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Sample records for lighting phonons thermal

  1. Manipulation of Thermal Phonons 

    E-Print Network [OSTI]

    Hsu, Chung-Hao

    2013-03-28

    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. Acoustic phonon spectrum and thermal transport in nanoporous alumina arrays

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

    Kargar, Fariborz; Ramirez, Sylvester; Debnath, Bishwajit; Malekpour, Hoda; Lake, Roger; Balandin, Alexander A.

    2015-10-28

    We report results of a combined investigation of thermal conductivity and acoustic phonon spectra in nanoporous alumina membranes with the pore diameter decreasing from D=180 nm to 25 nm. The samples with the hexagonally arranged pores were selected to have the same porosity Ø ?13%. The Brillouin-Mandelstam spectroscopy measurements revealed bulk-like phonon spectrum in the samples with D=180-nm pores and spectral features, which were attributed to spatial confinement, in the samples with 25-nm and 40-nm pores. The velocity of the longitudinal acoustic phonons was reduced in the samples with smaller pores. As a result, analysis of the experimental data andmore »calculated phonon dispersion suggests that both phonon-boundary scattering and phonon spatial confinement affect heat conduction in membranes with the feature sizes D« less

  3. Reconstructing phonon mean-free-path contributions to thermal conductivity using nanoscale membranes

    E-Print Network [OSTI]

    Cuffe, John

    Knowledge of the mean-free-path distribution of heat-carrying phonons is key to understanding phonon-mediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide ...

  4. Thermal Memory: A Storage of Phononic Information Lei Wang1,2

    E-Print Network [OSTI]

    Li, Baowen

    Thermal Memory: A Storage of Phononic Information Lei Wang1,2 and Baowen Li2,3,* 1 Department element for a computer in addition to logic gates. In this Letter we report a model of thermal memory. We demonstrate via numerical simulation that thermal (phononic) information stored in the memory can be retained

  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)

    2014-12-15

    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. Thermal conductivity in large-J two-dimensional antiferromagnets: Role of phonon scattering

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

    Chernyshev, A. L.; Brenig, Wolfram

    2015-08-05

    Different types of relaxation processes for magnon heat current are discussed, with a particular focus on coupling to three-dimensional phonons. There is thermal conductivity by these in-plane magnetic excitations using two distinct techniques: Boltzmann formalism within the relaxation-time approximation and memory-function approach. Also considered are the scattering of magnons by both acoustic and optical branches of phonons. We demonstrate an accord between the two methods, regarding the asymptotic behavior of the effective relaxation rates. It is strongly suggested that scattering from optical or zone-boundary phonons is important for magnon heat current relaxation in a high-temperature window of ?D?Tmore »« less

  7. Excitation of phonons in a Bose-Einstein condensate by light scattering Light scattering imparts momentum to the condensate and creates an excitation (which

    E-Print Network [OSTI]

    Excitation of phonons in a Bose-Einstein condensate by light scattering Light scattering imparts momentum to the condensate and creates an excitation (which can be a phonon or a free particle). A detailed study of the scattered light should therefore reveal a detailed picture of the Bose condensate similar

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

    E-Print Network [OSTI]

    Bockrath, Marc

    Ballistic Phonon Thermal Transport in Multiwalled Carbon Nanotubes H.-Y. Chiu,1 V. V. Deshpande,1 H Physics, California Institute of Technology, Pasadena, California 91125, USA 2 Department of Physics, University of California, Riverside, California 92521, USA 3 IPMC/SB, E´cole Polytechnique Fe´de´rale de

  9. Phononic crystal devices

    DOE Patents [OSTI]

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

    2012-01-10

    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.

  10. 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.

    2008-01-01

    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.

  11. Phonon softening and metallization of a narrow-gap semiconductor by thermal disorder

    SciTech Connect (OSTI)

    Delaire, Olivier A [ORNL; Marty, Karol J [ORNL; Stone, Matthew B [ORNL; Kent, Paul R [ORNL; Lucas, [ORNL; Abernathy, Douglas L [ORNL; Mandrus, David [ORNL; Sales, Brian C [ORNL

    2011-01-01

    The vibrations of ions in solids at finite temperature depend on interatomic force-constants that result from electrostatic interactions between ions, and the response of the electron density to atomic displacements. At high temperatures, vibration amplitudes are substantial, and electronic states are affected, thus modifying the screening properties of the electron density. By combining inelastic neutron scattering measurements of Fe$_{1-x}$Co$_x$Si as a function of temperature, and finite-temperature first-principles calculations including thermal disorder effects, we show that the coupling between phonons and electronic structure results in an anomalous temperature dependence of phonons. The strong concomitant renormalization of the electronic structure induces the semiconductor-to-metal transition that occurs with increasing temperature in FeSi. Our results show that for systems with rapidly changing electronic densities of states at the Fermi level, there are likely to be significant phonon-electron interactions, resulting in anomalous temperature dependent properties.

  12. Introducing thermally stable inter-tube defects to assist off-axial phonon transport in carbon nanotube films

    SciTech Connect (OSTI)

    Wang, Jing [Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Chen, Di; Wallace, Joseph; Gigax, Jonathan; Wang, Xuemei [Department of Nuclear Engineering, Texas A and M University, College Station, Texas, 77843 (United States); Shao, Lin, E-mail: lshao@tamu.edu [Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Department of Nuclear Engineering, Texas A and M University, College Station, Texas, 77843 (United States)

    2014-05-12

    Through integrated molecular dynamics (MD) simulations and experimental studies, we demonstrated the feasibility of an ion-irradiation-and-annealing based phonon engineering technique to enhance thermal conductivity of carbon nanotube (CNT) films. Upon ion irradiation of CNT films, both inter-tube defects and intra-tube defects are introduced. Our MD simulations show that inter-tube defects created between neighboring tubes are much more stable than intra-tube defects created on tube graphitic planes. Upon thermal annealing, intra-tube defects are preferentially removed but inter-tube defects stay. Consequently, axial phonon transport increases due to reduced phonon scattering and off-axial phonon transport is sustained due to the high stability of inter-tube defects, leading to a conductivity enhancement upon annealing. The modeling predictions agree with experimental observations that thermal conductivities of CNT films were enhanced after 2?MeV hydrogen ion irradiations and conductivities were further enhanced upon post irradiation annealing.

  13. 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)

    2014-06-30

    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.

  14. 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

    2013-05-07

    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.

  15. Thermal pumping of light-emitting diodes

    E-Print Network [OSTI]

    Gray, Dodd (Dodd J.)

    2011-01-01

    The work presented here is a study of thermally enhanced injection in light-emitting diodes (LEDs). This effect, which we refer to as "thermal pumping", results from Peltier energy exchange from the lattice to charge ...

  16. 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)

    2014-02-21

    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.

  17. 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

    2015-01-01

    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)%.

  18. 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...

  19. Phonon manipulation with phononic crystals.

    SciTech Connect (OSTI)

    Kim Bongsang; Hopkins, Patrick Edward; Leseman, Zayd C.; Goettler, Drew F.; Su, Mehmet F.; El-Kady, Ihab Fathy; Reinke, Charles M.; Olsson, Roy H., III

    2012-01-01

    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.

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

    E-Print Network [OSTI]

    Young-Wook Cho; Yoon-Ho Kim

    2010-07-12

    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.

  1. Thermal Logic Gates: Computation with Phonons and Baowen Li1,2

    E-Print Network [OSTI]

    Li, Baowen

    transport phenomena with similar importance in nature [1], electric conduction and thermal conduction have that control electric flow has led to an impressive technological development that has changed many aspects of temperature-dependent power spectra in nonlinear lattices [8­15], and molecular level thermal machines

  2. 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

  3. Optical characterization of complex mechanical and thermal transport properties

    E-Print Network [OSTI]

    Johnson, Jeremy A. (Jeremy Andrew)

    2011-01-01

    Time-resolved impulsive stimulated light scattering (ISS), also known as transient grating spectroscopy, was used to investigate phonon mediated thermal transport in semiconductors and mechanical degrees of freedom linked ...

  4. Phonons and defects in semiconductors and nanostructures: Phonon trapping, phonon scattering, and heat flow at heterojunctions

    SciTech Connect (OSTI)

    Estreicher, S. K., E-mail: Stefan.Estreicher@ttu.edu; Gibbons, T. M.; Kang, By.; Bebek, M. B. [Physics Department, Texas Tech University, Lubbock, Texas 79409-1051 (United States)

    2014-01-07

    Defects in semiconductors introduce vibrational modes that are distinct from bulk modes because they are spatially localized in the vicinity of the defect. Light impurities produce high-frequency modes often visible by Fourier-transform infrared absorption or Raman spectroscopy. Their vibrational lifetimes vary by orders of magnitude and sometimes exhibit unexpectedly large isotope effects. Heavy impurities introduce low-frequency modes sometimes visible as phonon replicas in photoluminescence bands. But other defects such as surfaces or interfaces exhibit spatially localized modes (SLMs) as well. All of them can trap phonons, which ultimately decay into lower-frequency bulk phonons. When heat flows through a material containing defects, phonon trapping at localized modes followed by their decay into bulk phonons is usually described in terms of phonon scattering: defects are assumed to be static scattering centers and the properties of the defect-related SLMs modes are ignored. These dynamic properties of defects are important. In this paper, we quantify the concepts of vibrational localization and phonon trapping, distinguish between normal and anomalous decay of localized excitations, discuss the meaning of phonon scattering in real space at the atomic level, and illustrate the importance of phonon trapping in the case of heat flow at Si/Ge and Si/C interfaces.

  5. 3rd Order Temporal Correlation Function of Pseudo-Thermal Light

    E-Print Network [OSTI]

    Yu Zhou; Jianbin Liu; Yanhua Shih

    2009-09-18

    This experiment reports a nontrivial third-order temporal correlation of chaotic-thermal light in which the randomly radiated thermal light is observed to have a 6-times greater chance of being captured by three individual photodetectors simultaneously than that of being captured by three photodetectors at different times (separated by the coherent time of pseudo-thermal light), indicating a "three-photon bunching" effect. The nontrivial correlation of thermal light is the result of multi-photon interference.

  6. 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

  7. 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

    2013-12-10

    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.

  8. 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

  9. Phonon-hopping thermal conduction in quantum dot superlattices Manu Shamsa, Weili Liu, and Alexander A. Balandina

    E-Print Network [OSTI]

    of California--Riverside, Riverside, California 92521 Jianlin Liu Quantum Structures Laboratory, Department of Electrical Engineering, University of California--Riverside, Riverside, California 92521 Received 18 April or polycrystalline materials in terms of thermal transport. © 2005 American Institute of Physics. DOI: 10

  10. Thermal Management of Solar Cells

    E-Print Network [OSTI]

    Saadah, Mohammed Ahmed

    2013-01-01

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

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

    E-Print Network [OSTI]

    Landon, Colin D.

    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 ...

  12. Theory of Light Emission in Sonoluminescence as Thermal Radiation

    E-Print Network [OSTI]

    Wang-Kong Tse; P. T. Leung

    2006-06-14

    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.

  13. Phonon interference effects in molecular junctions

    SciTech Connect (OSTI)

    Markussen, Troels

    2013-12-28

    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.

  14. 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

  15. 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

  16. 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

  17. Lifetime of the phonons in the PLT ceramic

    SciTech Connect (OSTI)

    Barba-Ortega, J. Joya, M. R.; Londońo, F. A.

    2014-11-05

    The lifetimes at higher temperatures on lanthanum-modified lead titanate (PLT) are mainly due to the anharmonic decay of optical phonons into low-energy phonons. The temperature-independent contributions from inherent crystal defects and from boundary scattering become comparable to the phonon scattering contribution at lower temperatures. The thermal interaction is large at higher temperatures which decreases the phonon mean free path, and so the decay lifetime decreases as the temperature of the system is increased. This leads to the increased line width at higher temperatures. We made an estimate of the lifetimes for different concentrations and temperatures in PLT.

  18. Phonon transport in perovskite SrTiO3 from first principles

    E-Print Network [OSTI]

    Feng, Lei; Shiomi, Junichiro

    2015-01-01

    We investigate phonon transport in perovskite strontium titanate (SrTiO3) which is stable above its phase transition temperature (~105 K) by using first-principles molecular dynamics and anharmonic lattice dynamics. Unlike conventional ground-state-based perturbation methods that give imaginary phonon frequencies, the current calculation reproduces stable phonon dispersion relations observed in experiments. We find the contribution of optical phonons to overall lattice thermal conductivity is larger than 60%, markedly different from the usual picture with dominant contribution from acoustic phonons. The mode- and pseudopotential-dependence analysis suggests the strong attenuation of acoustic phonons transport originated from strong anharmonic coupling with the transversely-polarized ferroelectric modes.

  19. 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 Politčcnica de Valčncia, 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)

    2014-09-07

    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.

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

    E-Print Network [OSTI]

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

    2008-01-07

    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.

  1. Wide Area Thermal Processing of Light Emitting Materials

    SciTech Connect (OSTI)

    Duty, Chad E; Joshi, Pooran C; Jellison Jr, Gerald Earle; Angelini, Joseph Attilio; Sabau, Adrian S

    2011-10-01

    Laboratory laser materials synthesis of wide bandgap materials has been successfully used to create white light emitting materials (LEMs). This technology development has progressed to the exploration on design and construction of apparatus for wide area doping and phase transformation of wide bandgap material substrates. The objective of this proposal is to develop concepts for wide area doping and phase transformation based on AppliCote Associates, LLC laser technology and ORNL high density pulsed plasma arc technology.

  2. Light transport in cold atoms and thermal decoherence

    E-Print Network [OSTI]

    Guillaume Labeyrie; Dominique Delande; Robin Kaiser; Christian Miniatura

    2006-03-17

    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.

  3. Synthetic thermoelectric materials comprising phononic crystals

    DOE Patents [OSTI]

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

    2013-08-13

    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.

  4. Hybrid optical-thermal devices and materials for light manipulation and radiative cooling

    E-Print Network [OSTI]

    Boriskina, Svetlana V; Hsu, Wei-Chun; Weinstein, Lee; Huang, Xiaopeng; Loomis, James; Xu, Yanfei; Chen, Gang

    2015-01-01

    We report on optical design and applications of hybrid meso-scale devices and materials that combine optical and thermal management functionalities owing to their tailored resonant interaction with light in visible and infrared frequency bands. We outline a general approach to designing such materials, and discuss two specific applications in detail. One example is a hybrid optical-thermal antenna with sub-wavelength light focusing, which simultaneously enables intensity enhancement at the operating wavelength in the visible and reduction of the operating temperature. The enhancement is achieved via light recycling in the form of whispering-gallery modes trapped in an optical microcavity, while cooling functionality is realized via a combination of reduced optical absorption and radiative cooling. The other example is a fabric that is opaque in the visible range yet highly transparent in the infrared, which allows the human body to efficiently shed energy in the form of thermal emission. Such fabrics can find...

  5. Hypersonic phononic crystals

    E-Print Network [OSTI]

    Gorishnyy, Taras

    2007-01-01

    Manipulation of the distribution of phonons inM a solid is important for both basic science and applications ranging from heat management to reduction of noise in electronic circuits and creating materials with superior ...

  6. Phonon scattering in graphene over substrate steps

    SciTech Connect (OSTI)

    Sevinçli, H., E-mail: haldunsevincli@iyte.edu.tr [Department of Materials Science and Engineering, Izmir Institute of Technology, Gülbahçe Kampüsü, 35430 Urla, Izmir (Turkey); Department of Micro- and Nano-technology (DTU Nanotech), Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Brandbyge, M., E-mail: mads.brandbyge@nanotech.dtu.dk [Department of Micro- and Nano-technology (DTU Nanotech), Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Center for Nanostructured Graphene (CNG), Department of Micro- and Nano-technology, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)

    2014-10-13

    We calculate the effect on phonon transport of substrate-induced bends in graphene. We consider bending induced by an abrupt kink in the substrate, and provide results for different step-heights and substrate interaction strengths. We find that individual substrate steps reduce thermal conductance in the range between 5% and 47%. We also consider the transmission across linear kinks formed by adsorption of atomic hydrogen at the bends and find that individual kinks suppress thermal conduction substantially, especially at high temperatures. Our analysis show that substrate irregularities can be detrimental for thermal conduction even for small step heights.

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

    SciTech Connect (OSTI)

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

    2014-06-09

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

  8. Enhancing phonon transmission across a Si/Ge interface by atomic roughness: First-principles study with the Green's function method

    E-Print Network [OSTI]

    Tian, Zhiting

    Knowledge on phonon transmittance as a function of phonon frequency and incidence angle at interfaces is vital for multiscale modeling of heat transport in nanostructured materials. Although thermal conductivity reduction ...

  9. Thermal-Light-Induced Coherent Dynamics in Atoms and Molecules -- an Exact Quantum Mechanical Treatment

    E-Print Network [OSTI]

    David Avisar; Asaf Eilam; A. D. Wilson-Gordon

    2015-05-01

    The question of whether sunlight induces coherent dynamics in biological systems is under debate. Here we show, on the basis of an exact fully quantum mechanical treatment, that thermal light induces excited-state coherences in matter similar to those induced by a coherent state. We demonstrate the phenomenon on a V-type model system and a two-state Born-Oppenheimer molecular system. Remarkably, wavepacket-like dynamics is induced in the excited molecular potential-energy surface.

  10. Phonon mean free path of graphite along the c-axis

    SciTech Connect (OSTI)

    Wei, Zhiyong; Yang, Juekuan; Chen, Weiyu; 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); Li, Deyu, E-mail: deyu.li@vanderbilt.edu [Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1592 (United States)

    2014-02-24

    Phonon transport in the c-axis direction of graphite thin films has been studied using non-equilibrium molecular dynamics (MD) simulation. The simulation results show that the c-axis thermal conductivities for films of thickness ranging from 20 to 500 atomic layers are significantly lower than the bulk value. Based on the MD data, a method is developed to construct the c-axis thermal conductivity as an accumulation function of phonon mean free path (MFP), from which we show that phonons with MFPs from 2 to 2000?nm contribute ?80% of the graphite c-axis thermal conductivity at room temperature, and phonons with MFPs larger than 100?nm contribute over 40% to the c-axis thermal conductivity. These findings indicate that the commonly believed value of just a few nanometers from the simple kinetic theory drastically underestimates the c-axis phonon MFP of graphite.

  11. Low-dimensional phonon transport effects in ultra-narrow, disordered graphene nanoribbons

    E-Print Network [OSTI]

    1 Low-dimensional phonon transport effects in ultra-narrow, disordered graphene nanoribbons Hossein-narrow armchair graphene nanoribbons (GNRs) using non-equilibrium Green's function (NEGF) simulation techniques, despite their relatively high phonon group velocities. Keywords: graphene nanoribbons, thermal conductance

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

    E-Print Network [OSTI]

    Xu, Peng

    2010-01-01

    Control of Building Thermal Storage. ” ASHRAE TransactionsControl of Building Thermal Storage. ” ASHRAE Transactionsto how fast the passive thermal storage can be charged and

  13. Phonon dispersion in graphene

    E-Print Network [OSTI]

    L. A. Falkovsky

    2007-08-11

    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.

  14. Microscopic mechanism of low thermal conductivity in lead telluride

    SciTech Connect (OSTI)

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

    2012-01-01

    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.

  15. Temperature-dependent carrier–phonon coupling in topological insulator Bi{sub 2}Se{sub 3}

    SciTech Connect (OSTI)

    Lai, Yi-Ping; Liu, Jia-Ming; Chen, Hsueh-Ju; Wu, Kuang-Hsiung

    2014-12-08

    Temperature-dependent (11.0?K?294.5?K) carrier–phonon coupling in Bi{sub 2}Se{sub 3} is investigated by ultrafast pump?probe spectroscopy. The rise time of the differential reflectivity is interpreted by a combined effect of electron temperature relaxation and hot-phonon lifetime. The electron?phonon coupling constant of the bulk state (?=0.63±0.05) is deduced from theoretical fitting. Increasing hot-phonon lifetime with decreasing temperature is attributed to a decreasing phonon?phonon collision rate. A complete analysis of the thermalization process is presented. Understanding carrier and phonon dynamics is essential for future optoelectronic and spintronic applications of topological insulators.

  16. 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

    2009-01-01

    /z=2x10 -4 #1;I/z=10 -3 #1;I/z=10 -2 #1;I/z=0.1 FIG. 2. #1;Color online#2; HBT effect for different ?I / z?=10?4 , 2#5;10?4 ,10?3 ,10?2, and 0.1 #1;from top to below#2;, with ?g=10 and z?=105. WANG et al. PHYSICAL REVIEW A 79, 033835 #1;2009...#2; ?I / z?1=0.2, with ?g=4, #1;d#2; ?I / z?1=0.2 and ?g=1, and #1;e#2; ?I / z?1=0.2 and ?g=0.1. HANBURY BROWN?TWISS EFFECT AND THERMAL LIGHT? PHYSICAL REVIEW A 79, 033835 #1;2009#2; 033835-3 and one-third. The more information in the object...

  17. Thermal conductivity of bulk nanostructured lead telluride

    E-Print Network [OSTI]

    Hori, Takuma

    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 ...

