Universal modal radiation laws for all thermal emitters

PubMed Central

Zhu, Linxiao; Fan, Shanhui

2017-01-01

We derive four laws relating the absorptivity and emissivity of thermal emitters. Unlike the original Kirchhoff radiation law derivations, these derivations include diffraction, and so are valid also for small objects, and can also cover nonreciprocal objects. The proofs exploit two recent approaches. First, we express all fields in terms of the mode-converter basis sets of beams; these sets, which can be uniquely established for any linear optical object, give orthogonal input beams that are coupled one-by-one to orthogonal output beams. Second, we consider thought experiments using universal linear optical machines, which allow us to couple appropriate beams and black bodies. Two of these laws can be regarded as rigorous extensions of previously known laws: One gives a modal version of a radiation law for reciprocal objects—the absorptivity of any input beam equals the emissivity into the “backward” (i.e., phase-conjugated) version of that beam; another gives the overall equality of the sums of the emissivities and the absorptivities for any object, including nonreciprocal ones. The other two laws, valid for reciprocal and nonreciprocal objects, are quite different from previous relations. One shows universal equivalence of the absorptivity of each mode-converter input beam and the emissivity into its corresponding scattered output beam. The other gives unexpected equivalences of absorptivity and emissivity for broad classes of beams. Additionally, we prove these orthogonal mode-converter sets of input and output beams are the ones that maximize absorptivities and emissivities, respectively, giving these beams surprising additional physical meaning. PMID:28396436

Implications for the Cosmological Landscape: Can Thermal Inputs from a Prior Universe Account for Relic Graviton Production?

NASA Astrophysics Data System (ADS)

Beckwith, A. W.

2008-01-01

Sean Carroll's pre-inflation state of low temperature-low entropy provides a bridge between two models with different predictions. The Wheeler-de Witt equation provides thermal input into today's universe for graviton production. Also, brane world models by Sundrum allow low entropy conditions, as given by Carroll & Chen (2005). Moreover, this paper answers the question of how to go from a brane world model to the 10 to the 32 power Kelvin conditions stated by Weinberg in 1972 as necessary for the initiation of quantum gravity processes. This is a way of getting around the fact CMBR is cut off at a red shift of z = 1100. This paper discusses the difference in values of the upper bound of the cosmological constant between a large upper bound predicated for a temperature dependent vacuum energy predicted by Park (2002), and the much lower bound predicted by Barvinsky (2006). with the difference in values in vacuum energy contributing to relic graviton production. This paper claims that this large thermal influx, with a high initial cosmological constant and a large region of space for relic gravitons interacting with space-time up to the z = 1100 CMBR observational limit are interlinked processes delineated in the Lloyd (2002) analogy of the universe as a quantum computing system. Finally, the paper claims that linking a shrinking prior universe via a worm hole solution for a pseudo time dependent Wheeler-De Witt equation permits graviton generation as thermal input from the prior universe, transferred instantaneously to relic inflationary conditions today. The existence of a wormhole is presented as a necessary condition for relic gravitons. Proving the sufficiency of the existence of a worm hole for relic gravitons is a future project.

Assessing heat-related health risk in Europe via the Universal Thermal Climate Index (UTCI).

PubMed

Di Napoli, Claudia; Pappenberger, Florian; Cloke, Hannah L

2018-03-15

In this work, the potential of the Universal Thermal Climate Index (UTCI) as a heat-related health risk indicator in Europe is demonstrated. The UTCI is a bioclimate index that uses a multi-node human heat balance model to represent the heat stress induced by meteorological conditions to the human body. Using 38 years of meteorological reanalysis data, UTCI maps were computed to assess the thermal bioclimate of Europe for the summer season. Patterns of heat stress conditions and non-thermal stress regions are identified across Europe. An increase in heat stress up to 1 °C is observed during recent decades. Correlation with mortality data from 17 European countries revealed that the relationship between the UTCI and death counts depends on the bioclimate of the country, and death counts increase in conditions of moderate and strong stress, i.e., when UTCI is above 26 and 32 °C. The UTCI's ability to represent mortality patterns is demonstrated for the 2003 European heatwave. These findings confirm the importance of UTCI as a bioclimatic index that is able to both capture the thermal bioclimatic variability of Europe, and relate such variability with the effects it has on human health.

Spectral Performance of a Composite Single-Crystal Filtered Thermal Neutron Beam for BNCT Research at the University of Missouri

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Brockman; D. W. Nigg; M. F. Hawthorne

2009-07-01

Parameter studies, design calculations and initial neutronic performance measurements have been completed for a new thermal neutron beamline to be used for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The calculated and measured thermal neutron fluxes produced at the irradiation location are 9.6x108 and 8.8x108 neutrons/cm2-s, respectively. Calculated and measured cadmium ratios (Au foils) are 217 and 132. These results indicate a well-thermalized neutron spectrum with sufficient thermal neutron flux formore » a variety of small animal BNCT studies.« less

Operando Evidence for a Universal Oxygen Evolution Mechanism on Thermal and Electrochemical Iridium Oxides.

PubMed

Saveleva, Viktoriia A; Wang, Li; Teschner, Detre; Jones, Travis; Gago, Aldo S; Friedrich, K Andreas; Zafeiratos, Spyridon; Schlögl, Robert; Savinova, Elena R

2018-06-07

Progress in the development of proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for an understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation-based near-ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers-electrochemical and thermal iridium oxides. Analysis of the O K-edge and Ir 4f spectra backed by density functional calculations reveals a universal oxygen anion red-ox mechanism regardless of the nature (electrochemical or thermal) of the iridium oxide. The formation of molecular oxygen is considered to occur through a chemical step from the electrophilic O I- species, which itself is formed in an electrochemical step.

Towards understanding thermal history of the Universe through direct and indirect detection of dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roszkowski, Leszek; Trojanowski, Sebastian; Turzyński, Krzysztof, E-mail: leszek.roszkowski@ncbj.gov.pl, E-mail: sebastian.trojanowski@uci.edu, E-mail: Krzysztof-Jan.Turzynski@fuw.edu.pl

We examine the question to what extent prospective detection of dark matter by direct and indirect- detection experiments could shed light on what fraction of dark matter was generated thermally via the freeze-out process in the early Universe. By simulating putative signals that could be seen in the near future and using them to reconstruct WIMP dark matter properties, we show that, in a model- independent approach this could only be achieved in a thin sliver of the parameter space. However, with additional theoretical input the hypothesis about the thermal freeze-out as the dominant mechanism for generating dark matter canmore » potentially be verified. We illustrate this with two examples: an effective field theory of dark matter with a vector messenger and a higgsino or wino dark matter within the MSSM.« less

The universal toolbox thermal imager

NASA Astrophysics Data System (ADS)

Hollock, Steve; Jones, Graham; Usowicz, Paul

2003-09-01

The Introduction of Microsoft Pocket PC 2000/2002 has seen a standardisation of the operating systems used by the majority of PDA manufacturers. This, coupled with the recent price reductions associated with these devices, has led to a rapid increase in the sales of such units; their use is now common in industrial, commercial and domestic applications throughout the world. This paper describes the results of a programme to develop a thermal imager that will interface directly to all of these units so as to take advantage of the existing and future installed base of such devices. The imager currently interfaces with virtually any Pocket PC which provides the necessary processing, display and storage capability; as an alternative, the output of the unit can be visualised and processed in real time using a PC or laptop computer. In future, the open architecture employed by this imager will allow it to support all mobile computing devices, including phones and PDAs. The imager has been designed for one-handed or two-handed operation so that it may be pointed at awkward angles or used in confined spaces; this flexibility of use coupled with the extensive feature range and exceedingly low-cost of the imager, is extending the marketplace for thermal imaging from military and professional, through industrial to the commercial and domestic marketplaces.

University Students Explaining Adiabatic Compression of an Ideal Gas—A New Phenomenon in Introductory Thermal Physics

NASA Astrophysics Data System (ADS)

Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.

2012-12-01

This study focuses on second-year university students' explanations and reasoning related to adiabatic compression of an ideal gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their previous upper secondary school knowledge. The students' explanations and reasoning were investigated with the aid of paper and pencil tests ( n = 86) and semi-structured interviews ( n = 5) at the start of a thermal physics course at the University of Eastern Finland. The paper and pencil test revealed that the students had difficulties in applying content taught during earlier education in a new context: only a few of them were able to produce a correct explanation for the phenomenon. A majority of the students used either explanations with invalid but physically correct models, such as the ideal gas law or a microscopic model, or erroneous dependencies between quantities. The results also indicated that students had problems in seeing deficiencies or inconsistencies in their reasoning, in both test and interview situations. We suggest in our conclusion that the contents of upper secondary school thermal physics courses should be carefully examined to locate the best emphases for different laws, principles, concepts, and models. In particular, the limitations of models should be made explicit in teaching and students should be guided towards critical scientific thinking, including metaconceptual awareness.

Thermal Preference Ranges Correlate with Stable Signals of Universal Stress Markers in Lake Baikal Endemic and Holarctic Amphipods

PubMed Central

Axenov-Gribanov, Denis; Bedulina, Daria; Shatilina, Zhanna; Jakob, Lena; Vereshchagina, Kseniya; Lubyaga, Yulia; Gurkov, Anton; Shchapova, Ekaterina; Luckenbach, Till; Lucassen, Magnus; Sartoris, Franz Josef; Pörtner, Hans-Otto; Timofeyev, Maxim

2016-01-01

Temperature is the most pervasive abiotic environmental factor for aquatic organisms. Fluctuations in temperature range lead to changes in metabolic performance. Here, we aimed to identify whether surpassing the thermal preference zones is correlated with shifts in universal cellular stress markers of protein integrity, responses to oxidative stress and lactate content, as indicators of anaerobic metabolism. Exposure of the Lake Baikal endemic amphipod species Eulimnogammarus verrucosus (Gerstfeldt, 1858), Ommatogammarus flavus (Dybowski, 1874) and of the Holarctic amphipod Gammarus lacustris Sars 1863 (Amphipoda, Crustacea) to increasing temperatures resulted in elevated heat shock protein 70 (Hsp70) and lactate content, elevated antioxidant enzyme activities (i.e., catalase and peroxidase), and reduced lactate dehydrogenase and glutathione S-transferase activities. Thus, the zone of stability (absence of any significant changes) of the studied molecular and biochemical markers correlated with the behaviorally preferred temperatures. We conclude that the thermal behavioral responses of the studied amphipods are directly related to metabolic processes at the cellular level. Thus, the determined thermal ranges may possibly correspond to the thermal optima. This relationship between species-specific behavioral reactions and stress response metabolism may have significant ecological consequences that result in a thermal zone-specific distribution (i.e., depths, feed spectrum, etc.) of species. As a consequence, by separating species with different temperature preferences, interspecific competition is reduced, which, in turn, increases a species’ Darwinian fitness in its environment. PMID:27706227

Human-biometeorological conditions in the southern Baltic coast based on the universal thermal climate index (UTCI)

NASA Astrophysics Data System (ADS)

Kolendowicz, Leszek; Półrolniczak, Marek; Szyga-Pluta, Katarzyna; Bednorz, Ewa

2017-10-01

The paper focuses on bioclimatic conditions in the southern part of the Baltic coast based on universal thermal climate index values. Taking into consideration the observational data from coastline stations as well as reanalysis data from the National Center for Environmental Prediction and National Center for Atmospheric Research (sea level pressure and the 500 hPa geopotential height), the authors attempt to explain which of the synoptic situations are responsible for the occurrence of days with very strong and extreme cold or heat stress. The obtained results confirm that the extreme thermal heat and cold stress conditions are for the most part associated with high-pressure systems. The researched area is usually situated in the western or southern periphery of the anticyclones. The cold stress also occurs during the advection from west or northwest, caused by the direct influence of a low-pressure system whose center is situated over the North Sea, southern Scandinavia, or the southern Baltic Sea.

University Students' Understanding of Thermal Physics in Everyday Contexts

ERIC Educational Resources Information Center

Georgiou, Helen; Sharma, Manjula Devi

2012-01-01

Thermal physics is in the realm of everyday experience, underlies current environmental concerns, and underpins studies in sciences, health and engineering. In the state of NSW in Australia, the coverage of thermal topics in high school is minimal, and, hence, so is the conceptual understanding of students. This study takes a new approach at…

University of Minnesota Aquifer Thermal Energy Storage (ATES) project report on the first long-term cycle

NASA Astrophysics Data System (ADS)

Walton, M.

1991-10-01

The technical feasibility of high-temperature (greater than 100 C) aquifer thermal energy storage (IOTAS) in a deep, confined aquifer was tested in a series of experimental cycles at the University of Minnesota's St. Paul field test facility (FTF). This report describes the additions to the FTF for the long-term cycles and the details of the first long-term cycle (LT1) that was conducted from November 1984 through May 1985. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic aspects of LT1 are reported. The permits for long-term cycles required the addition of a monitoring well 30.5 m from the storage well for monitoring near the edge of the thermally affected area and allowed the addition of a cation-exchange water softener to enable continuous operation during the injection phase. Approximately 62 percent of the 9.47 GWh of energy added to the 9.21 x 10(exp 4) cu m of ground water stored in the aquifer LT1 was recovered. Ion-exchange water softening of the heated and stored ground water prevented scaling in the system heat exchangers and the storage well and changed the major-ion chemistry of the stored water. Temperatures at the storage horizons in site monitoring wells reached as high as 108 C during the injection phase of LT1. Following heat recovery, temperatures were less than 30 C at the same locations. Less permeable horizons underwent slow temperature changes. No thermal or chemical effects were observed at the remote monitoring site.

Reply to ``Comment on `Ratchet universality in the presence of thermal noise' ''

NASA Astrophysics Data System (ADS)

Martínez, Pedro J.; Chacón, Ricardo

2013-12-01

The Comment by Quintero [preceding Comment, Phys. Rev. E10.1103/PhysRevE.88.066101 88, 066101 (2013)] does not dispute the central result of our paper [Martínez and Chacón, Phys. Rev. E10.1103/PhysRevE.87.062114 87, 062114 (2013)], which is a theory explaining the interplay between thermal noise and symmetry breaking in the ratchet transport of a Brownian particle moving on a periodic substrate subjected to a temporal biharmonic excitation γ[ηsin(ωt)+α(1-η)sin(2ωt+φ)]. In the Comment, the authors claim, on the sole basis of their numerical simulations for the particular case α=2, that “there is no such universal force waveform and that the evidence obtained by the authors otherwise is due to their particular choice of parameters.” Here we demonstrate by means of theoretical arguments and additional numerical simulations that all the conclusions of our original article are preserved.

Mars Thermal Inertia

NASA Technical Reports Server (NTRS)

2001-01-01

This image shows the global thermal inertia of the Martian surface as measured by the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor. The data were acquired during the first 5000 orbits of the MGS mapping mission. The pattern of inertia variations observed by TES agrees well with the thermal inertia maps made by the Viking Infrared Thermal Mapper experiment, but the TES data shown here are at significantly higher spatial resolution (15 km versus 60 km).

The TES instrument was built by Santa Barbara Remote Sensing and is operated by Philip R. Christensen, of Arizona State University, Tempe, AZ.

Reply to "Comment on 'Ratchet universality in the presence of thermal noise' ".

PubMed

Martínez, Pedro J; Chacón, Ricardo

2013-12-01

The Comment by Quintero et al. [preceding Comment, Phys. Rev. E 88, 066101 (2013)] does not dispute the central result of our paper [Martínez and Chacón, Phys. Rev. E 87, 062114 (2013)], which is a theory explaining the interplay between thermal noise and symmetry breaking in the ratchet transport of a Brownian particle moving on a periodic substrate subjected to a temporal biharmonic excitation γ[ηsin(ωt)+α(1-η)sin(2ωt+φ)]. In the Comment, the authors claim, on the sole basis of their numerical simulations for the particular case α=2, that "there is no such universal force waveform and that the evidence obtained by the authors otherwise is due to their particular choice of parameters." Here we demonstrate by means of theoretical arguments and additional numerical simulations that all the conclusions of our original article are preserved.

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore

PubMed Central

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2017-01-01

A stable nanoscale thermal hot spot, with temperature approaching 100 °C, is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z, collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte. PMID:27715110

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore

NASA Astrophysics Data System (ADS)

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2016-09-01

A stable nanoscale thermal hot spot, with temperature approaching 100 °C , is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z , collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte.

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore.

PubMed

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2016-09-23

A stable nanoscale thermal hot spot, with temperature approaching 100 °C, is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z, collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte.

Universal depinning transition of domain walls in ultrathin ferromagnets

NASA Astrophysics Data System (ADS)

Diaz Pardo, R.; Savero Torres, W.; Kolton, A. B.; Bustingorry, S.; Jeudy, V.

2017-05-01

We present a quantitative and comparative study of magnetic-field-driven domain-wall depinning transition in different ferromagnetic ultrathin films over a wide range of temperature. We reveal a universal scaling function accounting for both drive and thermal effects on the depinning transition, including critical exponents. The consistent description we obtain for both the depinning and subthreshold thermally activated creep motion should shed light on the universal glassy dynamics of thermally fluctuating elastic objects pinned by disordered energy landscapes.

Thermal fluctuations of dark matter in bouncing cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Changhong, E-mail: changhongli@ynu.edu.cn

We investigate the statistical nature of the dark matter particles produced in bouncing cosmology, especially, the evolution of its thermal fluctuations. By explicitly deriving and solving the equation of motion of super-horizon mode, we fully determine the evolution of thermal perturbation of dark matter in a generic bouncing background. And we also show that the evolution of super-horizon modes is stable and will not ruin the background evolution of a generic bouncing universe till the Planck scale. Given no super-horizon thermal perturbation of dark matter appears in standard inflation scenario such as WIMP(-less) miracles, such super-horizon thermal perturbation of darkmore » matter generated during the generic bouncing universe scenario may be significant for testing and distinguishing these two scenario in near future.« less

Thermalization after/during reheating

NASA Astrophysics Data System (ADS)

Harigaya, Keisuke; Mukaida, Kyohei

2014-05-01

If reheating of the Universe takes place via Planck-suppressed decay, it seems that the thermalization of produced particles might be delayed, since they have large energy/small number densities and number violating large angle scatterings which decrease the momentum of particles by large amount are inefficient correspondingly. In this paper, we study the thermalization of such "under occupied" decay products in detail, following recent developments in understanding the thermalization of non-abelian plasma. Contrary to the above naive expectation, it is shown that in most cases thermalization after/during reheating occurs instantaneously by properly taking account of scatterings with small angles and of particles with small momenta. In particular, the condition for instantaneous thermalization before the completion of reheating is found to be , which is much milder than that obtained in previous works with small angle scatterings taken into account.

