Sample records for lighting phonons thermal

  1. Manipulation of Thermal Phonons 

    E-Print Network [OSTI]

    Hsu, Chung-Hao

    2013-03-28T23:59:59.000Z

    Developing materials that can conduct electricity easily, but block the motion of phonons is necessary in the applications of thermoelectric devices, which can generate electricity from temperature differences. In converse, a key requirement...

  2. Phonon thermal transport through tilt grain boundaries in strontium titanate

    SciTech Connect (OSTI)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Deng, Bowen; Chernatynskiy, Aleksandr [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-08-21T23:59:59.000Z

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO{sub 3}. Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO{sub 3} contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies.

  3. Acoustic phonon engineering of thermal properties of silicon-based nanostructures

    E-Print Network [OSTI]

    Acoustic phonon engineering of thermal properties of silicon- based nanostructures N D Zincenco1 engineering [2, 7]. The reduction of the thermal conductivity, being a bad news for the thermal management Engineering, University of California ­ Riverside, Riverside, California 92521 USA E-mail: balandin

  4. Thermal Conductivity Spectroscopy Technique to Measure Phonon Mean Free Paths

    E-Print Network [OSTI]

    Schmidt, A. J.

    Size effects in heat conduction, which occur when phonon mean free paths (MFPs) are comparable to characteristic lengths, are being extensively explored in many nanoscale systems for energy applications. Knowledge of MFPs ...

  5. Thermally stimulated 3–15 THz emission at plasmon-phonon frequencies in polar semiconductors

    SciTech Connect (OSTI)

    Požela, J., E-mail: pozela@pfi.lt; Požela, K.; Šil?nas, A.; Širmulis, E.; Kašalynas, I.; Jucien?, V.; Venckevi?ius, R. [Center for Physical Sciences and Technology, Semiconductor Physics Institute (Lithuania)

    2014-12-15T23:59:59.000Z

    The possibilities of distinguishing highly coherent terahertz emission at a specified frequency from the incoherent thermal emission of a hot body are considered. It is experimentally shown that the smooth planar surface (with no diffraction guides) of heated GaAs and AlGaAs wafers emits directed continuous-wave (cw) terahertz radiation at coupled surface plasmon-phonon vibrational frequencies. The recording of terahertz reflectance spectra is demonstrated as a method for the identification of plasmons, optical phonons, and coupled plasmon-phonon vibrations in semiconductors.

  6. Phononic crystal devices

    DOE Patents [OSTI]

    El-Kady, Ihab F. (Albuquerque, NM); Olsson, Roy H. (Albuquerque, NM)

    2012-01-10T23:59:59.000Z

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  7. Thermal Conductivity in Nanoporous Gold Films during Electron-Phonon Nonequilibrium

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

    Hopkins, Patrick E.; Norris, Pamela M.; Phinney, Leslie M.; Policastro, Steven A.; Kelly, Robert G.

    2008-01-01T23:59:59.000Z

    The reduction of nanodevices has given recent attention to nanoporous materials due to their structure and geometry. However, the thermophysical properties of these materials are relatively unknown. In this article, an expression for thermal conductivity of nanoporous structures is derived based on the assumption that the finite size of the ligaments leads to electron-ligament wall scattering. This expression is then used to analyze the thermal conductivity of nanoporous structures in the event of electron-phonon nonequilibrium.

  8. Lighting system with thermal management system

    DOE Patents [OSTI]

    Arik, Mehmet; Weaver, Stanton; Stecher, Thomas; Seeley, Charles; Kuenzler, Glenn; Wolfe, Jr., Charles; Utturkar, Yogen; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2013-05-07T23:59:59.000Z

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  9. Phonon-assisted transient electroluminescence in Si

    SciTech Connect (OSTI)

    Cheng, Tzu-Huan, E-mail: f94943139@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan (China); Chu-Su, Yu [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan and Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan (China); Liu, Chien-Sheng [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, Chii-Wann [Institute of Biomedical Engineering and Institute of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China)

    2014-06-30T23:59:59.000Z

    The phonon-replica infrared emission is observed at room temperature from indirect band gap Si light-emitting diode under forward bias. With increasing injection current density, the broadened electroluminescence spectrum and band gap reduction are observed due to joule heating. The spectral-resolved temporal response of electroluminescence reveals the competitiveness between single (TO) and dual (TO?+?TA) phonon-assisted indirect band gap transitions. As compared to infrared emission with TO phonon-replica, the retarder of radiative recombination at long wavelength region (?1.2??m) indicates lower transition probability of dual phonon-replica before thermal equivalent.

  10. Nonlinear vs. bolometric radiation response and phonon thermal conductance in graphene-superconductor junctions

    SciTech Connect (OSTI)

    Vora, Heli; Nielsen, Bent; Du, Xu [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York (United States)

    2014-02-21T23:59:59.000Z

    Graphene is a promising candidate for building fast and ultra-sensitive bolometric detectors due to its weak electron-phonon coupling and low heat capacity. In order to realize a practical graphene-based bolometer, several important issues, including the nature of radiation response, coupling efficiency to the radiation and the thermal conductance need to be carefully studied. Addressing these issues, we present graphene-superconductor junctions as a viable option to achieve efficient and sensitive bolometers, with the superconductor contacts serving as hot electron barriers. For a graphene-superconductor device with highly transparent interfaces, the resistance readout in the presence of radio frequency radiation is dominated by non-linear response. On the other hand, a graphene-superconductor tunnel device shows dominantly bolometric response to radiation. For graphene devices fabricated on SiO{sub 2} substrates, we confirm recent theoretical predictions of T{sup 2} temperature dependence of phonon thermal conductance in the presence of disorder in the graphene channel at low temperatures.

  11. Effect of phonon confinement on lattice thermal conductivity of lead Telluride quantum well structure

    SciTech Connect (OSTI)

    Tripathi, Madhvendra Nath, E-mail: ommadhav27@gmail.com [Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009, Chhattisgarh (India)

    2014-04-24T23:59:59.000Z

    The paper examines the effect of spatial confinement of acoustic phonons on average group velocity and consequently the lattice thermal conductivity of a free-standing PbTe quantum well structure and their temperature dependence. The average group velocity at 100 Å decreases 30% to the bulk value and falls more rapidly on reducing the width of quantum well. Moreover, the lattice thermal conductivity of 100 Å wide PbTe quantum well with value of 0.60 W/mK shows considerable decrease of 70% compared to it’s bulk value. It is observed that the effect of reduction in well width is less pronounce as temperature increases. This appears mainly due to dominance of umklapp processes over the confinement effects.

  12. Energy resolution and efficiency of phonon-mediated KIDs for light detection

    E-Print Network [OSTI]

    Cardani, L; Cruciani, A; Di Domizio, S; Vignati, M; Bellini, F; Casali, N; Castellano, M G; Coppolecchia, A; Cosmelli, C; Tomei, C

    2015-01-01T23:59:59.000Z

    The development of sensitive cryogenic light detectors is of primary interest for bolometric experiments searching for rare events like Dark Matter interactions or Neutrinoless Double Beta Decay. Thanks to their good energy resolution and the natural multiplexed read-out, Kinetic Inductance Detectors (KIDs) are particularly suitable for this purpose. To efficiently couple KIDs-based light detectors to the large crystals used by the most advanced bolometric detectors, active surfaces of several cm$^2$ are needed. For this reason, we are developing phonon-mediated detectors. In this paper we present the first results obtained with a prototype consisting of four 40 nm thick aluminum resonators patterned on a 2x2 cm$^2$ silicon chip. The detector, exposed to optical pulses and to a $^{57}$Co X-ray source, features an energy resolution of 154+-7 eV and an efficiency of (18+-2)%.

  13. Thermoelectric HVAC and Thermal Comfort Enablers for Light-Duty...

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

    and Thermal Comfort Enablers for Light-Duty Vehicle Applications Thermoelectric HVAC and Thermal Comfort Enablers for Light-Duty Vehicle Applications 2012 DOE Hydrogen and Fuel...

  14. Energy distribution of nonequilibrium electrons and optical phonons in GaAs under band-to-band pumping by intense short pulses of light

    SciTech Connect (OSTI)

    Altybaev, G. S.; Kumekov, S. E., E-mail: skumekov@mail.ru; Mahmudov, A. A. [Satpaev Kazakh National Technical University (Kazakhstan)

    2009-03-15T23:59:59.000Z

    Deviation from the Fermi distribution of nonequilibrium electrons and distribution of 'hot' optical phonons in GaAs under band-to-band pumping by picosecond pulses of light are calculated.

  15. Phonon manipulation with phononic crystals.

    SciTech Connect (OSTI)

    Kim Bongsang; Hopkins, Patrick Edward; Leseman, Zayd C.; Goettler, Drew F.; Su, Mehmet F. (University of New Mexico, Albuquerque, NM); El-Kady, Ihab Fathy; Reinke, Charles M.; Olsson, Roy H., III

    2012-01-01T23:59:59.000Z

    In this work, we demonstrated engineered modification of propagation of thermal phonons, i.e. at THz frequencies, using phononic crystals. This work combined theoretical work at Sandia National Laboratories, the University of New Mexico, the University of Colorado Boulder, and Carnegie Mellon University; the MESA fabrication facilities at Sandia; and the microfabrication facilities at UNM to produce world-leading control of phonon propagation in silicon at frequencies up to 3 THz. These efforts culminated in a dramatic reduction in the thermal conductivity of silicon using phononic crystals by a factor of almost 30 as compared with the bulk value, and about 6 as compared with an unpatterned slab of the same thickness. This work represents a revolutionary advance in the engineering of thermoelectric materials for optimal, high-ZT performance. We have demonstrated the significant reduction of the thermal conductivity of silicon using phononic crystal structuring using MEMS-compatible fabrication techniques and in a planar platform that is amenable to integration with typical microelectronic systems. The measured reduction in thermal conductivity as compared to bulk silicon was about a factor of 20 in the cross-plane direction [26], and a factor of 6 in the in-plane direction. Since the electrical conductivity was only reduced by a corresponding factor of about 3 due to the removal of conductive material (i.e., porosity), and the Seebeck coefficient should remain constant as an intrinsic material property, this corresponds to an effective enhancement in ZT by a factor of 2. Given the number of papers in literature devoted to only a small, incremental change in ZT, the ability to boost the ZT of a material by a factor of 2 simply by reducing thermal conductivity is groundbreaking. The results in this work were obtained using silicon, a material that has benefitted from enormous interest in the microelectronics industry and that has a fairly large thermoelectric power factor. In addition, the techniques and scientific understanding developed in the research can be applied to a wide range of materials, with the caveat that the thermal conductivity of such a material be dominated by phonon, rather than electron, transport. In particular, this includes several thermoelectric materials with attractive properties at elevated temperatures (i.e., greater than room temperature), such as silicon germanium and silicon carbide. It is reasonable that phononic crystal patterning could be used for high-temperature thermoelectric devices using such materials, with applications in energy scavenging via waste-heat recovery and thermoelectric cooling for high-performance microelectronic circuits. The only part of the ZT picture missing in this work was the experimental measurement of the Seebeck coefficient of our phononic crystal devices. While a first-order approximation indicates that the Seebeck coefficient should not change significantly from that of bulk silicon, we were not able to actually verify this assumption within the timeframe of the project. Additionally, with regards to future high-temperature applications of this technology, we plan to measure the thermal conductivity reduction factor of our phononic crystals as elevated temperatures to confirm that it does not diminish, given that the nominal thermal conductivity of most semiconductors, including silicon, decreases with temperature above room temperature. We hope to have the opportunity to address these concerns and further advance the state-of-the-art of thermoelectric materials in future projects.

  16. Thermal-neutron capture in light nuclei

    SciTech Connect (OSTI)

    Raman, S. [Oak Ridge National Lab., TN (United States); Jurney, E.T.; Lynn, J.E. [Los Alamos National Lab., NM (United States)

    1996-10-01T23:59:59.000Z

    We have made considerable progress toward the goal of carrying out thermal-neutron capture {gamma}-ray measurements on all stable isotopes below A=60. Information processed till now has significantly augmented the existing knowledge on the detailed nuclear level structure of many light nuclides. Most of this knowledge comes from our {gamma}-ray energies, level placements, and branching ratios of secondary transitions between low-lying states. Spectroscopic information is also contained in the cross sections of the primary transitions originating from the capturing state. This is deduced from the success of ``direct`` theories of neutron capture for many nuclides, especially those of light and near closed-shell character. 23 refs, 1 tab, 3 figs.

  17. Storage and Retrieval of Thermal Light in Warm Atomic Vapor

    E-Print Network [OSTI]

    Young-Wook Cho; Yoon-Ho Kim

    2010-07-12T23:59:59.000Z

    We report slowed propagation and storage and retrieval of thermal light in warm rubidium vapor using the effect of electromagnetically-induced transparency (EIT). We first demonstrate slowed-propagation of the probe thermal light beam through an EIT medium by measuring the second-order correlation function of the light field using the Hanbury-Brown$-$Twiss interferometer. We also report an experimental study on the effect of the EIT slow-light medium on the temporal coherence of thermal light. Finally, we demonstrate the storage and retrieval of thermal light beam in the EIT medium. The direct measurement of the photon number statistics of the retrieved light field shows that the photon number statistics is preserved during the storage and retrieval process.

  18. Phonon engineering for nanostructures.

    SciTech Connect (OSTI)

    Aubry, Sylvie (Stanford University); Friedmann, Thomas Aquinas; Sullivan, John Patrick; Peebles, Diane Elaine; Hurley, David H. (Idaho National Laboratory); Shinde, Subhash L.; Piekos, Edward Stanley; Emerson, John Allen

    2010-01-01T23:59:59.000Z

    Understanding the physics of phonon transport at small length scales is increasingly important for basic research in nanoelectronics, optoelectronics, nanomechanics, and thermoelectrics. We conducted several studies to develop an understanding of phonon behavior in very small structures. This report describes the modeling, experimental, and fabrication activities used to explore phonon transport across and along material interfaces and through nanopatterned structures. Toward the understanding of phonon transport across interfaces, we computed the Kapitza conductance for {Sigma}29(001) and {Sigma}3(111) interfaces in silicon, fabricated the interfaces in single-crystal silicon substrates, and used picosecond laser pulses to image the thermal waves crossing the interfaces. Toward the understanding of phonon transport along interfaces, we designed and fabricated a unique differential test structure that can measure the proportion of specular to diffuse thermal phonon scattering from silicon surfaces. Phonon-scale simulation of the test ligaments, as well as continuum scale modeling of the complete experiment, confirmed its sensitivity to surface scattering. To further our understanding of phonon transport through nanostructures, we fabricated microscale-patterned structures in diamond thin films.

  19. Thermal resistance and phonon scattering at the interface between carbon nanotube and amorphous polyethylene

    E-Print Network [OSTI]

    Elliott, James

    dynamics study of heat conduction in carbon nanotube (CNT)/polyethylene (PE) composites. Particular thermal conductivity of a macroscopic CNT/PE composite is quantified based on an effective medium approximation model. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Polymer composites are employed

  20. ResearchArticle BuildingThermal,Lighting,

    E-Print Network [OSTI]

    , Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA Abstract Building energy and analyze the thermal performance of buildings, and predict their operational energy consumption. Since@tsinghua.edu.cn A detailed loads comparison of three building energy modeling programs: EnergyPlus, DeST and DOE-2.1E Dandan

  1. Thermal properties of organic light-emitting diodes

    SciTech Connect (OSTI)

    Bergemann, Kevin; Krasny, Robert; Forrest, Stephen R.

    2012-01-01T23:59:59.000Z

    Thermal management is important for the efficient operation of organic light-emitting diodes (OLED, or PHOLED) at high brightness, with the device operating temperature influencing both lifetime and performance. We apply a transmission-matrix approach to analytically model the effects of thermal conduction, convection and radiation on OLED temperature. The model predictions match experiment without requiring the use of fitting parameters. This allows for the simulation of the thermal response of various device architectures, materials combinations and environmental factors under a variety of operating conditions. Using these simulations, we find that 87% of the heat is dissipated through the air space adjacent to the glass package cap. Furthermore, an air gap between the device cathode and cap provides a significant thermal impedance. Minimizing the thickness of the internal air gap can lead to nearly room temperature operation, even at very high brightness.

  2. Manipulation of Thermal Phonons

    E-Print Network [OSTI]

    Hsu, Chung-Hao

    2013-03-28T23:59:59.000Z

    FIGURE Page 1 Schematic thermoelectrics: (a) Seebeck effect. (b) Peltier effect .............. 6 2 Heat transfer through... ................................................................... 37 8 The block diagram of FDTD method calculation ...................................... 38 9 A unit cell with the periodic boundary ....................................................... 49 10 Lattice positions and primitive lattice...

  3. Genetic algorithms used for the optimization of light-emitting diodes and solar thermal collectors

    E-Print Network [OSTI]

    Mayer, Alexandre

    Genetic algorithms used for the optimization of light-emitting diodes and solar thermal collectors developed for the optimization of light-emitting diodes (LED) and solar thermal collectors. The surface a light-extraction efficiency of only 3.7%). The solar thermal collector we considered consists

  4. Lighting system with thermal management system having point contact synthetic jets

    DOE Patents [OSTI]

    Arik, Mehmet; Weaver, Stanton Earl; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Sharma, Rajdeep

    2013-12-10T23:59:59.000Z

    Lighting system having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system includes a plurality of synthetic jets. The synthetic jets are arranged within the lighting system such that they are secured at contact points.

  5. 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

  6. Thermal and lighting performance of toplighting systems in the hot and humid climate of Thailand

    E-Print Network [OSTI]

    Harntaweewongsa, Siritip

    2006-10-30T23:59:59.000Z

    , light distribution, and uniformity. EnergyPlus was used as the thermal analysis tool, and RADIANCE, along with a physical scale model, was used as the lighting performance analysis tool. The sky conditions tested were overcast, clear sky...

  7. Nonequilibrium phonon effects in midinfrared quantum cascade lasers

    SciTech Connect (OSTI)

    Shi, Y. B., E-mail: yshi9@wisc.edu; Knezevic, I., E-mail: knezevic@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691 (United States)

    2014-09-28T23:59:59.000Z

    We investigate the effects of nonequilibrium phonon dynamics on the operation of a GaAs-based midinfrared quantum cascade laser over a range of temperatures (77–300?K) via a coupled ensemble Monte Carlo simulation of electron and optical-phonon systems. Nonequilibrium phonon effects are shown to be important below 200?K. At low temperatures, nonequilibrium phonons enhance injection selectivity and efficiency by drastically increasing the rate of interstage electron scattering from the lowest injector state to the next-stage upper lasing level via optical-phonon absorption. As a result, the current density and modal gain at a given field are higher and the threshold current density lower and considerably closer to experiment than results obtained with thermal phonons. By amplifying phonon absorption, nonequilibrium phonons also hinder electron energy relaxation and lead to elevated electronic temperatures.

  8. Detecting phonon blockade with photons

    SciTech Connect (OSTI)

    Didier, Nicolas; Pugnetti, Stefano; Fazio, Rosario [NEST, Scuola Normale Superiore and Istituto di Nanoscienze - CNR, Pisa (Italy); Blanter, Yaroslav M. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

    2011-08-01T23:59:59.000Z

    Measuring the quantum dynamics of a mechanical system, when few phonons are involved, remains a challenge. We show that a superconducting microwave resonator linearly coupled to the mechanical mode constitutes a very powerful probe for this scope. This new coupling can be much stronger than the usual radiation pressure interaction by adjusting a gate voltage. We focus on the detection of phonon blockade, showing that it can be observed by measuring the statistics of the light in the cavity. The underlying reason is the formation of an entangled state between the two resonators. Our scheme realizes a phonotonic Josephson junction, giving rise to coherent oscillations between phonons and photons as well as a self-trapping regime for a coupling smaller than a critical value. The transition from the self-trapping to the oscillating regime is also induced dynamically by dissipation.

  9. Strong enhancement of light absorption and highly directive thermal emission in graphene

    E-Print Network [OSTI]

    Chen, Po

    Strong enhancement of light absorption and highly directive thermal emission in graphene Mingbo Pu: Graphene is a two-dimensional material with exotic electronic, optical and thermal properties. The optical absorption in monolayer graphene is limited by the fine structure constant . Here we demonstrated the strong

  10. Theory of Light Emission in Sonoluminescence as Thermal Radiation

    E-Print Network [OSTI]

    Wang-Kong Tse; P. T. Leung

    2006-06-14T23:59:59.000Z

    Based on the model proposed by Hilgenfeldt {\\it at al.} [Nature {\\bf 398}, 401 (1999)], we present here a comprehensive theory of thermal radiation in single-bubble sonoluminescence (SBSL). We first invoke the generalized Kirchhoff's law to obtain the thermal emissivity from the absorption cross-section of a multilayered sphere (MLS). A sonoluminescing bubble, whose internal structure is determined from hydrodynamic simulations, is then modelled as a MLS and in turn the thermal radiation is evaluated. Numerical results obtained from simulations for argon bubbles show that our theory successfully captures the major features observed in SBSL experiments.

  11. ccsd-00021119,version1-17Mar2006 Light transport in cold atoms and thermal decoherence

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ccsd-00021119,version1-17Mar2006 Light transport in cold atoms and thermal decoherence G. Labeyrie, we investigate experimentally and the- oretically how coherent transport of light inside a cold motivated by astrophysical purposes, wave transport in opaque media was first analyzed through a detailed

  12. Light Transport in Cold Atoms and Thermal Decoherence G. Labeyrie,1,* D. Delande,2

    E-Print Network [OSTI]

    Light Transport in Cold Atoms and Thermal Decoherence G. Labeyrie,1,* D. Delande,2 R. Kaiser,1 experimentally and theoretically how coherent transport of light inside a cold atomic vapor is affected motivated by astrophysical purposes, wave transport in opaque media was first analyzed by means

  13. Light transport in cold atoms and thermal decoherence G. Labeyrie,1,

    E-Print Network [OSTI]

    Delande, Dominique

    Light transport in cold atoms and thermal decoherence G. Labeyrie,1, D. Delande,2 R. Kaiser,1 and theoreti- cally how coherent transport of light inside a cold atomic vapour is affected by the residual, wave transport in opaque media was first analyzed by means of a detailed balance of energy transfers

  14. Waverly Light and Power- Residential Solar Thermal Rebates

    Broader source: Energy.gov [DOE]

    Waverly Light and Power (WL&P) offers rebates for solar hot water heating systems to its residential customers. All purchases must be pre-approved through WL&P's solar water heater...

  15. Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects

    SciTech Connect (OSTI)

    Navarro-Urrios, D., E-mail: daniel.navarrourrios@nano.cnr.it [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); NEST, Istituto Nanoscienze–CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa I-56127 (Italy); Gomis-Bresco, J.; Alzina, F. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); Capuj, N. E. [Depto. Física, Universidad de la Laguna, 38206 La Laguna (Spain); Griol, A.; Puerto, D.; Martínez, A. [Nanophotonics Technology Center, Universitat Politècnica de València, Valencia (Spain); Sotomayor-Torres, C. M. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); Catalan Institution for Research and Advanced Studies (ICREA), 08010 Barcelona (Spain)

    2014-09-07T23:59:59.000Z

    We report on the modification of the optical and mechanical properties of a silicon 1D optomechanical crystal cavity due to thermo-optic effects in a high phonon/photon population regime. The cavity heats up due to light absorption in a way that shifts the optical modes towards longer wavelengths and the mechanical modes to lower frequencies. By combining the experimental optical results with finite-difference time-domain simulations, we establish a direct relation between the observed wavelength drift and the actual effective temperature increase of the cavity. By assuming that the Young's modulus decreases accordingly to the temperature increase, we find a good agreement between the mechanical mode drift predicted using a finite element method and the experimental one.

  16. Thermal And Mechanical Analysis of High-power Light-emitting Diodes with Ceramic Packages

    E-Print Network [OSTI]

    J. Hu; L. Yang; M. -W. Shin

    2008-01-07T23:59:59.000Z

    In this paper we present the thermal and mechanical analysis of high-power light-emitting diodes (LEDs) with ceramic packages. Transient thermal measurements and thermo-mechanical simulation were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistance from the junction to the ambient was decreased from 76.1 oC/W to 45.3 oC/W by replacing plastic mould to ceramic mould for LED packages. Higher level of thermo-mechanical stresses in the chip were found for LEDs with ceramic packages despite of less mismatching coefficients of thermal expansion comparing with plastic packages. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high power LEDs with ceramic packages is critically important and should be in charge of delaminating interface layers in the packages.

  17. Phonon interference effects in molecular junctions

    SciTech Connect (OSTI)

    Markussen, Troels, E-mail: troels.markussen@gmail.com [Center for Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)] [Center for Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2013-12-28T23:59:59.000Z

    We study coherent phonon transport through organic, ?-conjugated molecules. Using first principles calculations and Green's function methods, we find that the phonon transmission function in cross-conjugated molecules, like meta-connected benzene, exhibits destructive quantum interference features very analogous to those observed theoretically and experimentally for electron transport in similar molecules. The destructive interference features observed in four different cross-conjugated molecules significantly reduce the thermal conductance with respect to linear conjugated analogues. Such control of the thermal conductance by chemical modifications could be important for thermoelectric applications of molecular junctions.

  18. Light transport in cold atoms and thermal decoherence

    E-Print Network [OSTI]

    Guillaume Labeyrie; Dominique Delande; Robin Kaiser; Christian Miniatura

    2006-03-17T23:59:59.000Z

    By using the coherent backscattering interference effect, we investigate experimentally and theoretically how coherent transport of light inside a cold atomic vapour is affected by the residual motion of atomic scatterers. As the temperature of the atomic cloud increases, the interference contrast dramatically decreases emphazising the role of motion-induced decoherence for resonant scatterers even in the sub-Doppler regime of temperature. We derive analytical expressions for the corresponding coherence time.

  19. Thermal light cannot be represented as a statistical mixture of pulses

    E-Print Network [OSTI]

    Aurélia Chenu; Agata M. Bra?czyk; Gregory D. Scholes; J. E. Sipe

    2014-11-28T23:59:59.000Z

    We ask whether or not thermal light can be represented as a mixture of single broadband coherent pulses. We find that it cannot. Such a mixture of pulses is simply not rich enough to mimic thermal light; indeed, it cannot even reproduce the first-order correlation function. We show that it is possible to construct a modified mixture of single coherent pulses that does yield the correct first-order correlation function at equal space points. However, as we then demonstrate, such a mixture cannot reproduce the second-order correlation function.

  20. Synthetic thermoelectric materials comprising phononic crystals

    DOE Patents [OSTI]

    El-Kady, Ihab F; Olsson, Roy H; Hopkins, Patrick; Reinke, Charles; Kim, Bongsang

    2013-08-13T23:59:59.000Z

    Synthetic thermoelectric materials comprising phononic crystals can simultaneously have a large Seebeck coefficient, high electrical conductivity, and low thermal conductivity. Such synthetic thermoelectric materials can enable improved thermoelectric devices, such as thermoelectric generators and coolers, with improved performance. Such synthetic thermoelectric materials and devices can be fabricated using techniques that are compatible with standard microelectronics.

  1. PHONONS IN INTRINSIC JOSEPHSON SYSTEMS

    SciTech Connect (OSTI)

    C. PREIS; K. SCHMALZL; ET AL

    2000-10-01T23:59:59.000Z

    Subgap structures in the I-V curves of layered superconductors are explained by the excitation of phonons by Josephson oscillations. In the presence of a magnetic field applied parallel to the layers additional structures due to fluxon motion appear. Their coupling with phonons is investigated theoretically and a shift of the phonon resonances in strong magnetic fields is predicted.

  2. Thermal performance of typical light frame walls with reflective surface insulations

    SciTech Connect (OSTI)

    Miller, R.G. (Jim Walter Research Corp., St. Petersburg, FL (US)); Riskowski, G.L.; Christianson, L.L. (Agricultural Engineering Dept., Univ. of Illinois at Urbana-Champaign, IL (US))

    1989-01-01T23:59:59.000Z

    A series of tests were conducted in a guarded hotbox to evaluate the thermal performance (R-value) of wall constructions typical of light-frame buildings that are commonly used in agricultural applications. The systems were insulated with either a commercially available foil-faced bubble pack material (FFBP) or foil-faced polyisocyanurate (PIR) foam board. Tests were conducted under two different temperature conditions, chosen to be representative of a midwestern winter and summer. This paper reports temperatures of the surfaces bounding the reflective airspaces measured and the R-value calculated. These data were used in the ASHRAE series/parallel calculations and the resultant R-value was compared to the measured R-value. Agreement was usually better than 10%.

  3. Hanbury Brown-Twiss effect and thermal light ghost imaging: A unified approach

    E-Print Network [OSTI]

    Wang, Li-Gang; Qamar, Sajid; Zhu, Shi-Yao; Zubairy, M. Suhail

    2009-01-01T23:59:59.000Z

    is detected by D1 and D2 in both the experiments. For the thermal light, the field statistics is Gaussian and this allows the calculation of the second-order correlation from the first-order correlation, i.e., G2#1;u 1,u2#2; = #5;I1I2#6; = #5;I#1;u 1...#2;#6;#5;I#1;u2#2;#6; + #7;#2;#1;u 1,u2#2;#7;2, #1;1#2; where #5;I#1;u 1,2#2;#6; are the intensities at the points u 1 and u2 on the planes of D1 and D2, and #2;#1;u 1 ,u2#2;= #5;E+#1;u 1#2;E#1;u2#2;#6; is the cross correlation. The correlations...

  4. Effects of temperature and pressure on phonons in FeSi1–xAlx

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

    Delaire, O.; Al-Qasir, I. I.; Ma, J.; dos Santos, A. M.; Sales, B. C.; Mauger, L.; Stone, M. B.; Abernathy, D. L.; Xiao, Y.; Somayazulu, M.

    2013-05-01T23:59:59.000Z

    The effects of temperature and pressure on phonons in B20 compounds FeSi1–xAlx were measured using inelastic neutron scattering and nuclear-resonant inelastic x-ray scattering. The effect of hole doping through Al substitution is compared to results of alloying with Co (electron doping) in Fe??xCoxSi. While the temperature dependence of phonons in FeSi is highly anomalous, doping with either type of carriers leads to a recovery of the normal quasiharmonic behavior. Density functional theory (DFT) computations of the electronic band structure and phonons were performed. The anomaly in the temperature dependence of the phonons in undoped FeSi was related to the narrow band gap, and its sensitivity to the effect of thermal disordering by phonons. On the other hand, the pressure dependence of phonons at room temperature in undoped FeSi follows the quasiharmonic behavior and is well reproduced by the DFT calculations.

  5. Mineralogy of the light-toned outcrop at Meridiani Planum as seen by the Miniature Thermal Emission Spectrometer and implications

    E-Print Network [OSTI]

    Glotch, Timothy D.

    Mineralogy of the light-toned outcrop at Meridiani Planum as seen by the Miniature Thermal Emission a spectral library used to determine the mineralogy of the outcrop from this spectral shape. Linear mineralogy to chemistry shows good agreement with the chemical composition of the outcrops determined by APXS

  6. Junction Temperature Measurements and Thermal Modeling of GaInN/GaN Quantum Well Light-Emitting Diodes

    E-Print Network [OSTI]

    Wetzel, Christian M.

    quantum well (QW) light-emitting diodes (LEDs) grown on sapphire and bulk GaN substrate by micro efficiency in dies grown on GaN substrates with a thermal resistance of 75 K/W. For dies on sapphire of GaN-based blue and green LEDs grown on sapphire and GaN substrates using micro-Raman spectroscopy

  7. Microscopic mechanism of low thermal conductivity in lead telluride

    SciTech Connect (OSTI)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL

    2012-01-01T23:59:59.000Z

    Themicroscopic physics behind low-lattice thermal conductivity of single-crystal rock salt lead telluride (PbTe) is investigated. Mode-dependent phonon (normal and umklapp) scattering rates and their impact on thermal conductivity were quantified by first-principles-based anharmonic lattice dynamics calculations that accurately reproduce thermal conductivity in a wide temperature range. The low thermal conductivity of PbTe is attributed to the scattering of longitudinal acoustic phonons by transverse optical phonons with large anharmonicity and small group velocity of the soft transverse acoustic phonons. This results in enhancing the relative contribution of optical phonons, which are usually minor heat carriers in bulk materials.

  8. Calculation of Confined Phonon Spectrum in Narrow Silicon Nanowires using the Valence Force Field Method

    E-Print Network [OSTI]

    > channel is thus the most suitable orientation for thermoelectric devices based on Si nanowires since- based devices for thermoelectric and thermal management applications. Index terms: Confined phonons attracted significant attention as efficient thermoelectric (TE) materials after it was demonstrated

  9. Phonon dispersion in graphene

    E-Print Network [OSTI]

    L. A. Falkovsky

    2007-08-11T23:59:59.000Z

    Taking into account the constraints imposed by the lattice symmetry, the phonon dispersion is calculated for graphene with interactions between the first and second nearest neighbors in the framework of the Born-von Karman model. Analytical expressions are obtained for the out-of-plane (bending) modes determined only by two force constants as well as for the in-plane modes with four force constants. Values of the force constants are found in fitting to elastic constants and Raman frequencies observed in graphite.

  10. Thermal conductivity of bulk nanostructured lead telluride

    SciTech Connect (OSTI)

    Hori, Takuma [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Chen, Gang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Shiomi, Junichiro, E-mail: shiomi@photon.t.u-tokyo.ac.jp [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    2014-01-13T23:59:59.000Z

    Thermal conductivity of lead telluride with embedded nanoinclusions was studied using Monte Carlo simulations with intrinsic phonon transport properties obtained from first-principles-based lattice dynamics. The nanoinclusion/matrix interfaces were set to completely reflect phonons to model the maximum interface-phonon-scattering scenario. The simulations with the geometrical cross section and volume fraction of the nanoinclusions matched to those of the experiment show that the experiment has already reached the theoretical limit of thermal conductivity. The frequency-dependent analysis further identifies that the thermal conductivity reduction is dominantly attributed to scattering of low frequency phonons and demonstrates mutual adaptability of nanostructuring and local disordering.

  11. Thermal conductivity of the quark matter for the SU(2) light-flavor sector

    E-Print Network [OSTI]

    Seung-il Nam

    2015-03-04T23:59:59.000Z

    We investigate the thermal conductivity ($\\kappa$) of the quark matter at finite quark chemical potential $(\\mu)$ and temperature $(T)$, employing the Green-Kubo formula, for the SU(2) light-flavor sector with the finite current-quark mass $m=5$ MeV. As a theoretical framework, we construct an effective thermodynamic potential from the $(\\mu,T)$-modified liquid-instanton model (mLIM). Note that all the relevant model parameters are designated as functions of $T$, using the trivial-holonomy caloron solution. By solving the self-consistent equation of mLIM, we acquire the constituent-quark mass $M_0$ as a function of $T$ and $\\mu$, satisfying the universal-class patterns of the chiral phase transition. From the numerical results for $\\kappa$, we observe that there emerges a peak at $\\mu\\approx200$ MeV for the low-$T$ region, i.e. $T\\lesssim100$ MeV. As $T$ increase over $T\\approx100$ MeV, the curve for $\\kappa$ is almost saturated as a function of $T$ in the order of $\\sim10^{-1}\\,\\mathrm{GeV}^2$, and grows with respect to $\\mu$ smoothly. At the normal nuclear-matter density $\\rho_0=0.17\\,\\mathrm{fm}^{-3}$, $\\kappa$ shows its maximum $6.22\\,\\mathrm{GeV}^2$ at $T\\approx10$ MeV, then decreases exponentially down to $\\kappa\\approx0.2\\,\\mathrm{GeV}^2$. We also compute the ratio of $\\kappa$ and the entropy density, i.e. $\\kappa/s$ as a function of $(\\mu,T)$ which is a monotonically decreasing function for a wide range of $T$, then approaches a lower bound at very high $T$: $\\kappa/s_\\mathrm{min}\\gtrsim0.3\\,\\mathrm{GeV}^{-1}$ in the vicinity of $\\mu=0$.

  12. Structure of crystalline oxide ceramics studied by phonon spectroscopy

    SciTech Connect (OSTI)

    Kaminskii, Alexandr A; Taranov, A V; Khazanov, E N

    2013-03-31T23:59:59.000Z

    This paper describes a method for gaining detailed insight into the structure and phonon spectrum of polycrystalline oxide ceramics. We examine how the diffusion coefficient of subterahertz phonons is related to the properties of a system of grain boundaries and to the grain size and structure and demonstrate that the temperature dependence of the phonon diffusion coefficient at liquid-helium temperatures is determined by the spectral properties of the intergranular layer, which allows one to estimate the volumeaveraged intergranular layer thickness and acoustic impedance. We also analyse the effect of plastic deformation via twinning on the formation of the structure of grains and intergranular layers, which determine the thermophysical, acoustic and optical properties of ceramic materials. (extreme light fields and their applications)

  13. Thermal Issues Associated with the Lighting Systems, Electronics Racks, and Pre-Amplifier Modules in the National Ignition System

    SciTech Connect (OSTI)

    A. C. Owen; J. D. Bernardin; K. L. Lam

    1998-08-01T23:59:59.000Z

    This report summarizes an investigation of the thermal issues related to the National Ignition Facility. The influence of heat sources such as lighting fixtures, electronics racks, and pre-amplifier modules (PAMs) on the operational performance of the laser guide beam tubes and optical alignment hardware in the NE laser bays were investigated with experiments and numerical models. In particular, empirical heat transfer data was used to establish representative and meaningful boundary conditions and also serve as bench marks for computational fluid dynamics (CFD) models. Numerical models, constructed with a commercial CFD code, were developed to investigate the extent of thermal plumes and radiation heat transfer from the heat sources. From these studies, several design modifications were recommended including reducing the size of all fluorescent lights in the NIF laser bays to single 32 W bulb fixtures, maintaining minimum separation distances between light fixtures/electronics racks and beam transport hardware, adding motion sensors in areas of the laser bay to control light fixture operation during maintenance procedures, properly cooling all electronics racks with air-water heat exchangers with heat losses greater than 25 W/rack to the M1 laser bay, ensuring that the electronics racks are not overcooked and thus maintain their surface temperatures to within a few degrees centigrade of the mean air temperature, and insulating the electronic bays and optical support structures on the PAMs.

  14. Phonons with orbital angular momentum

    SciTech Connect (OSTI)

    Ayub, M. K. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2011-10-15T23:59:59.000Z

    Ion accoustic waves or phonon modes are studied with orbital angular momentum (OAM) in an unmagnetized collissionless uniform plasma, whose constituents are the Boltzmann electrons and inertial ions. For this purpose, we have employed the fluid equations to obtain a paraxial equation in terms of ion density perturbations and discussed its Gaussian beam and Laguerre-Gauss (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is presented, allowing to express the components of the electric field in terms of LG potential perturbations. The energy flux due to phonons is also calculated and the corresponding OAM is derived. Numerically, it is shown that the parameters such as azimuthal angle, radial and angular mode numbers, and beam waist, strongly modify the profiles of the phonon LG potential. The present results should be helpful in understanding the phonon mode excitations produced by Brillouin backscattering of laser beams in a uniform plasma.

  15. Microsecond switchable thermal antenna

    SciTech Connect (OSTI)

    Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr; Benisty, Henri; Besbes, Mondher [Laboratoire Charles Fabry, UMR 8501, Institut d'Optique, CNRS, Université Paris-Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France)

    2014-07-21T23:59:59.000Z

    We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO{sub 2}). This thermal source is made of a periodically patterned tunable VO{sub 2} nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO{sub 2} phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heating less, the VO{sub 2} layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.

  16. Characterization of a new acne vulgaris treatment device combining light and thermal treatment methods

    E-Print Network [OSTI]

    Chen, Zhongping

    on the tip and 39.7 1C in the porcine skin samples. The peak intensity of the light-emitting diode (LED

  17. An informatics based analysis of the impact of isotope substitution on phonon modes in graphene

    SciTech Connect (OSTI)

    Broderick, Scott; Srinivasan, Srikant; Rajan, Krishna [Department of Material Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States); Ray, Upamanyu; Balasubramanian, Ganesh, E-mail: bganesh@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-06-16T23:59:59.000Z

    It is shown by informatics that the high frequency short ranged modes exert a significant influence in impeding thermal transport through isotope substituted graphene nanoribbons. Using eigenvalue decomposition methods, we have extracted features in the phonon density of states spectra that reveal correlations between isotope substitution and phonon modes. This study also provides a data driven computational framework for the linking of materials chemistry and transport properties in 2D systems.

  18. Demand Shifting with Thermal Mass in Light and Heavy Mass Commercial Buildings

    E-Print Network [OSTI]

    Xu, Peng

    2010-01-01T23:59:59.000Z

    as a Demand Response (DR) strategy for commercial buildings.demand response program because the added demand reduction from different buildingsdemand response, thermal mass INTRODUCTION The structural mass within existing commercial buildings

  19. Light stable isotope study of the Roosevelt Hot Springs thermal area, Southwestern Utah

    SciTech Connect (OSTI)

    Rohrs D.T.; Bowman, J.R.