  18. Giant Anharmonic Phonon Scattering in PbTe

    SciTech Connect (OSTI)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL; Marty, Karol J [ORNL; May, Andrew F [ORNL; McGuire, Michael A [ORNL; Singh, David J [ORNL; Lumsden, Mark D [ORNL; Sales, Brian C [ORNL; Du, Mao-Hua [ORNL; Ehlers, Georg [ORNL; Podlesnyak, Andrey A [ORNL

    2011-01-01

    Understanding the microscopic processes affecting the bulk thermal conductivity is crucial to develop more efficient thermoelectric materials. PbTe is currently one of the leading thermoelectric materials, largely thanks to its low thermal conductivity. However, the origin of this low thermal conductivity in a simple rocksalt structure has so far been elusive. Using a combination of inelastic neutron scattering measurements and first-principles computations of the phonons, we identify a strong anharmonic coupling between the ferroelectric transverse optic (TO) mode and the longitudinal acoustic (LA) modes in PbTe. This interaction extends over a large portion of reciprocal space, and directly affects the heat-carrying LA phonons. The LA-TO anharmonic coupling is likely to play a central role in explaining the low thermal conductivity of PbTe. The present results provide a microscopic picture of why many good thermoelectric materials are found near a lattice instability of the ferroelectric type.

  19. Temporal stability of blue phosphorescent organic light-emitting diodes affected by thermal annealing of emitting layers

    E-Print Network [OSTI]

    Chen, Shaw H.

    Temporal stability of blue phosphorescent organic light-emitting diodes affected by thermal morphological instability as part of the challenge to the PhOLED device lifetime. Introduction Blue. In addition to the need for efficient and stable blue emitters,1,2 the technological advances in blue Ph

  20. Structure of crystalline oxide ceramics studied by phonon spectroscopy

    SciTech Connect (OSTI)

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

    2013-03-31

    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)

  1. 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)

    2014-01-13

    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.

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

    E-Print Network [OSTI]

    Seung-il Nam

    2015-03-04

    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 $\\mu=0$.

  3. 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 ...

  4. 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

    2014-01-01

    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.

  5. 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

  6. Multiscale thermal transport.

    SciTech Connect (OSTI)

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

    2004-02-01

    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.

  7. 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)

    2014-10-28

    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.

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

    SciTech Connect (OSTI)

    Walczak, Kamil; Yerkes, Kirk L.

    2014-05-07

    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.

  9. 817 2014 Materials Research Society MRS BULLETIN VOLUME 39 SEPTEMBER 2014 www.mrs.org/bulletin Phonons and phonon engineering in

    E-Print Network [OSTI]

    -dimensional (2D) material systems such as graphene, the out-of-plane transverse vibrations are denoted as z, affect the thermal, electrical, optical, and mechanical properties of solids.1 In semiconductors phonons are the main heat carriers in electrical insulators and semiconductors. Long-wavelength acoustic

  10. Phonon dispersion of graphene revisited

    SciTech Connect (OSTI)

    Sahoo, Rasmita, E-mail: sahoorasmita@yahoo.com; Mishra, Rashmi Ranjan [Birla Institute of Technology and Science, Department of Physics (India)

    2012-05-15

    The phonon dispersion of graphene is derived by using a simple mass spring model and considering up to the first, second, third, and fourth nearest-neighbor interactions. The results obtained from different nearest-neighbor interactions are compared and it is shown that the k{sup 2} dependence for the out-of-plane transverse acoustic mode obtained in other sophisticated methods as well as experiment occurs only after including the fourth nearest-neighbor interaction.

  11. 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)

    2014-02-01

    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.

  12. realizing such unusual thermalization is con-fining the light in one direction, so that every

    E-Print Network [OSTI]

    Asbury, Chip

    to nanokelvin temperatures in magnetic traps. The textbook example of what this can allow is Bose­Einstein- conductivity. The Weitz group has observed Bose­Einstein condensation of light, in remarkably close analogy as atoms, even to the point of Bose­Einstein condensation, illustrates a broader theme in current physics

  13. 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.

    2013-05-31

    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

  14. 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 ...

  15. Thermal neutron steady-state spectra in light water reactor fuel assemblies poisoned with various non-1/v absorbers of different concentrations

    SciTech Connect (OSTI)

    Swaminathan, K.; Chandra, S.; Jha, R.C.; Tewari, S.P. )

    1991-07-01

    This paper reports on the thermal neutron scattering kernel that explicitly incorporates the presence of chemical binding energy and the collective oscillations in the dynamics of water, the steady-state thermal neutron spectra in light water reactor fuel assemblies poisoned with non-1/v absorbers, such as cadmium, samarium, erbium, and gadolinium, in various concentrations have been computed at 298 K. The calculated spectra are in reasonable agreement with the corresponding experimental spectra for realistic source terms.

  16. Probing Light Thermal Dark-Matter With a Higgs Portal Mediator

    E-Print Network [OSTI]

    Gordan Krnjaic

    2015-12-13

    We systematically study light (portal and identify the remaining gaps in the viable parameter space. Such models require a comparably light scalar mediator that mixes with the Higgs to avoid DM overproduction and can be classified according to whether this mediator decays (in)visibly. In a representative benchmark model with Dirac fermion DM, we find that, even with conservative assumptions about the DM-mediator coupling and mass ratio, the regime in which the mediator is heavier than the DM is fully ruled out by a combination of collider, rare meson decay, and direct detection limits; future and planned experiments including NA62 can further improve sensitivity to scenarios in which the Higgs portal interaction does not determine the DM abundance. The opposite, regime in which the mediator is lighter than the DM and the latter annihilates to pairs of visibly-decaying mediators is still viable, but much of the parameter space is covered by rare meson decay, supernova cooling, beam dump, and direct detection constraints. Nearly all of these conclusions apply broadly to the simplest variations (e.g. scalar or asymmetric DM). Future experiments including SHiP, NEWS, and Super-CDMS SNOLAB can greatly improve coverage to this class of models.

  17. PHYSICAL REVIEW B 85, 035438 (2012) Enhancing and tuning phonon transport at vibrationally mismatched solid-solid interfaces

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    2012-01-01

    mismatched solid-solid interfaces Timothy S. English,* John C. Duda, Justin L. Smoyer, Donald A. Jordan received 11 December 2011; published 23 January 2012) The thermal conductance of interfaces plays a major interfacial phonon transport as well as the ability to predict thermal interface conductance. However, despite

  18. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousand CubicResourcelogo and-E C H N13,CenterCenterLighting Sign In

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

    E-Print Network [OSTI]

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

    2014-01-01

    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.

  20. 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

    2014-09-19

    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.

  1. Reduction of heat capacity and phonon group velocity in silicon nanowires Christopher Marchbanks and Zhigang Wua)

    E-Print Network [OSTI]

    Wu, Zhigang

    Reduction of heat capacity and phonon group velocity in silicon nanowires Christopher Marchbanks distributions, resulting in an 15% to 23% reduction in heat capacity and an averaged decrease of 31% in acoustic thermoelectrics,10,11 photovoltaic cells,12,13 and light-emitting diodes.14 Nanowire structure and confinement

  2. 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)

    2014-07-21

    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.

  3. Effects of phonon-phonon coupling on properties of pygmy resonance in $^{124-132}$Sn

    E-Print Network [OSTI]

    N. N. Arsenyev; A. P. Severyukhin; V. V. Voronov; Nguyen Van Giai

    2012-09-27

    Starting from an effective Skyrme interaction we study effects of phonon-phonon coupling on the low-energy electric dipole response in $^{124-132}$Sn. The QRPA calculations are performed within a finite rank separable approximation. The inclusion of two-phonon configurations gives a considerable contribution to low-lying strength. Comparison with available experimental data shows a reasonable agreement for the low-energy $E1$ strength distribution.

  4. Phonon polariton interaction with patterned materials

    E-Print Network [OSTI]

    Statz, Eric R. (Eric Robert)

    2008-01-01

    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 ...

  5. Study of Phonon Modes in Germanium Nanowires

    E-Print Network [OSTI]

    Xi Wang; Ali Shakouri; Bin Yu; Xuhui Sun; Meyya Meyyappan

    2007-02-25

    The observation of pure phonon confinement effect in germanium nanowires is limited due to the illumination sensitivity of Raman spectra. In this paper we measured Raman spectra for different size germanium nanowires with different excitation laser powers and wavelengths. By eliminating the local heating effect, the phonon confinement effect for small size nanowires was clearly identified. We have also fitted the Raman feature changes to estimate the size distribution of nanowires for the first time.

  6. Phonon cooling by an optomechanical heat pump

    E-Print Network [OSTI]

    Ying Dong; F. Bariani; P. Meystre

    2015-07-27

    We propose and analyze theoretically a cavity optomechanical analog of a heat pump that uses a polariton fluid to cool mechanical modes coupled to a single pre-cooled phonon mode via external modulation of the substrate of the mechanical resonator. This approach permits to cool phonon modes of arbitrary frequencies not limited by the cavity-optical field detuning deep into the quantum regime from room temperature.

  7. Phonon cooling by an optomechanical heat pump

    E-Print Network [OSTI]

    Ying Dong; F. Bariani; P. Meystre

    2015-12-04

    We propose and analyze theoretically a cavity optomechanical analog of a heat pump that uses a polariton fluid to cool mechanical modes coupled to a single pre-cooled phonon mode via external modulation of the substrate of the mechanical resonator. This approach permits to cool phonon modes of arbitrary frequencies not limited by the cavity-optical field detuning deep into the quantum regime from room temperature.

  8. Ultralow Thermal Conductivity in Organoclay Nanolaminates Synthesized via Simple Self-Assembly

    E-Print Network [OSTI]

    Braun, Paul

    Information ABSTRACT: Because interfaces impede phonon transport of thermal energy, nanostructuring canUltralow Thermal Conductivity in Organoclay Nanolaminates Synthesized via Simple Self-Assembly Mark of Chemistry, University of Illinois, Urbana Illinois 61801, United States § Materials and Manufacturing

  9. Experimental and numerical investigation of phonon mean free path distribution

    E-Print Network [OSTI]

    Zeng, Lingping

    2013-01-01

    Knowledge of phonon mean free path (MFP) distribution is critically important to engineering size effects. Phenomenological models of phonon relaxation times can give us some sense about the mean free path distribution, ...

  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)

    2014-10-28

    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. Electron-phonon coupling and electron heat capacity of metals under conditions of strong electron-phonon nonequilibrium

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    Electron-phonon coupling and electron heat capacity of metals under conditions of strong electron of the strength of the electron-phonon coupling and the electron heat capacity on the electron temperature electron-phonon nonequilibrium. These conditions are characteristic of metal targets subjected to energetic

  12. Electronic, phononic, and thermoelectric properties of graphyne sheets

    SciTech Connect (OSTI)

    Sevinçli, Hâldun; Sevik, Cem

    2014-12-01

    Electron, phonon, and thermoelectric transport properties of ?-, ?-, ?-, and 6,6,12-graphyne sheets are compared and contrasted with those of graphene. ?-, ?-, and 6,6,12-graphynes, with direction dependent Dirac dispersions, have higher electronic transmittance than graphene. ?-graphyne also attains better electrical conduction than graphene except at its band gap. Vibrationally, graphene conducts heat much more efficiently than graphynes, a behavior beyond an atomic density differences explanation. Seebeck coefficients of the considered Dirac materials are similar but thermoelectric power factors decrease with increasing effective speeds of light. ?-graphyne yields the highest thermoelectric efficiency with a thermoelectric figure of merit as high as ZT?=?0.45, almost an order of magnitude higher than that of graphene.

  13. Long range optical phonons in liquid water

    E-Print Network [OSTI]

    Elton, Daniel C

    2015-01-01

    In this work we show that on subpicosecond time scales optical phonon modes can propagate through the H-bond network of water over relatively long distances (2-4 nm). Using molecular dynamics simulation we find propagating optical phonons in the librational and OH stretching bands. The OH stretching phonon only appears when a polarizable model (TTM3-F) is employed. Both of these phonon modes exhibit LO-TO splitting at $k = 0$, indicating long range dipole-dipole interactions in the system. We study the LO-TO splitting as a function of temperature, finding that the splitting increases for the librational mode at higher temperatures but decreases for the stretching mode. Since LO-TO splitting is intimately connected to structure, this analysis opens the door for new insights into how the local structure of water changes with temperature. Our results also explain a previously unnoticed discrepancy one encounters when comparing the librational peaks found in Raman and IR/dielectric spectra. Previously the three R...

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

    SciTech Connect (OSTI)

    Hansom, Jack; Schulte, Carsten H. H.; Matthiesen, Clemens; Stanley, Megan J.; Atatüre, Mete

    2014-10-27

    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. THERMAL TRANSPORT IN SELF-ASSEMBLED NANOSTRUCTURES IAN PEARSON BLITZ

    E-Print Network [OSTI]

    Braun, Paul

    THERMAL TRANSPORT IN SELF-ASSEMBLED NANOSTRUCTURES BY IAN PEARSON BLITZ THESIS Submitted in partial Understanding of phonon mediated thermal transport properties in nanostructured materials is essential of the thermal transport properties of model organic- inorganic, nanoscopically layered systems for the purpose

  16. Study of decoherence in models for hard-core bosons coupled to optical phonons

    E-Print Network [OSTI]

    A. Dey; M. Q. Lone; S. Yarlagadda

    2014-12-18

    Understanding coherent dynamics of excitons, spins, or hard-core bosons (HCBs) has tremendous scientific and technological implications for light harvesting and quantum computation. Here, we study decay of excited-state population and decoherence in two models for HCBs, namely: an infinite-range HCB model governed by Markovian dynamics and a two-site HCB model with site-dependent strong potentials and subject to non-Markovian dynamics. Both models are investigated in the regimes of antiadiabaticity and strong HCB-phonon coupling with each site providing a different local optical phonon environment; furthermore, the HCB systems in both models are taken to be initially uncorrelated with the environment in the polaronic frame of reference. For the infinite-range model, we derive an effective many-body Hamiltonian that commutes with the long-range system Hamiltonian and thus has the same set of eigenstates; consequently, a quantum-master-equation approach shows that the quantum states of the system do not decohere. In the case of the two-site HCB model, we show clearly that the degree of decoherence and decay of excited state are enhanced by the proximity of the site-energy difference to the eigenenergy of phonons and are most pronounced when the site-energy difference is at resonance with twice the polaronic energy; additionally, the decoherence and the decay effects are reduced when the strength of HCB-phonon coupling is increased. Even for a multimode situation, the degree of decoherence and decay are again dictated by the nearness of the energy difference to the allowed phonon mode eigenenergies.

  17. Giant Thermal Rectification from Polyethylene Nanofiber Thermal Diodes

    E-Print Network [OSTI]

    Zhang, Teng

    2015-01-01

    The realization of phononic computing is held hostage by the lack of high performance thermal devices. Here we show through theoretical analysis and molecular dynamics simulations that unprecedented thermal rectification factors (as large as 1.20) can be achieved utilizing the phase dependent thermal conductivity of polyethylene nanofibers. More importantly, such high thermal rectifications only need very small temperature differences (< 20 oC) across the device, which is a significant advantage over other thermal diodes which need temperature biases on the order of the operating temperature. Taking this into consideration, we show that the dimensionless temperature-scaled rectification factors of the polymer nanofiber diodes range from 12 to 25 - much larger than other thermal diodes (< 8). The polymer nanofiber thermal diode consists of a crystalline portion whose thermal conductivity is highly phase-sensitive and a cross-linked portion which has a stable phase. Nanoscale size effect can be utilized t...

  18. Tunable ultrasonic phononic crystal controlled by infrared radiation

    SciTech Connect (OSTI)

    Walker, Ezekiel; Neogi, Arup, E-mail: zhmwang@gmail.com, E-mail: arup@unt.edu [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054 (China); University of North Texas, Department of Physics, Denton, Texas 76201 (United States); Reyes, Delfino [University of North Texas, Department of Physics, Denton, Texas 76201 (United States); Universidad Autónoma del Estado de México, Toluca 50120 (Mexico); Rojas, Miguel Mayorga [Universidad Autónoma del Estado de México, Toluca 50120 (Mexico); Krokhin, Arkadii [University of North Texas, Department of Physics, Denton, Texas 76201 (United States); Wang, Zhiming, E-mail: zhmwang@gmail.com, E-mail: arup@unt.edu [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2014-10-06

    A tunable phononic crystal based ultrasonic filter was designed by stimulating the phase of the polymeric material embedded in a periodic structure using infrared radiation. The acoustic filter can be tuned remotely using thermal stimulation induced by the infrared radiation. The filter is composed of steel cylinder scatterers arranged periodically in a background of bulk poly (N-isopropylacrylamide) polymer hydrogel. The lattice structure creates forbidden bands for certain sets of mechanical waves that cause it to behave as an ultrasonic filter. Since the bandstructure is determined by not only the arrangement of the scatterers but also the physical properties of the materials composing the scatterers and background, modulating either the arrangement or physical properties will alter the effect of the crystal on propagating mechanical waves. Here, the physical properties of the filter are varied by inducing changes in the polymer hydrogel using an electromagnetic thermal stimulus. With particular focus on the k{sub 00}-wave, the transmission of ultrasonic wave changes by as much as 20 dBm, and band widths by 22% for select bands.

  19. 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 Borzenets, I. V.; Coskun, U. C.; Mebrahtu, H. T.; Bomze, Yu. V.; Smirnov, A. I.; Finkelstein, G....

  20. Evidence for coupling between collective state and phonons in...

    Office of Scientific and Technical Information (OSTI)

    for coupling between collective state and phonons in two-dimensional charge-density-wave systems Citation Details In-Document Search Title: Evidence for coupling between...

  1. 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)

    2014-10-21

    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.

  2. A Parametric Study of the Thermal-Hydraulic Response of Supercritical Light Water Reactors During Loss-of-Feedwater and Turbine-Trip Events

    SciTech Connect (OSTI)

    Cliff B. Davis; Jacopo Buongiorno; Philip E. MacDonald

    2003-09-01

    The Idaho National Engineering and Environmental Laboratory in investigating the feasibility of supercritical light water reactors for low-cost electric power production through a Nuclear Energy Research Initiative Project sponsored by the United State Department of Energy. The project is evaluating a variety of technical issues related to the fuel and reactor design, material corrosion, and safety characteristics. This paper presents the results of parametric calculations using the RELAP5 computer code to characterize the thermal-hydraulic response of supercritical reactors to transients initiated by loss-of-feedwater and turbine-trip events. The purpose of the calculations was to aid in the design of the safety systems by determining the time available for the safety systems to respond and their required capacities.

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

    SciTech Connect (OSTI)

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

    2014-07-07

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

  4. Non-destructive selective probing of phononic excitations in a cold Bose gas using impurities

    E-Print Network [OSTI]

    D. Hangleiter; M. T. Mitchison; T. H. Johnson; M. Bruderer; M. B. Plenio; D. Jaksch

    2014-12-26

    We introduce a detector that selectively probes the phononic excitations of a cold Bose gas. The detector is composed of a single impurity atom confined by a double-well potential, where the two lowest eigenstates of the impurity form an effective probe qubit that is coupled to the phonons via density-density interactions with the bosons. The system is analogous to a two-level atom coupled to photons of the radiation field. We demonstrate that tracking the evolution of the qubit populations allows probing both thermal and coherent excitations in targeted phonon modes. The targeted modes are selected in both energy and momentum by adjusting the impurity's potential. We show how to use the detector to observe coherent density waves and to measure temperatures of the Bose gas down to the nano-Kelvin regime. We analyze how our scheme could be realized experimentally, including the possibility of using an array of multiple impurities to achieve greater precision from a single experimental run.

  5. Generalized phononic networks : of length scales, symmetry breaking and (non) locality : "controlling complexity through simplicity"

    E-Print Network [OSTI]

    Koh, Cheong Yang (Cheong Yang Henry)

    2011-01-01

    The manipulation and control of phonons is extremely important from both a fundamental scientific and applied technological standpoint, providing applications ranging from sound insulation to heat management. Phononic ...

  6. 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)

    2014-01-14

    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.

  7. 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

  8. ORIGINAL PAPER Modeling of Phonon Wind Shielding Effects on Moving

    E-Print Network [OSTI]

    Marks, Laurence D.

    ORIGINAL PAPER Modeling of Phonon Wind Shielding Effects on Moving Dislocation Arrays A. M interaction is employed to simulate the shielding of phonon wind drag in moving dislocation arrays. In the model, we use assumptions that overestimate the shielding effect to calculate an upper bound

  9. Experimental study of thermal conductivity reduction of silicon-germanium nanocomposite for thermoelastic application

    E-Print Network [OSTI]

    Lee, Hohyun, 1978-

    2005-01-01

    To improve the thermoelectric energy conversion efficiency of silicon germanium (SiGe), two methods were used to decrease the thermal conductivity by increasing phonon boundary scattering at interfaces. In the first method, ...

  10. Optical transient grating measurements of micro/nanoscale thermal transport and mechanical properties

    E-Print Network [OSTI]

    Eliason, Jeffrey Kristian

    2015-01-01

    The laser-based transient grating technique was used to study phonon mediated thermal transport in bulk and nanostructured semiconductors and surface wave propagation in a monolayer of micron sized spheres. In the transient ...

  11. 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)

    2014-02-15

    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.

