 LCBkage T)n Q13gi'I th 8 PQol Wall ~ ln 196Q~ ax attempt was made to control tbe leakage by grani, in~ =". lean cemert, mix Under' high pressure into the cracks in tbe concrete pool vail in. an attempt, to fill the existing voids...

  12. On the approximation of crack shapes found during inservice inspection

    SciTech Connect (OSTI)

    Bhate, S.R.; Chawla, D.S.; Kushwaha, H.S. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    This paper addresses the characterization of axial internal flaw found during inservice inspection of a pipe. J-integral distribution for various flaw shapes is obtained using line spring finite, element method. The peak J-value and its distribution across the crack is found to be characteristic feature of each shape. The triangular shape yields peak J-value away from the center, the point of depth. The elliptic approximation results in large overestimate of J-value for unsymmetric flaws. Triangular approximation is recommended for such flaws so that further service can be obtained from the component.

  13. A Feedback-based Adaptive Broadcast Coding Scheme for Reducing In-order Delivery Delay

    E-Print Network [OSTI]

    Medard, Muriel

    We propose a new feedback-based adaptive coding scheme for a packet erasure broadcast channel. The main performance metric of interest is the delay. We consider two types of delay - decoding delay and delivery delay. ...

  14. High Temperature Thermal Array for Next Generation Solar Thermal...

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

    High Temperature Thermal Array for Next Generation Solar Thermal Power Production High Temperature Thermal Array for Next Generation Solar Thermal Power Production This...

  15. Delayed Fission Gamma-ray Characteristics of Th-232 U-233 U-235 U-238 and Pu-239

    SciTech Connect (OSTI)

    Lane, Taylor; Parma, Edward J.

    2015-08-01

    Delayed fission gamma-rays play an important role in determining the time dependent ioniz- ing dose for experiments in the central irradiation cavity of the Annular Core Research Reactor (ACRR). Delayed gamma-rays are produced from both fission product decay and from acti- vation of materials in the core, such as cladding and support structures. Knowing both the delayed gamma-ray emission rate and the time-dependent gamma-ray energy spectrum is nec- essary in order to properly determine the dose contributions from delayed fission gamma-rays. This information is especially important when attempting to deconvolute the time-dependent neutron, prompt gamma-ray, and delayed gamma-ray contribution to the response of a diamond photo-conducting diode (PCD) or fission chamber in time frames of milliseconds to seconds following a reactor pulse. This work focused on investigating delayed gamma-ray character- istics produced from fission products from thermal, fast, and high energy fission of Th-232, U-233, U-235, U-238, and Pu-239. This work uses a modified version of CINDER2008, a transmutation code developed at Los Alamos National Laboratory, to model time and energy dependent photon characteristics due to fission. This modified code adds the capability to track photon-induced transmutations, photo-fission, and the subsequent radiation caused by fission products due to photo-fission. The data is compared against previous work done with SNL- modified CINDER2008 [ 1 ] and experimental data [ 2 , 3 ] and other published literature, includ- ing ENDF/B-VII.1 [ 4 ]. The ability to produce a high-fidelity (7,428 group) energy-dependent photon fluence at various times post-fission can improve the delayed photon characterization for radiation effects tests at research reactors, as well as other applications.

  16. Effects of thermal fluctuations on thermal inflation

    E-Print Network [OSTI]

    Takashi Hiramatsu; Yuhei Miyamoto; Jun'ichi Yokoyama

    2014-12-25

    The mechanism of thermal inflation, a relatively short period of accelerated expansion after primordial inflation, is a desirable ingredient for a certain class of particle physics models if they are not to be in contention with the cosmology of the early Universe. Though thermal inflation is most simply described in terms of a thermal effective potential, a thermal environment also gives rise to thermal fluctuations that must be taken into account. We numerically study the effects of these thermal fluctuations using lattice simulations. We conclude that though they do not ruin the thermal inflation scenario, the phase transition at the end of thermal inflation proceeds through phase mixing and is therefore not accompanied by the formations of bubbles nor appreciable amplitude of gravitational waves.

  17. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    storage in solar thermal applications," Applied Energy, pp.of Non-Tracking Solar Thermal Technology," 2011. [26] R.C. Y. Zhao, "A review of solar collectors and thermal energy

  18. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    Evaporator Powered By Solar Thermal Energy 10:00 AM 10:00 AMaided or powered by solar thermal energy. A section is alsoexhaustive review of solar thermal energy systems has been

  19. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    and thermal energy storage in solar thermal applications,"Solar infrastructure should include analysis of thermal storage.storage equipment, the evaporator can be integrated into the current solar

  20. Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks: Shrinkage-Reducing Admixtures, Internal Curing, and Cracking Performance

    E-Print Network [OSTI]

    Pendergrass, Ben Andrew

    2014-05-31

    ABSTRACT The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks is described based on laboratory tests of mixtures containing shrinkage-reducing admixtures and mineral admixtures in conjunction...

  1. Modeling dynamic crack propagation in fiber reinforced composites including frictional effects q

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Modeling dynamic crack propagation in fiber reinforced composites including frictional effects q S Abstract Dynamic crack propagation in a unidirectional carbon/epoxy composite is studied through finite deformation anisotropic visco-plastic model is used to describe the constitutive response of the composite

  2. Cracks in martensite plates as hydrogen traps in a bearing steel

    E-Print Network [OSTI]

    Cambridge, University of

    Cracks in martensite plates as hydrogen traps in a bearing steel W. Solano-Alvareza , Eun Ju Songb stability requirements, and to improve the properties of the martensite [1]. Like most strong steels It is demonstrated that a macroscopically homogeneous distribution of tiny cracks introduced into a martensitic

  3. Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda)

    E-Print Network [OSTI]

    Bowler, John R.

    Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda) and J. R. Bowler; accepted for publication 14 July 1997 Eddy-current non-destructive evaluation is commonly performed of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields

  4. Non-hypersingular boundary integral equations for 3-D non-planar crack dynamics

    E-Print Network [OSTI]

    Madariaga, Raúl

    Non-hypersingular boundary integral equations for 3-D non-planar crack dynamics T. Tada, E, are removed by way of a technique of regu- larization based on integration by parts. The variables are denoted, in time and space, of the slip along the crack and a set of integration kernels. Then a limiting process

  5. THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice*

    E-Print Network [OSTI]

    THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice* ABSTRACT This paper briefly reviews progres~in the elastic plastic analysisof crack extension. Analytical results for plane strain and plane stress deformation fields are noted, and elastic-plastic fracture instability as well as transitional

  6. Mixed Mode Static and Fatigue Crack Growth in Wind Blade Paste Adhesives

    E-Print Network [OSTI]

    1 Mixed Mode Static and Fatigue Crack Growth in Wind Blade Paste Adhesives Daniel D. Samborsky, static GIc and mixed mode fracture, and fatigue crack growth resistance. I. Introduction Wind turbine, then adhesively bonded together. The large size coupled with cost constraints result in bond lines at least

  7. THE DYNAMICS OF RAPIDLY MOVING TENSILE CRACKS IN BRITTLE AMORPHOUS MATERIAL

    E-Print Network [OSTI]

    Fineberg, Jay

    initiated during the second World War. These theories generalized the concept of energy balance, which, and a corresponding sharp increase of the fracture energy with the mean crack velocity. We present experimental occurs when the potential elastic energy per unit area released by a unit extension of a crack is equal

  8. Robust damage assessment of multiple cracks based on the Frequency Response Function and the Constitutive Relation

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Robust damage assessment of multiple cracks based on the Frequency Response Function a damage assessment technique for the non destructive detection and sizing of multiple open cracks in beams, many researchers have performed extensive investigations and damage assess- ment techniques based

  9. Assessing Hydrogen-Assisted Cracking Fracture Modes in High-Strength

    E-Print Network [OSTI]

    Eagar, Thomas W.

    I I Ii . I f. Assessing Hydrogen-Assisted Cracking Fracture Modes in High-Strength Steel Weldments Test results substantiate and extend the Beachem theory on hydrogen embrittlement ABSTRACT of the hydrogen content at the crack loca- tion. This relationship was used to assess previously proposed

  10. Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and

    E-Print Network [OSTI]

    Ritchie, Robert

    Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows

  11. Brittle fracture in a periodic structure with internal potential energy. Spontaneous crack propagation

    E-Print Network [OSTI]

    Mark Ayzenberg-Stepanenko; Gennady Mishuris; Leonid Slepyan

    2014-02-12

    Spontaneous brittle fracture is studied based on the recently introduced model (Mishuris and Slepyan, Brittle fracture in a periodic structure with internal potential energy. Proc. Roy. Soc. A, in press). A periodic structure is considered, where only the prospective crack-path layer is specified as a discrete set of alternating initially stretched and compressed bonds. A bridged crack destroying initially stretched bonds may propagate under a certain level of the internal energy without external sources. The general analytical solution with the crack speed $-$ energy relation is presented in terms of the crack-related dynamic Green's function. For the anisotropic two-line chain and lattice considered earlier in quasi-statics, the dynamic problem is examined in detail. The crack speed is found to grow unboundedly as the energy approaches its upper limit. It is revealed that the spontaneous fracture can occur in the form of a pure bridged, partially bridged or fully open crack depending on the internal energy level. Generally, the steady-state mode of the crack propagation is found to be realised, whereas an irregular growth, clustering and the crack speed oscillations are detected in a vicinity of the lower bound of the energy.

  12. A stochastic model of fatigue crack propagation under variable-amplitude loading

    E-Print Network [OSTI]

    Ray, Asok

    -space model of fatigue crack propagation under variable-amplitude loading. The (non-stationary) statistic. Introduction Fatigue crack analysis is an essential tool for life prediction and maintenance of machinery/strain) factor b a constant model parameter larger than 1 (I 10) d increment operator DS eective stress range W 2

  13. Comparing Methods of Estimating Crack Volume in Shrink-Swell Soils 

    E-Print Network [OSTI]

    Rivera, Leonardo D.

    2011-08-04

    were measured on both soils. Vertical subsidence was measured at three locations in each soil with rods fixed at four depths. Rod movement was converted to soil crack volume by assuming equi-dimensional shrinkage. A second method for estimating crack...

  14. 3D MULTIPLE CRACK SYSTEM: EXTRACTION AND ANALYSIS USING MOTION-BASED IMAGE PROCESSING TECHNIQUE

    E-Print Network [OSTI]

    Nagy, George

    , including the number of cracks, surface area, volume, tortuosity, and permeability. Keywords: X-ray microtomography, image processing, concrete fracture. INTRODUCTION We examine the crack surfaces of concrete the fracture behavior of concrete, they have been ignored because "understanding of this problem

  15. The roles of toughness and cohesive strength on crack deflection at

    E-Print Network [OSTI]

    Thouless, Michael

    composite systems. Brittle materials such as ceramics, concrete or epoxies can be toughened by the addition & Engineering University of Michigan Ann Arbor, MI 48109 August 30, 2005 Abstract In order to design composites and the matrix. If crack deflection does not occur, a crack propagating through the matrix will continue

  16. Fatigue-crack propagation in Nitinol, a shape-memory and superelastic endovascular stent material

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-crack propagation in Nitinol, a shape-memory and superelastic endovascular stent material A Nitinol. Specifically, the objective of this work was to study the effect of environ- ment on cyclic crack of Nitinol endovascular stents. The material selected for this study was heat treated

  17. Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

    E-Print Network [OSTI]

    Ritchie, Robert

    Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites M. E of cracks, such as tensile ductil- ity, toughness, and fatigue resistance, can become severely compromised macroscopic ductility,3,4 such that the toughness is far lower than in comparable crystalline alloys

  18. Technical Note Fiducial marks as measures of thin film crack arrest toughness

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Technical Note Fiducial marks as measures of thin film crack arrest toughness Alex A. Volinsky a Published by Elsevier Science Ltd. Keywords: Fiducial marks; Adhesion; Fracture; Delamination; Crack arrest). This technique was shown to work with ductile metallic films (Al, Cu, Au, Cr) [2,4­9,15], ceramic (Ta2N) [10

  19. EFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS

    E-Print Network [OSTI]

    Ritchie, Robert

    EFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS AT ELEVATED crack under cyclic loading conditions at elevated temperatures in high-toughness, monolithic ceramics the frequency and temperature sensitivity not gen- erally observed in ceramics at room temperature. Solutions

  20. Channel cracks in a hermetic coating consisting of organic and inorganic layers

    E-Print Network [OSTI]

    Suo, Zhigang

    Channel cracks in a hermetic coating consisting of organic and inorganic layers Nicolas Cordero 2007 Flexible electronic devices often require hermetic coatings that can withstand applied strains. This letter calculates the critical strains for various configurations of channel cracks in a coating

  1. Effect of elastic coating on fracture behaviour of piezoelectric fibre with a penny-shaped crack

    E-Print Network [OSTI]

    Qin, Qinghua

    Effect of elastic coating on fracture behaviour of piezoelectric fibre with a penny-shaped crack, Tianjin University, Tianjin 300072, China Abstract In this paper, the problem of a penny-shaped crack of piezoelectric fibre composites. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Piezoelectric fibre; Penny

  2. Thermal Control & System Integration

    Broader source: Energy.gov [DOE]

    The thermal control and system integration activity focuses on issues such as the integration of motor and power control technologies and the development of advanced thermal control technologies....

  3. DNA Engine Thermal Cycler

    E-Print Network [OSTI]

    Raizada, Manish N.

    ® Peltier Thermal Cycler PTC-0200 DNA Engine Cycler Operations Manual Version 4.0 #12;ii Tech Support: 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vi The DNA Engine® Peltier Thermal Cycler Introduction

  4. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    and C. Y. Zhao, "A review of solar collectors and thermalenergy storage in solar thermal applications," Appliedon photovoltaic/thermal hybrid solar technology," Applied

  5. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    thermal energy becomes apparent with the development of solarsolar energy systems, aquifer energy storage provides a buffer between time-varying solar energy inputs and thermal

  6. Fatigue crack propagation in a quasi one-dimensional elasto-plastic model

    E-Print Network [OSTI]

    Tomás M. Guozden; Eduardo A. Jagla

    2012-06-27

    Fatigue crack advance induced by the application of cyclic quasistatic loads is investigated both numerically and analytically using a lattice spring model. The system has a quasi-one-dimensional geometry, and consists in two symmetrical chains that are pulled apart, thus breaking springs which connect them, and producing the advance of a crack. Quasistatic crack advance occurs as a consequence of the plasticity included in the springs which form the chains, and that implies a history dependent stress-strain curve for each spring. The continuous limit of the model allows a detailed analytical treatment that gives physical insight of the propagation mechanism. This simple model captures key features that cause well known phenomenology in fatigue crack propagation, in particular a Paris-like law of crack advance under cyclic loading, and the overload retardation effect.

  7. Thermal barrier coating resistant to sintering

    DOE Patents [OSTI]

    Subramanian, Ramesh; Seth, Brig B.

    2005-08-23

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process. The sintering inhibiting material (22) has a morphology adapted to improve the functionality of the sintering inhibiting material (22), characterized as continuous, nodule, rivulet, grain, crack, flake and combinations thereof and being disposed within at least some of the vertical and horizontal gaps.

  8. Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical crack growth, and some implications

    E-Print Network [OSTI]

    crack growth, and some implications for rock engineering R.A. Schultz* Geomechanics-Rock Fracture Group

  9. Mean field approximation for noisy delay coupled excitable neurons

    E-Print Network [OSTI]

    Nikola Buric; Dragana Rankovic; Kristina Todorovic; Nebojsa Vasovic

    2010-03-26

    Mean field approximation of a large collection of FitzHugh-Nagumo excitable neurons with noise and all-to-all coupling with explicit time-delays, modelled by $N\\gg 1$ stochastic delay-differential equations is derived. The resulting approximation contains only two deterministic delay-differential equations but provides excellent predictions concerning the stability and bifurcations of the averaged global variables of the exact large system.

  10. Review of industry efforts to manage pressurized water reactor feedwater nozzle, piping, and feedring cracking and wall thinning

    SciTech Connect (OSTI)

    Shah, V.N.; Ware, A.G.; Porter, A.M.

    1997-03-01

    This report presents a review of nuclear industry efforts to manage thermal fatigue, flow-accelerated corrosion, and water hammer damage to pressurized water reactor (PWR) feedwater nozzles, piping, and feedrings. The review includes an evaluation of design modifications, operating procedure changes, augmented inspection and monitoring programs, and mitigation, repair and replacement activities. Four actions were taken: (a) review of field experience to identify trends of operating events, (b) review of technical literature, (c) visits to PWR plants and a PWR vendor, and (d) solicitation of information from 8 other countries. Assessment of field experience is that licensees have apparently taken sufficient action to minimize feedwater nozzle cracking caused by thermal fatigue and wall thinning of J-tubes and feedwater piping. Specific industry actions to minimize the wall-thinning in feedrings and thermal sleeves were not found, but visual inspection and necessary repairs are being performed. Assessment of field experience indicates that licensees have taken sufficient action to minimize steam generator water hammer in both top-feed and preheat steam generators. Industry efforts to minimize multiple check valve failures that have allowed backflow of steam from a steam generator and have played a major role in several steam generator water hammer events were not evaluated. A major finding of this review is that analysis, inspection, monitoring, mitigation, and replacement techniques have been developed for managing thermal fatigue and flow-accelerated corrosion damage to feedwater nozzles, piping, and feedrings. Adequate training and appropriate applications of these techniques would ensure effective management of this damage.

  11. Model of crack propagation in a clay soil 

    E-Print Network [OSTI]

    Carriere, Patrick Edwidge

    1985-01-01

    of variance (ANOVA) to obtain the best selection to be included in the model. The ANOYA model was expressed by: Model = BO(H) + Bl(CL) + B2(M) + B3(H"M) + B4(H*CL) + B5(M*CL) + B6(H~M*CL) where: H = humidity effect, CL = clay content effect, M = initial.... 0280* T5 0. 7413 0. 5771 6. 16 0. 0001* T6 0. 2973 0. 2887 4. 94 0. 001* T7 0. 2065 0. 3432 2. 89 0. 0084* T8 0. 2543 0. 0767 15. 89 0. 0001* * significant at level 0. 05 30 Table 3. ANOVA results for crack de th. Source Sum of Degrees of Mean F...