Study of Aquifer Thermal Energy Storage

NASA Astrophysics Data System (ADS)

Okuyama, Masaaki; Umemiya, Hiromichi; Shibuya, Ikuko; Haga, Eiji

Yamagata University 'Aquifer Thermal Energy Storage (ATES)' is the experimental system which has been running since 1982. From the results for along terms of experiments, we obtain many important knowledge. This paper presents the accomplishments for 16 years and the characteristics of thermal energy storage in thermal energy storage well. The conclusions show as follows. 1)In recent years, the thermal recovery factor of warm energy storage well becomes almost constant at about 60%. 2) The thermal recovery factor of cool energy storage well increases gradually and becomes at about 15%. 3) Since the ferric colloidal dam is formed in aquifer, thermal recovery factor increase year after year. 4) Back wash can remove clogging for ferric colloidal dam. 5) The apparent thermal diffusivity decrease gradually due to ferric colloidal dam.

Global Map of Thermal Neutrons

NASA Technical Reports Server (NTRS)

2002-01-01

Observations by NASA's 2001 Mars Odyssey spacecraft show a global view of Mars in low energy, or thermal, neutrons. Thermal neutrons are sensitive to the presence of hydrogen and the presence of carbon dioxide, in this case 'dry ice' frost. The red area at the top of the map indicates that about one meter (three feet) of carbon dioxide frost covers the surface, as it does every Mars winter in the polar regions. Soil enriched by hydrogen is indicated by the deep blue colors on the map, which show a low intensity of thermal neutrons. An enhancement of thermal neutrons close to the south pole, seen as a light green color, indicates the presence of residual carbon dioxide in the south polar cap, even though the annual frost dissipated from that region during southern summer.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. Investigators at Arizona State University in Tempe, the University of Arizona in Tucson, and NASA's Johnson Space Center, Houston, operate the science instruments. The gamma-ray spectrometer was provided by the University of Arizona in collaboration with the Russian Aviation and Space Agency, which provided the high-energy neutron detector, and the Los Alamos National Laboratories, New Mexico, which provided the neutron spectrometer. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

The Multi-Universe Cosmos. The Origin and Fate of our Universe

NASA Astrophysics Data System (ADS)

Velan, Karel

18 billion yers ago our Universe, one of many in the Cosmos, emerged from a hot, dense fireball of matter and energy created in the 4-dimensional cosmic space-time from virtual particles receiving their rest mass from a powerful primordial radiation field, the missing link to any viable theory of creation. The cloud of elementary particles and radiation collapsed by gravity into a fireball until its trappped thermal radiation caused a titanic explosion that initiated the expansion and evolution of ours universe. As the universe expanded and cooled it spawned galaxies, stars, planets and life. Proven laws of physics, observationsl data and mathematical computations support the new cosmological model which proposes a large number of universes in the cosmos in varying stages of evolution

Quantum cloning disturbed by thermal Davies environment

NASA Astrophysics Data System (ADS)

Dajka, Jerzy; Łuczka, Jerzy

2016-06-01

A network of quantum gates designed to implement universal quantum cloning machine is studied. We analyze how thermal environment coupled to auxiliary qubits, `blank paper' and `toner' required at the preparation stage of copying, modifies an output fidelity of the cloner. Thermal environment is described in terms of the Markovian Davies theory. We show that such a cloning machine is not universal any more but its output is independent of at least a part of parameters of the environment. As a case study, we consider cloning of states in a six-state cryptography's protocol. We also briefly discuss cloning of arbitrary input states.

PREFACE: Eurotherm Seminar 102: Thermal Management of Electronic Systems

NASA Astrophysics Data System (ADS)

Punch, J.; Walsh, E.

2014-07-01

About EUROTHERM The aim of the EUROTHERM Committee (www.eurothermcommittee.eu) is to promote and foster European cooperation in Thermal Sciences and Heat Transfer by gathering together scientists and engineers working in specialized areas. The Committee consists of members representing and appointed by national bodies in the EU countries. The current President of EUROTHERM is Professor Anton van Steenhoven from the University of Eindhoven (The Netherlands). The Committee organizes and coordinates European scientific events such as the EUROTHERM Seminars (about 4 per year) and the European Thermal Sciences Conference (every 4 years). About EUROTHERM Seminar 102 (www.eurothermseminar102.com) This seminar, part of the long-running series of European seminars on the thermal sciences, took place in June 2014 at the University of Limerick in Limerick, Ireland. The seminar addressed the topic of 'Thermal Management of Electronic Systems', a critical contemporary application area which represents a vibrant challenge for practitioners of the thermal sciences. We convey special thanks to the reviewers who have evaluated these papers. We also thank the scientific committee, consisting of internationally recognized experts. Their role has been to manage the evaluation of abstracts and the papers selection process as co-coordinators for specific topics. This seminar was hosted by the Stokes Institute at the University of Limerick. It could not have been organized without the efficient help of our administrators and technicians for IT support. This volume of Journal of Physics: Conference Series includes 27 articles presented at the seminar. Dr. Jeff Punch, Chair Stokes Institute, University of Limerick, Limerick, Ireland Email: jeff.punch@ul.ie Prof. Edmond Walsh, Co-Chair Associate Professor, Osney Laboratories, Department of Engineering Science, University of Oxford, UK Email: edmond.walsh@bnc.ox.ac.uk

Uncooled thermal imaging and image analysis

NASA Astrophysics Data System (ADS)

Wang, Shiyun; Chang, Benkang; Yu, Chunyu; Zhang, Junju; Sun, Lianjun

2006-09-01

Thermal imager can transfer difference of temperature to difference of electric signal level, so can be application to medical treatment such as estimation of blood flow speed and vessel 1ocation [1], assess pain [2] and so on. With the technology of un-cooled focal plane array (UFPA) is grown up more and more, some simple medical function can be completed with un-cooled thermal imager, for example, quick warning for fever heat with SARS. It is required that performance of imaging is stabilization and spatial and temperature resolution is high enough. In all performance parameters, noise equivalent temperature difference (NETD) is often used as the criterion of universal performance. 320 x 240 α-Si micro-bolometer UFPA has been applied widely presently for its steady performance and sensitive responsibility. In this paper, NETD of UFPA and the relation between NETD and temperature are researched. several vital parameters that can affect NETD are listed and an universal formula is presented. Last, the images from the kind of thermal imager are analyzed based on the purpose of detection persons with fever heat. An applied thermal image intensification method is introduced.

Determining in-situ thermal conductivity of coarse textured materials through numerical analysis of thermal

NASA Astrophysics Data System (ADS)

Saito, H.; Hamamoto, S.; Moldrup, P.; Komatsu, T.

2013-12-01

Ground source heat pump (GSHP) systems use ground or groundwater as a heat/cooling source, typically by circulating anti-freezing solution inside a vertically installed closed-loop tube known as a U-tube to transfer heat to/from the ground. Since GSHP systems are based on renewable energy and can achieve much higher coefficient of performance (COP) than conventional air source heat pump systems, use of GSHP systems has been rapidly increasing worldwide. However, environmental impacts by GSHP systems including thermal effects on subsurface physical-chemical and microbiological properties have not been fully investigated. To rigorously assess GSHP impact on the subsurface environment, ground thermal properties including thermal conductivity and heat capacity need to be accurately characterized. Ground thermal properties were investigated at two experimental sites at Tokyo University of Agriculture and Technology (TAT) and Saitama University (SA), both located in the Kanto area of Japan. Thermal properties were evaluated both by thermal probe measurements on boring core samples and by performing in-situ Thermal Response Tests (TRT) in 50-80 m deep U-tubes. At both TAT and SU sites, heat-pulse probe measurements gave unrealistic low thermal conductivities for coarse textured materials (dominated by particles > 75 micrometers). Such underestimation can be partly due to poor contact between probe and porous material and partly to markedly decreasing sample water content during drilling, carrying, and storing sandy/gravelly samples. A more reliable approach for estimating in-situ thermal conductivity of coarse textured materials is therefore needed, and may be based on the commonly used TRT test. However, analyses of TRT data is typically based on Kelvin's line source model and provides an average (effective) thermal property for the whole soil profile around the U-tube but not for each geological layer. The main objective of this study was therefore to develop a method

Finite-size scaling of eigenstate thermalization

NASA Astrophysics Data System (ADS)

Beugeling, W.; Moessner, R.; Haque, Masudul

2014-04-01

According to the eigenstate thermalization hypothesis (ETH), even isolated quantum systems can thermalize because the eigenstate-to-eigenstate fluctuations of typical observables vanish in the limit of large systems. Of course, isolated systems are by nature finite and the main way of computing such quantities is through numerical evaluation for finite-size systems. Therefore, the finite-size scaling of the fluctuations of eigenstate expectation values is a central aspect of the ETH. In this work, we present numerical evidence that for generic nonintegrable systems these fluctuations scale with a universal power law D-1/2 with the dimension D of the Hilbert space. We provide heuristic arguments, in the same spirit as the ETH, to explain this universal result. Our results are based on the analysis of three families of models and several observables for each model. Each family includes integrable members and we show how the system size where the universal power law becomes visible is affected by the proximity to integrability.

Primordial perturbations in a rainbow universe with running Newton constant

NASA Astrophysics Data System (ADS)

Brighenti, Francesco; Gubitosi, Giulia; Magueijo, Joao

2017-03-01

We compute the spectral index of primordial perturbations in a rainbow universe. We allow the Newton constant G to run at (super-) Planckian energies and we consider both vacuum and thermal perturbations. If the rainbow metric is the one associated to a generalized Horava-Lifshitz dispersion relation, we find that only when G tends asymptotically to 0 can one match the observed value of the spectral index and solve the horizon problem, both for vacuum and thermal perturbations. For vacuum fluctuations the observational constraints imply that the primordial universe expansion can be both accelerating or decelerating, while in the case of thermal perturbations only decelerating expansion is allowed.

JPL Advanced Thermal Control Technology Roadmap - 2012

NASA Technical Reports Server (NTRS)

Birur, Gaj; Rodriguez, Jose I.

2012-01-01

NASA's new emphasis on human exploration program for missions beyond LEO requires development of innovative and revolutionary technologies. Thermal control requirements of future NASA science instruments and missions are very challenging and require advanced thermal control technologies. Limited resources requires organizations to cooperate and collaborate; government, industry, universities all need to work together for the successful development of these technologies.

78 FR 29393 - University of Missouri-Columbia Facility Operating License No. R-103

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-20

... Curators of the University of Missouri--Columbia (the licensee) to operate the Missouri University Research Reactor (MURR) at a maximum steady-state thermal power of 10 megawatts (MW). The renewed license would authorize the licensee to operate the MURR up to a steady-state thermal power of 10 MW for an additional 20...

THERMAL DEPOLYMERIZATION OF POSTCONSUMER PLASTICS

EPA Science Inventory

The University of North Dakota Energy & Environmental Research Center (EERC) performed two series of tests to evaluate process conditions for thermal depolymerization of postconsumer plastics. The objective of the first test series was to provide data for optimization of reactio...

USAF solar thermal applications overview

NASA Technical Reports Server (NTRS)

Hauger, J. S.; Simpson, J. A.

1981-01-01

Process heat applications were compared to solar thermal technologies. The generic process heat applications were analyzed for solar thermal technology utilization, using SERI's PROSYS/ECONOMAT model in an end use matching analysis and a separate analysis was made for solar ponds. Solar technologies appear attractive in a large number of applications. Low temperature applications at sites with high insolation and high fuel costs were found to be most attractive. No one solar thermal technology emerges as a clearly universal or preferred technology, however,, solar ponds offer a potential high payoff in a few, selected applications. It was shown that troughs and flat plate systems are cost effective in a large number of applications.

Thermal Analysis

NASA Technical Reports Server (NTRS)

1986-01-01

The University of Georgia used NASTRAN, a COSMIC program that predicts how a design will stand up under stress, to develop a model for monitoring the transient cooling of vegetables. The winter use of passive solar heating for poultry houses is also under investigation by the Agricultural Engineering Dept. Another study involved thermal analysis of black and green nursery containers. The use of NASTRAN has encouraged student appreciation of sophisticated computer analysis.

Tensile Bond Strength of So-called Universal Primers and Universal Multimode Adhesives to Zirconia and Lithium Disilicate Ceramics.

PubMed

Elsayed, Adham; Younes, Feras; Lehmann, Frank; Kern, Matthias

2017-01-01

To test the bond strength and durability after artificial aging of so-called universal primers and universal multimode adhesives to lithium disilicate or zirconia ceramics. A total of 240 ceramic plates, divided into two groups, were produced and conditioned: 120 acid-etched lithium disilicate plates (IPS e.max CAD) and 120 air-abraded zirconia plates (Zenostar T). Each group was divided into five subgroups (n = 24), and a universal restorative primer or multimode universal adhesive was used for each subgroup to bond plexiglas tubes filled with a composite resin to the ceramic plate. The specimens were stored in water at 37°C for 3 days without thermal cycling, or for 30 or 150 days with 7500 or 37,500 thermal cycles between 5°C and 55°C, respectively. All specimens then underwent tensile bond strength testing. Initially, all bonding systems exhibited high TBS, but some showed a significant reduction after 30 and 150 days of storage. After 3, 30, and 150 days, Monobond Plus, which contains silane and phosphate monomer, showed significantly higher bond strengths than the other universal primer and adhesive systems. The bond strength to lithium disilicate and zirconia ceramic is significantly affected by the bonding system used. Using a separate primer containg silane and phosphate monomer provides more durable bonding than do silanes incorporated in universal multimode adhesives. Only one of five so-called universal primers and adhesives provided durable bonding to lithium disilicate and zirconia ceramic.

Creation of the universe

NASA Astrophysics Data System (ADS)

Fang, Li Zhi; Li, Shu Xian

Philosophical aspects of current cosmological theories are explored in an introduction for general readers. Chapters are devoted to the physical implications of an ancient Chinese story, expansion without a center, the age of the universe, the finiteness or infiniteness of space, visible and invisible matter, the birth of order from chaos, and the thermal history of the universe. Consideration is given to the synthesis of elements, the origin of asymmetry, the inflation of vacuum, the physics of the first move, and the anthropic principle and physical constants. Diagrams and drawings are provided.

Microwave Thermal Propulsion

NASA Technical Reports Server (NTRS)

Parkin, Kevin L. G.; Lambot, Thomas

2017-01-01

We have conducted research in microwave thermal propulsion as part of the space exploration access technologies (SEAT) research program, a cooperative agreement (NNX09AF52A) between NASA and Carnegie Mellon University. The SEAT program commenced on the 19th of February 2009 and concluded on the 30th of September 2015. The DARPA/NASA Millimeter-wave Thermal Launch System (MTLS) project subsumed the SEAT program from May 2012 to March 2014 and one of us (Parkin) served as its principal investigator and chief engineer. The MTLS project had no final report of its own, so we have included the MTLS work in this report and incorporate its conclusions here. In the six years from 2009 until 2015 there has been significant progress in millimeter-wave thermal rocketry (a subset of microwave thermal rocketry), most of which has been made under the auspices of the SEAT and MTLS programs. This final report is intended for multiple audiences. For researchers, we present techniques that we have developed to simplify and quantify the performance of thermal rockets and their constituent technologies. For program managers, we detail the facilities that we have built and the outcomes of experiments that were conducted using them. We also include incomplete and unfruitful lines of research. For decision-makers, we introduce the millimeter-wave thermal rocket in historical context. Considering the economic significance of space launch, we present a brief but significant cost-benefit analysis, for the first time showing that there is a compelling economic case for replacing conventional rockets with millimeter-wave thermal rockets.

Identifying Indicators of Progress in Thermal Spray Research Using Bibliometrics Analysis

NASA Astrophysics Data System (ADS)

Li, R.-T.; Khor, K. A.; Yu, L.-G.

2016-12-01

We investigated the research publications on thermal spray in the period of 1985-2015 using the data from Web of Science, Scopus and SciVal®. Bibliometrics analysis was employed to elucidate the country and institution distribution in various thermal spray research areas and to characterize the trends of topic change and technology progress. Results show that China, USA, Japan, Germany, India and France were the top countries in thermal spray research, and Xi'an Jiaotong University, Universite de Technologie Belfort-Montbeliard, Shanghai Institute of Ceramics, ETH Zurich, National Research Council of Canada, University of Limoges were among the top institutions that had high scholarly research output during 2005-2015. The terms of the titles, keywords and abstracts of the publications were analyzed by the Latent Dirichlet Allocation model and visually mapped using the VOSviewer software to reveal the progress of thermal spray technology. It is found that thermal barrier coating was consistently the main research area in thermal spray, and high-velocity oxy-fuel spray and cold spray developed rapidly in the last 10 years.

Spatial differentiation of China's summer tourist destinations based on climatic suitability using the Universal Thermal Climate Index

NASA Astrophysics Data System (ADS)

Yang, Jun; Zhang, Zhenchao; Li, Xueming; Xi, Jianchao; Feng, Zhangxian

2017-11-01

As a result of global warming and the gradual exacerbation of the urban heat island effect, vacationing in the summer to escape the heat has become a compelling tourism demand. This study examines the spatial differentiation of China's summer tourist destinations based on meteorological observations and tourism resources data from 1960 to 2014. The Universal Thermal Climate Index and analytic hierarchy process model were used to analyze climatic suitability. The findings are as follows. First, the spatial distribution of China's summer tourism resources exhibits a double-peak characteristic, with concentrations in the mid- and high-latitude and high-altitude regions. Second, the most influential destinations in China based on the composite index were Guiyang, Qingdao, Harbin, and Dalian. These findings can helpful for people who are planning their summer vacations, as well as tourism managers who benefit from such increases in the number of tourists.