    1980-05-01T23:59:59.000Z

    The isotopic composition of hydrogen, oxygen, and carbon has been determined for regional cold springs, thermal fluids, and rocks and minerals from the Roosevelt Hot Springs thermal area. The geothermal system has developed within plutonic granitic rocks and amphibolite facies gneiss, relying upon fracture-controlled permeability for the migration of the thermal fluids. Probably originating as meteoric waters in the upper elevations of the Mineral Mountains, the thermal waters sampled in the production wells display an oxygen isotopic shift of at least +1.2. Depletions of delta /sup 18/O in wole rock, K-feldspar, and biotite have a positive correlation with alteration intensity. W/R mass ratios, calculated from the isotopic shifts of rock and water, range up to 3.0 in a producing horizon of one well, although the K-feldspar has experienced only 30% exchange with the thermal waters. While veinlet quartz has equilibrated with the thermal waters, the /sup 18/O values of K-mica clay, an alteration product of plagioclase, mimic the isotopic composition of K-feldspar and whole rock. This suggests that locally small W/R ratios enable plagioclase to influence its alteration products by isotopic exchange.

  20. Neutron Scattering Investigation of Phonon Scattering Rates in Ag1-xSb1+xTe2+x (x = 0, 0.1, and 0.2)

    SciTech Connect (OSTI)

    Abernathy, Douglas L [ORNL; Budai, John D [ORNL; Delaire, Olivier A [ORNL; Ehlers, Georg [ORNL; Hong, Tao [ORNL; Karapetrova, Evguenia A. [Argonne National Laboratory (ANL); Ma, Jie [ORNL; May, Andrew F [ORNL; McGuire, Michael A [ORNL; Specht, Eliot D [ORNL

    2014-01-01T23:59:59.000Z

    The phonon dispersions and scattering rates of the thermoelectric material AgSbTe$_{2}$ were measured as a function of temperature with inelastic neutron scattering. The results show that phonon scattering rates are large and weakly dependent on temperature. The lattice thermal conductivity was calculated from the measured phonon lifetimes and group velocities, providing good agreement with bulk transport measurements. The measured phonon scattering rates and their temperature dependence are compared with models of phonon scattering by anharmonicity and point defect. We find that these processes cannot account for the large total phonon scattering rates observed, and their lack of temperature dependence. Neutron and synchrotron diffraction measurements on single crystals revealed an extensive nanostructure from cation ordering, which is likely responsible for the strong phonon scattering.

  1. Unconventional plasmon-phonon coupling in graphene

    E-Print Network [OSTI]

    Jablan, Marinko

    We predict the existence of coupled plasmon-phonon excitations in graphene by using the self-consistent linear response formalism. The unique electron-phonon interaction in graphene leads to unconventional mixing of plasmon ...

  2. Phonon-mediated coupling between quantum dots through an off-resonant microcavity

    E-Print Network [OSTI]

    Arka Majumdar; Michal Bajcsy; Armand Rundquist; Erik Kim; Jelena Vuckovic

    2011-11-30T23:59:59.000Z

    We present experimental results showing phonon-mediated coupling between two quantum dots embedded inside a photonic crystal microcavity. With only one of the dots being spectrally close to the cavity, we observe both frequency up-conversion and down-conversion of the pump light via a $\\sim1.2$ THz phonon. We demonstrate this process for both weak and strong regimes of dot-cavity coupling, and provide a simple theoretical model explaining our observations.

  3. Multiscale thermal transport.

    SciTech Connect (OSTI)

    Graham, Samuel Jr. (; .); Wong, C. C.; Piekos, Edward Stanley

    2004-02-01T23:59:59.000Z

    A concurrent computational and experimental investigation of thermal transport is performed with the goal of improving understanding of, and predictive capability for, thermal transport in microdevices. The computational component involves Monte Carlo simulation of phonon transport. In these simulations, all acoustic modes are included and their properties are drawn from a realistic dispersion relation. Phonon-phonon and phonon-boundary scattering events are treated independently. A new set of phonon-phonon scattering coefficients are proposed that reflect the elimination of assumptions present in earlier analytical work from the simulation. The experimental component involves steady-state measurement of thermal conductivity on silicon films as thin as 340nm at a range of temperatures. Agreement between the experiment and simulation on single-crystal silicon thin films is excellent, Agreement for polycrystalline films is promising, but significant work remains to be done before predictions can be made confidently. Knowledge gained from these efforts was used to construct improved semiclassical models with the goal of representing microscale effects in existing macroscale codes in a computationally efficient manner.

  4. The USDOE Forrestal Lighting Retrofit: Analysis of Electricity and Thermal Savings

    E-Print Network [OSTI]

    Haberl, J. S.; Bou-Saada, T. E.

    1995-01-01T23:59:59.000Z

    ,705 or 76% of the total monetary savings. The measured energy savings performed within 90% of the estimated savings. Quite surprisingly, the thermal savings which were not included in initial estimates by the USDOE accounted for $102,824 or 24...

  5. Structural, thermal, optical properties and simulation of white light of titanium-tungstate-tellurite glasses doped with dysprosium

    SciTech Connect (OSTI)

    Jyothi, L. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Upender, G. [Glass Science and Technology Section, Glass Division, CSIR-CGCRI, Kolkata 700032 (India); Kuladeep, R. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Rao, D. Narayana, E-mail: dnrsp@uohyd.ernet.in [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2014-02-01T23:59:59.000Z

    Graphical abstract: CIE coordinate diagram of different concentrations of the Dy{sup 3+}-doped TTWD glasses with coordinates in the white light region. - Highlights: • Radiative lifetime of {sup 4}F{sub 9/2} level of Dy{sup 3+} ions is longer in the tellurite glass. • Quantum efficiency is found to be high. • These glasses are suitable materials for generating white light. - Abstract: Structural, thermal, optical properties and simulation of white light of Dy{sup 3+}-doped tellurite glasses of composition TTWD: (75 ? x)TeO{sub 2} ? 10TiO{sub 2} ? 15WO{sub 3} ? xDy{sub 2}O{sub 3} (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were investigated. Raman spectra revealed that the glass contains TeO{sub 4}, TeO{sub 3}, WO{sub 4} and WO{sub 6} units. Differential scanning calorimetry (DSC) measurements were carried out to measure the glass transition temperature of all the glasses. From the optical absorption spectra, luminescence spectra and using the Judd–Ofelt (JO) analysis, we estimated the radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes. The decay curves at lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (?0.5 mol%) due to energy transfer processes. The effective lifetime for the {sup 4}F{sub 9/2} level decreases with increase in Dy{sub 2}O{sub 3} concentration for the glasses under investigation. The non-exponential decay curves could fit well to the Inokuti–Hirayama (IH) model with S = 6, indicating that the nature of interaction responsible for energy transfer is of dipole–dipole type. Simulation of white light is examined with varying concentration and the results indicate that these glasses are suitable for white light emitting diode applications.

  6. Full-dispersion Monte Carlo simulation of phonon transport in micron-sized graphene nanoribbons

    SciTech Connect (OSTI)

    Mei, S., E-mail: smei4@wisc.edu; Knezevic, I., E-mail: knezevic@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Maurer, L. N. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Aksamija, Z. [Department of Electrical and Computer Engineering, University of Massachusetts-Amherst, Amherst, Massachusetts 01003 (United States)

    2014-10-28T23:59:59.000Z

    We simulate phonon transport in suspended graphene nanoribbons (GNRs) with real-space edges and experimentally relevant widths and lengths (from submicron to hundreds of microns). The full-dispersion phonon Monte Carlo simulation technique, which we describe in detail, involves a stochastic solution to the phonon Boltzmann transport equation with the relevant scattering mechanisms (edge, three-phonon, isotope, and grain boundary scattering) while accounting for the dispersion of all three acoustic phonon branches, calculated from the fourth-nearest-neighbor dynamical matrix. We accurately reproduce the results of several experimental measurements on pure and isotopically modified samples [S. Chen et al., ACS Nano 5, 321 (2011);S. Chen et al., Nature Mater. 11, 203 (2012); X. Xu et al., Nat. Commun. 5, 3689 (2014)]. We capture the ballistic-to-diffusive crossover in wide GNRs: room-temperature thermal conductivity increases with increasing length up to roughly 100??m, where it saturates at a value of 5800?W/m K. This finding indicates that most experiments are carried out in the quasiballistic rather than the diffusive regime, and we calculate the diffusive upper-limit thermal conductivities up to 600?K. Furthermore, we demonstrate that calculations with isotropic dispersions overestimate the GNR thermal conductivity. Zigzag GNRs have higher thermal conductivity than same-size armchair GNRs, in agreement with atomistic calculations.

  7. Nanoscale transport of phonons: Dimensionality, subdiffusion, molecular damping, and interference effects

    SciTech Connect (OSTI)

    Walczak, Kamil; Yerkes, Kirk L. [Aerospace Systems Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States)

    2014-05-07T23:59:59.000Z

    We examine heat transport carried by acoustic phonons in the systems composed of nanoscale chains of masses coupled to two thermal baths of different temperatures. Thermal conductance is obtained by using linearized Landauer-type formula for heat flux with phonon transmission probability calculated within atomistic Green's functions (AGF) method. AGF formalism is extended onto dissipative chains of masses with harmonic coupling beyond nearest-neighbor approximation, while atomistic description of heat reservoirs is also included into computational scheme. In particular, the phonon lifetimes and the phonon frequency shifts are discussed for harmonic lattices of different dimensions. Further, resonant structure of phonon transmission spectrum is analyzed with respect to reservoir-induced effects, molecular damping, and mass-to-mass harmonic coupling. Analysis of transmission zeros (antiresonances) and their accompanied Fano-shape resonances are discussed as a result of interference effects between different vibrational modes. Finally, we also predict subdiffusive transport regime for low-frequency ballistic phonons propagated along a linear chain of harmonically coupled masses.

  8. Interface modified thermally stable hole transporting layer for efficient organic light emitting diodes

    SciTech Connect (OSTI)

    Grover, Rakhi, E-mail: grover.rakhi@gmail.com [Amity Institute of Advanced Research and Studies (Materials and Devices), Amity University, Noida, Uttar Pradesh 201303 (India); Srivastava, Ritu, E-mail: ritu@mail.nplindia.org; Dagar, Janardan; Kamalasanan, M. N. [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, CSIR-Network of Institute for Solar Energy (NISE), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Mehta, D. S. [Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

    2014-08-14T23:59:59.000Z

    Electrical transport in thermally stable 2, 7-bis [N, N-bis (4-methoxy-phenyl) amino]-9, 9-spirobifluorene (MeO-Spiro-TPD) thin films has been investigated as a function of temperature and organic layer thickness. ITO/MeO-Spiro-TPD interface was found to be injection limited and has been studied in detail to find barrier height for hole injection. The thickness of tetra-fluoro-tetracyano-quinodimethane thin films were optimized to be used as hole injection buffer layer which resulted in switching of charge transport mechanism from injection limited to space charge limited conduction above a critical thickness of 3?nm. Hole mobility has been measured using transient space charge limited conduction (SCLC), field dependent SCLC, and top contact transistor characteristics. The charge carrier transport in interface modified hole only devices was analysed using Gaussian disorder model. The thermal stability of MeO-Spiro-TPD has been investigated by atomic force microscopy and X-ray diffraction studies. The study indicates a thermally stable and highly efficient hole transport material for application in organic semiconductor based devices.

  9. Lighting

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9 5Let us countLighting Sign In About | Careers |

  10. Ultrafast and steady-state laser heating effects on electron relaxation and phonon coupling mechanisms in thin gold films

    SciTech Connect (OSTI)

    Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Duda, John C. [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States) [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Seagate Technology, Bloomington, Minnesota 55435 (United States); Kaehr, Bryan [Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87106 (United States) [Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87106 (United States); Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Wang Zhou, Xiao; Peter Yang, C.-Y.; Jones, Reese E. [Sandia National Laboratories, Livermore, California 94550 (United States)] [Sandia National Laboratories, Livermore, California 94550 (United States)

    2013-11-18T23:59:59.000Z

    We study the scattering mechanisms driving electron-phonon relaxation in thin gold films via pump-probe time-domain thermoreflectance. Electron-electron scattering can enhance the effective rate of electron-phonon relaxation when the electrons are out of equilibrium with the phonons. In order to correctly and consistently infer electron-phonon coupling factors in films on different substrates, we must account for the increase in steady-state lattice temperature due to laser heating. Our data provide evidence that a thermalized electron population will not directly exchange energy with the substrate during electron-phonon relaxation, whereas this pathway can exist between a non-equilibrium distribution of electrons and a non-metallic substrate.

  11. Determination of the electron–phonon coupling constant in tungsten

    SciTech Connect (OSTI)

    Daraszewicz, Szymon L.; Duffy, Dorothy M.; Shluger, Alexander L. [Department of Physics and Astronomy, London Centre for Nanotechnology, University College London, Gower Street, WC1E 6BT London (United Kingdom); Giret, Yvelin [Department of Physics and Astronomy, London Centre for Nanotechnology, University College London, Gower Street, WC1E 6BT London (United Kingdom); The Institute of Scientific and Industrial Research (ISIR), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 (Japan); Tanimura, Hiroshi; Tanimura, Katsumi [The Institute of Scientific and Industrial Research (ISIR), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 (Japan)

    2014-07-14T23:59:59.000Z

    We used two methods to determine the effective electron-phonon coupling constant (G{sub 0}) in tungsten. Our first principles calculations predict G{sub 0}?=?1.65?×?10{sup 17?}W m{sup ?3} K{sup ?1}. The temporal decay of the femtosecond-resolution optical reflectivity for a (100) surface of bulk W was measured using a pump-probe scheme and analysed using ab initio parameterised two temperature model, which includes both the effects of the electron-phonon coupling and thermal conduction into bulk. This analysis gives G{sub 0}?=?1.4(3)?×?10{sup 17?}W m{sup ?3} K{sup ?1}, in good agreement with the theoretical prediction. The described effective method of calculating and measuring G{sub 0} in bulk materials can be easily extended to other metals.

  12. Anisotropies in Non-Thermal Distortions of Cosmic Light from Photon-Axion Conversion

    E-Print Network [OSTI]

    Guido D'Amico; Nemanja Kaloper

    2015-01-07T23:59:59.000Z

    Ultralight axions which couple sufficiently strongly to photons can leave imprints on the sky at diverse frequencies by mixing with cosmic light in the presence of background magnetic fields. We explore such direction dependent grey-body distortions of the CMB spectrum, enhanced by resonant conditions in the IGM plasma. We also find that if such axions are produced in the early universe and represent a subdominant dark radiation component today, they could convert into X-rays in supervoids, and brighten them at X-ray frequencies.

  13. Anisotropies in Non-Thermal Distortions of Cosmic Light from Photon-Axion Conversion

    E-Print Network [OSTI]

    D'Amico, Guido

    2015-01-01T23:59:59.000Z

    Ultralight axions which couple sufficiently strongly to photons can leave imprints on the sky at diverse frequencies by mixing with cosmic light in the presence of background magnetic fields. We explore such direction dependent grey-body distortions of the CMB spectrum, enhanced by resonant conditions in the IGM plasma. We also find that if such axions are produced in the early universe and represent a subdominant dark radiation component today, they could convert into X-rays in supervoids, and brighten them at X-ray frequencies.

  14. Light storage via coherent population oscillation in a thermal cesium vapor

    E-Print Network [OSTI]

    A. J. F. de Almeida; J. Sales; M. -A. Maynard; T. Laupretre; F. Bretenaker; D. Felinto; F. Goldfarb; J. W. R. Tabosa

    2014-09-19T23:59:59.000Z

    We report on the storage of light via the phenomenon of Coherent Population Oscillation (CPO) in an atomic cesium vapor at room temperature. In the experiment the optical information of a probe field is stored in the CPO of two ground states of a Lambda three-level system formed by the Zeeman sublevels of the hyperfine transition F = 3 - F' = 2 of cesium D2 line. We show directly that this CPO based memory is very insensitive to stray magnetic field inhomogeneities and presents a lifetime which is mainly limited only by atomic motion. A theoretical simulation of the measured spectra was also developed and is in very good agreement with the experiment.

  15. Strain-controlled thermal conductivity in ferroic twinned films

    E-Print Network [OSTI]

    Li, Suzhi

    Large reversible changes of thermal conductivity are induced by mechanical stress, and the corresponding device is a key element for phononics applications. We show that the thermal conductivity ? of ferroic twinned thin ...

  16. Effects of temperature and pressure on phonons in FeSi1–xAlx

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

    Delaire, O.; Al-Qasir, I. I.; Ma, J.; dos Santos, A. M.; Sales, B. C.; Mauger, L.; Stone, M. B.; Abernathy, D. L.; Xiao, Y.; Somayazulu, M.

    2013-05-01T23:59:59.000Z

    The effects of temperature and pressure on phonons in B20 compounds FeSi1–xAlx were measured using inelastic neutron scattering and nuclear-resonant inelastic x-ray scattering. The effect of hole doping through Al substitution is compared to results of alloying with Co (electron doping) in Fe??xCoxSi. While the temperature dependence of phonons in FeSi is highly anomalous, doping with either type of carriers leads to a recovery of the normal quasiharmonic behavior. Density functional theory (DFT) computations of the electronic band structure and phonons were performed. The anomaly in the temperature dependence of the phonons in undoped FeSi was related to the narrowmore »band gap, and its sensitivity to the effect of thermal disordering by phonons. On the other hand, the pressure dependence of phonons at room temperature in undoped FeSi follows the quasiharmonic behavior and is well reproduced by the DFT calculations.« less

  17. Thermal properties of light nuclei from $^{12}$C+$^{12}$C fusion-evaporation reactions

    E-Print Network [OSTI]

    L Morelli; G Baiocco; M D'Agostino; F Gulminelli; M Bruno; U Abbondanno; S Appannababu; S Barlini; M Bini; G Casini; M Cinausero; M Degerlier; D Fabris; N Gelli; F Gramegna; V L Kravchuk; T Marchi; G Pasquali; S Piantelli; S Valdré; Ad R Raduta

    2014-04-14T23:59:59.000Z

    The $^{12}$C+$^{12}$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach calculation allows to select a set of dissipative events which corresponds, to a large extent, to the statistical evaporation of highly excited $^{24}$Mg. Information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain is also extracted. The set of data puts strong constraints on the behaviour of the level density of light nuclei above the threshold for particle emission. In particular, a fast increase of the level density parameter with excitation energy is supported by the data. Residual deviations from a statistical behaviour are seen in two specific channels, and tentatively associated with a contamination from direct reactions and/or $\\alpha$-clustering effects. These channels are studied in further details in the second paper of the series.

  18. Phonon Bottleneck in Graphene-Based Josephson Junctions at Millikelvin...

    Office of Scientific and Technical Information (OSTI)

    Phonon Bottleneck in Graphene-Based Josephson Junctions at Millikelvin Temperatures Citation Details Title: Phonon Bottleneck in Graphene-Based Josephson Junctions at Millikelvin...

  19. acoustic phonon scattering: Topics by E-print Network

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

    type of phononic crystals manufactured Institute of Physics. DOI: 10.10631.2167794 The propagation of acoustic waves in periodic composite Deymier, Pierre 19 Carrier and Phonon...

  20. Thermal and nonthermal melting of silicon under femtosecond x-ray irradiation

    E-Print Network [OSTI]

    Medvedev, Nikita; Ziaja, Beata

    2015-01-01T23:59:59.000Z

    As it is known from visible light experiments, silicon under femtosecond pulse irradiation can undergo the so-called 'nonthermal melting' if the density of electrons excited from the valence to the conduction band overcomes a certain critical value. Such ultrafast transition is induced by strong changes in the atomic potential energy surface, which trigger atomic relocation. However, heating of a material due to the electron-phonon coupling can also lead to a phase transition, called 'thermal melting'. This thermal melting can occur even if the excited-electron density is much too low to induce non-thermal effects. To study phase transitions, and in particular, the interplay of the thermal and nonthermal effects in silicon under a femtosecond x-ray irradiation, we propose their unified treatment by going beyond the Born-Oppenheimer approximation within our hybrid model based on tight binding molecular dynamics. With our extended model we identify damage thresholds for various phase transitions in irradiated s...

  1. Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations

    SciTech Connect (OSTI)

    Nika, Denis L. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States); Cocemasov, Alexandr I. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Balandin, Alexander A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States)

    2014-07-21T23:59:59.000Z

    We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T?phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.

  2. Long-Lived, Coherent Acoustic Phonon Oscillations in GaN Single Crystals

    SciTech Connect (OSTI)

    Wu, S.; Geiser, P.; Jun, J.; Karpinski, J.; Park, J.-R.; Sobolewski, R.

    2006-01-31T23:59:59.000Z

    We report on coherent acoustic phonon (CAP) oscillations studied in high-quality bulk GaN single crystals with a two-color femtosecond optical pump-probe technique. Using a far-above-the-band gap ultraviolet excitation (~270 nm wavelength) and a near-infrared probe beam (~810 nm wavelength), the long-lived, CAP transients were observed within a 10 ns time-delay window between the pump and probe pulses, with a dispersionless (proportional to the probe-beam wave vector) frequency of ~45 GHz. The measured CAP attenuation corresponded directly to the absorption of the probe light in bulk GaN, indicating that the actual (intrinsic) phonon-wave attenuation in our crystals was significantly smaller than the measured 65.8 cm^-1 value. The velocity of the phonon propagation was equal to the velocity of sound in GaN.

  3. Phonon polariton interaction with patterned materials

    E-Print Network [OSTI]

    Statz, Eric R. (Eric Robert)

    2008-01-01T23:59:59.000Z

    The generation, propagation and detection of THz phonon polaritons are studied through both femtosecond pump-probe techniques, and Finite Difference Time Domain (FDTD) simulations in this thesis. The theory surrounding the ...

  4. Phonons and vibrons as markers of the

    E-Print Network [OSTI]

    Marini, Andrea

    ://www.yambo-code.org/andrea Area della Ricerca RM 1, CNR Montelibretti, June 11th 2009 #12;PRB 36, 4821 (1987) 793 K = 68 meV while still debated C. Tarrio, PRB 40, 7852 (1989) 297 K 297 K 83 K 8 K #12;Phonons are responsible" exciton-phonon scattering Ab-Initio polarons #12;Solid St. Comm. 133, 3 (2005) ; PRB 23, 1495 (1981) I

  5. Thermal Conductivity and Large Isotope Effect in GaN from First Principles

    SciTech Connect (OSTI)

    Lindsay, L. [Naval Research Lab. (NRL), Washington, DC (United States); Broido, D. A. [Boston College, Chestnut Hill, MA (United States); Reinecke, T. L. [Naval Research Lab. (NRL), Washington, DC (United States)

    2012-08-01T23:59:59.000Z

    We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, ~65% at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carrying acoustic phonons with optic phonons. This weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap between acoustic and optic phonons compared to other materials. Rigorous understanding of these features in GaN gives important insights into the interplay between intrinsic phonon-phonon scattering and isotopic scattering in a range of materials.

  6. Interface and confined optical phonons in wurtzite nanocrystals Vladimir A. Fonoberov* and Alexander A. Balandin

    E-Print Network [OSTI]

    Fonoberov, Vladimir

    Interface and confined optical phonons in wurtzite nanocrystals Vladimir A. Fonoberov-phonon modes in nanocrystals with a wurtzite crystal structure. It is demonstrated theoretically that, while phonons, the confined polar optical phonons in wurtzite nanocrystals have a discrete spectrum

  7. Maskless direct laser writing with visible light: Breaking through the optical resolving limit with cooperative manipulations of nonlinear reverse saturation absorption and thermal diffusion

    SciTech Connect (OSTI)

    Wei, Jingsong, E-mail: weijingsong@siom.ac.cn [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Wang, Rui [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2014-03-28T23:59:59.000Z

    In this work, the resolving limit of maskless direct laser writing is overcome by cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion, where the nonlinear reverse saturation absorption can induce the formation of below diffraction-limited energy absorption spot, and the thermal diffusion manipulation can make the heat quantity at the central region of energy absorption spot propagate along the thin film thickness direction. The temperature at the central region of energy absorption spot transiently reaches up to melting point and realizes nanolithography. The sample “glass substrate/AgInSbTe” is prepared, where AgInSbTe is taken as nonlinear reverse saturation absorption thin film. The below diffraction-limited energy absorption spot is simulated theoretically and verified experimentally by near-field spot scanning method. The “glass substrate/Al/AgInSbTe” sample is prepared, where the Al is used as thermal conductive layer to manipulate the thermal diffusion channel because the thermal diffusivity coefficient of Al is much larger than that of AgInSbTe. The direct laser writing is conducted by a setup with a laser wavelength of 650?nm and a converging lens of NA=0.85, the lithographic marks with a size of about 100?nm are obtained, and the size is only about 1/10 the incident focused spot. The experimental results indicate that the cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion is a good method to realize nanolithography in maskless direct laser writing with visible light.

  8. Infrared phonon modes in multiferroic single-crystal FeTe2O5Br

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

    Miller, K. H.; Xu, X. S.; Berger, H.; Craciun, V.; Xi, Xiaoxiang; Martin, C.; Carr, G. L.; Tanner, D. B.

    2013-06-01T23:59:59.000Z

    Reflection and transmission as a function of temperature (7–300 K and 5–300 K respectively) have been measured on single crystals of the multiferroic compound FeTe2O5Br utilizing light spanning from the far infrared to the visible. The complex dielectric function and other optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. Analysis of the anisotropic excitation spectra via Drude-Lorentz fitting and lattice dynamical calculations have led to the observation of 43 of the 53 modes predicted along the b axis of the monoclinic cell. The phonon response parallel to the a and c axes are also presented. Assignments to groups (clusters) of phonons have been made and trends within them are discussed in light of our calculated displacement patterns.

  9. Microscopic model of a phononic refrigerator

    E-Print Network [OSTI]

    Liliana Arrachea; Eduardo Mucciolo; Claudio Chamon; Rodrigo Capaz

    2012-11-05T23:59:59.000Z

    We analyze a simple microscopic model to pump heat from a cold to a hot reservoir in a nanomechanical system. The model consists of a one-dimensional chain of masses and springs coupled to a back gate through which a time-dependent perturbation is applied. The action of the gate is to modulate the coupling of the masses to a substrate via additional springs that introduce a moving phononic barrier. We solve the problem numerically using non-equilibrium Green function techniques. For low driving frequencies and for sharp traveling barriers, we show that this microscopic model realizes a phonon refrigerator.

  10. Deviational simulation of phonon transport in graphene ribbons with ab initio scattering

    SciTech Connect (OSTI)

    Landon, Colin D.; Hadjiconstantinou, Nicolas G. [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-10-28T23:59:59.000Z

    We present a deviational Monte Carlo method for solving the Boltzmann-Peierls equation with ab initio 3-phonon scattering, for temporally and spatially dependent thermal transport problems in arbitrary geometries. Phonon dispersion relations and transition rates for graphene are obtained from density functional theory calculations. The ab initio scattering operator is simulated by an energy-conserving stochastic algorithm embedded within a deviational, low-variance Monte Carlo formulation. The deviational formulation ensures that simulations are computationally feasible for arbitrarily small temperature differences, while the stochastic treatment of the scattering operator is both efficient and exhibits no timestep error. The proposed method, in which geometry and phonon-boundary scattering are explicitly treated, is extensively validated by comparison to analytical results, previous numerical solutions and experiments. It is subsequently used to generate solutions for heat transport in graphene ribbons of various geometries and evaluate the validity of some common approximations found in the literature. Our results show that modeling transport in long ribbons of finite width using the homogeneous Boltzmann equation and approximating phonon-boundary scattering using an additional homogeneous scattering rate introduces an error on the order of 10% at room temperature, with the maximum deviation reaching 30% in the middle of the transition regime.

  11. Point source in a phononic grating: stop bands give rise to phonon-focusing caustics

    E-Print Network [OSTI]

    Maznev, Alex

    We use locally-excited gigahertz surface phonon wavepackets in microscopic line structures of different pitches to reveal profound anisotropy in the radiation pattern of a point source in a grating. Time-domain data obtained ...

  12. The phonon density of states of (alpha) and (delta)-Plutonium by inelastic x-ray scattering

    SciTech Connect (OSTI)

    Manley, M E; Said, A; Fluss, M J; Wall, M; Lashley, J C; Alatas, A; Moore, K T

    2008-10-08T23:59:59.000Z

    Inelastic x-ray scattering measurements of the phonon density of states (DOS) were performed on polycrystalline samples of pure {alpha}-Pu and {delta}-Pu{sub 0.98}Ga{sub 0.02} at room temperature. The heat capacity of {alpha}-Pu is well reproduced by contributions calculated from the measured phonon DOS plus conventional thermal expansion and electronic contributions, showing that {alpha}-Pu is a 'well-behaved' metal in this regard. A comparison of the phonon DOS of the two phases at room temperature surprised us in that the vibrational entropy difference between them is only a quarter of the total entropy difference expected from known thermodynamic measurements. The missing entropy is too large to be accounted for by conventional electronic entropy and evidence from the literature rules out a contribution from spin fluctuations. Possible alternative sources for the missing entropy are discussed.

  13. Establishment of correlated states in a quantum dot interacting with an acoustic phonon reservoir

    E-Print Network [OSTI]

    Hui Huang; Gao-xiang Li; Wen-ju Gu; Zbigniew Ficek

    2014-08-20T23:59:59.000Z

    We investigate the effects of a low frequency (acoustic) phonon bath on the dynamics of a quantum dot modelled as a cascade three-level system. We show that the phonon bath appears to the upper transition of the cascade system as a broadband reservoir of inverted rather than conventional harmonic oscillators. The action of the annihilation and creation operators of the inverted oscillator are interchanges relative to those of the usual harmonic oscillator that it serves as a linear amplifier to the system, and thereby gives rise to unusual features in the dynamics of the quantum dot. We find that the phonon bath, although being in a thermal state, affects the quantum dot as a correlated-type reservoir which results in the decay of the system to a correlated two-photon state with the population distribution no longer obeying a Boltzmann distribution. It is particularly interesting that even for a zero temperature phonon reservoir the steady state is a correlated state which under appropriate conditions on the Rabi frequencies and the damping rates can reduce to a strongly correlated pure state. It is shown that the two-photon correlations result in a significant squeezing and strong two-photon correlations in the radiation field emitted by the quantum dot. The presence of the correlations in the system is manifest in the presence of quantum beats in the time evolution of the populations and the radiation intensity. The effect of the ordinary spontaneous emission on the features induced by the phonon bath is also discussed.

  14. Frequency stabilization of the zero-phonon line of a quantum dot via phonon-assisted active feedback

    E-Print Network [OSTI]

    Jack Hansom; Carsten H. H. Schulte; Clemens Matthiesen; Megan Stanley; Mete Atature

    2014-10-17T23:59:59.000Z

    We report on the feedback stabilization of the zero-phonon emission frequency of a single InAs quantum dot. The spectral separation of the phonon-assisted component of the resonance fluorescence provides a probe of the detuning between the zero-phonon transition and the resonant driving laser. Using this probe in combination with active feedback, we stabilize the zero-phonon transition frequency against environmental fluctuations. This protocol reduces the zero-phonon fluorescence intensity noise by a factor of 22 by correcting for environmental noise with a bandwidth of 191 Hz, limited by the experimental collection efficiency. The associated sub-Hz fluctuations in the zero-phonon central frequency are reduced by a factor of 7. This technique provides a means of stabilizing the quantum dot emission frequency without requiring access to the zero-phonon emission.

  15. 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)

    2014-07-07T23:59:59.000Z

    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.

  16. Mode dependent lattice thermal conductivity of single layer graphene

    SciTech Connect (OSTI)

    Wei, Zhiyong; Yang, Juekuan; Bi, Kedong; Chen, Yunfei, E-mail: yunfeichen@seu.edu.cn [Jiangsu Key Laboratory for Design and Manufacture of Micro/Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University, Nanjing 210096 (China)

    2014-10-21T23:59:59.000Z

    Molecular dynamics simulation is performed to extract the phonon dispersion and phonon lifetime of single layer graphene. The mode dependent thermal conductivity is calculated from the phonon kinetic theory. The predicted thermal conductivity at room temperature exhibits important quantum effects due to the high Debye temperature of graphene. But the quantum effects are reduced significantly when the simulated temperature is as high as 1000 K. Our calculations show that out-of-plane modes contribute about 41.1% to the total thermal conductivity at room temperature. The relative contribution of out-of-plane modes has a little decrease with the increase of temperature. Contact with substrate can reduce both the total thermal conductivity of graphene and the relative contribution of out-of-plane modes, in agreement with previous experiments and theories. Increasing the coupling strength between graphene and substrate can further reduce the relative contribution of out-of-plane modes. The present investigations also show that the relative contribution of different mode phonons is not sensitive to the grain size of graphene. The obtained phonon relaxation time provides useful insight for understanding the phonon mean free path and the size effects in graphene.

  17. Neutron Scattering Study of Anharmonic Phonon Dynamics in Thermoelectr...

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

    4:10 pm LOCATION: Physics 0003 Understanding the Electroweak Symmetry Breaking: The Higgs Boson and Beyond, Chen Li, Oak Ridge National Laboratory Knowledge on phonon...

  18. Anomalous diameter dependence of thermal transport in ultra-narrow Si nanowires

    SciTech Connect (OSTI)

    Karamitaheri, Hossein, E-mail: karami@iue.tuwien.ac.at [Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, A-1040 Wien (Austria); Department of Electrical Engineering, University of Kashan, Kashan, 87317-51167 (Iran, Islamic Republic of); Neophytou, Neophytos, E-mail: neophytou@iue.tuwien.ac.at [Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, A-1040 Wien (Austria); School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom); Kosina, Hans, E-mail: kosina@iue.tuwien.ac.at [Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, A-1040 Wien (Austria)

    2014-01-14T23:59:59.000Z

    We present atomistic valence force field calculations of thermal transport in Si nanowires of diameters from 12?nm down to 1?nm. We show that as the diameter is reduced, the phonon density-of-states and transmission function acquire a finite value at low frequency, in contrast to approaching zero as in the bulk material. It turns out that this effect results in what Ziman described as the “problem of long longitudinal waves” [J. M. Ziman, Electrons and Phonons: The Theory of Transport Phenomena in Solids (Clarendon, Oxford, 1962)], which states that the thermal conductivity of a material increases as its length is increased due to the vanishing scattering for long-wavelength phonons. We show that this thermal transport improvement also appears in nanowires as their diameter is decreased below D?=?5?nm (not only as the length increases), originating from the increase in the density of the long wavevector modes. The observation is present under ballistic transport conditions, and further enhanced with the introduction of phonon-phonon scattering. Because of this, in such ultra-narrow nanowires, as the diameter is reduced, phonon transport is dominated more and more by lower energy phonons with longer mean-free paths. We show that ?80% of the heat is carried by phonons with energies less than 5?meV, most with mean-free paths of several hundreds of nanometers.

  19. Laser lift-off technique for freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN and its application to light-emitting diodes

    SciTech Connect (OSTI)

    Iida, Daisuke, E-mail: dft0tfi16@meijo-u.ac.jp; Kawai, Syunsuke; Ema, Nobuaki; Tsuchiya, Takayoshi; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi [Faculty of Science and Technology, Meijo University, Nagoya 468-8502 (Japan); Akasaki, Isamu [Faculty of Science and Technology, Meijo University, Nagoya 468-8502 (Japan); Akasaki Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2014-08-18T23:59:59.000Z

    We developed a laser lift-off technique for a freestanding GaN substrate using an In droplet formed by thermal decomposition of GaInN. A combination of an In droplet formed by thermal decomposition of GaInN during growth and a pulsed second-harmonic neodymium-doped yttrium aluminum garnet laser (??=?532?nm) realized the lift-off GaN substrate. After laser lift-off of the GaN substrate, it was used to achieve 380?nm ultraviolet light-emitting diodes with light output enhanced 1.7-fold. In this way, the light extraction can be improved by removing the GaN substrate.

  20. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect (OSTI)

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)] [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2014-02-15T23:59:59.000Z

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  1. High efficiency incandescent lighting

    DOE Patents [OSTI]

    Bermel, Peter; Ilic, Ognjen; Chan, Walker R.; Musabeyoglu, Ahmet; Cukierman, Aviv Ruben; Harradon, Michael Robert; Celanovic, Ivan; Soljacic, Marin

    2014-09-02T23:59:59.000Z

    Incandescent lighting structure. The structure includes a thermal emitter that can, but does not have to, include a first photonic crystal on its surface to tailor thermal emission coupled to, in a high-view-factor geometry, a second photonic filter selected to reflect infrared radiation back to the emitter while passing visible light. This structure is highly efficient as compared to standard incandescent light bulbs.

  2. A phonon thermodynamics approach of gold nanofluids synthesized in solution plasma

    SciTech Connect (OSTI)

    Heo, YongKang, E-mail: yk@rd.numse.nagoya-u.ac.jp; Aburaya, Daiki, E-mail: daiki@rd.numse.nagoya-u.ac.jp [Graduate School of Materials Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Antoaneta Bratescu, Maria, E-mail: maria@rd.numse.nagoya-u.ac.jp [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Saito, Nagahiro, E-mail: hiro@rd.numse.nagoya-u.ac.jp [Graduate School of Materials Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Green Mobility Collaborative Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); CREST, Japan Science and Technology Agency, Gobancho, Chiyoda-ku, Tokyo 102-8666 (Japan)

    2014-03-17T23:59:59.000Z

    The phonon thermodynamics theory for liquids was applied to explain the thermal characteristics of gold nanofluids synthesized by a simple, one-step, and chemical-free method using an electrical discharge in a liquid environment termed solution plasma process. The specific heat capacity of nanofluids was measured with a differential scanning calorimeter using the ratio between the differential heat flow rate and the heating rate. The decrease of the specific heat capacity with 10% of gold nanofluids relative to water was explained by the decrease of Frenkel relaxation time with 22%, considering a solid-like state model of liquids.

  3. Thermal conductivity of configurable two-dimensional carbon nanotube architecture and strain modulation

    SciTech Connect (OSTI)

    Zhan, H. F.; Bell, J. M.; Gu, Y. T., E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George St., Brisbane, Queensland 4000 (Australia); Zhang, G. [Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632 (Singapore)

    2014-10-13T23:59:59.000Z

    We reported the thermal conductivity of the two-dimensional carbon nanotube (CNT)-based architecture, which can be constructed through welding of single-wall CNTs by electron beam. Using large-scale nonequilibrium molecular dynamics simulations, the thermal conductivity is found to vary with different junction types due to their different phonon scatterings at the junction. The strong length and strain dependence of the thermal conductivity suggests an effective avenue to tune the thermal transport properties of the CNT-based architecture, benefiting the design of nanoscale thermal rectifiers or phonon engineering.

  4. Phonon Mediated Off-Resonant Quantum Dot-Cavity Coupling

    E-Print Network [OSTI]

    Arka Majumdar; Yiyang Gong; Erik D. Kim; Jelena Vuckovic

    2010-12-14T23:59:59.000Z

    A theoretical model for the phonon-mediated off-resonant coupling between a quantum dot and a cavity, under resonant excitation of the quantum dot, is presented. We show that the coupling is caused by electron-phonon interaction in the quantum dot and is enhanced by the cavity. We analyze recently observed resonant quantum dot spectroscopic data by our theoretical model.

  5. Calculated Phonon Spectra of Plutonium at High Temperatures

    E-Print Network [OSTI]

    Savrasov, Sergej Y.

    Calculated Phonon Spectra of Plutonium at High Temperatures X. Dai,1 S. Y. Savrasov,2 * G. Kotliar dynamical proper- ties of plutonium using an electronic structure method, which incorporates correlation anharmonic and can be stabilized at high temperatures by its phonon entropy. Plutonium (Pu) is a material

  6. Non-thermal Plasma Chemistry Non-thermal Thermal

    E-Print Network [OSTI]

    Greifswald, Ernst-Moritz-Arndt-Universität

    -thermal Plasma Chemical Flow Reactor #12;Werner von Siemens ,, ... construction of an apparatus generation (1857) pollution control volatile organic components, NOx reforming, ... radiation sources excimer;Leuchtstoffröhre Plasma-Bildschirm Energiesparlampe #12;electrical engineering light sources textile industry

  7. Ultrafast relaxation dynamics of hot optical phonons in graphene Haining Wang,1,a

    E-Print Network [OSTI]

    Afshari, Ehsan

    of the coupled carrier-phonon system with rate equations and find a good agreement between the experimental data phonons which then present the main bottleneck to subsequent cooling. Optical phonon cooling on short time between 2­3 ps were reported for both zone-center E2g and zone-edge A1 modes for phonon temperatures

  8. Bidirectional and tunable single-photons multi-channel quantum router between microwave and optical light

    E-Print Network [OSTI]

    Peng-Cheng Ma; Jian-Qi Zhang; Mang Feng; Zhi-Ming Zhang

    2014-10-16T23:59:59.000Z

    Routing of photon play a key role in optical communication and quantum networks. Although the quantum routing of signals has been investigated in various systems both in theory and experiment. However, no current theory can route quantum signals between microwave and optical light. Here, we propose an experimentally accessible tunable multi-channel quantum routing proposal using photon-phonon translation in a hybrid opto-electromechanical system. It is the first demonstration that the single-photon of optical frequency can be routed into three different output ports by adjusting microwave power. More important, the two output signals can be selected according to microwave power. Meanwhile, we also demonstrate the vacuum and thermal noise will be insignificant for the optical performance of the single-photon router at temperature of the order of 20 mK. Our proposal may have paved a new avenue towards multi-channel router and quantum network.

  9. Thermal trim for luminaire

    DOE Patents [OSTI]

    Bazydola, Sarah; Ghiu, Camil-Daniel; Harrison, Robert; Jeswani, Anil

    2013-11-19T23:59:59.000Z

    A luminaire with a thermal pathway to reduce the junction temperature of the luminaire's light source, and methods for so doing, are disclosed. The luminaire includes a can, a light engine, and a trim, that define a substantially continuous thermal pathway from the light engine to a surrounding environment. The can defines a can cavity and includes a can end region. The light engine is within the can cavity and includes a light source and a heat sink, including a heat sink end region, coupled thereto. The trim is at least partially disposed within the can cavity and includes a first trim end region coupled to the heat sink end region and a second trim end region coupled to the can end region. Thermal interface material may be located between: the heat sink and the trim, the trim and the can, and/or the heat sink and the light source.