  12. Specified pipe fittings susceptible to sulfide stress cracking

    SciTech Connect (OSTI)

    McIntyre, D.R.; Moore, E.M. Jr. [Saudi Aramco, Dhahran (Saudi Arabia)

    1996-01-01

    The NACE Standard MR0175 limit of HRC 22 is too high for cold-forged and stress-relieved ASTM A234 WPB pipe fittings. Hardness surveys and sulfide stress cracking test results per ASTM G 39 and NACE TM0177 Method B are presented to support this contention. More stringent inspection and a hardness limit of HB 197 (for cold-forged and stress-relieved fittings only) are recommended. The paper describes a case in which fittings were welded in place in wet sour service flow lines and gas-oil separating plants which were ready to start. The failure of a welded fitting shortly after start-up led to extensive field hardness testing on all fittings from this manufacturer.

  13. Vortex flow in the technology of radiation wave cracking (RWC)

    E-Print Network [OSTI]

    L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

    2012-09-16

    This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

  14. Surface Tension regularizes the Crack Singularity of Adhesive Contacts

    E-Print Network [OSTI]

    Stefan Karpitschka; Leen van Wijngaarden; Jacco H. Snoeijer

    2015-08-14

    The elastic and adhesive properties of a solid surface can be quantified by indenting it with a rigid sphere. Indentation tests are classically described by the JKR-law when the solid is very stiff, while recent work highlights the importance of surface tension for exceedingly soft materials. Here we show that surface tension plays a crucial role even for stiff solids: it regularizes the crack-like singularity at the edge of the contact. We find that the edge region exhibits a universal, self-similar structure that emerges from the balance of surface tension and elasticity. The similarity theory provides a complete description for adhesive contacts, reconciling the global adhesion laws and local contact mechanics.

  15. Automated crack control analysis for concrete pavement construction 

    E-Print Network [OSTI]

    Jang, Se Hoon

    2005-11-01

    and the subbase, and concrete shrinkage. Other factors relevant to concrete mixture characteristics such as cement content and type of coarse aggregate affect development of early aged stresses caused by shrinkage and thermally induced contraction. A probabilistic...

  16. Fault-induced delayed voltage recovery in a long inhomogeneous...

    Office of Scientific and Technical Information (OSTI)

    Article: Fault-induced delayed voltage recovery in a long inhomogeneous power-distribution feeder Citation Details In-Document Search This content will become publicly...

  17. Delay-induced driven patterns in coupled Cayley tree networks

    E-Print Network [OSTI]

    Aradhana Singh; Sarika Jalan

    2013-04-04

    We study effects of delay in diffusively coupled logistic maps on the Cayley tree networks. We find that smaller coupling values exhibits sensitiveness for value of delay, and leads to different cluster patterns of self-organized and driven types. Whereas larger coupling strengths are very robust against change in delay values, and leads to stable driven clusters comprising only nodes from last generation of the Calaye tree. Furthermore, introduction of delay exhibits suppression as well as enhancement of synchronization depending upon coupling strength values, hence demonstrating richness of the model. To the end we relate the results with social conflicts and cooperation observed in families.

  18. Characteristic Lyapunov vectors in chaotic time-delayed systems

    E-Print Network [OSTI]

    Diego Pazó; Juan M. López

    2011-01-14

    We compute Lyapunov vectors (LVs) corresponding to the largest Lyapunov exponents in delay-differential equations with large time delay. We find that characteristic LVs, and backward (Gram-Schmidt) LVs, exhibit long-range correlations, identical to those already observed in dissipative extended systems. In addition we give numerical and theoretical support to the hypothesis that the main LV belongs, under a suitable transformation, to the universality class of the Kardar-Parisi-Zhang equation. These facts indicate that in the large delay limit (an important class of) delayed equations behave exactly as dissipative systems with spatiotemporal chaos.

  19. LABORATORY NEW HIRE NOTICE: LABORATORY DELAYED OPENING OR CLOSURE...

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

    LABORATORY NEW HIRE NOTICE: LABORATORY DELAYED OPENING OR CLOSURE DUE TO INCLEAMENT WEATHER During the winter months, the Los Alamos National Laboratory (LANL) may at times...

  20. CRACK GROWTH ANALYSIS OF SOLID OXIDE FUEL CELL ELECTROLYTES

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana

    2003-10-01

    Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis, and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells. Rings cut from the tubes were characterized for microstructure, phase stability, mechanical strength (Weibull modulus) and fracture mechanisms. The strength at operating condition of SOFCs (1000 C) decreased to 95 MPa as compared to room temperature strength of 230 MPa. However, the Weibull modulus remains relatively unchanged. Slow crack growth (SCG) parameter, n = 17 evaluated at room temperature in air was representative of well studied brittle materials. Based on the results, further work was planned to evaluate the strength degradation, modulus and failure in more representative environment of the SOFCs.

  1. Scattering and; Delay, Scale, and Sum Migration

    SciTech Connect (OSTI)

    Lehman, S K

    2011-07-06

    How do we see? What is the mechanism? Consider standing in an open field on a clear sunny day. In the field are a yellow dog and a blue ball. From a wave-based remote sensing point of view the sun is a source of radiation. It is a broadband electromagnetic source which, for the purposes of this introduction, only the visible spectrum is considered (approximately 390 to 750 nanometers or 400 to 769 TeraHertz). The source emits an incident field into the known background environment which, for this example, is free space. The incident field propagates until it strikes an object or target, either the yellow dog or the blue ball. The interaction of the incident field with an object results in a scattered field. The scattered field arises from a mis-match between the background refractive index, considered to be unity, and the scattering object refractive index ('yellow' for the case of the dog, and 'blue' for the ball). This is also known as an impedance mis-match. The scattering objects are referred to as secondary sources of radiation, that radiation being the scattered field which propagates until it is measured by the two receivers known as 'eyes'. The eyes focus the measured scattered field to form images which are processed by the 'wetware' of the brain for detection, identification, and localization. When time series representations of the measured scattered field are available, the image forming focusing process can be mathematically modeled by delayed, scaled, and summed migration. This concept of optical propagation, scattering, and focusing have one-to-one equivalents in the acoustic realm. This document is intended to present the basic concepts of scalar scattering and migration used in wide band wave-based remote sensing and imaging. The terms beamforming and (delayed, scaled, and summed) migration are used interchangeably but are to be distinguished from the narrow band (frequency domain) beamforming to determine the direction of arrival of a signal, and seismic migration in which wide band time series are shifted but not to form images per se. Section 3 presents a mostly graphically-based motivation and summary of delay, scale, and sum beamforming. The model for incident field propagation in free space is derived in Section 4 under specific assumptions. General object scattering is derived in Section 5 and simplified under the Born approximation in Section 6. The model of this section serves as the basis in the derivation of time-domain migration. The Foldy-Lax, full point scatterer scattering, method is derived in Section 7. With the previous forward models in hand, delay, scale, and sum beamforming is derived in Section 8. Finally, proof-of-principle experiments are present in Section 9.

  2. El Nino and the Delayed Action Oscillator

    E-Print Network [OSTI]

    Boutle, I; Römer, R A; Boutle, Ian; Taylor, Richard H. S.; Roemer, Rudolf A.

    2006-01-01

    We study the dynamics of the El Nino phenomenon using the mathematical model of delayed-action oscillator (DAO). Topics such as the influence of the annual cycle, global warming, stochastic influences due to weather conditions and even off-equatorial heat-sinks can all be discussed using only modest analytical and numerical resources. Thus the DAO allows for a pedagogical introduction to the science of El Nino and La Nina while at the same time avoiding the need for large-scale computing resources normally associated with much more sophisticated coupled atmosphere-ocean general circulation models. It is an approach which is ideally suited for student projects both at high school and undergraduate level.

  3. Thermal Regimes of Northeast Streams

    E-Print Network [OSTI]

    Thermal Loading (USGS) Stormwater and Streams ­ Optimizing Stormwater Management to Protect the Thermal

  4. Fatigue cracking of a bare steel first wall in an inertial confinement fusion chamber

    SciTech Connect (OSTI)

    Hunt, R. M.; Abbott, R. P.; Havstad, M. A.; Dunne, A. M.

    2013-06-01

    Inertial confinement fusion power plants will deposit high energy X-rays onto the outer surfaces of the first wall many times a second for the lifetime of the plant. These X-rays create brief temperature spikes in the first few microns of the wall, which cause an associated highly compressive stress response on the surface of the material. The periodicity of this stress pulse is a concern due to the possibility of fatigue cracking of the wall. We have used finite element analyses to simulate the conditions present on the first wall in order to evaluate the driving force of crack propagation on fusion-facing surface cracks. Analysis results indicate that the X-ray induced plastic compressive stress creates a region of residual tension on the surface between pulses. This tension film will likely result in surface cracking upon repeated cycling. Additionally, the compressive pulse may induce plasticity ahead of the crack tip, leaving residual tension in its wake. However, the stress amplitude decreases dramatically for depths greater than 80–100 ?m into the fusion-facing surface. Crack propagation models as well as stress-life estimates agree that even though small cracks may form on the surface of the wall, they are unlikely to propagate further than 100 ?m without assistance from creep or grain erosion phenomena.

  5. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    SciTech Connect (OSTI)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  6. Engineering mesoscale structures with distinct dynamical implications in networks of delay-coupled delay oscillators

    E-Print Network [OSTI]

    Anne-Ly Do; Johannes Höfener; Thilo Gross

    2012-07-05

    The dynamics of networks of interacting systems depends intricately on the interaction topology. When the dynamics is explored, generally the whole topology has to be considered. However, we show that there are certain mesoscale subgraphs that have precise and distinct consequences for the system-level dynamics. In particular, if meso-scale symmetries are present then eigenvectors of the Jacobian localise on the symmetric subgraph and the corresponding eigenvalues become insensitive to the topology outside the subgraph. Hence, dynamical instabilities associated with these eigenvalues can be analyzed without considering the topology outside the subgraph. While such instabilities are thus generated entirely in small network subgraphs, they generally do not remain confined to the subgraph once the instability sets in and thus have system-level consequences. Here we illustrate the analytical investigation of such instabilities in an ecological meta-population model consisting of a network of delay-coupled delay oscillators.

  7. The effect of diluent gases on ignition delay times in the shock tube and in the rapid compression machine

    SciTech Connect (OSTI)

    Wuermel, J.; Silke, E.J.; Curran, H.J.; O Conaire, M.S.; Simmie, J.M.

    2007-10-15

    The diluent gas used in the preparation of test fuel/oxygen mixtures is inert and does not take part in the chemical reaction. However, it does have an effect on the measured ignition delay time both in rapid compression machines and in shock tubes - argon decelerates ignition in the RCM, but accelerates it in the shock tube under some conditions. This opposite effect is due to the times scales involved in these experimental devices. Typical ignition delay times in the RCM are in the region of 1-200 ms, while those in the shock tube are much shorter (10-1000 {mu}s). Comparative RCM experiments and simulations for helium, argon, xenon, and nitrogen have shown extreme heat loss in the postcompression period, particularly for helium. Autoignition measurements of 2,3-dimethylpentane have highlighted a direct dependency of ignition delay time on the type of diluent used, where longer ignition delay time were recorded with argon. This increased ignition delay time is due to the extreme cooling of argon in the postcompression period. This observation was strengthened by comparative experiments with helium and argon, where the diluent effect was even stronger for helium, caused by its higher thermal conductivity. In the shock tube, the diluent effect is opposite to that in the RCM. For dilute mixtures of isooctane, calculations have predicted that mixtures with argon will ignite faster than those with nitrogen, based on the relative heat capacities of the two diluent gases. Overall, we conclude that the choice of diluent gases in experimental devices must be made with care, as ignition delay times can depend strongly on the type of diluent gas used. (author)

  8. Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels

    SciTech Connect (OSTI)

    Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott

    2014-01-09

    Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear fuels are critical to understand the burnup, and thus the fuel efficiency.

  9. Delay Optimal Event Detection on Ad Hoc Wireless Sensor Networks

    E-Print Network [OSTI]

    Kumar, Anurag

    , Bangalore, INDIA email: kprem@ece.iisc.ernet.in, prasanthi.m@gmail.com, anurag@ece.iisc.ernet.in We consider causal order. In this case, the decision statistic depends on the network delays as well, whereas in the network­oblivious case, the decision statistic does not depend on the network delays. This yields

  10. A Structural Result for Delayed Sharing Information Structures

    E-Print Network [OSTI]

    Mahajan, Aditya

    A Structural Result for Delayed Sharing Information Structures Ashutosh Nayyar Department of EECS@eecs.umich.edu Abstract--The n-step delayed sharing information structure is investigated. This information structure is a link between the classical information structure, where information is shared perfectly between

  11. THE INHERENT QUEUING DELAY OF PARALLEL PACKET SWITCHES

    E-Print Network [OSTI]

    Attiya, Hagit

    THE INHERENT QUEUING DELAY OF PARALLEL PACKET SWITCHES (Extended Abstract) Hagit Attiya and David {hagit,hdavid}@cs.technion.ac.il Abstract The parallel packet switch (PPS) is extensively used as the core of con- temporary commercial switches. This paper investigates the inherent queuing delay

  12. The Inherent Queuing Delay of Parallel Packet Switches

    E-Print Network [OSTI]

    Hay, David

    The Inherent Queuing Delay of Parallel Packet Switches Hagit Attiya and David Hay Abstract--The parallel packet switch (PPS) extends the inverse multiplexing architecture and is widely used as the core of contemporary commercial switches. This paper investigates the inherent queuing delay introduced by the PPS

  13. Understanding Network Delay Changes Caused by Routing Events

    E-Print Network [OSTI]

    Mao, Zhuoqing Morley

    such as voice over IP and time-critical financial transactions. This importance is illustrated by past work on understanding the delay constancy of Internet paths and recent work on predicting network delays using virtual- mance metrics of Internet paths. Our work is the first to address this shortcoming by systematically

  14. Delay Constrained Minimum Energy Broadcast in Cooperative Wireless Networks

    E-Print Network [OSTI]

    Krishnamachari, Bhaskar

    Delay Constrained Minimum Energy Broadcast in Cooperative Wireless Networks Marjan Baghaie--We formulate the problem of delay constrained energy-efficient broadcast in cooperative multihop wireless net algorithm that combines dynamic programming and linear programming to yield the min- imum energy broadcast

  15. Perceptual Media Compression for Multiple Viewers with Feedback Delay

    E-Print Network [OSTI]

    Oleg, Komogortsev - Department of Computer Science, Texas State University

    into the impact that such a method can have on transmission bandwidth and computational burden reduction ­ computer conferencing, teleconferencing, and videoconferencing; J.5 [Computers in Other Systems]: Social Perceptual media adaptation, multi-viewer setup. 1. IMPACT OF THE FEEDBACK DELAY Feedback delay is the period

  16. Utility Maximization for Delay Constrained QoS in Wireless

    E-Print Network [OSTI]

    Utility Maximization for Delay Constrained QoS in Wireless I-Hong Hou CSL and Department of CS of utility maxi- mization for clients with delay based QoS requirements in wireless networks. We adopt that the utility of a client is a function of the timely throughput it obtains. We treat the timely throughput

  17. HOPF CALCULATIONS IN DELAYED CAR-FOLLOWING MODELS Gabor Stepan

    E-Print Network [OSTI]

    Awtar, Shorya

    HOPF CALCULATIONS IN DELAYED CAR-FOLLOWING MODELS G´abor St´ep´an and G´abor Orosz Department: A nonlinear car-following model that includes the reaction-time delay of drivers is considered. When, bistability 1. INTRODUCTION There are two important goals of traffic manage- ment when cars follow each other

  18. Optimal Forwarding in Delay Tolerant Networks with Multiple Destinations

    E-Print Network [OSTI]

    Kumar, Anurag

    -Antipolis, 06902 Sophia Antipolis Cedex, France Email: eitan.altman@sophia.inria.fr Abstract--We study the trade-off between delivery delay and energy consumption in a delay tolerant network in which a message (or a file chain and derive the optimal closed loop control (i.e., forwarding policy). However, in practice

  19. An Efficient Method for Random Delay Generation in Embedded Software

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    An Efficient Method for Random Delay Generation in Embedded Software Jean-S´ebastien Coron and Ilya Process Interrupts (rpi) as well as in software by placing "dummy" cy- cles at some points of the program. We give preliminary information on software random delays in Sect. 2. Related work. First detailed

  20. COMPUTATIONAL DELAY IN VEHICLES AND ITS EFFECT ON

    E-Print Network [OSTI]

    Massachusetts at Amherst, University of

    MAY 2012 ABHINNA JAIN B.E., SATHYABAMA UNIVERSITY, INDIA M.S.E.C.E., UNIVERSITY OF MASSACHUSETTS is in the feedback loop of control systems and contributes to feedback delay in addition to already existing delays cause system to underperform in its intended physical behavior and impose a cost in terms of fuel

  1. Water Desalination ReporT Ashdod tender Delayed again

    E-Print Network [OSTI]

    Water Desalination ReporT Israel Ashdod tender Delayed again Last Sunday, Mekorot Development & Enterprise (MD&E) delayed the tender date for the 274,000 m3 /d (72.4 MGD) Ashdod Desalination Project to compete in the international desalination market. Would the technical know-how gleaned from the proposals

  2. Regenerative memory in time-delayed neuromorphic photonic systems

    E-Print Network [OSTI]

    Romeira, B; Figueiredo, José M L; Barland, S; Javaloyes, J

    2015-01-01

    We investigate a regenerative memory based upon a time-delayed neuromorphic photonic oscillator and discuss the link with temporal localized structures. Our experimental implementation is based upon a optoelectronic system composed of a nanoscale nonlinear resonant tunneling diode coupled to a laser that we link to the paradigm of neuronal activity, the FitzHugh-Nagumo model with delayed feedback.

  3. Technique development for field inspection of cracking in seam welded ducts

    SciTech Connect (OSTI)

    Shell, Eric B.; Benson, Craig [Wyle Laboratories, Inc., Dayton, OH 45440 (United States); Liljestrom, Greg C.; Shanahan, Stephen [Wyle Laboratories, Inc., Oklahoma City, OK 73110 (United States)

    2014-02-18

    The resistance seam weld interfaces between alloyed and pure titanium are an in service concern due to precipitation of titanium hydride and resulting embrittlement and cracking. Several inspection techniques were developed and evaluated for field use to characterize the damage in the fleet. Electromagnetic, ultrasonic, florescent penetrant, thermographic, and radiographic techniques were considered. The ultrasonic and electromagnetic approaches were both found suitable. However, the electromagnetic approach is more desirable for field inspections, due to consistency and ease of use. The electromagnetic inspection procedure is able to discriminate between precursor damage and through cracking with sufficient sensitivity to small cracks.