  12. Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes

    E-Print Network [OSTI]

    1 Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes Stefanie Wolf1 transport in Si nanomeshes. Phonons are treated semiclassically as particles of specific energy and velocity, ii) the roughness amplitude of the pore surfaces on the thermal conductivity of the nanomeshes. We

  13. 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)

    2014-10-13

    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.

  14. Phonon Quasidiffusion in Cryogenic Dark Matter Search Large Germanium Detectors

    SciTech Connect (OSTI)

    Leman, S.W.; /MIT, MKI; Cabrera, B.; /Stanford U., Phys. Dept.; McCarthy, K.A.; /MIT, MKI; Pyle, M.; /Stanford U., Phys. Dept.; Resch, R.; /SLAC; Sadoulet, B.; Sundqvist, K.M.; /LBL, Berkeley; Brink, P.L.; Cherry, M.; /Stanford U., Phys. Dept.; Do Couto E Silva, E.; /SLAC; Figueroa-Feliciano, E.; /MIT, MKI; Mirabolfathi, N.; Serfass, B.; /UC, Berkeley; Tomada, A.; /Stanford U., Phys. Dept.

    2012-06-04

    We present results on quasidiffusion studies in large, 3 inch diameter, 1 inch thick [100] high purity germanium crystals, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare data obtained in two different detector types, with different phonon sensor area coverage, with results from a Monte Carlo. The Monte Carlo includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels.

  15. Influence of pulse width and detuning on coherent phonon generation

    E-Print Network [OSTI]

    Nakamura, Kazutaka G; Kayanuma, Yosuke

    2015-01-01

    We investigated the coherent phonon generation mechanism by irradiation of an ultrashort pulse with a simple two-level model. Our derived formulation shows that both impulsive stimulated Raman scattering (ISRS) and impulsive absorption (IA) simultaneously occur, and phonon wave packets are generated in the electronic ground and excited states by ISRS and IA, respectively. We identify the dominant process from the amplitude of the phonon oscillation. For short pulse widths, ISRS is very small and becomes larger as the pulse width increases. We also show that the initial phase is dependent on the pulse width and the detuning.

  16. Phonon densities of states and related thermodynamic properties of high temperature ceramics.

    SciTech Connect (OSTI)

    Loong, C.-K.

    1998-08-28

    Structural components and semiconductor devices based on silicon nitride, aluminum nitride and gallium nitride are expected to function more reliably at elevated temperatures and at higher levels of performance because of the strong atomic bonding in these materials. The degree of covalency, lattice specific heat, and thermal conductivity are important design factors for the realization of advanced applications. We have determined the phonon densities of states of these ceramics by the method of neutron scattering. The results provide a microscopic interpretation of the mechanical and thermal properties. Moreover, experimental data of the static, structures, and dynamic excitations of atoms are essential to the validation of interparticle potentials employed for molecular-dynamics simulations of high-temperature properties of multi-component ceramic systems. We present an overview of neutron-scattering investigations of the atomic organization, phonon excitations, as well as calculations of related thermodynamic properties of Si{sub 3}N{sub 4}, {beta}-sialon, AlN and GaN. The results are compared with those of the oxide analogs such as SiO{sub 2} and Al{sub 2}O{sub 3}.

  17. ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect

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

    Liu, Wenyan; Zhang, Yu; Ruan, Cheng; Wang, Dan; Zhang, Tieqiang; Feng, Yi; Gao, Wenzhu; Yin, Jingzhi; Wang, Yiding; Riley, Alexis P.; et al

    2015-01-01

    The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0?lm/W for red, 47.1?lm/W for yellow, and 62.4?lm/W for green LEDs at 2.6?V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to themore »low emission temperature coefficients of 0.022, 0.050, and 0.068?nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs.« less

  18. Ab initio study of electron-phonon interaction in phosphorene

    E-Print Network [OSTI]

    Liao, Bolin

    The monolayer of black phosphorus, or “phosphorene,” has recently emerged as a two-dimensional semiconductor with intriguing highly anisotropic transport properties. Existing calculations of its intrinsic phonon-limited ...

  19. Interfacial Electron-Phonon Coupling as the Cause of Enhanced...

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

    Interfacial Electron-Phonon Coupling as the Cause of Enhanced Tc in Single-layer FeSe Films on SrTiO3 Friday, February 27, 2015 In the past several years, multiple studies have...

  20. Design of materials Configurations for enhanced phononic and electronic properties

    E-Print Network [OSTI]

    Daraio, Chiara

    2006-01-01

    phononic crystals with PTFE beads; (b) Schematic drawing of59 Figure 27. Solitary waves in PTFE chaingenerated by PTFE ball-striker with a velocity of 2 m/s: (a)

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

    SciTech Connect (OSTI)

    D.W. Lynch

    2004-09-30

    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.

  2. Electronic Structure, Phonon Dynamical Properties, and CO2 Capture...

    Office of Scientific and Technical Information (OSTI)

    Electronic Structure, Phonon Dynamical Properties, and CO2 Capture Capability of Na2-xMxZrO3 ( MLi ,K): Density-Functional Calculations and Experimental Validations Citation...

  3. Electronic Structure, Phonon Dynamical Properties, and CO2 Capture...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Electronic Structure, Phonon Dynamical Properties, and CO2 Capture Capability of Na2-xMxZrO3 ( MLi ,K): Density-Functional Calculations and Experimental...

  4. 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

    2014-09-02

    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.

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

    E-Print Network [OSTI]

    S. Frauendorf

    2007-10-24

    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.

  6. Thermal properties of microscale inorganic light-emitting diodes in a pulsed Yuhang Li, Yan Shi, Jizhou Song, Chaofeng Lu, Tae-il Kim et al.

    E-Print Network [OSTI]

    Rogers, John A.

    LEDs to be operated by pulsed current (or power) to take advantage of their high efficiency, thermal (LEDs) in a pulsed operation offer combined characteristics in efficiency, thermal management and experiments, is developed to study the thermal properties of micro-scale inorganic LEDs (l-ILED) in a pulsed

  7. 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

    2006-02-07

    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.

  8. 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 ...

  9. Thermal trim for luminaire

    DOE Patents [OSTI]

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

    2013-11-19

    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. Toward Single Electron Resolution Phonon Mediated Ionization Detectors

    E-Print Network [OSTI]

    Nader Mirabolfathi; H. Rusty Harris; Rupak Mahapatra; Kyle Sundqvist; Andrew Jastram; Bruno Serfass; Dana Faiez; Bernard Sadoulet

    2015-10-04

    Experiments seeking to detect rare event interactions such as dark matter or coherent elastic neutrino nucleus scattering are striving for large mass detectors with very low detection threshold. Using Neganov-Luke phonon amplification effect, the Cryogenic Dark Matter Search (CDMS) experiment is reaching unprecedented RMS resolutions of ~ 14 eV$_{ee}$ . CDMSlite is currently the most sensitive experiment to WIMPs of mass $\\sim$5 GeV/c$^{2}$ but is limited in achieving higher phonon gains due to an early onset of leakage current into Ge crystals. The contact interface geometry is particularly weak for blocking hole injection from the metal, and thus a new design is demonstrated that allows high voltage bias via vacuum separated electrode. With an increased bias voltage and a $\\times$ 2 Luke phonon gain, world best RMS resolution of sigma $\\sim$7 eV$_{ee}$ for 0.25 kg (d=75 mm, h=1 cm) Ge detectors was achieved. Since the leakage current is a function of the field and the phonon gain is a function of the applied voltage, appropriately robust interface blocking material combined with thicker substrate (25 mm) will reach a resolution of $\\sim$2.8 eV$_{ee}$. In order to achieve better resolution of $\\sim$ eV, we are investigating a layer of insulator between the phonon readout surface and the semiconductor crystals.

  11. Thermal Bogoliubov transformation in nuclear structure theory

    E-Print Network [OSTI]

    A. I. Vdovin; Alan A. Dzhioev

    2010-01-20

    Thermal Bogoliubov transformation is an essential ingredient of the thermo field dynamics -- the real time formalism in quantum field and many-body theories at finite temperatures developed by H. Umezawa and coworkers. The approach to study properties of hot nuclei which is based on the extension of the well-known Quasiparticle-Phonon Model to finite temperatures employing the TFD formalism is presented. A distinctive feature of the QPM-TFD combination is a possibility to go beyond the standard approximations like the thermal Hartree-Fock or the thermal RPA ones.

  12. Contact thermal lithography

    E-Print Network [OSTI]

    Schmidt, Aaron Jerome, 1979-

    2004-01-01

    Contact thermal lithography is a method for fabricating microscale patterns using heat transfer. In contrast to photolithography, where the minimum achievable feature size is proportional to the wavelength of light used ...

  13. Evolution of the phonon density of states of LaCoO3 over the...

    Office of Scientific and Technical Information (OSTI)

    Evolution of the phonon density of states of LaCoO3 over the spin state transition Citation Details In-Document Search Title: Evolution of the phonon density of states of LaCoO3...

  14. Overcoming phonon-induced dephasing for indistinguishable photon sources

    E-Print Network [OSTI]

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

    2012-06-25

    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.

  15. Ti(III) Doped Titanium Dioxide: an Effective Strategy to Improve the Visible Light Photocatalytic Activity

    E-Print Network [OSTI]

    Zuo, Fan

    2012-01-01

    achieve the detrapping electrons are thermal activation andnon-thermal activation such as sub-bandgap light excitation.

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

    SciTech Connect (OSTI)

    Jo, Insun; Ou, Eric; Shi, Li; Pettes, Michael Thompson; Wu, Wei

    2014-05-19

    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.

  17. Preface to special topic: Selected articles from phononics 2013: The second international conference on phononic crystals/metamaterials, phonon transport and optomechanics, 2-7 June 2013, Sharm El-Sheikh, Egypt

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

    Hussein, Mahmoud I.; El-Kady, Ihab; Li, Baowen; Sánchez-Dehesa, José

    2014-12-31

    Phononics” is an interdisciplinary branch of physics and engineering that deals with the behavior of phonons, and more broadly elastic and acoustic waves in similar context, and their manipulation in solids and/or fluids to benefit technological applications. Compared to resembling disciplines, such as electronics and photonics, phononics is a youthful field. It is growing at a remarkable rate, especially when viewed liberally with no limiting constraints on any particular length scale, discipline or application.

  18. ISSN:1369 7021 Elsevier Ltd 2012JUNE 2012 | VOLUME 15 | NUMBER 6266 Phononics in

    E-Print Network [OSTI]

    -layer graphene via Raman spectroscopy. Uniqueness of phonon transport in two-dimensional (2D) materials materials. Acoustic phonons are the main heat carriers in insulators and semiconductors. The long. In bulk semiconductors with g atoms per unit cell, there are 3g phonon dispersion branches for each q

  19. Active Thermal Extraction of Near-field Thermal Radiation

    E-Print Network [OSTI]

    Ding, Ding

    2015-01-01

    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.

  20. Thermal excitation of d band electrons in Au: implications for laser-induced phase transformations

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    Thermal excitation of d band electrons in Au: implications for laser-induced phase transformations of the electron heat capacity and the electron-phonon coupling factor are investigated for Au based on the electron density of states obtained from ab initio electronic structure calculations. Thermal excitation

  1. Phonon-enhanced crystal growth and lattice healing

    DOE Patents [OSTI]

    Buonassisi, Anthony; Bertoni, Mariana; Newman, Bonna

    2013-05-28

    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.

  2. Phonon statistics in an acoustical resonator coupled to a pumped two-level emitter

    E-Print Network [OSTI]

    Victor Ceban; Mihai A. Macovei

    2015-02-04

    The concept of an acoustical analog of the optical laser has been developed recently both in theoretical as well as experimental works. We discuss here a model of a coherent phonon generator with a direct signature of quantum properties of the sound vibrations. The considered setup is made of a laser driven quantum dot (QD) embedded in an acoustical nanocavity. The system's dynamics is solved for a single phonon mode in the steady-state and in the strong QD-phonon coupling regime beyond the secular approximation. We demonstrate that the phonon statistics exhibits quantum features, i.e. sub-Poissonian phonon statistics.

  3. Comparative study of the electronic structure, phonon spectra, and electron-phonon interaction of ZrB2 and TiB2

    SciTech Connect (OSTI)

    Sichkar, S. M. [Institute of Metal Physics; Antonov, V. N. [Ames Laboratory; Antropov, V. P. [Ames Laboratory

    2013-02-28

    The electronic structure, optical and x-ray absorption spectra, angledependence of the cyclotron masses and extremal cross sections of the Fermisurface, phonon spectra, electron-phonon Eliashberg and transport spectralfunctions, temperature dependence of electrical resistivity of the MB2 (M=Tiand Zr) diborides were investigated from first principles using the fullpotential linear muffin-tin orbital method. The calculations of the dynamicmatrix were carried out within the framework of the linear response theory. Agood agreement with experimental data of optical and x-ray absorption spectra,phonon spectra, electron-phonon spectral functions, electrical resistivity,cyclotron masses and extremal cross sections of the Fermi surface was achieved.

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

    SciTech Connect (OSTI)

    Gautreau, Pierre; Chu, Yanbiao; Basaran, Cemal; Ragab, Tarek

    2014-06-28

    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.

  5. Quantifying electron-phonon coupling in CdTe12xSex nanocrystals via coherent phonon manipulation

    E-Print Network [OSTI]

    Xu, Xianfan

    challenges. Third generation photovoltaic (PV) technology is one of the areas where NCs have been employed to take advantage of confinement enhanced phenomena such as multi-exciton generation (MEG) and hot and made attempts to quantify ultrafast optically generated coherent phonons in NCs. However, none has

  6. High Thermal Efficiency and Low Emissions with Supercritical...

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

    High Thermal Efficiency and Low Emissions with Supercritical Gasoline Injection-Ignition in a Light Duty Engine High Thermal Efficiency and Low Emissions with Supercritical...

  7. 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

    2011-11-02

    '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.

  8. Frequency-Dependent Photothermal Measurement of Transverse Thermal Diffusivity of Organic Semiconductors

    E-Print Network [OSTI]

    J. W. Brill; Maryam Shahi; Marcia M. Payne; Jesper Edberg; Y. Yao; Xavier Crispin; J. E. Anthony

    2015-09-08

    We have used a photothermal technique, in which chopped light heats the front surface of a small ( ~ 1 mm2) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid nitrogen cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side-groups, carry most of the heat.

  9. Frequency-Dependent Photothermal Measurement of Transverse Thermal Diffusivity of Organic Semiconductors

    E-Print Network [OSTI]

    J. W. Brill; Maryam Shahi; Marcia M. Payne; Jesper Edberg; Y. Yao; Xavier Crispin; J. E. Anthony

    2015-08-13

    We have used a photothermal technique, in which chopped light heats the front surface of a small ( ~ 1 mm2) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid nitrogen cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side-groups, carry most of the heat.

  10. Beyond the Replacement Paradigm: Smart Lighting

    E-Print Network [OSTI]

    Salama, Khaled

    Hole? · DC device in an AC Powered World · Cool light source with thermal issues · High Efficacy ­ High Spectral Density Information Informationneeded to makethe Light SMART #12;10 Light Flow ­ InformationBeyond the Replacement Paradigm: Smart Lighting Robert F. Karlicek, Jr. Director, Smart Lighting

  11. Thermal Resonance Fusion

    E-Print Network [OSTI]

    Dong, Bao-Guo

    2015-01-01

    We first show a possible mechanism to create a new type of nuclear fusion, thermal resonance fusion, i.e. low energy nuclear fusion with thermal resonance of light nuclei or atoms, such as deuterium or tritium. The fusion of two light nuclei has to overcome the Coulomb barrier between these two nuclei to reach up to the interacting region of nuclear force. We found nuclear fusion could be realized with thermal vibrations of crystal lattice atoms coupling with light atoms at low energy by resonance to overcome this Coulomb barrier. Thermal resonances combining with tunnel effects can greatly enhance the probability of the deuterium fusion to the detectable level. Our low energy nuclear fusion mechanism research - thermal resonance fusion mechanism results demonstrate how these light nuclei or atoms, such as deuterium, can be fused in the crystal of metal, such as Ni or alloy, with synthetic thermal vibrations and resonances at different modes and energies experimentally. The probability of tunnel effect at dif...

  12. The change of microstructure and thermal properties in ion irradiated carbon nanotube mats as a function of ion penetration depth

    SciTech Connect (OSTI)

    Aitkaliyeva, A. [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States)] [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Shao, L. [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States) [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States)

    2013-02-11

    A stack of three carbon nanotube (CNT) mats was irradiated with 3 MeV He ions. The change in structural and thermal properties of individual mats as a function of ion penetration depth was characterized using electron microscopy and laser flash techniques. Ion irradiation can enhance thermal conductivity of the mats by introducing inter-tube displacements, which improve phonon transport across adjacent nanotubes. The enhancement, however, is reduced at higher damage levels due to the increasing phonon-defect scattering within the tubes. This study demonstrates the feasibility of using ion irradiation to manipulate thermal transport in carbon nanotubes.

  13. 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.

    1995-07-01

    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.

  14. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    oxygen compounds (19) cathodes (17) physics of elementary particles and fields (17) solar (photovoltaic), solar (thermal), solid state lighting, phonons, thermal conductivity,...

  15. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Text1 Citations11 Multimedia0 Datasets0 Filter Results Filter by Subject solar (photovoltaic), solar (thermal), solid state lighting, phonons, thermal conductivity,...

  16. Catalytic thermal barrier coatings

    DOE Patents [OSTI]

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

    2009-06-02

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

  17. Phonons in a one-dimensional microfluidic crystal

    E-Print Network [OSTI]

    Tsevi Beatus; Tsvi Tlusty; Roy Bar-Ziv

    2010-08-06

    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.

  18. Spin-phonon coupling in scandium doped gallium ferrite

    SciTech Connect (OSTI)

    Chakraborty, Keka R. E-mail: smyusuf@barc.gov.in; Mukadam, M. D.; Basu, S.; Yusuf, S. M. E-mail: smyusuf@barc.gov.in; Paul, Barnita; Roy, Anushree; Grover, Vinita; Tyagi, A. K.

    2015-03-28

    We embarked on a study of Scandium (Sc) doped (onto Ga site) gallium ferrite (GaFeO{sub 3}) and found remarkable magnetic properties. In both doped as well as parent compounds, there were three types of Fe{sup 3+} ions (depending on the symmetry) with the structure conforming to space group Pna2{sub 1} (Sp. Grp. No. 33) below room temperature down to 5?K. We also found that all Fe{sup 3+} ions occupy octahedral sites, and carry high spin moment. For the higher Sc substituted sample (Ga{sub 1?x}Sc{sub x}FeO{sub 3}: x?=?0.3), a canted magnetic ordered state is found. Spin-phonon coupling below Néel temperature was observed in doped compounds. Our results indicated that Sc doping in octahedral site modifies spin-phonon interactions of the parent compound. The spin-phonon coupling strength was estimated for the first time in these Sc substituted compounds.

  19. Phonon-deficit effect in superconductors in a strong microwave field

    SciTech Connect (OSTI)

    Gulyan, A.M.; Zharkov, G.F.

    1981-08-20

    The phonon flux from a thin superconducting film irradiated by a microwave field is derived. It is shown that in intense microwave fields, as in the case of weak fields, studied previously )A. M. Gulian (Gulyan) and G. F. Zharkov, Phys. Lett. 80A, 79 (1980); Zh. Eksp. Teor. Fiz. 80, 303 (1981) (Sov. Phys. JETP 53, 154 (1981))), phonons are not emitted in a narrow spectral interval of phonon frequencies and are instead absorbed from the heat reservoir by the film.

  20. Thermal trim for a luminaire

    DOE Patents [OSTI]

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

    2013-02-19

    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.

  1. Light-Light Scattering

    E-Print Network [OSTI]

    Naohiro Kanda

    2011-06-03

    For a long time, it is believed that the light by light scattering is described properly by the Lagrangian density obtained by Heisenberg and Euler. Here, we present a new calculation which is based on the modern field theory technique. It is found that the light-light scattering is completely different from the old expression. The reason is basically due to the unphysical condition (gauge condition) which was employed by the QED calcualtion of Karplus and Neumann. The correct cross section of light-light scattering at low energy of $(\\frac{\\omega}{m} \\ll 1)$ can be written as $ \\displaystyle{\\frac{d\\sigma}{d\\Omega}=\\frac{1}{(6\\pi)^2}\\frac{\\alpha^4} {(2\\omega)^2}(3+2\\cos^2\\theta +\\cos^4\\theta)}$.