Solar thermal technical information guide

NASA Astrophysics Data System (ADS)

1985-05-01

This guide is designed to help investigators search for information in the solar thermal technology field. The information ranges from history and technology basics to the latest in research and develoment. It is written to help several audiences, including engineers and scientists who may be unfamiliar with a particular aspect of solar thermal energy, university researchers who are interested in the field, manufacturers needing to learn more about specific topics, and librarians who provide information to their clientele. The guide is divided into ten chapters, with Chapters 1 to 8 providing background on solar thermal energy development (including its history and current status) by topic. Within each topic, an overview is provided with references to relevant publications or information sources. Chapters 9 and 10 contain directories listing research centers and major technical information sources, respectively.

Micro-satellites thermal control—concepts and components

NASA Astrophysics Data System (ADS)

Baturkin, Volodymyr

2005-01-01

The main idea of this paper is to present the survey of current tendencies in micro-satellites thermal control concepts that can be rational and useful for posterior missions due to intensive expansion of satellites of such type. For this purpose, the available references and lessons learned by the National Technical University of Ukraine during the elaboration of thermal control hardware for micro-satellites Magion 4, 5, BIRD and autonomous thermal control systems for interplanetary missions VEGA, PHOBOS have been used. The main parameters taken into consideration for analysis are the satellite sizes, mass, power consumption, orbit parameters, altitude control peculiarities and thermal control description. It was defined that passive thermal control concepts are widely used, excepting autonomous temperature regulation for sensitive components such as batteries, high-precision optics, and some types of sensors. The practical means for realization of passive thermal control design as multi-layer insulation, optical coatings, heat conductive elements, gaskets are briefly described.

Novel Functionally Graded Thermal Barrier Coatings in Coal-Fired Power Plant Turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jing

This project presents a detailed investigation of a novel functionally graded coating material, pyrochlore oxide, for thermal barrier coating (TBC) in gas turbines used in coal-fired power plants. Thermal barrier coatings are refractory materials deposited on gas turbine components, which provide thermal protection for metallic components at operating conditions. The ultimate goal of this research is to develop a manufacturing process to produce the novel low thermal conductivity and high thermal stability pyrochlore oxide based coatings with improved high-temperature durability. The current standard TBC, yttria stabilized zirconia (YSZ), has service temperatures limited to <1200°C, due to sintering and phase transitionmore » at higher temperatures. In contrast, pyrochlore oxide, e.g., lanthanum zirconate (La 2Zr 2O 7, LZ), has demonstrated lower thermal conductivity and better thermal stability, which are crucial to high temperature applications, such as gas turbines used in coal-fired power plants. Indiana University – Purdue University Indianapolis (IUPUI) has collaborated with Praxair Surface Technologies (PST), and Changwon National University in South Korea to perform the proposed research. The research findings are critical to the extension of current TBCs to a broader range of high-temperature materials and applications. Several tasks were originally proposed and accomplished, with additional new opportunities identified during the course of the project. In this report, a description of the project tasks, the main findings and conclusions are given. A list of publications and presentations resulted from this research is listed in the Appendix at the end of the report.« less

Thermal to Visible Face Recognition

DTIC Science & Technology

2012-04-01

Thermal to Visible Face Recognition Jonghyun Choi†, Shuowen Hu‡, S. Susan Young‡ and Larry S. Davis† †University of Maryland, College Park, MD ‡U.S...Bourlai et al.7 Further author information: (Send correspondence to Jonghyun Choi) Jonghyun Choi: E-mail: jhchoi@umd.edu, Telephone: 1 301 335 3866 This

Cosmology and the early universe

NASA Astrophysics Data System (ADS)

Joshi, Abhigna

2017-01-01

In the beginning the universe was in a hot dense state nearly 13.8 billion years ago. The thermal history of the universe was traced back to an era when the temperature was about 1012K. At this early time, the universe was filled with particles-mostly photons and leptons- whose interactions are hopefully weak enough to allow this medium to be treated as a more or less ideal gas. However, if we look back a little further, into the first 0.0001 second of cosmic history when the temperature was above 1012K. At such temperatures, there will be present in thermal equilibrium copious numbers of strongly interacting particles-mostly masons and baryons-with a mean interparticle distance less than a Compton wavelength. These particles will be in a state of continual mutual interaction, and cannot reasonably be expected to obey any simple equation of state. The inflationary epoch lasted from 10-36seconds after the Big Bang to sometime between 10-33and 10-32seconds. Matter and energy created in this time. Right after that space expanded exponentially with enormous rate of 74.3 +/-2.1Km per second per Mpc. Undergraduate student and researcher of the string theory, quantum gravity, cosmology and quantum biology.

Reheating of the Universe as holographic thermalization

NASA Astrophysics Data System (ADS)

Kawai, Shinsuke; Nakayama, Yu

2016-08-01

Assuming gauge/gravity correspondence we study reheating of the Universe using its holographic dual. Inflaton decay and thermalisation of the decay products correspond to collapse of a spherical shell and formation of a blackhole in the dual anti-de Sitter (AdS) spacetime. The reheating temperature is computed as the Hawking temperature of the developed blackhole probed by a dynamical boundary, and is determined by the inflaton energy density and the AdS radius, with corrections from the dynamics of the shell collapse. For given initial energy density of the inflaton field the holographic model typically gives lower reheating temperature than the instant reheating scenario, while it is shown to be safely within phenomenological bounds.

Thermal coupon testing of Load-Bearing Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; Hurd, J.

2014-01-01

Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

Analysis of Thermal Comfort in an Intelligent Building

NASA Astrophysics Data System (ADS)

Majewski, Grzegorz; Telejko, Marek; Orman, Łukasz J.

2017-06-01

Analysis of thermal comfort in the ENERGIS Building, an intelligent building in the campus of the Kielce University of Technology, Poland is the focus of this paper. For this purpose, air temperature, air relative humidity, air flow rate and carbon dioxide concentration were measured and the mean radiant temperature was determined. Thermal sensations of the students occupying the rooms of the building were evaluated with the use of a questionnaire. The students used a seven-point scale of thermal comfort. The microclimate measurement results were used to determine the Predicted Mean Vote and the Predicted Percentage Dissatisfied indices.

Advanced Metal-Hydrides-Based Thermal Battery: A New Generation of High Density Thermal Battery Based on Advanced Metal Hydrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

HEATS Project: The University of Utah is developing a compact hot-and-cold thermal battery using advanced metal hydrides that could offer efficient climate control system for EVs. The team’s innovative designs of heating and cooling systems for EVs with high energy density, low-cost thermal batteries could significantly reduce the weight and eliminate the space constraint in automobiles. The thermal battery can be charged by plugging it into an electrical outlet while charging the electric battery and it produces heat and cold through a heat exchanger when discharging. The ultimate goal of the project is a climate-controlling thermal battery that can lastmore » up to 5,000 charge and discharge cycles while substantially increasing the driving range of EVs, thus reducing the drain on electric batteries.« less

Reheating of the Universe as holographic thermalization

DOE PAGES

Kawai, Shinsuke; Nakayama, Yu

2016-06-14

Here, assuming gauge/gravity correspondence we study reheating of the Universe using its holographic dual. Inflaton decay and thermalisation of the decay products correspond to collapse of a spherical shell and formation of a blackhole in the dual anti-de Sitter (AdS) spacetime. The reheating temperature is computed as the Hawking temperature of the developed blackhole probed by a dynamical boundary, and is determined by the inflaton energy density and the AdS radius, with corrections from the dynamics of the shell collapse. For given initial energy density of the inflaton field the holographic model gives significantly lower reheating temperature than the instantmore » reheating scenario, while it is shown to be safely within phenomenological bounds.« less

Reheating of the Universe as holographic thermalization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawai, Shinsuke; Nakayama, Yu

Here, assuming gauge/gravity correspondence we study reheating of the Universe using its holographic dual. Inflaton decay and thermalisation of the decay products correspond to collapse of a spherical shell and formation of a blackhole in the dual anti-de Sitter (AdS) spacetime. The reheating temperature is computed as the Hawking temperature of the developed blackhole probed by a dynamical boundary, and is determined by the inflaton energy density and the AdS radius, with corrections from the dynamics of the shell collapse. For given initial energy density of the inflaton field the holographic model gives significantly lower reheating temperature than the instantmore » reheating scenario, while it is shown to be safely within phenomenological bounds.« less

Influence of degradation conditions on dentin bonding durability of three universal adhesives.

PubMed

Sai, Keiichi; Shimamura, Yutaka; Takamizawa, Toshiki; Tsujimoto, Akimasa; Imai, Arisa; Endo, Hajime; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2016-11-01

This study aims to determine dentin bonding durability of universal adhesives using shear bond strength (SBS) tests under various degradation conditions. G-Premio Bond (GP, GC), Scotchbond Universal (SU, 3M ESPE) and All Bond Universal (AB, Bisco) were compared with conventional two-step self-etch adhesive Clearfil SE Bond (SE, Kuraray Noritake Dental). Bonded specimens were divided into three groups of ten, and SBSs with bovine dentin were determined after the following treatments: 1) Storage in distilled water at 37°C for 24h followed by 3000, 10,000, 20,000 or 30,000 thermal cycles (TC group), 2) Storage in distilled water at 37°C for 3 months, 6 months or 1year (water storage, WS group) and 3) Storage in distilled water at 37°C for 24h (control). SE bonded specimens showed significantly higher SBSs than universal adhesives, regardless of TC or storage periods, although AB specimens showed significantly increased SBSs after 30,000 thermal cycles. In comparisons of universal adhesives under control and degradation conditions, SBS was only reduced in SU after 1year of WS. Following exposure of various adhesive systems to degradation conditions of thermal cycling and long term storage, SBS values of adhesive systems varied primarily with degradation period. Although universal adhesives have lower SBSs than the two-step self-etch adhesive SE, the present data indicate that the dentin bonding durability of universal adhesives in self-etch mode is sufficient for clinical use. Copyright © 2016 Elsevier Ltd. All rights reserved.

Twelfth Thermal and Fluids Analysis Workshop

NASA Technical Reports Server (NTRS)

Majumdar, Alok (Compiler)

2002-01-01

The Twelfth Thermal and Fluids Analysis Workshop (TFAWS 01) was held at the Bevill Center, The University of Alabama in Huntsville, Huntsville, Alabama, September 10-14, 2001. The theme for the hands-on training workshop and conference was "Engineering Excellence and Advances in the New Millenium." Forty-five technical papers were presented in four sessions: (1) Thermal Spacecraft/Payloads, (2) Thermal Propulsion/Vehicles, (3) Interdisciplinary Papers, and (4) Fluids Papers. Thirty-nine papers were published in these proceedings. The remaining six papers were not available in electronic format at the time of publication. In addition to the technical papers, there were (a) nine hands-on classes on thermal and flow analyses software, (b) thirteen short courses and product overview lectures, (c) five keynote lectures and, (d) panel discussions consisting of eight presentations. The workshop resulted in participation of 195 persons representing NASA Centers, Government agencies, aerospace industries, academia, software providers, and private corporations.

Thermalizing Sterile Neutrino Dark Matter.

PubMed

Hansen, Rasmus S L; Vogl, Stefan

2017-12-22

Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

Thermalizing Sterile Neutrino Dark Matter

NASA Astrophysics Data System (ADS)

Hansen, Rasmus S. L.; Vogl, Stefan

2017-12-01

Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

Thermal Conductivity of Metallic Uranium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hin, Celine

This project has developed a modeling and simulation approaches to predict the thermal conductivity of metallic fuels and their alloys. We focus on two methods. The first method has been developed by the team at the University of Wisconsin Madison. They developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab-initio and semi-empirical physics-based models to maximize the strengths of both techniques. The second method has been developed by the team at Virginia Tech. This approach consists of a determining the thermal conductivity using only ab-initio methods without any fitting parameters. Bothmore » methods were complementary. The models incorporated both phonon and electron contributions. Good agreement with experimental data over a wide temperature range were found. The models also provided insight into the different physical factors that govern the thermal conductivity under different temperatures. The models were general enough to incorporate more complex effects like additional alloying species, defects, transmutation products and noble gas bubbles to predict the behavior of complex metallic alloys like U-alloy fuel systems under burnup. 3 Introduction Thermal conductivity is an important thermal physical property affecting the performance and efficiency of metallic fuels [1]. Some experimental measurement of thermal conductivity and its correlation with composition and temperature from empirical fitting are available for U, Zr and their alloys with Pu and other minor actinides. However, as reviewed in by Kim, Cho and Sohn [2], due to the difficulty in doing experiments on actinide materials, thermal conductivities of metallic fuels have only been measured at limited alloy compositions and temperatures, some of them even being negative and unphysical. Furthermore, the correlations developed so far are empirical in nature and may not be accurate when used for prediction at conditions far from

Theory of turbulent thermal convection

NASA Astrophysics Data System (ADS)

Lohse, Detlef

2002-03-01

We review our universal theory for the scaling of the Nusselt number and the Reynolds number as functions of the Rayleigh number and the Prandtl number in turbulent thermal convection (Siegfried Grossmann and Detlef Lohse, J. Fluid Mech. 407, 27 (2000); Phys. Rev. Lett. 86, 3316 (2001)). This theory is based on a decomposition of the energy dissipation and the thermal dissipation into a bulk and a boundary layer contribution. We will in particular focus on the behavior for large Prandtl numbers and on the scaling behavior of the Reynolds number for which new experimental results have been obtained recently. We will also address the chaotic switching of the large scale wind of turbulence.

Universe opacity and CMB

NASA Astrophysics Data System (ADS)

Vavryčuk, Václav

2018-07-01

A cosmological model, in which the cosmic microwave background (CMB) is a thermal radiation of intergalactic dust instead of a relic radiation of the big bang, is revived and revisited. The model suggests that a virtually transparent local Universe becomes considerably opaque at redshifts z > 2-3. Such opacity is hardly to be detected in the Type Ia supernova data, but confirmed using quasar data. The opacity steeply increases with redshift because of a high proper density of intergalactic dust in the previous epochs. The temperature of intergalactic dust increases as (1 + z) and exactly compensates the change of wavelengths due to redshift, so that the dust radiation looks apparently like the radiation of the blackbody with a single temperature. The predicted dust temperature is TD = 2.776 K, which differs from the CMB temperature by 1.9 per cent only, and the predicted ratio between the total CMB and extragalactic background light (EBL) intensities is 13.4 which is close to 12.5 obtained from observations. The CMB temperature fluctuations are caused by EBL fluctuations produced by galaxy clusters and voids in the Universe. The polarization anomalies of the CMB correlated with temperature anisotropies are caused by the polarized thermal emission of needle-shaped conducting dust grains aligned by large-scale magnetic fields around clusters and voids. A strong decline of the luminosity density for z > 4 is interpreted as the result of high opacity of the Universe rather than of a decline of the global stellar mass density at high redshifts.

Universe opacity and CMB

NASA Astrophysics Data System (ADS)

Vavryčuk, Václav

2018-04-01

A cosmological model, in which the cosmic microwave background (CMB) is a thermal radiation of intergalactic dust instead of a relic radiation of the Big Bang, is revived and revisited. The model suggests that a virtually transparent local Universe becomes considerably opaque at redshifts z > 2 - 3. Such opacity is hardly to be detected in the Type Ia supernova data, but confirmed using quasar data. The opacity steeply increases with redshift because of a high proper density of intergalactic dust in the previous epochs. The temperature of intergalactic dust increases as (1 + z) and exactly compensates the change of wavelengths due to redshift, so that the dust radiation looks apparently like the radiation of the blackbody with a single temperature. The predicted dust temperature is TD = 2.776 K, which differs from the CMB temperature by 1.9% only, and the predicted ratio between the total CMB and EBL intensities is 13.4 which is close to 12.5 obtained from observations. The CMB temperature fluctuations are caused by EBL fluctuations produced by galaxy clusters and voids in the Universe. The polarization anomalies of the CMB correlated with temperature anisotropies are caused by the polarized thermal emission of needle-shaped conducting dust grains aligned by large-scale magnetic fields around clusters and voids. A strong decline of the luminosity density for z > 4 is interpreted as the result of high opacity of the Universe rather than of a decline of the global stellar mass density at high redshifts.

The Tenth Thermal and Fluids Analysis Workshop

NASA Technical Reports Server (NTRS)

Majumdar, Alok (Compiler); McConnaughey, Paul (Technical Monitor)

2001-01-01

The Tenth Thermal arid Fluids Analysis Workshop (TFAWS 99) was held at the Bevill Center, University of Alabama in Huntsville, Huntsville, Alabama, September 13-17, 1999. The theme for the hands-on training workshop and conference was "Tools and Techniques Contributing to Engineering Excellence". Forty-seven technical papers were presented in four sessions. The sessions were: (1) Thermal Spacecraft/Payloads, (2) Thermal Propulsion/Vehicles, (3) Interdisciplinary Paper, and (4) Fluids Paper. Forty papers were published in these proceedings. The remaining seven papers were not available in electronic format at the time of publication. In addition to the technical papers, there were (a) nine hands-on classes on thermal and flow analyses software, (b) twelve short courses, (c) thirteen product overview lectures, and (d) three keynote lectures. The workshop resulted in participation of 171 persons representing NASA Centers, Government agencies, aerospace industries, academia, software providers, and private corporations.

Local thermal energy as a structural indicator in glasses.