  4. HEATS: Thermal Energy Storage

    SciTech Connect (OSTI)

    2012-01-01

    HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

  5. Car-to-car radio channel measurements at 5 GHz: Pathloss, power-delay profile, and delay-Doppler

    E-Print Network [OSTI]

    Zemen, Thomas

    Car-to-car radio channel measurements at 5 GHz: Pathloss, power-delay profile, and delay Contact: apaier@nt.tuwien.ac.at Abstract-- We carried out a car­to­infrastructure (C2I) and car­to­car (C2­Doppler spectra in a C2C highway scenario, where both cars were traveling in opposite directions. A pathloss

  6. The effect of complex inclusion geometries on fracture and crack coalescence behavior in brittle material

    E-Print Network [OSTI]

    Morgan, Stephen Philip

    2011-01-01

    This research study investigates the cracking processes in a brittle material associated with inclusions of varying shape, orientation and materials. Specifically, this study summarizes a series of uniaxial compression ...

  7. Stress corrosion cracking of steel Stressed-Out Metals: Predicting their Response from the Bottom Up

    E-Print Network [OSTI]

    Simons, Jack

    Stress corrosion cracking of steel Stressed-Out Metals: Predicting their Response from the Bottom;Shocked Iron Ground state bcc undergoes a martensitic phase transformation to hcp at ~13 GPa

  8. Cracked lifting lug welds on ten-ton UF{sub 6} cylinders

    SciTech Connect (OSTI)

    Dorning, R.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Ten-ton, Type 48X, UF{sub 6} cylinders are used at the Portsmouth Gaseous Diffusion Plant to withdraw enriched uranium hexafluoride from the cascade, transfer enriched uranium hexafluoride to customer cylinders, and feed enriched product to the cascade. To accomplish these activities, the cylinders are lifted by cranes and straddle carriers which engage the cylinder lifting lugs. In August of 1988, weld cracks on two lifting lugs were discovered during preparation to lift a cylinder. The cylinder was rejected and tagged out, and an investigating committee formed to determine the cause of cracking and recommend remedial actions. Further investigation revealed the problem may be general to this class of cylinder in this use cycle. This paper discusses the actions taken at the Portsmouth site to deal with the cracked lifting lug weld problem. The actions include inspection activities, interim corrective actions, metallurgical evaluation of cracked welds, weld repairs, and current monitoring/inspection program.

  9. Keep Customers-and Energy-From Slipping Through the Cracks |...

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

    Keep Customers-and Energy-From Slipping Through the Cracks A photo of three people standing and talking to each other, two men and a woman, inside a home. The most successful...

  10. August 27, 2006 CRACKING OF LAMINATES SUBJECTED TO BIAXIAL TENSILE STRAINS

    E-Print Network [OSTI]

    Suo, Zhigang

    ] developed a strain energy release rate expression for the tunnel crack in layers subjected to biaxial tensile stress in the zirconia layer [14] r = r EZr 1- Zr 1+ t w EZr / 1- Zr( ) EAl/ Zr / 1- Al / Zr

  11. Integrating Gas Turbines with Cracking Heaters - Impact on Emissions and Energy Efficiency 

    E-Print Network [OSTI]

    Platvoet, E.

    2011-01-01

    Turbine Exhaust Gas (TEG) contains high levels of oxygen, typically 15 vol. percent, due to gas turbine blade material temperature limits. As such it can be used as an oxidant for combustion in cracking furnaces and reformers. Its high temperature...

  12. Assessment of Initial Test Conditions for Experiments to Assess Irradiation Assisted Stress Corrosion Cracking Mechanisms

    Broader source: Energy.gov [DOE]

    Irradiation-assisted stress corrosion cracking is a key materials degradation issue in today’s nuclear power reactor fleet and affects critical structural components within the reactor core. The...

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

    E-Print Network [OSTI]

    Laubie, Hadrien Hyacinthe

    2013-01-01

    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 ...

  14. Fatigue failure in thin-film polysilicon is due to subcritical cracking within the oxide layer

    E-Print Network [OSTI]

    Alsem, D.H.; Muhlstein, C.L.; Stach, E.A.; Ritchie, R.O.

    2005-01-01

    and manual fracture: no oxide layer thickening (principalCRACKING WITHIN THE OXIDE LAYER D. H. Alsem, a),b),c) E. A.air with thickened oxide layer around the notch root (

  15. Effect of Voids on the Crack Kinking in Single Lap Joints 

    E-Print Network [OSTI]

    Sengab, Ahmed M

    2015-05-12

    Polymer matrix composites are used extensively for their exceptional mechanical properties. The effect of voids on the energy release rate of interface crack has been studied before; however none of the studies investigated ...

  16. Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity

    E-Print Network [OSTI]

    Piccolroaz, Andrea

    2011-01-01

    The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

  17. Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity

    E-Print Network [OSTI]

    Andrea Piccolroaz; Gennady Mishuris

    2012-06-06

    The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

  18. Effect of oxygen potential on high temperature crack growth in alloy 617

    E-Print Network [OSTI]

    Benz, Julian K

    2009-01-01

    The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loading at 650°C. Tests were conducted at a constant stress intensity factor, K, for static loading ...

  19. Electrical Impedance Tomographic Methods for Sensing Strain Fields and Crack Damage in Cementitious Structures

    E-Print Network [OSTI]

    Lynch, Jerome P.

    of their origins (Bungey et al., 2006). After suspicious cracks are encountered, non- destructive (for example, ultrasonic inspection) and partially destructive (for example, core holes) testing can be carried out

  20. On the fracture toughness of ferroelectric ceramics with electric field applied parallel to the crack front

    E-Print Network [OSTI]

    On the fracture toughness of ferroelectric ceramics with electric field applied parallel crack growth. The effects of electric field on the fracture toughness of both initially unpoled and poled materials are investigated. Results for the predicted fracture toughness, remanent strain

  1. Spatial and Temporal Distribution of Desiccation Cracks in Shrink-Swell Soils 

    E-Print Network [OSTI]

    Neely, Haly Lury

    2014-04-17

    Soil crack volume estimates, which are important for hydrology models on shrink-swell soils, are currently based on field measurements of vertical shrinkage and an assumption of isotropic shrinkage; however, few studies have validated the resulting...

  2. A program to design asphalt concrete overlays to mitigate reflection cracking 

    E-Print Network [OSTI]

    Satyanarayana Rao, Sindhu

    2002-01-01

    . Various engineering reinforcing grids have been used in recent years to mitigate the occurrence and propagation of reflection cracking. Reinforcing grids made of fiberglass or polypropylene has been used for this purpose. The main objectives...

  3. Analytical Investigation of Repair Methods for Fatigue Cracks in Steel Bridges

    E-Print Network [OSTI]

    Richardson, Temple

    2012-08-31

    Numerous retrofits have been used to stop distortion-induced fatigue cracks from initiating and propagating in steel bridges. Some decrease stiffness in the web gap region to transfer the load path to an area of higher stiffness, while others...

  4. Webinar: Impacts of Impurities on Hydrogen Assisted Fatigue Crack Growth in Structural Steels

    Broader source: Energy.gov [DOE]

    The Energy Department will present a live webinar titled "Impacts of Impurities on Hydrogen Assisted Fatigue Crack Growth in Structural Steels" on Tuesday, January 12, from 12 to 1 p.m. EST.

  5. Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures 

    E-Print Network [OSTI]

    Izzo, Richard P

    1997-01-01

    The addition of hydrated lime to asphalt has shown to be beneficial with an improvement in the Theological properties of the binder, as well as resistance to permanent deformation (rutting) and fatigue cracking of asphalt concrete mixtures...

  6. Identification of asphalt binder properties that affect cracking performance of hot mixed asphalt concrete pavements 

    E-Print Network [OSTI]

    Hastings, Charles Patrick

    1997-01-01

    with the original mixture designs, compacted in the laboratory, and tested using the National Cooperative Highway Research Program (NCHRP) asphalt aggregate mixture analysis system (AAMAS) test protocols to assess relative resistance to fatigue cracking. Field cores...

  7. Reaction kinetics of olefin saturation in the hydrodesulfurization of fluid catalytic cracked naphtha 

    E-Print Network [OSTI]

    Schumann, Brian Herbert

    1995-01-01

    U.S. governmental agencies are calling for strict environmental regulations on the quality of gasoline. Fluid catalytic cracked naphtha is an important blending component of the gasoline pool. The majority of the sulfur in the gasoline pool comes...

  8. Thermal imaging measurement of lateral diffusivity and non-invasive material defect detection

    DOE Patents [OSTI]

    Sun, Jiangang (Westmont, IL); Deemer, Chris (Downers Grove, IL)

    2003-01-01

    A system and method for determining lateral thermal diffusivity of a material sample using a heat pulse; a sample oriented within an orthogonal coordinate system; an infrared camera; and a computer that has a digital frame grabber, and data acquisition and processing software. The mathematical model used within the data processing software is capable of determining the lateral thermal diffusivity of a sample of finite boundaries. The system and method may also be used as a nondestructive method for detecting and locating cracks within the material sample.

  9. Thermal and Electrical Transport in Oxide Heterostructures

    E-Print Network [OSTI]

    Ravichandran, Jayakanth

    2011-01-01

    of thermal conductivity . . . . . . . . . . . . . . . .4.4 Thermal transport in2.3.2 Thermal transport . . . . . . . . . . . . . . . .

  10. Methodology for extracting local constants from petroleum cracking flows

    DOE Patents [OSTI]

    Chang, Shen-Lin (Woodridge, IL); Lottes, Steven A. (Naperville, IL); Zhou, Chenn Q. (Munster, IN)

    2000-01-01

    A methodology provides for the extraction of local chemical kinetic model constants for use in a reacting flow computational fluid dynamics (CFD) computer code with chemical kinetic computations to optimize the operating conditions or design of the system, including retrofit design improvements to existing systems. The coupled CFD and kinetic computer code are used in combination with data obtained from a matrix of experimental tests to extract the kinetic constants. Local fluid dynamic effects are implicitly included in the extracted local kinetic constants for each particular application system to which the methodology is applied. The extracted local kinetic model constants work well over a fairly broad range of operating conditions for specific and complex reaction sets in specific and complex reactor systems. While disclosed in terms of use in a Fluid Catalytic Cracking (FCC) riser, the inventive methodology has application in virtually any reaction set to extract constants for any particular application and reaction set formulation. The methodology includes the step of: (1) selecting the test data sets for various conditions; (2) establishing the general trend of the parametric effect on the measured product yields; (3) calculating product yields for the selected test conditions using coupled computational fluid dynamics and chemical kinetics; (4) adjusting the local kinetic constants to match calculated product yields with experimental data; and (5) validating the determined set of local kinetic constants by comparing the calculated results with experimental data from additional test runs at different operating conditions.

  11. In situ investigation of high humidity stress corrosion cracking of 7075 aluminum alloy by three-dimensional (3D) X-ray synchrotron tomography

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

    Singh, S. S.; Williams, J. J.; Lin, M. F.; Xiao, X.; De Carlo, F.; Chawla, N.

    2014-05-14

    In situ X-ray synchrotron tomography was used to investigate the stress corrosion cracking behavior of under-aged Al–Zn–Mg–Cu alloy in moisture. The discontinuous surface cracks (crack jumps) mentioned in the literature are actually a single continuous and tortuous crack when observed in three dimension (3D). Contrary to 2D measurements made at the surface which suggest non-uniform crack growth rates, 3D measurements of the crack length led to a much more accurate measurement of crack growth rates.

  12. Tests and analyses for fully plastic fracture mechanics of plane strain mode I crack growth

    SciTech Connect (OSTI)

    McClintock, F.A.; Parks, D.M.; Kim, Y.J.

    1995-12-31

    Under monotonic loading, structures should ideally be ductile enough to provide continued resistance during crack growth. For fully plastic crack growth in low strength alloys, existing asymptotic solutions for elastic-plastic growing cracks are not applicable because they reach the fracture strain only in regions small compared to the inhomogeneities of the actual fracture process. For the limiting case of non-hardening fully-plastic plane strain crack growth, in a number of geometries and loadings the near-tip fields are characterized in terms of three parameters: an effective angle 2{theta}{sub s} between a pair of slip planes, and the normal stress {sigma}{sub s} and the increment of displacement {delta}u{sub s} across the planes. This three-parameter characterization is in contrast to the one- or two-parameter (K or J and T or Q) characterization in linear or non-linear elastic fracture mechanics. These {theta}{sub s}, {sigma}{sub s}, and {delta}u{sub s} parameters are found form the far-field geometries and loadings through slip line fields or least upper bound analyses based on circular arcs. The resulting crack growth, in terms of the crack tip opening angle (CTOA), is a function of {theta}{sub s}, {sigma}{sub s}, and the material. The geometry of the crack growing between two moving slip planes emanating from its tip reduces this function to the critical fracture shear strain left behind the slip planes, {gamma}f, as a function of {sigma}{sub s}. {gamma}f({sigma}{sub s}) is found theoretically from a hole initiation and growth model. It is also found from preliminary fully plastic crack growth experiments on unequally grooved specimens with fixed-grip extension or 4-point bending of a 1018 CF steel.

  13. Thermal Energy Storage

    SciTech Connect (OSTI)

    Rutberg, Michael; Hastbacka, Mildred; Cooperman, Alissa; Bouza, Antonio

    2013-06-05

    The article discusses thermal energy storage technologies. This article addresses benefits of TES at both the building site and the electricity generation source. The energy savings and market potential of thermal energy store are reviewed as well.

  14. Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management

    E-Print Network [OSTI]

    Bouchez, Marc; Visez, Nicolas; Herbinet, Olivier; Fournet, René; Marquaire, Paul-Marie

    2009-01-01

    The last years saw a renewal of interest for hypersonic research in general and regenerative cooling specifically, with a large increase of the number of dedicated facilities and technical studies. In order to quantify the heat transfer in the cooled structures and the composition of the cracked fuel entering the combustor, an accurate model of the thermal decomposition of the fuel is required. This model should be able to predict the fuel chemical composition and physical properties for a broad range of pressures, temperatures and cooling geometries. For this purpose, an experimental and modeling study of the thermal decomposition of generic molecules (long-chain or polycyclic alkanes) that could be good surrogates of real fuels, has been started at the DCPR laboratory located in Nancy (France). This successful effort leads to several versions of a complete kinetic model. These models do not assume any effect from the material that constitutes the cooling channel. A specific experimental study was performed ...

  15. Thermal Management of Solar Cells

    E-Print Network [OSTI]

    Saadah, Mohammed Ahmed

    2013-01-01

    phonon transmission and interface thermal conductance acrossF. Miao, et al. , "Superior Thermal Conductivity of Single-Advanced Materials for Thermal Management of Electronic

  16. Development of a statistically based access delay timeline methodology.

    SciTech Connect (OSTI)

    Rivera, W. Gary; Robinson, David Gerald; Wyss, Gregory Dane; Hendrickson, Stacey M. Langfitt

    2013-02-01

    The charter for adversarial delay is to hinder access to critical resources through the use of physical systems increasing an adversary's task time. The traditional method for characterizing access delay has been a simple model focused on accumulating times required to complete each task with little regard to uncertainty, complexity, or decreased efficiency associated with multiple sequential tasks or stress. The delay associated with any given barrier or path is further discounted to worst-case, and often unrealistic, times based on a high-level adversary, resulting in a highly conservative calculation of total delay. This leads to delay systems that require significant funding and personnel resources in order to defend against the assumed threat, which for many sites and applications becomes cost prohibitive. A new methodology has been developed that considers the uncertainties inherent in the problem to develop a realistic timeline distribution for a given adversary path. This new methodology incorporates advanced Bayesian statistical theory and methodologies, taking into account small sample size, expert judgment, human factors and threat uncertainty. The result is an algorithm that can calculate a probability distribution function of delay times directly related to system risk. Through further analysis, the access delay analyst or end user can use the results in making informed decisions while weighing benefits against risks, ultimately resulting in greater system effectiveness with lower cost.

  17. Delayed feedback control of fractional-order chaotic systems

    E-Print Network [OSTI]

    Aleksandar Gjurchinovski; Trifce Sandev; Viktor Urumov

    2011-07-06

    We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the parameter ranges for successful stabilization of unstable equilibria in the plane parametrizad by the feedback gain and the time delay. An insight into the control mechanism is gained by analyzing the characteristic equation of the controlled system, showing that the control scheme fails to control unstable equilibria having an odd number of positive real eigenvalues. We demonstrate that the method can also stabilize unstable periodic orbits for a suitable choice of the feedback gain, providing that the time delay is chosen to coincide with the period of the target orbit. In addition, it is shown numerically that delayed feedback control with a sinusoidally modulated time delay significantly enlarges the stability region of the steady states in comparison to the classical time-delayed feedback scheme with a constant delay.

  18. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    time-varying solar energy inputs and thermal or powerthermal energy becomes apparent with the development of solar

  19. Crack initiation in smooth fatigue specimens of austenitic stainless steel in light water reactor environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Smith, J. L.

    1999-04-08

    The fatigue design curves for structural materials specified in Section III of the ASME Boiler and Pressure Vessel Code are based on tests of smooth polished specimens at room temperature in air. The effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves; however, recent test data illustrate the detrimental effects of LWR coolant environments on the fatigue resistance of austenitic stainless steels (SSs). Certain loading and environmental conditions have led to test specimen fatigue lives that are significantly shorter than those obtained in air. Results of fatigue tests that examine the influence of reactor environments on crack initiation and crack growth of austenitic SSs are presented. Block loading was used to mark the fracture surface to determine crack length as a function of fatigue cycles in water environments, Crack lengths were measured by scanning electron microscopy. The mechanism for decreased fatigue life in LWR environments is discussed, and crack growth rates in the smooth fatigue specimens are compared with existing data from studies of crack growth rates.

  20. Stress-corrosion fatigue-crack growth in a Zr-based bulk amorphousmetal

    SciTech Connect (OSTI)

    Schroeder, V.; Ritchie, R.O.

    2005-09-21

    Electrochemical and mechanical experiments were conducted to analyze the environmentally-influenced cracking behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5. This study was motivated by a scientific interest in mechanisms of fatigue-crack propagation in an amorphous metal, and by a practical interest in the use of this amorphous metal in applications that take advantage of its unique properties, including high specific strength, large elastic strains and low damping. The objective of the work was to determine the rate and mechanisms of subcritical crack growth in this metallic glass in an aggressive environment. Specifically, fatigue-crack propagation behavior was investigated at a range of stress intensities in air and aqueous salt solutions by examining the effects of loading cycle, stress-intensity range, solution concentration, anion identity, solution de-aeration, and bulk electrochemical potential. Results indicate that crack growth in aqueous solution in this alloy is driven by a stress-assisted anodic reaction at the crack tip. Rate-determining steps for such behavior are reasoned to be electrochemical, stress-dependent reaction at near-threshold levels, and mass transport at higher (steady-state) growth rates.