  2. Thermal Resonance Fusion

    E-Print Network [OSTI]

    Bao-Guo Dong

    2015-07-07

    We first show a possible mechanism to create a new type of nuclear fusion, thermal resonance fusion, i.e. low energy nuclear fusion with thermal resonance of light nuclei or atoms, such as deuterium or tritium. The fusion of two light nuclei has to overcome the Coulomb barrier between these two nuclei to reach up to the interacting region of nuclear force. We found nuclear fusion could be realized with thermal vibrations of crystal lattice atoms coupling with light atoms at low energy by resonance to overcome this Coulomb barrier. Thermal resonances combining with tunnel effects can greatly enhance the probability of the deuterium fusion to the detectable level. Our low energy nuclear fusion mechanism research - thermal resonance fusion mechanism results demonstrate how these light nuclei or atoms, such as deuterium, can be fused in the crystal of metal, such as Ni or alloy, with synthetic thermal vibrations and resonances at different modes and energies experimentally. The probability of tunnel effect at different resonance energy given by the WKB method is shown that indicates the thermal resonance fusion mode, especially combined with the tunnel effect, is possible and feasible. But the penetrating probability decreases very sharply when the input resonance energy decreases less than 3 keV, so for thermal resonance fusion, the key point is to increase the resonance peak or make the resonance sharp enough to the acceptable energy level by the suitable compound catalysts, and it is better to reach up more than 3 keV to make the penetrating probability larger than 10^{-10}.

  3. Light Steel Framing: Improving the Integral Design 

    E-Print Network [OSTI]

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

    2006-09-11

    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 ...

  4. Aspects of Electron-Phonon Self-Energy Revealed From Angle-Resolved...

    Office of Scientific and Technical Information (OSTI)

    ELEMENTARY PARTICLES AND FIELDS; PHOTOEMISSION; SELF-ENERGY; EMISSION SPECTROSCOPY; ELECTRONS; PHONONS Other,OTHER Word Cloud More Like This Full Text Journal Articles DOI:...

  5. Net electron-phonon scattering rates in InN/GaN multiple quantum...

    Office of Scientific and Technical Information (OSTI)

    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...

  6. 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)

    2012-05-15

    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.

  7. Solid state lighting component

    DOE Patents [OSTI]

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

    2010-10-26

    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.

  8. Solid state lighting component

    DOE Patents [OSTI]

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

    2012-07-10

    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.

  9. 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

    2013-09-10

    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.

  10. Validation of Phonon Physics in the CDMS Detector Monte Carlo

    SciTech Connect (OSTI)

    McCarthy, K.A.; Leman, S.W.; Anderson, A.J.; /MIT; Brandt, D.; /SLAC; Brink, P.L.; Cabrera, B.; Cherry, M.; /Stanford U.; Do Couto E Silva, E.; /SLAC; Cushman, P.; /Minnesota U.; Doughty, T.; /UC, Berkeley; Figueroa-Feliciano, E.; /MIT; Kim, P.; /SLAC; Mirabolfathi, N.; /UC, Berkeley; Novak, L.; /Stanford U.; Partridge, R.; /SLAC; Pyle, M.; /Stanford U.; Reisetter, A.; /Minnesota U. /St. Olaf Coll.; Resch, R.; /SLAC; Sadoulet, B.; Serfass, B.; Sundqvist, K.M.; /UC, Berkeley /Stanford U.

    2012-06-06

    The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.

  11. Effect of 13C isotope doping on the optical phonon modes in graphene: Localization and Raman spectroscopy

    E-Print Network [OSTI]

    Rodriguez-Nieva, J. F.

    The effect of [superscript 13]C isotope impurities on the phonon properties of graphene is discussed theoretically. We calculated the values of the phonon lifetimes due to isotope impurity scattering for all values of ...

  12. Changes in rotational characters of one- and two-phonon $?$-vibrational bands in $^{105}$Mo

    E-Print Network [OSTI]

    Masayuki Matsuzaki

    2014-12-19

    The $\\gamma$ vibration is the most typical low-lying collective motion prevailing the nuclear chart. But only few one-phonon rotational bands in odd-$A$ nuclei have been known. Furthermore, two-phonon states, even the band head, have been observed in a very limited number of nuclides not only of odd-$A$ but even-even. Among them, that in $^{105}$Mo is unique in that Coriolis effects are expected to be stronger than in $^{103}$Nb and $^{105}$Nb on which theoretical studies were reported. Then the purpose of the present work is to study $^{105}$Mo paying attention to rotational character change of the one-phonon and two-phonon bands. The particle-vibration coupling model based on the cranking model and the random-phase approximation is used to calculate the vibrational states in rotating odd-$A$ nuclei. The present model reproduces the observed yrast zero-phonon and one-phonon bands well. Emerging general features of the rotational character change from low spin to high spin are elucidated. In particular, the reason why the one-phonon band does not exhibit signature splitting is clarified. The calculated collectivity of the two-phonon states, however, is located higher than observed.

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

    E-Print Network [OSTI]

    Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations Denis L 2014) We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene that at temperature T specific heat varies with temperature as Tn , where n Ľ 1 for graphene, n Ľ 1

  14. Evidence of surface acoustic wave band gaps in the phononic crystals created on thin plates

    E-Print Network [OSTI]

    Deymier, Pierre

    Evidence of surface acoustic wave band gaps in the phononic crystals created on thin plates Xinya acoustic wave SAW band gaps. In this letter, we report a new type of phononic crystals manufactured Institute of Physics. DOI: 10.1063/1.2167794 The propagation of acoustic waves in periodic composite

  15. 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 ...

  16. Transmission and reflection of phonons and rotons at the superfluid helium-solid interface

    E-Print Network [OSTI]

    I. N. Adamenko; K. E. Nemchenko; I. V. Tanatarov

    2012-06-16

    We solve the problem of the transmission and reflection of phonons and rotons at the interface between superfluid helium and a solid, for all angles of incidence and in both directions. A consistent solution of the problem is presented which allows us to rigorously describe the simultaneous creation of phonons, $R^-$, and $R^+$ rotons in helium by either a phonon from the solid or a helium quasiparticle incident on the interface. The interaction of all $HeII$ quasiparticles with the interface, and their transmission, reflection and conversion into each other, is described in a unified way. The angles of propagation and the probabilities of creating quasiparticles are obtained for all cases. Andreev reflection of helium phonons and rotons is predicted. The energy flows through the interface due to phonons, $R^-$, and $R^+$ rotons are derived. The small contribution of the $R^-$ rotons is due to the small probability of an $R^-$ roton being created by a phonon in the solid, and vice versa. This explains the failure to directly create beams of $R^-$ rotons prior to the experiments of Tucker and Wyatt in 1999. New experiments for creating $R^-$ rotons, by beams of high-energy phonons (h-phonons), are suggested.

  17. Wave transmission, phonon localization, and heat conduction of a one-dimensional Frenkel-Kontorova chain

    E-Print Network [OSTI]

    Li, Baowen

    Wave transmission, phonon localization, and heat conduction of a one-dimensional Frenkel 7 August 1998; revised manuscript received 19 October 1998 We study the transmission coefficient the transmission coefficients for all eigenfrequen- cies. The phonon localization of the incommensurated FK chain

  18. Superconductivity-induced phonon anomalies in high-Tc superconductors: A Raman intensity study

    E-Print Network [OSTI]

    Sipe,J. E.

    Superconductivity-induced phonon anomalies in high-Tc superconductors: A Raman intensity study O. V of a number of Raman-active phonons below the superconducting transition temperature in YBa2Cu3O7 x , Bi2Sr2Ca to obtain information about the superconducting state.4 Several years ago, Friedl et al.5 ob- served

  19. Unified phonon-based approach to the thermodynamics of solid, liquid and gas states

    E-Print Network [OSTI]

    Dima Bolmatov; Dmitry Zavyalov; Mikhail Zhernenkov; Edvard T. Musaev; Yong Q. Cai

    2015-12-22

    We introduce a unified approach to states of matter (solid, liquid and gas) and describe the thermodynamics of the pressure-temperature phase diagram in terms of phonon excitations. We derive the effective Hamiltonian with low-energy cutoff in two transverse phonon polarizations (phononic band gaps) by breaking the symmetry in phonon interactions. Further, we construct the statistical mechanics of states of aggregation employing the Debye approximation. The introduced formalism covers the Debye theory of solids, the phonon theory of liquids, and thermodynamic limits such as the Dulong-Petit thermodynamic limit, the ideal gas limit and the new thermodynamic limit, dubbed here the Frenkel line thermodynamic limit. We discuss the phonon propagation and localization effects in liquids above and below the Frenkel line, and explain the "fast sound" phenomenon. As a test for our theory we calculate velocity-velocity autocorrelation and pair distribution functions within the Green-Kubo formalism. We show the consistency between dynamics of phonons and pair correlations in the framework of the unified approach. New directions towards advancements in phononic band gaps engineering, hypersound manipulation technologies and exploration of exotic behaviour of fluids relevant to geo- and planetary sciences are discussed. The presented results are equally important both for practical implications and for fundamental research.

  20. 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)

    2012-08-15

    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.

  1. 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

    2015-01-01

    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.

  2. 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)

    2014-10-28

    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.

  3. Phonons in two-dimensional soft colloidal crystals

    E-Print Network [OSTI]

    Ke Chen; Tim Still; Samuel Schoenholz; Kevin B. Aptowicz; Michael Schindler; A. C. Maggs; Andrea J. Liu; A. G. Yodh

    2013-09-11

    The vibrational modes of pristine and polycrystalline monolayer colloidal crystals composed of thermosensitive microgel particles are measured using video microscopy and covariance matrix analysis. At low frequencies, the Debye relation for two dimensional harmonic crystals is observed in both crystal types; at higher frequencies, evidence for van Hove singularities in the phonon density of states is significantly smeared out by experimental noise and measurement statistics. The effects of these errors are analyzed using numerical simulations. We introduce methods to correct for these limitations, which can be applied to disordered systems as well as crystalline ones, and we show that application of the error correction procedure to the experimental data leads to more pronounced van Hove singularities in the pristine crystal. Finally, quasi-localized low-frequency modes in polycrystalline two-dimensional colloidal crystals are identified and demonstrated to correlate with structural defects such as dislocations, suggesting that quasi-localized low-frequency phonon modes may be used to identify local regions vulnerable to rearrangements in crystalline as well as amorphous solids.

  4. 1 Copyright 2007 by ASME THE ROLE OF THERMAL EXCITATION OF D BAND ELECTRONS IN ULTRAFAST

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    1 Copyright © 2007 by ASME THE ROLE OF THERMAL EXCITATION OF D BAND ELECTRONS IN ULTRAFAST LASER://www.faculty.virginia.edu/CompMat/ ABSTRACT The temperature dependences of the electron heat capacity and electron-phonon coupling factor for noble (Cu) and transition (Pt) metals are investigated based on the electron density of states (DOS

  5. Single-phonon and multi-phonon excitations of the $?$ vibration in rotating odd-$A$ nuclei

    E-Print Network [OSTI]

    Masayuki Matsuzaki

    2014-10-20

    Multi-phonon excitations in atomic nuclei were observed very rarely although collective motions in quantum many-body systems are described as bosonic excitations. In particular, the first two-phonon $\\gamma$ vibrational ($2\\gamma$) excitation in odd-$A$ nuclei was reported in 2006 and only a few have been known. Quite recently, conspicuously enhanced $B(E2)$s feeding $2\\gamma$ states were observed in $^{105}$Nb and conjectured that their parent states are candidates of $3\\gamma$ states. In the present work, the model space is enlarged from the present author's previous calculation for $^{103}$Nb. The purpose is twofold: One is to see how the description of $2\\gamma$ states is improved, and the other is to examine the existence of collective $3\\gamma$ states, and when they exist, study their collectivity through calculating interband $B(E2)$s. The particle-vibration coupling model based on the cranking model and the random-phase approximation is used to calculate the vibrational states in rotating odd-$A$ nuclei. Interband $B(E2)$s are calculated by adopting the method of the generalized intensity relation. The present calculation reproduces the observed spectra of $0\\gamma$ - $2\\gamma$ states well and gives collective $3\\gamma$ states with enhanced $B(E2)$s to $2\\gamma$ states in $^{103}$Nb and $^{105}$Nb. The most collective $3\\gamma$ state with the highest $K$ at zero rotation is thought to be the main component of the observed band.

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

    E-Print Network [OSTI]

    Elliott, James

    polyethylene Sho Hida a , Takuma Hori a , Takuma Shiga a , James Elliott b , Junichiro Shiomi a,c, a Department dynamics study of heat conduction in carbon nanotube (CNT)/polyethylene (PE) composites. Particular across the CNT/polyethylene interfaces ($1 Â 10Ŕ7 m2 K WŔ1 ) and a moder- ate but non

  7. 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

  8. First-principles prediction of phononic thermal conductivity of silicene: A

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing(Journal Article) |production atmeasurement forces.comparison with graphene (Journal

  9. Nonlinear propagation and control of acoustic waves in phononic superlattices

    E-Print Network [OSTI]

    Jiménez, Noé; Picó, Rubén; García-Raffi, Lluís M; Sánchez-Morcillo, Víctor J

    2015-01-01

    The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band-gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media (where distortion can be cancelled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime.

  10. Odd-spin yrast states as multiple quadrupole-phonon excitations

    E-Print Network [OSTI]

    N. Pietralla; P. von Brentano; T. Otsuka; R. F. Casten

    1998-03-27

    The wavefunctions of the lowest odd spin positive parity yrast states in the IBA are shown to be nearly pure multiple quadrupole-phonon excitations even outside the three dynamical symmetries. The empirical data for collective nuclei with 30 < Z < 80 confirm these predictions. The quadrupole-phonon purity of the 2^+_1 state can be measured from E2-branching ratios of the 3^+_1 state. These data show a high correlation to the 2^+_1 Q-phonon purity deduced from the E2-decay of 2^+ states.

  11. Smart Lighting Controller!! Smart lighting!

    E-Print Network [OSTI]

    Anderson, Betty Lise

    'll build the circuit! We'll use an LED to represent the room lights! #12;4! Block diagram! Battery! Rail! #12;23! LED: light-emitting diode! Diode conducts current in only one direction! When current flows1! Smart Lighting Controller!! #12;2! Smart lighting! No need to spend energy lighting the room if

  12. 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

    2013-05-01

    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.

  13. Comprehensive phonon map offers direction for engineering new...

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

    so the best thermoelectric materials have low thermal conductivity (making them good heat insulators) but good electrical properties for delivering a voltage. One potential...

  14. 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

    2015-01-01

    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.

  15. Thermal engine

    SciTech Connect (OSTI)

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

    1984-01-03

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

  16. Electron-phonon coupling in a system with broken symmetry: Surface

    Office of Scientific and Technical Information (OSTI)

    Electron-phonon coupling in a system with broken symmetry: Surface ofBe(0001) Chien, TeYu; He, Xiaobo; Mo, Sung-Kwan;...

  17. Phonon anomalies and superconductivity in the Heusler compound YPd?Sn

    SciTech Connect (OSTI)

    Tütüncü, H. M. [Sakarya Üniversitesi, Fen-Edebiyat Fakültesi, Fizik Bölümü, 54187, Adapazar? (Turkey); Srivastava, G. P. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2014-07-07

    We have studied the structural and electronic properties of YPd?Sn in the Heusler structure using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. The electronic results indicate that the density of states at the Fermi level is primarily derived from Pd d states, which hybridize with Y d and Sn p states. Using our structural and electronic results, phonons and electron-phonon interactions have been studied by employing a linear response approach based on the density functional theory. Phonon anomalies have been observed for transverse acoustic branches along the [110] direction. This anomalous dispersion is merely a consequence of the strong coupling. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter is found to be ?=0.99. Using this value, the superconducting critical temperature is calculated to be 4.12 K, in good accordance with the recent experimental value of 4.7 K.

  18. Coupling of nitrogen vacancy centers in nanodiamonds by means of phonons

    E-Print Network [OSTI]

    Andreas Albrecht; Alex Retzker; Fedor Jelezko; Martin B. Plenio

    2013-07-11

    Realising controlled quantum dynamics via the magnetic interactions between colour centers in diamond remains a challenge despite recent demonstrations for nanometer separated pairs. Here we propose to use the intrinsic acoustical phonons in diamond as a data bus for accomplishing this task. We show that for nanodiamonds the electron-phonon coupling can take significant values that together with mode frequencies in the THz range, can serve as a resource for conditional gate operations. Based on these results we analyze how to use this phonon-induced interaction for constructing quantum gates among the electron-spin triplet ground states, introducing the phonon dependence via Raman transitions. Combined with decoupling pulses this offers the possibility for creating entangled states within nanodiamonds on the scale of several tens of nanometers, a promising prerequisite for quantum sensing applications.

  19. 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

  20. Lattice motions from THz phonon-polaritons measured with femtosecond x-ray diffraction

    SciTech Connect (OSTI)

    Schoenlein, Robert William; Cavalleri, A.; Wall, S.; Simpson, C.; Statz, E.; Ward, D.W.; Nelson, K.A.; Schoenlein, R.W.; Rini, M.; Dean, N.; Khalil, M.

    2006-08-07

    We use femtosecond x-ray diffraction to measure the coherent lattice displacements associated with the excitation and propagation of THz phonon polaritons in LiTaO3.

    1. Phonons and lattice dielectric properties of zirconia Xinyuan Zhao and David Vanderbilt

      E-Print Network [OSTI]

      Vanderbilt, David

      Phonons and lattice dielectric properties of zirconia Xinyuan Zhao and David Vanderbilt Department, 77.84.Bw I. INTRODUCTION ZrO2, or zirconia, has a wide range of materials applica- tions because

    2. 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)

      2014-09-15

      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.

    3. Quasi-two dimensional spin and phonon excitations in La1.965Ba0.035CuO4

      SciTech Connect (OSTI)

      Wagman, J.; Parshall, D.; Stone, Matthew B; Savici, Andrei T; Zhao, Yang; Dabkowska, H. A.; Gaulin, B. D.

      2015-01-01

      We present time-of-fight inelastic neutron scattering measurements of La1:965Ba0:035CuO4 (LBCO), a lightly doped member of the high temperature superconducting La-based cuprate family. By using time-of-flight neutron instrumentation coupled with single crystal sample rotation we obtain a four-dimensional data set (three Q and one energy) that is both comprehensive and spans a large region of reciprocal space. Our measurements identify rich structure in the energy dependence of the highly dispersive spin excitations, which are centered at equivalent ( 1/2 ; 1/2 ;L) wave-vectors. These structures correlate strongly with several crossings of the spin excitations with the lightly dispersive phonons found in this system. These eects are signicant and account for on the order of 25% of the total inelastic scattering for energies between 5 and 40meV at low jQj. Interestingly, this scattering also presents little or no L-dependence. As the phonons and dispersive spin excitations centred at equivalent ( 1/2 ; 1/2 ;L) wave-vectors are common to all members of La-based 214 copper oxides, we conclude such strong quasi-two dimensional scattering enhancements are likely to occur in all such 214 families of materials, including those concentrations corresponding to superconducting ground states. Such a phenomenon appears to be a fundamental characteristic of these materials and is potentially related to superconducting pairing.

    4. Local lattice distortions and thermal transport in perovskite manganites Department of Physics, University of Miami, Coral Gables, Florida 33124

      E-Print Network [OSTI]

      Local lattice distortions and thermal transport in perovskite manganites J. L. Cohn Department temperature and magnetic field are reported for perovskite manganites that exhibit ferromagnetic FM , charge- sistance CMR in the perovskite manganites involves electron-phonon interactions in addition to the double

    5. 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)

      2013-07-01

      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)

    6. Local formation of HArF in solid argon: Low-temperature limit and thermal activation

      E-Print Network [OSTI]

      Lignell, H.; Khriachtchev, L.; Lignell, A.; Räsänen, M.

      2010-01-01

      Räsänen, IR light. The thermal activation of the process wasand R. ?ArHAr? and thermal activation of these processes aretemperature limit and thermal activation H. Lignell, a? L.

    7. Novel Transparent Phosphor Conversion Matrix with High Thermal...

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

      Transparent Phosphor Conversion Matrix with High Thermal Conductivity for Next-Generation Phosphor-Converted LED-based Solid State Lighting Novel Transparent Phosphor Conversion...

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

      SciTech Connect (OSTI)

      Jo, Insun; Pettes, Michael; Lindsay, Lucas R; Ou, Eric; Weathers, Annie; Moore, Arden; Yao, Zhen; Shi, Li

      2015-01-01

      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.

    9. 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

    10. Chemical Agent Induced Reduction of Skin Light Scattering 

      E-Print Network [OSTI]

      Hirshburg, Jason M.

      2011-02-22

      Skin turbidity limits light based medical applications while increasing the risk of epidermal thermal injury. Collagen fibers are responsible for the majority of light scattering within skin. Chemicals, known as clearing ...