PubMed

Zylberg, Jacques; Lerner, Edan; Bar-Sinai, Yohai; Bouchbinder, Eran

2017-07-11

Identifying heterogeneous structures in glasses-such as localized soft spots-and understanding structure-dynamics relations in these systems remain major scientific challenges. Here, we derive an exact expression for the local thermal energy of interacting particles (the mean local potential energy change caused by thermal fluctuations) in glassy systems by a systematic low-temperature expansion. We show that the local thermal energy can attain anomalously large values, inversely related to the degree of softness of localized structures in a glass, determined by a coupling between internal stresses-an intrinsic signature of glassy frustration-anharmonicity and low-frequency vibrational modes. These anomalously large values follow a fat-tailed distribution, with a universal exponent related to the recently observed universal [Formula: see text] density of states of quasilocalized low-frequency vibrational modes. When the spatial thermal energy field-a "softness field"-is considered, this power law tail manifests itself by highly localized spots, which are significantly softer than their surroundings. These soft spots are shown to be susceptible to plastic rearrangements under external driving forces, having predictive powers that surpass those of the normal modes-based approach. These results offer a general, system/model-independent, physical/observable-based approach to identify structural properties of quiescent glasses and relate them to glassy dynamics.

Phoenix Lowered into Thermal Vacuum Chamber

NASA Technical Reports Server (NTRS)

2007-01-01

NASA's Phoenix Mars Lander was lowered into a thermal vacuum chamber at Lockheed Martin Space Systems, Denver, in December 2006.

The spacecraft was folded in its aeroshell and underwent environmental testing that simulated the extreme conditions the spacecraft will see during its nine-and-a-half-month cruse to Mars.

The Phoenix mission is led by Principal Investigator Peter H. Smith of the University of Arizona, Tucson, with project management at NASA's Jet Propulsion Laboratory and development partnership with Lockheed Martin Space Systems. International contributions for Phoenix are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen, and the Max Planck Institute in Germany. JPL is a division of the California Institute of Technology in Pasadena.

Construction of a Thermal Vacuum Chamber for Environment Test of Triple CubeSat Mission TRIO-CINEMA

NASA Astrophysics Data System (ADS)

Jeon, Jeheon; Lee, Seongwhan; Yoon, Seyoung; Seon, Jongho; Jin, Ho; Lee, Donghun; Lin, Robert P.

2013-12-01

TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA) is a CubeSat with 3.14 kg in weight and 3-U (10 × 10 × 30 cm) in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultrahigh vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.

Joint Removal Implications : Thermal Analysis and Life-Cycle Cost

DOT National Transportation Integrated Search

2018-04-01

Deck joints are causing significant bridge deterioration and maintenance problems for Departments of Transportation (DOTs). Colorado State University researchers partnered with the Colorado DOT to analyze the effects of temperature change and thermal...

Mock-up experiment at Birmingham University for BNCT project of Osaka University--Neutron flux measurement with gold foil.

PubMed

Tamaki, S; Sakai, M; Yoshihashi, S; Manabe, M; Zushi, N; Murata, I; Hoashi, E; Kato, I; Kuri, S; Oshiro, S; Nagasaki, M; Horiike, H

2015-12-01

Mock-up experiment for development of accelerator based neutron source for Osaka University BNCT project was carried out at Birmingham University, UK. In this paper, spatial distribution of neutron flux intensity was evaluated by foil activation method. Validity of the design code system was confirmed by comparing measured gold foil activities with calculations. As a result, it was found that the epi-thermal neutron beam was well collimated by our neutron moderator assembly. Also, the design accuracy was evaluated to have less than 20% error. Copyright © 2015 Elsevier Ltd. All rights reserved.

Unstable Hadrons in Hot Hadron Gas in Laboratory and in the Early Universe

NASA Astrophysics Data System (ADS)

Kuznetsova, Inga; Rafelski, Johann

2011-04-01

We study kinetic master equations for reactions involving the formation and the natural decay of unstable particles in a thermal expanding hadronic gas in the laboratory and in the early Universe. We consider here for the first time the role of the decay channel of one (hadron resonance) into two daughter particles, and also by token of detailed balance the inverse process, fusion of two (thermal) particles into one. We obtain the thermal invariant reaction rate using as an input the free space (vacuum) decay time and show the medium quantum effects on π+π<->ρ reaction relaxation time. As another laboratory example we describe the K+K<->φ process in thermal expanding hadronic gas in heavy ions collisions. A particularly interesting application of our formalism is the 0̂<->γ+γ process in the early Universe. We also explore the fate of charged pions and the muon freeze-out in the Universe. Another interesting field of application of our formalism is the study of short lived hadronic resonances, which are in general not able to reach yield equilibrium. We study the evolution of hadron resonances in small drops of QGP and use the insight gained to generalize the dynamics to QED effects as well.

Universal Scaling Laws in the Dynamics of a Homogeneous Unitary Bose Gas

NASA Astrophysics Data System (ADS)

Eigen, Christoph; Glidden, Jake A. P.; Lopes, Raphael; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P.

2017-12-01

We study the dynamics of an initially degenerate homogeneous Bose gas after an interaction quench to the unitary regime at a magnetic Feshbach resonance. As the cloud decays and heats, it exhibits a crossover from degenerate- to thermal-gas behavior, both of which are characterized by universal scaling laws linking the particle-loss rate to the total atom number N . In the degenerate and thermal regimes, the per-particle loss rate is ∝N2 /3 and N26 /9, respectively. The crossover occurs at a universal kinetic energy per particle and at a universal time after the quench, in units of energy and time set by the gas density. By slowly sweeping the magnetic field away from the resonance and creating a mixture of atoms and molecules, we also map out the dynamics of correlations in the unitary gas, which display a universal temporal scaling with the gas density, and reach a steady state while the gas is still degenerate.

Universal Scaling Laws in the Dynamics of a Homogeneous Unitary Bose Gas.

PubMed

Eigen, Christoph; Glidden, Jake A P; Lopes, Raphael; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P

2017-12-22

We study the dynamics of an initially degenerate homogeneous Bose gas after an interaction quench to the unitary regime at a magnetic Feshbach resonance. As the cloud decays and heats, it exhibits a crossover from degenerate- to thermal-gas behavior, both of which are characterized by universal scaling laws linking the particle-loss rate to the total atom number N. In the degenerate and thermal regimes, the per-particle loss rate is ∝N^{2/3} and N^{26/9}, respectively. The crossover occurs at a universal kinetic energy per particle and at a universal time after the quench, in units of energy and time set by the gas density. By slowly sweeping the magnetic field away from the resonance and creating a mixture of atoms and molecules, we also map out the dynamics of correlations in the unitary gas, which display a universal temporal scaling with the gas density, and reach a steady state while the gas is still degenerate.

Thermal design and validation of radiation detector for the ChubuSat-2 micro-satellite with high-thermal-conductive graphite sheets

NASA Astrophysics Data System (ADS)

Park, Daeil; Miyata, Kikuko; Nagano, Hosei

2017-07-01

This paper describes thermal design of the radiation detector (RD) for the ChubuSat-2 with the use of high-thermal-conductive materials. ChubuSat-2 satellite is a 50-kg-class micro-satellite joint development with Nagoya University and aerospace companies. The main mission equipment of ChubuSat-2 is a RD to observe neutrons and gamma rays. However, the thermal design of the RD encounters a serious problem, such as no heater for RD and electric circuit alignment constrain. To solve this issue, the RD needs a new thermal design and thermal control for successful space missions. This paper proposes high-thermal-conductive graphite sheets to be used as a flexible radiator fin for the RD. Before the fabrication of the device, the optimal thickness and surface area for the flexible radiator fin were determined by thermal analysis. Consequently, the surface area of flexible radiator fin was determined to be 8.6×104 mm2. To verify the effects of the flexible radiator fin, we constructed a verification model and analyzed the temperature distributions in the RD. Also, the thermal vacuum test was performed using a thermal vacuum chamber, which was evacuated at a pressure of around 10-4 Pa, and its internal temperature was cooled at -80 °C by using a refrigerant. As a result, it has been demonstrated that the flexible radiator fin is effective. And the thermal vacuum test results are presented good correlation with the analysis results.

Entropy generation method to quantify thermal comfort

NASA Technical Reports Server (NTRS)

Boregowda, S. C.; Tiwari, S. N.; Chaturvedi, S. K.

2001-01-01

The present paper presents a thermodynamic approach to assess the quality of human-thermal environment interaction and quantify thermal comfort. The approach involves development of entropy generation term by applying second law of thermodynamics to the combined human-environment system. The entropy generation term combines both human thermal physiological responses and thermal environmental variables to provide an objective measure of thermal comfort. The original concepts and definitions form the basis for establishing the mathematical relationship between thermal comfort and entropy generation term. As a result of logic and deterministic approach, an Objective Thermal Comfort Index (OTCI) is defined and established as a function of entropy generation. In order to verify the entropy-based thermal comfort model, human thermal physiological responses due to changes in ambient conditions are simulated using a well established and validated human thermal model developed at the Institute of Environmental Research of Kansas State University (KSU). The finite element based KSU human thermal computer model is being utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal responses to different environmental conditions. The output from the simulation, which include human thermal responses and input data consisting of environmental conditions are fed into the thermal comfort model. Continuous monitoring of thermal comfort in comfortable and extreme environmental conditions is demonstrated. The Objective Thermal Comfort values obtained from the entropy-based model are validated against regression based Predicted Mean Vote (PMV) values. Using the corresponding air temperatures and vapor pressures that were used in the computer simulation in the regression equation generates the PMV values. The preliminary results indicate that the OTCI and PMV values correlate well under ideal conditions. However, an experimental study

Entropy generation method to quantify thermal comfort.

PubMed

Boregowda, S C; Tiwari, S N; Chaturvedi, S K

2001-12-01

The present paper presents a thermodynamic approach to assess the quality of human-thermal environment interaction and quantify thermal comfort. The approach involves development of entropy generation term by applying second law of thermodynamics to the combined human-environment system. The entropy generation term combines both human thermal physiological responses and thermal environmental variables to provide an objective measure of thermal comfort. The original concepts and definitions form the basis for establishing the mathematical relationship between thermal comfort and entropy generation term. As a result of logic and deterministic approach, an Objective Thermal Comfort Index (OTCI) is defined and established as a function of entropy generation. In order to verify the entropy-based thermal comfort model, human thermal physiological responses due to changes in ambient conditions are simulated using a well established and validated human thermal model developed at the Institute of Environmental Research of Kansas State University (KSU). The finite element based KSU human thermal computer model is being utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal responses to different environmental conditions. The output from the simulation, which include human thermal responses and input data consisting of environmental conditions are fed into the thermal comfort model. Continuous monitoring of thermal comfort in comfortable and extreme environmental conditions is demonstrated. The Objective Thermal Comfort values obtained from the entropy-based model are validated against regression based Predicted Mean Vote (PMV) values. Using the corresponding air temperatures and vapor pressures that were used in the computer simulation in the regression equation generates the PMV values. The preliminary results indicate that the OTCI and PMV values correlate well under ideal conditions. However, an experimental study

Electrically Driven Thermal Management: Flight Validation, Experiment Development, Future Technologies

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

2018-01-01

Electrically Driven Thermal Management is an active research and technology development initiative incorporating ISS technology flight demonstrations (STP-H5), development of Microgravity Science Glovebox (MSG) flight experiment, and laboratory-based investigations of electrically based thermal management techniques. The program targets integrated thermal management for future generations of RF electronics and power electronic devices. This presentation reviews four program elements: i.) results from the Electrohydrodynamic (EHD) Long Term Flight Demonstration launched in February 2017 ii.) development of the Electrically Driven Liquid Film Boiling Experiment iii.) two University based research efforts iv.) development of Oscillating Heat Pipe evaluation at Goddard Space Flight Center.

Surface effects on the thermal conductivity of silicon nanowires

NASA Astrophysics Data System (ADS)

Li, Hai-Peng; Zhang, Rui-Qin

2018-03-01

Thermal transport in silicon nanowires (SiNWs) has recently attracted considerable attention due to their potential applications in energy harvesting and generation and thermal management. The adjustment of the thermal conductivity of SiNWs through surface effects is a topic worthy of focus. In this paper, we briefly review the recent progress made in this field through theoretical calculations and experiments. We come to the conclusion that surface engineering methods are feasible and effective methods for adjusting nanoscale thermal transport and may foster further advancements in this field. Project supported by the National Natural Science Foundation ofChina (Grant No. 11504418), China Scholarship Council (Grant No. 201706425053), Basic Research Program in Shenzhen, China (Grant No. JCYJ20160229165210666), and the Fundamental Research Funds for the Central Universities of China (Grant No. 2015XKMS075).

Numerical Large Deviation Analysis of the Eigenstate Thermalization Hypothesis

NASA Astrophysics Data System (ADS)

Yoshizawa, Toru; Iyoda, Eiki; Sagawa, Takahiro

2018-05-01

A plausible mechanism of thermalization in isolated quantum systems is based on the strong version of the eigenstate thermalization hypothesis (ETH), which states that all the energy eigenstates in the microcanonical energy shell have thermal properties. We numerically investigate the ETH by focusing on the large deviation property, which directly evaluates the ratio of athermal energy eigenstates in the energy shell. As a consequence, we have systematically confirmed that the strong ETH is indeed true even for near-integrable systems. Furthermore, we found that the finite-size scaling of the ratio of athermal eigenstates is a double exponential for nonintegrable systems. Our result illuminates the universal behavior of quantum chaos, and suggests that a large deviation analysis would serve as a powerful method to investigate thermalization in the presence of the large finite-size effect.

Local thermal energy as a structural indicator in glasses

NASA Astrophysics Data System (ADS)

Zylberg, Jacques; Lerner, Edan; Bar-Sinai, Yohai; Bouchbinder, Eran

2017-07-01

Identifying heterogeneous structures in glasses—such as localized soft spots—and understanding structure-dynamics relations in these systems remain major scientific challenges. Here, we derive an exact expression for the local thermal energy of interacting particles (the mean local potential energy change caused by thermal fluctuations) in glassy systems by a systematic low-temperature expansion. We show that the local thermal energy can attain anomalously large values, inversely related to the degree of softness of localized structures in a glass, determined by a coupling between internal stresses—an intrinsic signature of glassy frustration—anharmonicity and low-frequency vibrational modes. These anomalously large values follow a fat-tailed distribution, with a universal exponent related to the recently observed universal ω4ω4 density of states of quasilocalized low-frequency vibrational modes. When the spatial thermal energy field—a “softness field”—is considered, this power law tail manifests itself by highly localized spots, which are significantly softer than their surroundings. These soft spots are shown to be susceptible to plastic rearrangements under external driving forces, having predictive powers that surpass those of the normal modes-based approach. These results offer a general, system/model-independent, physical/observable-based approach to identify structural properties of quiescent glasses and relate them to glassy dynamics.

Thermal lensing in ocular media

NASA Astrophysics Data System (ADS)

Vincelette, Rebecca Lee

2009-12-01

This research was a collaborative effort between the Air Force Research Laboratory (AFRL) and the University of Texas to examine the laser-tissue interaction of thermal lensing induced by continuous-wave, CW, near-infrared, NIR, laser radiation in the eye and its influence on the formation of a retinal lesion from said radiation. CW NIR laser radiation can lead to a thermal lesion induced on the retina given sufficient power and exposure duration as related to three basic parameters; the percent of transmitted energy to, the optical absorption of, and the size of the laser-beam created at the retina. Thermal lensing is a well-known phenomenon arising from the optical absorption, and subsequent temperature rise, along the path of the propagating beam through a medium. Thermal lensing causes the laser-beam profile delivered to the retina to be time dependent. Analysis of a dual-beam, multidimensional, high-frame rate, confocal imaging system in an artificial eye determined the rate of thermal lensing in aqueous media exposed to 1110, 1130, 1150 and 1318-nm wavelengths was related to the power density created along the optical axis and linear absorption coefficient of the medium. An adaptive optics imaging system was used to record the aberrations induced by the thermal lens at the retina in an artificial eye during steady-state. Though the laser-beam profiles changed over the exposure time, the CW NIR retinal damage thresholds between 1110--1319-nm were determined to follow conventional fitting algorithms which neglected thermal lensing. A first-order mathematical model of thermal lensing was developed by conjoining an ABCD beam propagation method, Beer's law of attenuation, and a solution to the heat-equation with respect to radial diffusion. The model predicted that thermal lensing would be strongest for small (< 4-mm) 1/e2 laser-beam diameters input at the corneal plane and weakly transmitted wavelengths where less than 5% of the energy is delivered to the retina

Monitoring Local Strain in a Thermal Barrier Coating System Under Thermal Mechanical Gas Turbine Operating Conditions

NASA Astrophysics Data System (ADS)

Manero, Albert; Sofronsky, Stephen; Knipe, Kevin; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M.; Raghavan, Seetha; Bartsch, Marion

2015-07-01

Advances in aircraft and land-based turbine engines have been increasing the extreme loading conditions on traditional engine components and have incited the need for improved performance with the use of protective coatings. These protective coatings shield the load-bearing super alloy blades from the high-temperature combustion gases by creating a thermal gradient over their thickness. This addition extends the life and performance of blades. A more complete understanding of the behavior, failure mechanics, and life expectancy for turbine blades and their coatings is needed to enhance and validate simulation models. As new thermal-barrier-coated materials and deposition methods are developed, strides to effectively test, evaluate, and prepare the technology for industry deployment are of paramount interest. Coupling the experience and expertise of researchers at the University of Central Florida, The German Aerospace Center, and Cleveland State University with the world-class synchrotron x-ray beam at the Advanced Photon Source in Argonne National Laboratory, the synergistic collaboration has yielded previously unseen measurements to look inside the coating layer system for in situ strain measurements during representative service loading. These findings quantify the in situ strain response on multilayer thermal barrier coatings and shed light on the elastic and nonelastic properties of the layers and the role of mechanical load and internal cooling variations on the response. The article discusses the experimental configuration and development of equipment to perform in situ strain measurements on multilayer thin coatings and provides an overview of the achievements thus far.

Thermal-Structures and Materials Testing Laboratory

NASA Technical Reports Server (NTRS)

Teate, Anthony A.