  1. Sonic IR crack detection of aircraft turbine engine blades with multi-frequency ultrasound excitations

    SciTech Connect (OSTI)

    Zhang, Ding; Han, Xiaoyan; Newaz, Golam

    2014-02-18

    Effectively and accurately detecting cracks or defects in critical engine components, such as turbine engine blades, is very important for aircraft safety. Sonic Infrared (IR) Imaging is such a technology with great potential for these applications. This technology combines ultrasound excitation and IR imaging to identify cracks and flaws in targets. In general, failure of engine components, such as blades, begins with tiny cracks. Since the attenuation of the ultrasound wave propagation in turbine engine blades is small, the efficiency of crack detection in turbine engine blades can be quite high. The authors at Wayne State University have been developing the technology as a reliable tool for the future field use in aircraft engines and engine parts. One part of the development is to use finite element modeling to assist our understanding of effects of different parameters on crack heating while experimentally hard to achieve. The development has been focused with single frequency ultrasound excitation and some results have been presented in a previous conference. We are currently working on multi-frequency excitation models. The study will provide results and insights of the efficiency of different frequency excitation sources to foster the development of the technology for crack detection in aircraft engine components.

  2. Adaptive control of time delay systems and applications to automotive control problems

    E-Print Network [OSTI]

    Yildiz, Yildiray

    2009-01-01

    This thesis is about the adaptive control of time delay systems with applications to automotive control problems. The stabilization of systems involving time delays is a difficult problem since the existence of a delay may ...

  3. Multiwavelength Thermal Emission

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Multiwavelength Astronomy NASA #12;Thermal Emission #12;Thermal Emission Non-thermal p-p collisions Optical IR Radio/ Microwave sources of emission massive stars, WHIM, Ly many dust, cool objects-ray ~GeV Gamma-ray ~TeV sources of emission AGN, clusters, SNR, binaries, stars AGN (obscured), shocks

  4. Thermal neutron detection system

    DOE Patents [OSTI]

    Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

    2000-01-01

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  5. Thermal Performance Benchmarking (Presentation)

    SciTech Connect (OSTI)

    Moreno, G.

    2014-11-01

    This project will benchmark the thermal characteristics of automotive power electronics and electric motor thermal management systems. Recent vehicle systems will be benchmarked to establish baseline metrics, evaluate advantages and disadvantages of different thermal management systems, and identify areas of improvement to advance the state-of-the-art.

  6. Synchronization of networks of oscillators with distributed delay coupling

    E-Print Network [OSTI]

    Y. N. Kyrychko; K. B. Blyuss; E. Schoell

    2014-10-27

    This paper studies the stability of synchronized states in networks where couplings between nodes are characterized by some distributed time delay, and develops a generalized master stability function approach. Using a generic example of Stuart-Landau oscillators, it is shown how the stability of synchronized solutions in networks with distributed delay coupling can be determined through a semi-analytic computation of Floquet exponents. The analysis of stability of fully synchronized and of cluster or splay states is illustrated for several practically important choices of delay distributions and network topologies.

  7. Design of coupling for synchronization in time-delayed systems

    E-Print Network [OSTI]

    Dibakar Ghosh; Ioan Grosu; Syamal Kumar Dana

    2012-07-03

    We report a design of delay coupling for targeting desired synchronization in delay dynamical systems. We target synchronization, antisynchronization, lag-, antilag- synchronization, amplitude death (or oscillation death) and generalized synchronization in mismatched oscillators. A scaling of the size of an attractor is made possible in different synchronization regimes. We realize a type of mixed synchronization where synchronization, antisynchronization coexist in different pairs of state variables of the coupled system. We establish the stability condition of synchronization using the Krasovskii-Lyapunov function theory and the Hurwitz matrix criterion. We present numerical examples using the Mackey-Glass system and a delay R\\"{o}ssler system.

  8. Electronic Implementation of the Mackey-Glass Delayed Model

    E-Print Network [OSTI]

    Pablo Amil; Cecilia Cabeza; Arturo C. Martí

    2014-08-21

    The celebrated Mackey-Glass model describes the dynamics of physiological \\textit{delayed} systems in which the actual evolution depends on the values of the variables at some \\textit{previous} times. This kind of systems are usually expressed by delayed differential equations which turn out to be infinite-dimensional. In this contribution, an electronic implementation mimicking the Mackey-Glass model is proposed. New approaches for both the nonlinear function and the delay block are made. Explicit equations for the actual evolution of the implementation are derived. Simulations of the original equation, the circuit equation, and experimental data show great concordance.

  9. Syneresis and delayed detachment in agar plates

    E-Print Network [OSTI]

    Thibaut Divoux; Bosi Mao; Patrick Snabre

    2015-02-20

    Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amount of solvent. These gels undergo spontaneous aging, called syneresis that consists in the shrinkage of the gel matrix and the progressive expulsion of the solvent. As a result, a biogel originally casted in a container often lose contact with the container sidewalls, and the detachment time is a priori difficult to anticipate since it may occur over variable time spans (from hours to days). Here we report on the syneresis phenomena in agar plates that consist in Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analysis allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time $t^*$ is surprisingly not controlled by the mass loss as one would intuitively expect. Instead, $t^*$ is strongly correlated to the gel minimum thickness $e_{min}$ measured along the sidewall of the plate, and increases as a robust function of $e_{min}$ independently of the prior mass-loss history. Time-resolved correlation spectroscopy atypically applied to such weakly diffusive media gives access to the local thinning rate of the gel. This technique also allows us to detect the gel micro-displacements that are triggered by the water evaporation prior to the detachment, and even to anticipate the latter from a few hours. Our work provides observables to predict the detachment time of agar gels in dishes, and highlights the relevance of speckle pattern correlation analysis for the quantitative investigation of the syneresis dynamics in biopolymer gels.

  10. Dynamic Thermal Management in 3D Multicore Architectures Ayse K. Coskun

    E-Print Network [OSTI]

    Simunic, Tajana

    approach to overcome the power consumption and delay problems associated with the interconnects by reducing due to the high power density resulting from placing computational units on top of each other. In this work, we first investigate how the existing thermal management, power management and job scheduling

  11. 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

    2013-04-15

    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.

  12. Inuence of foreign-object damage on crack initiation and early crack growth during high-cycle fatigue of Ti6Al4V

    E-Print Network [OSTI]

    Ritchie, Robert

    ; Ti±6Al±4V 1. Introduction The high-cycle fatigue (HCF) of aircraft gas-turbine engine components has-cycle fatigue of Ti±6Al±4V J.O. Peters, R.O. Ritchie * Department of Materials Science and Mineral Engineering of small surface fatigue cracks in a Ti±6Al±4V alloy, processed for typical turbine blade applications

  13. Chaos anti-synchronization in multiple time delay power systems

    E-Print Network [OSTI]

    Elman Shahverdiev

    2015-09-20

    We elucidate conditions for chaos anti-synchronization between two uni-directionally coupled multiple time delay power systems. The results are of some importance to prevent power black-out in the entire power grid.

  14. Time delay for dispersive systems in quantum scattering theory

    E-Print Network [OSTI]

    Rafael Tiedra de Aldecoa

    2008-10-06

    We consider time delay and symmetrised time delay (defined in terms of sojourn times) for quantum scattering pairs $\\{H_0=h(P),H\\}$, where $h(P)$ a dispersive operator of hypoelliptic-type. For instance $h(P)$ can be one of the usual elliptic operators such as the Schr\\"odinger operator $h(P)=P^2$ or the square-root Klein-Gordon operator $h(P)=\\sqrt{1+P^2}$. We show under general conditions that the symmetrised time delay exists for all smooth even localization functions. It is equal to the Eisenbud-Wigner time delay plus a contribution due to the non-radial component of the localization function. If the scattering operator $S$ commutes with some function of the velocity operator $\

  15. A structural approach to delay optimization in combinational circuits 

    E-Print Network [OSTI]

    Munshi, Avinash

    1999-01-01

    A major problem in circuit design is achieving the maximum performance for a given technology. In the context of logic synthesis and optimization, maximizing performance means reducing the maximum propagation delay from circuit inputs to outputs...

  16. Delay-sensitive communication over wireless multihop channels 

    E-Print Network [OSTI]

    Ali, Omar Ahmed

    2009-05-15

    Wireless systems of today face the dual challenge of both supporting large traffic flows and providing reliable quality of service to different delay-sensitive applications. For such applications, it is essential to derive meaningful performance...

  17. On delay-sensitive communication over wireless systems 

    E-Print Network [OSTI]

    Liu, Lingjia

    2009-05-15

    This dissertation addresses some of the most important issues in delay-sensitive communication over wireless systems and networks. Traditionally, the design of communication networks adopts a layered framework where each layer serves as a “black box...

  18. Inter-sensor propagation delay estimation using sources of opportunity

    E-Print Network [OSTI]

    Vincent, Rémy; Michel, Olivier; Lacoume, Jean-Louis

    2015-01-01

    Propagation delays are intensively used for Structural Health Monitoring or Sensor Network Localization. In this paper, we study the performances of acoustic propagation delay estimation between two sensors, using sources of opportunity only. Such sources are defined as being uncontrolled by the user (activation time, location, spectral content in time and space), thus preventing the direct estimation with classical active approaches, such as TDOA, RSSI and AOA. Observation models are extended from the literature to account for the spectral characteristics of the sources in this passive context and we show how time-filtered sources of opportunity impact the retrieval of the propagation delay between two sensors. A geometrical analogy is then proposed that leads to a lower bound on the variance of the propagation delay estimation that accounts for both the temporal and the spatial properties of the sources field.

  19. Complete chaotic synchronization in mutually coupled time-delay systems

    E-Print Network [OSTI]

    Alexandra S. Landsman; Ira B. Schwartz

    2007-10-25

    Complete chaotic synchronization of end lasers has been observed in a line of mutually coupled, time-delayed system of three lasers, with no direct communication between the end lasers. The present paper uses ideas from generalized synchronization to explain the complete synchronization in the presence of long coupling delays, applied to a model of mutually coupled semiconductor lasers in a line. These ideas significantly simplify the analysis by casting the stability in terms of the local dynamics of each laser. The variational equations near the synchronization manifold are analyzed, and used to derive the synchronization condition that is a function of the parameters. The results explain and predict the dependence of synchronization on various parameters, such as time-delays, strength of coupling and dissipation. The ideas can be applied to understand complete synchronization in other chaotic systems with coupling delays and no direct communication between synchronized sub-systems.

  20. Opportunities for Process Monitoring Techniques at Delayed Access Facilities

    SciTech Connect (OSTI)

    Curtis, Michael M.; Gitau, Ernest TN; Johnson, Shirley J.; Schanfein, Mark; Toomey, Christopher

    2013-09-20

    Except for specific cases where the International Atomic Energy Agency (IAEA) maintains a continuous presence at a facility (such as the Japanese Rokkasho Reprocessing Plant), there is always a period of time or delay between the moment a State is notified or aware of an upcoming inspection, and the time the inspector actually enters the material balance area or facility. Termed by the authors as “delayed access,” this period of time between inspection notice and inspector entrance to a facility poses a concern. Delayed access also has the potential to reduce the effectiveness of measures applied as part of the Safeguards Approach for a facility (such as short-notice inspections). This report investigates the feasibility of using process monitoring to address safeguards challenges posed by delayed access at a subset of facility types.

  1. Effect of resolved branches on the performance of delayed branching 

    E-Print Network [OSTI]

    Ramabhadran, Anurekha

    1995-01-01

    The impact of resolved branch instructions on the performance of the delayed branching scheme is studied for a two-instruction-issue superscalar pipelined RISC processor. Two processor models are created in Verilog HDL, ...

  2. Time-delayed directional beam phased array antenna

    DOE Patents [OSTI]

    Fund, Douglas Eugene; Cable, John William; Cecil, Tony Myron

    2004-10-19

    An antenna comprising a phased array of quadrifilar helix or other multifilar antenna elements and a time-delaying feed network adapted to feed the elements. The feed network can employ a plurality of coaxial cables that physically bridge a microstrip feed circuitry to feed power signals to the elements. The cables provide an incremental time delay which is related to their physical lengths, such that replacing cables having a first set of lengths with cables having a second set of lengths functions to change the time delay and shift or steer the antenna's main beam. Alternatively, the coaxial cables may be replaced with a programmable signal processor unit adapted to introduce the time delay using signal processing techniques applied to the power signals.

  3. Proportional Differentiated Services: Delay Differentiation and Packet Scheduling

    E-Print Network [OSTI]

    Dovrolis, Constantinos

    Proportional Differentiated Services: Delay Differentiation and Packet Scheduling Constantinos propose the proportional differ­ entiation model as a way to refine and quantify this basic premise of relative differentiated services. The proportional differentiation model aims to provide the network

  4. Delayed neutron energy spectrum measurements of actinide waste isotopes 

    E-Print Network [OSTI]

    Comfort, Christopher M.

    1998-01-01

    was irradiated using the Texas A&M Nuclear Science Center Reactor (NSCR). Three proton recoil detectors, operating individually, in conjunction with MCNP calculated response functions, were used to measure the delayed neutron energy spectra of each isotope...

  5. Generalization of neuron network model with delay feedback

    E-Print Network [OSTI]

    Sanjeet Maisnam; R. K. Brojen Singh

    2015-07-16

    We present generalized delayed neural network (DNN) model with positive delay feedback and neuron history. The local stability analysis around trivial local equilibria of delayed neural networks has applied and determine the conditions for the existence of zero root. We develop few innovative delayed neural network models in different dimensions through transformation and extension of some existing models. We found that zero root can have multiplicity two under certain conditions. We further show how the characteristic equation can have zero root and its multiplicity is dependent on the conditions undertaken. Finally, we generalize the neural network of $N$ neurons through which we determine the general form of Jacobian of the linear form and corresponding characteristic equation of the system.

  6. Department of Energy and USEC Announce Decision to Delay USEC...

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

    to delay a final review on the company's loan guarantee application for the American Centrifuge Plant in Piketon, OH. The Department plans to defer review of the application until...

  7. Time delay for an abstract quantum scattering process

    E-Print Network [OSTI]

    S. Richard

    2011-03-20

    In this short review paper, we discuss the concept of time delay for an abstract quantum scattering system. Its definition in terms of sojourn times is explained as well as its identity with the so-called Eisenbud-Wigner time delay. Necessary and natural conditions for such a construction are introduced and thoroughly discussed. Assumptions and statements are precisely formulated but proofs are contained in two companion papers written in collaboration with R. Tiedra de Aldecoa.

  8. Cracking of n-butane catalyzed by iron- and maganese-promoted sulfated zirconia

    SciTech Connect (OSTI)

    Cheung, T.K.; d`Itri, J.L.; Gates, B.C.

    1995-05-01

    Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, the significant reactions were isomerization and disproportionation; in the range of 225-300{degrees}C, these reactions were accompanied by cracking, and at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part from coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup {minus}9}mol/(g of catalyst {center_dot}s). This comparison suggests that the catalytic activity of the promoted sulfated zirconia at 450{degrees}C is about the same as that of the zeolite, although its activity for n-butane isomerization and disproportionation at temperatures <100{degrees}C is orders of magnitude greater than those of zeolites. Thus the indication of superacidity of the promoted sulfated zirconia does not extend to high temperatures. The results raise questions about the nature of the presumed superacidity: perhaps the low-temperature reactions may involve catalyst functions other than the acidic function responsible for high-temperature cracking reactions or perhaps superacidic sites may be very rapidly poisoned at cracking temperatures. 14 refs., 8 figs., 3 tabs.

  9. Delayed-fission properties of neutron-deficient americium nuclei

    SciTech Connect (OSTI)

    Hall, H.L. (California Univ., Berkeley, CA (USA). Dept. of Chemistry)

    1989-10-23

    Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.

  10. The effect of residuals on the presence of intergranular surface cracks on continuously cast billets

    SciTech Connect (OSTI)

    Wijngaarden, M.J.U.T. van; Visagie, G.P.

    1996-12-31

    During 1991, Iscor Vereeniging experienced a dramatic increase in the rejection rate of specialty steel bars rolled from continuously cast billets due to the presence of seams on the bars. The seams originated from tearing of the billets during the first 2 passes in the roughing mill during hot rolling. The defective billets were found to contain fine intergranular cracks on the surface. Such cracks have been described in the literature and have been attributed to the presence of high levels of residuals resulting in the well-known phenomenon of surface hot shortness which results from the enrichment of residuals at the grain boundaries after preferential oxidation of iron during scaling of the steel. The present investigation revealed that the effect of residuals on intergranular surface cracking is a complex interaction between steel composition and casting conditions such as casting speed, intensity of secondary cooling, section size, and mold type. This paper quantifies the effect of residuals on the intergranular surface cracking of continuously cast billets and quantitatively relates the incidence of these cracks to parameters which can be controlled during steelmaking and continuous casting.

  11. Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz

    SciTech Connect (OSTI)

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang

    2008-03-15

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

  12. Detection of submicron scale cracks and other surface anomalies using positron emission tomography

    DOE Patents [OSTI]

    Cowan, Thomas E.; Howell, Richard H.; Colmenares, Carlos A.

    2004-02-17

    Detection of submicron scale cracks and other mechanical and chemical surface anomalies using PET. This surface technique has sufficient sensitivity to detect single voids or pits of sub-millimeter size and single cracks or fissures of millimeter size; and single cracks or fissures of millimeter-scale length, micrometer-scale depth, and nanometer-scale length, micrometer-scale depth, and nanometer-scale width. This technique can also be applied to detect surface regions of differing chemical reactivity. It may be utilized in a scanning or survey mode to simultaneously detect such mechanical or chemical features over large interior or exterior surface areas of parts as large as about 50 cm in diameter. The technique involves exposing a surface to short-lived radioactive gas for a time period, removing the excess gas to leave a partial monolayer, determining the location and shape of the cracks, voids, porous regions, etc., and calculating the width, depth, and length thereof. Detection of 0.01 mm deep cracks using a 3 mm detector resolution has been accomplished using this technique.