  10. The Electron-Phonon Interaction as Studied by Photoelectron Spectroscopy

    SciTech Connect (OSTI)

    D.W. Lynch

    2004-09-30T23:59:59.000Z

    With recent advances in energy and angle resolution, the effects of electron-phonon interactions are manifest in many valence-band photoelectron spectra (PES) for states near the Fermi level in metals.

  11. Thermal conductivity of graphene nanoribbons in noble gaseous environments

    SciTech Connect (OSTI)

    Zhong, Wei-Rong, E-mail: wrzhong@hotmail.com; Xu, Zhi-Cheng; Zheng, Dong-Qin [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn [Laboratory of Quantum Information Technology, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China)

    2014-02-24T23:59:59.000Z

    We investigate the thermal conductivity of suspended graphene nanoribbons in noble gaseous environments using molecular dynamics simulations. It is reported that the thermal conductivity of perfect graphene nanoribbons decreases with the gaseous pressure. The decreasing is more obvious for the noble gas with large atomic number. However, the gaseous pressure cannot change the thermal conductivity of defective graphene nanoribbons apparently. The phonon spectra of graphene nanoribbons are also provided to give corresponding supports.

  12. Heart - Shaped Nuclei: Condensation of Rotational Aligned Octupole Phonons

    E-Print Network [OSTI]

    S. Frauendorf

    2007-10-24T23:59:59.000Z

    The strong octupole correlations in the mass region $A\\approx 226$ are interpreted as rotation-induced condensation of octupole phonons having their angular momentum aligned with the rotational axis. Discrete phonon energy and parity conservation generate oscillations of the energy difference between the lowest rotational bands with positive and negative parity. Anharmonicities tend to synchronize the the rotation of the condensate and the quadrupole shape of the nucleus forming a rotating heart shape.

  13. Phonon dispersion curves determination in (delta)-phase Pu-Ga alloys

    SciTech Connect (OSTI)

    Wong, J; Clatterbuck, D; Occelli, F; Farber, D; Schwartz, A; Wall, M; Boro, C; Krisch, M; Beraud, A; Chiang, T; Xu, R; Hong, H; Zschack, P; Tamura, N

    2006-02-07T23:59:59.000Z

    We have designed and successfully employed a novel microbeam on large grain sample concept to conduct high resolution inelastic x-ray scattering (HRIXS) experiments to map the full phonon dispersion curves of an fcc {delta}-phase Pu-Ga alloy. This approach obviates experimental difficulties with conventional inelastic neutron scattering due to the high absorption cross section of the common {sup 239}Pu isotope and the non-availability of large (mm size) single crystal materials for Pu and its alloys. A classical Born von-Karman force constant model was used to model the experimental results, and no less than 4th nearest neighbor interactions had to be included to account for the observation. Several unusual features including, a large elastic anisotropy, a small shear elastic modulus, (C{sub 11}-C{sub 12})/2, a Kohn-like anomaly in the T{sub 1}[011] branch, and a pronounced softening of the T[111] branch towards the L point in the Brillouin are found. These features may be related to the phase transitions of plutonium and to strong coupling between the crystal structure and the 5f valence instabilities. Our results represent the first full phonon dispersions ever obtained for any Pu-bearing material, thus ending a 40-year quest for this fundamental data. The phonon data also provide a critical test for theoretical treatments of highly correlated 5f electron systems as exemplified by recent dynamical mean field theory (DMFT) calculations for {delta}-plutonium. We also conducted thermal diffuse scattering experiments to study the T(111) dispersion at low temperatures with an attempt to gain insight into bending of the T(111) branch in relationship to the {delta} {yields} {alpha}{prime} transformation.

  14. Contact thermal lithography

    E-Print Network [OSTI]

    Schmidt, Aaron Jerome, 1979-

    2004-01-01T23:59:59.000Z

    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 ...

  15. On virtual phonons, photons and electrons

    E-Print Network [OSTI]

    G. Nimtz

    2009-07-09T23:59:59.000Z

    A macroscopic realization of the strange virtual particles is presented. The classical Helmholtz and the quantum mechanical Schr\\"odinger equations are analogous differential equations. Their imaginary solutions are called evanescent modes in the case of elastic and electromagnetic fields. In the case of non-relativistic quantum mechanical fields they are called tunneling solutions. The imaginary solutions of this differential equation point to strange consequences: They are non local, they are not observable, and they described as virtual particles. During the last two decades QED calculations of the imaginary solutions have been experimentally confirmed for phonons, photons, and for electrons. The experimental proofs of the predictions of the non-relativistic quantum mechanics and of the Wigner phase time approach for the elastic, the electromagnetic and the Schr\\"odinger fields will be presented in this article. The results are zero tunneling time and an interaction time (i.e. a phase shift) at the barrier interfaces. The measured barrier interaction time (i.e. the barrier transmission time) scales approximately inversely with the particle energy.

  16. Hydrodynamic phonon transport in suspended graphene

    E-Print Network [OSTI]

    Lee, Sangyeop

    Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier’s law through observations of ballistic transport. Despite its unique features, another instance of the breakdown of Fourier’s ...

  17. Nanoscale thermal transport. II. 2003–2012

    SciTech Connect (OSTI)

    Cahill, David G., E-mail: d-cahill@illinois.edu; Braun, Paul V. [Department of Materials Science and Engineering and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Chen, Gang [Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139 (United States); Clarke, David R. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Fan, Shanhui [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Goodson, Kenneth E. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Keblinski, Pawel [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); King, William P. [Department of Mechanical Sciences and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Mahan, Gerald D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Majumdar, Arun [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Maris, Humphrey J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Phillpot, Simon R. [Department of Materials Science and Engineering, University of Florida, Gainseville, Florida 32611 (United States); Pop, Eric [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Shi, Li [Department of Mechanical Engineering, University of Texas, Autin, Texas 78712 (United States)

    2014-03-15T23:59:59.000Z

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ?1?nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal analysis using proximal probes has achieved spatial resolution of 10?nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

  18. Indoor air movement acceptability and thermal comfort in hot-humid climates

    E-Print Network [OSTI]

    Candido, Christhina Maria

    2010-01-01T23:59:59.000Z

    HVAC) and the thermal envelope of buildings, but designments concern the thermal envelope, lighting and acoustics,HVAC and building’s thermal envelope. Yet requirements for

  19. Basal-plane thermal conductivity of few-layer molybdenum disulfide

    SciTech Connect (OSTI)

    Jo, Insun; Ou, Eric; Shi, Li, E-mail: lishi@mail.utexas.edu [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Pettes, Michael Thompson [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering and the Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Wu, Wei [Department of Mechanical Engineering and the Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-05-19T23:59:59.000Z

    We report the in-plane thermal conductivity of suspended exfoliated few-layer molybdenum disulfide (MoS{sub 2}) samples that were measured by suspended micro-devices with integrated resistance thermometers. The obtained room-temperature thermal conductivity values are (44–50) and (48–52) W m{sup ?1} K{sup ?1} for two samples that are 4 and 7 layers thick, respectively. For both samples, the peak thermal conductivity occurs at a temperature close to 120?K, above which the thermal conductivity is dominated by intrinsic phonon-phonon scattering although phonon scattering by surface disorders can still play an important role in these samples especially at low temperatures.

  20. Unraveling the interlayer-related phonon self-energy renormalization in bilayer graphene

    E-Print Network [OSTI]

    Araujo, Paulo Antonio Trinidade

    In this letter, we present a step towards understanding the bilayer graphene (2LG) interlayer (IL)-related phonon combination modes and overtones as well as their phonon self-energy renormalizations by using both gate-modulated ...

  1. Energy transmission through and along thin films mediated by surface phonon-polaritons

    E-Print Network [OSTI]

    Chen, Dye-Zone A. (Dye-Zone Abraham), 1973-

    2007-01-01T23:59:59.000Z

    Surface phonon-polaritons are hybrid electromagnetic modes that are the result of photons coupling to transverse optical phonons. Recently, these surface modes have received much renewed interest primarily due to the fact ...

  2. Active Thermal Extraction of Near-field Thermal Radiation

    E-Print Network [OSTI]

    Ding, Ding

    2015-01-01T23:59:59.000Z

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. Our study demonstrates a new approach to manipulate thermal radiation that could find applications in thermal management.

  3. Anharmonic phonons and magnons in BiFeO3

    SciTech Connect (OSTI)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL; Stone, Matthew B [ORNL; Huq, Ashfia [ORNL; Gout, Delphine J [ORNL; Brown, Craig [National Institute of Standards and Technology (NIST); Wang, Kefeng [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Ren, Zhifeng [Boston College, Chestnut Hill

    2012-01-01T23:59:59.000Z

    The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO3 were measured for temperatures 200 < T < 750K , using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO3 closely resembles that of similar Fe perovskites, such as LaFeO3, despite the cycloid modulation in BiFeO3. We do not find any evidence for a spin gap. A strong T-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

  4. Overcoming phonon-induced dephasing for indistinguishable photon sources

    E-Print Network [OSTI]

    Tom Close; Erik M. Gauger; Brendon W. Lovett

    2012-06-25T23:59:59.000Z

    Reliable single photon sources constitute the basis of schemes for quantum communication and measurement based quantum computing. Solid state single photon sources based on quantum dots are convenient and versatile but the electronic transitions that generate the photons are subject to interactions with lattice vibrations. Using a microscopic model of electron-phonon interactions and a quantum master equation, we here examine phonon-induced decoherence and assess its impact on the rate of production, and indistinguishability, of single photons emitted from an optically driven quantum dot system. We find that, above a certain threshold of desired indistinguishability, it is possible to mitigate the deleterious effects of phonons by exploiting a three-level Raman process for photon production.

  5. Theory of phonon dynamics in an ion trap

    E-Print Network [OSTI]

    Dutta, T; Sengupta, K

    2015-01-01T23:59:59.000Z

    We develop a theory to address the non-equilibrium dynamics of phonons in a one-dimensional trapped ion system. We elaborate our earlier results obtained in Phys. Rev. Lett. {\\bf 111}, 170406 (2013) to chart out the mechanism of dynamics-induced cooling and entanglement generation between phonons in these systems when subjected to a linear ramp protocol inducing site-specific tuning of on-site interactions between the phonons. We further extend these studies to non-linear ramps and periodic drive protocols and identify the optimal ramp protocol for minimal cooling and entanglement generation time. We qualitatively address the effect of noise arising out of fluctuation of the intensity of the laser used to generate entanglement and provide a detailed discussion of a realistic experimental setup which may serve as a test bed for our theory.

  6. Existence of an independent phonon bath in a quantum device L. M. A. Pascal,1

    E-Print Network [OSTI]

    Recanati, Catherine

    isolated from each other by a 40 nm thick layer of Si. (c) Heat transfer model. Electrons and phonons

  7. Phonon-assisted robust and deterministic two-photon biexciton preparation in a quantum dot

    E-Print Network [OSTI]

    S. Bounouar; M. Müller; A. M. Barth; M. Glässl; V. M. Axt; P. Michler

    2014-08-29T23:59:59.000Z

    We investigate both experimentally and theoretically a simple yet more robust and flexible alternative to Rabi oscillation-type biexciton preparation protocols traditionally used for semiconductor quantum dots. The quantum dot is excited by a strong laser pulse positively detuned from the two-photon resonance yielding an on demand initialization of the biexciton state by making use of the phonon-induced thermalization of the photon dressed states. It is shown that for excitation pulses in the picosecond range, a stable and high fidelity of up to $f_{XX}=0.98\\pm 0.01$ is reached. Notably, the generated photons show similar coherence properties as measured in the resonant two-photon scheme. This protocol is a powerful tool for the control of complex solid state systems combining radiative cascades, entanglement and resonant cavity modes.

  8. Infrared phonon modes in multiferroic single-crystal FeTe2O5Br

    SciTech Connect (OSTI)

    Miller, K. H.; Xu, X. S.; Berger, H.; Craciun, V.; Xi, Xiaoxiang; Martin, C.; Carr, G. L.; Tanner, D. B.

    2013-06-01T23:59:59.000Z

    Reflection and transmission as a function of temperature (7–300 K and 5–300 K respectively) have been measured on single crystals of the multiferroic compound FeTe2O5Br utilizing light spanning from the far infrared to the visible. The complex dielectric function and other optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. Analysis of the anisotropic excitation spectra via Drude-Lorentz fitting and lattice dynamical calculations have led to the observation of 43 of the 53 modes predicted along the b axis of the monoclinic cell. The phonon response parallel to the a and c axes are also presented. Assignments to groups (clusters) of phonons have been made and trends within them are discussed in light of our calculated displacement patterns.

  9. Temperature Dependent Magnon-Phonon Coupling in bcc Fe from Theory and Experiment

    E-Print Network [OSTI]

    Tai, Yu-Chong

    elucidate magnon-phonon coupling. Neutron scattering experiments of phonon dispersions have provided important data at selected temperatures [11]. Nuclear resonant inelastic x-ray scattering measurements performed nuclear resonant inelastic x-ray scattering measurements of the phonon density of states of bcc Fe

  10. Thermal Fluctuations and Rubber Elasticity

    E-Print Network [OSTI]

    Xiangjun Xing; Paul M. Goldbart; Leo Radzihovsky

    2006-09-21T23:59:59.000Z

    The effects of thermal elastic fluctuations in rubber materials are examined. It is shown that, due to an interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation, and shows a good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.

  11. Exploiting structured environments for efficient energy transfer: The phonon antenna mechanism

    E-Print Network [OSTI]

    M. del Rey; A. W. Chin; S. F. Huelga; M. B. Plenio

    2012-11-29T23:59:59.000Z

    A non-trivial interplay between quantum coherence and dissipative environment-driven dynamics is becoming increasingly recognised as key for efficient energy transport in photosynthetic pigment-protein complexes, and converting these biologically-inspired insights into a set of design principles that can be implemented in artificial light-harvesting systems has become an active research field. Here we identify a specific design principle - the phonon antenna - that demonstrates how inter-pigment coherence is able to modify and optimize the way that excitations spectrally sample their local environmental fluctuations. We place this principle into a broader context and furthermore we provide evidence that the Fenna-Matthews-Olson complex of green sulphur bacteria has an excitonic structure that is close to such an optimal operating point, and suggest that this general design principle might well be exploited in other biomolecular systems.

  12. Freie Universitt Berlin Transient reflectivity and coherent phonon

    E-Print Network [OSTI]

    Wolf, Martin

    Freie Universität Berlin Transient reflectivity and coherent phonon excitation: An ultrafast probe-Hubbard? . . . . . . 35 1.3.3 The photoinduced phase transition . . . . . . . . . . . . . . . . . . . 36 I #12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.1.1 Generation of ultrashort laser pulses: the mode-locked Ti:Sapphire oscillator

  13. Phonon-enhanced crystal growth and lattice healing

    DOE Patents [OSTI]

    Buonassisi, Anthony; Bertoni, Mariana; Newman, Bonna

    2013-05-28T23:59:59.000Z

    A system for modifying dislocation distributions in semiconductor materials is provided. The system includes one or more vibrational sources for producing at least one excitation of vibrational mode having phonon frequencies so as to enhance dislocation motion through a crystal lattice.

  14. Combining Pattern Instability and Shape-Memory Hysteresis for Phononic

    E-Print Network [OSTI]

    Combining Pattern Instability and Shape-Memory Hysteresis for Phononic Switching Ji-Hyun Jang Received April 10, 2009 ABSTRACT We report a fully reversible and robust shape-memory effect in a two simulations correctly capture the three steps of the shape-memory cycle observed experimentally. Structures

  15. Enhanced Electron-Phonon Coupling at Metal Surfaces

    SciTech Connect (OSTI)

    Plummer, Ward E.

    2010-08-04T23:59:59.000Z

    The Born-Oppenheimer approximation (BOA) decouples electronic from nuclear motion, providing a focal point for most quantum mechanics textbooks. However, a multitude of important chemical, physical and biological phenomena are driven by violations of this approximation. Vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond, for example, conventional catalysis or enzymatically delivered biological reactions. Metastable phenomena associated with defects and dopants in semiconductors, oxides, and glasses entail violation of the BOA. Charge exchange in inorganic polymers, organic slats and biological systems involves charge- induced distortions of the local structure. A classic example is conventional superconductivity, which is driven by the electron-lattice interaction. High-resolution angle-resolved photoemission experiments are yielding new insight into the microscopic origin of electron-phonon coupling (EPC) in anisotropic two-dimensional systems. Our recent surface phonon measurement on the surface of a high-Tc material clearly indicates an important momentum dependent EPC in these materials. In the last few years we have shifted our research focus from solely looking at electron phonon coupling to examining the structure/functionality relationship at the surface of complex transition metal compounds. The investigation on electron phonon coupling has allowed us to move to systems where there is coupling between the lattice, the electrons and the spin.

  16. Light Steel Framing: Improving the Integral Design 

    E-Print Network [OSTI]

    Amundarain, Aitor; Torero, Jose L; Usmani, Asif; Al-Remal, Ahmad M

    2006-09-11T23:59:59.000Z

    Light Steel Framing has been extensively used in cold climate countries due to its good thermal and structural behaviour. Improved thermal behaviour results in positive environmental impact essential for sustainable ...

  17. Phonon dispersion and quantization tuning of strained carbon nanotubes for flexible electronics

    SciTech Connect (OSTI)

    Gautreau, Pierre; Chu, Yanbiao; Basaran, Cemal [Electronic Packaging Laboratory, State University of New York at Buffalo, 102 Ketter Hall, Buffalo, New York 14260 (United States); Ragab, Tarek [Electronic Packaging Laboratory, State University of New York at Buffalo, 102 Ketter Hall, Buffalo, New York 14260 (United States); Nanotechnology Research Laboratory, University of Tabuk, Tabuk, 71491, Saudi Arabia and Faculty of Engineering, Alexandria University, Alexandria 21526 (Egypt)

    2014-06-28T23:59:59.000Z

    Graphene and carbon nanotubes are materials with large potentials for applications in flexible electronics. Such devices require a high level of sustainable strain and an understanding of the materials electrical properties under strain. Using supercell theory in conjunction with a comprehensive molecular mechanics model, the full band phonon dispersion of carbon nanotubes under uniaxial strain is studied. The results suggest an overall phonon softening and open up the possibility of phonon quantization tuning with uniaxial strain. The change in phonon quantization and the resulting increase in electron-phonon and phonon-phonon scattering rates offer further explanation and theoretical basis to the experimental observation of electrical properties degradation for carbon nanotubes under uniaxial strain.

  18. Battle against Phonons (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum

    ScienceCinema (OSTI)

    Chen, Gang (Director, Solid-State Solar-Thermal Energy Conversion Center); S3TEC Staff

    2011-11-02T23:59:59.000Z

    'Battle against Phonons' was submitted by the Solid-State Solar-Thermal Energy Conversion (S3TEC) EFRC to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. This video was selected as one of five winners by a distinguished panel of judges for the special award, 'Best with Popcorn'. S3TEC, an EFRC directed by Gang Chen at the Massachusetts Institute of Technology is a partnership of scientists from four research institutions: MIT (lead), Oak Ridge National Laboratory, Boston College, and Rensselaer Polytechnic Institute. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of the Solid-State Solar Thermal Energy Conversion Center is 'to create novel, solid-state materials for the conversion of sunlight into electricity using thermal and photovoltaic processes.' Research topics are: solar photovoltaic, photonic, metamaterial, optics, solar thermal, thermoelectric, phonons, thermal conductivity, defects, ultrafast physics, interfacial characterization, matter by design, novel materials synthesis, charge transport, defect tolerant materials, and scalable processing.

  19. Catalytic thermal barrier coatings

    DOE Patents [OSTI]

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

    2009-06-02T23:59:59.000Z

    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.

  20. Solid state lighting component

    DOE Patents [OSTI]

    Yuan, Thomas; Keller, Bernd; Ibbetson, James; Tarsa, Eric; Negley, Gerald

    2010-10-26T23:59:59.000Z

    An LED component comprising an array of LED chips mounted on a planar surface of a submount with the LED chips capable of emitting light in response to an electrical signal. The LED chips comprise respective groups emitting at different colors of light, with each of the groups interconnected in a series circuit. A lens is included over the LED chips. Other embodiments can comprise thermal spreading structures included integral to the submount and arranged to dissipate heat from the LED chips.

  1. Solid state lighting component

    DOE Patents [OSTI]

    Keller, Bernd; Ibbetson, James; Tarsa, Eric; Negley, Gerald; Yuan, Thomas

    2012-07-10T23:59:59.000Z

    An LED component comprising an array of LED chips mounted on a planar surface of a submount with the LED chips capable of emitting light in response to an electrical signal. The LED chips comprise respective groups emitting at different colors of light, with each of the groups interconnected in a series circuit. A lens is included over the LED chips. Other embodiments can comprise thermal spreading structures included integral to the submount and arranged to dissipate heat from the LED chips.

  2. Thermal trim for a luminaire

    DOE Patents [OSTI]

    Bazydola, Sarah; Ghiu, Camil-Daniel; Harrison, Robert; Jeswani, Anil

    2013-02-19T23:59:59.000Z

    A luminaire with a thermal pathway to reduce the junction temperature of the luminaire's light source, and methods for so doing, are disclosed. The luminaire includes a can, a light engine, and a trim, that define a substantially continuous thermal pathway from the light engine to a surrounding environment. The can defines a can cavity and includes a can end region. The light engine is within the can cavity and includes a light source and a heat sink, including a heat sink end region, coupled thereto. The trim is at least partially disposed within the can cavity and includes a first trim end region coupled to the heat sink end region and a second trim end region coupled to the can end region. Thermal interface material may be located between: the heat sink and the trim, the trim and the can, and/or the heat sink and the light source.

  3. Lighting system with heat distribution face plate

    DOE Patents [OSTI]

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Li, Ri

    2013-09-10T23:59:59.000Z

    Lighting systems having a light source and a thermal management system are provided. The thermal management system includes synthetic jet devices, a heat sink and a heat distribution face plate. The synthetic jet devices are arranged in parallel to one and other and are configured to actively cool the lighting system. The heat distribution face plate is configured to radially transfer heat from the light source into the ambient air.

  4. Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

    SciTech Connect (OSTI)

    Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

    1995-07-01T23:59:59.000Z

    This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

  5. Long-lived guided phonons in fiber by manipulating two-level systems

    E-Print Network [OSTI]

    R. O. Behunin; P. Kharel; W. H. Renninger; H. Shin; F. Carter; E. Kittlaus; P. T. Rakich

    2015-01-23T23:59:59.000Z

    The synthesis of ultra-long lived acoustic phonons in a variety of materials and device geometries could enable a range of new coherent information processing and sensing technologies; many forms of phonon dissipation pose a barrier to this goal. We explore linear and nonlinear contributions to phonon dissipation in silica at cryogenic temperatures using fiber-optic structures that tightly confine both photons and phonons to the fiber-optic core. When immersed in helium, this fiber system supports nearly perfect guidance of 9 GHz acoustic phonons; strong electrostrictively mediated photon-phonon coupling (or guided-wave stimulated Brillouin scattering) permits a flexible form of laser-based phonon spectroscopy. Through linear and nonlinear phonon spectroscopy, we isolate the effects of disorder-induced two-level tunneling states as a source of phononic dissipation in this system. We show that an ensemble of such two-level tunneling states can be driven into transparency--virtually eliminating this source of phonon dissipation over a broad range of frequencies. Experimental studies of phononic self-frequency saturation show excellent agreement with a theoretical model accounting for the phonon coupling to an ensemble of two-level tunneling states. Extending these results, we demonstrate a general approach to suppress dissipation produced by two-level tunneling states via cross-saturation, where the lifetime of a phonons at one frequency can be extended by the presence of a high intensity acoustic beam at another frequency. Although these studies were carried out in silica, our findings are quite general, and can be applied to a range of materials systems and device geometries.

  6. Plasmon-phonon interactions in topological insulator rings

    E-Print Network [OSTI]

    Autore, Marta; Di Gaspare, Alessandra; Giliberti, Valeria; Limaj, Odeta; Roy, Pascale; Brahlek, Matthew; Koirala, Nikesh; Oh, Seongshik; de Abajo, Francisco Javier Garcìa; Lupi, Stefano

    2015-01-01T23:59:59.000Z

    The great potential of Dirac electrons for plasmonics and photonics has been readily recognized after their discovery in graphene, followed by applications to smart optical devices. Dirac carriers are also found in topological insulators (TI) --quantum systems having an insulating gap in the bulk and intrinsic Dirac metallic states at the surface--. Here, we investigate the plasmonic response of ring structures patterned in Bi$_2$Se$_3$ TI films, which we investigate through terahertz (THz) spectroscopy. The rings are observed to exhibit a bonding and an antibonding plasmon modes, which we tune in frequency by varying their diameter. We develop an analytical theory based on the THz conductivity of unpatterned films, which accurately describes the strong plasmon-phonon hybridization and Fano interference experimentally observed as the bonding plasmon is swiped across the promineng 2\\,THz phonon exhibited by this material. This work opens the road for the investigation of plasmons in topological insulators and ...

  7. Phonons in a one-dimensional microfluidic crystal

    E-Print Network [OSTI]

    Tsevi Beatus; Tsvi Tlusty; Roy Bar-Ziv

    2010-08-06T23:59:59.000Z

    The development of a general theoretical framework for describing the behaviour of a crystal driven far from equilibrium has proved difficult1. Microfluidic crystals, formed by the introduction of droplets of immiscible fluid into a liquid-filled channel, provide a convenient means to explore and develop models to describe non-equilibrium dynamics2, 3, 4, 5, 6, 7, 8, 9, 10, 11. Owing to the fact that these systems operate at low Reynolds number (Re), in which viscous dissipation of energy dominates inertial effects, vibrations are expected to be over-damped and contribute little to their dynamics12, 13, 14. Against such expectations, we report the emergence of collective normal vibrational modes (equivalent to acoustic 'phonons') in a one-dimensional microfluidic crystal of water-in-oil droplets at Reapprox10-4. These phonons propagate at an ultra-low sound velocity of approx100 mum s-1 and frequencies of a few hertz, exhibit unusual dispersion relations markedly different to those of harmonic crystals, and give rise to a variety of crystal instabilities that could have implications for the design of commercial microfluidic systems. First-principles theory shows that these phonons are an outcome of the symmetry-breaking flow field that induces long-range inter-droplet interactions, similar in nature to those observed in many other systems including dusty plasma crystals15, 16, vortices in superconductors17, 18, active membranes19 and nucleoprotein filaments20.

  8. Phonon lifetime in SiSn and its suitability for hot-carrier solar cells

    SciTech Connect (OSTI)

    Levard, Hugo; Laribi, Sana; Guillemoles, Jean-François [Institute for Research and Development on Photovoltaic Energy (IRDEP), UMR 7174, EDF R and D/CNRS/Chimie ParisTech, 6 quai Watier, 78401 Chatou (France)

    2014-06-02T23:59:59.000Z

    We present a phononic and electronic study of SiSn in the zinc-blende phase. A detailed description of the longitudinal optical (LO) phonon decay in a three-phonon process is presented together with the corresponding lifetime. The necessity to go beyond the zone center phonon approximation in this case is highlighted as it reveals a steep dependence of the lifetime on the initial phonon wavenumber, which differs from usual semiconductors. The electronic band structure is calculated within the GW formalism and shows a small direct band gap. It is shown that the LO-phonon resulting from electron cooling has a lifetime four to eight orders of magnitude above all the known value in semiconductors for this process. We finally show the suitability of SiSn for hot-carrier solar cells, as it is endowed with ultra-slow cooling of hot carriers.

  9. Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration

    E-Print Network [OSTI]

    Khurgin, Jacob B

    2014-01-01T23:59:59.000Z

    Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.

  10. Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration

    SciTech Connect (OSTI)

    Khurgin, Jacob B., E-mail: jakek@jhu.edu [Johns Hopkins University, Baltimore, Maryland 21208 (United States)

    2014-06-02T23:59:59.000Z

    Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work, we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.

  11. Nanoscale size dependence parameters on lattice thermal conductivity of Wurtzite GaN nanowires

    SciTech Connect (OSTI)

    Mamand, S.M., E-mail: soran.mamand@univsul.net [Department of Physics, College of Science, University of Sulaimani, Sulaimanyah, Iraqi Kurdistan (Iraq); Omar, M.S. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)] [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Muhammad, A.J. [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)] [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)

    2012-05-15T23:59:59.000Z

    Graphical abstract: Temperature dependence of calculated lattice thermal conductivity of Wurtzite GaN nanowires. Highlights: Black-Right-Pointing-Pointer A modified Callaway model is used to calculate lattice thermal conductivity of Wurtzite GaN nanowires. Black-Right-Pointing-Pointer A direct method is used to calculate phonon group velocity for these nanowires. Black-Right-Pointing-Pointer 3-Gruneisen parameter, surface roughness, and dislocations are successfully investigated. Black-Right-Pointing-Pointer Dislocation densities are decreases with the decrease of wires diameter. -- Abstract: A detailed calculation of lattice thermal conductivity of freestanding Wurtzite GaN nanowires with diameter ranging from 97 to 160 nm in the temperature range 2-300 K, was performed using a modified Callaway model. Both longitudinal and transverse modes are taken into account explicitly in the model. A method is used to calculate the Debye and phonon group velocities for different nanowire diameters from their related melting points. Effect of Gruneisen parameter, surface roughness, and dislocations as structure dependent parameters are successfully used to correlate the calculated values of lattice thermal conductivity to that of the experimentally measured curves. It was observed that Gruneisen parameter will decrease with decreasing nanowire diameters. Scattering of phonons is assumed to be by nanowire boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. Phonon confinement and size effects as well as the role of dislocation in limiting thermal conductivity are investigated. At high temperatures and for dislocation densities greater than 10{sup 14} m{sup -2} the lattice thermal conductivity would be limited by dislocation density, but for dislocation densities less than 10{sup 14} m{sup -2}, lattice thermal conductivity would be independent of that.

  12. Second Harmonic Generation and Confined Acoustic Phonons in Highly Excited Semiconductor Nanocrystals

    E-Print Network [OSTI]

    Son, Dong Hee; Wittenberg, Joshua S.; Banin, Uri; Alivisatos, A. Paul

    2006-01-01T23:59:59.000Z

    Second harmonic generation and confined acoustic phonons inenhancement of second harmonic generation, and the effect ofmeasurements. The second harmonic signal showed a sublinear

  13. Lattice NRQCD study of S- and P-wave bottomonium states in a thermal medium with $N_f=2+1$ light flavors

    E-Print Network [OSTI]

    Seyong Kim; Peter Petreczky; Alexander Rothkopf

    2014-09-12T23:59:59.000Z

    We investigate the properties of S-and P-wave bottomonium states in the vicinity of the deconfinement transition temperature. The light degrees of freedom are represented by dynamical lattice QCD configurations of the HotQCD collaboration with $N_f = 2 + 1$ flavors. Bottomonium correlators are obtained from bottom quark propagators, computed in Non-Relativistic QCD (NRQCD) under the background of these gauge field configurations. The spectral functions for the $^3S_1$ ($\\Upsilon$) and $^3P_1$ ($\\chi_{b1}$) channel are extracted from the Euclidean time correlators using a novel Bayesian approach in the temperature region $140 {\\rm MeV} \\le T \\le 249 {\\rm MeV}$ and the results are contrasted to those from the standard Maximum Entropy Method. We find that the new Bayesian approach is far superior to the Maximum Entropy Method and enables us to study reliably the first peak in the spectral functions even under the limitations present in the finite temperature setup. We find that $\\chi_{b1}$ survives up to $T=249 {\\rm MeV}$, the highest temperature considered in our study and put stringent constraints on the size of the medium modification of $\\Upsilon$ and $\\chi_{b1}$ states.

  14. A deviational Monte Carlo formulation of ab initio phonon transport and its application to the study of kinetic effects in graphene ribbons

    E-Print Network [OSTI]

    Landon, Colin Donald

    2014-01-01T23:59:59.000Z

    We present a deviational Monte Carlo method for solving the Boltzmann equation for phonon transport subject to the linearized ab initio 3-phonon scattering operator. Phonon dispersion relations and transition rates are ...

  15. Anisotropic surface phonon dispersion of the hydrogen-terminated Si(110)-(1×1) surface: One-dimensional phonons propagating along the glide planes

    SciTech Connect (OSTI)

    Matsushita, Stephane Yu; Matsui, Kazuki; Kato, Hiroki; Suto, Shozo, E-mail: suto@surface.phys.tohoku.ac.jp [Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan)] [Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Yamada, Taro [RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)] [RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)

    2014-03-14T23:59:59.000Z

    We have measured the surface phonon dispersion curves on the hydrogen-terminated Si(110)-(1×1) surface with the two-dimensional space group of p2mg along the two highly symmetric and rectangular directions of ?X{sup ¯} and ?X{sup ?¯} using high-resolution electron-energy-loss spectroscopy. All the essential energy-loss peaks on H:Si(110) were assigned to the vibrational phonon modes by using the selection rules of inelastic electron scattering including the glide-plane symmetry. Actually, the surface phonon modes of even-symmetry to the glide plane (along ?X{sup ¯}) were observed in the first Brillouin zone, and those of odd-symmetry to the glide plane were in the second Brillouin zone. The detailed assignment was made by referring to theoretical phonon dispersion curves of Gräschus et al. [Phys. Rev. B 56, 6482 (1997)]. We found that the H–Si stretching and bending modes, which exhibit highly anisotropic dispersion, propagate along ?X{sup ¯} direction as a one-dimensional phonon. Judging from the surface structure as well as our classical and quantum mechanical estimations, the H–Si stretching phonon propagates by a direct repulsive interaction between the nearest neighbor H atoms facing each other along ?X{sup ¯}, whereas the H–Si bending phonon propagates by indirect interaction through the substrate Si atomic linkage.

  16. Smart lighting: New Roles for Light

    E-Print Network [OSTI]

    Salama, Khaled

    Smart lighting: New Roles for Light in the Solid State Lighting World Robert F. Karlicek, Jr. Director, Smart Lighting Engineering Research Center Professor, Electrical, Systems and Computer Lighting · What is Smart Lighting · Technology Barriers to Smart Lighting · Visible Light Communications

  17. Commercial Lighting

    Broader source: Energy.gov [DOE]

    Commercial lighting accounts for more than 20 percent of total commercial building energy use. The Energy Department works to reduce lighting energy use through research and deployment.

  18. Lattice thermal conductivity of filled skutterudites: An anharmonicity perspective

    SciTech Connect (OSTI)

    Geng, Huiyuan, E-mail: genghuiyuan@hit.edu.cn; Meng, Xianfu; Zhang, Hao; Zhang, Jian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2014-10-28T23:59:59.000Z

    We report a phenomenological model to calculate the high-temperature lattice thermal conductivity of filled skutterudite antimonides. The model needs no phonon resonant scattering terms. Instead, we assume that umklapp processes dominate the high-temperature phonon scattering. In order to represent the anharmonicity introduced by the filling atom, we introduce a Gaussian term into the relaxation time of the umklapp process. The developed model agrees remarkably well with the experimental results of RE{sub f}Co{sub 4}Sb{sub 12} and RE{sub f}Fe{sub 4}Sb{sub 12} (RE?=?Yb, Ba, and Ca) alloys. To further test the validity of our model, we calculate the lattice thermal conductivity of nanostructured or multi-filled skutterudites. The calculation results are also in good agreement with experiment, increasing our confidence in the developed anharmonicity model.

  19. Novel applications exploiting the thermal properties of nanostructured materials.

    SciTech Connect (OSTI)

    Eastman, J. A.

    1998-11-20T23:59:59.000Z

    A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers.

  20. Coupled vibrational modes in multiple-filled skutterudites and the effects on lattice thermal conductivity reduction

    E-Print Network [OSTI]

    Xu, Xianfan

    of studies including Raman spectroscopy,9 inelastic neutron scattering, heat capacity measurements,10, which scatter phonons in different spectral spans. Using a Debye model for the measured lattice thermal conductivity together with the measured vibration frequencies and scattering rates, it is shown that scattering

  1. Proceedings of HT2007 2007 ASME-JSME Thermal Engineering Summer Heat Transfer Conference

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Proceedings of HT2007 2007 ASME-JSME Thermal Engineering Summer Heat Transfer Conference July 8-BALLISTIC PHONON TRANSPORT IN A CARBON NANOTUBE Junichiro Shiomi Department of Mechanical Engineering Engineering The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan ABSTRACT We report a non

  2. Electro-thermal Simulations of Strained-Si MOSFETs under ESD conditions

    E-Print Network [OSTI]

    Dutton, Robert W.

    that of bulk-Si [1,2]) causes severe self-heating, considerably changing some electrical properties. Especially the phonon mean-free-path of strained-Si with high electric fields was estimated based on a full of strained-Si is of technological importance. In this work, electrical and thermal characteristics

  3. Hybrid Surface-Phonon-Plasmon Polariton Modes in Graphene/ Monolayer hBN Heterostructures

    E-Print Network [OSTI]

    Atwater, Harry

    Hybrid Surface-Phonon-Plasmon Polariton Modes in Graphene/ Monolayer hBN Heterostructures Victor W reveal the hybridization of graphene plasmons and the phonons in a monolayer hexagonal boron nitride (h-BN) sheet. Frequency- wavevector dispersion relations of the electromagnetically coupled graphene plasmon

  4. Effect of temperature on phonon contribution to Green function of high-temperature superconducting cuprates

    SciTech Connect (OSTI)

    Korneeva, L. A., E-mail: korneeva_mila@mail.ru; Mazur, E. A. [National Research Nuclear University MEPhI (Russian Federation)

    2012-08-15T23:59:59.000Z

    The phonon contribution to the nodal electron Green function in cuprates is considered. It is shown that the temperature dependence of the real part of the self-energy component of the Green function for cuprates with a hole doping level close to optimal is described by the electron-phonon interaction in the framework of the extended Eliashberg model.

  5. Breathing coherent phonons and caps fragmentation in carbon nanotubes following ultrafast laser pulses

    E-Print Network [OSTI]

    Dumitrica,Traian

    driven by ultrafast laser pulses.1­3 The necessary conditions for generating such coherent phonons are i is larger than the duration of currently available ultrafast pulses. ii Measurements4­7 determinedBreathing coherent phonons and caps fragmentation in carbon nanotubes following ultrafast laser

  6. Effect of a magnetic field on the two-phonon Raman scattering in C. Faugeras,1

    E-Print Network [OSTI]

    Boyer, Edmond

    Effect of a magnetic field on the two-phonon Raman scattering in graphene C. Faugeras,1 P. Kossacki spectrum of graphene (the two-phonon peak near 2700 cm-1) in an external magnetic field applied perpendicular to the graphene crystal plane at liquid helium temperature. A shift to lower frequency

  7. Anomalous Microfluidic Phonons Induced by the Interplay of Hydrodynamic Screening and Incompressibility

    E-Print Network [OSTI]

    Tlusty, Tsvi

    Anomalous Microfluidic Phonons Induced by the Interplay of Hydrodynamic Screening the acoustic normal modes (``phonons'') of a 1D microfluidic droplet crystal at the crossover between 2D flow.55.Dÿ, 47.60.+i, 47.63.mf, 63.22.+m Microfluidic two-phase flow offers experimental tools to investigate

  8. Exciton-Phonon coupling in the finite temperature optical absorption of

    E-Print Network [OSTI]

    Marini, Andrea

    and absorption spectra PRL 95, 247401 (2005) PRB 36, 4821 (1987) Phonons are responsible for the temperature temperature optics in the polaronic approximation A phononic self-energy for the exciton #12;PRB 23, 1495 (1981)LH and SL, Solid. State Phys. 23, 1 (1969); RvL, PRB 69, 115110 (2004) I Is Cardona-Allen further

  9. A first principles pseudopotential in the calculation of the phonon limited resistivity of sodium and potassium

    E-Print Network [OSTI]

    Boyer, Edmond

    of properties of aluminum and lithium. It is obtained from the induced electron density around an ion propriétés de l'aluminium et du lithium. Il s'obtient à partir de la densité électronique induite autour d potential and from this, the phonons to calculate the electron-phonon interaction to predict the resistivity

  10. Raman spectra of out-of-plane phonons in bilayer graphene

    E-Print Network [OSTI]

    Sato, Kentaro

    The double resonance Raman spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of ...

  11. On the Existence of an Independent Phonon Bath in a Quantum Device L. M. A. Pascal,1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    other by a 40 nm thick layer of Si. (c) Heat transfer model. Electrons and phonons of the bottom (top

  12. Modification of phonon processes in nano-structured rare-earth-ion-doped crystals

    E-Print Network [OSTI]

    Lutz, Thomas; Thiel, Charles W; Cone, Rufus L; Barclay, Paul E; Tittel, Wolfgang

    2015-01-01T23:59:59.000Z

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable, or improve, persistent spectral hole-burning and optical coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

  13. Lattice thermal conductivity of UO{sub 2} using ab-initio and classical molecular dynamics

    SciTech Connect (OSTI)

    Kim, Hyoungchul [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136–791 (Korea, Republic of); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kaviany, Massoud, E-mail: kaviany@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-28T23:59:59.000Z

    We applied the non-equilibrium ab-initio molecular dynamics and predict the lattice thermal conductivity of the pristine uranium dioxide for up to 2000?K. We also use the equilibrium classical molecular dynamics and heat-current autocorrelation decay theory to decompose the lattice thermal conductivity into acoustic and optical components. The predicted optical phonon transport is temperature independent and small, while the acoustic component follows the Slack relation and is in good agreement with the limited single-crystal experimental results. Considering the phonon grain-boundary and pore scatterings, the effective lattice thermal conductivity is reduced, and we show it is in general agreement with the sintered-powder experimental results. The charge and photon thermal conductivities are also addressed, and we find small roles for electron, surface polaron, and photon in the defect-free structures and for temperatures below 1500?K.