    11. Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

      SciTech Connect (OSTI)

      Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)

      1994-12-01

      Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

    12. Proposed Universal Relationships Describing Electron Phonon Mediated Superconductivity and Accommodation of the Cuprates and Pnictides

      E-Print Network [OSTI]

      D. A. Nepela

      2008-07-10

      A universal and self-consistent set of equations is developed utilizing the principle empirical parameters of Superconductivity which are the coherent condensation temperature, the Debye temperature, the coherent condensation energy gap at critical temperature equals zero degrees Kelvin and the electron phonon coupling constant. Empirical data from both crystalline elements and amorphous compounds is shown to produce the same self consistent relationships which are critical temperature equals Debye energy/2 exp(-2/electron phonon coupling constant), coherent condensation temperature equals the Debye energy exp (-2/electron phonon coupling constant) and the ratio of coherent condensation temperature/critical temperature equals 2.0 i.e. coherent condensation temperature equals coherent energy gap and is found to be constant for all superconductors. We also find that electron phonon coupling constant is related exponentially related to the zero point energy where the zero point energy equals the Debye energy/2 and is the zero point energy of a quantum mechanical oscillator. These relationships are derived exclusively from electron phonon mediated superconductor data and are also shown to encompass cuprate superconductors with ease. [Abridged

    13. Light Matters (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

      ScienceCinema (OSTI)

      Atwater, Harry (Director, Light-Material Interactions in Energy Conversion (LMI), California Institute of Technology); LMI Staff

      2011-11-02

      'Light Matters' was submitted by the Center for Light-Material Interactions in Energy Conversion (LMI) 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 its 'striking photography and visual impact'. LMI, an EFRC directed by Harry Atwater at the California Institute of Technology is a partnership of scientists from three institutions: CalTech (lead), University of California, Berkeley, and the University of Illinois at Urbana-Champaign. 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 Light-Material Interactions in Energy Conversion is 'to tailor the morphology, complex dielectric structure, and electronic properties of matter to sculpt the flow of sunlight, enabling light conversion to electrical and chemical energy with unprecedented efficiency.' Research topics are: catalysis (imines hydrocarbons), solar photovoltaic, solar fuels, photonic, solid state lighting, metamaterial, optics, phonons, thermal conductivity, solar electrodes, photsynthesis, CO{sub 2} (convert), greenhouse gas, and matter by design.

    14. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    15. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    16. Advanced Thermal Control

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

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

    17. 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.

      2013-03-05

      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.

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

      E-Print Network [OSTI]

      Zhao, Wei

      2014-07-08

      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...

    19. Phonons and specific heat of linear dense phases of atoms physisorbed in the grooves of carbon nanotube bundles

      E-Print Network [OSTI]

      Antonio Siber

      2002-12-24

      The vibrational properties (phonons) of a one-dimensional periodic phase of atoms physisorbed in the external groove of the carbon nanotube bundle are studied. Analytical expressions for the phonon dispersion relations are derived. The derived expressions are applied to Xe, Kr and Ar adsorbates. The specific heat pertaining to dense phases of these adsorbates is calculated.

    20. Cerenkov Light

      ScienceCinema (OSTI)

      Slifer, Karl

      2014-05-22

      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.

    1. Cerenkov Light

      SciTech Connect (OSTI)

      Slifer, Karl

      2013-06-13

      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.

    2. 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...

    3. A photonic transistor device based on photons and phonons in a cavity electromechanical system

      E-Print Network [OSTI]

      Cheng Jiang; Ka-Di Zhu

      2012-09-21

      We present a scheme for photonic transistors based on photons and phonons in a cavity electromechanical system, which is consisted of a superconducting microwave cavity coupled to a nanomechanical resonator. Control of the propagation of photons is achieved through the interaction of microwave field (photons) and nanomechanical vibrations (phonons). By calculating the transmission spectrum of the signal field, we show that the signal field can be efficiently attenuated or amplified, depending on the power of a second `gating'(pump) field. This scheme may be a promising candidate for single-photon transistors and pave the way for numerous applications in telecommunication and quantum information technologies.

    4. A photonic transistor device based on photons and phonons in a cavity electromechanical system

      E-Print Network [OSTI]

      Jiang, Cheng

      2012-01-01

      We present a scheme for photonic transistors based on photons and phonons in a cavity electromechanical system, which is consisted of a superconducting microwave cavity coupled to a nanomechanical resonator. Control of the propagation of photons is achieved through the interaction of microwave field (photons) and nanomechanical vibrations (phonons). By calculating the transmission spectrum of the signal field, we show that the signal field can be efficiently attenuated or amplified, depending on the power of a second `gating'(pump) field. This scheme may be a promising candidate for single-photon transistors and pave the way for numerous applications in telecommunication and quantum information technologies.

    5. 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)

      2011-02-15

      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.

    6. Electron thermal conductivity owing to collisions between degenerate electrons

      E-Print Network [OSTI]

      P. S. Shternin; D. G. Yakovlev

      2006-08-17

      We calculate the thermal conductivity of electrons produced by electron-electron Coulomb scattering in a strongly degenerate electron gas taking into account the Landau damping of transverse plasmons. The Landau damping strongly reduces this conductivity in the domain of ultrarelativistic electrons at temperatures below the electron plasma temperature. In the inner crust of a neutron star at temperatures T electron conductivity due to electron-ion (electron-phonon) scattering and becomes competitive with the the electron conductivity due to scattering of electrons by impurity ions.

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

      E-Print Network [OSTI]

      Paxton, Benjamin John

      2006-01-01

      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). ...

    8. 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

    9. EFFECT OF PHONON INTERACTIONS ON LIMITING THE f.Q PRODUCT OF MICROMECHANICAL RESONATORS

      E-Print Network [OSTI]

      Ayazi, Farrokh

      Energy stored Energy dissipated per cycle of oscillation . (1) For an acoustic wave propagating in solids, the sound abortion coefficient, )( , defined as [4] () = 1 2 Mean energy dissipated Energy flux in the wave by dissipation of energy from the acoustic wave. The response of the phonon system to the acoustic wave

    10. Supplementary information to "Phonons in two-dimensional soft colloidal crystals"

      E-Print Network [OSTI]

      Schindler, Michael

      Supplementary information to "Phonons in two-dimensional soft colloidal crystals" Ke Chen et al. S1. Characterization of colloidal crystals. Colloidal crystals are characterized by sample lattice structure. Figure S1 of low frequency modes obtained from pristine colloidal crystals exhibit features of plane waves

    11. Phonons in two-dimensional soft colloidal crystals Ke Chen,1, 2

      E-Print Network [OSTI]

      Schindler, Michael

      Phonons in two-dimensional soft colloidal crystals Ke Chen,1, 2 Tim Still,1 Samuel Schoenholz,1 and polycrystalline monolayer colloidal crystals composed of thermosensitive microgel particles are measured using-frequency modes in polycrystalline two-dimensional colloidal crystals are identified and demonstrated to correlate

    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)

      2001-01-01

      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.

      1999-06-22

      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. 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)

      1999-01-01

      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.

    15. In-situ optical transmission electron microscope study of exciton phonon replicas in ZnO nanowires by cathodoluminescence

      SciTech Connect (OSTI)

      Yang, Shize; Tian, Xuezeng; Wang, Lifen; Wei, Jiake; Qi, Kuo; Li, Xiaomin; Xu, Zhi E-mail: xdbai@iphy.ac.cn Wang, Wenlong; Zhao, Jimin; Bai, Xuedong E-mail: xdbai@iphy.ac.cn; Wang, Enge E-mail: xdbai@iphy.ac.cn

      2014-08-18

      The cathodoluminescence spectrum of single zinc oxide (ZnO) nanowires is measured by in-situ optical Transmission Electron Microscope. The coupling between exciton and longitudinal optical phonon is studied. The band edge emission varies for different excitation spots. This effect is attributed to the exciton propagation along the c axis of the nanowire. Contrary to free exciton emission, the phonon replicas are well confined in ZnO nanowire. They travel along the c axis and emit at the end surface. Bending strain increases the relative intensity of second order phonon replicas when excitons travel along the c-axis.

    16. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    17. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    18. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    19. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    20. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    1. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    2. Lighting in the Library

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

      by your library lights E Kilowatt-hours consumed by your library lights F Annual cost of operating your library lights H Current lighting index for your library ...

    3. 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

      1996-04-28

      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.

    4. Light's Darkness

      ScienceCinema (OSTI)

      Padgett, Miles [University of Glasgow, Glasgow, Scotland

      2010-01-08

      Optical vortices and orbital angular momentum are currently topical subjects in the optics literature. Although seemingly esoteric, they are, in fact, the generic state of light and arise whenever three or more plane waves interfere. To be observed by eye the light must be monochromatic. Laser speckle is one such example, where the optical energy circulates around each black spot, giving a local orbital angular momentum. This talk with report three on-going studies. First, when considering a volume of interfering waves, the laser specs map out threads of complete darkness embedded in the light. Do these threads form loops? Links? Or even knots? Second, when looking through a rapidly spinning window, the image of the world on the other side is rotated: true or false? Finally, the entanglement of orbital angular momentum states means measuring how the angular position of one photons sets the angular momentum of another: is this an angular version of the EPR (Einstein, Podolsky, and Rosen) paradox?

    5. Phonon-energy-coupling enhancement: Strengthening the chemical bonds of the SiO2/Si system

      E-Print Network [OSTI]

      Chen, Zhi

      Phonon-energy-coupling enhancement: Strengthening the chemical bonds of the SiO2/Si system Zhi Chena and Jun Guo Department of Electrical and Computer Engineering and Center for Nanoscale Science

    6. Energy relaxation during hot-exciton transport in quantum wells: Direct observation by spatially resolved phonon-sideband spectroscopy

      E-Print Network [OSTI]

      Zhao, Hui; Moehl, Sebastian; Kalt, Heinz

      2002-10-01

      We investigate the energy relaxation of excitons during the real-space transport in ZnSe quantum wells by using microphotoluminescence with spatial resolution enhanced by a solid immersion lens. The spatial evolution of the LO-phonon sideband...

    7. 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

      2014-01-01

      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.

    8. Types of Lights Types of Lights

      E-Print Network [OSTI]

      1 Types of Lights Types of Lights q So far we have studied point lights ­ Radiate in all direc7ons q Other lights ­ Direc7onal lights (posi7on-independent) ­ Spotlights #12;2 Direc1onal Lights q Shine in a single, uniform direc7on q All rays

    9. Linear Boltzmann equation as the long time dynamics of an electron weakly coupled to a phonon field

      E-Print Network [OSTI]

      Laszlo Erdos

      2001-08-29

      We consider the long time evolution of a quantum particle weakly interacting with a phonon field. We show that in the weak coupling limit the Wigner distribution of the electron density matrix converges to the solution of the linear Boltzmann equation globally in time. The collision kernel is identified as the sum of an emission and an absorption term that depend on the equilibrium distribution of the free phonon modes.

    10. Thermal Transport in Nanoporous Materials for Energy Applications

      E-Print Network [OSTI]

      Fang, Jin

      2012-01-01

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

    11. Unusual Enhancement in Intrinsic Thermal Conductivity of Multilayer Graphene by Tensile Strains

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

      Kuang, Youdi; Lindsay, Lucas R.; Huang, Baoling

      2015-01-01

      High basal plane thermal conductivity k of multi-layer graphene makes it promising for thermal management applications. Here we examine the effects of tensile strain on thermal transport in this system. Using a first principles Boltzmann-Peierls equation for phonon transport approach, we calculate the room-temperature in-plane lattice k of multi-layer graphene (up to four layers) and graphite under different isotropic tensile strains. The calculated in-plane k of graphite, finite mono-layer graphene and 3-layer graphene agree well with previous experiments. The dimensional transitions of the intrinsic k and the extent of the diffusive transport regime from mono-layer graphene to graphite are presented.more »We find a peak enhancement of intrinsic k for multi-layer graphene and graphite with increasing strain and the largest enhancement amplitude is about 40%. In contrast the calculated intrinsic k with tensile strain decreases for diamond and diverges for graphene, we show that the competition between the decreased mode heat capacities and the increased lifetimes of flexural phonons with increasing strain contribute to this k behavior. Similar k behavior is observed for 2-layer hexagonal boron nitride systems, suggesting that it is an inherent thermal transport property in multi-layer systems assembled of purely two dimensional atomic layers. This study provides insights into engineering k of multi-layer graphene and boron nitride by strain and into the nature of thermal transport in quasi-two-dimensional and highly anisotropic systems.« less

    12. Unusual Enhancement in Intrinsic Thermal Conductivity of Multilayer Graphene by Tensile Strains

      SciTech Connect (OSTI)

      Kuang, Youdi [Hong Kong Univ. of Science and Technology (Hong Kong); Lindsay, Lucas R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Huang, Baoling [Hong Kong Univ. of Science and Technology (Hong Kong)

      2015-01-01

      High basal plane thermal conductivity k of multi-layer graphene makes it promising for thermal management applications. Here we examine the effects of tensile strain on thermal transport in this system. Using a first principles Boltzmann-Peierls equation for phonon transport approach, we calculate the room-temperature in-plane lattice k of multi-layer graphene (up to four layers) and graphite under different isotropic tensile strains. The calculated in-plane k of graphite, finite mono-layer graphene and 3-layer graphene agree well with previous experiments. The dimensional transitions of the intrinsic k and the extent of the diffusive transport regime from mono-layer graphene to graphite are presented. We find a peak enhancement of intrinsic k for multi-layer graphene and graphite with increasing strain and the largest enhancement amplitude is about 40%. In contrast the calculated intrinsic k with tensile strain decreases for diamond and diverges for graphene, we show that the competition between the decreased mode heat capacities and the increased lifetimes of flexural phonons with increasing strain contribute to this k behavior. Similar k behavior is observed for 2-layer hexagonal boron nitride systems, suggesting that it is an inherent thermal transport property in multi-layer systems assembled of purely two dimensional atomic layers. This study provides insights into engineering k of multi-layer graphene and boron nitride by strain and into the nature of thermal transport in quasi-two-dimensional and highly anisotropic systems.

    13. Light Computing

      E-Print Network [OSTI]

      Gordon Chalmers

      2006-10-13

      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.

    14. Extremely Low-Loss Acoustic Phonons in a Quartz Bulk Acoustic Wave Resonator at Millikelvin Temperature

      E-Print Network [OSTI]

      Maxim Goryachev; Daniel L. Creedon; Eugene N. Ivanov; Serge Galliou; Roger Bourquin; Michael E. Tobar

      2012-04-02

      Low-loss, high frequency acoustic resonators cooled to millikelvin temperatures are a topic of great interest for application to hybrid quantum systems. When cooled to 20 mK, we show that resonant acoustic phonon modes in a Bulk Acoustic Wave (BAW) quartz resonator demonstrate exceptionally low loss (with $Q$-factors of order billions) at frequencies of 15.6 and 65.4 MHz, with a maximum $f.Q$ product of 7.8$\\times10^{16}$ Hz. Given this result, we show that the $Q$-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained. Such resonators possess the low losses crucial for electromagnetic cooling to the phonon ground state, and the possibility of long coherence and interaction times of a few seconds, allowing multiple quantum gate operations.

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

      E-Print Network [OSTI]

      Süsstrunk, Roman

      2015-01-01

      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.

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

      E-Print Network [OSTI]

      D. G. Yakovlev; A. D. Kaminker

      1996-04-19

      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.

    17. Holographic thermalization of charged operators

      E-Print Network [OSTI]

      Alejandro Giordano; Nicolas E. Grandi; Guillermo A. Silva

      2014-12-26

      We study a light-like charged collapsing shell in AdS-Reissner-Nordstrom spacetime, investigating whether the corresponding Vaidya metric is supported by matter that satisfies the null energy condition. We find that, if the absolute value of the charge decreases during the collapse, energy conditions are fulfilled everywhere in spacetime. On the other hand, if the absolute value of the charge increases, the metric does not satisfy energy conditions in the IR region. Therefore, from the gauge/gravity perspective, this last case is only useful to study the thermalization of the UV degrees of freedom. For all these geometries, we probe the thermalization process with two point correlators of charged operators, finding that the thermalization time grows with the charge of the operator, as well as with the dimension of space.

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

      SciTech Connect (OSTI)

      Ring, P.; Litvinova, E.; Tselyaev, V.

      2012-10-20

      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.

    19. 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

      2015-06-17

      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. In addition, 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 themore »FK model 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

    20. 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

      2015-01-01

      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...

    1. The feasibility of thermal and compositional convection in Earth’s inner core

      E-Print Network [OSTI]

      Lythgoe, Karen H.; Rudge, John F.; Neufeld, Jerome A.; Deuss, Arwen

      2015-03-12

      of a large core thermal conductivity result in stable thermal stratification, hindering convection. However, an unstable density stratification may arise due to the pressure dependant partition coefficient of certain light elements. We show...

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

      SciTech Connect (OSTI)

      Zhou, Fei; Nielson, Weston; Xia, Yi; Ozoli?š, Vidvuds

      2014-10-01

      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.

    3. Spin and phonon anomalies in epitaxial self-assembled CoFe{sub 2}O{sub 4}-BaTiO{sub 3} multiferroic nanostructures

      SciTech Connect (OSTI)

      Tsai, C. Y.; Chen, H. R.; Hsieh, W. F., E-mail: wfhsieh@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 300, Taiwan (China); Cheng, H. M.; Tsai, L. N. [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Huang, K. F.; Lai, C. H. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 31013, Taiwan (China); Chu, Y. H. [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 31040, Taiwan (China)

      2014-06-23

      Temperature dependent magnetic and phonon anomalies in epitaxial self-assembled CoFe{sub 2}O{sub 4} (CFO) rods embedded in BaTiO{sub 3} (BTO) matrix nanostructures were investigated. The temperature dependence of A{sub 1}(2TO) phonon frequency of BTO indicates that the BTO matrix experiences structural transformations. The lattice strain produced during the structural transformations drives spin reorientation in CFO rods, resulting in anomalous changes of magnetization. Through correlating the phonon anomalies with the increase of in-plane spin ordering, we show the spin-phonon coupling induces the softening of A{sub 1g} and A{sub 1}(2TO) phonons. It suggests that spin strongly couples with lattice strain and phonons in this nanostructure.

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

      SciTech Connect (OSTI)

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

      2015-01-01

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

    5. 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)

      2014-08-28

      {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.

    6. Enhancing the thermoelectric figure of merit through the reduction of bipolar thermal conductivity with heterostructure barriers

      SciTech Connect (OSTI)

      Bahk, Je-Hyeong, E-mail: jbahk@purdue.edu; Shakouri, Ali [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)

      2014-08-04

      In this paper, we present theoretically that the thermoelectric figure of merit for a semiconductor material with a small band gap can be significantly enhanced near the intrinsic doping regime at high temperatures via the suppression of bipolar thermal conductivity when the minority carriers are selectively blocked by heterostructure barriers. This scheme is particularly effective in nanostructured materials where the lattice thermal conductivity is lowered by increased phonon scatterings at the boundaries, so that the electronic thermal conductivity including the bipolar term is limiting the figure of merit zT. We show that zT can be enhanced to above 3 for p-type PbTe, and above 2 for n-type PbTe at 900?K with minority carrier blocking, when the lattice thermal conductivity is as low as 0.3?W/m K.

    7. Thermal transport properties of metal/MoS{sub 2} interfaces from first principles

      SciTech Connect (OSTI)

      Mao, Rui; Kong, Byoung Don; Kim, Ki Wook, E-mail: kwk@ncsu.edu [Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695-7911 (United States)

      2014-07-21

      Thermal transport properties at the metal/MoS{sub 2} interfaces are analyzed by using an atomistic phonon transport model based on the Landauer formalism and first-principles calculations. The considered structures include chemisorbed Sc(0001)/MoS{sub 2} and Ru(0001)/MoS{sub 2}, physisorbed Au(111)/MoS{sub 2}, as well as Pd(111)/MoS{sub 2} with intermediate characteristics. Calculated results illustrate a distinctive dependence of thermal transfer on the details of interfacial microstructures. More specifically, the chemisorbed case with a stronger bonding exhibits a generally smaller interfacial thermal resistance than the physisorbed. Comparison between metal/MoS{sub 2} and metal/graphene systems suggests that metal/MoS{sub 2} is significantly more resistive. Further examination of lattice dynamics identifies the presence of multiple distinct atomic planes and bonding patterns at the interface as the key origins of the observed large thermal resistance.

    8. 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)

      2001-01-01

      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.

    9. Taunton Municipal Lighting Plant- Residential and Non-Profit Weatherization Program

      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...

    10. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMassR&D100Nationalquestionnaires 0 Averagequestionnaires 7tniLighting Sign In

    11. 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.

    12. A green-yellow emitting oxyfluoride solid solution phosphor Sr[subscript 2]Ba(AlO[subscript 4]F)[subscript 1;#8722;x](SiO[subscript 5])x:Ce[superscript 3+] for thermally stable, high color rendition solid state white lighting

      SciTech Connect (OSTI)

      Denault, Kristin A.; George, Nathan C.; Paden, Sara R.; Brinkley, Stuart; Mikhailovsky, Alexander A.; Neuefeind, Jörg; DenBaars, Steven P.; Seshadri, Ram (UCSB); (ORNL)

      2012-10-23

      A near-UV excited, oxyfluoride phosphor solid solution Sr{sub 1.975}Ce{sub 0.025}Ba(AlO{sub 4}F){sub 1-x}(SiO{sub 5}){sub x} has been developed for solid state white lighting applications. An examination of the host lattice, and the local structure around the Ce{sup 3+} activator ions through a combination of density functional theory, synchrotron X-ray and neutron powder diffraction and total scattering, and electron paramagnetic resonance, points to how chemical substitutions play a crucial role in tuning the optical properties of the phosphor. The maximum emission wavelength can be tuned from green ({lambda}{sub em} = 523 nm) to yellow ({lambda}{sub em} = 552 nm) by tuning the composition, x. Photoluminescent quantum yield is determined to be 70 {+-} 5% for some of the examples in the series. Excellent thermal properties were found for the x = 0.5 sample, with the photoluminescence intensity at 160 C only decreased to 82% of its room temperature value. Phosphor-converted LED devices fabricated using an InGaN LED ({lambda}{sub max} = 400 nm) exhibit high color rendering white light with R{sub a} = 70 and a correlated color temperature near 7000 K. The value of R{sub a} could be raised to 90 by the addition of a red component, and the correlated color temperature lowered to near 4000 K.