1997-01-01

Since its inception and successful implementation in 1997 at James Madison University, the Thermal Structures and Materials Testing Laboratory (T-SaMTL) funded by the NASA Langley Research Center is evolving into one of the University's premier and exemplary efforts to increase minority representation in the sciences and mathematics. Serving ten (10) students and faculty directly and almost fifty (50) students indirectly, T-SAMTL, through its recruitment efforts, workshops, mentoring program, tutorial services and its research and computational laboratories has marked the completion of the first year with support from NASA totaling $ 100,000. Beginning as an innovative academic research and mentoring program for underrepresented minority science and mathematics students, the program now boasts a constituency which consists of 50% graduating seniors in the spring of 1998 with 50% planning to go to graduate school. The program's intent is to increase the number of underrepresented minorities who receive doctoral degrees in the sciences by initiating an academically enriched research program aimed at strengthening the academic and self actualization skills of undergraduate students with the potential to pursue doctoral study in the sciences. The program provides financial assistance, academic enrichment, and professional and personal development support for minority students who demonstrate the potential and strong desire to pursue careers in the sciences and mathematics. James Madison University was awarded the first $100,000, in April 1997, by The NASA Langley Research Center for establishment and support of its Thermal Structures and Materials Testing

Scaling universality at the dynamic vortex Mott transition

NASA Astrophysics Data System (ADS)

Lankhorst, M.; Poccia, N.; Stehno, M. P.; Galda, A.; Barman, H.; Coneri, F.; Hilgenkamp, H.; Brinkman, A.; Golubov, A. A.; Tripathi, V.; Baturina, T. I.; Vinokur, V. M.

2018-01-01

The cleanest way to observe a dynamic Mott insulator-to-metal transition (DMT) without the interference from disorder and other effects inherent to electronic and atomic systems, is to employ the vortex Mott states formed by superconducting vortices in a regular array of pinning sites. Here, we report the critical behavior of the vortex system as it crosses the DMT line, driven by either current or temperature. We find universal scaling with respect to both, expressed by the same scaling function and characterized by a single critical exponent coinciding with the exponent for the thermodynamic Mott transition. We develop a theory for the DMT based on the parity reflection-time reversal (P T ) symmetry breaking formalism and find that the nonequilibrium-induced Mott transition has the same critical behavior as the thermal Mott transition. Our findings demonstrate the existence of physical systems in which the effect of a nonequilibrium drive is to generate an effective temperature and hence the transition belonging in the thermal universality class.

Thermal design and test results for SUNLITE ultra-stable reference cavity

NASA Technical Reports Server (NTRS)

Amundsen, Ruth M.

1991-01-01

SUNLITE (Stanford University-NASA Laser In-Space Technology Experiment) is a space-based experiment which uses a reference cavity to provide a stable frequency reference for a terahertz laser oscillator. Thermal stability of the cavity is a key factor in attaining a stable narrow-linewidth laser beam. The mount which is used to support and align the cavity will provide thermal isolation from the environment. The baseline requirement for thermal stability of the cavity is 0.025 C/min, but the design is directed toward achieving stability well beyond this requirement to improve the science data gained. A prototype of the cavity mount was fabricated and tested to characterize the thermal performance. The thermal vacuum test involved stable high-resolution temperature measurements and stable baseplate temperature control over long durations. Based on test data, the cavity mount design satisfies the severe requirement for the cavity thermal stability.

Product-sum universality and Rushbrooke inequality in explosive percolation

NASA Astrophysics Data System (ADS)

Sabbir, M. M. H.; Hassan, M. K.

2018-05-01

We study explosive percolation (EP) on an Erdös-Rényi network for product rule (PR) and sum rule (SR). Initially, it was claimed that EP describes discontinuous phase transition; now it is well accepted as a probabilistic model for thermal continuous phase transition (CPT). However, no model for CPT is complete unless we know how to relate its observable quantities with those of thermal CPT. To this end, we define entropy and specific heat, redefine susceptibility, and show that they behave exactly like their thermal counterparts. We obtain the critical exponents ν ,α ,β , and γ numerically and find that both PR and SR belong to the same universality class and obey Rushbrooke inequality.

Synchronous infrared imaging methods to characterize thermal properties of materials

NASA Astrophysics Data System (ADS)

Ouyang, Zhong

1999-11-01

A fundamental thermal property of a material is its thermal conductivity. The current state-of-the art for measurement of thermal conductivity is inadequate, especially in the case of composite materials. This dissertation addresses the need for a rapid and accurate measurement of thermal conductivity that can provide values for three orthogonal directions in a single measurement. The theoretical approach is based on three-dimensional thermal wave propagation and scattering treatments that have been developed earlier at Wayne State University. The experimental approach makes use of a state-of-the-art focal-plane-array infrared camera, which is used to follow the time- and spatial-progression of the planar heat pulse on both surfaces of the slab. The method has been used to determine the thermal diffusivity of six pure elemental single crystal materials (Cu, Ti, Bi, Al, Ag, Pb). The results are in good agreement (better than 1%) with the diffusivities calculated from the handbook. The diffusivities of some alloys and unidirectional graphite-fiber-reinforced-polymer composite also are determined by this method. As a byproduct of one of the experimental approaches measuring the IR radiation from the heated surface, direct evidence is obtained for the presence of a thermal wave "echo". The theory and confirming measurements in this dissertation represent its first clear confirmation. A second experimental method which is studied in this dissertation, and which may be used to characterize thermal properties of materials, is that of lock-in thermal wave imaging. In this technique, pioneered earlier at Wayne State University, a periodic heat source is applied to the surface of the material, and synchronous, phase-sensitive detection of the IR radiation from that surface is used to determine the effects of thermal wave propagation to subsurface features, and the effects of reflected thermal waves from those features on the observed IR radiation from the surface. The

Application of Universal Thermal Climate Index (UTCI) for assessment of occupational heat stress in open-pit mines.

PubMed

Nassiri, Parvin; Monazzam, Mohammad Reza; Golbabaei, Farideh; Dehghan, Somayeh Farhang; Rafieepour, Athena; Mortezapour, Ali Reza; Asghari, Mehdi

2017-10-07

The purpose of this article is to examine the applicability of Universal Thermal Climate Index (UTCI) index as an innovative index for evaluating of occupational heat stress in outdoor environments. 175 workers of 12 open-pit mines in Tehran, Iran were selected for this research study. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, relative humidity and air flow rate were measured; then UTCI, wet-bulb globe temperature (WBGT) and heat stress index (HSI) indices were calculated. Simultaneously, physiological parameters including heart rate, oral temperature, tympanic temperature and skin temperature of workers were measured. UTCI and WBGT are positively significantly correlated with all environmental parameters (p<0.03), except for air velocity (r<-0.39; p>0.05). Moreover, a strong significant relationship was found between UTCI and WBGT (r=0.95; p<0.001). The significant positive correlations exist between physiological parameters including oral temperature, tympanic and skin temperatures and heart rate and both the UTCI and WBGT indices (p<0.029). The highest correlation coefficient has been found between the UTCI and physiological parameters. Due to the low humidity and air velocity (~<1 m/s) in understudied mines, UTCI index appears to be appropriate to assess the occupational heat stress in these outdoor workplaces.

Comment on "Ratchet universality in the presence of thermal noise".

PubMed

Quintero, Niurka R; Alvarez-Nodarse, Renato; Cuesta, José A

2013-12-01

A recent paper [P. J. Martínez and R. Chacón, Phys. Rev. E 87, 062114 (2013)] presents numerical simulations on a system exhibiting directed ratchet transport of a driven overdamped Brownian particle subjected to a spatially periodic, symmetric potential. The authors claim that their simulations prove the existence of a universal waveform of the external force that optimally enhances directed transport, hence confirming the validity of a previous conjecture put forth by one of them in the limit of vanishing noise intensity. With minor corrections due to noise, the conjecture holds even in the presence of noise, according to the authors. On the basis of their results the authors claim that all previous theories, which predict a different optimal force waveform, are incorrect. In this Comment we provide sufficient numerical evidence showing that there is no such universal force waveform and that the evidence obtained by the authors otherwise is due to their particular choice of parameters. Our simulations also suggest that previous theories correctly predict the shape of the optimal waveform within their validity regime, namely, when the forcing is weak. On the contrary, the aforementioned conjecture does not hold.

A thermal biosensor based on enzyme reaction.

PubMed

Zheng, Yi-Hua; Hua, Tse-Chao; Xu, Fei

2005-01-01

Application of the thermal biosensor as analytical tool is promising due to advantages as universal, simplicity and quick response. A novel thermal biosensor based on enzyme reaction has been developed. This biosensor is a flow injection analysis system and consists of two channels with enzyme reaction column and reference column. The reference column, which is set for eliminating the unspecific heat, is inactived on special enzyme reaction of the ingredient to be detected. The special enzyme reaction takes places in the enzyme reaction column at a constant temperature realizing by a thermoelectric thermostat. Thermal sensor based on the thermoelectric module containing 127 serial BiTe-thermocouples is used to monitor the temperature difference between two streams from the enzyme reaction column and the reference column. The analytical example for dichlorvos shows that this biosensor can be used as analytical tool in medicine and biology.

Entanglement complexity in quantum many-body dynamics, thermalization, and localization

NASA Astrophysics Data System (ADS)

Yang, Zhi-Cheng; Hamma, Alioscia; Giampaolo, Salvatore M.; Mucciolo, Eduardo R.; Chamon, Claudio

2017-07-01

Entanglement is usually quantified by von Neumann entropy, but its properties are much more complex than what can be expressed with a single number. We show that the three distinct dynamical phases known as thermalization, Anderson localization, and many-body localization are marked by different patterns of the spectrum of the reduced density matrix for a state evolved after a quantum quench. While the entanglement spectrum displays Poisson statistics for the case of Anderson localization, it displays universal Wigner-Dyson statistics for both the cases of many-body localization and thermalization, albeit the universal distribution is asymptotically reached within very different time scales in these two cases. We further show that the complexity of entanglement, revealed by the possibility of disentangling the state through a Metropolis-like algorithm, is signaled by whether the entanglement spectrum level spacing is Poisson or Wigner-Dyson distributed.

The physiological equivalent temperature - a universal index for the biometeorological assessment of the thermal environment

NASA Astrophysics Data System (ADS)

Höppe, P.

With considerably increased coverage of weather information in the news media in recent years in many countries, there is also more demand for data that are applicable and useful for everyday life. Both the perception of the thermal component of weather as well as the appropriate clothing for thermal comfort result from the integral effects of all meteorological parameters relevant for heat exchange between the body and its environment. Regulatory physiological processes can affect the relative importance of meteorological parameters, e.g. wind velocity becomes more important when the body is sweating. In order to take into account all these factors, it is necessary to use a heat-balance model of the human body. The physiological equivalent temperature (PET) is based on the Munich Energy-balance Model for Individuals (MEMI), which models the thermal conditions of the human body in a physiologically relevant way. PET is defined as the air temperature at which, in a typical indoor setting (without wind and solar radiation), the heat budget of the human body is balanced with the same core and skin temperature as under the complex outdoor conditions to be assessed. This way PET enables a layperson to compare the integral effects of complex thermal conditions outside with his or her own experience indoors. On hot summer days, for example, with direct solar irradiation the PET value may be more than 20 K higher than the air temperature, on a windy day in winter up to 15 K lower.

Hypersonic research at Stanford University

NASA Technical Reports Server (NTRS)

Candler, Graham; Maccormack, Robert

1988-01-01

The status of the hypersonic research program at Stanford University is discussed and recent results are highlighted. The main areas of interest in the program are the numerical simulation of radiating, reacting and thermally excited flows, the investigation and numerical solution of hypersonic shock wave physics, the extension of the continuum fluid dynamic equations to the transition regime between continuum and free-molecule flow, and the development of novel numerical algorithms for efficient particulate simulations of flowfields.

Heat Transfer Issues in Thin-Film Thermal Radiation Detectors

NASA Technical Reports Server (NTRS)

Barry, Mamadou Y.

1999-01-01

The Thermal Radiation Group at Virginia Polytechnic Institute and State University has been working closely with scientists and engineers at NASA's Langley Research Center to develop accurate analytical and numerical models suitable for designing next generation thin-film thermal radiation detectors for earth radiation budget measurement applications. The current study provides an analytical model of the notional thermal radiation detector that takes into account thermal transport phenomena, such as the contact resistance between the layers of the detector, and is suitable for use in parameter estimation. It was found that the responsivity of the detector can increase significantly due to the presence of contact resistance between the layers of the detector. Also presented is the effect of doping the thermal impedance layer of the detector with conducting particles in order to electrically link the two junctions of the detector. It was found that the responsivity and the time response of the doped detector decrease significantly in this case. The corresponding decrease of the electrical resistance of the doped thermal impedance layer is not sufficient to significantly improve the electrical performance of the detector. Finally, the "roughness effect" is shown to be unable to explain the decrease in the thermal conductivity often reported for thin-film layers.

University of Wisconsin-Madison Participation in the International Water-Vapor Project (IHOP)

NASA Technical Reports Server (NTRS)

Knuteson, Robert; Antonelli, Paolo; Best, Fred; Dutcher, Steve; Feltz, Wayne; Revercomb, Henry

2003-01-01

This is the final report for NASA grant NAG-1-02057/University of Wisconsin-Madison/Dr. Henry E Revercomb, PI. This grant supported the University of Wisconsin-Madison participation in the International Water-Vapor Project (IHOP) experiment in May-June 2002. The upwelling thermal infrared emission from the surface and atmosphere over the U. S. Southern Great Plains was obtained from the NASA DC-8 with the Scanning High-resolution Interferometer Sounder (S-HIS) instrument, Analysis of the S-HIS radiances were used to obtain atmospheric temperature profiles below the aircraft. In a complementary manner, the downwelling thermal infrared emission at the surface was obtained by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) instrument from a mobile research vehicle and used to profile the atmospheric boundary layer at the Homestead site. This report summarizes the observations of the S-HIS and AERI instruments during IHOP including validation against in situ observations.

P and CP violation and new thermalization scenario in heavy ion collisions

NASA Astrophysics Data System (ADS)

Zhitnitsky, Ariel R.

2011-03-01

The violation of local P and CP invariance in QCD has been a subject of intense discussions for the last couple of years as a result of very interesting ongoing results coming from RHIC. Separately, a new thermalization scenario for heavy ion collisions through the event horizon as a manifestation of the Unruh effect, has been also suggested. In this paper we argue that these two, naively unrelated phenomena, are actually two sides of the same coin as they are deeply rooted into the same fundamental physics related to some very nontrivial topological features of QCD. We formulate the universality conjecture for P and CP odd effects in heavy ion collisions analogous to the universal thermal behaviour observed in all other high energy interactions.

Comment on ``Ratchet universality in the presence of thermal noise''

NASA Astrophysics Data System (ADS)

Quintero, Niurka R.; Alvarez-Nodarse, Renato; Cuesta, José A.

2013-12-01

A recent paper [P. J. Martínez and R. Chacón, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.87.062114 87, 062114 (2013)] presents numerical simulations on a system exhibiting directed ratchet transport of a driven overdamped Brownian particle subjected to a spatially periodic, symmetric potential. The authors claim that their simulations prove the existence of a universal waveform of the external force that optimally enhances directed transport, hence confirming the validity of a previous conjecture put forth by one of them in the limit of vanishing noise intensity. With minor corrections due to noise, the conjecture holds even in the presence of noise, according to the authors. On the basis of their results the authors claim that all previous theories, which predict a different optimal force waveform, are incorrect. In this Comment we provide sufficient numerical evidence showing that there is no such universal force waveform and that the evidence obtained by the authors otherwise is due to their particular choice of parameters. Our simulations also suggest that previous theories correctly predict the shape of the optimal waveform within their validity regime, namely, when the forcing is weak. On the contrary, the aforementioned conjecture does not hold.

Non-thermal leptogenesis from the heavier Majorana neutrinos

NASA Astrophysics Data System (ADS)

Asaka, T.; Nielsen, H. B.; Takanishi, Y.

2002-12-01

We investigate a scheme for making leptogenesis by means of the /CP violating decays of the seesaw Majorana neutrinos proposed by Fukugita and Yanagida. However, in order to avoid the wash-out of the produced lepton number we propose the production of the Majorana neutrinos to occur non-thermally and sufficiently late. After this time, in consequence, the /B-L (baryon minus lepton) quantum number becomes a good ``accidental symmetry'' protecting the asymmetry produced. This non-thermal leptogenesis at late time is realized by a boson decaying into the Majorana neutrinos with a long lifetime. Suggestively this boson could correspond to a scalar field which causes the cosmic inflation, the inflaton, and thus its decay means really the reheating of the Universe. We find that this mechanism works well even if the lightest Majorana neutrinos are not produced sufficiently or not present, and the decays of the heavier seesaw Majorana neutrinos can be responsible to the baryon asymmetry in the present Universe, as we illustrate by the example of the family replicated gauge group model.

Thermal impulse response and the temperature preference of Escherichia coli

NASA Astrophysics Data System (ADS)

Ryu, William

2010-03-01

From a broad perspective, exposure to environmental temperature changes is a universal condition of living organisms. Escherichia coli is a powerful model system to study how a biochemical network measures and processes thermal information to produce adaptive changes in behavior. E. coli performs thermotaxis, directing its movements to a preferred temperature in spatial thermal gradients. How does the system perform thermotaxis? Where biologically is this analog value of thermal preference stored? Previous studies using populations of cells have shown that E.coli accumulate in spatial thermal gradients, but these experiments did not cleanly separate thermal responses from chemotactic responses. Here we have isolated the thermal behavior by studying the thermal impulse response of single, tethered cells. The motor output of cells was measured in response to small, impulsive increases in temperature, delivered by an infrared laser, over a range of ambient temperature (23 to 43 degrees C). The thermal impulse response at temperatures < 31 degrees C is similar to the chemotactic impulse response: both follow a similar time course, share the same directionality, and show biphasic characteristics. At temperatures > 31 degrees C, some cells show an inverted response, switching from warm- to cold-seeking behavior. The fraction of inverted responses increases nonlinearly with temperature, switching steeply at the preferred temperature of 37 degrees C.