  13. Fracture toughness results and preliminary analysis for International Cooperative Test Program on specimens containing surface cracks

    SciTech Connect (OSTI)

    Reuter, W.G.; Elfer, N.C.; Hull, D.A.; Newman, J.C. Jr.; Munz, D.; Panontin, T.L.

    1997-12-31

    Specimens containing surface cracks were tested in either tension or bending to compare the stress intensity factor at failure with plane strain fracture toughness (K{sub Ic}) in an International Cooperative Test Program. The material was heat treated to {sigma}{sub ys} = 1 587 MPa and K{sub Ic} = 54 MPa m{sub 1/2}. Because substantial stable crack growth occurred for some specimens, the test plan was modified to include detecting the onset of crack growth. It is shown that P{sub max} and the original fatigue precrack size cannot be employed to calculate K{sub max} for comparison with K{sub Ic} when significant stable crack growth occurs. However, using P{sub init} (load at which stable crack growth is initiated) and the original fatigue precrack size to calculate K{sub max} or K{sub {phi}=30{degree}} provides a very useful comparison with K{sub Ic}. The influence of variations in fatigue precrack configuration on test results are also discussed.

  14. Acoustic Emission and Guided Wave Monitoring of Fatigue Crack Growth on a Full Pipe Specimen

    SciTech Connect (OSTI)

    Meyer, Ryan M.; Cumblidge, Stephen E.; Ramuhalli, Pradeep; Watson, Bruce E.; Doctor, Steven R.; Bond, Leonard J.

    2011-05-06

    Continuous on-line monitoring of active and passive systems, structures and components in nuclear power plants will be critical to extending the lifetimes of nuclear power plants in the US beyond 60 years. Acoustic emission and guided ultrasonic waves are two tools for continuously monitoring passive systems, structures and components within nuclear power plants and are the focus of this study. These tools are used to monitor fatigue damage induced in a SA 312 TP304 stainless steel pipe specimen. The results of acoustic emission monitoring indicate that crack propagation signals were not directly detected. However, acoustic emission monitoring exposed crack formation prior to visual confirmation through the detection of signals caused by crack closure friction. The results of guided ultrasonic wave monitoring indicate that this technology is sensitive to the presence and size of cracks. The sensitivity and complexity of GUW signals is observed to vary with respect to signal frequency and path traveled by the guided ultrasonic wave relative to the crack orientation.

  15. Fracture behavior of ceramic laminates in bending-I. Modeling of crack propagation

    SciTech Connect (OSTI)

    Phillipps, A.J.; Clegg, W.J.; Clyne, T.W. . Dept. of Materials Science and Metallurgy)

    1993-03-01

    This paper concerns the fracture behavior of specimens made up of ceramic sheets, separated by thin interlayers, which act to deflect cracks and thus to prevent catastrophic failure of the specimen. The treatment is divided into two parts. In this paper, the behavior of this type of material during bending is quantitatively modeled. The model is based on through-thickness cracks propagating when a critical stress is reached and interfacial cracks then advancing a distance dictated by the available energy. The variation in laminae strengths is modeled using a Monte Carlo method to determine the strength of successive laminae for a given Weibull modulus. The model is used to predict load/displacement plots and to explore the effects of changes in loading geometry and specimen variables, including Young's modulus, lamina strength, loading span, interfacial toughness, as well as lamina and sample thickness. A distinction is drawn between the energy actually absorbed in causing complete failure of the specimen as measured from the area under the load/displacement curve, and the amount of energy necessary to cause the crack propagation which occurred. These differ if the energy available to drive the interfacial cracks is more than sufficient for them to reach the ends of the specimen or if energy is dissipated elsewhere in the system. A criterion is derived by which specimens can be designed so as to minimize the difference between these two quantities. The significance of this concept in optimizing the toughness of these laminated materials is briefly discussed.

  16. Catalytic thermal barrier coatings

    DOE Patents [OSTI]

    Kulkarni, Anand A. (Orlando, FL); Campbell, Christian X. (Orlando, FL); Subramanian, Ramesh (Oviedo, FL)

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  17. Characterization of geothermal reservoir crack patterns using shear-wave

    Open Energy Info (EERE)

    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 Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoopButte County,Camilla,Thermal Gradient HolesCentral,Chandler HillsOpensplitting |

  18. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01

    aquifers for thermal energy storage. Problems outlined abovean Aquifer Used for Hot Water Storage: Digital Simulation ofof Aquifer Systems for Cyclic Storage of Water," of the Fall

  19. Scattering Solar Thermal Concentrators

    Office of Environmental Management (EM)

    sunshot DOEGO-102012-3669 * September 2012 MOTIVATION All thermal concentrating solar power (CSP) systems use solar tracking, which involves moving large mirror surfaces...

  20. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    pp. 67-73, 2003. [17] "Energy Requirements of Desalinationof solar collectors and thermal energy storage in solarapplications," Applied Energy, pp. 538-553, 2013. [20] P. G.

  1. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01

    C. Y. Zhao, "A review of solar collectors and thermal energya Passive Flat-Plate Solar Collector," International Journalof Flat Plate Solar Collector Equipped with Rectangular Cell

  2. Assessing the Costs Attributed to Project Delay Curtis Beaty, P.E.

    E-Print Network [OSTI]

    and Commercial Value of Time Change in Highway Cost Index Total Month of Delay Estimated Return on Investment Cost Index (HCI) (during Delay) 11% 29% 3% Travel-Related Variables Length of Project 2.7 2.6 1 Impacts 8.0% 8.0% 8.0% Examples of Cost of Construction Delay #12;Monthly Cost of Project Delay Small

  3. Study of the beta delayed particle emission from 48Mn and its relevance for explosive nucleosynthesis

    E-Print Network [OSTI]

    Martel, I

    2015-01-01

    Study of the beta delayed particle emission from 48Mn and its relevance for explosive nucleosynthesis

  4. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Final report

    SciTech Connect (OSTI)

    Wallace, J.F.; Wang, Y.; Schwam, D.

    1997-06-01

    The objective of this study was to improve average die life by optimizing die steel composition and the die processing. Four different steels, K,Q,C and Premium Grade H-13 have been investigated for thermal fatigue resistance and toughness. Optimum heat treatment processing has been determined for each steel with respect to austenitizing temperature and tempering conditions. The effect of the quenching rate on the thermal fatigue resistance and toughness of the die steels and the effect of Electro-Discharge Machining (EDM) on the thermal fatigue resistance were also determined. The immersion thermal fatigue specimen developed at CWRU was used to determine the thermal fatigue resistance as characterized by the two parameters of average maximum crack length and total crack area. The Charpy V-notch impact test was used over a -100{degrees}F to 450{degrees}F testing temperature range to evaluate the toughness and the brittle-ductile transition behavior. K steel has been identified as superior in performance compared to Premium Grade H-13. Q and C provide lower toughness and thermal fatigue resistance than H-13. Faster cooling rates provide higher thermal fatigue resistance and toughness. Higher austenitizing temperatures such as 1925{degrees}F compared to 1875{degrees}F provide better thermal fatigue resistance, but lower austenitizing temperatures of 1875{degrees}F provide better toughness. Higher hardness improves thermal fatigue resistance, but reduces toughness. A minimum of Rc 46 hardness is desired for aluminum die casting dies. EDM reduces the thermal fatigue resistance compared to conventional machining operations. When the EDM process of multiple small steps of decreasing energy and post-EDM treatments are employed, the effect can be reduced to a very slight amount. Preliminary evidence of the superior performance of the K steel has been provided by ongoing field testing of inserts in multiple cavity dies.

  5. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, P.C.

    1997-05-06

    A method is described for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap there between. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition. 6 figs.

  6. Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks

    SciTech Connect (OSTI)

    Dugan, Sandra; Wagner, Sabine [Materials Testing Institute University of Stuttgart (MPA), Pfaffenwaldring 32, 70569 Stuttgart (Germany)

    2014-02-18

    Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

  7. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, Peter C. (Idaho Falls, ID)

    1997-01-01

    A method for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap therebetween. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition.

  8. Can surface cracks and unipolar arcs explain breakdown and gradient limits?

    SciTech Connect (OSTI)

    Insepov, Zeke; Norem, Jim

    2013-01-15

    The authors argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown and vacuum arc data. They outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar arcs and cracks can simplify the picture of breakdown and gradient limits in accelerators, tokamaks as well as laser ablation, micrometeorites, and other applications. Cracks are commonly seen in SEM images of arc damage and they are produced as the liquid metal cools. They can produce the required field enhancements to explain field emission data and can produce mechanical failure of the surface that would trigger breakdown events. Unipolar arcs can produce currents sufficient to short out rf structures, and can cause the sort of damage seen in SEM images. They should be unstable, and possibly self-quenching, as seen in optical fluctuations and surface damage. The authors describe some details and consider the predictions of this simple model.

  9. Method and apparatus for detecting external cracks from within a metal tube

    DOE Patents [OSTI]

    Caffey, Thurlow W. H. (Albuquerque, NM)

    2001-08-07

    A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.

  10. Fast Thermal Simulation for Architecture Level Dynamic Thermal Management

    E-Print Network [OSTI]

    Tan, Sheldon X.-D.

    Fast Thermal Simulation for Architecture Level Dynamic Thermal Management Pu Liu, Zhenyu Qi, Hang temperature by dynamic thermal managements becomes necessary. This paper proposes a novel approach to the thermal analysis at chip architecture level for efficient dynamic thermal management. Our new approach

  11. Mechanisms for fracture and fatigue-crack propagation in a bulk metallic glass

    SciTech Connect (OSTI)

    Gilbert, C.J.; Schroeder, V.; Ritchie, R.O. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1999-07-01

    The fracture and fatigue properties of a newly developed bulk metallic glass alloy, Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (at. pct), have been examined. Experimental measurements using conventional fatigue precracked compact-tension C(T) specimens ({approximately}7-mm thick) indicated that the fully amorphous alloy has a plane-strain fracture toughness comparable to polycrystalline aluminum alloys. However, significant variability was observed and possible sources are identified. The fracture surfaces exhibited a vein morphology typical of metallic glasses, and, in some cases, evidence for local melting was observed. Attempts were made to rationalize the fracture toughness in terms of a previously developed micromechanical model based on the Taylor instability, as well as on the observation of extensive crack branching and deflection. Upon partial or complete crystallization, however, the alloy was severely embrittled, with toughnesses dropping to {approximately}1 MPa {radical}m. Commensurate with this drop in toughness was a marginal increase in hardness and a reduction in ductility (as measured via depth-sensing indentation experiments). Under cyclic loading, crack-propagation behavior in the amorphous structure was similar to that observed in polycrystalline steel and aluminum alloys. Moreover, the crack-advance mechanism was associated with alternating blunting and resharpening of the crack tip. This was evidenced by striations on fatigue fracture surfaces. Conversely, the (unnotched) stress/life (S/N) properties were markedly different. Crack initiation and subsequent growth occurred quite readily, due to the lack of microstructural barriers that would normally provide local crack-arrest points. This resulted in a low fatigue limit of {approximately}4 pct of ultimate tensile strength.

  12. EDDY CURRENT SYSTEM FOR DETECTION OF CRACKING BENEATH BRAIDING IN CORRUGATED METAL HOSE

    SciTech Connect (OSTI)

    Wincheski, Buzz [NASA Langley Research Center, Hampton, VA 23681 (United States); Simpson, John [Lockheed Martin Space Operations, Hampton, VA 23681 (United States); Hall, George [George Washington University, Washington, D.C. 20052 (United States)

    2009-03-03

    In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.

  13. A tool to detect external cracks from within a metal tube

    SciTech Connect (OSTI)

    Caffey, T.W.H.

    1997-01-01

    A tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is outlined for the detection of external sidewall cracks in boiler tubes. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to 40dB in thin-walled boiler tubes.

  14. Thermal protection apparatus

    DOE Patents [OSTI]

    Bennett, G.A.; Elder, M.G.; Kemme, J.E.

    1984-03-20

    The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

  15. Thermal protection apparatus

    DOE Patents [OSTI]

    Bennett, Gloria A. (Los Alamos, NM); Elder, Michael G. (Los Alamos, NM); Kemme, Joseph E. (Albuquerque, NM)

    1985-01-01

    An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

  16. Thermal radiation Ron Zevenhoven

    E-Print Network [OSTI]

    Zevenhoven, Ron

    .00032, similarly for 2·T = 0.7·2500 = 1750 µmK4 this gives f0-2 = 0.03392. Thus for 0.4 - 0.7 µm, f1-2 = 0Thermal radiation revisited Ron Zevenhoven Åbo Akademi University Thermal and Flow Engineering Laboratory / Värme- och strömningsteknik tel. 3223 ; ron.zevenhoven@abo.fi Process Engineering

  17. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    LASP's mechanical analysts also lead mechanical verification testing including: random vibration, forceMechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has, and ground- based mechanical systems. Instrument Design Building on decades of design experience that has

  18. Thermal treatment wall

    DOE Patents [OSTI]

    Aines, Roger D. (Livermore, CA); Newmark, Robin L. (Livermore, CA); Knauss, Kevin G. (Livermore, CA)

    2000-01-01

    A thermal treatment wall emplaced to perform in-situ destruction of contaminants in groundwater. Thermal destruction of specific contaminants occurs by hydrous pyrolysis/oxidation at temperatures achievable by existing thermal remediation techniques (electrical heating or steam injection) in the presence of oxygen or soil mineral oxidants, such as MnO.sub.2. The thermal treatment wall can be installed in a variety of configurations depending on the specific objectives, and can be used for groundwater cleanup, wherein in-situ destruction of contaminants is carried out rather than extracting contaminated fluids to the surface, where they are to be cleaned. In addition, the thermal treatment wall can be used for both plume interdiction and near-wellhead in-situ groundwater treatment. Thus, this technique can be utilized for a variety of groundwater contamination problems.

  19. Tunable thermal link

    DOE Patents [OSTI]

    Chang, Chih-Wei; Majumdar, Arunava; Zettl, Alexander K.

    2014-07-15

    Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

  20. Solar thermal aircraft

    DOE Patents [OSTI]

    Bennett, Charles L. (Livermore, CA)

    2007-09-18

    A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  1. Phase Change Materials for Thermal Energy Storage in Concentrated Solar Thermal Power Plants

    E-Print Network [OSTI]

    Hardin, Corey Lee

    2011-01-01

    and Background Solar thermal energy collection is anThermal Energy Storage in Concentrated Solar Thermal PowerThermal Energy Storage in Concentrated Solar Thermal Power

  2. GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, How pore fluid pressurization influences crack tip processes

    E-Print Network [OSTI]

    GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, How pore fluid pressurization temperature and pore pressure rises along a steadily propagating shear crack, assuming a given shear stress profile along the crack (i.e., initially neglecting effects of pore pressure on shear stress

  3. Thin Film Cracking Modulated by Underlayer Creep by J. Liang, R. Huang, J.H. Prvost, and Z. Suo

    E-Print Network [OSTI]

    Huang, Rui

    coatings in gas-turbine engines, and multilayers in medical implants.1­10 The applications typically ABSTRACT--In devices that integrate dissimilar materials in small dimensions, crack extension in one material often ac- companies inelastic deformation in another. In this paper we analyze a channel crack

  4. Evolution of crack-tip transformation zones in superelastic Nitinol subjected to in situ fatigue: A fracture mechanics

    E-Print Network [OSTI]

    Ritchie, Robert

    Evolution of crack-tip transformation zones in superelastic Nitinol subjected to in situ fatigue, Berkeley, CA 94720, USA b Stanford Synchrotron Radiation Laboratory, Menlo Park, CA 94025, USA c Nitinol of a growing fatigue crack (100 cycles in situ) in superelastic Nitinol. The results provide some surprising

  5. Mixed-Mode, High-Cycle Fatigue-Crack Growth Thresholds in Ti-6Al-4V

    E-Print Network [OSTI]

    Ritchie, Robert

    and control of failure due to high cycle fatigue (HCF) in turbine engine components is currently one and Engineering University of California, Berkeley, CA 94720-1760 ABSTRACT: There are few experimental results-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy

  6. Diffusion and Catalytic Cracking of 1,3,5 Tri-iso-propyl-benzene in FCC Catalysts

    E-Print Network [OSTI]

    Al-Khattaf, Sulaiman

    1 Diffusion and Catalytic Cracking of 1,3,5 Tri-iso- propyl-benzene in FCC Catalysts S.Al-Khattaf1 describes catalytic cracking experiments developed in a novel CREC Riser Simulator using 1,3,5-Tri-iso-propyl-benzene

  7. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone

    E-Print Network [OSTI]

    Ritchie, Robert

    The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical cortical bone Mixed-mode fracture Fracture toughness Crack-growth resistance curve a b s t r a c t The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading

  8. Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi, and John A. Nairn

    E-Print Network [OSTI]

    Nairn, John A.

    1 Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi In materials with process zones, such as fiber bridging zones in wood, it is crucial to characterize fracture toughness as a function of crack growth, known as the material's R curve. Here, a new fracture testing

  9. Thermally-related safety issues associated with thermal batteries.

    SciTech Connect (OSTI)

    Guidotti, Ronald Armand

    2006-06-01

    Thermal batteries can experience thermal runaway under certain usage conditions. This can lead to safety issues for personnel and cause damage to associated test equipment if the battery thermally self destructs. This report discusses a number of thermal and design related issues that can lead to catastrophic destruction of thermal batteries under certain conditions. Contributing factors are identified and mitigating actions are presented to minimize or prevent undesirable thermal runaway.

  10. Kernel regression estimates of time delays between gravitationally lensed fluxes

    E-Print Network [OSTI]

    Otaibi, Sultanah AL; Cuevas-Tello, Juan C; Mandel, Ilya; Raychaudhury, Somak

    2015-01-01

    Strongly lensed variable quasars can serve as precise cosmological probes, provided that time delays between the image fluxes can be accurately measured. A number of methods have been proposed to address this problem. In this paper, we explore in detail a new approach based on kernel regression estimates, which is able to estimate a single time delay given several datasets for the same quasar. We develop realistic artificial data sets in order to carry out controlled experiments to test of performance of this new approach. We also test our method on real data from strongly lensed quasar Q0957+561 and compare our estimates against existing results.