    13. Light-control of the ultrafast demagnetization pathway in an antiferromagnetic insulator

      E-Print Network [OSTI]

      Sala, Vera G; Miller, Timothy A; Viola, Daniele; Luppi, Elenora; Véniard, Valérie; Cerullo, Giulio; Wall, Simon

      2015-01-01

      Ultrafast demagnetization is a complex process involving strong coupling between electronic, spin, and structural degrees of freedom which is dependent on the type of magnetic order and band structure. Controlling these interactions is key for developing magnetic devices that can fully exploit femto-magnetism. Here we show that energy and polarization tunable femtosecond light pulses can be used to control the demagnetization pathway in the antiferromagnetic insulator Cr2O3. We visualize how the demagnetization dynamics depends on the pump photon energy using transient second harmonic spectroscopy. This enables us to monitor changes to the magnetic and crystalline symmetry, revealing the key role played by phonons in the demagnetization process. The phonon symmetry can be selected through the colour and polarization of the pump pulse, providing control over the demagnetization process, which could lead to faster and more efficient control of magnetic order.

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

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

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

    15. Effects of thermal fluctuations on thermal inflation

      E-Print Network [OSTI]

      Takashi Hiramatsu; Yuhei Miyamoto; Jun'ichi Yokoyama

      2014-12-25

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

    16. 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)

      2002-03-05

      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.

    17. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    18. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    19. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    20. Alliant Energy Interstate Power and Light (Electric) - Residential...

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

      70% of total installation cost up to 250 Room Air Conditioners: 20 SolidThermal Entry Door: 10 - 25 LED and CFL bulbs: 50% of cost Summary Interstate Power and Light...

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

      SciTech Connect (OSTI)

      Zhou, X.J.

      2010-04-30

      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

    2. Sandia Energy - (Lighting and) Solid-State Lighting: Science...

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

      (Lighting and) Solid-State Lighting: Science, Technology, Economic Perspectives Home Energy Research EFRCs Solid-State Lighting Science EFRC (Lighting and) Solid-State Lighting:...

    3. 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....

    4. DNA Engine Thermal Cycler

      E-Print Network [OSTI]

      Raizada, Manish N.

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

    5. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    6. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    7. One-phonon isovector 2(1,MS)(+) state in neutron-rich nucleus (132)Te

      SciTech Connect (OSTI)

      Danchev, M. [University of Tennessee, Knoxville (UTK); Rainovski, G. [Bulgarian Academy of Sciences, Sofia, Bulgaria; Gladnishki, K. A. [Bulgarian Academy of Sciences, Sofia, Bulgaria; Pietralla, N. [Technische Universitat Darmstadt, Germany; Ponomarev, V. Yu [Technische Universitat Darmstadt, Germany; Scheck, M. [Technische Universitat Darmstadt, Germany; Wambach, J. [Technische Universitat Darmstadt, Germany; Pietralla, N. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Gargano, A. [University of Naples Frederico Secundo, Italy; Covello, A. [University of Naples Frederico Secundo, Italy; Baktash, Cyrus [ORNL; Beene, James R [ORNL; Galindo-Uribarri, Alfredo {nmn} [ORNL; Gross, Carl J [ORNL; Radford, David C [ORNL; Yu, Chang-Hong [ORNL; Bingham, C. R. [University of Tennessee, Knoxville (UTK); Riedinger, L. L. [University of Tennessee, Knoxville (UTK); Stuchbery, Andrew E [ORNL; Zamfir, Nicolae Victor [ORNL

      2011-01-01

      The 2{sub 2}{sup +} state in {sup 132}Te is identified as the one-phonon mixed-symmetry state in a projectile Coulomb excitation experiment presenting a firm example of a mixed-symmetry state in unstable, neutron-rich nuclei. The results of shell-model calculations based on the low-momentum interaction V{sub low-k} are in good agreement with experiment demonstrating the ability of the effective shell-model interaction to produce states of mixed-symmetry character.

    8. Coherent acoustic phonon generation in GaAs{sub 1?x}Bi{sub x}

      SciTech Connect (OSTI)

      Joshya, R. S.; Kini, R. N., E-mail: rajeevkini@iisertvm.ac.in [Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), CET Campus, Thiruvananthapuram, Kerala 695016 (India); Ptak, A. J.; France, R.; Mascarenhas, A. [National Renewable Energy Laboratory (NREL), 1617 Cole Blvd., Golden, Colorado 80401 (United States)

      2014-03-03

      We have used femtosecond laser pulses to generate coherent acoustic phonons in the dilute Bismide alloy, GaAs{sub 1?x}Bi{sub x}. The observed oscillation periods match well with the oscillation periods calculated using the propagating strain pulse model. We attribute the generation process predominantly to electronic stress due to the absorption of the laser pulse at the surface of the GaAs{sub 1?x}Bi{sub x} layer. Our initial estimates suggest that the incorporation of Bi in GaAs causes an enhancement of the hydrostatic deformation potential because of the resonant state in the valence band due to isolated Bi impurities.

    9. Influence of Complex Exciton-Phonon Coupling on Optical Absorption and Energy Transfer of Quantum Aggregates

      E-Print Network [OSTI]

      Jan Roden; Alexander Eisfeld; Wolfgang Wolff; Walter T. Strunz

      2009-11-04

      We present a theory that efficiently describes the quantum dynamics of an electronic excitation that is coupled to a continuous, highly structured phonon environment. Based on a stochastic approach to non-Markovian open quantum systems, we develop a dynamical framework that allows us to handle realistic systems where a fully quantum treatment is desired yet the usual approximation schemes fail. The capability of the method is demonstrated by calculating spectra and energy transfer dynamics of mesoscopic molecular aggregates, elucidating the transition from fully coherent to incoherent transfer.

    10. 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)

      2014-04-24

      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.

    11. Raman spectroscopy of graphite in high magnetic fields: Electron-phonon coupling and magnetophonon resonance

      SciTech Connect (OSTI)

      Kim, Younghee; Smirnov, Dmitry; Kalugin, Nikolai G.; Lombardo, Antonio; Ferrari, Andrea C.

      2013-12-04

      The magneto-Raman measurements of graphite were performed in a back-scattering Faraday geometry at temperature 10 K in magnetic fields up to 45 T. The experimental data reveal the rich structure of Raman-active excitations dominated by K-point massive electrons. At high magnetic fields the graphite E{sub 2g} Raman line shows complex multi- component behavior interpreted as magnetophonon resonance coupled electron-phonon modes at graphite’s K-point. Also we found the clear signature of the fundamental, strongly dumped, n=0 magnetophonon resonance associated with H point massless holes.

    12. 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

    13. 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

    14. Phonon and magnon scattering of Bi{sub 2}Fe{sub 4}O{sub 9} ceramic

      SciTech Connect (OSTI)

      Sharma, Poorva E-mail: vdinesh33@rediffmail.com; Kumar, Ashwini E-mail: vdinesh33@rediffmail.com; Varshney, Dinesh E-mail: vdinesh33@rediffmail.com

      2014-04-24

      We report the phonon structure of Bi{sub 2}Fe{sub 4}O{sub 9} ceramics as synthesized by solid-state reaction route. Rietveld refined X-ray diffraction patterns confirmed the formation of single-phase perovskite structure and all the peaks of Bi{sub 2}Fe{sub 4}O{sub 9} perfectly indexed to the orthorhombic (space group Pbam). Raman scattering measurements identifies 12A{sub g}+1B{sub 2g}+1B{sub 3g} Raman active optical phonon modes. Apart from phonon scattering, mode at 470 cm{sup ?1} is observed which is due to magnon scattering. The P-E loop infers paraelectric nature of Bi{sub 2}Fe{sub 4}O{sub 9}.

    15. 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)

      2014-09-15

      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.

    16. 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.; Sankaranarayanan, S. K. R. S.

      2014-06-23

      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.

    17. 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)

      2007-05-22

      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.

    18. Controls for Solid-State Lighting

      SciTech Connect (OSTI)

      Rubinstein, Francis

      2007-06-22

      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.

    19. Evidence for a Surface-Phonon Contribution to Thin-Film Superconductivity - Depression of Tc by Noble-Gas Overlayers 

      E-Print Network [OSTI]

      Naugle, Donald G.; BAKER, JW; Allen, Roland E.

      1973-01-01

      by the frequency dependence of the product of the electron- phonon coupling constant and the phonon density of states, n2(&u)E(cu). Differences between the tran- sition temperatures of thin films and that of the bulk metal are often explained in terms of a modi.... III. RESULTS As indicated in Fig. 2 the noble-gas overlayers depress the transition temperature of thin Sn, Al, and Tl films. Associated with this decrease in T, was a small increase in the residual resistance. The fractional change in residual...

    20. 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)

      2014-03-31

      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.

    1. Evaluation of Metal Halide, Plasma, and LED Lighting Technologies for a Hydrogen Fuel Cell Mobile Light (H 2 LT)

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

      Miller, L. B.; Donohoe, S. P.; Jones, M. H.; White, W. A.; Klebanoff, L. E.; Velinsky, S. A.

      2015-04-22

      This article reports on the testing and comparison of a prototype hydrogen fuel cell light tower (H2LT) and a conventional diesel-powered metal halide light trailer for use in road maintenance and construction activities. The prototype was originally outfitted with plasma lights and then with light-emitting diode (LED) luminaires. Light output and distribution, lighting energy efficiency (i.e., efficacy), power source thermal efficiency, and fuel costs are compared. The metal halide luminaires have 2.2 and 3.1 times more light output than the plasma and LED luminaires, respectively, but they require more power/lumen to provide that output. The LED luminaires have 1.6 timesmore »better light efficacy than either the metal halide or plasma luminaires. The light uniformity ratios produced by the plasma and LED towers are acceptable. The fuel cell thermal efficiency at the power required to operate the plasma lights is 48%, significantly higher than the diesel generator efficiency of 23% when operating the metal halide lights. Due to the increased efficiency of the fuel cell and the LED lighting, the fuel cost per lumen-hour of the H2LT is 62% of the metal halide diesel light tower assuming a kilogram of hydrogen is twice the cost of a gallon of diesel fuel.« less

    2. 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.

      2015-02-01

      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

    3. 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)

      2012-06-04

      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.

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

      SciTech Connect (OSTI)

      Zhang, Yong Xie, Zhong-Xiang Yu, Xia; Wang, Hai-Bin; Li, Ke-Min

      2014-10-14

      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.

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

      SciTech Connect (OSTI)

      Lindsay, Lucas R; Broido, David; Carrete, Jesus; Mingo, Natalio; Reinecke, Tom

      2015-01-01

      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.

    6. Thermal properties of the optically transparent pore-free nanostructured yttria-stabilized zirconia

      SciTech Connect (OSTI)

      Ghosh, S.; Teweldebrhan, D.; Morales, J. R.; Garay, J. E.; Balandin, A. A.

      2009-12-01

      The authors report results of investigation of thermal conductivity of nanocrystalline yttria-stabilized zirconia. The optically transparent pore-free bulk samples were prepared via the spark plasma sintering process to ensure homogeneity. Thermal conductivity K was measured by two different techniques. It was found that the pore-free nanostructured bulk zirconia is an excellent thermal insulator with the room-temperature Kapprox1.7-2.0 W/m K. It was also shown that the 'phonon-hopping' model can accurately describe specifics of K dependence on temperature and the grain size. The obtained results are important for optimization of zirconia properties for specific applications in advanced electronics and coatings.

    7. Thermal Regimes of Northeast Streams

      E-Print Network [OSTI]

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

    8. Thermal hydraulics development for CASL

      SciTech Connect (OSTI)

      Lowrie, Robert B

      2010-12-07

      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.

    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)

      2014-06-14

      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?Ĺ, coordination number 12) compared to Sr{sup 2+} (?1.44?Ĺ, 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. Lighting Options for Homes.

      SciTech Connect (OSTI)

      Baker, W.S.

      1991-04-01

      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)

    11. Laser-induced light emission from carbon nanoparticles

      SciTech Connect (OSTI)

      Osswald, S.; Behler, K.; Gogotsi, Y.

      2008-10-01

      Strong absorption of light in a broad wavelength range and poor thermal conductance between particles of carbon nanomaterials, such as nanotubes, onions, nanodiamond, and carbon black, lead to strong thermal emission (blackbody radiation) upon laser excitation, even at a very low (milliwatts) power. The lasers commonly used during Raman spectroscopy characterization of carbon can cause sample heating to very high temperatures. While conventional thermometry is difficult in the case of nanomaterials, Raman spectral features, such as the G band of graphitic carbon and thermal emission spectra were used to estimate the temperature during light emission that led to extensive graphitization and evaporation of carbon nanomaterials, indicating local temperatures exceeding 3500 deg. C.

    12. 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

      2013-05-14

      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.

    13. 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

      2006-10-30

      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.

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

      DOE Patents [OSTI]

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

      1995-01-01

      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.

    15. Cosmological moduli problem in large volume scenario and thermal inflation

      SciTech Connect (OSTI)

      Choi, Kiwoon [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Park, Wan-Il [School of Physics, KIAS, Seoul 130-722 (Korea, Republic of); Shin, Chang Sub, E-mail: kchoi@kaist.ac.kr, E-mail: wipark@kias.re.kr, E-mail: csshin@apctp.org [APCTP, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

      2013-03-01

      We show that in a large volume scenario of type IIB string or F-theory compactifications, single thermal inflation provides only a partial solution to the cosmological problem of the light volume modulus. We then clarify the conditions for double thermal inflation, being a simple extension of the usual single thermal inflation scenario, to solve the cosmological moduli problem in the case of relatively light moduli masses. Using a specific example, we demonstrate that double thermal inflation can be realized in large volume scenario in a natural manner, and the problem of the light volume modulus can be solved for the whole relevant mass range. We also find that right amount of baryon asymmetry and dark matter can be obtained via a late-time Affleck-Dine mechanism and the decays of the visible sector NLSP to flatino LSP.

    16. Solar Thermal Demonstration Project

      SciTech Connect (OSTI)

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

      2012-01-30

      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?ť 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.

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

      E-Print Network [OSTI]

      Deymier, Pierre

      2013-01-01

      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

    18. First-Principles Calculations on the Effect of Doping and Biaxial Tensile Strain on Electron-Phonon Coupling in Graphene

      E-Print Network [OSTI]

      Simons, Jack

      -Phonon Coupling in Graphene Chen Si,1,2 Zheng Liu,2 Wenhui Duan,1 and Feng Liu2,* 1 Department of Physics, Utah 84112, USA (Received 13 June 2013; published 6 November 2013) Graphene has exhibited a wealth of fascinating properties, but is also known not to be a superconductor. Remarkably, we show that graphene can

    19. Linear Boltzmann equation as the long time dynamics of an electron weakly coupled to a phonon eld

      E-Print Network [OSTI]

      Linear Boltzmann equation as the long time dynamics of an electron weakly coupled to a phonon #12 that in the weak coupling limit the Wigner distribution of the electron density matrix converges to the solution of the linear Boltzmann equation globally in time. The collision kernel is identi#12;ed as the sum

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

      DOE Patents [OSTI]

      Siminovitch, M.J.

      1992-11-10

      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.

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

      DOE Patents [OSTI]

      Siminovitch, Michael J. (Richmond, CA)

      1992-01-01

      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.

    2. 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)

      2010-03-16

      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.

    3. Radiative cooling of bulk silicon by incoherent light pump

      SciTech Connect (OSTI)

      Malyutenko, V. K. Bogatyrenko, V. V.; Malyutenko, O. Yu.

      2013-12-23

      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.

    4. Effects of system-bath entanglement on the performance of light-harvesting systems: A quantum heat engine perspective

      E-Print Network [OSTI]

      Xu, Dazhi; Zhao, Yang; Cao, Jianshu

      2015-01-01

      We explore energy transfer in a generic three-level system, which is coupled to three non-equilibrium baths. Built on the concept of quantum heat engine, our three-level model describes non-equilibrium quantum processes including light-harvesting energy transfer, nano-scale heat transfer, photo-induced isomerization, and photovoltaics in double quantum-dots. In the context of light-harvesting, the excitation energy is first pumped up by sunlight, then is transferred via two excited states which are coupled to a phonon bath, and finally decays to the ground state. The efficiency of this process is evaluated by steady state analysis via a polaron-transformed master equation; thus a wide range of the system-phonon coupling strength can be covered. We show that the coupling with the phonon bath not only modifies the steady state, resulting in population inversion, but also introduces a finite steady state coherence which optimizes the energy transfer flux and efficiency. In the strong coupling limit, the steady s...

    5. Effects of system-bath entanglement on the performance of light-harvesting systems: A quantum heat engine perspective

      E-Print Network [OSTI]

      Dazhi Xu; Chen Wang; Yang Zhao; Jianshu Cao

      2015-08-19

      We explore energy transfer in a generic three-level system, which is coupled to three non-equilibrium baths. Built on the concept of quantum heat engine, our three-level model describes non-equilibrium quantum processes including light-harvesting energy transfer, nano-scale heat transfer, photo-induced isomerization, and photovoltaics in double quantum-dots. In the context of light-harvesting, the excitation energy is first pumped up by sunlight, then is transferred via two excited states which are coupled to a phonon bath, and finally decays to the ground state. The efficiency of this process is evaluated by steady state analysis via a polaron-transformed master equation; thus a wide range of the system-phonon coupling strength can be covered. We show that the coupling with the phonon bath not only modifies the steady state, resulting in population inversion, but also introduces a finite steady state coherence which optimizes the energy transfer flux and efficiency. In the strong coupling limit, the steady state coherence disappears and the efficiency approaches the heat engine limit given by Scovil and Schultz-Dubois in Phys. Rew. Lett. 2, 262 (1959).

    6. 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

      2015-01-06

      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.

    7. Practical image based lighting 

      E-Print Network [OSTI]

      Lee, Jaemin

      2003-01-01

      information is lighting. Image based lighting that is developed to recover illumination information of the real world from photographs has recently been popular in computer graphics. In this thesis we present a practical image based lighting method. Our...

    8. Light in the city

      E-Print Network [OSTI]

      Srinivasan, Kavita, 1976-

      2002-01-01

      This thesis focuses on enhancing the awareness of light for the pedestrian,and using light as a way of revealing the structure of the city and its relation to the cosmos. It proposes that aesthetic qualities of light inform ...

    9. Advances in Lighting 

      E-Print Network [OSTI]

      Tumber, A. J.

      1981-01-01

      Increasing electricity costs have made a significant impact on lighting. The Illuminating Engineering society (I.E.S.) and the lighting industry are producing new standards, procedures and products to make lighting more appropriate and energy...

    10. Natural lighting and skylights 

      E-Print Network [OSTI]

      Evans, Benjamin Hampton

      1961-01-01

      There are many physiological and psychological factors which enter into the proper design of space for human occupancy. One of these elements is light. Both natural light and manufactured light are basic tools with which any designer must work...

    11. Specific light in sculpture

      E-Print Network [OSTI]

      Powell, John William

      1989-01-01

      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 ...

    12. 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

    13. HEATS: Thermal Energy Storage

      SciTech Connect (OSTI)

      2012-01-01

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

    14. 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...

    15. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      are also under consideration. Outside the DOE, the Environmental Protection Agency's Green Lights program promotes energy-efficient lighting as a means to reducing...

    16. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      Motivation and Computation of Lighting Measures Floorspace by Lighting Equipment Configuration As described in Appendix A, for each building b, the CBECS data set has the total...

    17. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      more comprehensive understanding of commercial lighting and the potential for lighting energy savings. Steps to build on this analysis can be taken in many directions. One...

    18. Leavenworth Tree Lighting

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

      Join HERO for our annual Leavenworth Tree Lighting Ceremony & Shopping SATURDAY DECEMBER 12, 2015 Leavenworth Christmas Lighting Festival Visitors return year after year for some...

    19. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      light by passing electricity through mercury vapor, which causes the fluorescent coating to glow or fluoresce. High-Efficiency Ballast (HEB): A lighting conservation feature...

    20. 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.

    1. Intrinsic phonon decoherence and quantum gates in coupled lateral quantum dot charge qubits

      E-Print Network [OSTI]

      Markus J. Storcz; Udo Hartmann; Sigmund Kohler; Frank K. Wilhelm

      2005-07-28

      Recent experiments by Hayashi et al. [Phys. Rev. Lett. 91, 226804 (2003)] demonstrate coherent oscillations of a charge quantum bit (qubit) in laterally defined quantum dots. We study the intrinsic electron-phonon decoherence and gate performance for the next step: a system of two coupled charge qubits. The effective decoherence model contains properties of local as well as collective decoherence. Decoherence channels can be classified by their multipole moments, which leads to different low-energy spectra. It is shown that due to the super-Ohmic spectrum, the gate quality is limited by the single-qubit Hadamard gates. It can be significantly improved, by using double-dots with weak tunnel coupling.