  14. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO{sub 2}

    SciTech Connect (OSTI)

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Ohodnicki, Andio, Mark; Lewis, James; P Matranga, Christopher

    2013-05-01T23:59:59.000Z

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO{sub 2} and H{sub 2} reactants to CH{sub 4} and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to #1;~600 {degrees}#3;C and simultaneously tune the CH{sub 4} : CO product ratio. The laser induced heating and resulting CH{sub 4} : CO product distribution agrees well with predictions from thermodynamic models and temperatureprogrammed reaction experiments indicating that the reaction is a thermally driven process resulting from the plasmonic heating of the Au–ZnO. The apparent quantum yield for CO{sub 2} conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au–ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO{sub 2} reduction is low (#1;~2.5 x#4; 10{sup 5} W m{sup #5;-2}) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO{sub 2} utilization and other practical thermal catalytic applications.

  15. Nonadiabatic phonons within the doped graphene layers of XC6 compounds Mark P. M. Dean,1,* Christopher A. Howard,2 Siddharth S. Saxena,1 and Mark Ellerby2

    E-Print Network [OSTI]

    Sheldon, Nathan D.

    Nonadiabatic phonons within the doped graphene layers of XC6 compounds Mark P. M. Dean,1 a systematic study of the phonons and the electron-phonon interaction within the doped graphene layers of these compounds. The out-of-plane carbon phonon softens as the spacing of the graphene layers is reduced

  16. Light Properties Light travels at the speed of light `c'

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    LIGHT!! #12;Light Properties Light travels at the speed of light `c' C = 3 x 108 m/s Or 190,000 miles/second!! Light could travel around the world about 8 times in one second #12;What is light?? Light is a "wave packet" A photon is a "light particle" #12;Electromagnetic Radiation and You Light is sometimes

  17. Phonon-Polaritons enhance near field thermal transfer across the phase transition of VO2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    of temperature is of great importance in many areas in physics and chemistry. Pioneering work has led to heat modulators with low cooling power [11], or as concepts [12]. They employ either solid-fluids mechanisms

  18. Ballistic Phonon Thermal Transport in Multiwalled Carbon Nanotubes H.-Y. Chiu,1

    E-Print Network [OSTI]

    Bockrath, Marc

    coupled with the electrical stress of carrying 1012 A=m2 . We also demonstrate a current-driven self-heating electrical transport experiments, using the phenomenon of electrical breakdown to perform thermometry experiments, we heat multiwalled nanotubes (MWNTs) with an electrical current and monitor tempera- ture

  19. Phonon and thermal properties of exfoliated TaSe2 thin films T. R. Pope,2

    E-Print Network [OSTI]

    films exfoliated from TaSe2 and other metal dichalcogenides, as well as for evaluating self-heating-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California its bulk value of $16 W/mK to $9 W/mK in 45-nm thick films. The measurement of electrical resistivity

  20. Piezoelectric surface acoustical phonon amplification in graphene on a GaAs substrate

    SciTech Connect (OSTI)

    Nunes, O. A. C., E-mail: oacn@unb.br [Institute of Physics, University of Brasilia, Brasilia, 70910-900 DF (Brazil)

    2014-06-21T23:59:59.000Z

    We study the interaction of Dirac Fermions in monolayer graphene on a GaAs substrate in an applied electric field by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (piezoelectric acoustical (PA)) and of the intrinsic deformation potential of acoustical phonons in graphene (deformation acoustical (DA)). We find that provided the dc field exceeds a threshold value, emission of piezoelectric (PA) and deformation (DA) acoustical phonons can be obtained in a wide frequency range up to terahertz at low and high temperatures. We found that the phonon amplification rate R{sup PA,DA} scales with T{sub BG}{sup S?1} (S=PA,DA), T{sub BG}{sup S} being the Block?Gru{sup ¨}neisen temperature. In the high-T Block?Gru{sup ¨}neisen regime, extrinsic PA phonon scattering is suppressed by intrinsic DA phonon scattering, where the ratio R{sup PA}/R{sup DA} scales with ?1/?(n), n being the carrier concentration. We found that only for carrier concentration n?10{sup 10}cm{sup ?2}, R{sup PA}/R{sup DA}>1. In the low-T Block?Gru{sup ¨}neisen regime, and for n=10{sup 10}cm{sup ?2}, the ratio R{sup PA}/R{sup DA} scales with T{sub BG}{sup DA}/T{sub BG}{sup PA}?7.5 and R{sup PA}/R{sup DA}>1. In this regime, PA phonon dominates the electron scattering and R{sup PA}/R{sup DA}<1 otherwise. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as an acoustical phonon amplifier and a frequency-tunable acoustical phonon device.

  1. Phonon densities of states of face-centered-cubic Ni-Fe alloys

    SciTech Connect (OSTI)

    Lucas, Matthew [United States Air Force Research Laboratory, Wright-Patterson Air Force Base] [United States Air Force Research Laboratory, Wright-Patterson Air Force Base; Mauger, L [California Institute of Technology, W. M. Keck Laboratory, Pasadena] [California Institute of Technology, W. M. Keck Laboratory, Pasadena; Munoz, Jorge A. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Halevy, I [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Horwath, J [United States Air Force Research Laboratory, Wright-Patterson Air Force Base] [United States Air Force Research Laboratory, Wright-Patterson Air Force Base; Semiatin, S L [United States Air Force Research Laboratory, Wright-Patterson Air Force Base] [United States Air Force Research Laboratory, Wright-Patterson Air Force Base; Leontsev, S. O. [University of Kentucky, Lexington] [University of Kentucky, Lexington; Stone, Matthew B [ORNL] [ORNL; Abernathy, Douglas L [ORNL] [ORNL; Xiao, Yuming [Carnegie Institution of Washington] [Carnegie Institution of Washington; Chow, P [HPCAT Geophysical Lab, Argonne, IL] [HPCAT Geophysical Lab, Argonne, IL; Fultz, B. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena

    2013-01-01T23:59:59.000Z

    Inelastic neutron scattering and nuclear resonant inelastic x-ray scattering were used to determine the phonon densities of states of face-centered-cubic Ni-Fe alloys. Increasing Fe concentration results in an average softening of the phonon modes. Chemical ordering of the Ni0.72Fe0.28 alloy results in a reduction of the partial vibrational entropy of the Fe atoms but does not significantly change the partial vibrational entropy of the Ni atoms. Changes in the phonon densities of states with composition and chemical ordering are discussed and analyzed with a cluster expansion method.

  2. Phonon blocking by two dimensional electron gas in polar CdTe/PbTe heterojunctions

    SciTech Connect (OSTI)

    Zhang, Bingpo; Cai, Chunfeng; Zhu, He; Wu, Feifei; Ye, Zhenyu; Chen, Yongyue; Li, Ruifeng; Kong, Weiguang; Wu, Huizhen, E-mail: hzwu@zju.edu.cn [Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-04-21T23:59:59.000Z

    Narrow-gap lead telluride crystal is an important thermoelectric and mid-infrared material in which phonon functionality is a critical issue to be explored. In this Letter, efficient phonon blockage by forming a polar CdTe/PbTe heterojunction is explicitly observed by Raman scattering. The unique phonon screening effect can be interpreted by recent discovery of high-density two dimensional electrons at the polar CdTe/PbTe(111) interface which paves a way for design and fabrication of thermoelectric devices.

  3. Contribution of the electron-phonon coupling to Lindhard partition at low energy in Ge and Si detectors for astroparticle physics

    E-Print Network [OSTI]

    Lazanu, Ionel

    2015-01-01T23:59:59.000Z

    The influence of the transient thermal effects on the partition of the energy of selfrecoils in germanium and silicon into energy eventually given to electrons and to atomic recoils respectively is studied. The transient effects are treated in the frame of the thermal spike model, which considers the electronic and atomic subsystems coupled through the electron-phonon interaction. For low energies of selfrecoils, we show that the corrections to the energy partition curves due to the energy exchange during the transient processes modify the Lindhard predictions. These effects depend on the initial temperature of the target material, as the energies exchanged between electronic and lattice subsystems have different signs for temperatures lower and higher than about 15 K. More of the experimental data reported in the literature support the model.

  4. Smart Lighting Controller!! Smart lighting!

    E-Print Network [OSTI]

    Anderson, Betty Lise

    1! Smart Lighting Controller!! #12;2! Smart lighting! No need to spend energy lighting the room if://blogs.stthomas.edu/realestate/2011/01/24/residential-real-estate-professionals-how-do-you- develop feedback! There is a connection between the output and the input! Therefore forces inputs to same voltage

  5. Thermal transport of the single-crystal rare-earth nickel borocarbides RNi2B2C

    E-Print Network [OSTI]

    Hennings, BD; Naugle, Donald G.; Canfield, PC.

    2002-01-01T23:59:59.000Z

    superconductivity in this material above T-N. Unlike the case for the non-magnetic superconductors in the family, R=Y and Lu, a phonon peak in the thermal conductivity below T-c is not observed down to T=1.4 K for the magnetic superconductors. Single-crystal quality...

  6. Integrated LED-based luminare for general lighting

    DOE Patents [OSTI]

    Dowling, Kevin J.; Lys, Ihor A.; Roberge, Brian; Williamson, Ryan C.; Roberts, Ron; Datta, Michael; Mollnow, Tomas; Morgan, Frederick M.

    2013-03-05T23:59:59.000Z

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  7. Study on generating of thermal neutron scattering cross sections for LiH

    SciTech Connect (OSTI)

    Wang, L.; Jiang, X.; Zhao, Z.; Chen, L. [Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2013-07-01T23:59:59.000Z

    LiH is designated as a promising moderator and shielding material because of its low density, high melting point and large fraction of H atoms. However, lack of the thermal neutron cross sections of LiH makes numerical calculation deviate from experimental data to some extent. As a result, it is necessary to study LiH thermal kernel effect. The phonon property of LiH has been investigated by first-principles calculations using the plane-wave pseudo potential method with CASTEP code. The scattering law and the thermal neutron scattering cross sections for Li and H have been generated using this distribution. The results have been compared with zirconium hydride data. The GASKET and NJOY/LEAPR codes have been used in the calculation of scattering law, whose results have been compared with the reference; the discrepancy mainly comes from phonon spectrums and its expansion. LEAPR had the capability to compute scattering through larger energy and momentum transfers than GASKET did. By studying LiH phonon spectrum and constructing the model of LiH thermal kernel and scattering matrix, the ACE format LiH thermal neutron cross sections for MCNP software could be made and used for reactor Neutronics calculation. (authors)

  8. Sandia National Laboratories: metal hydride storage thermal-management...

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

    thermal-management issues ECIS, Boeing, Caltrans, and Others: Fuel-Cell-Powered Mobile Lighting Applications On March 29, 2013, in Capabilities, CRF, Energy, Energy Efficiency,...

  9. Effects of Electron-Phonon Coupling in Single-Molecule Magnet...

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

    Electron-Phonon Coupling in Single-Molecule Magnet Transport Junctions Using a Hybrid Density Functional Theory and Model Hamiltonian Approach Apr 04 2014 10:00 AM - 11:00 AM Alex...

  10. Phonon counting and intensity interferometry of a nanomechanical resonator Justin D. Cohen,1,

    E-Print Network [OSTI]

    Painter, Oskar

    these measurements in a Hanbury Brown and Twiss set-up, phonon correlations of the nanomechanical resonator- try performed by Hanbury Brown and Twiss (HBT) [3] to measure the angular width of visible stars, have

  11. Phonon laser action in a tunable, two-level photonic molecule

    E-Print Network [OSTI]

    Ivan S. Grudinin; O. Painter; Kerry J. Vahala

    2009-07-29T23:59:59.000Z

    The phonon analog of an optical laser has long been a subject of interest. We demonstrate a compound microcavity system, coupled to a radio-frequency mechanical mode, that operates in close analogy to a two-level laser system. An inversion produces gain, causing phonon laser action above a pump power threshold of around 50 $\\mu$W. The device features a continuously tunable, gain spectrum to selectively amplify mechanical modes from radio frequency to microwave rates. Viewed as a Brillouin process, the system accesses a regime in which the phonon plays what has traditionally been the role of the Stokes wave. For this reason, it should also be possible to controllably switch between phonon and photon laser regimes. Cooling of the mechanical mode is also possible.

  12. Influence of electron–phonon interactions in single dopant nanowire transistors

    SciTech Connect (OSTI)

    Carrillo-Nuñez, H., E-mail: carrillh@iis.ee.ethz.ch; Bescond, M., E-mail: marc.bescond@im2np.fr; Cavassilas, N.; Dib, E.; Lannoo, M. [IM2NP, UMR CNRS 6242, Bât. IRPHE, Technopôle de Château-Gombert, 13384 Marseille, Cedex 13 (France)

    2014-10-28T23:59:59.000Z

    Single dopant nanowire transistors can be viewed as the ultimate miniaturization of nano electronic devices. In this work, we theoretically investigate the influence of the electron-phonon coupling on their transport properties using a non-equilibrium Green's function approach in the self-consistent Born approximation. For an impurity located at the center of the wire we find that, at room temperature, acoustic phonons broaden the impurity level so that the bistability predicted in the ballistic regime is suppressed. Optical phonons are found to have a beneficial impact on carrier transport via a phonon-assisted tunneling effect. We discuss the position and temperature dependence of these effects, showing that such systems might be very promising for engineering of ultimate devices.

  13. Effects of ternary mixed crystal and size on optical phonons in wurtzite nitride core-shell nanowires

    SciTech Connect (OSTI)

    Li, J.; Guan, J. Y.; Zhang, S. F.; Ban, S. L.; Qu, Y., E-mail: quyuan@imu.edu.cn [School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China)

    2014-04-21T23:59:59.000Z

    Within the framework of dielectric continuum and Loudon's uniaxial crystal models, existence conditions dependent on components and frequencies for optical phonons in wurtzite nitride core-shell nanowires (CSNWs) are discussed to obtain dispersion relations and electrostatic potentials of optical phonons in In{sub x}Ga{sub 1?x}N/GaN CSNWs. The results show that there may be four types of optical phonons in In{sub x}Ga{sub 1?x}N/GaN CSNWs for a given ternary mixed crystal (TMC) component due to the phonon dispersion anisotropy. This property is analogous to wurtzite planar heterojunctions. Among the optical phonons, there are two types of quasi-confined optical (QCO) phonons (named, respectively, as QCO-A and QCO-B), one type of interface (IF) phonons and propagating (PR) phonons existing in certain component and frequency domains while the dispersion relations and electrostatic potentials of same type of optical phonons vary with components. Furthermore, the size effect on optical phonons in CSNWs is also discussed. The dispersion relations of IF and QCO-A are independent of the boundary location of CSNWs. Meanwhile, dispersion relations and electrostatic potentials of QCO-B and PR phonons vary obviously with size, especially, when the ratio of a core radius to a shell radius is small, and dispersion relation curves of PR phonons appear to be close to each other, whereas, this phenomenon disappears when the ratio becomes large. Based on our conclusions, one can further discuss photoelectric properties in nitride CSNWs consisting of TMCs associated with optical phonons.

  14. Parity conservation in electron-phonon scattering in zigzag graphene nanoribbon

    SciTech Connect (OSTI)

    Chu, Yanbiao; Gautreau, Pierre; Basaran, Cemal, E-mail: cjb@buffalo.edu [Electronic Packaging Laboratory, University at Buffalo, SUNY, Buffalo, New York 14260 (United States)

    2014-09-15T23:59:59.000Z

    In contrast with carbon nanotubes, the absence of translational symmetry (or periodical boundary condition) in the restricted direction of zigzag graphene nanoribbon removes the selection rule of subband number conservation. However, zigzag graphene nanoribbons with even dimers do have the inversion symmetry. We, therefore, propose a selection rule of parity conservation for electron-phonon interactions. The electron-phonon scattering matrix in zigzag graphene nanoribbons is developed using the tight-binging model within the deformation potential approximation.

  15. Cerenkov Light

    ScienceCinema (OSTI)

    Slifer, Karl

    2014-05-22T23:59:59.000Z

    The bright blue glow from nuclear reactors is Cerenkov light. Karl Slifer describes how nuclear physicists can use this phenomenon to study the nucleus of the atom.

  16. Cerenkov Light

    SciTech Connect (OSTI)

    Slifer, Karl

    2013-06-13T23:59:59.000Z

    The bright blue glow from nuclear reactors is Cerenkov light. Karl Slifer describes how nuclear physicists can use this phenomenon to study the nucleus of the atom.

  17. Lighting Renovations

    Broader source: Energy.gov [DOE]

    When undertaking a lighting renovation in a Federal building, daylighting is the primary renewable energy opportunity. Photovoltaics (PV) also present an excellent opportunity. While this guide...

  18. Reexamination of Basal Plane Thermal Conductivity of Suspended Graphene Samples Measured by Electro-Thermal Micro-Bridge Methods

    SciTech Connect (OSTI)

    Jo, Insun [University of Texas at Austin; Pettes, Michael [University of Connecticut, Storrs; Lindsay, Lucas R [ORNL; Ou, Eric [University of Texas at Austin; Weathers, Annie [University of Texas at Austin; Moore, Arden [Louisiana Tech University; Yao, Zhen [University of Texas at Austin; Shi, Li [University of Texas at Austin

    2015-01-01T23:59:59.000Z

    Thermal transport in suspended graphene samples has been measured in prior works and this work with the use of a suspended electro-thermal micro-bridge method. These measurement results are analyzed here to evaluate and eliminate the errors caused by the extrinsic thermal contact resistance. It is noted that the thermal resistance measured in a recent work increases linearly with the suspended length of the single-layer graphene samples synthesized by chemical vapor deposition (CVD), and that such a feature does not reveal the failure of Fourier s law despite the increase in the apparent thermal conductivity with length. The re-analyzed thermal conductivity of a single-layer CVD graphene sample reaches about ( 1680 180 )Wm-1K-1 at room temperature, which is close to the highest value reported for highly oriented pyrolytic graphite. In comparison, the thermal conductivity values measured for two suspended exfoliated bi-layer graphene samples are about ( 880 60 ) and ( 730 60 ) Wm-1K-1 at room temperature, and approach that of the natural graphite source above room temperature. However, the low-temperature thermal conductivities of these suspended graphene samples are still considerably lower than the graphite values, with the peak thermal conductivities shifted to much higher temperatures. Analysis of the thermal conductivity data reveals that the low temperature behavior is dominated by phonon scattering by polymer residue instead of by the lateral boundary.

  19. Nanostructures and alloys : multiple scattering and nonlinearities in phonon transport

    E-Print Network [OSTI]

    Mendoza, Jonathan Michael

    2014-01-01T23:59:59.000Z

    Understanding how thermal transport is affected by disorder is crucial to the prediction and engineering of novel materials suitable for thermoelectric and device applications. Ab initio methods have demonstrated accurate ...

  20. The role of screening of the electron-phonon interaction in relaxation of photoexcited electron-hole plasma in semiconductors

    SciTech Connect (OSTI)

    Kumekov, S. E. [Kazakh National Technical University (Kazakhstan)], E-mail: skumekov@mail.ru

    2008-08-15T23:59:59.000Z

    The role of screening of the interaction of the electron-hole plasma with optical phonons is analytically evaluated by the example of gallium arsenide.

  1. Novel thermal properties of nanostructured materials.

    SciTech Connect (OSTI)

    Eastman, J. A.

    1999-01-13T23:59:59.000Z

    A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. For example, an approximately 20% improvement in effective thermal conductivity is observed when 5 vol.% CuO nanoparticles are added to water. Even more importantly, the heat transfer coefficient of water under dynamic flow conditions is increased more than 15% with the addition of less than 1 vol.% CuO particles. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers. Yttria-stabilized zirconia (YSZ) thin films are being produced by metal-organic chemical vapor deposition techniques. Preliminary results have indicated that the thermal conductivity is reduced by approximately a factor-of-two at room temperature in 10 nm grain-sized YSZ compared to coarse-grained or single crystal YSZ.

  2. Thermal Processes

    Broader source: Energy.gov [DOE]

    Some thermal processes use the energy in various resources, such as natural gas, coal, or biomass, to release hydrogen, which is part of their molecular structure. In other processes, heat, in...

  3. Net electron-phonon scattering rates in InN/GaN multiple quantum wells: The effects of an energy dependent acoustic deformation potential

    SciTech Connect (OSTI)

    Xia, H., E-mail: h.xia@unsw.edu.au; Patterson, R.; Feng, Y.; Shrestha, S.; Conibeer, G. [School of Photovoltaics and Renewable Energy Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia)

    2014-08-11T23:59:59.000Z

    The rates of charge carrier relaxation by phonon emission are of substantial importance in the field of hot carrier solar cell, primarily in investigation of mechanisms to slow down hot carrier cooling. In this work, energy and momentum resolved deformation potentials relevant to electron-phonon scattering are computed for wurtzite InN and GaN as well as an InN/GaN multiple quantum well (MQW) superlattice using ab-initio methods. These deformation potentials reveal important features such as discontinuities across the electronic bandgap of the materials and variations over tens of eV. The energy dependence of the deformation potential is found to be very similar for wurtzite nitrides despite differences between the In and Ga pseudopotentials and their corresponding electronic band structures. Charge carrier relaxation by this mechanism is expected to be minimal for electrons within a few eV of the conduction band edge. However, hole scattering at energies more accessible to excitation by solar radiation is possible between heavy and light hole states. Moderate reductions in overall scattering rates are observed in MQW relative to the bulk nitride materials.

  4. Coherent phonons in Si/SiGe superlattices Y. Ezzahri,* S. Grauby, J. M. Rampnoux, H. Michel, G. Pernot, W. Claeys, and S. Dilhaire

    E-Print Network [OSTI]

    Coherent phonons in Si/SiGe superlattices Y. Ezzahri,* S. Grauby, J. M. Rampnoux, H. Michel, G longitudinal-acoustic-phonon Bragg reflection. All of these are investigated in Si/SiGe superlattices using

  5. Interaction of Flexural Phonons with Electrons in Graphene: A Generalized Dirac Equation in Corrugated Surfaces

    E-Print Network [OSTI]

    Richard Kerner; Gerardo Naumis

    2011-02-10T23:59:59.000Z

    A generalized Dirac equation is derived in order to describe charge carriers moving in corrugated graphene, which is the case for temperatures above 10{\\deg}K due to the presence of flexural phonons. Such interaction is taken into account by considering an induced metric, in the same spirit as the general relativity approach for the description of fermionic particle moving in a curved space-time. The resulting equation allows to include in a natural way the presence of other phonon branches as well as an external electromagnetic field. It also predicts non-linear effects which are not present in the usual vector potential approximation used in most of publications on the subject, as well as the possibility of controlling electronic conductivity using pure sinusoidal strain fields. The non-linear terms are important at high temperatures, and can also lead to interesting effects, like e.g. resonances between flexural phonons and external electromagnetic fields.

  6. Phonon deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent Raman measurements

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonon deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent Raman measurements G online 9 February 2011 We report the phonon deformation potentials of wurtzite GaN and ZnO for all zone

  7. Strong Suppression of Electronic Coherence Time by Flexural Phonons in Graphene --- Example of a New Dephasing Mechanism 

    E-Print Network [OSTI]

    Zhao, Wei

    2014-07-08T23:59:59.000Z

    We investigate decoherence of an electron in graphene caused by electron-flexural phonon interaction.We find out that the flexural phonons can produce dephasing rate comparable to the electron-electron one. The problem appears to be quite special...

  8. Strong Suppression of Electronic Coherence Time by Flexural Phonons in Graphene --- Example of a New Dephasing Mechanism

    E-Print Network [OSTI]

    Zhao, Wei

    2014-07-08T23:59:59.000Z

    We investigate decoherence of an electron in graphene caused by electron-flexural phonon interaction.We find out that the flexural phonons can produce dephasing rate comparable to the electron-electron one. The problem appears to be quite special...

  9. PHYSICAL REVIEW B 86, 045413 (2012) Cooling of photoexcited carriers in graphene by internal and substrate phonons

    E-Print Network [OSTI]

    Perebeinos, Vasili

    for cooling of photoexcited carriers in graphene via the remote surface polar phonon modes (SPPPHYSICAL REVIEW B 86, 045413 (2012) Cooling of photoexcited carriers in graphene by internal through coupling to both intrinsic and remote (substrate) surface polar phonons using the Boltzmann

  10. Lattice thermal conductivity of nanograined half-Heusler solid solutions

    SciTech Connect (OSTI)

    Geng, Huiyuan, E-mail: genghuiyuan@hit.edu.cn; Meng, Xianfu; Zhang, Hao; Zhang, Jian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2014-05-19T23:59:59.000Z

    We report a phenomenological model of atomic weight, lattice constant, temperature, and grain size to calculate the high-temperature lattice thermal conductivity of nanograined solid solutions. The theoretical treatment developed here is reasonably consistent with the experimental results of n-type MNiSn and p-type MCoSb alloys, where M is the combination of Hf, Zr, and Ti. For disordered half-Heusler alloys with moderated grain sizes, we predict that the reduction in lattice thermal conductivity due to grain boundary scattering is independent of the scattering parameter, which characterizes the phonon scattering cross section of point defects. In addition, the lattice thermal conductivity falls off with temperature as T{sup –1?2} around the Debye temperature.

  11. Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

    DOE Patents [OSTI]

    Frei, Heinz (Berkeley, CA); Blatter, Fritz (Basel, CH); Sun, Hai (Saint Charles, MO)

    1999-01-01T23:59:59.000Z

    A process for selective thermal oxidation or photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts.

  12. Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

    DOE Patents [OSTI]

    Frei, Heinz (Berkeley, CA); Blatter, Fritz (Basel, CH); Sun, Hai (Saint Charles, MO)

    2001-01-01T23:59:59.000Z

    A process for a combined selective thermal oxidation and photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly combined selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts.

  13. Selective thermal and photooxidation of hydrocarbons in zeolites by oxygen

    DOE Patents [OSTI]

    Frei, H.; Blatter, F.; Sun, H.

    1999-06-22T23:59:59.000Z

    A process is described for selective thermal oxidation or photooxidation of hydrocarbons adsorbed onto zeolite matrices. A highly selective thermal oxidation and photooxidation of unsubstituted or alkyl substituted alkanes, alkenes, aromatics and cycloalkyls in solvent free zeolites under dark thermal conditions or under irradiation with visible light. The process oxidizes hydrocarbons almost completely selectively without substantial production of byproducts. 19 figs.

  14. Effect of electron-phonon interaction on resistivity of some heavy fermion (HF) systems

    SciTech Connect (OSTI)

    Sahoo, J., E-mail: jitendrasahoo2008@gmail.com [Assistant Director, Regional Office of Vocational Education, Sambalpur, Odisha-768004 (India); Shadangi, N. [Dept. of Physics, Silicon Institute of Technology, Sambalpur, Odisha-768200 (India); Nayak, P. [School of Physics, Sambalpur University, Sambalpur, Odisha-768019 (India)

    2014-04-24T23:59:59.000Z

    Here, we have analyzed the electron-phonon interaction in the Periodic Anderson Model (PAM) to describe the temperature dependence of resistivity in some heavy fermion (HF) systems for finite wave vector (q) and for finite temperature (T). Since the resistivity is related to the imaginary part of the electron self energy, the expression for the same is evaluated through double time temperature dependant Green function technique of the Zubarev type. The effect of different system parameters namely the position of 4f level, E{sub 0} and the electron - phonon coupling strengths on resistivity have been studied. The results obtained give satisfactory explanations to the experimental observations.

  15. Electromagnetically induced transparency from two-phonon processes in quadratically coupled membranes

    SciTech Connect (OSTI)

    Huang, Sumei; Agarwal, G. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

    2011-02-15T23:59:59.000Z

    We describe how electromagnetically induced transparency can arise in quadratically coupled optomechanical systems. Due to quadratic coupling, the underlying optical process involves a two-phonon process in an optomechanical system, and this two-phonon process makes the mean displacement, which plays the role of atomic coherence in traditional electromagnetically induced transparency (EIT), zero. We show how the fluctuation in displacement can play a role similar to atomic coherence and can lead to EIT-like effects in quadratically coupled optomechanical systems. We show how such effects can be studied using the existing optomechanical systems.

  16. A planar force-constant model for phonons in wurtzite GaN and AlN: Application to hexagonal GaN/AlN superlattices

    E-Print Network [OSTI]

    Lingjun Wang; Guanghong Wei; Jian Zi

    1998-12-17T23:59:59.000Z

    A planar force-constant model is developed for longitudinal phonons of wurtzite GaN and AlN propagating along the [0001] direction. The proposed model is then applied to the study of the phonon modes in hexagonal GaN/AlN superlattices in the longitudinal polarization. The confinement of the superlattice phonon mode is discussed.

  17. JOURNAL DE PHYSIQUE Colloque C4, supplkment au no 10, Octobre 1972, page C4-119 HEAT PULSE INTERACTION

    E-Print Network [OSTI]

    Boyer, Edmond

    made of the 3 phonon normal process scattering rate in dielectric solids from thermal conductivity data between available phonon states in a three vap = Q(ua,p- ~p,a)- (6) phonon normal process and is Article floride is considered in the light of these results. Introduction. - Several measurements [I] have been

  18. Light Computing

    E-Print Network [OSTI]

    Gordon Chalmers

    2006-10-13T23:59:59.000Z

    A configuration of light pulses is generated, together with emitters and receptors, that allows computing. The computing is extraordinarily high in number of flops per second, exceeding the capability of a quantum computer for a given size and coherence region. The emitters and receptors are based on the quantum diode, which can emit and detect individual photons with high accuracy.

  19. Residential Lighting

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiation Protection Technical squestionnairesquestionnaires AgreementLighting

  20. Optical phonons and the soft mode in 2H-NbSe2

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

    Weber, F.; Hott, R.; Heid, R.; Bohnen, K.-P.; Rosenkranz, S.; Castellan, J.-P.; Osborn, R.; Said, A. H.; Leu, B. M.; Reznik, D.

    2013-06-01T23:59:59.000Z

    We present an investigation of the lattice dynamics of the charge density wave (CDW) compound 2H-NbSe2. We analyze the precise nature of the wave vector-dependent electron-phonon coupling (EPC) and derive the bare dispersion of the CDW soft phonon mode using inelastic x-ray scattering combined with ab initio calculations. Experimentally, phonon modes along the ??M line, i.e., q = (h,0,0), with 0 ? h ? 0.5 and the same longitudinal symmetry (?1) as the CDW soft mode, were investigated up to 32 meV. In agreement with our calculations, we observe significant EPC in the optic modes at h ? 0.2. We analyze the EPC in the optic, as well as acoustic, mode and show that the q dependences stem from scattering processes between two bands at the Fermi surface that both have a Nb 4d character. Finally, we demonstrate that the soft mode dispersion at T = 33 K (=TCDW) can be well described on the basis of a strongly q-dependent EPC matrix element and an acousticlike bare phonon dispersion in agreement with observations near room temperature.

  1. Ab Initio Study of Phonon-Induced Dephasing of Electronic Excitations in

    E-Print Network [OSTI]

    Ab Initio Study of Phonon-Induced Dephasing of Electronic Excitations in Narrow Graphene Vibrational dephasing of the lowest energy electronic excitations in the perfect (16,16) graphene nanoribbon discovery came in 2004 with the isolation of single sheets of graphite, or graphene, by mechanical

  2. ccsd-00000617(version3):27Nov2003 Phonon dispersion in the 1-layer cuprate

    E-Print Network [OSTI]

    by Raman spectroscopy and with density-of-state data measured by inelastic neutron scattering. PACS numbers for inelastic neutron scattering (INS), that is the standard technique used to measure the dispersion of phonons investigate the low energy acoustical and optical modes in HgBa2CuO4+ using inelastic x-ray scattering (IXS

  3. PHYSICAL REVIEW B 84, 155417 (2011) Phonon-assisted transport through suspended carbon nanotube quantum dots

    E-Print Network [OSTI]

    2011-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 84, 155417 (2011) Phonon-assisted transport through suspended carbon nanotube, Lanzhou 730000, China 2 Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China 3 Beijing Computation Science Research Center, Beijing 100080, China (Received 14 August 2011; revised manuscript

  4. Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics

    E-Print Network [OSTI]

    Paxton, Benjamin John

    2006-01-01T23:59:59.000Z

    This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). ...

  5. Cage Breathing Lattice Dynamics of Skutterudites for Low Conductivity Predicted Phonon Conductivity

    E-Print Network [OSTI]

    Daly, Samantha

    and lattice dynamics simulations establish the range of atomic displacement parameters and values of Double-Substituted Pnicogen Rings We studied heat transport mechanisms on CoSb3(1-x)Ge1.5xTe1.5x using.5 where it becomes comparable to that of a Ba filler atom. Ge exhibits similar projected phonon dispersion

  6. INTERACTION DU CHAMP DE RAYONNEMENT AVEC DES PHONONS SIMPLES ET MULTIPLES

    E-Print Network [OSTI]

    Boyer, Edmond

    DU TYPE WURTZITE ET BLENDE Par M. BALKANSKI, M. NUSIMOVICI et R. LE TOULLEC, Laboratoire de Physique'interaction du champ électromagnétique avec un ou plusieurs phonons dans les réseaux du type Wurtzite : CdS, Zn, pour la Wurtzite, 12 branches de vibrations de réseau au centre de la zone de Brillouin. En raison des

  7. Confined electron-confined phonon scattering rates in wurtzite AlNGaNAlN heterostructures

    E-Print Network [OSTI]

    Confined electron-confined phonon scattering rates in wurtzite AlNÕGaNÕAlN heterostructures Evgenii in three-layered planar wurtzite AlN/GaN/AlN heterostructures with free-surface boundary conditions is discussed. Specific features of the deformation and piezoelectric scattering of electrons in wurtzite three

  8. Electronpolar optical phonon scattering suppression and mobility enhancement in wurtzite heterostructures

    E-Print Network [OSTI]

    Electron­polar optical phonon scattering suppression and mobility enhancement in wurtzite@ee.ucr.edu Abstract. We have shown theoretically that the electron mobility in wurtzite AlN/GaN/AlN heterostructures that the electron mobility can be enhanced in heterostructures made of wurtzite AlGaN/GaN/AlGaN semiconductors via

  9. Exciton-Phonon coupling in the finite temperature optical absorption of semiconductor

    E-Print Network [OSTI]

    Marini, Andrea

    #12;Polarons the Cardona-Allen approach PRB 23, 1495 (1981) I Is Using standard 1st and 2nd order, 1 (1969); RvL, PRB 69, 115110 (2004) Polarons, Hedin's equations, and Density Functional. Bobbert, PRB 72, 113202 (2005) Widely used Phonon overscreening [RvL, PRB 69, 115110 (2004)] Impossible

  10. Phonons and magnetic excitation correlations in weak ferromagnetic YCrO{sub 3}

    SciTech Connect (OSTI)

    Sharma, Yogesh; Sahoo, Satyaprakash, E-mail: satya504@gmail.com, E-mail: guptaraj@iitk.ac.in, E-mail: rkatiyar@hpcf.upr.edu; Perez, William; Katiyar, Ram S., E-mail: satya504@gmail.com, E-mail: guptaraj@iitk.ac.in, E-mail: rkatiyar@hpcf.upr.edu [Department of Physics, University of Puerto Rico, Puerto Rico 00936-8377 (United States); Mukherjee, Somdutta [Department of Physics, Indian Institute of Technology, Kanpur (India); Gupta, Rajeev, E-mail: satya504@gmail.com, E-mail: guptaraj@iitk.ac.in, E-mail: rkatiyar@hpcf.upr.edu [Department of Physics, Indian Institute of Technology, Kanpur (India); Department of Materials Science Programme, Indian Institute of Technology, Kanpur (India); Garg, Ashish [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur (India); Chatterjee, Ratnamala [Department of Physics, Indian Institute of Technology, Delhi (India)

    2014-05-14T23:59:59.000Z

    Here, we report the temperature dependent Raman spectroscopic studies on orthorhombically distorted perovskite YCrO{sub 3} over a temperature range of 20–300?K. Temperature dependence of DC-magnetization measurements under field cooled and zero field cooled protocols confirmed a Néel transition at T{sub N}???142?K. Magnetization isotherms recorded at 125?K show a clear loop opening without any magnetization saturation up to 20?kOe, indicating a coexistence of antiferromagnetic (AFM) and weak ferromagnetic (WFM) phases. Estimation of exchange constants using mean-field approximation further confirm the presence of a complex magnetic phase below T{sub N}. Temperature evolution of Raman line-shape parameters of the selected modes (associated with the octahedral rotation and A(Y)-shift in the unit-cell) reveal an anomalous phonon shift near T{sub N}. An additional phonon anomaly was identified at T{sup *}???60?K, which could possibly be attributed to the change in the spin dynamics. Moreover, the positive and negative shifts in Raman frequencies between T{sub N} and T{sup *} suggest competing WFM and AFM interactions. A close match between the phonon frequency of B{sub 3g} (3)-octahedral rotation mode with the square of sublattice magnetization between T{sub N} and T{sup *} is indicative of the presence of spin-phonon coupling in multiferroic YCrO{sub 3}.

  11. ENHANCEMENT OF SUPERCONDUCTING Tc IN Pd-H LIKE COMPOUNDS BY OPTICAL PHONONS

    E-Print Network [OSTI]

    Boyer, Edmond

    1227 ENHANCEMENT OF SUPERCONDUCTING Tc IN Pd-H LIKE COMPOUNDS BY OPTICAL PHONONS J. P. BURGER and D.450 1. Introduction. - The high superconducting tran- sition temperatures recently observed in Pd [1 interaction inhibiting superconductivity in pure Pd. As the density of states in Pd-H is rather similar [5

  12. Carrier recombination and generation rates for intravalley and intervalley phonon scattering in graphene

    E-Print Network [OSTI]

    Afshari, Ehsan

    in graphene Farhan Rana,* Paul A. George, Jared H. Strait, Jahan Dawlaty, Shriram Shivaraman, Mvs and recombination rates for intravalley and intervalley phonon scattering in graphene are presented. The transverse carriers in graphene. DOI: 10.1103/PhysRevB.79.115447 PACS number s : 73.63.Bd, 73.50.Gr, 72.10.Di, 73

  13. Phonon-like excitation in secondary and tertiary structure of hydrated protein Mingda Li,a

    E-Print Network [OSTI]

    Chen, Sow-Hsin

    Phonon-like excitation in secondary and tertiary structure of hydrated protein powders Mingda Li dispersion relations and their damping in two hydrated proteins, a-chymotrypsinogen A and casein, differing transition temperature TD: hydrated proteins are conformationally flexible and enzymatically active above TD

  14. Optical phonon decay in bulk aluminum nitride D. Y. Song and M. Holtza

    E-Print Network [OSTI]

    Holtz, Mark

    phonon properties of high-quality crystalline materials are thus of relevance to self-heating and any Tech University, Lubbock, Texas 79409 A. Chandolu and S. A. Nikishin Department of Electrical are generally abundant in dislocations, which strongly affect the optical and electrical properties. Recent

  15. Magneto-optical conductivity in graphene including electron-phonon coupling Adam Pound1

    E-Print Network [OSTI]

    Ahlers, Guenter

    8S 4M1 3 The Canadian Institute for Advanced Research, Toronto, Ontario, Canada, M5G 1Z8 and 4 of spectral weight in each Landau level (LL) into phonon-assisted peaks in the spectral function. Other new, upright cone forming the conduction band and the lower, inverted cone forming the valence band

  16. JOURNAL DE PHYSIQUE Colloque CS,suppltfmentau n" 6, Tome 41, juin 1980,page ~ 5 -2 4 1 SPIN-DEPENDENT RAMAN SCATTERING FROM PHONONS I N MAGNETIC SEMICONDUCTORS AND INSULATORS

    E-Print Network [OSTI]

    Boyer, Edmond

    -DEPENDENT RAMAN SCATTERING FROM PHONONS I N MAGNETIC SEMICONDUCTORS AND INSULATORS + ++G. Giintherodt, R. Merlin

  17. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

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

  18. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"ings of Aquifer Thermal Energy Storage Workshop, Lawrence

  19. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"Proceed- ings of Aquifer Thermal Energy Storage Workshop,

  20. Lighting Inventory Lighting Theatre and Drama

    E-Print Network [OSTI]

    Indiana University

    Lighting Inventory Lighting Theatre and Drama Description Totals R.Halls Wells- Metz Light ERS ETC SourceFour 25 25 50 degree ERS Strand Lighting 64 14 24 12 14 36 degree ERS ETC Source Four 15 15 36 degree ERS Strand Lighting 124 60 58 2 4 26 degree ERS ETC SourceFour 2 2 26 degree ERS Strand

  1. THERMAL HYDRAULICS KEYWORDS: thermal hydraulics,

    E-Print Network [OSTI]

    Smith, Barton L.