  11. Beta-delayed proton emission from $^{21}$Mg

    E-Print Network [OSTI]

    Lund, M V; Briz, J A; Cederkäll, J; Fynbo, H O U; Jensen, J H; Jonson, B; Laursen, K L; Nilsson, T; Perea, A; Pesudo, V; Riisager, K; Tengblad, O

    2015-01-01

    Beta-delayed proton emission from $^{21}$Mg has been measured at ISOLDE, CERN, with a detection setup including particle identification capabilities. $\\beta$-delayed protons with center of mass energies between 0.39$\\,$MeV and 7.2$\\,$MeV were measured and used to determine the half life of $^{21}$Mg as $118.6\\pm 0.5\\,$ms. From a line shape fit of the $\\beta p$ branches we extract spectroscopic information about the resonances of $^{21}$Na. Finally an improved interpretation of the decay scheme in accordance with the results obtained in reaction studies is presented.

  12. Before Mapping After Mapping Area Power Area Delay Power

    E-Print Network [OSTI]

    Pedram, Massoud

    32 Exam- ples Before Mapping After Mapping Area Power Area Delay Power 5xp1 0.93 0.98 0.86 0.82 0 1.01 1.01 1.02 1.07 0.99 duke2 1.01 1.01 0.99 1.13 0.97 e64 1.00 0.51 0.83 1.16 0.50 ex5 0.99 0.89 0.99 0.92 0.96 1.05 0.90 Table 2: Area, delay and power statistics for power script (normalized

  13. A review of carbide fuel corrosion for nuclear thermal propulsion applications

    SciTech Connect (OSTI)

    Pelaccio, D.G.; El-Genk, M.S. [Univ. of New Mexico, Albuquerque, NM (United States). Inst. for Space Nuclear Power Studies; Butt, D.P. [Los Alamos National Lab., NM (United States)

    1993-12-01

    At the operation conditions of interest in nuclear thermal propulsion reactors, carbide materials have been known to exhibit a number of life limiting phenomena. These include the formation of liquid, loss by vaporization, creep and corresponding gas flow restrictions, and local corrosion and fuel structure degradation due to excessive mechanical and/or thermal loading. In addition, the radiation environment in the reactor core can produce a substantial change in its local physical properties, which can produce high thermal stresses and corresponding stress fractures (cracking). Time-temperature history and cyclic operation of the nuclear reactor can also accelerate some of these processes. The University of New Mexico`s Institute for Space Nuclear Power Studies, under NASA sponsorship has recently initiated a study to model the complicated hydrogen corrosion process. In support of this effort, an extensive review of the open literature was performed, and a technical expert workshop was conducted. This paper summarizes the results of this review.

  14. Thermal Giant Gravitons

    E-Print Network [OSTI]

    Armas, Jay; Obers, Niels A; Orselli, Marta; Pedersen, Andreas Vigand

    2012-01-01

    We study the giant graviton solution as the AdS_5 X S^5 background is heated up to finite temperature. The analysis employs the thermal brane probe technique based on the blackfold approach. We focus mainly on the thermal giant graviton corresponding to a thermal D3-brane probe wrapped on an S^3 moving on the S^5 of the background at finite temperature. We find several interesting new effects, including that the thermal giant graviton has a minimal possible value for the angular momentum and correspondingly also a minimal possible radius of the S^3. We compute the free energy of the thermal giant graviton in the low temperature regime, which potentially could be compared to that of a thermal state on the gauge theory side. Moreover, we analyze the space of solutions and stability of the thermal giant graviton and find that, in parallel with the extremal case, there are two available solutions for a given temperature and angular momentum, one stable and one unstable. In order to write down the equations of mot...

  15. Multilayer thermal barrier coating systems

    DOE Patents [OSTI]

    Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

    2000-01-01

    The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

  16. Catalytic cracking. (Latest citations from the NTIS data base). Published Search

    SciTech Connect (OSTI)

    Not Available

    1992-05-01

    The bibliography contains citations concerning applications of catalytic cracking in fluidized beds, moving beds, refineries, vacuum distillation, and reformers. Design criteria, models, controls, and operating procedures are also discussed. (Contains 250 citations and includes a subject term index and title list.)

  17. Catalytic cracking. (Latest citations from the NTIS Bibliographic database). Published Search

    SciTech Connect (OSTI)

    Not Available

    1993-09-01

    The bibliography contains citations concerning applications of catalytic cracking in fluidized beds, moving beds, refineries, vacuum distillation, and reformers. Design criteria, models, controls, and operating procedures are also discussed. (Contains 250 citations and includes a subject term index and title list.)

  18. 128 CEREAL CHEMISTRY Effects of Alkali Debranning, Roller Mill Cracking and Gap Setting, and Alkali

    E-Print Network [OSTI]

    . Cracking the pericarp-free corn in a roller mill is done to further reduce kernel size so that steep time fiber, and gluten are separated. This procedure gave a practical compar- able starch yield of 67 was developed for the purpose of obtaining bran-free corn that was further processed into edible corn products

  19. THE INFLUENCE OF THE GRAIN STRUCTURE SIZE ON MICROSTRUCTURALLY SHORT CRACKS

    E-Print Network [OSTI]

    Cizelj, Leon

    ; crystal plasticity ABSTRACT The dominant processes in the initialization and propagation elasticity and crystal plasticity constitutive models are employed at the grain size scale. It is shown& strain rate tensor p kl& plastic strain rate tensoR crack direction ij stress tensor ij& stress rate

  20. Analysis of cracked piezoelectric solids by a mixed three-dimensional BE approach

    E-Print Network [OSTI]

    Ariza Moreno, Pilar

    regularization and evaluation of boundary integrals. Quadratic boundary elements and quarter-point boundary isotropy. Piezoelectric ceramics are used for construction of sensors, transducers, actuators as well, these brittle materials are likely to develop cracks. The under- standing and evaluation of the fracture process

  1. Analysis of the tube-sheet cracking in slurry oil steam , L.J. Qiao a,

    E-Print Network [OSTI]

    Volinsky, Alex A.

    , People's Republic of China b Jinzhou Petrochemical Corporation, China National Petroleum Corporation the tubes and the tube sheets, shown in Fig. 2. During the heat exchange process, the temperature analysis performed to simulate the hydraulic expansion process showed that this kind of cracking

  2. INFLUENCE OF HYDRIDE MICROSTRUCTURE ON THROUGH-THICKNESS CRACK GROWTH IN ZIRCALOY-4 SHEET

    E-Print Network [OSTI]

    Motta, Arthur T.

    1 INFLUENCE OF HYDRIDE MICROSTRUCTURE ON THROUGH-THICKNESS CRACK GROWTH IN ZIRCALOY-4 SHEET P. A and Engineering, The Pennsylvania State University, University Park, PA 16802 2 Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 3 Southwest Research

  3. Microstructure effect on hydrogen-induced cracking in TM210 maraging steel

    E-Print Network [OSTI]

    Volinsky, Alex A.

    August 2013 Keywords: Maraging steel Hydrogen embrittlement Reverted austenite Martensite lath boundaries formability. Solution- treated maraging steels have martensite with high dislocation density and a pronouncedMicrostructure effect on hydrogen-induced cracking in TM210 maraging steel Gang Wang a , Yu Yan

  4. Dynamics of fluid-filled gelatin cracks www.math.utwente.nl/bokhoveo/

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    Dynamics of fluid-filled gelatin cracks www.math.utwente.nl/bokhoveo/ Koji Kiyosugi, Onno Bokhove analog experiment, wherein gelatin is the elastic solid and water the intruding fluid: #12;Fluid cavity new dikes. Sketch of observations: gelatin gelatin frontal view 1 2 side view top view 32 32 1 1 1 3 2

  5. Radar interferometry for measuring tidal strains across cracks on David Sandwell,1

    E-Print Network [OSTI]

    Sandwell, David T.

    Radar interferometry for measuring tidal strains across cracks on Europa David Sandwell,1 Paul and the plate has been relatively thin ($2 km) [Carr et al., 1998]. However, the present-day average shell relationships and a variety of morphologic characteristics [Carr et al., 1998; Greenberg et al., 1998]. Simple

  6. Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler

    E-Print Network [OSTI]

    Bowler, John R.

    Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler The University 1994) Eddy-current inversion is the process whereby the geometry of a flaw in a metal is derived from eddy-current probe impedance measurements. The approach is based on an optimization scheme that seeks

  7. Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler

    E-Print Network [OSTI]

    Bowler, John R.

    Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler The University February 1994) The impedance of an eddy-current probe changes when the current it induces in an electrical to introduce idealizations about the nature of the flaw. Eddy-current interaction is considered with an ideal

  8. A protocol to develop crack-free biomimetic coatings on Ti6Al4V substrates

    E-Print Network [OSTI]

    Tas, A. Cuneyt

    A protocol to develop crack-free biomimetic coatings on Ti6Al4V substrates Sahil Jalota,a) Sutapa/Kadikoy, Istanbul 34755, Turkey (Received 22 November 2006; accepted 16 February 2007) Biomimetic coating in implantology. While this paper specifically refers to coating Ti6Al4V, the results are valid with other related

  9. Elastic-Plastic Models for Stable Crack Growtht *James R. Rice

    E-Print Network [OSTI]

    Elastic-Plastic Models for Stable Crack Growtht by *James R. Rice Mareh 1973 'PCAbh ~ ~ e c.\\. (n do not fully recover their strain upon unloading. The idealized non-linear elastic (left) and rigid-plastic,. there is ~ strain concentration created at the cut-ahead tip in the rigid-plastic material and the deformation field

  10. Geophys. J. Int. (2007) 000, 000000 Cracks, pulses and macroscopic asymmetry of dynamic rupture on a

    E-Print Network [OSTI]

    Ampuero, Jean Paul

    2007-01-01

    ruptures behave as cracks or pulses, decaying or sustained, bilateral or unilat- eral. With strongly stems from the difference in the criticality conditions for self-sustained propagation in each rupture architecture of a fault zone, bimaterial interfaces asso- ciated with rock damage are present with various

  11. NORTHWESTERN UNIVERSITY Crack Response of a Historic Structure to Weather Effects and

    E-Print Network [OSTI]

    of the rewards the relationship provides. My advisor Professor Charles Dowding is warmly thanked for his guidance and the "Indian house" on Garnett; and to the mixture of Beethoven, Satie, The Smashing Pumpkins, Mozart, Chopin;A mon père et au petit qui va naître. vi #12;Abstract Cosmetic cracks are very common in structures

  12. Numerical Green's Functions for Line Force and Dislocation around Multiple Cracks

    E-Print Network [OSTI]

    Denda, Mitsunori "Mitch"

    ) by the dislocation dipole distribution, embed the r crack tip behavior, and integrate the resulting singular/hyper are present in two-dimensional isotropic solids. Such Green's functions are called the numerical Green- tion and enabled the derivation of the Green's functions for more complex two- dimensional and three-dimensional

  13. Numerical modeling and experiments of creep crack growth under cyclic loading

    SciTech Connect (OSTI)

    Brust, F.W.

    1995-12-31

    This paper presents a summary of some recent studies of creep crack growth under history dependent load conditions. The effect of a proper constitutive law is illustrated. Moreover, the asymptotic fields are reconsidered under cyclic creep conditions. In addition, several experiments are modeled and the behavior of integral parameters is discussed.

  14. Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes

    E-Print Network [OSTI]

    Lapusta, Nadia

    Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes Xiao Lu , Nadia ruptures may propagate in a self-healing pulse-like mode. A number of expla- nations for the existence of slip pulses have been proposed and continue to be vigorously debated. This study presents experimen

  15. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    SciTech Connect (OSTI)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  16. Channel cracks in atomic-layer and molecular-layer deposited multilayer thin film coatings

    SciTech Connect (OSTI)

    Long, Rong, E-mail: rlongmech@gmail.com [Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Dunn, Martin L. [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Singapore University of Technology and Design, Singapore 138682 (Singapore)

    2014-06-21

    Metal oxide thin film coatings produced by atomic layer deposition have been shown to be an effective permeation barrier. The primary failure mode of such coatings under tensile loads is the propagation of channel cracks that penetrate vertically into the coating films. Recently, multi-layer structures that combine the metal oxide material with relatively soft polymeric layers produced by molecular layer deposition have been proposed to create composite thin films with desired properties, including potentially enhanced resistance to fracture. In this paper, we study the effects of layer geometry and material properties on the critical strain for channel crack propagation in the multi-layer composite films. Using finite element simulations and a thin-film fracture mechanics formalism, we show that if the fracture energy of the polymeric layer is lower than that of the metal oxide layer, the channel crack tends to penetrate through the entire composite film, and dividing the metal oxide and polymeric materials into thinner layers leads to a smaller critical strain. However, if the fracture energy of the polymeric material is high so that cracks only run through the metal oxide layers, more layers can result in a larger critical strain. For intermediate fracture energy of the polymer material, we developed a design map that identifies the optimal structure for given fracture energies and thicknesses of the metal oxide and polymeric layers. These results can facilitate the design of mechanically robust permeation barriers, an important component for the development of flexible electronics.

  17. Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jrme Fortin a

    E-Print Network [OSTI]

    Fortin, Jérôme

    Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jérôme Fortin a , Yves Guéguen-Sur-Cèze Cedex, France a r t i c l e i n f o Article history: Available online xxxx Keywords: Glass Pressure evolution of synthetic glass (SON68) under compressive triaxial stresses (hydrostatic and deviatoric

  18. A model for turbulent hydraulic fracture and application to crack propagation at glacier beds

    E-Print Network [OSTI]

    Tsai, Victor C.

    Click Here for Full Article A model for turbulent hydraulic fracture and application to crack suggest that fluidinduced hydraulic fracture of an ice sheet from its bed sometimes occurs quickly. Citation: Tsai, V. C., and J. R. Rice (2010), A model for turbulent hydraulic fracture and application

  19. A feasibility study of wind turbine blade surface crack detection using an optical inspection method

    E-Print Network [OSTI]

    McCalley, James D.

    A feasibility study of wind turbine blade surface crack detection using an optical inspection method Huiyi Zhang1 , John Jackman Wind Energy Manufacturing Laboratory Dept. of Industrial technique was investigated to assess its ability to detect surface flaws on an on-tower wind turbine blade

  20. Role of oxide thickening in fatigue crack initiation in LIGA nickel MEMS thin films

    E-Print Network [OSTI]

    Shan, Wanliang

    Role of oxide thickening in fatigue crack initiation in LIGA nickel MEMS thin films W.L. Shan a 2012 Accepted 16 October 2012 Available online 24 October 2012 Keywords: LIGA Ni MEMS thin films Oxide micro-electro-mechanical-systems (MEMS) structures. & 2012 Elsevier B.V. All rights reserved. 1

  1. Determining crack-tip stress-field parameters from mixed-mode displacement fields 

    E-Print Network [OSTI]

    Matsumoto, Kay Yuri

    1995-01-01

    that can develop at interfaces in composites and ceramics after prolonged exposure to elevated temperatures and adverse environments. The local crack-tip stress field in these cases will have a Mode II component even when the global loading is purely...

  2. Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking

    DOE Patents [OSTI]

    Steeves, Arthur F. (Schenectady, NY); Stewart, James C. (Loudonville, NY)

    1981-01-01

    A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

  3. The crystallography of fatigue crack initiation in Incoloy-908 and A-286 steel

    SciTech Connect (OSTI)

    Krenn, C.R. |

    1996-12-01

    Fatigue crack initiation in the austenitic Fe-Ni superalloys Incoloy-908 and A-286 is examined using local crystallographic orientation measurements. Results are consistent with sharp transgranular initiation and propagation occurring almost exclusively on {l_brace}111{r_brace} planes in Incoloy-908 but on a variety of low index planes in A-286. This difference is attributed to the influence of the semicoherent grain boundary {eta} phase in A-286. Initiation in each alloy occurred both intergranularly and transgranularly and was often associated with blocky surface oxide and carbide inclusions. Taylor factor and resolved shear stress and strain crack initiation hypotheses were tested, but despite an inconclusive suggestion of a minimum required {l_brace}111{r_brace} shear stress, none of the hypotheses were found to convincingly describe preferred initiation sites, even within the subsets of transgranular cracks apparently free from the influence of surface inclusions. Subsurface inclusions are thought to play a significant role in crack initiation. These materials have applications for use in structural conduit for high field superconducting magnets designed for fusion energy use.

  4. Biomaterials 26 (2005) 11951204 Mechanistic aspects of in vitro fatigue-crack growth in dentin

    E-Print Network [OSTI]

    Ritchie, Robert O.

    2005-01-01

    Biomaterials 26 (2005) 1195­1204 Mechanistic aspects of in vitro fatigue-crack growth in dentin J,13]. These notches are often the ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2004.04.051 ÃCorresponding

  5. Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube for endovascular stents

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube Nitinol has found widespread application in the manufacture of small-scale biomedical devices of defects on such lifetimes. Unfortunately, frac- ture mechanics studies on fatigue in Nitinol are scarce

  6. Standard test method for crack-tip opening displacement (CTOD) fracture toughness measurement

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the determination of critical crack-tip opening displacement (CTOD) values at one or more of several crack extension events, and may be used to measure cleavage crack initiation toughness for materials that exhibit a change from ductile to brittle behavior with decreasing temperature, such as ferritic steels. This test method applies specifically to notched specimens sharpened by fatigue cracking. The recommended specimens are three-point bend [SE(B)], compact [C(T)], or arc-shaped bend [A(B)] specimens. The loading rate is slow and influences of environment (other than temperature) are not covered. The specimens are tested under crosshead or clip gage displacement controlled loading. 1.1.1 The recommended specimen thickness, B, for the SE(B) and C(T) specimens is that of the material in thicknesses intended for an application. For the A(B) specimen, the recommended depth, W, is the wall thickness of the tube or pipe from which the specimen is obtained. Superficial surface machini...

  7. A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED MATERIALS and fracture toughness; Metals; Structural ceramics; Precracks Introduction Functionally graded materials (FGMs) containing metallic and ceramic phases offer a viable solution to modern design problems requiring structural

  8. ON THE FATIGUE BEHAVIOR OF g-BASED TITANIUM ALUMINIDES: ROLE OF SMALL CRACKS

    E-Print Network [OSTI]

    Ritchie, Robert

    attention for potential elevated temperature ap- plications in gas-turbine engines. However, although expected critical crack sizes for some targeted appli- cations (e.g. gas-turbine engine blades) may be less applications [1, 2]. In comparison to conven- tional gas-turbine engine materials [1±4], titanium aluminides

  9. Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions

    SciTech Connect (OSTI)

    Muhlstein, C.L.; Howe, R.T.; Ritchie, R.O.

    2001-12-05

    Although bulk silicon is not known to exhibit susceptibility to cyclic fatigue, micron-scale structures made from silicon films are known to be vulnerable to degradation by fatigue in ambient air environments, a phenomenon that has been recently modeled in terms of a mechanism of sequential oxidation and stress-corrosion cracking of the native oxide layer.