PCM/wood composite to store thermal energy in passive building envelopes

NASA Astrophysics Data System (ADS)

Barreneche, C.; Vecstaudza, J.; Bajare, D.; Fernandez, A. I.

2017-10-01

The development of new materials to store thermal energy in a passive building system is a must to improve the thermal efficiency by thermal-regulating the indoor temperatures. This fact will deal with the reduction of the gap between energy supply and energy demand to achieve thermal comfort in building indoors. The aim of this work was to test properties of novel PCM/wood composite materials developed at Riga Technical University. Impregnation of PCM (phase change material) in wood increases its thermal mass and regulates temperature fluctuations during day and night. The PCM used are paraffin waxes (RT-21 and RT-27 from Rubitherm) and the wood used was black alder, the most common wood in Latvia. The PCM distribution inside wood sample has been studied as well as its thermophysical, mechanical and fire reaction properties. Developed composite materials are promising in the field of energy saving in buildings.

The Experimental Determination of Thermal Neutron Flux in the Radiochemistry Curriculum

ERIC Educational Resources Information Center

Grant, Patrick M.

1977-01-01

Describes an experiment for determining the thermal neutron flux of the light-water nuclear reactor at the University of California, Irvine. The difficulty of the activity can be varied to match the student's level of proficiency. (SL)

The Thermal Expansion Of Feldspars

NASA Astrophysics Data System (ADS)

Hovis, G. L.; Medford, A.; Conlon, M.

2009-12-01

Hovis and others (1) investigated the thermal expansion of natural and synthetic AlSi3 feldspars and demonstrated that the coefficient of thermal expansion (α) decreases significantly, and linearly, with increasing room-temperature volume (VRT). In all such feldspars, therefore, chemical expansion limits thermal expansion. The scope of this work now has been broadened to include plagioclase and Ba-K feldspar crystalline solutions. X-ray powder diffraction data have been collected between room temperature and 925 °C on six plagioclase specimens ranging in composition from anorthite to oligoclase. When combined with thermal expansion data for albite (2,3,4) a steep linear trend of α as a function of VRT emerges, reflecting how small changes in composition dramatically affect expansion behavior. The thermal expansion data for five synthetic Ba-K feldspars ranging in composition from 20 to 100 mole percent celsian, combined with data for pure K-feldspar (3,4), show α-VRT relationships similar in nature to the plagioclase series, but with a slope and intercept different from the latter. Taken as a group all Al2Si2 feldspars, including anorthite and celsian from the present study along with Sr- (5) and Pb-feldspar (6) from other workers, show very limited thermal expansion that, unlike AlSi3 feldspars, has little dependence on the divalent-ion (or M-) site occupant. This apparently is due to the necessitated alternation of Al and Si in the tetrahedral sites of these minerals (7), which in turn locks the tetrahedral framework and makes the M-site occupant nearly irrelevant to expansion behavior. Indeed, in feldspar series with coupled chemical substitution it is the change away from a 1:1 Al:Si ratio that gives feldspars greater freedom to expand. Overall, the relationships among α, chemical composition, and room-temperature volume provide useful predictive tools for estimating feldspar thermal expansion and give insight into the controls of expansion behavior in

Detecting the Curvature of de Sitter Universe with Two Entangled Atoms

NASA Astrophysics Data System (ADS)

Tian, Zehua; Wang, Jieci; Jing, Jiliang; Dragan, Andrzej

2016-10-01

Casimir-Polder interaction arises from the vacuum fluctuations of quantum field that depend on spacetime curvature and thus is spacetime-dependent. Here we show how to use the resonance Casimir-Polder interaction (RCPI) between two entangled atoms to detect spacetime curvature. We find that the RCPI of two static entangled atoms in the de Sitter-invariant vacuum depends on the de Sitter spacetime curvature relevant to the temperature felt by the static observer. It is characterized by a 1/L2 power law decay when beyond a characteristic length scale associated to the breakdown of a local inertial description of the two-atom system. However, the RCPI of the same setup embedded in a thermal bath in the Minkowski universe is temperature-independent and is always characterized by a 1/L power law decay. Therefore, although a single static atom in the de Sitter-invariant vacuum responds as if it were bathed in thermal radiation in a Minkowski universe, using the distinct difference between RCPI of two entangled atoms one can in principle distinguish these two universes.

Detecting the Curvature of de Sitter Universe with Two Entangled Atoms.

PubMed

Tian, Zehua; Wang, Jieci; Jing, Jiliang; Dragan, Andrzej

2016-10-12

Casimir-Polder interaction arises from the vacuum fluctuations of quantum field that depend on spacetime curvature and thus is spacetime-dependent. Here we show how to use the resonance Casimir-Polder interaction (RCPI) between two entangled atoms to detect spacetime curvature. We find that the RCPI of two static entangled atoms in the de Sitter-invariant vacuum depends on the de Sitter spacetime curvature relevant to the temperature felt by the static observer. It is characterized by a 1/L 2 power law decay when beyond a characteristic length scale associated to the breakdown of a local inertial description of the two-atom system. However, the RCPI of the same setup embedded in a thermal bath in the Minkowski universe is temperature-independent and is always characterized by a 1/L power law decay. Therefore, although a single static atom in the de Sitter-invariant vacuum responds as if it were bathed in thermal radiation in a Minkowski universe, using the distinct difference between RCPI of two entangled atoms one can in principle distinguish these two universes.

Detecting the Curvature of de Sitter Universe with Two Entangled Atoms

PubMed Central

Tian, Zehua; Wang, Jieci; Jing, Jiliang; Dragan, Andrzej

2016-01-01

Casimir-Polder interaction arises from the vacuum fluctuations of quantum field that depend on spacetime curvature and thus is spacetime-dependent. Here we show how to use the resonance Casimir-Polder interaction (RCPI) between two entangled atoms to detect spacetime curvature. We find that the RCPI of two static entangled atoms in the de Sitter-invariant vacuum depends on the de Sitter spacetime curvature relevant to the temperature felt by the static observer. It is characterized by a 1/L2 power law decay when beyond a characteristic length scale associated to the breakdown of a local inertial description of the two-atom system. However, the RCPI of the same setup embedded in a thermal bath in the Minkowski universe is temperature-independent and is always characterized by a 1/L power law decay. Therefore, although a single static atom in the de Sitter-invariant vacuum responds as if it were bathed in thermal radiation in a Minkowski universe, using the distinct difference between RCPI of two entangled atoms one can in principle distinguish these two universes. PMID:27731419

The Inclusion of Thermal Emissions Within the SASKTRAN Framework

NASA Astrophysics Data System (ADS)

Jensen, K. L.; Bourassa, A. E.; Lloyd, N. D.; Degenstein, D. A.

2013-12-01

The SASKTRAN radiative transfer model developed at the University of Saskatchewan has a long heritage associated with simulations of spectrally dispersed limb scattered sunlight. Recent advancements in the SASKTRAN model have allowed for the inclusion of thermal emissions, as a new source of light, originating within the atmosphere and from the ground. Within the model these thermal emissions are then subsequently propagated through the atmosphere while being scattered and absorbed in the exact same fashion as if sunlight were the source of photons. This development allows for the use of the existing and elaborate SASKTRAN infrastructure in the near infrared where scattering of sunlight and thermal emissions contribute with similar fractions to the total intensity of any atmospheric radiance measurement. This paper details the changes to the SASKTRAN model required to accurately simulate scattered thermal emissions and presents results related to the remote sensing of atmospheric constituents such as carbon dioxide, carbon monoxide and methane from satellite platforms.

Model Comparison for Electron Thermal Transport

NASA Astrophysics Data System (ADS)

Moses, Gregory; Chenhall, Jeffrey; Cao, Duc; Delettrez, Jacques

2015-11-01

Four electron thermal transport models are compared for their ability to accurately and efficiently model non-local behavior in ICF simulations. Goncharov's transport model has accurately predicted shock timing in implosion simulations but is computationally slow and limited to 1D. The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. uses multigroup diffusion to speed up the calculation. Chenhall has expanded upon the iSNB diffusion model to a higher order simplified P3 approximation and a Monte Carlo transport model, to bridge the gap between the iSNB and Goncharov models while maintaining computational efficiency. Comparisons of the above models for several test problems will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

Environmental Testing in Thermal Vacuum Chamber

NASA Technical Reports Server (NTRS)

2007-01-01

Inside a thermal vacuum at Lockheed Martin Space Systems, Denver, technicians prepare NASA's Phoenix Mars Lander for environmental testing.

The Phoenix lander was encapsulated in its aeroshell -- which included both the back shell and heat shield -- as it was subjected to extreme cold and heat in a vacuum, space-like condition. The spacecraft undergoes extensive environmental testing to confirm Phoenix will perform in the extreme conditions it will experience during its trip from Earth to Mars, during its arrival and landing, and while it works on the surface of Mars.

The Phoenix mission is led by Principal Investigator Peter H. Smith of the University of Arizona, Tucson, with project management at NASA's Jet Propulsion Laboratory and development partnership with Lockheed Martin Space Systems. International contributions for Phoenix are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen, and the Max Planck Institute in Germany. JPL is a division of the California Institute of Technology in Pasadena.

International Field Reversible Thermal Connector (RevCon) Challenge

DTIC Science & Technology

2016-07-01

Design ....................................................................... 80 Figure 74: Pulsating - heat - pipe Embedded Design Delivered by MissStateU...University MissStateU finally delivered a pulsating - heat - pipe thermal connector. However, the performance did not amaze the audiences. The size and...We also cannot observe any oscillating dynamics during heating . Figure 74: Pulsating - heat - pipe Embedded Design Delivered by MissStateU

Thermal Hardware for the Thermal Analyst

NASA Technical Reports Server (NTRS)

Steinfeld, David

2015-01-01

The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Space Flight Center (GSFC) Thermal Engineering Branch (Code 545). NCTS 21070-1. Most Thermal analysts do not have a good background into the hardware which thermally controls the spacecraft they design. SINDA and Thermal Desktop models are nice, but knowing how this applies to the actual thermal hardware (heaters, thermostats, thermistors, MLI blanketing, optical coatings, etc...) is just as important. The course will delve into the thermal hardware and their application techniques on actual spacecraft. Knowledge of how thermal hardware is used and applied will make a thermal analyst a better engineer.

Scaling universality at the dynamic vortex Mott transition

DOE PAGES

Lankhorst, M.; Poccia, N.; Stehno, M. P.; ...

2018-01-17

The cleanest way to observe a dynamic Mott insulator-to-metal transition (DMT) without the interference from disorder and other effects inherent to electronic and atomic systems, is to employ the vortex Mott states formed by superconducting vortices in a regular array of pinning sites. Here, we report the critical behavior of the vortex system as it crosses the DMT line, driven by either current or temperature. We find universal scaling with respect to both, expressed by the same scaling function and characterized by a single critical exponent coinciding with the exponent for the thermodynamic Mott transition. We develop a theory formore » the DMT based on the parity reflection-time reversal (PT) symmetry breaking formalism and find that the nonequilibrium-induced Mott transition has the same critical behavior as the thermal Mott transition. Our findings demonstrate the existence of physical systems in which the effect of a nonequilibrium drive is to generate an effective temperature and hence the transition belonging in the thermal universality class.« less

Thermal Analysis of a Finite Element Model in a Radiation Dominated Environment

NASA Technical Reports Server (NTRS)

Page, Arthur T.

2001-01-01

This paper presents a brief overview of thermal analysis, evaluating the University of Arizona mirror design, for the Next Generation Space Telescope (NGST) Pre-Phase A vehicle concept. Model building begins using Thermal Desktop(TM), by Cullimore and Ring Technologies, to import a NASTRAN bulk data file from the structural model of the mirror assembly. Using AutoCAD(R) capabilities, additional surfaces are added to simulate the thermal aspects of the problem which, for due reason, are not part of the structural model. Surfaces are then available to accept thermophysical and thermo-optical properties. Thermal Desktop(TM) calculates radiation conductors using Monte Carlo simulations. Then Thermal Desktop(TM) generates the SINDA input file having a one-to-one correspondence with the NASTRAN node and element definitions. A model is now available to evaluate the mirror design in the radiation dominated environment, conduct parametric trade studies of the thermal design, and provide temperatures to the finite element structural model.

Thermal Analysis of a Finite Element Model in a Radiation Dominated Environment

NASA Technical Reports Server (NTRS)

Page, Arhur T.

1999-01-01

This paper presents a brief overview of thermal analysis, evaluating the University of Arizona mirror design, for the Next Generation Space Telescope (NGST) Pre-Phase A vehicle concept. Model building begins using Thermal Desktop(Tm), by Cullimore and Ring Technologies, to import a NASTRAN bulk data file from the structural model of the mirror assembly. Using AutoCAD(R) capabilities, additional surfaces are added to simulate the thermal aspects of the problem which, for due reason, are not part of the structural model. Surfaces are then available to accept thermophysical and thermo-optical properties. Thermal Desktop(Tm) calculates radiation conductors using Monte Carlo simulations. Then Thermal Desktop(Tm) generates the SINDA/Fluint input file having a one-to-one correspondence with the NASTRAN node and element definitions. A model is now available to evaluate the mirror design in the radiation dominated environment conduct parametric trade studies of the thermal design, and provide temperatures to the finite element structural model.

Representation of thermal infrared imaging data in the DICOM using XML configuration files.

PubMed

Ruminski, Jacek

2007-01-01

The DICOM standard has become a widely accepted and implemented format for the exchange and storage of medical imaging data. Different imaging modalities are supported however there is not a dedicated solution for thermal infrared imaging in medicine. In this article we propose new ideas and improvements to final proposal of the new DICOM Thermal Infrared Imaging structures and services. Additionally, we designed, implemented and tested software packages for universal conversion of existing thermal imaging files to the DICOM format using XML configuration files. The proposed solution works fast and requires minimal number of user interactions. The XML configuration file enables to compose a set of attributes for any source file format of thermal imaging camera.

Thermal conductivity of the Lennard-Jones chain fluid model.

PubMed

Galliero, Guillaume; Boned, Christian

2009-12-01

Nonequilibrium molecular dynamics simulations have been performed to estimate, analyze, and correlate the thermal conductivity of a fluid composed of short Lennard-Jones chains (up to 16 segments) over a large range of thermodynamic conditions. It is shown that the dilute gas contribution to the thermal conductivity decreases when the chain length increases for a given temperature. In dense states, simulation results indicate that the residual thermal conductivity of the monomer increases strongly with density, but is weakly dependent on the temperature. Compared to the monomer value, it has been noted that the residual thermal conductivity of the chain was slightly decreasing with its length. Using these results, an empirical relation, including a contribution due to the critical enhancement, is proposed to provide an accurate estimation of the thermal conductivity of the Lennard-Jones chain fluid model (up to 16 segments) over the domain 0.8thermal conductivity values of the Lennard-Jones chain fluid model merge on the same "universal" curve when plotted as a function of the excess entropy. Furthermore, it is shown that the reduced configurational thermal conductivity of the Lennard-Jones chain fluid model is approximately proportional to the reduced excess entropy for all fluid states and all chain lengths.

Laboratory measurements of gravel thermal properties. A methodology proposal

NASA Astrophysics Data System (ADS)

Cultrera, Matteo; Peron, Fabio; Bison, Paolo; Dalla Santa, Giorgia; Bertermann, David; Muller, Johannes; Bernardi, Adriana; Galgaro, Antonio

2017-04-01

Gravel thermal properties measurements at laboratory level is quite challenging due to several technical and logistic issues, mainly connected to the sediment sizes and the variability of their mineralogical composition. The direct measurement of gravel thermal properties usually are not able to involve a representative volume of geological material, consequently the thermal measurements performed produce much dispersed results and not consistent due to the large interstitial voids and the poor physical contact with the measuring sensors. With the aim of directly provide the measurement of the gravel thermal properties, a new methodology has been developed and some results are already available on several gravel deposits samples around Europe. Indeed, a single guarded hot plate Taurus Instruments TLP 800 measured the gravel thermal properties. Some instrumental adjustments were necessary to adapt the measuring devices and to finalize the thermal measurements on gravels at the IUAV FISTEC laboratory (Environmental Technical Physics Laboratory of Venice University). This device usually provides thermal measurements according to ISO 8302, ASTM C177, EN 1946-2, EN 12664, EN 12667 and EN 12939 for building materials. A preliminary calibration has been performed comparing the outcomes obtained with the single guarded hot plate with a needle probe of a portable thermal conductivity meter (ISOMET). Standard sand (ISO 67:2009) is used as reference material. This study is provided under the Cheap-GSHPs project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 657982

Development and evaluation of a prototype concentrating solar collector with thermocline based thermal energy storage for residential thermal usage

DOE PAGES

Kumar, Vinod; Afrin, Samia; Ortega, Jesus; ...

2013-09-01

A prototype of a concentrating solar collector (CSC) receiver was designed, built, and evaluated on-sun at the University of Texas at El Paso in El Paso, TX. This prototype receiver consists of two parabolic trough-reflectors but, in principle, the design can be efficiently extended to multiple units for achieving a higher temperature throughput. Each reflector has a vacuum tube collector at the focal point of the trough. The solar collector system was combined with a single-tank thermocline thermal energy storage (TES) for off-solar thermal usage. The main goal of this study is to develop an advanced solar hot water systemmore » for most residential applications. The focus of this study is to investigate the feasibility and performance of the solar thermal system by employing the recent advancement in the TES—a thermocline based TES—system for the concentrating solar power technologies developed by the Sandia National Laboratories and National Renewable Energy Laboratories for electricity production. A CSC when combined with TES has potential to provide uninterrupted thermal energy for most residential usages. This paper presents a detailed description of prototype design and materials required. The thermal energy storage tank utilizes an insulated 170 l (45 gal) galvanized steel tank. In order to maintain thermocline in the TES tank, with hot water on top and cold water at the bottom, two plate distributors are installed in the tank. The data showed a significant enhancement in thermal energy generation. This thermocline based single tank presented a thermal energy storage potential for at least three days (with diminishing storage capacity) that test were performed. The whole prototype was made for approximately USD 355 (excludes any labor costs) and hence also has strong potential for supplying clean thermal energy in most developing countries. As a result, tests of the prototype were conducted in November 2011.« less

Thermal balneotherapy in Antsirabe-Madagascar: water analysis and its applications in an African context.