    -fluid modeling of nuclear reactor systems. Thermal-hydraulic analysis codes such as RELAP5-3D ~Ref. 1! and FLICA regions of the system. In fact, the CFD code FLUENT has previously been coupled to RELAP5-3D ~Refs. 3

  2. Thermal and Electric Conductivities of Coulomb Crystals in the Inner Crust of a Neutron Star

    E-Print Network [OSTI]

    D. A. Baiko; D. G. Yakovlev

    1996-04-28T23:59:59.000Z

    Thermal and electric conductivities of relativistic degenerate electrons are calculated for the case when electrons scatter by phonons in Coulomb crystals made of spherical finite--size nuclei at densities $10^{11}$~g/cm$^3 neutron star. In combination with the results of the previous article (for lower $\\rho$), simple unified fits are obtained which describe the kinetic coefficients in the range $10^3$~g/cm$^3 neutron stars and evolution of their magnetic fields. The difference between the kinetic coefficients in the neutron star crust composed of ground state and accreted matters is analyzed. Thermal drift of the magnetic field in the neutron star crust is discussed.

  3. LED Lighting Basics

    Broader source: Energy.gov [DOE]

    Light-Emitting diodes (LEDs) efficiently produce light in a fundamentally different way than any legacy or traditional source of light.

  4. Light Source

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9 5Let us count theLienertLift Forces in a Light

  5. Metallic halide lights and lighting systems. (Latest citations from the US Patent Bibliographic file with exemplary claims). Published Search

    SciTech Connect (OSTI)

    Not Available

    1994-11-01T23:59:59.000Z

    The bibliography contains citations of selected patents concerning the design and operation of metallic halide lights and lighting systems. High pressure, high intensity, and low wattage discharge lamps are described. Citations discuss power sources, lamp life, lamp control circuits, thermal switches, and heat reflective coatings. Applications in sport stadium lighting, vehicle headlights, and crop-lighting are included. (Contains a minimum of 170 citations and includes a subject term index and title list.)

  6. Threading plasmonic nanoparticle strings with light

    E-Print Network [OSTI]

    Herrmann, Lars O.; Valev, Ventsislav K.; Tserkezis, Christos; Barnard, Jonathan S.; Kasera, Setu; Scherman, Oren A.; Aizpurua, Javier; Baumberg, Jeremy J.

    2014-07-28T23:59:59.000Z

    by light induces large-scale threading, probed here across ml volumes (as depicted in Fig. 1b). Threads formed using unfocussed 805 nm, 200 fs, ultrafast laser pulses of 90MWcm#2; 2 intensity are directly seen in transmission electron microscopy (TEM... for this laser-induced assembly. Important factors for assembling nanomaterials with light. In our experiments, threading is achieved with high peak power (Ppeak) ultrafast laser pulses, which indicates that the process is non-thermal. In a non-thermal process...

  7. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has · STOP (Structural, Thermal, and Optical Performance) analyses of optical systems Thermal engineers lead evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

  8. Uv-Light Stabilization Additive Package For Solar Cell Module And Laminated Glass Applications

    DOE Patents [OSTI]

    Hanoka, Jack I. (Brookline, MA); Klemchuk, Peter P. (Watertown, CT)

    2002-03-05T23:59:59.000Z

    An ultraviolet light stabilization additive package is used in an encapsulant material that may be used in solar cell modules, laminated glass and a variety of other applications. The ultraviolet light stabilization additive package comprises a first hindered amine light stabilizer and a second hindered amine light stabilizer. The first hindered amine light stabilizer provides thermal oxidative stabilization, and the second hindered amine light stabilizer providing photo-oxidative stabilization.

  9. Thermal sensor with an improved coating

    DOE Patents [OSTI]

    LaDelfe, Peter C. (Los Alamos, NM); Stotlar, Suzanne C. (Los Alamos, NM)

    1986-01-01T23:59:59.000Z

    The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 .mu.m to about 5.6 .mu.m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

  10. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

    SciTech Connect (OSTI)

    Li, Chen [ORNL] [ORNL; Ma, Jie [ORNL] [ORNL; May, Andrew F [ORNL] [ORNL; Cao, Huibo [ORNL] [ORNL; Christianson, Andrew D [ORNL] [ORNL; Ehlers, Georg [ORNL] [ORNL; Singh, David J [ORNL] [ORNL; Sales, Brian C [ORNL] [ORNL; Delaire, Olivier A [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

  11. Major transitions in evolution linked to thermal gradients above hydrothermal vents

    E-Print Network [OSTI]

    Anthonie W. J. Muller

    2012-12-03T23:59:59.000Z

    The emergence of the main divisions of today's life: (1) unicellular prokaryotes, (2) unicellular eukaryotes, (3) multicellular eukaryotes, and (4) metazoans, are examples of the--still unexplained--major transitions in evolution. Regarding the origin of life, I have proposed that primordial life functioned as heat engine (thermosynthesis) while thermally cycled in convecting volcanic hot springs. Here I argue for a role of thermal gradients above submarine hydrothermal vents (SHV) in several major transitions. The last decade has witnessed the emergence of phononics, a novel discipline in physics based on controlled heat transport in thermal gradients. It builds thermal analogs to electronic devices: the thermal diode, the thermal transistor, the thermal switch, the thermal amplifier, the thermal memory--the thermal computer has been proposed. Encouraged by (1) the many similarities between microtubules (MT) and carbon nanotubes, which have a very high thermal conductivity, and (2) the recent discovery of a silk protein which also has a very high thermal conductivity, I combine and extend the mentioned ideas, and propose the general conjecture that several major transitions of evolution were effected by thermal processes, with four additional partial conjectures: (1) The first organisms used heat engines during thermosynthesis in convection cells; (2) The first eukaryotic cells used MT during thermosynthesis in the thermal gradient above SHV; (3) The first metazoans used transport of water or in water during thermosynthesis above SHV under an ice-covered ocean during the Gaskiers Snowball Earth; and (4) The first mammalian brain used a thermal machinery based on thermal gradients in or across the cortex. When experimentally proven these conjectures, which are testable by the methods of synthetic biology, would significantly enhance our understanding of life.

  12. Sustainable Office Lighting Options

    E-Print Network [OSTI]

    Massachusetts at Amherst, University of

    Sustainable Office Lighting Options Task Lighting: Task lighting is a localized method of lighting a workspace so that additional, unnecessary lighting is eliminated, decreasing energy usage and costs. Illumination levels in the targeted work areas are higher with task lighting than with the ambient levels

  13. Lattice Anharmonicity and Thermal Conductivity from Compressive Sensing of First-Principles Calculations

    SciTech Connect (OSTI)

    Zhou, Fei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nielson, Weston [Univ. of California, Los Angeles, CA (United States); Xia, Yi [Univ. of California, Los Angeles, CA (United States); Ozoli?š, Vidvuds [Univ. of California, Los Angeles, CA (United States)

    2014-10-01T23:59:59.000Z

    First-principles prediction of lattice thermal conductivity ?L of strongly anharmonic crystals is a long-standing challenge in solid-state physics. Making use of recent advances in information science, we propose a systematic and rigorous approach to this problem, compressive sensing lattice dynamics. Compressive sensing is used to select the physically important terms in the lattice dynamics model and determine their values in one shot. Nonintuitively, high accuracy is achieved when the model is trained on first-principles forces in quasirandom atomic configurations. The method is demonstrated for Si, NaCl, and Cu12Sb4S13, an earth-abundant thermoelectric with strong phonon-phonon interactions that limit the room-temperature ?L to values near the amorphous limit.

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

    SciTech Connect (OSTI)

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

    2015-01-01T23:59:59.000Z

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

  15. Thermal conductivity changes upon neutron transmutation of {sup 10}B doped diamond

    SciTech Connect (OSTI)

    Jagannadham, K., E-mail: jag-kasichainula@ncsu.edu [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Verghese, K. [Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Butler, J. E. [Code 6174, Naval research Laboratory, Washington, District of Columbia 20375 (United States)

    2014-08-28T23:59:59.000Z

    {sup 10}B doped p-type diamond samples were subjected to neutron transmutation reaction using thermal neutron flux of 0.9 × 10{sup 13} cm{sup ?2} s{sup ?1} and fast neutron flux of 0.09 × 10{sup 13} cm{sup ?2} s{sup ?1}. Another sample of epilayer grown on type IIa (110) single crystal diamond substrate was subjected to equal thermal and fast neutron flux of 10{sup 14}?cm{sup ?2} s{sup ?1}. The defects in the diamond samples were previously characterized by different methods. In the present work, thermal conductivity of these diamond samples was determined at room temperature by transient thermoreflectance method. The thermal conductivity change in the samples as a function of neutron fluence is explained by the phonon scattering from the point defects and disordered regions. The thermal conductivity of the diamond samples decreased more rapidly initially and less rapidly for larger neutron fluence. In addition, the thermal conductivity in type IIb diamond decreased less rapidly with thermal neutron fluence compared to the decrease in type IIa diamond subjected to fast neutron fluence. It is concluded that the rate of production of defects during transmutation reaction is slower when thermal neutrons are used. The thermal conductivity of epilayer of diamond subjected to high thermal and fast neutron fluence is associated with the covalent carbon network in the composite structure consisting of disordered carbon and sp{sup 2} bonded nanocrystalline regions.

  16. Low-Temperature Light Detectors with Neganov-Luke Amplification

    E-Print Network [OSTI]

    Isaila, C; Feilitzsch, F v; Gütlein, A; Kemmer, J; Lachenmaier, T; Lanfranchi, J -C; Pfister, S; Potzel, W; Roth, S; Sivers, M v; Strauss, R; Westphal, W; Wiest, F

    2011-01-01T23:59:59.000Z

    The simultaneous measurement of phonons and scintillation light induced by incident particles in a scintillating crystal such as CaWO4 is a powerful technique for the active rejection of background induced by gamma's and beta's as well as neutrons in direct Dark Matter searches. However, less than ~1% of the energy deposited in a CaWO4 crystal is detected as light. Thus, very sensitive light detectors are needed for an efficient event-by-event background discrimination. Due to the Neganov-Luke effect, the threshold of low-temperature light detectors based on semiconducting substrates can be improved significantly by drifting the photon-induced electron-hole pairs in an applied electric field. We present measurements with low-temperature light detectors based on this amplification mechanism. The Neganov-Luke effect makes it possible to improve the signal-to-noise ratio of our light detectors by a factor of ~9 corresponding to an energy threshold of ~21 eV. We also describe a method for an absolute energy calib...

  17. Exciton-phonon information flow in the energy transfer process of photosynthetic complexes

    E-Print Network [OSTI]

    Rebentrost, Patrick

    2010-01-01T23:59:59.000Z

    Non-Markovian and non-equilibrium phonon effects are believed to be key ingredients in the energy transfer in photosynthetic complexes, especially in complexes which exhibit a regime of intermediate exciton-phonon coupling. In this work, we harness a recently developed measure for non-Markovianity to elucidate the information flow between electronic and vibrational degrees of freedom. We study the measure in the hierarchical equation of motion approach which captures strong system-bath coupling effects and non-equilibrium molecular reorganization. We find that, for a model dimer system and the Fenna-Matthews-Olson complex, non-Markovianity is significant under realistic physiological conditions. A first step towards experimental quantification is provided by the study of four-wave mixing initial states.

  18. Neutrino-Pair Emission due to Electron-Phonon Scattering in a Neutron Star Crust

    E-Print Network [OSTI]

    D. G. Yakovlev; A. D. Kaminker

    1996-04-19T23:59:59.000Z

    Neutrino-pair bremsstrahlung radiation is considered due to electron--phonon scattering of degenerate, relativistic electrons in a lattice of spherical atomic nuclei in a neutron star crust. The neutrino energy generation rate is calculated taking into account exact spectrum of phonons, the Debye--Waller factor, and the nuclear form--factor in the density range from $10^7$~g~cm$^{-3}$ to $10^{14}$~g~cm$^{-3}$ at arbitrary nuclear composition for body-centered-cubic and face-centered-cubic Coulomb crystals. The results are fitted by a unified analytic expression. A comparison is given of the neutrino bremsstrahlung energy losses in a neutron star crust composed of ground state and accreted matter, in the solid and liquid phases.

  19. Observation of phononic helical edge states in a mechanical 'topological insulator'

    E-Print Network [OSTI]

    Süsstrunk, Roman

    2015-01-01T23:59:59.000Z

    A topological insulator is characterized by a dichotomy between the interior and the edge of a finite system: While the bulk has a non-zero energy gap, the edges are forced to sustain excitations traversing these gaps. Originally proposed for electrons governed by quantum mechanics, it has remained an important open question if the same physics can be observed for systems obeying Newton's equations of motion. Here, we report on measurements that characterize the collective behavior of mechanical oscillators exhibiting the phenomenology of the quantum spin hall effect. The phononic edge modes are shown to be helical and we demonstrate their topological protection via the stability against imperfections. Our results open the door to the design of topological acoustic meta-materials that can capitalize on the stability of the surfaces phonons as reliable wave guides.

  20. Parametric amplification of orbital angular momentum beams based on light-acoustic interaction

    E-Print Network [OSTI]

    Gao, Wei; Li, Hongwei; Shi, Guangyao; Zhu, Zhihan

    2015-01-01T23:59:59.000Z

    A high fidelity amplification of beams carrying orbital angular momentum (OAM) is very crucial for OAM multiplexing and other OAM-based applications. Here, we report the first study of stimulated Brillouin amplification (SBA) for OAM beams, the energy conversion efficiency of photon-phonon coupling and the phase structure of amplified signals are investigated in collinear and noncollinear frame systems, respectively. Our results demonstrate that the OAM signals can be efficiently amplified without obvious noise introduced, and the modes of output signal is independent of the pump modes or the geometrical frames. Meanwhile, an OAM state depending on the optical modes and the geometrical frames is loaded into phonons by coherent light-acoustic interaction, which reveals more fundamental significance and a great application potential in OAM-multiplexing.

  1. Thermal conductivity of self-assembled nano-structured ZnO bulk ceramics

    SciTech Connect (OSTI)

    Zhao, Yu [Bio-Inspired Materials and Devices Laboraory (BMDL); Yan, Yongke [Bio-Inspired Materials and Devices Laboraory (BMDL); Kumar, Ashok [Bio-Inspired Materials and Devices Laboraory (BMDL); Wang, Hsin [ORNL; Porter, Wallace D [ORNL

    2012-01-01T23:59:59.000Z

    In this study, we describe the changes in thermal conductivity behavior of ZnO-Al micro- and nano-two-phase self-assembled composites with varying grain sizes. The reduction in thermal conductivity values of micro-composites was limited to {approx}15% for ZnO-4% Al. However, nano-composites exhibited large reduction, by a factor of about three, due to uniform distribution of nano-precipitates (ZnAl2O4) and large grain boundary area. Interestingly, the micro-composites revealed continuous decrease in thermal conductivity with increase in Al substitution while the nano-composites exhibited the lowest magnitudes for 2% Al concentration. Raman spectra indicated that phonon confinement in ZnO-Al nano-composites causes drastic decrease in the value of thermal conductivity.

  2. Controls for Solid-State Lighting

    SciTech Connect (OSTI)

    Rubinstein, Francis

    2007-06-22T23:59:59.000Z

    This study predicts new hybrid lighting applications for LEDs. In hybrid lighting, LEDs provide a low-energy 'standby' light level while another, more powerful, efficient light source provides light for occupied periods. Lighting controls will allow the two light sources to work together through an appropriate control strategy, typically motion-sensing. There are no technical barriers preventing the use of low through high CRI LEDs for standby lighting in many interior and exterior applications today. The total luminous efficacy of LED systems could be raised by increasing the electrical efficiency of LED drivers to the maximum practically achievable level (94%). This would increase system luminous efficacy by 20-25%. The expected market volumes for many types of LEDs should justify the evolution of new LED drivers that use highly efficient ICs and reduce parts count by means of ASICs. Reducing their electronics parts count by offloading discrete components onto integrated circuits (IC) will allow manufacturers to reduce the cost of LED driver electronics. LED luminaire manufacturers will increasingly integrate the LED driver and thermal management directly in the LED fixture. LED luminaires of the future will likely have no need for separable lamp and ballast because the equipment life of all the LED luminaire components will all be about the same (50,000 hours). The controls and communications techniques used for communicating with conventional light sources, such as dimmable fluorescent lighting, are appropriate for LED illumination for energy management purposes. DALI has been used to control LED systems in new applications and the emerging ZigBee protocol could be used for LEDs as well. Major lighting companies are already moving in this direction. The most significant finding is that there is a significant opportunity to use LEDs today for standby lighting purposes. Conventional lighting systems can be made more efficient still by using LEDs to provide a low-energy standby state when lower light levels are acceptable.

  3. Covariant density functional theory with two-phonon coupling in nuclei

    SciTech Connect (OSTI)

    Ring, P.; Litvinova, E.; Tselyaev, V. [Physik Department, Technische Universitat Muenchen, D-85747 Garching (Germany) and State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Nuclear Physics Department, St. Petersburg State University, 198504 St. Petersburg (Russian Federation)

    2012-10-20T23:59:59.000Z

    A full description of excited states within the framework of density functional theory requires energy dependent self energies. We present a new class of many-body models. It allows a parameter free description of the fragmentation of nuclear states induced by mode coupling of two-quasiparticle and two-phonon configurations. The method is applied for an investigation of low-lying dipole excitations in Sn isotopes with large neutron excess.

  4. Magnetic Oscillation of Optical Phonon in ABA- and ABC-Stacked Trilayer Graphene

    E-Print Network [OSTI]

    Cong, Chunxiao; Cao, Bingchen; Qiu, Caiyu; Shen, Xiaonan; Ferreira, Aires; Adam, Shaffique; Yu, Ting

    2015-01-01T23:59:59.000Z

    We present a comparative measurement of the G-peak oscillations of phonon frequency, Raman intensity and linewidth in the Magneto-Raman scattering of optical E2g phonons in mechanically exfoliated ABA- and ABC-stacked trilayer graphene (TLG). Whereas in ABA-stacked TLG, we observe magnetophonon oscillations consistent with single-bilayer chiral band doublets, the features are flat for ABC-stacked TLG up to magnetic fields of 9 T. This suppression can be attributed to the enhancement of band chirality that compactifies the spectrum of Landau levels and modifies the magnetophonon resonance properties. The drastically different coupling behaviour between the electronic excitations and the E2g phonons in ABA- and ABC-stacked TLG reflects their different electronic band structures and the electronic Landau level transitions and thus can be another way to determine the stacking orders and to probe the stacking-order-dependent electronic structures. In addition, the sensitivity of the magneto-Raman scattering to the...

  5. Lattice vibrations in the Frenkel-Kontorova model. I. phonon dispersion, number density, and energy

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

    Meng, Qingping; Wu, Lijun; Welch, David O.; Zhu, Yimei

    2015-06-01T23:59:59.000Z

    We studied the lattice vibrations of two inter-penetrating atomic sublattices via the Frenkel-Kontorova (FK) model of a linear chain of harmonically interacting atoms subjected to an on-site potential, using the technique of thermodynamic Green's functions based on quantum field-theoretical methods. General expressions were deduced for the phonon frequency-wave-vector dispersion relations, number density, and energy of the FK model system. As the application of the theory, we investigated in detail cases of linear chains with various periods of the on-site potential of the FK model. Some unusual but interesting features for different amplitudes of the on-site potential of the FK modelmore »are discussed. In the commensurate structure, the phonon spectrum always starts at a finite frequency, and the gaps of the spectrum are true ones with a zero density of modes. In the incommensurate structure, the phonon spectrum starts from zero frequency, but at a non-zero wave vector; there are some modes inside these gap regions, but their density is very low. In our approximation, the energy of a higher-order commensurate state of the one-dimensional system at a finite temperature may become indefinitely close to the energy of an incommensurate state. This finding implies that the higher-order incommensurate-commensurate transitions are continuous ones and that the phase transition may exhibit a “devil's staircase” behavior at a finite temperature.« less

  6. Thermal conductivity of thermal-battery insulations

    SciTech Connect (OSTI)

    Guidotti, R.A.; Moss, M.

    1995-08-01T23:59:59.000Z

    The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.

  7. Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

    DOE Patents [OSTI]

    Krupke, William F. (Pleasanton, CA); Payne, Stephen A. (Castro Valley, CA); Marshall, Christopher D. (Livermore, CA)

    2001-01-01T23:59:59.000Z

    The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

  8. 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...

  9. Lighting Options for Homes.

    SciTech Connect (OSTI)

    Baker, W.S.

    1991-04-01T23:59:59.000Z

    This report covers many aspects of various lighting options for homes. Types of light sources described include natural light, artificial light, incandescent lamps, fluorescent lamps, and high intensity discharge lamps. A light source selection guide gives the physical characteristics of these, design considerations, and common applications. Color, strategies for efficient lighting, and types of lighting are discussed. There is one section giving tips for various situations in specific rooms. Rooms and types of fixtures are shown on a matrix with watts saved by using the recommended type lighting for that room and room location. A major emphasis of this report is saving energy by utilizing the most suitable, recommended lighting option. (BN)

  10. Mobile lighting apparatus

    DOE Patents [OSTI]

    Roe, George Michael; Klebanoff, Leonard Elliott; Rea, Gerald W; Drake, Robert A; Johnson, Terry A; Wingert, Steven John; Damberger, Thomas A; Skradski, Thomas J; Radley, Christopher James; Oros, James M; Schuttinger, Paul G; Grupp, David J; Prey, Stephen Carl

    2013-05-14T23:59:59.000Z

    A mobile lighting apparatus includes a portable frame such as a moveable trailer or skid having a light tower thereon. The light tower is moveable from a stowed position to a deployed position. A hydrogen-powered fuel cell is located on the portable frame to provide electrical power to an array of the energy efficient lights located on the light tower.

  11. Light disappears rapidly (exponentially)

    E-Print Network [OSTI]

    Kudela, Raphael M.

    #12;#12;#12;#12;Light disappears rapidly (exponentially) with depth At the same time, the color of the light shifts #12;#12;#12;#12;· Euphotic zone ­ plentiful light ­ 0-100 m (about) · Dysphotic zone ­ very, very little light ­ 100-1000 m (about) · Aphotic zone ­ no light ­ below 1000 m #12;Sunlight in Water

  12. Pulse thermal processing of functional materials using directed plasma arc

    DOE Patents [OSTI]

    Ott, Ronald D. (Knoxville, TN); Blue, Craig A. (Knoxville, TN); Dudney, Nancy J. (Knoxville, TN); Harper, David C. (Kingston, TN)

    2007-05-22T23:59:59.000Z

    A method of thermally processing a material includes exposing the material to at least one pulse of infrared light emitted from a directed plasma arc to thermally process the material, the pulse having a duration of no more than 10 s.

  13. Seasonal thermal energy storage

    SciTech Connect (OSTI)

    Allen, R.D.; Kannberg, L.D.; Raymond, J.R.

    1984-05-01T23:59:59.000Z

    This report describes the following: (1) the US Department of Energy Seasonal Thermal Energy Storage Program, (2) aquifer thermal energy storage technology, (3) alternative STES technology, (4) foreign studies in seasonal thermal energy storage, and (5) economic assessment.

  14. New Light Sources for Tomorrow's Lighting Designs

    E-Print Network [OSTI]

    Krailo, D. A.

    can ever be saved on that monthly energy bill. During the past several years, many new light sources have been developed and introduced. These product introductions have not been limited to anyone lamp type, but instead may be found in fila ment..., fluorescent and high intensity discharge lamp families. Man , ufacturers of light sources have two basic goals for new product development. These goals are high efficiency lighting and improved colo'r rendering properties. High efficiency lighting may take...

  15. EK101 Engineering Light Smart Lighting

    E-Print Network [OSTI]

    Bifano, Thomas

    EK101 Engineering Light Smart Lighting Homework for 9/10 1. Make an estimate (using if the patent is granted.) 3. What is a lumen? A lux? How are the two related? How would you use a lux meter, (Lux, Lumens/m2) Luminous Flux: Perceivable light power from a source, (Lumens) Use the lux meter

  16. Polymer and small molecule based hybrid light source

    DOE Patents [OSTI]

    Choong, Vi-En (Carlsbad, CA); Choulis, Stelios (Nuremberg, DE); Krummacher, Benjamin Claus (Regensburg, DE); Mathai, Mathew (Monroeville, PA); So, Franky (Gainesville, FL)

    2010-03-16T23:59:59.000Z

    An organic electroluminescent device, includes: a substrate; a hole-injecting electrode (anode) coated over the substrate; a hole injection layer coated over the anode; a hole transporting layer coated over the hole injection layer; a polymer based light emitting layer, coated over the hole transporting layer; a small molecule based light emitting layer, thermally evaporated over the polymer based light emitting layer; and an electron-injecting electrode (cathode) deposited over the electroluminescent polymer layer.

  17. 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....

  18. Solar Thermal Powered Evaporators

    E-Print Network [OSTI]

    Moe, Christian Robert

    2015-01-01T23:59:59.000Z

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

  19. Specific light in sculpture

    E-Print Network [OSTI]

    Powell, John William

    1989-01-01T23:59:59.000Z

    Specific light is defined as light from artificial or altered natural sources. The use and manipulation of light in three dimensional sculptural work is discussed in an historic and contemporary context. The author's work ...

  20. Light front Casimir effect at finite temperature

    E-Print Network [OSTI]

    P. L. M. Rodrigues; Silvana Perez; Danilo T. Alves; Van Sérgio Alves; Charles R. Silva

    2015-01-06T23:59:59.000Z

    The correct description of the standard Casimir effect for periodic boundary conditions via light front formalism implies in these conditions imposed at fixed Minkowski times [Almeida {\\it et al.} Phys. Rev. {\\bf D 87}, 065028 (2013); Chabysheva and Hiller, Phys. Rev. {\\bf D 88}, 085006 (2013)] instead of fixed light front times. The unphysical nature of this latter condition is manifested in the vacuum part by no regularization yielding a finite Casimir energy density [Lenz and Steinbacher, Phys. Rev. {\\bf D 67}, 045010 (2003)]. In the present paper, we extend this discussion and analyze the problem of the light front quantization with simultaneous presence of a thermal bath and boundary conditions. Considering both the oblique light front as well as Dirac light front coordinates, we show that the imposition of periodic boundary conditions at fixed Minkowski times recovers the expected behaviors for the energy density and Casimir entropy. We also investigate how the unphysical nature of the periodic boundary conditions imposed at fixed light front times manifests in the thermal part of the energy and entropy, showing that in the classical limit the Casimir entropy decreases linearly with the temperature (not becoming independent of the temperature as expected), and also that the Kirchhoff theorem is not respected.

  1. Radiative cooling of bulk silicon by incoherent light pump

    SciTech Connect (OSTI)

    Malyutenko, V. K., E-mail: malyut@isp.kiev.ua; Bogatyrenko, V. V.; Malyutenko, O. Yu. [V. E. Lashkaryov Institute of Semiconductor Physics, 03028 Kiev (Ukraine)] [V. E. Lashkaryov Institute of Semiconductor Physics, 03028 Kiev (Ukraine)

    2013-12-23T23:59:59.000Z

    In contrast to radiative cooling by light up conversion caused exclusively by a low-entropy laser pump and employing thermally assisted fluorescence/luminescence as a power out, we demonstrate light down conversion cooling by incoherent pumps, 0.47–0.94??m light emitting diodes, and employing thermal emission (TE) as a power out. We demonstrate ?3.5?K bulk cooling of Si at 450?K because overall energy of multiple below bandgap TE photons exceeds the energy of a single above bandgap pump photon. We show that using large entropy TE as power out helps avoid careful tuning of an incoherent pump wavelength and cool indirect-bandgap semiconductors.

  2. Light Duty Combustion Research: Advanced Light-Duty Combustion...

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

    Light Duty Combustion Research: Advanced Light-Duty Combustion Experiments Light Duty Combustion Research: Advanced Light-Duty Combustion Experiments 2009 DOE Hydrogen Program and...

  3. Exciting White Lighting

    Broader source: Energy.gov [DOE]

    Windows that emit light and are more energy efficient? Universal Display’s PHOLED technology enables windows that have transparent light-emitting diodes in them.

  4. Phonon-mediated squeezing of the cavity field off-resonantly coupled with a coherently driven quantum dot

    SciTech Connect (OSTI)

    Zhu, Jia-pei [Department of Physics, Huazhong Normal University, Wuhan 430079 (China); College of Science, Honghe University, Mengzi 661100 (China); Huang, Hui; Li, Gao-xiang, E-mail: gaox@phy.ccnu.edu.cn [Department of Physics, Huazhong Normal University, Wuhan 430079 (China)

    2014-01-21T23:59:59.000Z

    We theoretically propose a scheme for the quadrature squeezing of the cavity field via dissipative processes. The effects of the electron-phonon interaction (EPI) on the squeezing are investigated, where the cavity is off-resonantly coupled with a coherently driven quantum dot (QD) which is allowed to interact with an acoustic-phonon reservoir. Under certain conditions, the participation of the phonon induced by both the EPI and the off-resonant coupling of the cavity with the QD enables some dissipative processes to occur resonantly in the dressed-state basis of the QD. The cavity-mode photons emitted or absorbed during the phonon-mediated dissipative processes are correlated, thus leading to the squeezing of the cavity field. A squeezed vacuum reservoir for the cavity field is built up due to the EPI plus the off-resonant coupling between the cavity and the QD. The numerical results obtained with an effective polaron master equation derived using second-order perturbation theory indicate that, in low temperature limit, the degree of squeezing is maximal but the increasing temperature of the phonon reservoir could hinder the squeezing and degrade the degree of the squeezing of the cavity field. In addition, the presence of the photonic crystal could enhance the quadrature squeezing of the cavity field.

  5. Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

    SciTech Connect (OSTI)

    Zhou, X.J.

    2010-04-30T23:59:59.000Z

    In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not thought possible only a decade ago. This revolution of the ARPES technique and its scientific impact result from dramatic advances in four essential components: instrumental resolution and efficiency, sample manipulation, high quality samples and well-matched scientific issues. The purpose of this treatise is to go through the prominent results obtained from ARPES on cuprate superconductors. Because there have been a number of recent reviews on the electronic structures of high-T{sub c} materials, we will mainly present the latest results not covered previously, with a special attention given on the electron-phonon interaction in cuprate superconductors. What has emerged is rich information about the anomalous electron-phonon interaction well beyond the traditional views of the subject. It exhibits strong doping, momentum and phonon symmetry dependence, and shows complex interplay with the strong electron-electron interaction in these materials. ARPES experiments have been instrumental in identifying the electronic structure, observing and detailing the electron-phonon mode coupling behavior, and mapping the doping evolution of the high-T{sub c} cuprates. The spectra evolve from the strongly coupled, polaronic spectra seen in underdoped cuprates to the Migdal-Eliashberg like spectra seen in the optimally and overdoped cuprates. In addition to the marked doping dependence, the cuprates exhibit pronounced anisotropy with direction in the Brillouin zone: sharp quasiparticles along the nodal direction that broaden significantly in the anti-nodal region of the underdoped cuprates, an anisotropic electron-phonon coupling vertex for particular modes identified in the optimal and overdoped compounds, and preferential scattering across the two parallel pieces of Fermi surface in the antinodal region for all doping levels. This also contributes to the pseudogap effect. To the extent that the Migdal-Eliashberg picture applies, the spectra of the cuprates bear resemblance to that seen in established strongly coupled electron-phonon superconductors such as Pb. On the other

  6. Thermal hydraulics development for CASL

    SciTech Connect (OSTI)

    Lowrie, Robert B [Los Alamos National Laboratory

    2010-12-07T23:59:59.000Z

    This talk will describe the technical direction of the Thermal-Hydraulics (T-H) Project within the Consortium for Advanced Simulation of Light Water Reactors (CASL) Department of Energy Innovation Hub. CASL is focused on developing a 'virtual reactor', that will simulate the physical processes that occur within a light-water reactor. These simulations will address several challenge problems, defined by laboratory, university, and industrial partners that make up CASL. CASL's T-H efforts are encompassed in two sub-projects: (1) Computational Fluid Dynamics (CFD), (2) Interface Treatment Methods (ITM). The CFD subproject will develop non-proprietary, scalable, verified and validated macroscale CFD simulation tools. These tools typically require closures for their turbulence and boiling models, which will be provided by the ITM sub-project, via experiments and microscale (such as DNS) simulation results. The near-term milestones and longer term plans of these two sub-projects will be discussed.

  7. Thermal conductivity of silicene from first-principles

    SciTech Connect (OSTI)

    Xie, Han; Bao, Hua, E-mail: hum@ghi.rwth-aachen.de, E-mail: hua.bao@sjtu.edu.cn [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Hu, Ming, E-mail: hum@ghi.rwth-aachen.de, E-mail: hua.bao@sjtu.edu.cn [Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University, Aachen 52064 (Germany); Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, Aachen 52062 (Germany)

    2014-03-31T23:59:59.000Z

    Silicene, as a graphene-like two-dimensional material, now receives exceptional attention of a wide community of scientists and engineers beyond graphene. Despite extensive study on its electric property, little research has been done to accurately calculate the phonon transport of silicene so far. In this paper, thermal conductivity of monolayer silicene is predicted from first-principles method. At 300?K, the thermal conductivity of monolayer silicene is found to be 9.4?W/mK and much smaller than bulk silicon. The contributions from in-plane and out-of-plane vibrations to thermal conductivity are quantified, and the out-of-plane vibration contributes less than 10% of the overall thermal conductivity, which is different from the results of the similar studies on graphene. The difference is explained by the presence of small buckling, which breaks the reflectional symmetry of the structure. The flexural modes are thus not purely out-of-plane vibration and have strong scattering with other modes.

  8. JOURNAL DE PHYSIQUE Colloque C6, supplment au n 8, Tome 39, aot 1978, page C6-988 RESONANT SCATTERING OF MONOCHROMATIC PHONONS BY MAGNONS IN MnF AND IN YIG

    E-Print Network [OSTI]

    Boyer, Edmond

    ). Abstract.- By using phonon spectroscopy with superconducting tunneling junctions resonant scattering with superconductinr tunneling junctions /6/. For phonon spectroscopy at 1 K we used PbBi alloy junctions as generators

  9. PFP Emergency Lighting Study

    SciTech Connect (OSTI)

    BUSCH, M.S.

    2000-02-02T23:59:59.000Z

    NFPA 101, section 5-9 mandates that, where required by building classification, all designated emergency egress routes be provided with adequate emergency lighting in the event of a normal lighting outage. Emergency lighting is to be arranged so that egress routes are illuminated to an average of 1.0 footcandle with a minimum at any point of 0.1 footcandle, as measured at floor level. These levels are permitted to drop to 60% of their original value over the required 90 minute emergency lighting duration after a power outage. The Plutonium Finishing Plant (PFP) has two designations for battery powered egress lights ''Emergency Lights'' are those battery powered lights required by NFPA 101 to provide lighting along officially designated egress routes in those buildings meeting the correct occupancy requirements. Emergency Lights are maintained on a monthly basis by procedure ZSR-12N-001. ''Backup Lights'' are battery powered lights not required by NFPA, but installed in areas where additional light may be needed. The Backup Light locations were identified by PFP Safety and Engineering based on several factors. (1) General occupancy and type of work in the area. Areas occupied briefly during a shiftly surveillance do not require backup lighting while a room occupied fairly frequently or for significant lengths of time will need one or two Backup lights to provide general illumination of the egress points. (2) Complexity of the egress routes. Office spaces with a standard hallway/room configuration will not require Backup Lights while a large room with several subdivisions or irregularly placed rooms, doors, and equipment will require Backup Lights to make egress safer. (3) Reasonable balance between the safety benefits of additional lighting and the man-hours/exposure required for periodic light maintenance. In some plant areas such as building 236-Z, the additional maintenance time and risk of contamination do not warrant having Backup Lights installed in all rooms. Sufficient light for egress is provided by existing lights located in the hallways.

  10. Method and apparatus for thermal management of vehicle exhaust systems

    DOE Patents [OSTI]

    Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

    1995-01-01T23:59:59.000Z

    A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter.

  11. DDbar Correlations probing Thermalization in High-Energy Nuclear Collisions

    E-Print Network [OSTI]

    K. Schweda; X. Zhu; M. Bleicher; S. L. Huang; H. Stoecker; N. Xu; P. Zhuang

    2006-10-30T23:59:59.000Z

    We propose to measure azimuthal correlations of heavy-flavor hadrons to address the status of thermalization at the partonic stage of light quarks and gluons in high-energy nuclear collisions. In particular, we show that hadronic interactions at the late stage cannot significantly disturb the initial back-to-back azimuthal correlations of DDbar pairs. Thus, a decrease or the complete absence of these initial correlations does indicate frequent interactions of heavy-flavor quarks and also light partons in the partonic stage, which are essential for the early thermalization of light partons.

  12. First principles electronic band structure and phonon dispersion curves for zinc blend beryllium chalcogenide

    SciTech Connect (OSTI)

    Dabhi, Shweta, E-mail: venu.mankad@gmail.com; Mankad, Venu, E-mail: venu.mankad@gmail.com; Jha, Prafulla K., E-mail: venu.mankad@gmail.com [Department of Physics, Maharaja Krishnakumasinhji Bhavnagar University, Bhavnagar-364001 (India)

    2014-04-24T23:59:59.000Z

    A detailed theoretical study of structural, electronic and Vibrational properties of BeX compound is presented by performing ab-initio calculations based on density-functional theory using the Espresso package. The calculated value of lattice constant and bulk modulus are compared with the available experimental and other theoretical data and agree reasonably well. BeX (X = S,Se,Te) compounds in the ZB phase are indirect wide band gap semiconductors with an ionic contribution. The phonon dispersion curves are represented which shows that these compounds are dynamically stable in ZB phase.

  13. Cooling carbon nanotubes to the phononic ground state with constant electron current

    E-Print Network [OSTI]

    Stefano Zippilli; Giovanna Morigi; Adrian Bachtold

    2009-03-06T23:59:59.000Z

    We present a quantum theory of cooling of a mechanical resonator using back-action with constant electron current. The resonator device is based on a doubly clamped nanotube, which mechanically vibrates and acts as a double quantum dot for electron transport. Mechanical vibrations and electrons are coupled electrostatically using an external gate. The fundamental eigenmode is cooled by absorbing phonons when electrons tunnel through the double quantum dot. We identify the regimes in which ground state cooling can be achieved for realistic experimental parameters.

  14. Indication of Te segregation in laser-irradiated ZnTe observed by in situ coherent-phonon spectroscopy

    SciTech Connect (OSTI)

    Shimada, Toru [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany); Hirosaki University, 1 Bunkyo-cho, Hirosaki, Aomori 036-8152 (Japan); Kamaraju, N., E-mail: nkamaraju@lanl.gov [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany); Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Los Alamos, New Mexico 87545 (United States); Frischkorn, Christian [Department of Physics, Free University of Berlin, Arnimallee 14, 14195 Berlin (Germany); Wolf, Martin; Kampfrath, Tobias [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-09-15T23:59:59.000Z

    We irradiate a ZnTe single crystal with 10-fs laser pulses at a repetition rate of 80?MHz and investigate its resulting gradual modification by means of coherent-phonon spectroscopy. We observe the emergence of a phonon mode at about 3.6?THz whose amplitude and lifetime grow monotonously with irradiation time. The speed of this process depends sensitively on the pump-pulse duration. Our observations strongly indicate that the emerging phonon mode arises from a Te phase induced by multiphoton absorption of incident laser pulses. A potential application of our findings is laser-machining of microstructures in the bulk of a ZnTe crystal, a highly relevant electrooptic material.

  15. Shear-horizontal surface acoustic wave phononic device with high density filling material for ultra-low power sensing applications

    SciTech Connect (OSTI)

    Richardson, M.; Bhethanabotla, V. R., E-mail: bhethana@usf.edu [Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, Florida 33620 (United States); Sankaranarayanan, S. K. R. S. [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-06-23T23:59:59.000Z

    Finite element simulations of a phononic shear-horizontal surface acoustic wave (SAW) sensor based on ST 90°-X Quartz reveal a dramatic reduction in power consumption. The phononic sensor is realized by artificially structuring the delay path to form an acoustic meta-material comprised of a periodic microcavity array incorporating high-density materials such as tantalum or tungsten. Constructive interference of the scattered and secondary reflected waves at every microcavity interface leads to acoustic energy confinement in the high-density regions translating into reduced power loss. Tantalum filled cavities show the best performance while tungsten inclusions create a phononic bandgap. Based on our simulation results, SAW devices with tantalum filled microcavities were fabricated and shown to significantly decrease insertion loss. Our findings offer encouraging prospects for designing low power, highly sensitive portable biosensors.

  16. Ballistic thermal transport in a cylindrical semiconductor nanowire modulated with bridge contacts

    SciTech Connect (OSTI)

    Zhang, Yong, E-mail: apzhangyong@126.com; Xie, Zhong-Xiang, E-mail: xiezxhu@163.com; Yu, Xia; Wang, Hai-Bin [Department of Mathematics and Physics, Hunan Institute of Technology, Hengyang 421002 (China); Li, Ke-Min [Department of Physics and Electronics Information, Hunan Institute of Science and Technology, Yueyang 414004 (China)

    2014-10-14T23:59:59.000Z

    Using the scattering-matrix method, we studied ballistic phonon transmission and thermal conductance at low temperatures in a cylindrical quantum wire with bridge contacts. The transmission coefficient exhibited a stepped profile, which became more evident as the bridge radius increased. When the dimensions of the bridge are identical to those of main wires, we observed a quantum platform of the thermal conductance, even in the presence of interface scattering. When the dimensions of the bridge are smaller than those of main wires, however, we could not observe the quantum platform. We also revealed other interesting physical properties, such as universal quantum thermal conductance and resonant transmission. A brief analysis of these results is given.