    2. Optimal Phonon-to-Spin Mapping in a system of a trapped ion

      E-Print Network [OSTI]

      Matthias M. Müller; Ulrich G. Poschinger; Tommaso Calarco; Simone Montangero; Ferdinand Schmidt-Kaler

      2015-04-11

      We propose a protocol for measurement of the phonon number distribution of a harmonic oscillator based on selective mapping to a discrete spin-1/2 degree of freedom. We consider a system of a harmonically trapped ion, where a transition between two long lived states can be driven with resolved motional sidebands. The required unitary transforms are generated by amplitude-modulated polychromatic radiation fields, where the time-domain ramps are obtained from numerical optimization by application of the Chopped RAndom Basis (CRAB) algorithm. We provide a detailed analysis of the scaling behavior of the attainable fidelities and required times for the mapping transform with respect to the size of the Hilbert space. As one application we show how the mapping can be employed as a building block for experiments which require measurement of the work distribution of a quantum process.

    3. Including the Effects of Electronic Excitations and Electron-Phonon Coupling in Cascade Simulations

      SciTech Connect (OSTI)

      Duffy, Dorothy |

      2008-07-01

      Radiation damage has traditionally been modeled using cascade simulations however such simulations generally neglect the effects of electron-ion interactions, which may be significant in high energy cascades. A model has been developed which includes the effects of electronic stopping and electron-phonon coupling in Molecular Dynamics simulations by means of an inhomogeneous Langevin thermostat. The energy lost by the atoms to electronic excitations is gained by the electronic system and the energy evolution of the electronic system is modeled by the heat diffusion equation. Energy is exchanged between the electronic system and the atoms in the Molecular Dynamics simulation by means of a Langevin thermostat, the temperature of which is the local electronic temperature. The model is applied to a 10 keV cascade simulation for Fe. (authors)

    4. 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

      2015-02-27

      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

    5. The hydrogen bond network of water supports propagating optical phonon-like modes

      E-Print Network [OSTI]

      Daniel C. Elton; M. -V. Fernández-Serra

      2015-11-03

      The local structure of liquid water as a function of temperature is a source of intense research. This structure is intimately linked to the dynamics of water molecules, which can be measured using Raman and infrared spectroscopies. The assignment of spectral peaks depends on whether they are collective modes or single molecule motions. Vibrational modes in liquids are usually considered to be associated to the motions of single molecules or small clusters. Using molecular dynamics simulations we find dispersive optical phonon-like modes in the librational and OH stretching bands. We argue that on subpicosecond time scales these modes propagate through water's hydrogen bond network over distances of up to two nanometers. In the long wavelength limit these optical modes exhibit longitudinal-transverse splitting, indicating the presence of coherent long range dipole-dipole interactions, as in ice. Our results indicate the dynamics of liquid water have more similarities to ice than previously thought.

    6. Wave transmission, phonon localization and heat conduction of 1D Frenkel-Kontorova chain

      E-Print Network [OSTI]

      Peiqing Tong; Baowen Li; Bambi Hu

      1999-01-20

      We study the transmission coefficient of a plane wave through a 1D finite quasi-periodic system -- the Frenkel-Kontorova (FK) model -- embedding in an infinite uniform harmonic chain. By varying the mass of atoms in the infinite uniform chain, we obtain the transmission coefficients for {\\it all} eigenfrequencies. The phonon localization of the incommensurated FK chain is also studied in terms of the transmission coefficients and the Thouless exponents. Moreover, the heat conduction of Rubin-Greer-like model for FK chain at low temperature is calculated. It is found that the stationary heat flux $J(N)\\sim N^{\\alpha}$, and $\\alpha$ depends on the strength of the external potential.

    7. Metamaterials as Photonic or Phononic crystals: towards molding the flow of waves on subwavelength scales

      E-Print Network [OSTI]

      Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy

      2011-01-01

      In this letter we show that it is possible to merge the properties of metamaterials and photonic/phononic crystals. To do so, we demonstrate experimentally a defect cavity in a material made of resonant electric wires arranged on a lattice much smaller than the free space wavelength. We prove that such a cavity, analogous to those designed in photonic crystals, can present very high quality factors. Furthermore, we establish that the resonant state displays a mode volume much smaller than a wavelength cube, owing to the subwavelength nature of the unit cell. We also underline that this type of structure is not sensible to positional disorder. Our approach paves the way towards the manipulation of waves at scales independents of the wavelength.

    8. Observation of a phononic Mollow triplet in a hybrid spin-nanomechanical system

      E-Print Network [OSTI]

      Benjamin Pigeau; Sven Rohr; Laure Mercier de Lépinay; Arnaud Gloppe; Vincent Jacques; Olivier Arcizet

      2015-02-25

      Reminiscent of the bound character of a qubit's dynamics confined on the Bloch sphere, the observation of a Mollow triplet in the resonantly driven qubit fluorescence spectrum represents one of the founding signatures of Quantum Electrodynamics. Here we report on its observation in a hybrid spin-nanomechanical system, where a Nitro-gen Vacancy spin qubit is magnetically coupled to the vibrations of a Silicon Carbide nanowire. A resonant microwave field turns the originally parametric hybrid interac-tion into a resonant process, where acoustic phonons are now able to induce transitions between the dressed qubit states, leading to synchronized spin-oscillator dynamics. We further explore the vectorial character of the hybrid coupling to the bidimensional de-formations of the nanowire. The demonstrated microwave assisted synchronization of the spin-oscillator dynamics opens novel perspectives for the exploration of spin-dependent forces, the key-ingredient for quantum state transfer.

    9. Thermal and Electrical Transport in Oxide Heterostructures

      E-Print Network [OSTI]

      Ravichandran, Jayakanth

      2011-01-01

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

    10. Spin-phonon coupling in Gd(Co{sub 1/2}Mn{sub 1/2})O{sub 3} perovskite

      SciTech Connect (OSTI)

      Silva, R. X.; Reichlova, H.; Marti, X.; Barbosa, D. A. B.; Lufaso, M. W.; Araujo, B. S.; Ayala, A. P.; and others

      2013-11-21

      We have investigated the temperature-dependent Raman-active phonons and the magnetic properties of Gd(Co{sub 1/2}Mn{sub 1/2})O{sub 3} perovskite ceramics in the temperature range from 40?K to 300?K. The samples crystallized in an orthorhombic distorted simple perovskite, whose symmetry belongs to the Pnma space group. The data reveal spin-phonon coupling near the ferromagnetic transition occurring at around 120?K. The correlation of the Raman and magnetization data suggests that the structural order influences the magnitude of the spin-phonon coupling.

    11. Thermal emission in the ultrastrong coupling regime

      E-Print Network [OSTI]

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

      2012-10-08

      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.

    12. Thermal Energy Storage

      SciTech Connect (OSTI)

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

      2013-06-05

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

    13. Lighting Controls | Department of Energy

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

      Controls Lighting Controls Use lighting controls to automatically turn lights on and off as needed, and save energy. | Photo courtesy of iStockphoto.comMaliketh. Use lighting...

    14. Characterization of the KID-Based Light Detectors of CALDER

      E-Print Network [OSTI]

      Casali, N; Cardani, L; Castellano, M G; Colantoni, I; Coppolecchia, A; Cosmelli, C; Cruciani, A; D'Addabbo, A; Di Dominio, S; Martinez, M; Tomei, C; Vignati, M

      2015-01-01

      The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of $5\\times5$ cm$^2$ and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio...

    15. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    16. 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

    17. Thermal neutron detection system

      DOE Patents [OSTI]

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

      2000-01-01

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

    18. Thermal Performance Benchmarking (Presentation)

      SciTech Connect (OSTI)

      Moreno, G.

      2014-11-01

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

    19. Pedestrian Friendly Outdoor Lighting

      SciTech Connect (OSTI)

      Miller, N. J.; Koltai, R. N.; McGowan, T. K.

      2013-12-01

      The GATEWAY program followed two pedestrian-scale lighting projects that required multiple mockups – one at Stanford University in California and the other at Chautauqua Institution in upstate New York. The report provides insight into pedestrian lighting criteria, how they differ from street and area lighting criteria, and how solid-state lighting can be better applied in pedestrian applications.

    20. Semiconductor superlattice diodes for detection of terahertz photons: The role of hybridization of the plasma and polar-optical phonon modes

      SciTech Connect (OSTI)

      Ignatov, Anatoly A., E-mail: ign@ipm.sci-nnov.ru [Institute for Physics of Microstructures, RAS, GSP-105, Nizhny Novgorod 603950 (Russian Federation); Department of Radio-Physics, University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation)

      2014-08-28

      The current (voltage) responsivity of a superlattice-based diode detector has been studied theoretically in the terahertz frequency band that includes the region of the polar-optical phonon frequencies. Within the framework of an equivalent circuit approach, the electro-dynamical model which allows one to analyze the responsivity taking into account the hybridization of the plasma and polar-optical phonon modes both in the substrate and in the cladding layers of the diode has been suggested. It has been shown that the presence of the plasma and polar-optical phonon modes gives rise to strong features in the frequency dependence of the responsivity, i.e., to the resonance dips and peaks at frequencies of hybridized plasmons and polar-optical phonons. It has been suggested that by judicious engineering of the superlattice-based diodes, it would be possible to enhance substantially their responsivity in the terahertz frequency band.

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

      E-Print Network [OSTI]

      D. A. Baiko; D. G. Yakovlev

      1996-04-28

      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.

    2. 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)

      2010-12-15

      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)

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

      SciTech Connect (OSTI)

      Hopkins, Patrick E.

      2011-10-01

      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.

    4. 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

      2003-01-01

      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...

    5. Tips: Lighting | Department of Energy

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

      Tips: Lighting Tips: Lighting Lighting choices save you money. Energy-efficient light bulbs are available in a wide variety of sizes and shapes. Lighting choices save you money....

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

      E-Print Network [OSTI]

      Royal, Emily

      2012-05-31

      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...

    7. 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

    8. CONNECTED LIGHTING SYSTEMS MEETING

      Office of Energy Efficiency and Renewable Energy (EERE)

      There is a lot of buzz today about the Internet of Things and the convergence of intelligent controllable light sources, communication networks, sensors, and data exchange in future lighting...

    9. Fast Light, Fast Neutrinos?

      E-Print Network [OSTI]

      Kevin Cahill

      2011-10-10

      In certain media, light has been observed with group velocities faster than the speed of light. The recent OPERA report of superluminal 17 GeV neutrinos may describe a similar phenomenon.

    10. Kyler Nelson Light Timer

      E-Print Network [OSTI]

      Kachroo, Pushkin

      designated by the user, the Arduino board will dim the light to save energy. The user designates the time instance, the light is dimmed using pulse width modulation (PWM) in the Arduino's pin number 11

    11. Automatic lighting controls demonstration

      SciTech Connect (OSTI)

      Rubinstein, F.; Verderber, R.

      1990-03-01

      The purpose of this work was to demonstrate, in a real building situation, the energy and peak demand reduction capabilities of an electronically ballasted lighting control system that can utilize all types of control strategies to efficiently manage lighting. The project has demonstrated that a state-of-the-art electronically ballasted dimmable lighting system can reduce energy and lighting demand by as least 50% using various combinations of control strategies. By reducing light levels over circulation areas (tuning) and reducing after hours light levels to accommodate the less stringent lighting demands of the cleaning crew (scheduling), lighting energy consumption on weekdays was reduced an average of 54% relative to the initial condition. 10 refs., 14 figs., 3 tabs.

    12. AQUIFER THERMAL ENERGY STORAGE

      E-Print Network [OSTI]

      Tsang, C.-F.

      2011-01-01

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

    13. Scattering Solar Thermal Concentrators

      Office of Environmental Management (EM)

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

    14. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    15. Solar Thermal Powered Evaporators

      E-Print Network [OSTI]

      Moe, Christian Robert

      2015-01-01

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

    16. Lighting and Daylight Harvesting 

      E-Print Network [OSTI]

      Bos, J.

      2011-01-01

      in 1992 to serve the lighting design needs of the architectural and interior design communities. With over fifty years of combined experience, our areas of expertise range from architectural and theatrical lighting to custom fixture design. Bos... Lighting Design We are active members of the International Association of Lighting Designers, the American Institute of Architects, the Illuminating Engineering Society, International Dark Skies Association and the United States Green Building Council...

    17. LED Lighting Retrofit 

      E-Print Network [OSTI]

      Shaw-Meadow, N.

      2011-01-01

      kWh is the one that never gets used? ?Dedicated to making environmentally responsible products? Ringdale Introduction LED Roadway Lighting Better Light, Fewer Watts. Period. Nathan Shaw-Meadow LED Lighting Specialist Ringdale ActiveLED ESL.../exponential efficiency growth often deters investment today 7 Challenges to Implementation ESL-KT-11-11-57 CATEE 2011, Dallas, Texas, Nov. 7 ? 9, 2011 ? Municipal Street Light Case Study 8 ? Replaced 400W High Pressure Sodium fixtures with 52W Active...

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

      DOE Patents [OSTI]

      Thompson, Mark E.; Dapkus, P. Daniel

      2014-07-22

      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.

    19. And the Oscar for Sustainable Mobile Lighting Goes to.... Lighting...

      Energy Savers [EERE]

      And the Oscar for Sustainable Mobile Lighting Goes to.... Lighting Up Operations with Hydrogen and Fuel Cell Technology And the Oscar for Sustainable Mobile Lighting Goes to.......

    20. Fast Thermal Simulation for Architecture Level Dynamic Thermal Management

      E-Print Network [OSTI]

      Tan, Sheldon X.-D.

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

    1. Detecting coherent phonon wave effects in superlattices using time-domain thermoreflectance

      E-Print Network [OSTI]

      Luckyanova, Maria N. (Maria Nickolayevna)

      2012-01-01

      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 ...

    2. Light sterile neutrinos in the early universe

      SciTech Connect (OSTI)

      Lunardini, Cecilia [Department of Physics, Arizona State University, Tempe, Arizona 85287-1404 (United States)

      2014-06-24

      Cosmological and terrestrial data suggests the number of light neutrinos may be greater than 3, motivating a careful reexamination of cosmological bounds on extra light species. Big bang nucleosynthesis constrains the number of relativistic neutrino species present during nucleosynthesis, N{sub eff}{sup BBN}, while measurements of the cosmic microwave background (CMB) angular power spectrum constrain the effective energy density in relativistic neutrinos at the time of matter-radiation equality, N{sub eff}{sup CMB}. We review a scenario with two sterile neutrinos and explore whether partial thermalization of the sterile states can ease the tension between cosmological constraints on N{sub eff}{sup BBN} and terrestrial data. We conclude that, still, two additional light sterile neutrinos species cannot fit all the data at the 95% confidence level.

    3. Evaluation of Metal Halide, Plasma, and LED Lighting Technologies for a Hydrogen Fuel Cell Mobile Light (H 2 LT)

      SciTech Connect (OSTI)

      Miller, L. B.; Donohoe, S. P.; Jones, M. H.; White, W. A.; Klebanoff, L. E.; Velinsky, S. A.

      2015-04-22

      This article reports on the testing and comparison of a prototype hydrogen fuel cell light tower (H2LT) and a conventional diesel-powered metal halide light trailer for use in road maintenance and construction activities. The prototype was originally outfitted with plasma lights and then with light-emitting diode (LED) luminaires. Light output and distribution, lighting energy efficiency (i.e., efficacy), power source thermal efficiency, and fuel costs are compared. The metal halide luminaires have 2.2 and 3.1 times more light output than the plasma and LED luminaires, respectively, but they require more power/lumen to provide that output. The LED luminaires have 1.6 times better light efficacy than either the metal halide or plasma luminaires. The light uniformity ratios produced by the plasma and LED towers are acceptable. The fuel cell thermal efficiency at the power required to operate the plasma lights is 48%, significantly higher than the diesel generator efficiency of 23% when operating the metal halide lights. Due to the increased efficiency of the fuel cell and the LED lighting, the fuel cost per lumen-hour of the H2LT is 62% of the metal halide diesel light tower assuming a kilogram of hydrogen is twice the cost of a gallon of diesel fuel.

    4. 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)

      2014-05-15

      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.

    5. Thermal protection apparatus

      DOE Patents [OSTI]

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

      1984-03-20

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

    6. Thermal protection apparatus

      DOE Patents [OSTI]

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

      1985-01-01

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

    7. Thermal radiation Ron Zevenhoven

      E-Print Network [OSTI]

      Zevenhoven, Ron

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

    8. Mechanical Engineering & Thermal Group

      E-Print Network [OSTI]

      Mojzsis, Stephen J.

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

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

      SciTech Connect (OSTI)

      Clark, J.S.

      1991-01-01

      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.

    10. Lighting Design | Department of Energy

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

      Design Lighting Design Energy-efficient indoor and outdoor lighting design focuses on ways to improve both the quality and efficiency of lighting. | Photo courtesy of...

    11. Thermal treatment wall

      DOE Patents [OSTI]

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

      2000-01-01

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

    12. Tunable thermal link

      DOE Patents [OSTI]

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

      2014-07-15

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

    13. Solar thermal aircraft

      DOE Patents [OSTI]

      Bennett, Charles L. (Livermore, CA)

      2007-09-18

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

    14. 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

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

      E-Print Network [OSTI]

      Hardin, Corey Lee

      2011-01-01

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

    16. Induction Lighting: An Old Lighting Technology Made New Again

      Broader source: Energy.gov [DOE]

      Induction lighting is one of the best kept secrets in energy-efficient lighting. Simply stated, induction lighting is essentially a fluorescent light without electrodes or filaments, the items that...

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

      E-Print Network [OSTI]

      Bartovics, William A

      1984-01-01

      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 ...

    18. 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 ...

    19. Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

      E-Print Network [OSTI]

      Jaramillo, Rafael

      Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, ...

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

      SciTech Connect (OSTI)

      Guidotti, Ronald Armand

      2006-06-01

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

    1. 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.

      2014-05-01

      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.

    2. Lighting the Night: Technology, Urban Life and the Evolution of Street Lighting [Light in Place

      E-Print Network [OSTI]

      Holden, Alfred

      1992-01-01

      Electrical 16. "Highway Lighting by So­ dium Vapor Lamps,"Possibilities of Street: Lighting Improve­ ments," TheLaunches Broad Street Lighting Promotion Campaign," The

    3. ECE 466: LED Lighting Systems -Incandescent lightings rise and

      E-Print Network [OSTI]

      Connors, Daniel A.

      ECE 466: LED Lighting Systems - Incandescent lightings rise and demise via government policy - Alternative Fluorescent light sources and compact fluorescent lights (CFL) to incandescents - Alternative LED light sources - Color index as well as Watts to Lumens efficiency available from all three light sources

    4. 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

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

      SciTech Connect (OSTI)

      Narumanchi, S.

      2013-07-01

      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.

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

      SciTech Connect (OSTI)

      Narumanchi, S.

      2013-07-01

      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.

    7. Thermal Giant Gravitons

      E-Print Network [OSTI]

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

      2012-01-01

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

    8. Sandia Energy - Light Creation Materials

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

      Light Creation Materials Home Energy Research EFRCs Solid-State Lighting Science EFRC Overview Light Creation Materials Light Creation MaterialsAlyssa Christy2015-03-26T16:28:52+00...

    9. 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

    10. Phonon-roton modes of liquid 4He beyond the roton in MCM-41

      SciTech Connect (OSTI)

      Azuah, Richard T NIST Center for Neutron Research , Gaithersburg, MD; Omar Diallo, Souleymane ORNL; Adams, Mark A. ISIS Facility, Rutherford Appleton Laboratory; Kirichek, Oleg ISIS Facility, Rutherford Appleton Laboratory; Glyde, Henry R University of Delaware

      2013-01-01

      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.

    11. Multilayer thermal barrier coating systems

      DOE Patents [OSTI]

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

      2000-01-01

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

    12. Optical device with low electrical and thermal resistance bragg reflectors

      DOE Patents [OSTI]

      Lear, Kevin L. (Albuquerque, NM)

      1996-01-01

      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.

    13. National Synchrotron Light Source

      ScienceCinema (OSTI)

      BNL

      2009-09-01

      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.

    14. Visible Light Digital Camera --Up to 2.3MP resolution with LED lamps provides sharp images

      E-Print Network [OSTI]

      Short, Daniel

      · Visible Light Digital Camera -- Up to 2.3MP resolution with LED lamps provides sharp images regardless of lighting conditions · Fusion Picture in Picture (PIP) -- Displays thermal image super case FLIR i40 Additional Features · 0.6MP Visible Light Camera resolution · Picture in Picture (PIP

    15. Faster Than Light?

      E-Print Network [OSTI]

      Robert Geroch

      2010-05-10

      It is argued that special relativity remains a viable physical theory even when there is permitted signals traveling faster than light.

    16. Comparing Light Bulbs

      Office of Energy Efficiency and Renewable Energy (EERE)

      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.

    17. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      Illuminance Assignments for CBECS Building Activity Categories Illuminance ranges were adopted from the 1987 Illuminating Engineering Society (IES) Lighting Handbook. The IES...

    18. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      from the engineering literature, based on CBECS building activity.) 4. Efficacy: an energy efficiency measure. Technically, the amount of light produced per unit of energy...

    19. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      (CEC), March 1990. Advanced Lighting Technologies Application Guidelines (ALTAG), Building and Appliance Efficiency Office. 3. Dubin, F.S., Mindell, H.L., and Bloome, S., 1976....