PubMed

Pedrazzini, Alessio; Delsignore, Roberto; Martelli, Alessandra; Tocco, Silvio; Vaienti, Enrico; Ceccarelli, Francesco; Pogliacomi, Francesco

2016-04-15

The Orthopaedic Rehabilitation Centre of Madagascar can be found in the city of Antsirabe. The health care facility is equipped with 2 thermal sources of bicarbonate water used for post-operative rehabilitation and for the ailment of chronic degenerative illnesses. The aim of this study, which derives from the cooperation between the School of Specialization in Thermal Therapy of the University of Parma and Antsirabe Orthopaedic Hospital, is to analyze the real properties of thermal waters utilized in this centre and to do an overview of its possible applications in this particular African context.

An empirical analysis of thermal protective performance of fabrics used in protective clothing.

PubMed

Mandal, Sumit; Song, Guowen

2014-10-01

Fabric-based protective clothing is widely used for occupational safety of firefighters/industrial workers. The aim of this paper is to study thermal protective performance provided by fabric systems and to propose an effective model for predicting the thermal protective performance under various thermal exposures. Different fabric systems that are commonly used to manufacture thermal protective clothing were selected. Laboratory simulations of the various thermal exposures were created to evaluate the protective performance of the selected fabric systems in terms of time required to generate second-degree burns. Through the characterization of selected fabric systems in a particular thermal exposure, various factors affecting the performances were statistically analyzed. The key factors for a particular thermal exposure were recognized based on the t-test analysis. Using these key factors, the performance predictive multiple linear regression and artificial neural network (ANN) models were developed and compared. The identified best-fit ANN models provide a basic tool to study thermal protective performance of a fabric. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Fibonacci family of dynamical universality classes.

PubMed

Popkov, Vladislav; Schadschneider, Andreas; Schmidt, Johannes; Schütz, Gunter M

2015-10-13

Universality is a well-established central concept of equilibrium physics. However, in systems far away from equilibrium, a deeper understanding of its underlying principles is still lacking. Up to now, a few classes have been identified. Besides the diffusive universality class with dynamical exponent [Formula: see text], another prominent example is the superdiffusive Kardar-Parisi-Zhang (KPZ) class with [Formula: see text]. It appears, e.g., in low-dimensional dynamical phenomena far from thermal equilibrium that exhibit some conservation law. Here we show that both classes are only part of an infinite discrete family of nonequilibrium universality classes. Remarkably, their dynamical exponents [Formula: see text] are given by ratios of neighboring Fibonacci numbers, starting with either [Formula: see text] (if a KPZ mode exist) or [Formula: see text] (if a diffusive mode is present). If neither a diffusive nor a KPZ mode is present, all dynamical modes have the Golden Mean [Formula: see text] as dynamical exponent. The universal scaling functions of these Fibonacci modes are asymmetric Lévy distributions that are completely fixed by the macroscopic current density relation and compressibility matrix of the system and hence accessible to experimental measurement.

Fibonacci family of dynamical universality classes

PubMed Central

Popkov, Vladislav; Schadschneider, Andreas; Schmidt, Johannes; Schütz, Gunter M.

2015-01-01

Universality is a well-established central concept of equilibrium physics. However, in systems far away from equilibrium, a deeper understanding of its underlying principles is still lacking. Up to now, a few classes have been identified. Besides the diffusive universality class with dynamical exponent z=2, another prominent example is the superdiffusive Kardar−Parisi−Zhang (KPZ) class with z=3/2. It appears, e.g., in low-dimensional dynamical phenomena far from thermal equilibrium that exhibit some conservation law. Here we show that both classes are only part of an infinite discrete family of nonequilibrium universality classes. Remarkably, their dynamical exponents zα are given by ratios of neighboring Fibonacci numbers, starting with either z1=3/2 (if a KPZ mode exist) or z1=2 (if a diffusive mode is present). If neither a diffusive nor a KPZ mode is present, all dynamical modes have the Golden Mean z=(1+5)/2 as dynamical exponent. The universal scaling functions of these Fibonacci modes are asymmetric Lévy distributions that are completely fixed by the macroscopic current density relation and compressibility matrix of the system and hence accessible to experimental measurement. PMID:26424449

The Lockheed alternate partial polarizer universal filter

NASA Technical Reports Server (NTRS)

Title, A. M.

1976-01-01

A tunable birefringent filter using an alternate partial polarizer design has been built. The filter has a transmission of 38% in polarized light. Its full width at half maximum is .09A at 5500A. It is tunable from 4500 to 8500A by means of stepping motor actuated rotating half wave plates and polarizers. Wave length commands and thermal compensation commands are generated by a PPD 11/10 minicomputer. The alternate partial polarizer universal filter is compared with the universal birefringent filter and the design techniques, construction methods, and filter performance are discussed in some detail. Based on the experience of this filter some conclusions regarding the future of birefringent filters are elaborated.

Cosmological perturbations in the entangled inflationary universe

NASA Astrophysics Data System (ADS)

Robles-Pérez, Salvador J.

2018-03-01

In this paper, the model of a multiverse made up of universes that are created in entangled pairs that conserve the total momentum conjugated to the scale factor is presented. For the background spacetime, assumed is a Friedmann-Robertson-Walker metric with a scalar field with mass m minimally coupled to gravity. For the fields that propagate in the entangled spacetimes, the perturbations of the spacetime and the scalar field, whose quantum states become entangled too, are considered. They turn out to be in a quasithermal state, and the corresponding thermodynamical magnitudes are computed. Three observables are expected to be caused by the creation of the universes in entangled pairs: a modification of the Friedmann equation because of the entanglement of the spacetimes, a modification of the effective value of the potential of the scalar field by the backreaction of the perturbation modes, and a modification of the spectrum of fluctuations because the thermal distribution is induced by the entanglement of the partner universes. The later would be a distinctive feature of the creation of universes in entangled pairs.

Spectrum Tunable Quantum Dot-In-A-Well Infrared Detector Arrays for Thermal Imaging

DTIC Science & Technology

2008-09-01

Spectrum tunable quantum dot-in-a- well infrared detector arrays for thermal imaging Jonathan R. Andrews1, Sergio R. Restaino1, Scott W. Teare2...Materials at the University of New Mexico has been investigating quantum dot and quantum well detectors for thermal infrared imaging applications...SEP 2008 2. REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE Spectrum tunable quantum dot-in-a- well infrared

Predicting the ash behavior during biomass combustion in FBC conditions by combining advanced fuel analyses with thermodynamic multicomponent equilibrium calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skrifvars, B.J.; Blomquist, J.P.; Hupa, M.

1998-12-31

Previous work at Aabo Akademi University has focused on identification and quantification of various sintering mechanisms which are relevant for problematic ash behavior during biomass combustion in fluidized bed combustion conditions, and on multi-component multi-phase thermodynamic phase equilibrium calculations of ash chemistry in these conditions. In both areas new information has been developed and useful modeling capabilities have been created. Based on the previous work, the authors now present a novel approach of using a combination of an advanced fuel analysis method and thermodynamic phase equilibrium calculations to predict the chemical and thermal behavior of the ash when firing biomass.more » Four different fuels [coal, forest residues, wood chips, and a mixture of forest residue and wood chips] were analyzed using the chemical fractionation analysis technique. Based on the results from these analyses, the authors formed two different ash fractions, (1) one fine sized fraction consisting of those elements found in the water and weak acid leach, and (2) a coarse ash particle fraction consisting of those elements found in the strong acid leach and non-leachable rest. The small sized ash fraction was then assumed to be carried up with the flue gases and consequently formed the base for any ash related problems in the flue gas channel. This fraction was therefore analyzed on its chemical and thermal behavior using multi-component multi-phase equilibrium calculations, by which the composition and the melting behavior was estimated as a function of the temperature. The amount of melt, which has earlier been found to be strongly related to problematic ash behavior, was finally expressed as a function of the temperature for the fraction. The coarse fraction was treated separately. Here the authors estimate the composition only. The paper discusses the results and their relevance to full scale combustion.« less

NASA Goddard Thermal Technology Overview 2018

NASA Technical Reports Server (NTRS)

Butler, Dan; Swanson, Ted

2018-01-01

This presentation summarizes the current plans and efforts at NASA/Goddard to develop new thermal control technology for anticipated future missions. It will also address some of the programmatic developments currently underway at NASA, especially with respect to the NASA Technology Development Program. The effects of the recently submitted NASA budget will also be addressed. While funding for basic technology development is still tight, significant efforts are being made in direct support of flight programs. Thermal technology Implementation on current flight programs will be reviewed, and the recent push for Cube-sat mission development will also be addressed. Many of these technologies also have broad applicability to DOD, DOE, and commercial programs. Partnerships have been developed with the Air Force, Navy, and various universities to promote technology development. In addition, technology development activities supported by internal research and development (IRAD) program and the Small Business Innovative Research (SBIR) program are reviewed in this presentation. Specific technologies addressed include; two-phase systems applications and issues on NASA missions, latest developments of thermal control coatings, Atomic Layer Deposition (ALD), Micro-scale Heat Transfer, and various other research activities.

Black hole formation in a contracting universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quintin, Jerome; Brandenberger, Robert H., E-mail: jquintin@physics.mcgill.ca, E-mail: rhb@hep.physics.mcgill.ca

We study the evolution of cosmological perturbations in a contracting universe. We aim to determine under which conditions density perturbations grow to form large inhomogeneities and collapse into black holes. Our method consists in solving the cosmological perturbation equations in complete generality for a hydrodynamical fluid. We then describe the evolution of the fluctuations over the different length scales of interest and as a function of the equation of state for the fluid, and we explore two different types of initial conditions: quantum vacuum and thermal fluctuations. We also derive a general requirement for black hole collapse on sub-Hubble scales,more » and we use the Press-Schechter formalism to describe the black hole formation probability. For a fluid with a small sound speed (e.g., dust), we find that both quantum and thermal initial fluctuations grow in a contracting universe, and the largest inhomogeneities that first collapse into black holes are of Hubble size and the collapse occurs well before reaching the Planck scale. For a radiation-dominated fluid, we find that no black hole can form before reaching the Planck scale. In the context of matter bounce cosmology, it thus appears that only models in which a radiation-dominated era begins early in the cosmological evolution are robust against the formation of black holes. Yet, the formation of black holes might be an interesting feature for other models. We comment on a number of possible alternative early universe scenarios that could take advantage of this feature.« less

Bond durability of universal adhesive to bovine enamel using self-etch mode.

PubMed

Suzuki, Soshi; Takamizawa, Toshiki; Imai, Arisa; Tsujimoto, Akimasa; Sai, Keiichi; Takimoto, Masayuki; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2018-04-01

The purpose of this study was to examine the enamel bond durability of universal adhesives in the self-etch mode under 2-year water storage and thermal cycling conditions. Three commercially available universal adhesives and a gold standard two-step self-etch adhesive were used. Ten specimens of bovine enamel were prepared per test group, and shear bond strength (SBS) was measured to determine the bonding durability after thermal cycling (TC) or long-term water storage (WS). The bonded specimens were divided into three groups: (1) specimens subjected to TC, where the bonded specimens were stored in 37 °C distilled water for 24 h before being subjected to 3000, 10,000, 20,000 or 30,000 TC; (2) specimens stored in 37 °C distilled water for 3 months, 6 months, 1 year or 2 year; and (3) specimens stored in 37 °C distilled water for 24 h, serving as a baseline. The two-step self-etch adhesive showed significantly higher SBS than the universal adhesives tested, regardless of the type of degradation method. All universal adhesives showed no significant enamel SBS reductions in TC and WS, when compared to baseline and the other degradation conditions. Compared to the bond strengths obtained with the two-step self-etch adhesive, significantly lower bond strengths were obtained with universal adhesives. However, the enamel bond durability of universal adhesives was relatively stable under both degradation conditions tested. The present data indicate that the enamel bond durability of universal adhesives in the self-etch mode might be sufficient for clinical use.

Thermal structures and materials for high-speed flight; Collection of Papers of the 1st Thermal Structures Conference, University of Virginia, Charlottesville, Nov. 13-15, 1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thornton, E.A.

1992-01-01

The present conference discusses aerobrake-maneuver vehicle aerothermodynamics, aerothermal issues in the structural design of high speed vehicles, laser surface-alloying of superlight metals with ceramic surfaces, high-temperature Al alloys for supersonic and hypersonic vehicles, advanced metallics for high temperature airframes, novel materials for engine applications, and the development status of computational methods for high temperature structural design. Also discussed are a transient thermal-structural analysis using adaptive unstructured remeshing and mesh movement, the FEM thermoviscoplastic analysis of aerospace structures, hot-structures testing techniques, a thermal-structural analysis of a carbon-carbon/refractory metal heat pipe-cooled leading edge, dynamic effects in thermoviscoplastic structures, microlevel thermal effects inmore » metal-matrix composites (MMCs), thermomechanical effects in the plasma spray manufacture of MMC monotapes, and intelligent HIP processing. Most of the presentations at this conference were abstracted previously (see A91-16027 to A91-16047).« less

Irradiation and Thermal Annealing Effects in Amorphous Magnetic Alloys.

NASA Astrophysics Data System (ADS)

Fisher, David G.

thermal annealed samples. The results suggest the as-quenched state is not the ideal amorphous state. Structural relaxation resulting from either particle-irradiation or appropriate thermal annealing gives the alloys a more ideally amorphous state. References. ('(1))W. T. Franz, Ph.D. Dissertation, University of Delaware, August 1981. ('(2))T. A. Donnelly, Ph.d. Dissertation, University of Delaware, June 1982.

Thermalized axion inflation: Natural and monomial inflation with small r

NASA Astrophysics Data System (ADS)

Ferreira, Ricardo Z.; Notari, Alessio

2018-03-01

A safe way to reheat the Universe, in models of natural and quadratic inflation, is through shift symmetric couplings between the inflaton ϕ and the Standard Model (SM), since they do not generate loop corrections to the potential V (ϕ ). We consider such a coupling to SM gauge fields, of the form ϕ F F ˜/f , with sub-Planckian f . In this case, gauge fields can be exponentially produced already during inflation and thermalize via interactions with charged particles, as pointed out in previous work. This can lead to a plasma of temperature T during inflation, and the thermal masses g T of the gauge bosons can equilibrate the system. In addition, inflaton perturbations δ ϕ can also have a thermal spectrum if they have sufficiently large cross sections with the plasma. In this case, inflationary predictions are strongly modified: (1) scalar perturbations are thermal, and so enhanced over the vacuum, leading to a generic way to suppress the tensor-to-scalar ratio r ; (2) the spectral index is ns-1 =η -4 ɛ . After presenting the relevant conditions for thermalization, we show that thermalized natural and monomial models of inflation agree with present observations and have r ≈10-3-10-2, which is within reach of next generation CMB experiments.

Thermality and excited state Rényi entropy in two-dimensional CFT

NASA Astrophysics Data System (ADS)

Lin, Feng-Li; Wang, Huajia; Zhang, Jia-ju

2016-11-01

We evaluate one-interval Rényi entropy and entanglement entropy for the excited states of two-dimensional conformal field theory (CFT) on a cylinder, and examine their differences from the ones for the thermal state. We assume the interval to be short so that we can use operator product expansion (OPE) of twist operators to calculate Rényi entropy in terms of sum of one-point functions of OPE blocks. We find that the entanglement entropy for highly excited state and thermal state behave the same way after appropriate identification of the conformal weight of the state with the temperature. However, there exists no such universal identification for the Rényi entropy in the short-interval expansion. Therefore, the highly excited state does not look thermal when comparing its Rényi entropy to the thermal state one. As the Rényi entropy captures the higher moments of the reduced density matrix but the entanglement entropy only the average, our results imply that the emergence of thermality depends on how refined we look into the entanglement structure of the underlying pure excited state.

Evaluating CFRP-Masonry Bond Using Thermal Imaging

NASA Astrophysics Data System (ADS)

Ross, Joseph C.