  17. Anomalous pressure dependence of thermal conductivities of large mass ratio compounds

    SciTech Connect (OSTI)

    Lindsay, Lucas R [ORNL; Broido, David [Boston College, Chestnut Hill; Carrete, Jesus [French Alternative Energies and Atomic Energy Commission (CEA), Grenoble; Mingo, Natalio [French Alternative Energies and Atomic Energy Commission (CEA), Grenoble; Reinecke, Tom [Naval Research Laboratory, Washington, D.C.

    2015-01-01T23:59:59.000Z

    The lattice thermal conductivities ( ) of binary compound materials are examined as a function of hydrostatic pressure, P, using a first-principles approach. Compound materials with relatively small mass ratios, such as MgO, show an increase in with P, consistent with measurements. Conversely, compounds with large mass ratios (e.g., BSb, BAs, BeTe, BeSe) exhibit decreasing with increasing P, a behavior that cannot be understood using simple theories of . This anomalous P dependence of arises from the fundamentally different nature of the intrinsic scattering processes for heat-carrying acoustic phonons in large mass ratio compounds compared to those with small mass ratios. This work demonstrates the power of first principles methods for thermal properties and advances the understanding of thermal transport in non-metals.

  18. Stable isotope fractionation by thermal diffusion through partially molten wet and dry silicate rocks

    E-Print Network [OSTI]

    Bindeman, Ilya N.

    isotope redistribution by thermal diffusion leading to enrichment of light isotopes at the hot endStable isotope fractionation by thermal diffusion through partially molten wet and dry silicate 2012 Editor: T.M. Harrison Keywords: thermal diffusion hydrogen isotope separation oxygen isotopes

  19. Thermal element for maintaining minimum lamp wall temperature in fluorescent fixtures

    DOE Patents [OSTI]

    Siminovitch, M.J.

    1992-11-10T23:59:59.000Z

    In a lighting fixture including a lamp and a housing, an improvement is disclosed for maintaining a lamp envelope area at a cooler, reduced temperature relative to the enclosed housing ambient. The improvement comprises a thermal element in thermal communication with the housing extending to and springably urging thermal communication with a predetermined area of the lamp envelope surface. 12 figs.

  20. Thermal element for maintaining minimum lamp wall temperature in fluorescent fixtures

    DOE Patents [OSTI]

    Siminovitch, Michael J. (Richmond, CA)

    1992-01-01T23:59:59.000Z

    In a lighting fixture including a lamp and a housing, an improvement is disclosed for maintaining a lamp envelope area at a cooler, reduced temperature relative to the enclosed housing ambient. The improvement comprises a thermal element in thermal communication with the housing extending to and springably urging thermal communication with a predetermined area of the lamp envelope surface.

  1. Zone-boundary phonons in hexagonal and cubic GaN H. Siegle, G. Kaczmarczyk, L. Filippidis, A. P. Litvinchuk, A. Hoffmann, and C. Thomsen

    E-Print Network [OSTI]

    Nabben, Reinhard

    Zone-boundary phonons in hexagonal and cubic GaN H. Siegle, G. Kaczmarczyk, L. Filippidis, A. P results of second-order Raman-scattering experiments on hexagonal and cubic GaN covering the acoustic- boundary phonons in hexagonal GaN. S0163-1829 97 01812-2 I. INTRODUCTION The wide-band-gap semiconductor GaN

  2. Phonons in sapphire Al2O3 substrate for ZnO and GaN H.W. Kunert a,, A.G.J. Machatine b

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonons in sapphire Al2O3 substrate for ZnO and GaN H.W. Kunert a,, A.G.J. Machatine b , A. Keywords: Phonons; Sapphire; Group theory; Time reversal; Zno; GaN 1. Introduction The lattice structure in semiconductor research enabled fabrication of GaN-based blued emitting diodes and laser devices[1,2]. Due

  3. Electron-phonon superconductivity in LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}

    SciTech Connect (OSTI)

    Feng, Yanqing; Du, Yongping; Wan, Xiangang, E-mail: xgwan@nju.edu.cn; Wang, Bogen [Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Ding, Hang-Chen [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China); Savrasov, Sergey Y. [Department of Physics, University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Duan, Chun-Gang [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2014-06-21T23:59:59.000Z

    We report density functional calculations of the electronic structure, Fermi surface, phonon spectrum and electron–phonon coupling for the newly discovered superconductor LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}. It is confirmed that there is a strong Fermi surface nesting at (?,?,0), which results in unstable phonon branches. Combining the frozen phonon total energy calculations and an anharmonic oscillator model, we find that the quantum fluctuation prevents the appearance of static long–range order. The calculation shows that LaO{sub 0.5}F{sub 0.5}BiSe{sub 2} is highly anisotropic, and same as its cousin LaO{sub 0.5}F{sub 0.5}BiS{sub 2}, this compound is also a conventional electron-phonon coupling induced superconductor.

  4. Superlensing effect for surface acoustic waves in a pillar-based phononic crystal with negative refractive index

    SciTech Connect (OSTI)

    Addouche, Mahmoud, E-mail: mamoud.addouche@femto-st.fr; Al-Lethawe, Mohammed A., E-mail: mohammed.abdulridha@femto-st.fr; Choujaa, Abdelkrim, E-mail: achoujaa@femto-st.fr; Khelif, Abdelkrim, E-mail: abdelkrim.khelif@femto-st.fr [Institut FEMTO-ST, Université de Franche-Comté, CNRS, 32 Avenue de l'Observatoire, 25044 Besançon Cedex (France)

    2014-07-14T23:59:59.000Z

    We demonstrate super resolution imaging for surface acoustic waves using a phononic structure displaying negative refractive index. This phononic structure is made of a monolithic square lattice of cylindrical pillars standing on a semi-infinite medium. The pillars act as acoustic resonator and induce a surface propagating wave with unusual dispersion. We found, under specific geometrical parameters, one propagating mode that exhibits negative refraction effect with negative effective index close to ?1. Furthermore, a flat lens with finite number of pillars is designed to allow the focusing of an acoustic point source into an image with a resolution of (?)/3 , overcoming the Rayleigh diffraction limit.

  5. Lighting and Daylight Harvesting

    E-Print Network [OSTI]

    Bos, J.

    2011-01-01T23:59:59.000Z

    exposing us to the latest products and technologies. Daylight Harvesting A system of controlling the direction and the quantity of light both natural and artificial within a given space. This implies: Control of fenestration in terms of size..., transmission and direction. Control of reflected light within a space. Control of electric light in terms of delivery and amount Daylight harvesting systems are typically designed to maintain a minimum recommended light level. This light level...

  6. Solar Thermal Demonstration Project

    SciTech Connect (OSTI)

    Biesinger, K.; Cuppett, D.; Dyer, D.

    2012-01-30T23:59:59.000Z

    HVAC Retrofit and Energy Efficiency Upgrades at Clark High School, Las Vegas, Nevada The overall objectives of this project are to increase usage of alternative/renewable fuels, create a better and more reliable learning environment for the students, and reduce energy costs. Utilizing the grant resources and local bond revenues, the District proposes to reduce electricity consumption by installing within the existing limited space, one principal energy efficient 100 ton adsorption chiller working in concert with two 500 ton electric chillers. The main heating source will be primarily from low nitrogen oxide (NOX), high efficiency natural gas fired boilers. With the use of this type of chiller, the electric power and cost requirements will be greatly reduced. To provide cooling to the information technology centers and equipment rooms of the school during off-peak hours, the District will install water source heat pumps. In another measure to reduce the cooling requirements at Clark High School, the District will replace single pane glass and metal panels with â??Kalwallâ?? building panels. An added feature of the â??Kalwallâ? system is that it will allow for natural day lighting in the student center. This system will significantly reduce thermal heat/cooling loss and control solar heat gain, thus delivering significant savings in heating ventilation and air conditioning (HVAC) costs.

  7. EK101 Engineering Light Project: Evaluate Residential Lighting

    E-Print Network [OSTI]

    Bifano, Thomas

    EK101 Engineering Light Project: Evaluate Residential Lighting Compare technical and economic characteristics of three sources of residential light. Two teams of four complete the same project Engineering Light Project: Evaluate Residential Lighting Project Assignment: Evaluate current options

  8. Illumination of interior spaces by bended hollow light guides: Application of the theoretical light propagation method

    SciTech Connect (OSTI)

    Darula, Stanislav; Kocifaj, Miroslav; Kittler, Richard [ICA, Slovak Academy of Sciences, Bratislava (Slovakia); Kundracik, Frantisek [Department of Experimental Physics, FMPI, Comenius University, Bratislava (Slovakia)

    2010-12-15T23:59:59.000Z

    To ensure comfort and healthy conditions in interior spaces the thermal, acoustics and daylight factors of the environment have to be considered in the building design. Due to effective energy performance in buildings the new technology and applications also in daylight engineering are sought such as tubular light guides. These allow the transport of natural light into the building core reducing energy consumption. A lot of installations with various geometrical and optical properties can be applied in real buildings. The simplest set of tubular light guide consists of a transparent cupola, direct tube with high reflected inner surface and a ceiling cover or diffuser redistributing light into the interior. Such vertical tubular guide is often used on flat roofs. When the roof construction is inclined a bend in the light guide system has to be installed. In this case the cupola is set on the sloped roof which collects sunlight and skylight from the seen part of the sky hemisphere as well as that reflected from the ground and opposite facades. In comparison with the vertical tube some additional light losses and distortions of the propagated light have to be expected in bended tubular light guides. Recently the theoretical model of light propagation was already published and its applications are presented in this study solving illuminance distributions on the ceiling cover interface and further illuminance distribution on the working plane in the interior. (author)

  9. Role of phonon scattering by elastic strain field in thermoelectric Sr{sub 1?x}Y{sub x}TiO{sub 3??}

    SciTech Connect (OSTI)

    Bhattacharya, S., E-mail: bbhatta@clemson.edu, E-mail: ttritt@clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Mehdizadeh Dehkordi, A. [Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Tennakoon, S.; Adebisi, R.; Gladden, J. R. [Department of Physics and National Center for Physical Acoustics, University of Mississippi, University, Mississippi 38677 (United States); Darroudi, T. [Electron Microscope Facility, Clemson Research Park, Clemson University, Clemson, South Carolina 29625 (United States); Alshareef, H. N. [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tritt, T. M., E-mail: bbhatta@clemson.edu, E-mail: ttritt@clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States)

    2014-06-14T23:59:59.000Z

    Perovskite-type SrTiO{sub 3??} ceramics are multifunctional materials with significant potential as n-type thermoelectric (TE) materials. The electronic and thermal transport properties of spark plasma sintered polycrystalline Sr{sub 1?x}Y{sub x}TiO{sub 3??} (x?=?0.05, 0.075, 0.1) ceramics are systematically investigated from (15–800) K. The Sr{sub 0.9}Y{sub 0.1}TiO{sub 3??} simultaneously exhibits a large Seebeck coefficient, ??>??80??V/K and moderately high electrical resistivity, ????0.8?m?-cm at a carrier concentration of ?10{sup 21}?cm{sup ?3} at 300?K resulting in a high TE power factor defined herein as (?{sup 2}?T)???0.84?W/m-K at 760?K. Despite the similar atomic masses of Sr (87.6?g/mol) and Y (88.9?g/mol), the lattice thermal conductivity (?{sub L}) of Sr{sub 1?x}Y{sub x}TiO{sub 3??} is significantly reduced with increased Y-doping, owing to the smaller ionic radii of Y{sup 3+} (?1.23?Å, coordination number 12) compared to Sr{sup 2+} (?1.44?Å, coordination number 12) ions. In order to understand the thermal conductivity reduction mechanism, the ?{sub L} in the Sr{sub 1?x}Y{sub x}TiO{sub 3??} series are phenomenologically modeled with a modified Callaway's equation from 30–600?K. Phonon scattering by elastic strain field due to ionic radii mismatch is found to be the prominent scattering mechanism in reducing ?{sub L} of these materials. In addition, the effect of Y-doping on the elastic moduli of Sr{sub 1?x}Y{sub x}TiO{sub 3??} (x?=?0, 0.1) is investigated using resonant ultrasound spectroscopy, which exhibits an anomaly in x?=?0.1 in the temperature range 300–600?K. As a result, the phonon mean free path is found to be further reduced in the Sr{sub 0.9}Y{sub 0.1}TiO{sub 3??} compared to that of SrTiO{sub 3??}, resulting in a considerably low thermal conductivity ????2.7?W/m-K at 760?K. Finally, we report a thermoelectric figure of merit (ZT)???0.3 at 760?K in the Sr{sub 0.9}Y{sub 0.1}TiO{sub 3??}, the highest ZT value reported in the Y-doped SrTiO{sub 3} ceramics thus far.

  10. Trends in the electron-phonon coupling parameter in some metallic hydrides

    SciTech Connect (OSTI)

    Gupta, M.; Burger, J.P.

    1981-12-15T23:59:59.000Z

    We present an evaluation of the electron-phonon coupling parameter lambda, using the McMillan formalism, for several classes of stoichiometric mono- and dihydrides with a metallic underlying fcc structure. We calculate the electronic term eta and use experimental estimates for the phonon energies when available. We derive systematic trends concerning both contributions to eta stemming, respectively, from the metallic site M and the hydrogen site H. We show that eta/sub H/ is generally small, but it may become large if the Fermi energy is in the metal s-p band as in the filled d-band transition-metal (TM) hydrides such as PdH; eta/sub H/ may also be large when a metal-hydrogen antibonding band crosses the Fermi level, a case which happens in AlH and may happen for some unstable dihydrides. The metallic contribution eta/sub M/ is calculated to be small for all stable mono- and dihydrides like PdH, NiH, ZrH/sub 2/, NbH/sub 2/, etc., but nothing in principle prevents this contribution from becoming as large as in some pure TM, if one sweeps the Fermi level through the whole metallic d band. Good agreement with the available experimental data is obtained concerning the occurrence of superconductivity in the compounds considered.

  11. Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors

    SciTech Connect (OSTI)

    Moore, D. C.; Golwala, S. R.; Cornell, B. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125 (United States); Bumble, B.; Day, P. K.; LeDuc, H. G. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Zmuidzinas, J. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125 (United States); Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    2012-06-04T23:59:59.000Z

    We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors (MKIDs). The relative magnitude and delay of the signal received in each sensor allow the location of the interaction to be determined with < or approx. 1mm resolution at 30 keV. Using this position information, variations in the detector response with position can be removed, and an energy resolution of {sigma}{sub E} = 0.55 keV at 30 keV was measured. Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain, this technology can be extended to provide highly pixelized athermal phonon sensors for {approx}1 kg scale detector elements. Such high-resolution, massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter, neutrinoless double-beta decay, or coherent neutrino-nucleus scattering.

  12. Gutzwiller charge phase diagram of cuprates, including electron–phonon coupling effects

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

    Markiewicz, R. S.; Seibold, G.; Lorenzana, J.; Bansil, A.

    2015-02-01T23:59:59.000Z

    Besides significant electronic correlations, high-temperature superconductors also show a strong coupling of electrons to a number of lattice modes. Combined with the experimental detection of electronic inhomogeneities and ordering phenomena in many high-Tc compounds, these features raise the question as to what extent phonons are involved in the associated instabilities. Here we address this problem based on the Hubbard model including a coupling to phonons in order to capture several salient features of the phase diagram of hole-doped cuprates. Charge degrees of freedom, which are suppressed by the large Hubbard U near half-filling, are found to become active at amore »fairly low doping level. We find that possible charge order is mainly driven by Fermi surface nesting, with competition between a near-(?, ?) order at low doping and antinodal nesting at higher doping, very similar to the momentum structure of magnetic fluctuations. The resulting nesting vectors are generally consistent with photoemission and tunneling observations, evidence for charge density wave order in YBa?Cu?O7-? including Kohn anomalies, and suggestions of competition between one- and two-q-vector nesting.« less

  13. The importance of anharmonicity in thermal transport across solid-solid interfaces

    SciTech Connect (OSTI)

    Wu, Xufei [Aerospace and Mechanical Engineering, University of Notre Dame, 371 Fitzpatrick Hall-Notre Dame, Indiana 46556 (United States); Luo, Tengfei, E-mail: tluo@nd.edu [Aerospace and Mechanical Engineering, University of Notre Dame, 371 Fitzpatrick Hall-Notre Dame, Indiana 46556 (United States); Center for Sustainable Energy at Notre Dame, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2014-01-07T23:59:59.000Z

    Understanding interfacial thermal transport is of great importance for applications like energy devices and thermal management of electronics. Despite the significant efforts in the past few decades, thermal transport across solid-solid interfaces is still not fully understood and cannot be accurately predicted. Anharmonicity is often ignored in many prediction models, such as the mismatch models, the wave-packet method, and the Atomic Green's function. In this paper, we use molecular dynamics to systematically study the role of anharmonicity in thermal transport across solid-solid interfaces. The interatomic interactions are modeled using force constants up to the third order. This model allows controlling the anharmonicity independently by tuning the cubic force constants. The interfacial thermal conductance as a function of anharmonicity inside the materials and that at the interface is studied. We found that the anharmonicity inside the materials plays an important role in the interfacial thermal transport by facilitating the energy communication between different phonon modes. The anharmonicity at the interface has much less impact on the interfacial thermal transport. These results are important to the modification of traditional models to improve their prediction power.

  14. Thermal emission in the ultrastrong coupling regime

    E-Print Network [OSTI]

    A. Ridolfo; M. Leib; S. Savasta; M. J. Hartmann

    2012-10-08T23:59:59.000Z

    We study thermal emission of a cavity quantum electrodynamic system in the ultrastrong-coupling regime where the atom-cavity coupling rate becomes comparable the cavity resonance frequency. In this regime, the standard descriptions of photodetection and dissipation fail. Following an approach that was recently put forward by Ridolfo et al.[arXiv:1206.0944], we are able to calculate the emission of systems with arbitrary strength of light matter interaction, by expressing the electric field operator in the cavity-emitter dressed basis. Here we present thermal photoluminescence spectra, calculated for given temperatures and for different couplings in particular for available circuit QED parameters.

  15. HEATS: Thermal Energy Storage

    SciTech Connect (OSTI)

    None

    2012-01-01T23:59:59.000Z

    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.

  16. Thermal unobtainiums? The perfect thermal conductor and

    E-Print Network [OSTI]

    Braun, Paul

    conduction · Heat conduction in Bose condensates ­ electronic superconductors ­ superfluid helium ­ Bose condensate of magnons #12;Outline--toward perfect thermal insulators · Einstein and minimum thermal directions #12;Gas kinetic equation is a good place to start · Anharmonicity (high T limit) · Point defect

  17. Deficiencies of Lighting Codes and Ordinances in Controlling Light Pollution from Parking Lot Lighting Installations

    E-Print Network [OSTI]

    Royal, Emily

    2012-05-31T23:59:59.000Z

    The purpose of this research was to identify the main causes of light pollution from parking lot electric lighting installations and highlight the deficiencies of lighting ordinances in preventing light pollution. Using an industry-accepted lighting...

  18. Propagation of Lamb waves in one-dimensional quasiperiodic composite thin plates: A split of phonon band gap

    E-Print Network [OSTI]

    Li, Baowen

    Propagation of Lamb waves in one-dimensional quasiperiodic composite thin plates: A split of phonon the propagation of Lamb waves in one-dimensional quasiperiodic composite thin plates made of tungsten B spectra, Raman scattering spectra, and propagating modes of acoustic waves on corrugated surfaces.14

  19. PHYSICAL REVIEW B 88, 144307 (2013) Direct observation of the phonon dispersion of a three-dimensional solid/solid

    E-Print Network [OSTI]

    Deymier, Pierre

    2013-01-01T23:59:59.000Z

    Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA 4 Inorganic and ultrasonic phononic crystals.4,7­9 With the recent advances in material fabrication and characterization for solid/solid systems, very few attempts have been made to experimentally characterize dispersion

  20. Free electron properties of metals under ultrafast laser-induced electron-phonon nonequilibrium: a first-principles study

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Free electron properties of metals under ultrafast laser-induced electron-phonon nonequilibrium modelled based on the free electron classical theory, the free electron number is a key parameter. However or delocalized electronic states, temperature dependent free electron numbers are evaluated for a series

  1. OpenGL Lighting 13. OpenGL Lighting

    E-Print Network [OSTI]

    McDowell, Perry

    OpenGL Lighting 13. OpenGL Lighting · Overview of Lighting in OpenGL In order for lighting to have an effect in OpenGL, two things are required: A light An object to be lit Lights can be set to any color determine how they reflect the light which hits them. The color(s) of an object is determined

  2. Thermal Energy Storage

    SciTech Connect (OSTI)

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

    2013-06-05T23:59:59.000Z

    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.

  3. Adaptive Street Lighting Controls

    Broader source: Energy.gov [DOE]

    This two-part DOE Municipal Solid-State Street Lighting Consortium webinar focused on LED street lighting equipped with adaptive control components. In Part I, presenters Amy Olay of the City of...

  4. Sandia National Laboratories: Lighting

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

    Lighting Solid-State Lighting Science EFRC On November 11, 2010, in Welcome History of Incandescence History of LEDs Grand Challenges Our EFRC SSLS-EFRC Contacts News Publications...

  5. Electronic properties and electron-phonon coupling in zirconium and niobium hydrides

    SciTech Connect (OSTI)

    Gupta, M.

    1982-01-15T23:59:59.000Z

    The electronic structure of the two 4d transition-metal cubic dihydrides ZrH/sub 2/ and NbH/sub 2/ is investigated by means of an augmented-plane-wave (APW) band-structure calculation. The position of the Fermi level in a peak of the density of states (DOS) in the case of cubic ZrH/sub 2/ leads to an interpretation of the tetragonal distortion observed in all the group-IV transition-metal dihydrides in terms of a Jahn-Teller effect which lifts the degeneracy of the doubly degenerate band in the GAMMAL direction; these results are in agreement with magnetic susceptibility, electronic specific heat and thermoelectric power data. The main features of the DOS of the metal 4d states are similar for ZrH/sub 2/ and NbH/sub 2/, while the position and width of the low-lying bands are found to depend substantially upon the compound under study. These two bands which result from metal-hydrogen and hydrogen-hydrogen interactions overlap the metal d bands located at higher energies, contrary to the case of rare-earth dihydrides for which an energy gap was obtained. Our theoretical results are in good agreement with photoemission and x-ray emission spectra. We have evaluated the electron-phonon coupling constant lambda using the results of our APW calculation in conjunction with neutron scattering data. For both ZrH/sub 2/ and NbH/sub 2/, and contrary to the case of superconducting PdH, the electron-optical phonon contribution is small, due essentially to the low value of the DOS of s type at the H site at the Fermi energy and to the hardening of the optic modes. Moreover, the electronic term of the electron--acoustic-phonon contribution is reduced from its value in the pure metal. The two compounds are not found to be superconducting, in agreement with experimental results.

  6. Holographic thermalization and gravitational collapse in the spacetime dominated by quintessence dark energy

    E-Print Network [OSTI]

    Xiao-Xiong Zeng; De-You Chen; Li-Fang Li

    2014-12-21T23:59:59.000Z

    In this paper, the thermalization has been studied holographically. Explicitly in the gravity side, we consider the gravitational collapse of a thin shell of dust in a spacetime dominated by quintessence dark energy. With the thermalization probes such as the normalized geodesic length and minimal area surface, we study the effect of the state parameter for the quintessence dark energy on the thermalization. Our results show that the smaller the state parameter of quintessence is, the harder the plasma to thermalize. We also investigate the thermalization velocity and thermalization acceleration. We hope our results here can shed light on the nature of the quintessence dark energy.

  7. 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

  8. Thermal Performance Benchmarking (Presentation)

    SciTech Connect (OSTI)

    Moreno, G.

    2014-11-01T23:59:59.000Z

    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.

  9. Thermal neutron detection system

    DOE Patents [OSTI]

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

    2000-01-01T23:59:59.000Z

    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.

  10. Light emitting device comprising phosphorescent materials for white light generation

    DOE Patents [OSTI]

    Thompson, Mark E.; Dapkus, P. Daniel

    2014-07-22T23:59:59.000Z

    The present invention relates to phosphors for energy downconversion of high energy light to generate a broadband light spectrum, which emit light of different emission wavelengths.

  11. Advanced Demand Responsive Lighting

    E-Print Network [OSTI]

    Advanced Demand Responsive Lighting Host: Francis Rubinstein Demand Response Research Center demand responsive lighting systems ­ Importance of dimming ­ New wireless controls technologies · Advanced Demand Responsive Lighting (commenced March 2007) #12;Objectives · Provide up-to-date information

  12. Light Rail Transit Strengthening

    E-Print Network [OSTI]

    Minnesota, University of

    Light Rail Transit Improving mobility Easing congestion Strengthening our communities Central Corridor Communicating to the Public During Major Construction May 25, 2011 #12;2 Light Rail Transit;Light Rail Transit Central Corridor Route and Stations 3 · 18 new stations · 9.8 miles of new double

  13. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect (OSTI)

    Jamil A. Khan

    2009-11-21T23:59:59.000Z

    Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

  14. Thermal and non-thermal leptogenesis in different neutrino mass models with tribimaximal mixings

    E-Print Network [OSTI]

    N. Nimai Singh; H. Zeen Devi; Amal Kr Sarma

    2008-07-15T23:59:59.000Z

    In the present work we study both thermal and non-thermal leptogenesis in all neutrino mass models describing the presently available neutrino mass patterns. We consider the Majorana CP violating phases coming from right-handed Majorana mass matrices to estimate the baryon asymmetry of the universe, for different neutrino mass models namely degenerate, inverted hierarchical and normal hierarchical models, with tribimaximal mixings. Considering two possible diagonal forms of Dirac neutrino mass matrix as either charged lepton or up-quark mass matrix, the right-handed Majorana mass matrices are constructed from the light neutrino mass matrix through the inverse seesaw formula. Only the normal hierarchical model leads to the best predictions for baryon asymmetry of the universe, consistent with observations in both thermal and non-thermal leptogenesis scenario. The analysis though phenomenological may serve as an additional information in the discrimination among the presently available neutrino mass models.

  15. Optical phonon modes in InGaN/GaN dot-in-a-wire heterostructures grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Titus, J.; Perera, A. G. U. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Nguyen, H. P. T.; Mi, Z. [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)] [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)

    2013-03-25T23:59:59.000Z

    We report on the studies of optical phonon modes in nearly defect-free GaN nanowires embedded with intrinsic InGaN quantum dots by using oblique angle transmission infrared spectroscopy. These phonon modes are dependent on the nanowire fill-factor, doping densities of the nanowires, and the presence of InGaN dots. These factors can be applied for potential phonon based photodetectors whose spectral responses can be tailored by varying a combination of these three parameters. The optical anisotropy along the growth (c-) axis of the GaN nanowire contributes to the polarization agility of such potential photodetectors.

  16. Low-phonon-frequency chalcogenide crystalline hosts for rare earth lasers operating beyond three microns

    DOE Patents [OSTI]

    Payne, Stephen A. (Castro Valley, CA); Page, Ralph H. (San Ramon, CA); Schaffers, Kathleen I. (Pleasanton, CA); Nostrand, Michael C. (Livermore, CA); Krupke, William F. (Pleasanton, CA); Schunemann, Peter G. (Malden, MA)

    2000-01-01T23:59:59.000Z

    The invention comprises a RE-doped MA.sub.2 X.sub.4 crystalline gain medium, where M includes a divalent ion such as Mg, Ca, Sr, Ba, Pb, Eu, or Yb; A is selected from trivalent ions including Al, Ga, and In; X is one of the chalcogenide ions S, Se, and Te; and RE represents the trivalent rare earth ions. The MA.sub.2 X.sub.4 gain medium can be employed in a laser oscillator or a laser amplifier. Possible pump sources include diode lasers, as well as other laser pump sources. The laser wavelengths generated are greater than 3 microns, as becomes possible because of the low phonon frequency of this host medium. The invention may be used to seed optical devices such as optical parametric oscillators and other lasers.

  17. High-frequency homogenization of zero frequency stop band photonic and phononic crystals

    E-Print Network [OSTI]

    Antonakakis, Tryfon; Guenneau, Sebastien

    2013-01-01T23:59:59.000Z

    We present an accurate methodology for representing the physics of waves, for periodic structures, through effective properties for a replacement bulk medium: This is valid even for media with zero frequency stop-bands and where high frequency phenomena dominate. Since the work of Lord Rayleigh in 1892, low frequency (or quasi-static) behaviour has been neatly encapsulated in effective anisotropic media. However such classical homogenization theories break down in the high-frequency or stop band regime. Higher frequency phenomena are of significant importance in photonics (transverse magnetic waves propagating in infinite conducting parallel fibers), phononics (anti-plane shear waves propagating in isotropic elastic materials with inclusions), and platonics (flexural waves propagating in thin-elastic plates with holes). Fortunately, the recently proposed high-frequency homogenization (HFH) theory is only constrained by the knowledge of standing waves in order to asymptotically reconstruct dispersion curves an...

  18. Optical and phonon properties of ZnO:CuO mixed nanocomposite

    SciTech Connect (OSTI)

    Udayabhaskar, R.; Karthikeyan, B., E-mail: bkarthik@nitt.edu [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2014-04-21T23:59:59.000Z

    Optical and phonon properties of ZnO:CuO nanocrystals which are prepared through sol-gel method are reported here. From X-ray diffraction studies, observed that Cu doping replaces the Zn and also forms secondary phase. Optical absorption spectral studies shows that the exciton and plasmon related bands of ZnO and CuO phase, respectively. Fluorescence studies of the prepared samples shows that green emission from ZnO is completely depleted and the same is attributed to CuO Plasmon. Raman spectral studies reveal that secondary phase (impurity) induced profile changes in 1LO and E{sub 2High} modes. Asymmetry in peak shape is analyzed using Fano profile with the combination of Lorentzian profile. Moreover, the monotonic increase of Fano factor and full width at half maxima is hopefully attributed to the continuum arises by the plasmons of Cu-O phase in ZnO nanosystem.

  19. Phononic pairing glue in cuprates and related high-temperature superconductors

    E-Print Network [OSTI]

    A. S. Alexandrov

    2011-12-16T23:59:59.000Z

    Along with some other researches we have realised that the true origin of high-temperature superconductivity should be found in the strong Coulomb repulsion combined with a significant electronphonon interaction. Both interactions are strong (on the order of 1 eV) compared with the low Fermi energy of doped carries which makes the conventional BCS-Eliashberg theory inapplicable in cuprates and related doped insulators. Based on our recent analytical and numerical results I argue that high-temperature superconductivity from repulsion is impossible for any strength of the Coulomb interaction. Major steps of our alternative polaronic theory are outlined starting from the generic Hamiltonian with the unscreened (bare) Coulomb and electron-phonon interactions accounting for critical temperatures of high-temperature superconductors without any adjustable parameters.

  20. Resonant energy transfer enhanced by off-diagonal exciton-phonon coupling

    E-Print Network [OSTI]

    Ning Wu; Zhe Chang; Yang Zhao

    2011-08-03T23:59:59.000Z

    Dynamics of resonant energy transfer of a single excitation in a molecular dimer system is studied in the simultaneous presence of diagonal and off-diagonal exciton-phonon coupling. It is found that the off-diagonal coupling plays an important role in the excitation energy transfer process. Coherent transfer can be found at arbitrary temperature for a non-vanishing off-diagonal coupling strength with an oscillation frequency of site populations that increases with the off-diagonal coupling strength. Furthermore, we identify a threshold of the off-diagonal coupling strength below which there exists an optimal temperature that maximizes the total population transfer from the initially excited monomer to the acceptor monomer at long times. As the off-diagonal coupling strength is increased beyond the threshold, however, the optimal temperature is found to abruptly drop to zero.

  1. Phonon spectrum of QCD vacuum in magnetic-field-induced superconducting phase

    E-Print Network [OSTI]

    M. N. Chernodub; Jos Van Doorsselaere; Henri Verschelde

    2014-06-16T23:59:59.000Z

    In the background of a sufficiently strong magnetic field the vacuum was suggested to become an ideal electric conductor (highly anisotropic superconductor) due to an interplay between the strong and electromagnetic forces. The superconducting ground state resembles an Abrikosov lattice state in an ordinary type--II superconductor: it is an inhomogeneous structure made of a (charged vector) quark-antiquark condensate pierced by vortices. In this paper the acoustic (phonon) vibrational modes of the vortex lattice are studied at zero temperature. Using an effective model based on a vector meson dominance, we show that in the infrared limit the longitudinal (transverse) acoustic vibrations of the vortex lattice possess a linear (quadratic) dispersion relation corresponding to type I (type II) Nambu--Goldstone modes.

  2. Phonon properties of BaFe?X? (X=S, Se) spin ladder compounds

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

    Popovicq, Z. V.; Petrovic, C.; Scepanovic, M.; Lazarevic, N.; Opacic, M.; Radonjic, M. M.; Tanaskovic, D.; Lei, Hechang

    2015-02-01T23:59:59.000Z

    We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe?X? (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe?S? (BaFe?Se?) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe?S(Se)? is supported by themore »lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe?Se? below TN=255K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.« less

  3. Low-Temperature Light Detectors: Neganov-Luke Amplification and Calibration

    E-Print Network [OSTI]

    C. Isaila; C. Ciemniak; F. v. Feilitzsch; A. Gütlein; J. Kemmer; T. Lachenmaier; J. -C. Lanfranchi; S. Pfister; W. Potzel; S. Roth; M. v. Sivers; R. Strauss; W. Westphal; F. Wiest

    2012-09-17T23:59:59.000Z

    The simultaneous measurement of phonons and scintillation light induced by incident particles in a scintillating crystal such as CaWO4 is a powerful technique for the active rejection of background induced by gamma's and beta's and even neutrons in direct Dark Matter searches. However, less than ~1% of the energy deposited in a CaWO4 crystal is detected as light. Thus, very sensitive light detectors are needed for an efficient event-by-event background discrimination. Due to the Neganov-Luke effect, the threshold of low-temperature light detectors based on semiconducting substrates can be improved significantly by drifting the photon-induced electron-hole pairs in an applied electric field. We present measurements with low-temperature light detectors based on this amplification mechanism. The Neganov-Luke effect makes it possible to improve the signal-to-noise ratio of our light detectors by a factor of ~9 corresponding to an energy threshold of ~21 eV. We also describe a method for an absolute energy calibration using a light-emitting diode.

  4. Light extraction from organic light-emitting diodes for lighting applications by sand-blasting

    E-Print Network [OSTI]

    Light extraction from organic light-emitting diodes for lighting applications by sand@ust.hk Abstract: Light extraction from organic light-emitting diodes (OLEDs) by scattering the light is one of the effective methods for large-area lighting applications. In this paper, we present a very simple and cost

  5. Photonic crystal light source

    DOE Patents [OSTI]

    Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Bur, James A. (Corrales, NM)

    2004-07-27T23:59:59.000Z

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  6. Thermal and Electric Conductivities of Coulomb Crystals in Neutron Stars and White Dwarfs

    E-Print Network [OSTI]

    D. A. Baiko; D. G. Yakovlev

    1996-04-28T23:59:59.000Z

    Thermal and electric conductivities are calculated for degenerate electrons scattered by phonons in a crystal made of atomic nuclei. The exact phonon spectrum and the Debye--Waller factor are taken into account. Monte Carlo calculations are performed for body-centered cubic (bcc) crystals made of C, O, Ne, Mg, Si, S, Ca, and Fe nuclei in the density range from $10^3$ to $10^{11}$ g cm$^{-3}$ at temperatures lower than the melting temperature but higher than the temperature at which the Umklapp processes begin to be "frozen out". A simplified method of calculation is proposed, which makes it possible to describe the results in terms of simple analytic expressions, to extend these expressions to any species of nucleus, and to consider face-centered cubic (fcc) crystals. The kinetic coefficients are shown to depend tangibly on the lattice type. The results are applicable to studies of heat transfer and evolution of the magnetic field in the cores of white dwarfs and in the crusts of neutron stars. The thermal drift of the magnetic field in the crust of a neutron star is discussed.

  7. Influence of longitudinal isotope substitution on the thermal conductivity of carbon nanotubes: Results of nonequilibrium molecular dynamics and local density functional calculations

    SciTech Connect (OSTI)

    Leroy, Frédéric, E-mail: f.leroy@theo.chemie.tu-darmstadt.de; Böhm, Michael C., E-mail: boehm@theo.chemie.tu-darmstadt.de [Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt (Germany); Schulte, Joachim [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany)] [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany); Balasubramanian, Ganesh [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-04-14T23:59:59.000Z

    We report reverse nonequilibrium molecular dynamics calculations of the thermal conductivity of isotope substituted (10,10) carbon nanotubes (CNTs) at 300 K. {sup 12}C and {sup 14}C isotopes both at 50% content were arranged either randomly, in bands running parallel to the main axis of the CNTs or in bands perpendicular to this axis. It is found that the systems with randomly distributed isotopes yield significantly reduced thermal conductivity. In contrast, the systems where the isotopes are organized in patterns parallel to the CNTs axis feature no reduction in thermal conductivity when compared with the pure {sup 14}C system. Moreover, a reduction of approximately 30% is observed in the system with the bands of isotopes running perpendicular to the CNT axis. The computation of phonon dispersion curves in the local density approximation and classical densities of vibrational states reveal that the phonon structure of carbon nanotubes is conserved in the isotope substituted systems with the ordered patterns, yielding high thermal conductivities in spite of the mass heterogeneity. In order to complement our conclusions on the {sup 12}C-{sup 14}C mixtures, we computed the thermal conductivity of systems where the {sup 14}C isotope was turned into pseudo-atoms of 20 and 40 atomic mass units.

  8. Intensity-Intensity Correlations of Classically Entangled Light

    E-Print Network [OSTI]

    Partha Ghose; Anirban Mukherjee

    2014-01-03T23:59:59.000Z

    An experiment is proposed to show that after initial frequency and polarization selection, classical thermal light from two independent sources can be made path-polarization entangled. Such light will show new intensity-intensity correlations involving both path and polarization phases, formally similar to those for four-particle GHZ states. For fixed polarization phases, the correlations reduce to the Hanbury Brown-Twiss phase correlations. It is also shown that these classical correlations violate noncontextuality.

  9. Foundations and Light Compass Foundations and Light Compass

    E-Print Network [OSTI]

    Wong, Jennifer L.

    Foundations and Light Compass Case Study Foundations and Light Compass Case Study Jennifer L. WongQuantitative Sensor--centric Designcentric Design Light CompassLight Compass ­­ Models and Abstractions Contaminant Transport Marine Microorganisms Ecosystems, Biocomplexity What is a Light Compass?What is a Light

  10. Lighting and Surfaces 11.1 Introduction to Lighting

    E-Print Network [OSTI]

    Boyd, John P.

    Chapter 11 Lighting and Surfaces 11.1 Introduction to Lighting Three-dimensional surfaces can react to light, and how computer graphics simulates this. There are three species of light (or "illumination models"): 1. Intrinsic (self-emitting) 2. Ambient light (sometimes called "diffuse light") 3

  11. Optical, vibrational, thermal, electrical, damage and phase-matching properties of lithium thioindate

    E-Print Network [OSTI]

    Fossier, S; Mangin, J F; Bidault, O; Thnot, I; Zondy, J J; Chen, W; Rotermund, F; Petrov, V; Petrov, P; Henningsen, J; Yelisseyev, A; Isaenko, L; Lobanov, S; Balachninaite, O; Slekys, G; Sirutkaitis, V; Zelt, S

    2003-01-01T23:59:59.000Z

    Lithium thioindate (LiInS$_{2}$) is a new nonlinear chalcogenide bi-axial material transparent from 0.4 to 12 $\\mu$m, that has been successfully grown in large sizes and good optical quality. As a result of a three-year intensive characterization campaign of its main properties, we report new and updated physical parameters that are relevant for laser and nonlinear optics applications: lattice phonon vibrational spectra, thermal expansion and thermo-optic coefficients, specific heat at constant pressure, thermal conductivity, piezo-electric and electro-optic coefficients, laser damage thresholds, accurate optical linear dispersion and nonlinear second-order susceptibility coefficients. We provide also a detailed study of the in and out-of-principal plane phase-matching characteristics and associated effective nonlinear coefficients. New experimental results on direct mid-IR (5 - $12 \\mu$m) down-conversion (femtosecond parametric amplification and continuous-wave (cw) difference-frequency generation) pumped by...

  12. Arnold Schwarzenegger LIGHTING RESEARCH PROGRAM

    E-Print Network [OSTI]

    Project Summaries ELEMENT 2: ADVANCE LIGHTING TECHNOLOGIES PROJECT 2.1 LIGHT EMITTING DIODE (LED light emitting diodes (LED) technology for general lighting applications by developing a task lamp

  13. Lattice Thermal conductivity of the Cu3SbSe4-Cu3SbS4 Solid Solution

    SciTech Connect (OSTI)

    Skoug, Eric [Michigan State University, East Lansing; Cain, Jeffrey D. [Michigan State University, East Lansing; Morelli, Donald [Michigan State University, East Lansing; Kirkham, Melanie J [ORNL; Majsztrik, Paul W [ORNL; Lara-Curzio, Edgar [ORNL

    2011-01-01T23:59:59.000Z

    The compositional dependence of the crystal structure and lattice thermal conductivity in the Cu3SbSe4-Cu3SbS4 system has been studied. The lattice parameters of the Cu3SbSe4-xSx compounds decrease linearly with x, and the tetragonal structure (space group no. 121) of the end compounds is maintained at all compositions. The thermal conductivity is much lower than that predicted by a simple rule of mixtures, which is typical for a solid solution. The Debye model produces a very reasonable fit to the experimental lattice thermal conductivity data when phonon scattering due to atomic mass and size differences between Se and S is taken into account. Compounds in this series are likely to improve upon the thermoelectric performance of Cu3SbSe4, which has shown ZT=0.72 when optimized.