  10. CHARACTERISATION OF AGED HDPE PIPES FROM DRINKING WATER DISTRIBUTION: INVESTIGATION OF CRACK DEPTH BY NOL RING

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    BY NOL RING TESTS UNDER CREEP LOADING C. Devilliers 1), 2), 3) , L. Laiarinandrasana 1) , B. Fayolle 2. KEYWORDS HDPE pipes, Nol Ring creep test, ageing effects, fracture mechanism, crack depth ratio, aged layer loading than a monotonic tensile loading. It is to be noticed that the Nol Ring test subjected to a creep

  11. A creep model for austenitic stainless steels incorporating cavitation and wedge cracking

    E-Print Network [OSTI]

    Mahesh, Sivasambu

    A creep model for austenitic stainless steels incorporating cavitation and wedge cracking S Mahesh, Kalpakkam 603102. India Abstract. A model of damage evolution in austenitic stainless steels under creep experimental data for a type 316 austenitic stainless steel under uniaxial creep loading. Deformation

  12. Stainless steel pitting and early-stage stress corrosion cracking under ultra-low elastic load

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Stainless steel pitting and early-stage stress corrosion cracking under ultra-low elastic load Available online 7 September 2013 Keywords: A. Stainless steel B. SEM B. Modeling studies C. Stress] in stainless steel (SS), are key factors inducing the preferential pitting initiation. For homoge- neous

  13. Using Crack Propagation Fracture Toughness to Characterize the Durability of Wood and Wood Composites

    E-Print Network [OSTI]

    Nairn, John A.

    Using Crack Propagation Fracture Toughness to Characterize the Durability of Wood and Wood, Corvallis, OR 97330, USA Abstract We measured fracture resistance curves (or R curves) for laminated veneer. The LVL and solid wood R curves were the same for initiation of fracture, but the LVL toughness rose much

  14. Results of crack-arrest tests on irradiated a 508 class 3 steel

    SciTech Connect (OSTI)

    Iskander, S.K.; Milella, P.P.; Pini, M.A.

    1998-02-01

    Ten crack-arrest toughness values for irradiated specimens of A 508 class 3 forging steel have been obtained. The tests were performed according to the American Society for Testing and Materials (ASTM) Standard Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, K{sub la} of Ferritic Steels, E 1221-88. None of these values are strictly valid in all five ASTM E 1221-88 validity criteria. However, they are useful when compared to unirradiated crack-arrest specimen toughness values since they show the small (averaging approximately 10{degrees}C) shifts in the mean and lower-bound crack-arrest toughness curves. This confirms that a low copper content in ASTM A 508 class 3 forging material can be expected to result in small shifts of the transition toughness curve. The shifts due to neutron irradiation of the lower bound and mean toughness curves are approximately the same as the Charpy V-notch (CVN) 41-J temperature shift. The nine crack-arrest specimens were irradiated at temperatures varying from 243 to 280{degrees}C, and to a fluence varying from 1.7 to 2.7 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV). The test results were normalized to reference values that correspond to those of CVN specimens irradiated at 284{degrees}C to a fluence of 3.2 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV) in the same capsule as the crack-arrest specimens. This adjustment resulted in a shift to lower temperatures of all the data, and in particular moved two data points that appeared to lie close to or lower than the American Society of Mechanical Engineers K{sub la} curve to positions that seemed more reasonable with respect to the remaining data. A special fixture was designed, fabricated, and successfully used in the testing. For reasons explained in the text, special blocks to receive the Oak Ridge National Laboratory clip gage were designed, and greater-than-standard crack-mouth opening displacements measured were accounted for. 24 refs., 13 figs., 12 tabs.

  15. ht.I. EngngSri.1975,Vol.13,pp.815-829.PcrgamonPress. Printedin GrealBritain THE PENNY-SHAPED CRACK IN SHEAR AND

    E-Print Network [OSTI]

    Barber, James R.

    ht.I. EngngSri.1975,Vol.13,pp.815-829.PcrgamonPress. Printedin GrealBritain THE PENNY-SHAPED CRACK. The solution is used to solve the problem of the penny-shaped crack subjected to an arbitrary and to the penny-shaped crack inuniformshearandintorsionabouta diametralaxis. 1. INTRODUCTION IN A PREVIOUS paper

  16. Delay Analysis of Combined Input-Crosspoint Queueing Switches

    E-Print Network [OSTI]

    Hamdi, Mounir

    Delay Analysis of Combined Input-Crosspoint Queueing Switches Ge Nong, Ning Situ and Mounir Hamdi Abstract-- The switch architecture with the combined input- crosspoint queueing (CICQ) scheme has been recognized as a practical promising solution for building cost-effective high- performance switches. In an N

  17. Time Delay Plot for Pion-Nucleon Elastic Scattering

    E-Print Network [OSTI]

    Mohamed E. Kelabi

    2012-01-14

    We evaluated the time delay plot in the established region of the Delta(1232) resonance through the use of elastic scattering phase shift analysis of the partial wave amplitude P33. The pole position and width of the Delta(1232) resonance were obtained and found in agreement with earlier calculations.

  18. Delayed Development of Pneumothorax After Pulmonary Radiofrequency Ablation

    SciTech Connect (OSTI)

    Clasen, Stephan, E-mail: stephan.clasen@med.uni-tuebingen.d [Eberhard-Karls-University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany); Kettenbach, Joachim [Medical University of Vienna, Cardiovascular and Interventional Radiology, Department of Radiology (Austria); Kosan, Bora; Aebert, Hermann [Eberhard-Karls-University of Tuebingen, Department of Thoracic, Cardiac and Vascular Surgery (Germany); Schernthaner, Melanie [Medical University of Vienna, Cardiovascular and Interventional Radiology, Department of Radiology (Austria); Kroeber, Stefan-Martin [Eberhard-Karls-University of Tuebingen, Institute of Pathology (Germany); Boemches, Andrea [Eberhard-Karls-University of Tuebingen, Department of Thoracic, Cardiac and Vascular Surgery (Germany); Claussen, Claus D.; Pereira, Philippe L. [Eberhard-Karls-University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany)

    2009-05-15

    Acute pneumothorax is a frequent complication after percutaneous pulmonary radiofrequency (RF) ablation. In this study we present three cases showing delayed development of pneumothorax after pulmonary RF ablation in 34 patients. Our purpose is to draw attention to this delayed complication and to propose a possible approach to avoid this major complication. These three cases occurred subsequent to 44 CT-guided pulmonary RF ablation procedures (6.8%) using either internally cooled or multitined expandable RF electrodes. In two patients, the pneumothorax, being initially absent at the end of the intervention, developed without symptoms. One of these patients required chest drain placement 32 h after RF ablation, and in the second patient therapy remained conservative. In the third patient, a slight pneumothorax at the end of the intervention gradually increased and led into tension pneumothorax 5 days after ablation procedure. Underlying bronchopleural fistula along the coagulated former electrode track was diagnosed in two patients. In conclusion, delayed development of pneumothorax after pulmonary RF ablation can occur and is probably due to underlying bronchopleural fistula, potentially leading to tension pneumothorax. Patients and interventionalists should be prepared for delayed onset of this complication, and extensive track ablation following pulmonary RF ablation should be avoided.

  19. Efficient Path Delay Test Generation with Boolean Satisfiability 

    E-Print Network [OSTI]

    Bian, Kun

    2013-12-10

    This dissertation focuses on improving the accuracy and efficiency of path delay test generation using a Boolean satisfiability (SAT) solver. As part of this research, one of the most commonly used SAT solvers, MiniSat, was integrated into the path...

  20. Delayed energy injection model for gamma-ray burst afterglows

    SciTech Connect (OSTI)

    Geng, J. J.; Huang, Y. F.; Yu, Y. B. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: hyf@nju.edu.cn, E-mail: xfwu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-12-10

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ?t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  1. Predictive Control for Time-Delayed Switching Control Systems

    E-Print Network [OSTI]

    Barth, Eric J.

    Predictive Control for Time-Delayed Switching Control Systems Bobby L. Shields Eric J. Barth A methodology is proposed for the control of switching systems characterized by linear system dynamics period determines the effect that the next control input will have on the future output of the system

  2. BIFURCATIONS IN A CAR-FOLLOWING MODEL WITH DELAY

    E-Print Network [OSTI]

    Awtar, Shorya

    BIFURCATIONS IN A CAR-FOLLOWING MODEL WITH DELAY G´abor Orosz , R. Eddie Wilson , Bernd Krauskopf of Bristol, Bristol BS8 1TR, United Kingdom Abstract: A simple car-following model that includes the reaction time of drivers is analyzed by numerical continuation techniques for the case of five cars on a ring

  3. Admission Control Framework to Provide Guaranteed Delay in Errorprone Wireless

    E-Print Network [OSTI]

    Sarkar, Saswati

    1 Admission Control Framework to Provide Guaranteed Delay in Error­prone Wireless Channel Prasanna Chaporkar and Saswati Sarkar Abstract We consider a wireless system in which sessions traverse different­prone wireless system. By ``general'' we mean that the scheduling policies from a large class can be plugged

  4. Fast amplitude and delay measurement for characterization of optical devices 

    E-Print Network [OSTI]

    Thompson, Michael Thomas

    2006-10-30

    of the measured magnitude response of an Acetylene gas cell and comparing it to the integral of the measured group delay. The average deviation between the two methods is 0.1 radians. An Acetylene gas cell, fiber Bragg grating, and chirped Bragg grating are tested...

  5. Delay Optimal Scheduling for Energy Harvesting Based Communications

    E-Print Network [OSTI]

    Dai, Huaiyu

    1 Delay Optimal Scheduling for Energy Harvesting Based Communications Juan Liu, Huaiyu Dai, Senior research interest recently. Equipped with a rechargeable battery, a source node can harvest energy from ambient environments and rely on this free and regenerative energy supply to transmit packets. Due

  6. Delay Fast Packets (DFP): Prevention of DNS Cache Poisoning

    E-Print Network [OSTI]

    Dolev, Danny

    Delay Fast Packets (DFP): Prevention of DNS Cache Poisoning Shimrit Tzur-David Kiril Lashchiver, or any other network resource. This paper presents a solution for the cache poisoning attack in which the attacker inserts incorrect data into the DNS cache. In order to successfully poison the cache, the attacker

  7. Minimum Delay Communication in Energy Harvesting Systems over Fading Channels

    E-Print Network [OSTI]

    Laneman, J. Nicholas

    by the data where the average is taken over all the random processes in our system, i.e, data arrival, energyMinimum Delay Communication in Energy Harvesting Systems over Fading Channels Mostafa Khoshnevisan, Indiana 46556 Email:{mkhoshne, jnl}@nd.edu Abstract--We consider an energy harvesting wireless system

  8. On Churn and Communication Delays in Social Overlays

    E-Print Network [OSTI]

    Montresor, Alberto

    On Churn and Communication Delays in Social Overlays Giuliano Mega, Alberto Montresor, and Gian. Yet, the churn induced by the availability of users raises the question--still unanswered--of whether the overlay in the presence of churn. This paper puts forth two contributions. First, we show through

  9. GLOBAL STABILITY IN CHEMOSTAT-TYPE EQUATIONS WITH DISTRIBUTED DELAYS

    E-Print Network [OSTI]

    Ruan, Shigui

    recycled after the death of the biomass by bacterial decomposition, and the second delay indicates process, thus neglecting the time required to regenerate the nutrient from the dead biomass by bacterial chemostat ex- periments with microalgae Chlamidomonas Reinhardii even when the limiting nutrient

  10. Delayed Afterglow Onset Interpreted as Baryon-Poor Viewing Angle

    E-Print Network [OSTI]

    David Eichler

    2005-03-24

    We have suggested previously that baryons in GRB fireballs infiltrate from the surrounding walls that collimate the fireball. The efficiency $\\epsilon_b$ for generating blast energy can then be angle dependent. Delayed onset of afterglow can be interpreted as being due to a baryon-poor viewing angle.

  11. Delayed neutron measurements from fast fission of actinide waste isotopes 

    E-Print Network [OSTI]

    Charlton, William S.

    1997-01-01

    quick pneumatic transfer system, an integrated computer control and counting system, and a specially designed in-core irradiation device. The values for the total delayed neutron yield (per 100 fissions) from fast-neutron induced fission of U-235, Np237...

  12. Modeling a Snap-Action, Variable-Delay Switch

    E-Print Network [OSTI]

    Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America, 2, Cambridge, Massachusetts, United States of America When exposed to tumor necrosis factor (TNF) or TNFModeling a Snap-Action, Variable-Delay Switch Controlling Extrinsic Cell Death John G. Albeck1

  13. Thermally Polymerized Rylene Nanoparticles

    E-Print Network [OSTI]

    Andrew, Trisha Lionel

    Rylene dyes functionalized with varying numbers of phenyl trifluorovinyl ether (TFVE) moieties were subjected to a thermal emulsion polymerization to yield shape-persistent, water-soluble chromophore nanoparticles. Perylene ...

  14. Thermal Insulation Systems 

    E-Print Network [OSTI]

    Stanley, T. F.

    1982-01-01

    Thermal insulation systems are receiving a high degree of attention in view of increasing energy cost. Industrial, commercial and residential energy users are all well aware of energy cost increases and great emphasis is being directed to energy...

  15. Contact thermal lithography

    E-Print Network [OSTI]

    Schmidt, Aaron Jerome, 1979-

    2004-01-01

    Contact thermal lithography is a method for fabricating microscale patterns using heat transfer. In contrast to photolithography, where the minimum achievable feature size is proportional to the wavelength of light used ...

  16. Photovoltaic-thermal collectors

    DOE Patents [OSTI]

    Cox, III, Charles H. (Carlisle, MA)

    1984-04-24

    A photovoltaic-thermal solar cell including a semiconductor body having antireflective top and bottom surfaces and coated on each said surface with a patterned electrode covering less than 10% of the surface area. A thermal-absorbing surface is spaced apart from the bottom surface of the semiconductor and a heat-exchange fluid is passed between the bottom surface and the heat-absorbing surface.

  17. Thermal Resonance Fusion

    E-Print Network [OSTI]

    Bao-Guo Dong

    2015-07-07

    We first show a possible mechanism to create a new type of nuclear fusion, thermal resonance fusion, i.e. low energy nuclear fusion with thermal resonance of light nuclei or atoms, such as deuterium or tritium. The fusion of two light nuclei has to overcome the Coulomb barrier between these two nuclei to reach up to the interacting region of nuclear force. We found nuclear fusion could be realized with thermal vibrations of crystal lattice atoms coupling with light atoms at low energy by resonance to overcome this Coulomb barrier. Thermal resonances combining with tunnel effects can greatly enhance the probability of the deuterium fusion to the detectable level. Our low energy nuclear fusion mechanism research - thermal resonance fusion mechanism results demonstrate how these light nuclei or atoms, such as deuterium, can be fused in the crystal of metal, such as Ni or alloy, with synthetic thermal vibrations and resonances at different modes and energies experimentally. The probability of tunnel effect at different resonance energy given by the WKB method is shown that indicates the thermal resonance fusion mode, especially combined with the tunnel effect, is possible and feasible. But the penetrating probability decreases very sharply when the input resonance energy decreases less than 3 keV, so for thermal resonance fusion, the key point is to increase the resonance peak or make the resonance sharp enough to the acceptable energy level by the suitable compound catalysts, and it is better to reach up more than 3 keV to make the penetrating probability larger than 10^{-10}.

  18. Carbon fiber composite characterization in adverse thermal environments.

    SciTech Connect (OSTI)

    Gomez-Vasquez, Sylvia; Brown, Alexander L.; Hubbard, Joshua A.; Ramirez, Ciro J.; Dodd, Amanda B.

    2011-05-01

    The behavior of carbon fiber aircraft composites was studied in adverse thermal environments. The effects of resin composition and fiber orientation were measured in two test configurations: 102 by 127 millimeter (mm) test coupons were irradiated at approximately 22.5 kW/m{sup 2} to measure thermal response, and 102 by 254 mm test coupons were irradiated at approximately 30.7 kW/m{sup 2} to characterize piloted flame spread in the vertically upward direction. Carbon-fiber composite materials with epoxy and bismaleimide resins, and uni-directional and woven fiber orientations, were tested. Bismaleimide samples produced less smoke, and were more resistant to flame spread, as expected for high temperature thermoset resins with characteristically lower heat release rates. All materials lost approximately 20-25% of their mass regardless of resin type, fiber orientation, or test configuration. Woven fiber composites displayed localized smoke jetting whereas uni-directional composites developed cracks parallel to the fibers from which smoke and flames emanated. Swelling and delamination were observed with volumetric expansion on the order of 100% to 200%. The purpose of this work was to provide validation data for SNL's foundational thermal and combustion modeling capabilities.

  19. Vitrification of lead-based paint using thermal spray

    SciTech Connect (OSTI)

    Kumar, A.; Covey, S.W.; Lattimore, J.L.; Boy, J.H.

    1996-12-31

    Lead-based paint (LBP) primers have been used to protect steel structures from corrosion. Abrasive blasting is currently used to remove old LBP. During abrasive blasting a containment structure is required to keep the hazardous lead dust from contaminating air, soil, or water. A thermal spray vitrification (TSV) process to remove LBP was developed. Dried glass powder is melted in the high temperature flame of the thermal spray torch. When the glass strikes the substrate it is molten and reacts with the paint on the substrate. The organic components of the paint are pyrolyzed, while the lead ions are trapped on the surface of glass. The quenching stresses in the glass cause the glass to crack and spall off the substrate. The crumbled glass fragments can be collected and remelted, immobilizing the lead ions within the glass network, thereby preventing leaching. The resulting glass can be disposed of as non-hazardous waste. The process is dust-free, eliminating the need for containment. The volume of residue waste is less than for abrasive blasting and is nonhazardous. The concept and techniques of using the thermal spray vitrification process for the removal and the containment of lead from a section of a bridge containing lead-based paint have been successfully demonstrated.

  20. Thermal cycling tests on surface-mount assemblies

    SciTech Connect (OSTI)

    Jennings, C.W.