    20. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      energy are presented in this section. Statistics are presented by subgroups based on building characteristics, and by subgroups based on lighting equipment. The three sets of...

    1. 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

    2. 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.

      2014-02-21

      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.

    3. 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

      2005-12-22

      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.

    4. Thermally Polymerized Rylene Nanoparticles

      E-Print Network [OSTI]

      Andrew, Trisha Lionel

      Rylene dyes functionalized with varying numbers of phenyl trifluorovinyl ether (TFVE) moieties were subjected to a thermal emulsion polymerization to yield shape-persistent, water-soluble chromophore nanoparticles. Perylene ...

    5. Thermal Insulation Systems 

      E-Print Network [OSTI]

      Stanley, T. F.

      1982-01-01

      Thermal insulation systems are receiving a high degree of attention in view of increasing energy cost. Industrial, commercial and residential energy users are all well aware of energy cost increases and great emphasis is being directed to energy...

    6. Photovoltaic-thermal collectors

      DOE Patents [OSTI]

      Cox, III, Charles H. (Carlisle, MA)

      1984-04-24

      A photovoltaic-thermal solar cell including a semiconductor body having antireflective top and bottom surfaces and coated on each said surface with a patterned electrode covering less than 10% of the surface area. A thermal-absorbing surface is spaced apart from the bottom surface of the semiconductor and a heat-exchange fluid is passed between the bottom surface and the heat-absorbing surface.

    7. Micro-Raman study on the softening and stiffening of phonons in rutile titanium dioxide film: Competing effects of structural defects, crystallite size, and lattice strain

      SciTech Connect (OSTI)

      Gautam, Subodh K.; Singh, Fouran, E-mail: fouran@gmail.com; Sulania, I.; Kulriya, P. K. [Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Singh, R. G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Pippel, E. [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

      2014-04-14

      Softening and stiffening of phonons in rutile titanium dioxide films are investigated by in situ micro-Raman studies during energetic ion irradiation. The in situ study minimized other possible mechanisms of phonon dynamics. Initial softening and broadening of Raman shift are attributed to the phonon confinement by structural defects and loss of stoichiometry. The stiffening of A{sub 1g} mode is ascribed to large distortion of TiO{sub 6} octahedra under the influence of lattice strain in the (110) plane, which gives rise to lengthening of equatorial Ti-O bond and shortening of apical Ti-O bond. The shortening of apical Ti-O bond induces stiffening of A{sub 1g} mode in the framework of the bond-order-length-strength correlation mechanism.

    8. Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress

      E-Print Network [OSTI]

      Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress Anthony J. Bellantuono1 thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant) maintained

    9. 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)

      2014-08-18

      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.

    10. Characterization and modeling of thermal diffusion and aggregation in nanofluids.

      SciTech Connect (OSTI)

      Gharagozloo, Patricia E.; Goodson, Kenneth E.

      2010-05-01

      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.

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

      E-Print Network [OSTI]

      Afshari, Ehsan

      on silicon carbide substrates and by chemical vapor deposition on nickel substrates. In the first few hundred lifetime in carbon nanotubes via time- resolved Raman anti-Stokes spectroscopy was performed by Song et al-SiC wafers by thermal decomposition epitaxial growth9 and also by chemical vapor deposition CVD on nickel.10

    12. 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

      2013-01-30

      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.

    13. Explosively pumped laser light

      DOE Patents [OSTI]

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

      1991-01-01

      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.

    14. Light intensity compressor

      DOE Patents [OSTI]

      Rushford, Michael C. (Livermore, CA)

      1990-01-01

      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.

    15. 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: swarthc@ufs.ac.za; Kumar, Vinod; Kumar, Vijay; Terblans, J. J.; Swart, H. C. E-mail: swarthc@ufs.ac.za; Kunti, A. K.; Dutta, S.; Chowdhury, M.; Sharma, S. K.

      2014-05-21

      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.

    16. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      Ballast: See High-Efficiency Ballast. Btu: British thermal unit. A unit quantity of energy consumed by or delivered to a building. A Btu is defined as the amount of energy...

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

      DOE Patents [OSTI]

      Benson, D.K.; Potter, T.F.

      1995-12-26

      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.

    18. Thermal Lens Spectroscopy Mladen Franko

      E-Print Network [OSTI]

      Reid, Scott A.

      Thermal Lens Spectroscopy Mladen Franko Laboratory of Environmental Research, University of Nova-beam Instruments 5 3.3 Differential Thermal Lens Instruments 7 3.4 Multiwavelength and Tunable Thermal Lens Spectrometers 8 3.5 Circular Dichroism TLS Instruments 9 3.6 Miniaturization of Thermal Lens Instruments 9 4

    19. 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

    20. VIRTUAL LIGHT: DIGITALLY-GENERATED LIGHTING FOR VIDEO CONFERENCING APPLICATIONS

      E-Print Network [OSTI]

      Greenberg, Albert

      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

    1. LightBox -Exploring Interaction Modalities with Colored Light

      E-Print Network [OSTI]

      of light to very subtle animations, transitions and dimmed lighting effects. Implementation LightBox is housed in an aluminum suitcase measuring 48x38x25cm. The lid of the suitcase contains a panel of 12x12 Design. Figure 1. An animated lighting sequence visualized on the hi-power LEDs of LightBox #12

    2. Indoor positioning algorithm using light-emitting diode visible light

      E-Print Network [OSTI]

      Kavehrad, Mohsen

      Indoor positioning algorithm using light- emitting diode visible light communications Zhou Zhou of Use: http://spiedl.org/terms #12;Indoor positioning algorithm using light-emitting diode visible light. This paper proposes a novel indoor positioning algorithm using visible light communications (VLC

    3. Pressure dependence of harmonic and an harmonic lattice dynamics in MgO: A ?rst-principles calculation and implications for lattice thermal conductivity

      SciTech Connect (OSTI)

      Tang, Xiaoli [Physics Department, Auburn University, Auburn, Alabama (United States); Dong, Jianjun [Physics Department, Auburn University, Auburn, Alabama (United States)

      2009-05-01

      We report a recent first-principles calculation of harmonic and anharmonic lattice dynamics of MgO. The 2nd order harmonic and 3rd order anharmonic interatomic interaction terms are computed explicitly, and their pressure dependences are discussed. The phonon mode Grueneisen parameters derived based on our calculated 3rd order lattice anharmonicity are in good agreement with those estimated using the finite difference method. The implications for lattice thermal conductivity at high pressure are discussed based on a simple kinetic transport theory.

    4. Article for thermal energy storage

      DOE Patents [OSTI]

      Salyer, Ival O. (Dayton, OH)

      2000-06-27

      A thermal energy storage composition is provided which is in the form of a gel. The composition includes a phase change material and silica particles, where the phase change material may comprise a linear alkyl hydrocarbon, water/urea, or water. The thermal energy storage composition has a high thermal conductivity, high thermal energy storage, and may be used in a variety of applications such as in thermal shipping containers and gel packs.

    5. 1D-to-3D transition of phonon heat conduction in polyethylene using molecular dynamics simulations

      E-Print Network [OSTI]

      Henry, Asegun

      The thermal conductivity of nanostructures generally decreases with decreasing size because of classical size effects. The axial thermal conductivity of polymer chain lattices, however, can exhibit the opposite trend, ...

    6. Effect of wettability on light oil steamflooding

      SciTech Connect (OSTI)

      Olsen, D.K.

      1991-12-01

      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.

    7. Effect of wettability on light oil steamflooding

      SciTech Connect (OSTI)

      Olsen, D.K.

      1991-12-01

      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.

    8. Tensile-property characterization of thermally aged cast stainless steels

      SciTech Connect (OSTI)

      Michaud, W.F.; Toben, P.T.; Soppet, W.K.; Chopra, O.K.

      1994-02-01

      The effect of thermal aging on tensile properties of cast stainless steels during service in light water reactors has been evaluated. Tensile data for several experimental and commercial heats of cast stainless steels are presented. Thermal aging increases the tensile strength of these steels. The high-C Mo-bearing CF-8M steels are more susceptible to thermal aging than the Mo-free CF-3 or CF-8 steels. A procedure and correlations are presented for predicting the change in tensile flow and yield stresses and engineering stress-vs.-strain curve of cast stainless steel as a function of time and temperature of service. The tensile properties of aged cast stainless steel are estimated from known material information, i.e., chemical composition and the initial tensile strength of the steel. The correlations described in this report may be used for assessing thermal embrittlement of cast stainless steel components.

    9. Light Duty Efficient, Clean Combustion

      SciTech Connect (OSTI)

      Donald Stanton

      2010-12-31

      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.

    10. Light Duty Efficient, Clean Combustion

      SciTech Connect (OSTI)

      Stanton, Donald W

      2011-06-03

      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.

    11. White light velocity interferometer

      DOE Patents [OSTI]

      Erskine, D.J.

      1999-06-08

      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.

    12. Green Light Pulse Oximeter

      DOE Patents [OSTI]

      Scharf, John Edward (Oldsmar, FL)

      1998-11-03

      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.

    13. 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...

    14. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting

      SciTech Connect (OSTI)

      None

      2009-11-01

      A U.S. Department of Energy Solid-State Lighting Gateway Report on a Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting in Lija Loop, Portland, Oregon.

    15. Thermal noise driven computing

      E-Print Network [OSTI]

      Laszlo B. Kish

      2006-10-28

      The possibility of a new type of computing, where thermal noise is the information carrier and the clock in a computer, is studied. The information channel capacity and the lower limit of energy requirement/dissipation are studied in a simple digital system with zero threshold voltage, for the case of error probability close to 0.5, when the thermal noise is equal to or greater than the digital signal. In a simple hypothetical realization of a thermal noise driven gate, the lower limit of energy needed to generate the digital signal is 1.1*kT/bit. The arrangement has potentially improved energy efficiency and it is free of leakage current, crosstalk and ground plane electromagnetic interference problems. Disadvantage is the large number of redundancy elements needed for low-error operation.

    16. Thermal insulated glazing unit

      DOE Patents [OSTI]

      Selkowitz, S.E.; Arasteh, D.K.; Hartmann, J.L.

      1988-04-05

      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.

    17. Thermal insulated glazing unit

      DOE Patents [OSTI]

      Selkowitz, Stephen E. (Piedmont, CA); Arasteh, Dariush K. (Oakland, CA); Hartmann, John L. (Seattle, WA)

      1991-01-01

      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.

    18. Highly directional thermal emitter

      DOE Patents [OSTI]

      Ribaudo, Troy; Shaner, Eric A; Davids, Paul; Peters, David W

      2015-03-24

      A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (.about.64%) at large incidence angles.

    19. Thermal ignition combustion system

      DOE Patents [OSTI]

      Kamo, Roy (Columbus, IN); Kakwani, Ramesh M. (Columbus, IN); Valdmanis, Edgars (Columbus, IN); Woods, Melvins E. (Columbus, IN)

      1988-01-01

      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.degree. C. and a specific heat greater than 480 J/kg.degree. 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.

    20. Thermal ignition combustion system

      DOE Patents [OSTI]

      Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

      1988-04-19

      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.

    1. Cermet fuel thermal conductivity 

      E-Print Network [OSTI]

      Alvis, John Mark

      1988-01-01

      VITA 36 37 40 40 40 40 44 45 47 48 LIST OF FIGURES Figure Unit cell for derivation of model Page Heat Conduction Solution 22 3 Fission Gas Release Model 26 4A Metal Matrix Thermal Conductivity 4B Ceramic Fuel Thermal Conductivity 5... is based on the simple heat conduction equation. It is assumed that there is a uniform distribution of fuel particles in a regular array. A unit cell consists of a cube of matrix material of side length L, containing a spherical fuel particle of radius, r...

    2. 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."

    3. Columbia Water & Light- HVAC and Lighting Efficiency Rebates

      Broader source: Energy.gov [DOE]

      Columbia Water & Light (CWL) offers rebates to its commercial and industrial customers for the purchase of high efficiency HVAC installations and efficient lighting. Incentives for certain...

    4. 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....

    5. Light Vector Mesons

      E-Print Network [OSTI]

      Alexander Milov

      2008-12-21

      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.

    6. lighting in the library

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

      lamp produces about 1750 lumens. Footcandle: a lumen of light distributed over a 1-square-foot (0.09-square-meter) area. Ideal Illumination: the minimum number of footcandles...

    7. Solid State Lighting Reliability

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

      Solid State Lighting Reliability 2015Building Technologies Office Peer Review Lynn Davis, PhD RTI International ldavis@rti.org --- 919-316-3325 Project Summary Timeline: Start...

    8. The Facts of Light

      E-Print Network [OSTI]

      Horn, Berthold K.P.

      This is a random collection of facts about radiant and luminous energy. Some of this information may be useful in the design of photo-diode image sensors, in the set-up of lighting for television microscopes and the ...

    9. National Synchrotron Light Source

      ScienceCinema (OSTI)

      None

      2010-01-08

      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

    10. Lighting in Commercial Buildings

      U.S. Energy Information Administration (EIA) Indexed Site

      5.2 152.6 160.5 54.6 Assembly Health Care Lodging Office 0 20 40 60 80 100 120 140 160 180 Energy Information Administration Energy Consumption Series: Lighting in Commercial...

    11. The detectability of extrasolar planet surroundings - I. Reflected-light photometry of unresolved rings

      E-Print Network [OSTI]

      Luc Arnold; Jean Schneider

      2004-06-09

      It is expected that the next generation of high-contrast imaging instruments will deliver the first unresolved image of an extrasolar planet. The emitted thermal infrared light from the planet should show no phase effect assuming the planet is in thermal equilibrium. But the reflected visible light will vary versus the phase angle. Here, we study the photometric variation of the reflected light versus the orbital phase of a ringed extrasolar planet. We show that a ring around an extrasolar planet, both obviously unresolved, can be detected by its specific photometric signature. A simple quantitative model is discussed, taking into account the basic optical and geometrical properties of the ringed planet.

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

      E-Print Network [OSTI]

      Hardin, Corey Lee

      2011-01-01

      and Background Solar thermal energy collection is anCHANGE THERMAL ENERGY STORAGE FOR CONCENTRATING SOLAR POWERfor Thermal Energy Storage in Concentrated Solar Thermal

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

      E-Print Network [OSTI]

      Hardin, Corey Lee

      2011-01-01

      ENERGY STORAGE FOR CONCENTRATING SOLAR POWER PLANTS,”Thermal Energy Storage in Concentrated Solar Thermal PowerThermal Energy Storage in Concentrated Solar Thermal Power

    14. 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

    15. LED Lighting | Department of Energy

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

      focusing light in ways that are useful in homes and commercial settings. The light-emitting diode (LED) is one of today's most energy-efficient and rapidly-developing lighting...

    16. Energy Conservation in Industrial Lighting 

      E-Print Network [OSTI]

      Meharg, E.

      1979-01-01

      were identified. Savings in power and cost were quantified for typical examples as follows: Task lighting, high light source efficacy, high luminaire mounting height, efficient luminaires, surroundings painted a light color, regular luminaire cleaning...

    17. Higher order light propagation volumes

      E-Print Network [OSTI]

      Martin, Timothy Ly; Martin, Timothy Ly

      2012-01-01

      1.1 Introduction . . . . . . . . . 1.2 Light Propagation4.1.1 Injection of Virtual Point Lights and Geometryof the Stanford bunny, lit by an area light, rendered using

    18. Light as a Healing Mechanism

      E-Print Network [OSTI]

      Lingampalli, Nithya

      2013-01-01

      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

    19. Lighting and the Bottom Line 

      E-Print Network [OSTI]

      Christensen, M.

      1981-01-01

      A discussion of the cost of light and how it relates to the cost of people. The new Illuminating Engineering Society recommended method of determining lighting levels will be explained. Also several ways of providing good lighting to increase...

    20. 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

    1. Phonon-mediated superconducting transitions in layered cuprate superconductors Xiao-Jia Chen, Viktor V. Struzhkin, Zhigang Wu, Russell J. Hemley, and Ho-kwang Mao

      E-Print Network [OSTI]

      Wu, Zhigang

      Phonon-mediated superconducting transitions in layered cuprate superconductors Xiao-Jia Chen series of layered cuprate super- conductors. We show that the dependence of both the superconducting, and cation disorder in the model superconducting series HgBa2Can-1CunO2n+2+ can be well reproduced within one

    2. JOURNAL DE PHYSIQUE Collogue C5, supplement au n 5, Tome 40, Mai 1979, page C5-377 Effect of phonons in mixed valence systems

      E-Print Network [OSTI]

      Boyer, Edmond

      systems like transition metals and rare-earth metals are particularly interesting due to strong electron-phonon coupling on valence fluctuations in rare-earth systems is studied. It is shown that the electron, electronic phase transitions involving f «± d electronic transitions occur in many rare-earth systems like Sm

    3. Thermal Reactor Safety

      SciTech Connect (OSTI)

      Not Available

      1980-06-01

      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.

    4. 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.

      1983-05-01

      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.

    5. Thermal barrier coating

      DOE Patents [OSTI]

      Bowker, Jeffrey Charles (Gibsonia, PA); Sabol, Stephen M. (Orlando, FL); Goedjen, John G. (Oviedo, FL)

      2001-01-01

      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.

    6. New Light Sources for Tomorrow's Lighting Designs 

      E-Print Network [OSTI]

      Krailo, D. A.

      1986-01-01

      and lighting systems. Table 2 shows the development of four-foot energy-saving retrofit lamps. By utilizing new cathode designed and different gas fills, 34-watt energy-saving lamps were developed that operate on existing rapid start ballasts and afford... of fluorescent lamps, two watts of system power are consumed in heating the lamp cath odes. The shedding of cathode heating wattage was the next lamp efficiency improvement to be introduced. One available sy tern dis connects the lamp cathodes from...

    7. Pattern of x-ray scattering by thermal phonons in Si Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Avenue,

      E-Print Network [OSTI]

      Luh, Dah-An

      -2902 and Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 West Green-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 P. Zschack and P. Jemian Frederick Seitz Materials and Engineering, University of Illinois at Urbana-Champaign, 1304 West Green Street, Urbana, Illinois 61801-2980 D

    8. Lighting Design | Department of Energy

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

      as part of your whole-house design -- an approach for building an energy-efficient home. Indoor Lighting Design When designing indoor lighting for energy efficiency,...

    9. GATEWAY Demonstrations: LED Street Lighting

      SciTech Connect (OSTI)

      Cook, Tyson; Shackelford, Jordan; Pang, Terrance Pang

      2008-12-01

      This report summarizes an assessment project conducted to study the performance of light emitting diode (LED) luminaires in a street lighting application in San Francisco, CA.

    10. Interior Lighting Efficiency for Municipalities

      Broader source: Energy.gov [DOE]

      This webinar covered a basic understanding of lighting, different types of lamps and luminaries, importance of energy efficiency in lighting, and knowledge of where to find financial resources.

    11. 2010 US Lighting Market Characterization

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

      2010 U.S. Lighting Market Characterization January 2012 Prepared for: Solid-State Lighting Program Building Technologies Program Office of Energy Efficiency and Renewable Energy...

    12. Lighting Controls | Department of Energy

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

      fluorescent lighting fixtures rather than replace them. Dimmers and LEDs Some light-emitting diode (LED) lightbulbs can be used with dimmers. LED bulbs and fixtures must be...

    13. Medical catheters thermally manipulated by fiber optic bundles

      DOE Patents [OSTI]

      Chastagner, P.

      1992-10-06

      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.

    14. Simultaneous sensing of light and sound velocities of fluids in a two-dimensional phoXonic crystal with defects

      SciTech Connect (OSTI)

      Amoudache, Samira; Pennec, Yan Djafari Rouhani, Bahram; Khater, Antoine; Lucklum, Ralf; Tigrine, Rachid

      2014-04-07

      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.

    15. Influence of atomic collisions on spectrum of light scattered from an f-deformed Bose-Einstein condensate

      E-Print Network [OSTI]

      Z. Haghshenasfard; M. H. Naderi; M. Soltanolkotabi

      2008-07-11

      In this paper, we investigate the spectrum of light scattered from a Bose-Einstein condensate in the framework of f-deformed boson. We use an f-deformed quantum model in which the Gardiners phonon operators for BEC are deformed by an operator-valued function, f(n), of the particle-number operator n. We consider the collisions between the atoms as a special kind of f-deformation. The collision rate k is regarded as the deformation parameter and the spectrum of light scattered from the deformed BEC is analyzed. In particular, we find that with increasing the values of deformation parameters k and eta=1/N (N, total number of condensate atoms) the scattering spectrum shows deviation from the spectrum associated with nondeformed Bose-Einstein condensate.

    16. 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

    17. 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

    18. 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

    19. Demonstration Assessment of LED Roadway Lighting: Philadelphia...

      Office of Scientific and Technical Information (OSTI)

      LED Roadway Lighting: Philadelphia, PA Royer, Michael P.; Tuenge, Jason R.; Poplawski, Michael E. Roadway Lighting; Solid-state lighting; LED lighting; SSL; LED; GATEWAY Roadway...

    20. Lighting Principles and Terms | Department of Energy

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

      Principles and Terms Lighting Principles and Terms Light quantity, energy consumption, and light quality are the basic principles of lighting. | Photo courtesy of