  14. Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect (OSTI)

    Narumanchi, S.

    2013-07-01T23:59:59.000Z

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  15. Light-Weight, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect (OSTI)

    Narumanchi, S.

    2013-07-01T23:59:59.000Z

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  16. Taunton Municipal Lighting Plant- Residential and Non-Profit Weatherization Program (Massachusetts)

    Broader source: Energy.gov [DOE]

    Taunton Municipal Lighting Plant (TMLP) offers the 'House N Home' Thermal Rebate Program which provides financial incentives to residential and non-Profit customers for making buildings more energy...

  17. National Synchrotron Light Source

    ScienceCinema (OSTI)

    BNL

    2009-09-01T23:59:59.000Z

    A tour of Brookhaven's National Synchrotron Light Source (NSLS), hosted by Associate Laboratory Director for Light Sources, Stephen Dierker. The NSLS is one of the world's most widely used scientific research facilities, hosting more than 2,500 guest researchers each year. The NSLS provides intense beams of infrared, ultraviolet, and x-ray light for basic and applied research in physics, chemistry, medicine, geophysics, environmental, and materials sciences.

  18. LED Lighting Retrofit

    E-Print Network [OSTI]

    Shaw-Meadow, N.

    2011-01-01T23:59:59.000Z

    ? Municipal Street Lighting Consortium ? American Public Power Association (APPA) ? Demonstration in Energy Efficiency Development (DEED) ? Source of funding and database of completed LED roadway projects 6 Rules of the Road ESL-KT-11-11-57 CATEE 2011..., 2011 ? 9 Solar-Assisted LED Case Study LaQuinta Hotel, Cedar Park, Texas ? Utilizes 18 - ActiveLED Solar-Assisted Parking Lot Lights ? Utilizes ?power management? to extend battery life while handling light output ? Reduces load which reduces PV...

  19. Interfacial electron and phonon scattering processes in high-powered nanoscale applications.

    SciTech Connect (OSTI)

    Hopkins, Patrick E.

    2011-10-01T23:59:59.000Z

    The overarching goal of this Truman LDRD project was to explore mechanisms of thermal transport at interfaces of nanomaterials, specifically linking the thermal conductivity and thermal boundary conductance to the structures and geometries of interfaces and boundaries. Deposition, fabrication, and post possessing procedures of nanocomposites and devices can give rise to interatomic mixing around interfaces of materials leading to stresses and imperfections that could affect heat transfer. An understanding of the physics of energy carrier scattering processes and their response to interfacial disorder will elucidate the potentials of applying these novel materials to next-generation high powered nanodevices and energy conversion applications. An additional goal of this project was to use the knowledge gained from linking interfacial structure to thermal transport in order to develop avenues to control, or 'tune' the thermal transport in nanosystems.

  20. Edmund G. Brown Jr. LIGHTING CALIFORNIA'S FUTURE

    E-Print Network [OSTI]

    Edmund G. Brown Jr. Governor LIGHTING CALIFORNIA'S FUTURE: SMART LIGHT-EMITTING DIODE LIGHTING's Future: Smart LightEmitting Diode Lighting in Residential Fans. California Energy Commission, PIER

  1. Thermal Infrared Remote Sensing

    E-Print Network [OSTI]

    Thermal Infrared Remote Sensing Thermal Infrared Remote Sensing #12;0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4 and x-ray Ultraviolet Infrared Microwave and radio waves Wavelength in meters (m) Electromagnetic.77 700 red limit 30k0.041 2.48 green500 near-infrared far infrared ultraviolet Thermal Infrare refers

  2. Comparing Light Bulbs

    Broader source: Energy.gov [DOE]

    In this exercise, students will use a light to demonstrate the difference between being energy-efficient and energy-wasteful, and learn what energy efficiency means.

  3. Total Light Management

    Broader source: Energy.gov [DOE]

    Presentation covers total light management, and is given at the Spring 2010 Federal Utility Partnership Working Group (FUPWG) meeting in Providence, Rhode Island.

  4. Lighting Technology Panel

    Broader source: Energy.gov [DOE]

    Presentation covers the Lighting Technology Panel for the Federal Utility Partnership Working Group (FUPWG) meeting, held on November 18-19, 2009. 

  5. Hybrid Solar Lighting

    SciTech Connect (OSTI)

    Maxey, L Curt [ORNL

    2008-01-01T23:59:59.000Z

    Hybrid solar lighting systems focus highly concentrated sunlight into a fiber optic bundle to provide sunlight in rooms without windows or conventional skylights.

  6. Solid-State Lighting

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

    into the market. On the market side, DOE works closely with drivers, heat sinks, and optics. LEDs must be carefully energy efficiency program partners, lighting professionals,...

  7. AQUIFER THERMAL ENERGY STORAGE

    E-Print Network [OSTI]

    Tsang, C.-F.

    2011-01-01T23:59:59.000Z

    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

  8. Scattering Solar Thermal Concentrators

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

    eere.energy.gov * energy.govsunshot DOEGO-102012-3669 * September 2012 MOTIVATION All thermal concentrating solar power (CSP) systems use solar tracking, which involves moving...

  9. Advanced Thermal Control

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

    Potential Thermal Control Technologies Advanced Vehicle Systems Technology Transfer Jet Cooling Alternative Coolants TIM Low R Structure Phase Change Spray Cooling Air Cooling...

  10. Physics of band-gap formation and its evolution in the pillar-based phononic crystal structures

    SciTech Connect (OSTI)

    Pourabolghasem, Reza; Mohammadi, Saeed; Eftekhar, Ali Asghar; Adibi, Ali [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Khelif, Abdelkrim [Institut FEMTO-ST, Université de Franche-Comté, CNRS, 32 Avenue de l'Observatoire, 25044 Besançon Cedex (France)

    2014-07-07T23:59:59.000Z

    In this paper, the interplay of Bragg scattering and local resonance is theoretically studied in a phononic crystal (PnC) structure composed of a silicon membrane with periodic tungsten pillars. The comparison of phononic band gaps (PnBGs) in three different lattice types (i.e., square, triangular, and honeycomb) with different pillar geometries shows that different PnBGs have varying degrees of dependency on the lattice symmetry based on the interplay of the local resonances and the Bragg effect. The details of this interplay is discussed. The significance of locally resonating pillars, specially in the case of tall pillars, on PnBGs is discussed and verified by examining the PnBG position and width in perturbed lattices via Monte Carlo simulations. It is shown that the PnBGs caused by the local resonance of the pillars are more resilient to the lattice perturbations than those caused by Bragg scattering.

  11. Nuclear Thermal Propulsion: A Joint NASA/DOE/DOD Workshop

    SciTech Connect (OSTI)

    Clark, J.S.

    1991-01-01T23:59:59.000Z

    Papers presented at the joint NASA/DOE/DOD workshop on nuclear thermal propulsion are compiled. The following subject areas are covered: nuclear thermal propulsion programs; Rover/NERVA and NERVA systems; Low Pressure Nuclear Thermal Rocket (LPNTR); particle bed reactor nuclear rocket; hybrid propulsion systems; wire core reactor; pellet bed reactor; foil reactor; Droplet Core Nuclear Rocket (DCNR); open cycle gas core nuclear rockets; vapor core propulsion reactors; nuclear light bulb; Nuclear rocket using Indigenous Martian Fuel (NIMF); mission analysis; propulsion and reactor technology; development plans; and safety issues.

  12. Variable pressure thermal insulating jacket

    DOE Patents [OSTI]

    Nelson, P.A.; Malecha, R.F.; Chilenskas, A.A.

    1994-09-20T23:59:59.000Z

    A device for controlled insulation of a thermal device is disclosed. The device includes a thermal jacket with a closed volume able to be evacuated to form an insulating jacket around the thermal source. A getter material is in communication with the closed volume of the thermal jacket. The getter material can absorb and desorb a control gas to control gas pressure in the volume of the thermal jacket to control thermal conductivity in the thermal jacket. 10 figs.

  13. The thermal performance of fixed and variable selective transmitters in commercial architecture

    E-Print Network [OSTI]

    Bartovics, William A

    1984-01-01T23:59:59.000Z

    A parametric model is developed for use in evaluating the relative thermal and lighting performance of a variety of existing and proposed types of commercial glazing materials. The glazing materials considered are divided ...

  14. The high conductivity of iron and thermal evolution of the Earth's core Hitoshi Gomi a,

    E-Print Network [OSTI]

    with secular cooling (along with possible radioactive heating) and buoy- ant release of incompatible light, if thermal buoyancy alone drives convection, then the power for maintaining a geodynamo must be in excess

  15. NEUTRONIC AND THERMAL HYDRAULIC DESIGNS OF ANNULAR FUEL FOR HIGH POWER DENSITY BWRS

    E-Print Network [OSTI]

    Morra, P.

    As a promising new fuel for high power density light water reactors, the feasibility of using annular fuel for BWR services is explored from both thermal hydraulic and neutronic points of view. Keeping the bundle size ...

  16. Phonon mediated spin relaxation in a moving quantum dot: Doppler shift, Cherenkov radiation, and spin relaxation boom

    E-Print Network [OSTI]

    Xinyu Zhao; Peihao Huang; Xuedong Hu

    2015-02-27T23:59:59.000Z

    We study relaxation of a moving spin qubit caused by phonon noise. As we vary the speed of the qubit, we observe several interesting features in spin relaxation and the associated phonon emission, induced by Doppler effect. In particular, in the supersonic regime, the phonons emitted by the relaxing qubit is concentrated along certain directions, similar to the shock waves produced in classical Cherenkov effect. As the speed of the moving qubit increases from the subsonic regime to the supersonic regime, the qubit experiences a peak in the spin relaxation rate near the speed of sound, which we term a spin relaxation boom in analogy to the classical sonic boom. We also find that the moving spin qubit may have a lower relaxation rate than a static qubit, which hints at the possibility of coherence-preserving transportation for a spin qubit. While the physics we have studied here has strong classical analogies, we do find that quantum confinement for the spin qubit plays an important role in all the phenomena we observe. Specifically, it produces a correction on the Cherenkov angle, and removes the divergence in relaxation rate at the sonic barrier. It is our hope that our results would encourage further research into approaches for transferring and preserving quantum information in spin qubit architectures.

  17. Gallium nanoparticles grow where light is

    E-Print Network [OSTI]

    K. F. MacDonald; W. S. Brocklesby; V. I. Emelyanov; V. A. Fedotov; S. Pochon; K. J. Ross; G. Stevens; N. I. Zheludev

    2001-05-15T23:59:59.000Z

    The study of metallic nanoparticles has a long tradition in linear and nonlinear optics [1], with current emphasis on the ultrafast dynamics, size, shape and collective effects in their optical response [2-6]. Nanoparticles also represent the ultimate confined geometry:high surface-to-volume ratios lead to local field enhancements and a range of dramatic modifications of the material's properties and phase diagram [7-9]. Confined gallium has become a subject of special interest as the light-induced structural phase transition recently observed in gallium films [10, 11] has allowed for the demonstration of all-optical switching devices that operate at low laser power [12]. Spontaneous self-assembly has been the main approach to the preparation of nanoparticles (for a review see 13). Here we report that light can dramatically influence the nanoparticle self-assembly process: illumination of a substrate exposed to a beam of gallium atoms results in the formation of nanoparticles with a relatively narrow size distribution. Very low light intensities, below the threshold for thermally-induced evaporation, exert considerable control over nanoparticle formation through non-thermal atomic desorption induced by electronic excitation.

  18. Reducing home lighting expenses

    SciTech Connect (OSTI)

    Aimone, M.A.

    1981-02-01T23:59:59.000Z

    Ways to reduce lighting expenses are summarized. These include: turning off lights when not in use; keeping fixtures and lamps clean; replacing lamps with more efficient types; using three-way bulbs; use of daylighting; buying fewer lamps and reducing lamp wattage; consider repainting rooms; replacing recessed fixtures with tracklighting; and using efficient lamps for outdoor use. (MCW)

  19. Explosively pumped laser light

    DOE Patents [OSTI]

    Piltch, Martin S. (Los Alamos, NM); Michelotti, Roy A. (Los Alamos, NM)

    1991-01-01T23:59:59.000Z

    A single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.

  20. Light intensity compressor

    DOE Patents [OSTI]

    Rushford, Michael C. (Livermore, CA)

    1990-01-01T23:59:59.000Z

    In a system for recording images having vastly differing light intensities over the face of the image, a light intensity compressor is provided that utilizes the properties of twisted nematic liquid crystals to compress the image intensity. A photoconductor or photodiode material that is responsive to the wavelength of radiation being recorded is placed adjacent a layer of twisted nematic liquid crystal material. An electric potential applied to a pair of electrodes that are disposed outside of the liquid crystal/photoconductor arrangement to provide an electric field in the vicinity of the liquid crystal material. The electrodes are substantially transparent to the form of radiation being recorded. A pair of crossed polarizers are provided on opposite sides of the liquid crystal. The front polarizer linearly polarizes the light, while the back polarizer cooperates with the front polarizer and the liquid crystal material to compress the intensity of a viewed scene. Light incident upon the intensity compressor activates the photoconductor in proportion to the intensity of the light, thereby varying the field applied to the liquid crystal. The increased field causes the liquid crystal to have less of a twisting effect on the incident linearly polarized light, which will cause an increased percentage of the light to be absorbed by the back polarizer. The intensity of an image may be compressed by forming an image on the light intensity compressor.

  1. Gallium ion implantation greatly reduces thermal conductivity and enhances electronic one of ZnO nanowires

    SciTech Connect (OSTI)

    Xia, Minggang, E-mail: xiamg@mail.xjtu.edu.cn [Laboratory of Nanostructure and its Physics Properties, Department of Optical Information Science and Technology, Department of Applied Physics, and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 China (China); Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Cheng, Zhaofang; Han, Jinyun; Zhang, Shengli [Laboratory of Nanostructure and its Physics Properties, Department of Optical Information Science and Technology, Department of Applied Physics, and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 China (China); Zheng, Minrui [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); Sow, Chorng-Haur [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); National University of Singapore Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117542 (Singapore); Thong, John T. L. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Li, Baowen [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); National University of Singapore Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117542 (Singapore); Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

    2014-05-15T23:59:59.000Z

    The electrical and thermal conductivities are measured for individual zinc oxide (ZnO) nanowires with and without gallium ion (Ga{sup +}) implantation at room temperature. Our results show that Ga{sup +} implantation enhances electrical conductivity by one order of magnitude from 1.01 × 10{sup 3} ?{sup ?1}m{sup ?1} to 1.46 × 10{sup 4} ?{sup ?1}m{sup ?1} and reduces its thermal conductivity by one order of magnitude from 12.7 Wm{sup ?1}K{sup ?1} to 1.22 Wm{sup ?1}K{sup ?1} for ZnO nanowires of 100 nm in diameter. The measured thermal conductivities are in good agreement with those in theoretical simulation. The increase of electrical conductivity origins in electron donor doping by Ga{sup +} implantation and the decrease of thermal conductivity is due to the longitudinal and transverse acoustic phonons scattering by Ga{sup +} point scattering. For pristine ZnO nanowires, the thermal conductivity decreases only two times when its diameter reduces from 100 nm to 46 nm. Therefore, Ga{sup +}-implantation may be a more effective method than diameter reduction in improving thermoelectric performance.

  2. Thermal protection apparatus

    DOE Patents [OSTI]

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

    1985-01-01T23:59:59.000Z

    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.

  3. Thermal protection apparatus

    DOE Patents [OSTI]

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

    1984-03-20T23:59:59.000Z

    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.

  4. Lighting affects appearance LightSource emits photons

    E-Print Network [OSTI]

    Jacobs, David

    1 Lighting affects appearance #12;2 LightSource emits photons Photons travel in a straight line). And then some reach the eye/camera. #12;3 Reflectance Model how objects reflect light. Model light sources Algorithms for computing Shading: computing intensities within polygons Determine what light strikes what

  5. VIRTUAL LIGHT: DIGITALLY-GENERATED LIGHTING FOR VIDEO CONFERENCING APPLICATIONS

    E-Print Network [OSTI]

    Fisher, Kathleen

    VIRTUAL LIGHT: DIGITALLY-GENERATED LIGHTING FOR VIDEO CONFERENCING APPLICATIONS Andrea Basso method to improve the lighting conditions of a real scene or video sequence. In particular we concentrate on modifying real light sources intensities and inserting virtual lights into a real scene viewed from a fixed

  6. Thermal treatment wall

    DOE Patents [OSTI]

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

    2000-01-01T23:59:59.000Z

    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.

  7. Tunable thermal link

    DOE Patents [OSTI]

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

    2014-07-15T23:59:59.000Z

    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.

  8. Solar thermal aircraft

    DOE Patents [OSTI]

    Bennett, Charles L. (Livermore, CA)

    2007-09-18T23:59:59.000Z

    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.

  9. Optical device with low electrical and thermal resistance bragg reflectors

    DOE Patents [OSTI]

    Lear, Kevin L. (Albuquerque, NM)

    1996-01-01T23:59:59.000Z

    A compound-semiconductor optical device and method. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors.

  10. Optical device with low electrical and thermal resistance Bragg reflectors

    DOE Patents [OSTI]

    Lear, K.L.

    1996-10-22T23:59:59.000Z

    A compound-semiconductor optical device and method are disclosed. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors. 16 figs.

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

    SciTech Connect (OSTI)

    Guidotti, Ronald Armand

    2006-06-01T23:59:59.000Z

    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.

  12. Detecting coherent phonon wave effects in superlattices using time-domain thermoreflectance

    E-Print Network [OSTI]

    Luckyanova, Maria N. (Maria Nickolayevna)

    2012-01-01T23:59:59.000Z

    Superlattices (SLs), structures consisting of periodic layers of thin films of several angstroms to tens of nanometers thick, have unique electrical and thermal properties that make them well suited for applications in ...

  13. PHYSICAL REVIEW B 88, 035428 (2013) Phonons in twisted bilayer graphene

    E-Print Network [OSTI]

    2013-01-01T23:59:59.000Z

    solar cells,9 resonators,10 and thermal management of ultralarge scale integrated circuits and high-power rotation angles. The calculations are performed using the Born­von Karman model for the intralayer atomic

  14. Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01T23:59:59.000Z

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  15. High-Temperature Thermal Array for Next Generation Solar Thermal...

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

    Thermal Array for Next Generation Solar Thermal Power Production Award Number: DE-EE00025828 Report Date: March 15, 2013 PI: Stephen Obrey * Technical approach is focused on...

  16. Lakeview Light and Power- Commercial Lighting Rebate Program

    Broader source: Energy.gov [DOE]

    Lakeview Light and Power offers a commercial lighting rebate program. Rebates apply to the installation of energy efficient lighting retrofits in non-residential buildings. The rebate program is...

  17. Green Light Pulse Oximeter

    DOE Patents [OSTI]

    Scharf, John Edward (Oldsmar, FL)

    1998-11-03T23:59:59.000Z

    A reflectance pulse oximeter that determines oxygen saturation of hemoglobin using two sources of electromagnetic radiation in the green optical region, which provides the maximum reflectance pulsation spectrum. The use of green light allows placement of an oximetry probe at central body sites (e.g., wrist, thigh, abdomen, forehead, scalp, and back). Preferably, the two green light sources alternately emit light at 560 nm and 577 nm, respectively, which gives the biggest difference in hemoglobin extinction coefficients between deoxyhemoglobin, RHb, and oxyhemoglobin, HbO.sub.2.

  18. White light velocity interferometer

    DOE Patents [OSTI]

    Erskine, D.J.

    1999-06-08T23:59:59.000Z

    The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

  19. Effect of wettability on light oil steamflooding

    SciTech Connect (OSTI)

    Olsen, D.K.

    1991-12-01T23:59:59.000Z

    This report summarizes NIPER`s research on four interrelated topics for Light Oil Steamflooding. Four interrelated topics are described: The methodology for measuring capillary pressure and wettability at elevated temperature, the use of silylating agents to convert water-wet Berea sandstones or unconsolidated quartz sands to oil-wetted surfaces, the evaluation of the thermal hydrolytic stability of these oil-wet surfaces for possible use in laboratory studies using steam and hot water to recover oil, and the effect of porous media of different wettabilities on oil recovery where the porous media is first waterflooded and then steamflooded.

  20. Effect of wettability on light oil steamflooding

    SciTech Connect (OSTI)

    Olsen, D.K.

    1991-12-01T23:59:59.000Z

    This report summarizes NIPER's research on four interrelated topics for Light Oil Steamflooding. Four interrelated topics are described: The methodology for measuring capillary pressure and wettability at elevated temperature, the use of silylating agents to convert water-wet Berea sandstones or unconsolidated quartz sands to oil-wetted surfaces, the evaluation of the thermal hydrolytic stability of these oil-wet surfaces for possible use in laboratory studies using steam and hot water to recover oil, and the effect of porous media of different wettabilities on oil recovery where the porous media is first waterflooded and then steamflooded.

  1. Light Duty Efficient, Clean Combustion

    SciTech Connect (OSTI)

    Donald Stanton

    2010-12-31T23:59:59.000Z

    Cummins has successfully completed the Light Duty Efficient Clean Combustion (LDECC) cooperative program with DoE. This program was established in 2007 in support of the Department of Energy's Vehicles Technologies Advanced Combustion and Emissions Control initiative to remove critical barriers to the commercialization of advanced, high efficiency, emissions compliant internal combustion (IC) engines for light duty vehicles. Work in this area expanded the fundamental knowledge of engine combustion to new regimes and advanced the knowledge of fuel requirements for these diesel engines to realize their full potential. All of the following objectives were met with fuel efficiency improvement targets exceeded: (1) Improve light duty vehicle (5000 lb. test weight) fuel efficiency by 10.5% over today's state-of-the-art diesel engine on the FTP city drive cycle; (2) Develop and design an advanced combustion system plus aftertreatment system that synergistically meets Tier 2 Bin 5 NOx and PM emissions standards while demonstrating the efficiency improvements; (3) Maintain power density comparable to that of current conventional engines for the applicable vehicle class; and (4) Evaluate different fuel components and ensure combustion system compatibility with commercially available biofuels. Key accomplishments include: (1) A 25% improvement in fuel efficiency was achieved with the advanced LDECC engine equipped with a novel SCR aftertreatment system compared to the 10.5% target; (2) An 11% improvement in fuel efficiency was achieved with the advanced LDECC engine and no NOx aftertreamtent system; (3) Tier 2 Bin 5 and SFTP II emissions regulations were met with the advanced LDECC engine equipped with a novel SCR aftertreatment system; (4) Tier 2 Bin 5 emissions regulations were met with the advanced LDECC engine and no NOx aftertreatment, but SFTP II emissions regulations were not met for the US06 test cycle - Additional technical barriers exist for the no NOx aftertreatment engine; (5) Emissions and efficiency targets were reached with the use of biodiesel. A variety of biofuel feedstocks (soy, rapeseed, etc.) was investigated; (6) The advanced LDECC engine with low temperature combustion was compatible with commercially available biofuels as evaluated by engine performance testing and not durability testing; (7) The advanced LDECC engine equipped with a novel SCR aftertreatment system is the engine system architecture that is being further developed by the Cummins product development organization. Cost reduction and system robustness activities have been identified for future deployment; (8) The new engine and aftertreatment component technologies are being developed by the Cummins Component Business units (e.g. fuel system, turbomachinery, aftertreatment, electronics, etc.) to ensure commercial viability and deployment; (9) Cummins has demonstrated that the technologies developed for this program are scalable across the complete light duty engine product offerings (2.8L to 6.7L engines); and (10) Key subsystems developed include - sequential two stage turbo, combustions system for low temperature combustion, novel SCR aftertreatment system with feedback control, and high pressure common rail fuel system. An important element of the success of this project was leveraging Cummins engine component technologies. Innovation in component technology coupled with system integration is enabling Cummins to move forward with the development of high efficiency clean diesel products with a long term goal of reaching a 40% improvement in thermal efficiency for the engine plus aftertreatment system. The 40% improvement is in-line with the current light duty vehicle efficiency targets set by the 2010 DoE Vehicle Technologies MYPP and supported through co-operative projects such as the Cummins Advanced Technology Powertrains for Light-Duty Vehicles (ATP-LD) started in 2010.

  2. Light Duty Efficient, Clean Combustion

    SciTech Connect (OSTI)

    Stanton, Donald W

    2011-06-03T23:59:59.000Z

    Cummins has successfully completed the Light Duty Efficient Clean Combustion (LDECC) cooperative program with DoE. This program was established in 2007 in support of the Department of Energy’s Vehicles Technologies Advanced Combustion and Emissions Control initiative to remove critical barriers to the commercialization of advanced, high efficiency, emissions compliant internal combustion (IC) engines for light duty vehicles. Work in this area expanded the fundamental knowledge of engine combustion to new regimes and advanced the knowledge of fuel requirements for these diesel engines to realize their full potential. All of the following objectives were met with fuel efficiency improvement targets exceeded: 1. Improve light duty vehicle (5000 lb. test weight) fuel efficiency by 10.5% over today’s state-ofthe- art diesel engine on the FTP city drive cycle 2. Develop & design an advanced combustion system plus aftertreatment system that synergistically meets Tier 2 Bin 5 NOx and PM emissions standards while demonstrating the efficiency improvements. 3. Maintain power density comparable to that of current conventional engines for the applicable vehicle class. 4. Evaluate different fuel components and ensure combustion system compatibility with commercially available biofuels. Key accomplishments include: ? A 25% improvement in fuel efficiency was achieved with the advanced LDECC engine equipped with a novel SCR aftertreatment system compared to the 10.5% target ? An 11% improvement in fuel efficiency was achieved with the advanced LDECC engine and no NOx aftertreamtent system ? Tier 2 Bin 5 and SFTP II emissions regulations were met with the advanced LDECC engine equipped with a novel SCR aftertreatment system ? Tier 2 Bin 5 emissions regulations were met with the advanced LDECC engine and no NOx aftertreatment, but SFTP II emissions regulations were not met for the US06 test cycle – Additional technical barriers exist for the no NOx aftertreatment engine ? Emissions and efficiency targets were reached with the use of biodiesel. A variety of biofuel feedstocks (soy, rapeseed, etc.) was investigated. ? The advanced LDECC engine with low temperature combustion was compatible with commercially available biofuels as evaluated by engine performance testing and not durability testing. ? The advanced LDECC engine equipped with a novel SCR aftertreatment system is the engine system architecture that is being further developed by the Cummins product development organization. Cost reduction and system robustness activities have been identified for future deployment. ? The new engine and aftertreatment component technologies are being developed by the Cummins Component Business units (e.g. fuel system, turbomachinery, aftertreatment, electronics, etc.) to ensure commercial viability and deployment ? Cummins has demonstrated that the technologies developed for this program are scalable across the complete light duty engine product offerings (2.8L to 6.7L engines) ? Key subsystems developed include – sequential two stage turbo, combustions system for low temperature combustion, novel SCR aftertreatment system with feedback control, and high pressure common rail fuel system An important element of the success of this project was leveraging Cummins engine component technologies. Innovation in component technology coupled with system integration is enabling Cummins to move forward with the development of high efficiency clean diesel products with a long term goal of reaching a 40% improvement in thermal efficiency for the engine plus aftertreatment system. The 40% improvement is in-line with the current light duty vehicle efficiency targets set by the 2010 DoE Vehicle Technologies MYPP and supported through co-operative projects such as the Cummins Advanced Technology Powertrains for Light- Duty Vehicles (ATP-LD) started in 2010.

  3. 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)

    2000-01-01T23:59:59.000Z

    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.

  4. Thermal excitation of plasmons for near-field thermophotovoltaics

    SciTech Connect (OSTI)

    Guo, Yu; Molesky, Sean; Hu, Huan; Cortes, Cristian L.; Jacob, Zubin, E-mail: zjacob@ualberta.ca [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)

    2014-08-18T23:59:59.000Z

    The traditional approaches of exciting plasmons consist of either using electrons (e.g., electron energy loss spectroscopy) or light (Kretchman and Otto geometry) while more recently plasmons have been excited even by single photons. A different approach: thermal excitation of a plasmon resonance at high temperatures using alternate plasmonic media was proposed by S. Molesky et al. [Opt. Express 21, A96–A110 (2013)]. Here, we show how the long-standing search for a high temperature narrowband near-field emitter for thermophotovoltaics can be fulfilled by thermally exciting plasmons. We also describe a method to control Wein's displacement law in the near-field using high temperature epsilon-near-zero metamaterials. Finally, we show that our work opens up an interesting direction of research for the field of slow light: thermal emission control.

  5. Solar Thermal Conversion

    SciTech Connect (OSTI)

    Kreith, F.; Meyer, R. T.

    1982-11-01T23:59:59.000Z

    The thermal conversion process of solar energy is based on well-known phenomena of heat transfer (Kreith 1976). In all thermal conversion processes, solar radiation is absorbed at the surface of a receiver, which contains or is in contact with flow passages through which a working fluid passes. As the receiver heats up, heat is transferred to the working fluid which may be air, water, oil, or a molten salt. The upper temperature that can be achieved in solar thermal conversion depends on the insolation, the degree to which the sunlight is concentrated, and the measures taken to reduce heat losses from the working fluid.

  6. Sandia Energy - (Lighting and) Solid-State Lighting: Science...

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

    on the third and upcoming revolution (illumination). Topics cover the basics of light-emitting diode (LED) operation; a 200-year history of lighting technology; the importance of...

  7. Sandia National Laboratories: (Lighting and) Solid-State Lighting...

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

    on the third and upcoming revolution (illumination). Topics cover the basics of light-emitting diode (LED) operation; a 200-year history of lighting technology; the importance of...

  8. Columbia Water and Light- HVAC and Lighting Efficiency Rebates

    Broader source: Energy.gov [DOE]

    Columbia Water and Light (CWL) offers rebates to its commercial and industrial customers for the purchase of high efficiency HVAC installations and efficient lighting. Incentives for certain...

  9. Reading Municipal Light Department- Business Lighting Rebate Program

    Broader source: Energy.gov [DOE]

    Reading Municipal Light Department (RMLD) offers incentives for non-residential customers to install energy efficient lights and sensors in existing facilities. In addition to rebates for the...

  10. Peninsula Light Company- Commercial Efficient Lighting Rebate Program

    Broader source: Energy.gov [DOE]

    Peninsula Light Company (PLC) offers a rebate program for commercial customers who wish to upgrade to energy efficient lighting. Participating customers must be served by PLC commercial service....

  11. Light Duty Combustion Research: Advanced Light-Duty Combustion...

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

    duty Diesel Combustion Research Advanced Light-Duty Combustion Experiments Paul Miles Sandia National Laboratories Light-Duty Combustion Modeling Rolf Reitz University of Wisconsin...

  12. Thermal insulations using vacuum panels

    DOE Patents [OSTI]

    Glicksman, Leon R. (Lynnfield, MA); Burke, Melissa S. (Pittsburgh, PA)

    1991-07-16T23:59:59.000Z

    Thermal insulation vacuum panels are formed of an inner core of compressed low thermal conductivity powders enclosed by a ceramic/glass envelope evaluated to a low pressure.

  13. Efficient Light Sources Today

    E-Print Network [OSTI]

    Hart, A. L.

    1982-01-01T23:59:59.000Z

    This paper reviews new lamp and lighting technology in terms of application and economic impact. Included are the latest advances in High Intensity Discharge systems, energy saving fluorescent lamps and ballasts, and the new state of the art high...

  14. Natural lighting and skylights

    E-Print Network [OSTI]

    Evans, Benjamin Hampton

    1961-01-01T23:59:59.000Z

    outlined herein, the feasibility of using scale models for studying skylights is also an established fact. The method of analysis by models can be a valuable tool to any designer who is concerned about day-lighting....

  15. National Synchrotron Light Source

    ScienceCinema (OSTI)

    None

    2010-01-08T23:59:59.000Z

    A tour of Brookhaven's National Synchrotron Light Source (NSLS). The NSLS is one of the world's most widely used scientific research facilities, hosting more than 2,500 guest researchers each year. The NSLS provides intense beams of infrared, ultraviole

  16. Light Vector Mesons

    E-Print Network [OSTI]

    Alexander Milov

    2008-12-21T23:59:59.000Z

    This article reviews the current status of experimental results obtained in the measurement of light vector mesons produced in proton-proton and heavy ion collisions at different energies. The review is focused on two phenomena related to the light vector mesons; the modification of the spectral shape in search of Chiral symmetry restoration and suppression of the meson production in heavy ion collisions. The experimental results show that the spectral shape of light vector mesons are modified compared to the parameters measured in vacuum. The nature and the magnitude of the modification depends on the energy density of the media in which they are produced. The suppression patterns of light vector mesons are different from the measurements of other mesons and baryons. The mechanisms responsible for the suppression of the mesons are not yet understood. Systematic comparison of existing experimental results points to the missing data which may help to resolve the problem.

  17. Light and Plants Plants use light to photosynthesize. Name two places that light can come from

    E-Print Network [OSTI]

    Koptur, Suzanne

    Light and Plants Plants use light to photosynthesize. Name two places that light can come from: 1 (CO2, a gas) from the air and turn it into SUGARS (food). This process is powered by energy from light plants) for energy. Photosynthetically Active Radiation (PAR) is a combination of red light and blue

  18. Characterization and modeling of thermal diffusion and aggregation in nanofluids.

    SciTech Connect (OSTI)

    Gharagozloo, Patricia E.; Goodson, Kenneth E. (Stanford University, Stanford, CA)

    2010-05-01T23:59:59.000Z

    Fluids with higher thermal conductivities are sought for fluidic cooling systems in applications including microprocessors and high-power lasers. By adding high thermal conductivity nanoscale metal and metal oxide particles to a fluid the thermal conductivity of the fluid is enhanced. While particle aggregates play a central role in recent models for the thermal conductivity of nanofluids, the effect of particle diffusion in a temperature field on the aggregation and transport has yet to be studied in depth. The present work separates the effects of particle aggregation and diffusion using parallel plate experiments, infrared microscopy, light scattering, Monte Carlo simulations, and rate equations for particle and heat transport in a well dispersed nanofluid. Experimental data show non-uniform temporal increases in thermal conductivity above effective medium theory and can be well described through simulation of the combination of particle aggregation and diffusion. The simulation shows large concentration distributions due to thermal diffusion causing variations in aggregation, thermal conductivity and viscosity. Static light scattering shows aggregates form more quickly at higher concentrations and temperatures, which explains the increased enhancement with temperature reported by other research groups. The permanent aggregates in the nanofluid are found to have a fractal dimension of 2.4 and the aggregate formations that grow over time are found to have a fractal dimension of 1.8, which is consistent with diffusion limited aggregation. Calculations show as aggregates grow the viscosity increases at a faster rate than thermal conductivity making the highly aggregated nanofluids unfavorable, especially at the low fractal dimension of 1.8. An optimum nanoparticle diameter for these particular fluid properties is calculated to be 130 nm to optimize the fluid stability by reducing settling, thermal diffusion and aggregation.

  19. Light and Energy -Daylight measurements

    E-Print Network [OSTI]

    Light and Energy - Daylight measurements #12;Light and Energy - Daylight measurements Authors: Jens;3 Title Light and Energy Subtitle Daylight measurements Authors Jens Christoffersen, Ásta Logadóttir ........................................................................................................ 5 Daylight quantity

  20. Light as a Healing Mechanism

    E-Print Network [OSTI]

    Lingampalli, Nithya

    2013-01-01T23:59:59.000Z

    S. (1991). Meridians conduct light. Moskow: Raum and Zeit.the bod’ys absorption of light. Explore, 9(2), doi: https://01). The healing use of light and color. Health Care Design

  1. Method and apparatus for thermal management of vehicle exhaust systems

    DOE Patents [OSTI]

    Benson, D.K.; Potter, T.F.

    1995-12-26T23:59:59.000Z

    A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter. 7 figs.

  2. July 18, 2012 Using QECBs for Street Lighting Upgrades

    E-Print Network [OSTI]

    lighting technologies (e.g. light-emitting diodes, induction lighting) can reduce street light energy

  3. Thermal dilepton rates from quenched lattice QCD

    E-Print Network [OSTI]

    H. -T. Ding; A. Francis; O. Kaczmarek; F. Karsch; E. Laermann; S. Mukherjee; M. Müller; W. Soeldner

    2013-01-30T23:59:59.000Z

    We present new lattice results on the continuum extrapolation of the vector current correlation function. Lattice calculations have been carried out in the deconfined phase at a temperature of 1.1 Tc, extending our previous results at 1.45 Tc, utilizing quenched non-perturbatively clover-improved Wilson fermions and light quark masses. A systematic analysis on multiple lattice spacings allows to perform the continuum limit of the correlation function and to extract spectral properties in the continuum limit. Our current analysis suggests the results for the electrical conductivity are proportional to the temperature and the thermal dilepton rates in the quark gluon plasma are comparable for both temperatures. Preliminary results of the continuum extrapolated correlation function at finite momenta, which relates to thermal photon rates, are also presented.

  4. Collective Thermotaxis of Thermally Active Colloids

    E-Print Network [OSTI]

    Ramin Golestanian

    2011-10-07T23:59:59.000Z

    Colloids with patchy metal coating under laser irradiation could act as local sources of heat due to the absorption of light. While for asymmetric colloids this could induce self-propulsion, it also leads to the generation of a slowly decaying temperature profile that other colloids could interact with. The collective behavior of a dilute solution of such thermally active particles is studied using a stochastic formulation. It is found that when the Soret coefficient is positive, the system could be described in stationary-state by the nonlinear Poisson-Boltzmann equation and could adopt density profiles with significant depletion in the middle region when confined. For colloids with negative Soret coefficient, the system can be described as a dissipative equivalent of a gravitational system. It is shown that in this case the thermally active colloidal solution could undergo an instability at a critical laser intensity, which has similarities to supernova explosion.

  5. Thermal Insulation Systems

    E-Print Network [OSTI]

    Stanley, T. F.

    1982-01-01T23:59:59.000Z

    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...

  6. Thermally driven circulation

    E-Print Network [OSTI]

    Nelken, Haim

    1987-01-01T23:59:59.000Z

    Several problems connected by the theme of thermal forcing are addressed herein. The main topic is the stratification and flow field resulting from imposing a specified heat flux on a fluid that is otherwise confined to a ...

  7. Photovoltaic-thermal collectors

    DOE Patents [OSTI]

    Cox, III, Charles H. (Carlisle, MA)

    1984-04-24T23:59:59.000Z

    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.

  8. Phonon-roton modes of liquid 4He beyond the roton in MCM-41

    SciTech Connect (OSTI)

    Azuah, Richard T [NIST Center for Neutron Research (NCRN), Gaithersburg, MD] NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Omar Diallo, Souleymane [ORNL] ORNL; Adams, Mark A. [ISIS Facility, Rutherford Appleton Laboratory (ISIS)] ISIS Facility, Rutherford Appleton Laboratory (ISIS); Kirichek, Oleg [ISIS Facility, Rutherford Appleton Laboratory (ISIS)] ISIS Facility, Rutherford Appleton Laboratory (ISIS); Glyde, Henry R [University of Delaware] University of Delaware

    2013-01-01T23:59:59.000Z

    We present neutron scattering measurements of the phonon-roton (P-R) mode of superfluid 4He confined in 47 A MCM-41 at T = 0.5 K at wave vectors, Q, beyond the roton wave vector (QR = 1.92 A-1). Measurements beyond the roton require access to high wave vectors (up to Q = 4 A-1) with excellent energy resolution and high statistical precision. The present results show for the first time that at T = 0.5 K the P-R mode in MCM-41 extends out to wave-vector Q 3.6 A-1 with the same energy and zero width (within precision) as observed in bulk superfluid 4He. Layer modes in the roton region are also observed. Specifically, the P-R mode energy, !Q, increases with Q for Q > QR and reaches a plateau at a maximum energy !Q = 2 where is the roton energy, = 0.74 0.01 meV in MCM-41. This upper limit means the P-R mode decays to two rotons when its energy exceeds 2 . It also means that the P-R mode does not decay to two layers modes. If the P-R could decay to two layer modes, !Q would plateau at a lower energy, !Q = 2 L where L = 0.60 meV is the energy of the roton like minimum of the layer mode. The observation of the P-R mode with energy up to 2 shows that the P-R mode and the layer modes are independent modes with apparently little interaction between them.

  9. Sandia National Laboratories: White Light Creation Architectures

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

    Light Creation Architectures White Light Creation Architectures Overview of SSL White Light Creation Architectures The entire spectral range of visible light can be...

  10. Sandia National Laboratories: Lighting Developments to 2030

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

    ClimateLighting Developments to 2030 Lighting Developments to 2030 videobanner Lighting Technologies, Costs, and Energy Demand: Global Developments to 2030 V iew Slides: Lighting...

  11. Interior Light Level Measurements Appendix F -Interior Light Level Measurements

    E-Print Network [OSTI]

    Appendix F ­ Interior Light Level Measurements #12;F.1 Appendix F - Interior Light Level. A potential concern is that a lower VT glazing may increase electric lighting use to compensate for lost qualify and quantify a representative loss of daylighting, and therefore electric lighting use

  12. Quasi light fields: extending the light field to coherent radiation

    E-Print Network [OSTI]

    Wornell, Gregory W.