    1988-03-01

    The capability of surface-mount (SM) solder joints to withstand various thermal cycle stresses was evaluated through electrical circuit resistance changes of a test pattern and by visual examination for cracks in the solder after exposure to thermal cycling. The joints connected different electrical components, primarily leadless-chip carriers (LCCs), and printed wiring-board (PWB) pads on different laminate substrates. Laminate compositions were epoxy-glass and polyimide-glass with and without copper/Invar/copper (CIC) inner layers, polyimide-quartz, epoxy-Kevlar, and polyimide-Kevlar. The most resistant joints were between small LCCs (24 and 48 pins) and polyimide-glass laminate with CIC inner layers. Processing in joint formation was found to be an important part of joint resistant. Thermal cycling was varied with respect to both time and temperature. A few resistors, capacitors, and inductors showed opens after 500 30-min cycles between -65/degree/C and 125/degree/C. Appreciable moisture contents were measured for laminate materials, especially those of polyimide-Kevlar after equilibration in 100/percent/ relative humidity at room temperature. If not removed or reduced, moisture can cause delamination in vapor-phase soldering. 17 refs, 12 figs.,10 tabs.

  1. Thermal Resonance Fusion

    E-Print Network [OSTI]

    Dong, Bao-Guo

    2015-01-01

    We first show a possible mechanism to create a new type of nuclear fusion, thermal resonance fusion, i.e. low energy nuclear fusion with thermal resonance of light nuclei or atoms, such as deuterium or tritium. The fusion of two light nuclei has to overcome the Coulomb barrier between these two nuclei to reach up to the interacting region of nuclear force. We found nuclear fusion could be realized with thermal vibrations of crystal lattice atoms coupling with light atoms at low energy by resonance to overcome this Coulomb barrier. Thermal resonances combining with tunnel effects can greatly enhance the probability of the deuterium fusion to the detectable level. Our low energy nuclear fusion mechanism research - thermal resonance fusion mechanism results demonstrate how these light nuclei or atoms, such as deuterium, can be fused in the crystal of metal, such as Ni or alloy, with synthetic thermal vibrations and resonances at different modes and energies experimentally. The probability of tunnel effect at dif...

  2. Low Thermal Conductivity, High Durability Thermal Barrier Coatings for IGCC Environments

    SciTech Connect (OSTI)

    Jordan, Eric; Gell, Maurice

    2015-01-15

    Advanced thermal barrier coatings (TBC) are crucial to improved energy efficiency in next generation gas turbine engines. The use of traditional topcoat materials, e.g. yttria-stabilized zirconia (YSZ), is limited at elevated temperatures due to (1) the accelerated undesirable phase transformations and (2) corrosive attacks by calcium-magnesium-aluminum-silicate (CMAS) deposits and moisture. The first goal of this project is to use the Solution Precursor Plasma Spray (SPPS) process to further reduce the thermal conductivity of YSZ TBCs by introducing a unique microstructural feature of layered porosity, called inter-pass boundaries (IPBs). Extensive process optimization accompanied with hundreds of spray trials as well as associated SEM cross-section and laser-flash measurements, yielded a thermal conductivity as low as 0.62 Wm?¹K?¹ in SPPS YSZ TBCs, approximately 50% reduction of APS TBCs; while other engine critical properties, such as cyclic durability, erosion resistance and sintering resistance, were characterized to be equivalent or better than APS baselines. In addition, modifications were introduced to SPPS TBCs so as to enhance their resistance to CMAS under harsh IGCC environments. Several mitigation approaches were explored, including doping the coatings with Al?O? and TiO?, applying a CMAS infiltration-inhibiting surface layer, and filling topcoat cracks with blocking substances. The efficacy of all these modifications was assessed with a set of novel CMAS-TBC interaction tests, and the moisture resistance was tested in a custom-built high-temperature moisture rig. In the end, the optimal low thermal conductivity TBC system was selected based on all evaluation tests and its processing conditions were documented. The optimal coating consisted on a thick inner layer of YSZ coating made by the SPPS process having a thermal conductivity 50% lower than standard YSZ coatings topped with a high temperature tolerant CMAS resistant gadolinium zirconate Coating made by the SPPS process. Noteworthy was the fact that the YSZ to GZO interface made by the SPPS process was not the failure location as had been observed in APS coatings.

  3. Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress

    E-Print Network [OSTI]

    Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress Anthony J. Bellantuono1 thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant) maintained

  4. Preliminary Simulations for Geometric Optimization of a High-Energy Delayed Gamma Spectrometer for Direct Assay of Pu in Spent Nuclear Fuel

    SciTech Connect (OSTI)

    Kulisek, Jonathan A.; Campbell, Luke W.; Rodriguez, Douglas C.

    2012-06-07

    High-energy, beta-delayed gamma-ray spectroscopy is under investigation as part of the Next Generation Safeguard Initiative effort to develop non-destructive assay instruments for plutonium mass quantification in spent nuclear fuel assemblies. Results obtained to date indicate that individual isotope-specific signatures contained in the delayed gamma-ray spectra can potentially be used to quantify the total fissile content and individual weight fractions of fissile and fertile nuclides present in spent fuel. Adequate assay precision for inventory analysis can be obtained using a neutron generator of sufficient strength and currently available detection technology. In an attempt to optimize the geometric configuration and material composition for a delayed gamma measurement on spent fuel, the current study applies MCNPX, a Monte Carlo radiation transport code, in order to obtain the best signal-to-noise ratio. Results are presented for optimizing the neutron spectrum tailoring material, geometries to maximize thermal or fast fissions from a given neutron source, and detector location to allow an acceptable delayed gamma-ray signal while achieving a reasonable detector lifetime while operating in a high-energy neutron field. This work is supported in part by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

  5. In-Line Crack and Stress Detection in Silicon Solar Cells Using Resonance Ultrasonic Vibrations

    SciTech Connect (OSTI)

    Ostapenko, Sergei

    2013-04-03

    Statement of Problem and Objectives. Wafer breakage in automated solar cell production lines is identified as a major technical problem and a barrier for further cost reduction of silicon solar module manufacturing. To the best of our knowledge, there are no commercial systems addressing critical needs for in-line inspection of the mechanical quality of solar wafers and cells. The principal objective of the SBIR program is to validate through experiments and computer modeling the applicability of the Resonance Ultrasonic Vibrations system, which ultimately can be used as a real-time in-line manufacturing quality control tool for fast detection of mechanically unstable silicon solar cells caused by cracks. The specific objective of Phase II is to move the technology of in-line crack detection from the laboratory level to commercial demonstration through development of a system prototype. The fragility of silicon wafers possessing low mechanical strength is attributed to peripheral and bulk millimeter-length cracks. The research program is based on feasibility results obtained during Phase I, which established that: (i) the Resonance Ultrasonic Vibrations method is applicable to as-cut, processed wafers and finished cells; (ii) the method sensitivity depends on the specific processing step; it is highest in as-cut wafers and lowest in wafers with metallization pattern and grid contacts; (iii) the system is capable of matching the 2.0 seconds per wafer throughput rate of state-of-art solar cell production lines; (iv) finite element modeling provides vibration mode analysis along with peak shift versus crack length and crack location dependence; (v) a high 91% crack rejection rate was confirmed through experimentation and statistical analysis. The Phase II project has the following specific tasks: (i) specify optimal configurations of the in-line system�¢����s component hardware and software; (ii) develop and justify a system prototype that meets major specifications for an in-line crack detection unit, such as high throughput rate, high level of stability, reproducibility of data acquisition and analysis, and high sensitivity with respect to crack length and crack location; (iii) design a system platform that allows easy integration within and adaptation to various solar cell belt-type production lines; (iv) develop a testing protocol providing quality certification of the production-grade system. Commercial Application of the proposed activity consists of bringing to the solar market a new high-tech product based on an innovative solution and patented methodology to contribute to cost reduction of silicon solar module production. The solar industry, with crystalline silicon as a dominant segment, shows outstanding performance, with approximately 25% yearly growth during the last years. Despite a slowdown with only 5.6 GW installations in 2009, solar module production for the 2010 and 2011 years was recovered. According to European Photonics Industry Consortium new solar PV installations grow by 56% compared to 2010 reached 64.7 GW in 2011. Revenues in the PV industry reached a record high of $93 billion in 2011, a 13.4 percent gain over 2010 â�� and 150 percent over 2009. This growth was forecasted to continue in 2013 with double digits growth. The solar industry is economically driven to make solar panels of the highest conversion efficiency and reliability at the lowest production cost. The Resonance Ultrasonic Vibration system addresses critical needs of the silicon-based solar industry by providing a quality control method and tool, which will improve productivity, increase reliability of products and reduce manufacturing cost of solar panels.

  6. Simulation and Experiment of Thermal Fatigue in the CPV Die Attach: Preprint

    SciTech Connect (OSTI)

    Bosco, N.; Silverman, T.; Kurtz, S.

    2012-05-01

    FEM simulation and accelerated thermal cycling have been performed for the CPV die attach. Trends in fatigue damage accumulation and equivalent test time are explored and found to be most sensitive to temperature ramp rate. Die attach crack growth is measured through cycling and found to be in excellent agreement with simulations of the inelastic strain energy accumulated. Simulations of an entire year of weather data provides for the relative ranking of fatigue damage between four cites as well as their equivalent accelerated test time.

  7. Thermal Lens Spectroscopy Mladen Franko

    E-Print Network [OSTI]

    Reid, Scott A.

    Thermal Lens Spectroscopy Mladen Franko Laboratory of Environmental Research, University of Nova-beam Instruments 5 3.3 Differential Thermal Lens Instruments 7 3.4 Multiwavelength and Tunable Thermal Lens Spectrometers 8 3.5 Circular Dichroism TLS Instruments 9 3.6 Miniaturization of Thermal Lens Instruments 9 4

  8. The effect of in-situ noble metal chemical addition on crack growth rate behavior of structural materials in 288 C water

    SciTech Connect (OSTI)

    Andresen, P.L.; Angeliu, T.

    1996-10-01

    Stress corrosion cracking (SCC), especially in existing boiling water reactor (BVM) components, is most effectively accomplished by reducing the corrosion potential. This was successfully demonstrated by adding hydrogen to BNM water, which reduced oxidant concentration and corrosion potential by recombining with the radiolytically formed oxygen and hydrogen peroxide. However, reduction in the corrosion potential for some vessel internals is difficult, and others require high hydrogen addition rates, which results in an increase in the main steam radiation level from volatile N{sup 16}. Noble metal electrocatalysis provides a unique opportunity to efficiently achieve a dramatic reduction in corrosion potential and SCC in BWRs, by catalytically reacting all oxidants that diffuse to a (catalytic) metal surface with hydrogen. There are many techniques for creating catalytic surfaces, including alloying with noble metals or applying noble metal alloy powders to existing BWR components by thermal spraying or weld cladding. A novel system-wide approach for producing catalytic surfaces on all wetted components has been developed which employs the reactor coolant water as the medium of transport. This approach is termed in-situ noble metal chemical addition (NMCA), and has been successfully used in extensive laboratory tests to coat a wide range of pre-oxidized structural materials. In turn, these specimens have maintained catalytic response in long term, cyclic exposures to extremes in dissolved gases, impurity levels, pH, flow rate, temperature, straining, etc. With stoichiometric excess H{sub 2}, the corrosion potential drops dramatically and crack initiation and growth are greatly reduced, even at high O{sub 2} or H{sub 2}O{sub 2} levels. Without excess H{sub 2} (i.e., in normal BWR water chemistry), noble metals do not increase the corrosion potential or SCC.

  9. Radiation-induced instability of MnS precipitates and its possible consequences on irradiation-induced stress corrosion cracking of austenitic stainless steels

    SciTech Connect (OSTI)

    Chung, H.M.; Sanecki, J.E.; Garner, F.A.

    1996-12-01

    Irradiation-assisted stress corrosion cracking (IASCC) is a significant materials issue for the light water reactor (LWR) industry and may also pose a problem for fusion power reactors that will use water as coolant. A new metallurgical process is proposed that involves the radiation-induced release into solution of minor impurity elements not usually thought to participate in IASCC. MnS-type precipitates, which contain most of the sulfur in stainless steels, are thought to be unstable under irradiation. First, Mn transmutes strongly to Fe in thermalized neutron spectra. Second, cascade-induced disordering and the inverse Kirkendall effect operating at the incoherent interfaces of MnS precipitates are thought to act as a pump to export Mn from the precipitate into the alloy matrix. Both of these processes will most likely allow sulfur, which is known to exert a deleterious influence on intergranular cracking, to re-enter the matrix. To test this hypothesis, compositions of MnS-type precipitates contained in several unirradiated and irradiated heats of Type 304, 316, and 348 stainless steels (SSs) were analyzed by Auger electron spectroscopy. Evidence is presented that shows a progressive compositional modification of MnS precipitates as exposure to neutrons increases in boiling water reactors. As the fluence increases, the Mn level in MnS decreases, whereas the Fe level increases. The S level also decreases relative to the combined level of Mn and Fe. MnS precipitates were also found to be a reservoir of other deleterious impurities such as F and O which could be also released due to radiation-induced instability of the precipitates.

  10. Analysis of atmospheric delays and asymmetric positioning errors in the global positioning system

    E-Print Network [OSTI]

    Materna, Kathryn

    2014-01-01

    Abstract Errors in modeling atmospheric delays are one of the limiting factors in the accuracy of GPS position determination. In regions with uneven topography, atmospheric delay phenomena can be especially complicated. ...

  11. Environmentally assisted cracking in light water reactors : semiannual report, July 2000 - December 2000.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.; Strain, R. V.; Energy Technology

    2002-04-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from July 2000 to December 2000. Topics that have been investigated include (a) environmental effects on fatigue S-N behavior of primary pressure boundary materials, (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels (SSs), and (c) EAC of Alloys 600 and 690. The fatigue strain-vs.-life data are summarized for the effects of various material, loading, and environmental parameters on the fatigue lives of carbon and low-alloy steels and austenitic SSs. Effects of the reactor coolant environment on the mechanism of fatigue crack initiation are discussed. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented. Slow-strain-rate tensile tests and posttest fractographic analyses were conducted on several model SS alloys irradiated to {approx}0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) in He at 289 C in the Halden reactor. The results were used to determine the influence of alloying and impurity elements on the susceptibility of these steels to IASCC. A fracture toughness J-R curve test was conducted on a commercial heat of Type 304 SS that was irradiated to {approx}2.0 x 10{sup 21} n {center_dot} cm{sup -2} in the Halden reactor. The results were compared with the data obtained earlier on steels irradiated to 0.3 and 0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) (0.45 and 1.35 dpa). Neutron irradiation at 288 C was found to decrease the fracture toughness of austenitic SSs. Tests were conducted on compact-tension specimens of Alloy 600 under cyclic loading to evaluate the enhancement of crack growth rates in LWR environments. Then, the existing fatigue crack growth data on Alloys 600 and 690 were analyzed to establish the effects of temperature, load ratio, frequency, and stress intensity range on crack growth rates in air.

  12. Article for thermal energy storage

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    2000-06-27

    A thermal energy storage composition is provided which is in the form of a gel. The composition includes a phase change material and silica particles, where the phase change material may comprise a linear alkyl hydrocarbon, water/urea, or water. The thermal energy storage composition has a high thermal conductivity, high thermal energy storage, and may be used in a variety of applications such as in thermal shipping containers and gel packs.

  13. Buffer Sizing for Minimum Energy-Delay Product by Using an Approximating Polynomial

    E-Print Network [OSTI]

    Pedram, Massoud

    Buffer Sizing for Minimum Energy-Delay Product by Using an Approximating Polynomial Chang Woo Kang to derive sizing rules for buffered chains, which optimize the overall energy-delay product. Categories result in a poor solution in terms of the energy-delay product. The focus of this work is on multi

  14. On the Energy-Delay Trade-off of a Two-Way Relay Network

    E-Print Network [OSTI]

    Yener, Aylin

    1 On the Energy-Delay Trade-off of a Two-Way Relay Network Xiang He Aylin Yener Wireless relay. The bi-directional nature of the traffic, in this setting, poses a new energy delay trade, queuing, energy-delay trade-off I. INTRODUCTION The two-way relay network considered in this work consists

  15. Wide-Bandwidth, Tunable, Multiple-Pulse-Width Optical Delays Using Slow Light in Cesium Vapor

    E-Print Network [OSTI]

    Boyd, Robert W.

    Wide-Bandwidth, Tunable, Multiple-Pulse-Width Optical Delays Using Slow Light in Cesium Vapor Ryan) We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses to 80 pulse widths by making use of a double absorption reso- nance in cesium. Furthermore, we show

  16. On Secrecy Outage Capacity of Fading Channels Under Relaxed Delay Constraints

    E-Print Network [OSTI]

    Koksal, Can Emre

    On Secrecy Outage Capacity of Fading Channels Under Relaxed Delay Constraints Onur Gungor, Can Emre delay constraints. More specif- ically, we extend the definition of outage secrecy capacity for single, we provide bounds on secrecy outage capacity with k + 1 block delay constraint. We show

  17. Synchronization and Communication with Chaotic Time-Delay Electronic Circuit Systems

    E-Print Network [OSTI]

    Anlage, Steven

    Synchronization and Communication with Chaotic Time-Delay Electronic Circuit Systems David T simulation. Circuit implementation of Mackey- Glass delayed system. #12;)( )(1 )()( tbx tx tax dt tdx n - -+ - = 2.0=a 1.0=b 10=n The Mackey-Glass System The Mackey-Glass mathematical model1: a delay differential

  18. Improved Power-Delay Trade-off in Wireless Ad Hoc Networks Using Opportunistic Routing

    E-Print Network [OSTI]

    Lee, Yong Hoon

    Improved Power-Delay Trade-off in Wireless Ad Hoc Networks Using Opportunistic Routing Won power- delay trade-off than the conventional routing while providing up to a logarithmic boost that the power can be reduced at the expense of increased delay for both scenarios, but better trade-off can

  19. Power and Delay Trade-offs in Fading Channels Randall A. Berry

    E-Print Network [OSTI]

    Berry, Randall

    Power and Delay Trade-offs in Fading Channels by Randall A. Berry S.M., Massachusetts Institute by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arthur C. Smith Chairman, Department Committee on Graduate Students #12;#12;Power and Delay Trade of higher transmission power. The trade-offs between the required power and various notions of delay

  20. Power-Optimal Scheduling for a Green Base Station with Delay Constraints

    E-Print Network [OSTI]

    Sharma, Vinod

    Power-Optimal Scheduling for a Green Base Station with Delay Constraints Anusha Lalitha, Santanu with average delay constraint on the downlink of a Green Base- station. A Green Base-station is powered by both Terms--Power-optimal, Green Base station, Delay con- straint, multi-user. I. INTRODUCTION The main