    Quasi light fields: extending the light field to coherent radiation Anthony Accardi1,2 and Gregory light field, and for coherent radiation using electromagnetic field theory. We present a model of coherent image formation that strikes a balance between the utility of the light field

  13. Lighting affects appearance LightSource emits photons

    E-Print Network [OSTI]

    Jacobs, David

    1 Lighting affects appearance #12;2 LightSource emits photons Photons travel in a straight line). And then some reach the eye/camera. #12;3 Basic fact: Light is linear Double intensity of sources, double photons reaching eye. Turn on two lights, and photons reaching eye are same as sum of number when each

  14. Smart Lighting: A Second Wave in Solid State Lighting?

    E-Print Network [OSTI]

    Salama, Khaled

    Smart Lighting: A Second Wave in Solid State Lighting? OIDA Conference on Green Photonics Bob Karlicek Director, Smart Lighting Engineering Research Center Rensselaer Polytechnic Institute June 2010 #12;2 Outline · The First Wave of Solid State Lighting · Complex Dynamics in the Supply Chain · What

  15. Electromagnetically Induced Transparency and Slow Light with Optomechanics

    E-Print Network [OSTI]

    Amir H. Safavi-Naeini; Thiago P. Mayer Alegre; Jasper Chan; Matt Eichenfield; Martin Winger; Qiang Lin; Jeffrey T. Hill; Darrick Chang; Oskar Painter

    2010-12-14T23:59:59.000Z

    Controlling the interaction between localized optical and mechanical excitations has recently become possible following advances in micro- and nano-fabrication techniques. To date, most experimental studies of optomechanics have focused on measurement and control of the mechanical subsystem through its interaction with optics, and have led to the experimental demonstration of dynamical back-action cooling and optical rigidity of the mechanical system. Conversely, the optical response of these systems is also modified in the presence of mechanical interactions, leading to strong nonlinear effects such as Electromagnetically Induced Transparency (EIT) and parametric normal-mode splitting. In atomic systems, seminal experiments and proposals to slow and stop the propagation of light, and their applicability to modern optical networks, and future quantum networks, have thrust EIT to the forefront of experimental study during the last two decades. In a similar fashion, here we use the optomechanical nonlinearity to control the velocity of light via engineered photon-phonon interactions. Our results demonstrate EIT and tunable optical delays in a nanoscale optomechanical crystal device, fabricated by simply etching holes into a thin film of silicon (Si). At low temperature (8.7 K), we show an optically-tunable delay of 50 ns with near-unity optical transparency, and superluminal light with a 1.4 microseconds signal advance. These results, while indicating significant progress towards an integrated quantum optomechanical memory, are also relevant to classical signal processing applications. Measurements at room temperature and in the analogous regime of Electromagnetically Induced Absorption (EIA) show the utility of these chip-scale optomechanical systems for optical buffering, amplification, and filtering of microwave-over-optical signals.

  16. Defect correlated fluorescent quenching and electron phonon coupling in the spectral transition of Eu{sup 3+} in CaTiO{sub 3} for red emission in display application

    SciTech Connect (OSTI)

    Som, S., E-mail: sudipta.som@gmail.com, E-mail: swarthc@ufs.ac.za; Kumar, Vinod; Kumar, Vijay; Terblans, J. J.; Swart, H. C., E-mail: sudipta.som@gmail.com, E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Box 339, Bloemfontein 9300 (South Africa); Kunti, A. K.; Dutta, S.; Chowdhury, M.; Sharma, S. K. [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India)

    2014-05-21T23:59:59.000Z

    This paper reports on the defect correlated self-quenching and spectroscopic investigation of calcium titanate (CaTiO{sub 3}) phosphors. A series of CaTiO{sub 3} phosphors doped with trivalent europium (Eu{sup 3+}) and codoped with potassium (K{sup +}) ions were prepared by the solid state reaction method. The X-ray diffraction results revealed that the obtained powder phosphors consisted out of a single-phase orthorhombic structure and it also indicated that the incorporation of the dopants/co-dopants did not affect the crystal structure. The scanning electron microscopy images revealed the irregular morphology of the prepared phosphors consisting out of ?m sized diameter particles. The Eu{sup 3+} doped phosphors illuminated with ultraviolet light showed the characteristic red luminescence corresponding to the {sup 5}D{sub 0}?{sup 7}F{sub J} transitions of Eu{sup 3+}. As a charge compensator, K{sup +} ions were incorporated into the CaTiO{sub 3}:Eu{sup 3+} phosphors, which enhanced the photoluminescence (PL) intensities depending on the doping concentration of K{sup +}. The concentration quenching of Eu{sup 3+} in this host is discussed in the light of ion-ion interaction, electron phonon coupling, and defect to ion energy transfer. The spectral characteristics and the Eu-O ligand behaviour were determined using the Judd-Ofelt theory from the PL spectra instead of the absorption spectra. The CIE (International Commission on Illumination) parameters were calculated using spectral energy distribution functions and McCamy's empirical formula. Photometric characterization indicated the suitability of K{sup +} compensated the CaTiO{sub 3}:Eu{sup 3+} phosphor for pure red emission in light-emitting diode applications.

  17. Enhancement of surface phonon modes in the Raman spectrum of ZnSe nanoparticles on adsorption of 4-mercaptopyridine

    SciTech Connect (OSTI)

    Islam, Syed K.; Lombardi, John R. [Department of Chemistry, The City College of New York, New York, New York 10031 (United States)] [Department of Chemistry, The City College of New York, New York, New York 10031 (United States)

    2014-02-21T23:59:59.000Z

    By chemically etching a thin film of crystalline ZnSe with acid, we observe a strong Raman enhancement of the surface phonon modes of ZnSe on adsorption of a molecule (4-mercaptopyridine). The surface is composed of oblate hemi-ellipsoids, which has a large surface-to-bulk ratio. The assignment of the observed modes (at 248 and 492 cm{sup ?1}) to a fundamental and first overtone of the surface optical mode is consistent with observations from high-resolution electron energy loss spectroscopy as well as calculations.

  18. Influence of Controlled Viscous Dissipation on the Propagation of Strongly Nonlinear Waves in Stainless Steel Based Phononic Crystals

    E-Print Network [OSTI]

    E. B. Herbold; V. F. Nesterenko; C. Daraio

    2005-12-22T23:59:59.000Z

    Strongly nonlinear phononic crystals were assembled from stainless steel spheres. Single solitary waves and splitting of an initial pulse into a train of solitary waves were investigated in different viscous media using motor oil and non-aqueous glycerol to introduce a controlled viscous dissipation. Experimental results indicate that the presence of a viscous fluid dramatically altered the splitting of the initial pulse into a train of solitary waves. Numerical simulations qualitatively describe the observed phenomena only when a dissipative term based on the relative velocity between particles is introduced.

  19. Flip-chip light emitting diode with resonant optical microcavity

    SciTech Connect (OSTI)

    Gee, James M.; Bogart, Katherine H.A.; Fischer, Arthur J.

    2005-11-29T23:59:59.000Z

    A flip-chip light emitting diode with enhanced efficiency. The device structure employs a microcavity structure in a flip-chip configuration. The microcavity enhances the light emission in vertical modes, which are readily extracted from the device. Most of the rest of the light is emitted into waveguided lateral modes. Flip-chip configuration is advantageous for light emitting diodes (LEDs) grown on dielectric substrates (e.g., gallium nitride LEDs grown on sapphire substrates) in general due to better thermal dissipation and lower series resistance. Flip-chip configuration is advantageous for microcavity LEDs in particular because (a) one of the reflectors is a high-reflectivity metal ohmic contact that is already part of the flip-chip configuration, and (b) current conduction is only required through a single distributed Bragg reflector. Some of the waveguided lateral modes can also be extracted with angled sidewalls used for the interdigitated contacts in the flip-chip configuration.

  20. Oxycarbonitride phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

    2014-07-08T23:59:59.000Z

    Disclosed herein is a novel family of oxycarbonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

  1. Oxycarbonitride phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

    2013-10-08T23:59:59.000Z

    Disclosed herein is a novel family of oxycarbidonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbidonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

  2. High-energy phonon confinement in nanoscale metallic multilayers B. Roldan Cuenya,1,* W. Keune,1,2 R. Peters,2 E. Schuster,2 B. Sahoo,2 U. von Hrsten,2 W. Sturhahn,3 J. Zhao,3

    E-Print Network [OSTI]

    Kik, Pieter

    in metallic multilayer structures.11­13 The classical method of inelastic neutron scattering remains by nuclear resonant inelastic x-ray scattering. With decreasing Fe thickness, the high-energy phonon peak optical phonons in metallic Co/Ru multilayers.10 However, Raman scattering is sensi- tive to long

  3. Sneaky light stop

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

    Eifert, Till; Nachman, Benjamin

    2015-04-01T23:59:59.000Z

    A light supersymmetric top quark partner (stop) with a mass nearly degenerate with that of the standard model (SM) top quark can evade direct searches. The precise measurement of SM top properties such as the cross-section has been suggested to give a handle for this ‘stealth stop’ scenario. We present an estimate of the potential impact a light stop may have on top quark mass measurements. The results indicate that certain light stop models may induce a bias of up to a few GeV, and that this effect can hide the shift in, and hence sensitivity from, cross-section measurements. Duemore »to the different initial states, the size of the bias is slightly different between the LHC and the Tevatron. The studies make some simplifying assumptions for the top quark measurement technique, and are based on truth-level samples.« less

  4. Pupillary efficient lighting system

    DOE Patents [OSTI]

    Berman, Samuel M. (San Francisco, CA); Jewett, Don L. (Mill Valley, CA)

    1991-01-01T23:59:59.000Z

    A lighting system having at least two independent lighting subsystems each with a different ratio of scotopic illumination to photopic illumination. The radiant energy in the visible region of the spectrum of the lighting subsystems can be adjusted relative to each other so that the total scotopic illumination of the combined system and the total photopic illumination of the combined system can be varied independently. The dilation or contraction of the pupil of an eye is controlled by the level of scotopic illumination and because the scotopic and photopic illumination can be separately controlled, the system allows the pupil size to be varied independently of the level of photopic illumination. Hence, the vision process can be improved for a given level of photopic illumination.

  5. Light emitting ceramic device

    DOE Patents [OSTI]

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18T23:59:59.000Z

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  6. Light harvesting arrays

    DOE Patents [OSTI]

    Lindsey, Jonathan S. (Raleigh, NC)

    2002-01-01T23:59:59.000Z

    A light harvesting array useful for the manufacture of devices such as solar cells comprises: (a) a first substrate comprising a first electrode; and (b) a layer of light harvesting rods electrically coupled to the first electrode, each of the light harvesting rods comprising a polymer of Formula I: X.sup.1.paren open-st.X.sup.m+1).sub.m (I) wherein m is at least 1, and may be from two, three or four to 20 or more; X.sup.1 is a charge separation group (and preferably a porphyrinic macrocycle, which may be one ligand of a double-decker sandwich compound) having an excited-state of energy equal to or lower than that of X.sup.2, and X.sup.2 through X.sup.m+1 are chromophores (and again are preferably porphyrinic macrocycles).

  7. Article for thermal energy storage

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    2000-06-27T23:59:59.000Z

    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.

  8. Holographic thermalization in noncommutative geometry

    E-Print Network [OSTI]

    Xiao-Xiong Zeng; Xian-Ming Liu; Wen-Biao Liu

    2015-05-02T23:59:59.000Z

    Gravitational collapse of a shell of dust in noncommutative geometry is probed by the renormalized geodesic length, which is dual to probe the thermalization by the two-point correlation function in the dual conformal field theory. We find that larger the noncommutative parameter is, longer the thermalization time is, which implies that the large noncommutative parameter delays the thermalization process. We also investigate how the noncommutative parameter affects the thermalization velocity and thermalization acceleration.

  9. MANDATORY MEASURES INDOOR LIGHTING CONTROLS

    E-Print Network [OSTI]

    California at Davis, University of

    MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 4 MANDATORY LIGHTING CONTROLS 1. 130.1 (a) Area Controls: Manual controls that control lighting in each area separately 2. 130.1 (b) Multi-level Controls: Allow occupants to choose the appropriate light level for each

  10. MANDATORY MEASURES INDOOR LIGHTING CONTROLS

    E-Print Network [OSTI]

    California at Davis, University of

    MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 3 MANDATORY LIGHTING CONTROLS 1. 130.1 (a) Area Controls: Manual controls that control lighting in each area separately 2. 130.1 (b) Multi-level Controls: "Dimmability." Allow occupants to choose the appropriate light

  11. MANDATORY MEASURES INDOOR LIGHTING CONTROLS

    E-Print Network [OSTI]

    California at Davis, University of

    MANDATORY MEASURES INDOOR LIGHTING CONTROLS (Reference: Sub-Chapter 4, Section 130.1) #12;SECTION 5 MANDATORY LIGHTING CONTROLS 1. Area Controls: Manual controls that control lighting in each area separately 2. Multi-level Controls: Allow occupants to choose the appropriate light level for each area 3. Shut

  12. LIGHTING 101 1. Common terminology

    E-Print Network [OSTI]

    California at Davis, University of

    SECTION 3 LIGHTING 101 1. Common terminology 2. Sources & luminaires 3. Controls #12;SECTION 3SECTION 3 DISCUSSION: COMMON LIGHTING TERMINOLOGY 1. What are the definitions of the following lighting terms? 2. Do you use these terms in professional practice? 3. What other lighting terminology do you use

  13. LIGHTING 101 1. Common terminology

    E-Print Network [OSTI]

    California at Davis, University of

    LIGHTING 101 1. Common terminology 2. Sources and luminaires 3. Controls #12;SECTION 2 DISCUSSION: COMMON LIGHTING TERMINOLOGY 1. What are the definitions of the following lighting terms? 2. Do you use these terms in professional practice? 3. What other lighting terminology do you use on the job? SLIDE 14

  14. Radioluminescent lighting technology

    SciTech Connect (OSTI)

    Not Available

    1990-01-01T23:59:59.000Z

    The glow-in-the-dark stereotype that characterizes the popular image of nuclear materials is not accidental. When the French scientist, Henri Becquerel, first discovered radioactivity in 1896, he was interested in luminescence. Radioluminescence, the production of light from a mixture of energetic and passive materials, is probably the oldest practical application of the unstable nucleus. Tritium-based radioluminescent lighting, in spite of the biologically favorable character of the gaseous tritium isotope, was included in the general tightening of environmental and safety regulations. Tritium light manufacturers would have to meet two fundamental conditions: (1) The benefit clearly outweighed the risk, to the extent that even the perceived risk of a skeptical public would be overcome. (2) The need was significant enough that the customer/user would be willing and able to afford the cost of regulation that was imposed both in the manufacture, use and eventual disposal of nuclear materials. In 1981, researchers at Oak Ridge National Laboratory were investigating larger radioluminescent applications using byproduct nuclear material such as krypton-85, as well as tritium. By 1982, it appeared that large source, (100 Curies or more) tritium gas tube, lights might be useful for marking runways and drop zones for military operations and perhaps even special civilian aviation applications. The successful development of this idea depended on making the light bright enough and demonstrating that large gas tube sources could be used and maintained safely in the environment. This successful DOE program is now in the process of being completed and closed-out. Working closely with the tritium light industry, State governments and other Federal agencies, the basic program goals have been achieved. This is a detailed report of what they have learned, proven, and discovered. 91 refs., 29 figs., 5 tabs. (JF)

  15. Explaining the observed long coherence effects by 2D photon echo experiments in photosynthetic EET : Two-Component Phonon Spectrum model

    E-Print Network [OSTI]

    Singh, Navinder; Amritkar, R E

    2011-01-01T23:59:59.000Z

    We propose a simple stochastic model which successfully explains the long coherence effects observed in photosynthetic Excitation Energy Transport (EET) by 2D photon echo experiments of G. S. Engel et. al. (Nature, {\\bf 446} 782, (2007)). Our Two-Component Phonon Spectrum (TCPS) model is based upon the division of phonon degrees of freedom into a systematic component which is treated through polaron transformation and a stochastic component which is treated through dynamical disorder. This model successfully explains the observed long coherence upto $ \\sim 600 fsec$ in EET experiments.

  16. Explaining the observed long coherence effects by 2D photon echo experiments in photosynthetic EET : Two-Component Phonon Spectrum model

    E-Print Network [OSTI]

    Navinder Singh; V. M. Kenkre; R. E. Amritkar

    2011-12-16T23:59:59.000Z

    We propose a simple stochastic model which successfully explains the long coherence effects observed in photosynthetic Excitation Energy Transport (EET) by 2D photon echo experiments of G. S. Engel et. al. (Nature, {\\bf 446} 782, (2007)). Our Two-Component Phonon Spectrum (TCPS) model is based upon the division of phonon degrees of freedom into a systematic component which is treated through polaron transformation and a stochastic component which is treated through dynamical disorder. This model successfully explains the observed long coherence upto $ \\sim 600 fsec$ in EET experiments.

  17. Simultaneous sensing of light and sound velocities of fluids in a two-dimensional phoXonic crystal with defects

    SciTech Connect (OSTI)

    Amoudache, Samira [Institut d'Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d'Ascq (France); Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria); Pennec, Yan, E-mail: yan.pennec@univ-lille1.fr; Djafari Rouhani, Bahram [Institut d'Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d'Ascq (France); Khater, Antoine [Institut des Molécules et Matériaux du Mans UMR 6283 CNRS, Université du Maine, 72085 Le Mans (France); Lucklum, Ralf [Institute of Micro and Sensor Systems (IMOS), Otto-von-Guericke-University, Magdeburg (Germany); Tigrine, Rachid [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria)

    2014-04-07T23:59:59.000Z

    We theoretically investigate the potentiality of dual phononic-photonic (the so-called phoxonic) crystals for liquid sensing applications. We study the transmission through a two-dimensional (2D) crystal made of infinite cylindrical holes in a silicon substrate, where one row of holes oriented perpendicular to the propagation direction is filled with a liquid. The infiltrated holes may have a different radius than the regular holes. We show, in the defect structure, the existence of well-defined features (peaks or dips) in the transmission spectra of acoustic and optical waves and estimate their sensitivity to the sound and light velocity of the analyte. Some of the geometrical requirements behave in opposite directions when searching for an efficient sensing of either sound or light velocities. Hence, a compromise in the choice of the parameters may become necessary in making the phoxonic sensor.

  18. Thermal insulated glazing unit

    DOE Patents [OSTI]

    Selkowitz, S.E.; Arasteh, D.K.; Hartmann, J.L.

    1988-04-05T23:59:59.000Z

    An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas. 2 figs.

  19. Thermal insulated glazing unit

    SciTech Connect (OSTI)

    Selkowitz, Stephen E. (Piedmont, CA); Arasteh, Dariush K. (Oakland, CA); Hartmann, John L. (Seattle, WA)

    1991-01-01T23:59:59.000Z

    An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas.

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

    E-Print Network [OSTI]

    Hardin, Corey Lee

    2011-01-01T23:59:59.000Z

    and Background Solar thermal energy collection is anCHANGE THERMAL ENERGY STORAGE FOR CONCENTRATING SOLAR POWERfor Thermal Energy Storage in Concentrated Solar Thermal

  1. Thermal test options

    SciTech Connect (OSTI)

    Koski, J.A.; Keltner, N.R.; Sobolik, K.B.

    1993-02-01T23:59:59.000Z

    Shipping containers for radioactive materials must be qualified to meet a thermal accident environment specified in regulations, such at Title 10, Code of Federal Regulations, Part 71. Aimed primarily at the shipping container design, this report discusses the thermal testing options available for meeting the regulatory requirements, and states the advantages and disadvantages of each approach. The principal options considered are testing with radiant heat, furnaces, and open pool fires. The report also identifies some of the facilities available and current contacts. Finally, the report makes some recommendations on the appropriate use of these different testing methods.

  2. Thermal ignition combustion system

    DOE Patents [OSTI]

    Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

    1988-04-19T23:59:59.000Z

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

  3. Scattering Solar Thermal Concentrators

    Broader source: Energy.gov [DOE]

    "This fact sheet describes a scattering solar thermal concentrators project awarded under the DOE's 2012 SunShot Concentrating Solar Power R&D award program. The team, led by the Pennsylvania State University, is working to demonstrate a new, scattering-based approach to concentrating sunlight that aims to improve the overall performance and reliability of the collector field. The research team aims to show that scattering solar thermal collectors are capable of achieving optical performance equal to state-of-the-art parabolic trough systems, but with the added benefits of immunity to wind-load tracking error, more efficient land use, and utilization of stationary receivers."

  4. Medical catheters thermally manipulated by fiber optic bundles

    DOE Patents [OSTI]

    Chastagner, P.

    1992-10-06T23:59:59.000Z

    A maneuverable medical catheter comprising a flexible tube having a functional tip is described. The catheter is connected to a control source. The functional tip of the catheter carries a plurality of temperature activated elements arranged in parallel and disposed about the functional tip and held in spaced relation at each end. These elements expand when they are heated. A plurality of fiber optic bundles, each bundle having a proximal end attached to the control source and a distal end attached to one of the elements carry light into the elements where the light is absorbed as heat. By varying the optic fiber that is carrying the light and the intensity of the light, the bending of the elements can be controlled and thus the catheter steered. In an alternate embodiment, the catheter carries a medical instrument for gathering a sample of tissue. The instrument may also be deployed and operated by thermal expansion and contraction of its moving parts. 10 figs.

  5. Windows and lighting program

    SciTech Connect (OSTI)

    Not Available

    1990-06-01T23:59:59.000Z

    More than 30% of all energy use in buildings is attributable to two sources: windows and lighting. Together they account for annual consumer energy expenditures of more than $50 billion. Each affects not only energy use by other major building systems, but also comfort and productivity -- factors that influence building economics far more than does direct energy consumption alone. Windows play a unique role in the building envelope, physically separating the conditioned space from the world outside without sacrificing vital visual contact. Throughout the indoor environment, lighting systems facilitate a variety of tasks associated with a wide range of visual requirements while defining the luminous qualities of the indoor environment. Windows and lighting are thus essential components of any comprehensive building science program. Despite important achievements in reducing building energy consumption over the past decade, significant additional savings are still possible. These will come from two complementary strategies: (1) improve building designs so that they effectively apply existing technologies and extend the market penetration of these technologies; and (2) develop advanced technologies that increase the savings potential of each application. Both the Windows and Daylighting Group and the Lighting System Research Group have made substantial contributions in each of these areas, and continue to do so through the ongoing research summarized here. 23 refs., 16 figs.

  6. AIRPORT LIGHTING Session Highlights

    E-Print Network [OSTI]

    Minnesota, University of

    Administration advisory circulars, available online at www.faa.gov or by mail at the following address: Federal Aviation Administration, Airports 800 Independence Ave. S.W. Washington, D.C. 20591 To qualify for federal AND NAVIGATIONAL AIDS A complete list of federal regulations for airfield lighting is located in Federal Aviation

  7. Tokyo Street Lights

    E-Print Network [OSTI]

    Hacker, Randi; Tsutsui, William

    2008-03-12T23:59:59.000Z

    that you have only 17, no 16, no 15 seconds left to get to the other side before the light changes and the impatient American drivers put the pedal to the metal and it's road kill time. Talk about stress! In Tokyo, crossing the street is a leisurely...

  8. Sweetness and light 

    E-Print Network [OSTI]

    Craig, Katie

    2014-07-03T23:59:59.000Z

    1. Sweetness and Light. A novel. Judi lives in a nice, clean house with her seventeen year old stepson, who won’t talk to her in anything but monosyllables. His father, Nelson, and she are struggling to relate to each ...

  9. Systems analysis of thermal storage

    SciTech Connect (OSTI)

    Copeland, R.J.

    1981-08-01T23:59:59.000Z

    During FY 1981, analyses were conducted on thermal storage concepts for solar thermal applications. These studies include estimates of both the obtainable costs of thermal storage concepts and their worth to a user (i.e., value). Based on obtainable costs and performance, an in-depth study evaluated thermal storage concepts for water/steam, organic fluid, and gas/Brayton solar thermal receivers. Promising and nonpromising concepts were identified. A study to evaluate thermal storage concepts for a liquid metal receiver was initiated. The value of thermal storage in a solar thermal industrial process heat application was analyzed. Several advanced concepts are being studied, including ground-mounted thermal storage for parabolic dishes with Stirling engines.

  10. Light induced modulation instability of surfaces under intense illumination

    SciTech Connect (OSTI)

    Burlakov, V. M., E-mail: burlakov@maths.ox.ac.uk; Goriely, A. [Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG (United Kingdom)] [Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG (United Kingdom); Foulds, I. [4700 King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)] [4700 King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)

    2013-12-16T23:59:59.000Z

    We show that a flat surface of a polymer in rubber state illuminated with intense electromagnetic radiation is unstable with respect to periodic modulation. Initial periodic perturbation is amplified due to periodic thermal expansion of the material heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source. Therefore, it is not related to the well-known laser induced periodic structures on polymer surfaces but may contribute to their formation and to other phenomena of light-matter interaction.

  11. Full light absorption in single arrays of spherical nanoparticles

    E-Print Network [OSTI]

    Ra'di, Y; Kosulnikov, S U; Omelyanovich, M M; Morits, D; Osipov, A V; Simovski, C R; Tretyakov, S A

    2015-01-01T23:59:59.000Z

    In this paper we show that arrays of core-shell nanoparticles function as effective thin absorbers of light. In contrast to known metamaterial absorbers, the introduced absorbers are formed by single planar arrays of spherical inclusions and enable full absorption of light incident on either or both sides of the array. We demonstrate possibilities for realizing different kinds of symmetric absorbers, including resonant, ultra-broadband, angularly selective, and all-angle absorbers. The physical principle behind these designs is explained considering balanced electric and magnetic responses of unit cells. Photovoltaic devices and thermal emitters are the two most important potential applications of the proposed designs.

  12. Lensless Fourier-Transform Ghost Imaging with Classical Incoherent Light

    E-Print Network [OSTI]

    Minghui Zhang; Qing Wei; Xia Shen; Yongfeng Liu; Honglin Liu; Jing Cheng; Shensheng Han

    2006-05-22T23:59:59.000Z

    The Fourier-Transform ghost imaging of both amplitude-only and pure-phase objects was experimentally observed with classical incoherent light at Fresnel distance by a new lensless scheme. The experimental results are in good agreement with the standard Fourier-transform of the corresponding objects. This scheme provides a new route towards aberration-free diffraction-limited 3D images with classically incoherent thermal light, which have no resolution and depth-of-field limitations of lens-based tomographic systems.

  13. Light Activated Self-Propelled Colloids

    E-Print Network [OSTI]

    J. Palacci; S. Sacanna; S. -H. Kim; G. -R. Yi; D. J. Pine; P. M. Chaikin

    2014-10-27T23:59:59.000Z

    Light-activated self-propelled colloids are synthesized and their active motion is studied using optical microscopy. We propose a versatile route using different photoactive materials, and demonstrate a multiwavelength activation and propulsion. Thanks to the photoelectrochemical properties of two semiconductor materials (\\alpha Fe2 O3 and TiO2 ), a light with an energy higher than the bandgap triggers the reaction of decomposition of hydrogen peroxide and produces a chemical cloud around the particle. It induces a phoretic attraction with neighbouring colloids as well as an osmotic self- propulsion of the particle on the substrate. We use these mechanisms to form colloidal cargos as well as self-propelled particles where the light-activated component is embedded into a dielectric sphere. The particles are self-propelled along a direction otherwise randomized by thermal fluctuations, and exhibit a persistent random walk. For sufficient surface density, the particles spontaneously form "living crystals" which are mobile, break apart and reform. Steering the particle with an external magnetic field, we show that the formation of the dense phase results from the collisions heads-on of the particles. This effect is intrinsically non-equilibrium and a novel principle of organization for systems without detailed balance. Engineering families of particles self-propelled by different wavelength demonstrate a good understanding of both the physics and the chemistry behind the system and points to a general route for designing new families of self-propelled particles.

  14. Superposed Coherent and Squeezed Light

    E-Print Network [OSTI]

    Fesseha Kassahun

    2012-01-18T23:59:59.000Z

    We first calculate the mean photon number and quadrature variance of superposed coherent and squeezed light, following a procedure of analysis based on combining the Hamiltonians and using the usual definition for the quadrature variance of superposed light beams. This procedure of analysis leads to physically unjustifiable mean photon number of the coherent light and quadrature variance of the superposed light. We then determine both of these properties employing a procedure of analysis based on superposing the Q functions and applying a slightly modified definition for the quadrature variance of a pair of superposed light beams. We find the expected mean photon number of the coherent light and the quadrature variance of the superposed light. Moreover, the quadrature squeezing of the superposed output light turns out to be equal to that of the superposed cavity light.

  15. Nonclassicality of Thermal Radiation

    E-Print Network [OSTI]

    Lars M. Johansen

    2004-02-16T23:59:59.000Z

    It is demonstrated that thermal radiation of small occupation number is strongly nonclassical. This includes most forms of naturally occurring radiation. Nonclassicality can be observed as a negative weak value of a positive observable. It is related to negative values of the Margenau-Hill quasi-probability distribution.

  16. Thermal Reactor Safety

    SciTech Connect (OSTI)

    Not Available

    1980-06-01T23:59:59.000Z

    Information is presented concerning fire risk and protection; transient thermal-hydraulic analysis and experiments; class 9 accidents and containment; diagnostics and in-service inspection; risk and cost comparison of alternative electric energy sources; fuel behavior and experiments on core cooling in LOCAs; reactor event reporting analysis; equipment qualification; post facts analysis of the TMI-2 accident; and computational methods.

  17. Thermal barrier coating

    DOE Patents [OSTI]

    Bowker, Jeffrey Charles (Gibsonia, PA); Sabol, Stephen M. (Orlando, FL); Goedjen, John G. (Oviedo, FL)

    2001-01-01T23:59:59.000Z

    A thermal barrier coating for hot gas path components of a combustion turbine based on a zirconia-scandia system. A layer of zirconium scandate having the hexagonal Zr.sub.3 Sc.sub.4 O.sub.12 structure is formed directly on a superalloy substrate or on a bond coat formed on the substrate.

  18. Low thermal conductivity skutterudites

    SciTech Connect (OSTI)

    Fleurial, J.P.; Caillat, T.; Borshchevsky, A.

    1997-07-01T23:59:59.000Z

    Recent experimental results on semiconductors with the skutterudite crystal structure show that these materials possess attractive transport properties and have a good potential for achieving ZT values substantially larger than for state-of-the-art thermoelectric materials. Both n-type and p-type conductivity samples have been obtained, using several preparation techniques. Associated with a low hole effective mass, very high carrier mobilities, low electrical resistivities and moderate Seebeck coefficients are obtained in p-type skutterudites. For a comparable doping level, the carrier mobilities of n-type samples are about an order of magnitude lower than the values achieved on p-type samples. However, the much larger electron effective masses and Seebeck coefficients on p-type samples. However, the much larger electron effective masses and Seebeck coefficients make n-type skutterudite promising candidates as well. Unfortunately, the thermal conductivities of the binary skutterudites compounds are too large, particularly at low temperatures, to be useful for thermoelectric applications. Several approaches to the reduction of the lattice thermal conductivity in skutterudites are being pursued: heavy doping, formation of solid solutions and alloys, study of novel ternary and filled skutterudite compounds. All those approaches have already resulted in skutterudite compositions with substantially lower thermal conductivity values in these materials. Recently, superior thermoelectric properties in the moderate to high temperature range were achieved for compositions combining alloying and filling of the skutterudite structure. Experimental results and mechanisms responsible for low thermal conductivity in skutterudites are discussed.

  19. Thermal Infrared Remote Sensing

    E-Print Network [OSTI]

    to us, like reflective ("nearreflective ("near--" infrared (0.7" infrared (0.7 -- 3.03.0 µµm)m) andand near-infrared far infrared ultraviolet Thermal Infrared refers to region o EM spectrum from ~3 - 14 µm.landscape. IMPORTANT: NEARIMPORTANT: NEAR--INFRARED is short enough wavelength toINFRARED is short enough wavelength

  20. Solar thermal financing guidebook

    SciTech Connect (OSTI)

    Williams, T.A.; Cole, R.J.; Brown, D.R.; Dirks, J.A.; Edelhertz, H.; Holmlund, I.; Malhotra, S.; Smith, S.A.; Sommers, P.; Willke, T.L.

    1983-05-01T23:59:59.000Z

    This guidebook contains information on alternative financing methods that could be used to develop solar thermal systems. The financing arrangements discussed include several lease alternatives, joint venture financing, R and D partnerships, industrial revenue bonds, and ordinary sales. In many situations, alternative financing arrangements can significantly enhance the economic attractiveness of solar thermal investments by providing a means to efficiently allocate elements of risk, return on investment, required capital investment, and tax benefits. A net present value approach is an appropriate method that can be used to investigate the economic attractiveness of alternative financing methods. Although other methods are applicable, the net present value approach has advantages of accounting for the time value of money, yielding a single valued solution to the financial analysis, focusing attention on the opportunity cost of capital, and being a commonly understood concept that is relatively simple to apply. A personal computer model for quickly assessing the present value of investments in solar thermal plants with alternative financing methods is presented in this guidebook. General types of financing arrangements that may be desirable for an individual can be chosen based on an assessment of his goals in investing in solar thermal systems and knowledge of the individual's tax situation. Once general financing arrangements have been selected, a screening analysis can quickly determine if the solar investment is worthy of detailed study.

  1. High-Temperature Thermal Array for Next Generation Solar Thermal...

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

    3 Q1 High-Temperature Thermal Array for Next Generation Solar Thermal Power Production - FY13 Q1 This document summarizes the progress of this Los Alamos National Laboratory...

  2. Effective Thermal Conductivity of Graded Nanocomposites with Interfacial Thermal

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    Effective Thermal Conductivity of Graded Nanocomposites with Interfacial Thermal Resistance H Engineering, Newmark Laboratory, 205 North Mathews Avenue, University of Illinois at Urbana-Champaign, Urbana, IL 61801 Department of Civil and Environmental Engineering, 4139 Engineering Gateway, University

  3. High Energy Density Thermal Batteries: Thermoelectric Reactors for Efficient Automotive Thermal Storage

    SciTech Connect (OSTI)

    None

    2011-11-15T23:59:59.000Z

    HEATS Project: Sheetak is developing a new HVAC system to store the energy required for heating and cooling in EVs. This system will replace the traditional refrigerant-based vapor compressors and inefficient heaters used in today’s EVs with efficient, light, and rechargeable hot-and-cold thermal batteries. The high energy density thermal battery—which does not use any hazardous substances—can be recharged by an integrated solid-state thermoelectric energy converter while the vehicle is parked and its electrical battery is being charged. Sheetak’s converters can also run on the electric battery if needed and provide the required cooling and heating to the passengers—eliminating the space constraint and reducing the weight of EVs that use more traditional compressors and heaters.

  4. Transformations in Lighting: The Ninth Annual Solid-State Lighting...

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

    in DOE's "Transformations in Lighting" Solid-State Lighting (SSL) R&D Workshop. DOE SSL Portfolio Manager James Brodrick kicked off Day 1 by observing that although LED...

  5. 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 Li, Lingling Jin, Wei Wu, Sheldon X.-D. Tan, Jun Yang Department of Electrical Engineering temperature by dynamic thermal managements becomes necessary. This paper proposes a novel approach

  6. Light cone matrix product

    SciTech Connect (OSTI)

    Hastings, Matthew B [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

  7. Nonequilibrium lighting plasmas

    SciTech Connect (OSTI)

    Dakin, J.T. (GE Lighting, Nela Park, Cleveland, OH (US))

    1991-12-01T23:59:59.000Z

    In this paper the science of a variety of devices employing nonequilibrium lighting plasmas is reviewed. The devices include the fluorescent lamp, the low-pressure sodium lamp, the neon sign, ultraviolet lamps, glow indicators, and a variety of devices used by spectroscopists, such as the hollow cathode light source. The plasma conditions in representative commercial devices are described. Recent research on the electron gas, the role of heavy particles, spatial and temporal inhomogeneities, and new electrodeless excitation schemes is reviewed. Areas of future activity are expected to be in new applications of high-frequency electronics to commercial devices, new laser-based diagnostics of plasma conditions, and more sophisticated models requiring more reliable and extensive rate coefficient data.

  8. The Advanced Light Source

    SciTech Connect (OSTI)

    Jackson, A.

    1991-05-01T23:59:59.000Z

    The Advanced Light Source (ALS), a national user facility currently under construction at the Lawrence Berkeley Laboratory (LBL), is a third-generation synchrotron light source designed to produce extremely bright beams of synchrotron radiation in the energy range from a few eV to 10 keV. The design is based on a 1--1.9-GeV electron storage ring (optimized at 1.5 GeV), and utilizes special magnets, known as undulators and wigglers (collectively referred to as insertion devices), to generate the radiation. The facility is scheduled to begin operating in April 1993. In this paper we describe the progress in the design, construction, and commissioning of the accelerator systems, insertion devices, and beamlines. Companion presentations at this conference give more detail of specific components in the ALS, and describe the activities towards establishing an exciting user program. 3 figs., 2 tabs.

  9. Scattering Of Light Nuclei

    SciTech Connect (OSTI)

    Quaglioni, S; Navratil, P; Roth, R

    2009-12-15T23:59:59.000Z

    The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.

  10. Fusion pumped light source

    DOE Patents [OSTI]

    Pappas, Daniel S. (Los Alamos, NM)

    1989-01-01T23:59:59.000Z

    Apparatus is provided for generating energy in the form of light radiation. A fusion reactor is provided for generating a long, or continuous, pulse of high-energy neutrons. The neutron flux is coupled directly with the lasing medium. The lasing medium includes a first component selected from Group O of the periodic table of the elements and having a high inelastic scattering cross section. Gamma radiation from the inelastic scattering reactions interacts with the first component to excite the first component, which decays by photon emission at a first output wavelength. The first output wavelength may be shifted to a second output wavelength using a second liquid component responsive to the first output wavelength. The light outputs may be converted to a coherent laser output by incorporating conventional optics adjacent the laser medium.

  11. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01T23:59:59.000Z

    High temperature underground thermal energy storage, inProceedings, Thermal Energy Storage in Aquifers Workshop:underground thermal energy storage, in ATES newsletter:

  12. THERMAL ENERGY STORAGE IN AQUIFERS WORKSHOP

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01T23:59:59.000Z

    Survey of Thermal Energy Storage in Aquifers Coupled withconcept of thermal energy storage in aquifers was suggestedLow Temperature Thermal Energy Storage Program of Oak Ridge

  13. Ocean Thermal Extractable Energy Visualization: Final Technical...

    Office of Environmental Management (EM)

    Ocean Thermal Extractable Energy Visualization: Final Technical Report Ocean Thermal Extractable Energy Visualization: Final Technical Report Report about the Ocean Thermal...

  14. OCEAN THERMAL ENERGY CONVERSION PROGRAMMATIC ENVIRONMENTAL ASSESSMENT

    E-Print Network [OSTI]

    Sands, M.Dale

    2013-01-01T23:59:59.000Z

    M.D. (editor) Ocean Thermal Energy Conversion (OTEC) Draftin Ocean Thermal Energy Conversion (OTEC) technology haveThe Ocean Thermal Energy Conversion (OTEC) 2rogrammatic

  15. THERMAL ENERGY STORAGE IN AQUIFERS WORKSHOP

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01T23:59:59.000Z

    Survey of Thermal Energy Storage in Aquifers Coupled withAnnual Thermal Energy Storage Contractors' InformationLarge-Scale Thermal Energy Storage for Cogeneration and

  16. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01T23:59:59.000Z

    1978, High temperature underground thermal energy storage,in Proceedings, Thermal Energy Storage in Aquifers Workshop:High temperature underground thermal energy storage, in ATES

  17. Phonon plasmon interaction in ternary group-III-nitrides Ronny Kirste, Stefan Mohn, Markus R. Wagner, Juan S. Reparaz, and Axel Hoffmann

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonon plasmon interaction in ternary group-III-nitrides Ronny Kirste, Stefan Mohn, Markus R investigated by electron energy-loss spectroscopy J. Chem. Phys. 137, 114508 (2012) Plasmon resonances and electron transport in linear sodium atomic chains J. Appl. Phys. 112, 053707 (2012) Plasmon coupling

  18. Decay of zone-center phonons in AlN with A1, E1, and E2 symmetries P. Pandit, D. Y. Song, and M. Holtza

    E-Print Network [OSTI]

    Holtz, Mark

    electron gases in field effect transistors. This results in significant local self-heating1,2 which into traveling acoustic waves to dissipate energy from the imme- diate self-heating region. Understanding the intrinsic phonon decay properties of high-quality crystalline materials is thus fundamental to self-heating

  19. Journal of Applied Physics --March 1, 2001 --Volume 89, Issue 5, pp. 2932-2938 Phonon heat conduction in a semiconductor nanowire

    E-Print Network [OSTI]

    in the nonequilibrium phonon distribution due to partially diffuse boundary scattering. Numerical simulation. The value of this decrease and its interface roughness and temperature dependence are different from. Quantum Electron. 6, 511 (2000). [INSPEC] 7.X. Sun, Z. Zhang, and M. S. Dresselhaus, Appl. Phys. Lett. 74

  20. arXiv:1108.6120v3[cond-mat.mes-hall]5Mar2012 Colloquium: Phononics: Manipulating heat flow with electronic analogs and

    E-Print Network [OSTI]

    Li, Baowen

    with electronic analogs and beyond Nianbei Li,1, 2, 3 Jie Ren,2, 4 Lei Wang,5, 2 Gang Zhang,6, 2 Peter H¨anggi,2 of Physics, Renmin University of China, Beijing 100872, P. R. China 6 Department of Electronics, Peking derives from lattice vibrations, i.e. the phonons, is usually considered as waste energy and, moreover