This study presents results from non-destructive testing to evaluate the degradation of the CFRP-masonry bond using thermal imaging. The goal of the research was to identify locations where there was evidence of bond deterioration that could subsequently be verified through destructive pull-off testing. Four full-scale masonry walls were built outdoors at the University of South Florida in 1995 to evaluate the effectiveness of CFRP for repairing settlement damage. Two of the settlement-damaged walls were repaired using single layer, commercially available unidirectional CFRP systems that used Tonen (wall 3) and Henkel (wall 2) epoxies. These two walls were the subject of this investigation. Before non-destructive tests were initiated, historical site data on temperature, humidity and rainfall variation was compiled. Over seventeen years, the walls experienced ambient temperatures as high as 98°F and as low as 25°F. The average rainfall in Tampa is about 34 inches and the annual average high humidity is around 87%. Because of the high temperature and humidity, the CFRP-masonry bond was exposed to a particularly aggressive environment. Three types of thermal evaluation were carried out: thermocouple monitoring and both passive (solar) and active (localized heating) infrared thermal imaging. Twenty-four thermocouples were used to observe the spatial variations in temperature on the wall. Data showed that the surface temperatures of the wall are uneven with one end being hotter than the other. Measurements indicated that the wall temperatures went as high as 103°F during the week of data collection in late March and early April of 2012. In contrast, the highest ambient temperature over the same period was 92°F. The high temperature experienced by the wall is below the glass transition temperature for the epoxies, which ranges from 140°F to 180°F. A FLIR Tau 320 thermal imaging camera was used to identify localized de-bonding. Solar radiation heated the walls and

Universal Controller for Spacecraft Mechanisms

NASA Technical Reports Server (NTRS)

Levanas, Greg; McCarthy, Thomas; Hunter, Don; Buchanan, Christine; Johnson, Michael; Cozy, Raymond; Morgan, Albert; Tran, Hung

2006-01-01

An electronic control unit has been fabricated and tested that can be replicated as a universal interface between the electronic infrastructure of a spacecraft and a brushless-motor (or other electromechanical actuator) driven mechanism that performs a specific mechanical function within the overall spacecraft system. The unit includes interfaces to a variety of spacecraft sensors, power outputs, and has selectable actuator control parameters making the assembly a mechanism controller. Several control topologies are selectable and reconfigurable at any time. This allows the same actuator to perform different functions during the mission life of the spacecraft. The unit includes complementary metal oxide/semiconductor electronic components on a circuit board of a type called rigid flex (signifying flexible printed wiring along with a rigid substrate). The rigid flex board is folded to make the unit fit into a housing on the back of a motor. The assembly has redundant critical interfaces, allowing the controller to perform time-critical operations when no human interface with the hardware is possible. The controller is designed to function over a wide temperature range without the need for thermal control, including withstanding significant thermal cycling, making it usable in nearly all environments that spacecraft or landers will endure. A prototype has withstood 1,500 thermal cycles between 120 and +85 C without significant deterioration of its packaging or electronic function. Because there is no need for thermal control and the unit is addressed through a serial bus interface, the cabling and other system hardware are substantially reduced in quantity and complexity, with corresponding reductions in overall spacecraft mass and cost.

Thermal conductivity of zirconia thermal barrier coatings

NASA Technical Reports Server (NTRS)

Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

1995-01-01

Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor description (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard power or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increase upon being exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicates that if these coatings reach a temperature above

Thermal conductivity of zirconia thermal barrier coatings

NASA Technical Reports Server (NTRS)

Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

1995-01-01

Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor deposition (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard powder or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increases upon exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as-fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicate that if these coatings reach a temperature above 1100 C

Polarization of the Sunyaev-Zel'dovich effect: relativistic imprint of thermal and non-thermal plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emritte, Mohammad Shehzad; Colafrancesco, Sergio; Marchegiani, Paolo, E-mail: Sergio.Colafrancesco@wits.ac.za, E-mail: emrittes@yahoo.com, E-mail: Paolo.Marchegiani@wits.ac.za

2016-07-01

Inverse Compton (IC) scattering of the anisotropic CMB fluctuations off cosmic electron plasmas generates a polarization of the associated Sunyaev-Zel'dovich (SZ) effect. The polarized SZ effect has important applications in cosmology and in astrophysics of galaxy clusters. However, this signal has been studied so far mostly in the non-relativistic regime which is valid only in the very low electron temperature limit for a thermal electron population and, as such, has limited astrophysical applications. Partial attempts to extend this calculation to the IC scattering of a thermal electron plasma in the relativistic regime have been done but these cannot be appliedmore » to a more general or mildly relativistic electron distribution. In this paper we derive a general form of the SZ effect polarization that is valid in the full relativistic approach for both thermal and non-thermal electron plasmas, as well as for a generic combination of various electron population which can be co-spatially distributed in the environments of galaxy clusters or radiogalaxy lobes. We derive the spectral shape of the Stokes parameters induced by the IC scattering of every CMB multipole for both thermal and non-thermal electron populations, focussing in particular on the CMB quadrupole and octupole that provide the largest detectable signals in cosmic structures (like galaxy clusters). We found that the CMB quadrupole induced Stoke parameter Q is always positive with a maximum amplitude at a frequency ≈ 216 GHz which increases non-linearly with increasing cluster temperature. On the contrary, the CMB octupole induced Q spectrum shows a cross-over frequency which depends on the cluster electron temperature in a linear way, while it shows a non-linear dependence on the minimum momentum p {sub 1} of a non-thermal power-law spectrum as well as a linear dependence on the power-law spectral index of the non-thermal electron population. We discuss some of the possibilities to disentangle

[Chemical and Thermal Eye Burns].

PubMed

Struck, H-G

2016-11-01

Background: This review gives a therapeutic approach for the early treatment of chemical and thermal burns of the ocular surface (CTOS). Method: Based on a review of international literature, the experiences of University Hospital Aachen and Halle/Saale, Eye Clinic Cologne as well as experimental data of the research institute (An-Institut) at RWTH Aachen University are considered and discussed. Results: As the risk depends on the stage of CTOS, recommendations are given for acute treatment for different stages. Pathophysiological considerations will be discussed. Special treatment options for exceptional situations and for late phase CTOS are demonstrated. Conclusion: According to the latest data, the most important clinical recommendation for the acute phase of CTOS is the application of a suitable rinsing solution. Furthermore, anti-inflammatory treatment is of central importance. For the therapy of severe CTOS, approved and advanced surgical methods need to be applied. In this way, anti-inflammatory and tissue-protecting mechanisms are activated simultaneously. Georg Thieme Verlag KG Stuttgart · New York.

Polar Maps of Thermal and Epithermal Neutrons

NASA Technical Reports Server (NTRS)

2002-01-01

Observations by NASA's 2001 Mars Odyssey spacecraft show views of the polar regions of Mars in thermal neutrons (top) and epithermal neutrons (bottom). In these maps, deep blue indicates a low amount of neutrons, and red indicates a high amount. Thermal neutrons are sensitive to the presence of hydrogen and the presence of carbon dioxide, in this case 'dry ice' frost. The red area in the upper right map indicates that about one meter (three feet) of carbon dioxide frost covers the surface around the north pole, as it does every Mars winter in the polar regions. An enhancement of thermal neutrons close to the south pole, seen as a light green color on the upper left map, indicates the presence of residual carbon dioxide in the south polar cap, even though the annual frost dissipated from that region during southern summer. Soil enriched with hydrogen is indicated by the deep blue colors on the epithermal maps (bottom), showing a low intensity of epithermal neutrons. The deep blue areas in the polar regions are believed to contain up to 50 percent water ice in the upper one meter (three feet) of the soil. The views shown here are of measurements made during the first three months of mapping using the neutron spectrometer instrument, part of the gamma ray spectrometer instrument suite. Topographic features are superimposed on the map for geographic reference.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. Investigators at Arizona State University in Tempe, the University of Arizona in Tucson, and NASA's Johnson Space Center, Houston, operate the science instruments. The gamma-ray spectrometer was provided by the University of Arizona in collaboration with the Russian Aviation and Space Agency, which provided the high-energy neutron detector, and the Los Alamos National Laboratories, New Mexico, which provided the neutron spectrometer. Lockheed Martin Astronautics, Denver, is the prime

Thermal Investigation of Three-Dimensional GaN-on-SiC High Electron Mobility Transistors

DTIC Science & Technology

2017-07-01

AFRL-RY-WP-TR-2017-0143 THERMAL INVESTIGATION OF THREE- DIMENSIONAL GaN-on-SiC HIGH ELECTRON MOBILITY TRANSISTORS Qing Hao The University of Arizona...To) July 2017 Final 08 April 2015 – 10 April 2017 4. TITLE AND SUBTITLE THERMAL INVESTIGATION OF THREE-DIMENSIONAL GaN-on-SiC HIGH ELECTRON MOBILITY...used in many DoD applications, including integrated radio frequency (RF) amplifiers and power electronics . However, inherent inefficiencies in

Dynamic thermal environment and thermal comfort.

PubMed

Zhu, Y; Ouyang, Q; Cao, B; Zhou, X; Yu, J

2016-02-01

Research has shown that a stable thermal environment with tight temperature control cannot bring occupants more thermal comfort. Instead, such an environment will incur higher energy costs and produce greater CO2 emissions. Furthermore, this may lead to the degeneration of occupants' inherent ability to combat thermal stress, thereby weakening thermal adaptability. Measured data from many field investigations have shown that the human body has a higher acceptance to the thermal environment in free-running buildings than to that in air-conditioned buildings with similar average parameters. In naturally ventilated environments, occupants have reported superior thermal comfort votes and much greater thermal comfort temperature ranges compared to air-conditioned environments. This phenomenon is an integral part of the adaptive thermal comfort model. In addition, climate chamber experiments have proven that people prefer natural wind to mechanical wind in warm conditions; in other words, dynamic airflow can provide a superior cooling effect. However, these findings also indicate that significant questions related to thermal comfort remain unanswered. For example, what is the cause of these phenomena? How we can build a comfortable and healthy indoor environment for human beings? This article summarizes a series of research achievements in recent decades, tries to address some of these unanswered questions, and attempts to summarize certain problems for future research. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

LIEKKI -- Combustion and gasification research in Finland 1988--1998

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hupa, M.; Matinlinna, J.

1996-12-31

The objective of the Combustion and Gasification Research Program LIEKKI is to develop environmentally sound energy production techniques that are based on combustion and/or gasification. The research supports equipment manufacturers in Finland as they develop and improve their top export products, such as the fluidized bed boilers, black liquor recovery boilers, and heavy diesel power plants. The research is also heavily focused on new techniques not yet on the market, ones with higher efficiency of electricity production and, simultaneously, significantly simpler emission control systems. The most important concepts here include combustors or gasifiers based on fluidized bed technology at elevatedmore » pressures. At present the LIEKKI program includes 49 research projects and it connects some 150 scientists and research engineers in the universities and research centers of Finland. The overall annual budget of the program has been around 10 Mill. USD, co-funded by the industry and the government agency TEKES (Technology Development Centre) in Finland. The program is coordinated by Aabo Akademi University in Turku, Finland.« less

Comparison of UTCI to selected thermal indices.

PubMed

Blazejczyk, Krzysztof; Epstein, Yoram; Jendritzky, Gerd; Staiger, Henning; Tinz, Birger

2012-05-01

Over the past century more than 100 indices have been developed and used to assess bioclimatic conditions for human beings. The majority of these indices are used sporadically or for specific purposes. Some are based on generalized results of measurements (wind chill, cooling power, wet bulb temperature) and some on the empirically observed reactions of the human body to thermal stress (physiological strain, effective temperature). Those indices that are based on human heat balance considerations are referred to as "rational indices". Several simple human heat balance models are known and are used in research and practice. This paper presents a comparative analysis of the newly developed Universal Thermal Climate Index (UTCI), and some of the more prevalent thermal indices. The analysis is based on three groups of data: global data-set, synoptic datasets from Europe, and local scale data from special measurement campaigns of COST Action 730. We found the present indices to express bioclimatic conditions reasonably only under specific meteorological situations, while the UTCI represents specific climates, weather, and locations much better. Furthermore, similar to the human body, the UTCI is very sensitive to changes in ambient stimuli: temperature, solar radiation, wind and humidity. UTCI depicts temporal variability of thermal conditions better than other indices. The UTCI scale is able to express even slight differences in the intensity of meteorological stimuli.

Shocks in the Early Universe.

PubMed

Pen, Ue-Li; Turok, Neil

2016-09-23

We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

Experimental investigation of a packed bed thermal energy storage system

NASA Astrophysics Data System (ADS)

Cascetta, Mario; Cau, Giorgio; Puddu, Pierpaolo; Serra, Fabio

2015-11-01

In this work experimental investigations on a thermal energy storage system with a solid material as storage media and air as heat transfer fluid will be presented. The experimental test rig, installed at the DIMCM of the University of Cagliari, consists of a carbon steel tank filled with freely poured alumina beads that allows investigations of heat transfer phenomena in packed beds. The aim of this work is to show the influence of the operating conditions and physical parameters on thermocline formation and, in particular, the thermal behaviour of the thermal energy storage for repeated charging and discharging cycles. Better charging efficiency is obtained for lower values of mass flow rate and maximum air temperature and for increasing aspect ratio. A decreasing influence of the metal wall with continuous operation is also highlighted. In conclusion, the analysis focuses on the thermal hysteresis phenomenon, which causes degradation of the thermocline and the reduction of the energy that can be stored by the accumulator as the repeated number of cycles increases.

Temperature effects on the universal equation of state of solids

NASA Technical Reports Server (NTRS)

Vinet, P.; Ferrante, J.; Smith, J. R.; Rose, J. H.

1986-01-01

Recently it has been argued based on theoretical calculations and experimental data that there is a universal form for the equation of state of solids. This observation was restricted to the range of temperatures and pressures such that there are no phase transitions. The use of this universal relation to estimate pressure-volume relations (i.e., isotherms) required three input parameters at each fixed temperature. It is shown that for many solids the input data needed to predict high temperature thermodynamical properties can be dramatically reduced. In particular, only four numbers are needed: (1) the zero pressure (P=0) isothermal bulk modulus; (2)it P=0 pressure derivative; (3) the P=0 volume; and (4) the P=0 thermal expansion; all evaluated at a single (reference) temperature. Explicit predictions are made for the high temperature isotherms, the thermal expansion as a function of temperature, and the temperature variation of the isothermal bulk modulus and its pressure derivative. These predictions are tested using experimental data for three representative solids: gold, sodium chloride, and xenon. Good agreement between theory and experiment is found.

Temperature effects on the universal equation of state of solids

NASA Technical Reports Server (NTRS)

Vinet, Pascal; Ferrante, John; Smith, John R.; Rose, James H.

1987-01-01

Recently it has been argued based on theoretical calculations and experimental data that there is a universal form for the equation of state of solids. This observation was restricted to the range of temperatures and pressures such that there are no phase transitions. The use of this universal relation to estimate pressure-volume relations (i.e., isotherms) required three input parameters at each fixed temperature. It is shown that for many solids the input data needed to predict high temperature thermodynamical properties can be dramatically reduced. In particular, only four numbers are needed: (1) the zero pressure (P = 0) isothermal bulk modulus; (2) its P = 0 pressure derivative; (3) the P = 0 volume; and (4) the P = 0 thermal expansion; all evaluated at a single (reference) temperature. Explicit predictions are made for the high temperature isotherms, the thermal expansion as a function of temperature, and the temperature variation of the isothermal bulk modulus and its pressure derivative. These predictions are tested using experimental data for three representative solids: gold, sodium chloride, and xenon. Good agreement between theory and experiment is found.

Cosmic microwave background radiation of black hole universe

NASA Astrophysics Data System (ADS)

Zhang, T. X.

2010-11-01

Modifying slightly the big bang theory, the author has recently developed a new cosmological model called black hole universe. This new cosmological model is consistent with the Mach principle, Einsteinian general theory of relativity, and observations of the universe. The origin, structure, evolution, and expansion of the black hole universe have been presented in the recent sequence of American Astronomical Society (AAS) meetings and published recently in a scientific journal: Progress in Physics. This paper explains the observed 2.725 K cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present universe with hundred billion-trillions of solar masses. According to the black hole universe model, the observed cosmic microwave background radiation can be explained as the black body radiation of the black hole universe, which can be considered as an ideal black body. When a hot and dense star-like black hole accretes its ambient materials and merges with other black holes, it expands and cools down. A governing equation that expresses the possible thermal history of the black hole universe is derived from the Planck law of black body radiation and radiation energy conservation. The result obtained by solving the governing equation indicates that the radiation temperature of the present universe can be ˜2.725 K if the universe originated from a hot star-like black hole, and is therefore consistent with the observation of the cosmic microwave background radiation. A smaller or younger black hole universe usually cools down faster. The characteristics of the original star-like or supermassive black hole are not critical to the physical properties of the black hole universe at present, because matter and radiation are mainly from the outside space, i.e., the mother universe.

Gauge coupling unification and nonequilibrium thermal dark matter.

PubMed

Mambrini, Yann; Olive, Keith A; Quevillon, Jérémie; Zaldívar, Bryan

2013-06-14

We study a new mechanism for the production of dark matter in the Universe which does not rely on thermal equilibrium. Dark matter is populated from the thermal bath subsequent to inflationary reheating via a massive mediator whose mass is above the reheating scale T(RH). To this end, we consider models with an extra U(1) gauge symmetry broken at some intermediate scale (M(int) ≃ 10(10)-10(12) GeV). We show that not only does the model allow for gauge coupling unification (at a higher scale associated with grand unification) but it can provide a dark matter candidate which is a standard model singlet but charged under the extra U(1). The intermediate scale gauge boson(s) which are predicted in several E6/SO(10) constructions can be a natural mediator between dark matter and the thermal bath. We show that the dark matter abundance, while never having achieved thermal equilibrium, is fixed shortly after the reheating epoch by the relation T(RH)(3)/M(int)(4). As a consequence, we show that the unification of gauge couplings which determines M(int) also fixes the reheating temperature, which can be as high as T(RH) ≃ 10(11) GeV.

Nonlinear Schrödinger equation and classical-field description of thermal radiation

NASA Astrophysics Data System (ADS)

Rashkovskiy, Sergey A.

2018-03-01

It is shown that the thermal radiation can be described without quantization of energy in the framework of classical field theory using the nonlinear Schrödinger equation which is considered as a classical field equation. Planck's law for the spectral energy density of thermal radiation and the Einstein A-coefficient for spontaneous emission are derived without using the concept of the energy quanta. It is shown that the spectral energy density of thermal radiation is apparently not a universal function of frequency, as follows from the Planck's law, but depends weakly on the nature of atoms, while Planck's law is valid only as an approximation in the limit of weak excitation of atoms. Spin and relativistic effects are not considered in this paper.

Preliminary thermal architecture of the X-IFU instrument dewar

NASA Astrophysics Data System (ADS)

Charles, Ivan; Daniel, Christophe; André, Jérome; Duband, Lionel; Duval, Jean-Marc; den Hartog, Roland; Mitsuda, Kazuhisa; Shinozaki, Keisuke; van Weers, Henk; Yamasaki, Noriko Y.

2016-07-01

The ESA Athena mission will implement 2 instruments to study the hot and energetic universe. The X-ray Integral Field Unit (X-IFU) will provide spatially resolved high resolution spectroscopy. This high energy resolution of 2.5 eV at 7 keV could be achieved thanks to TES (Transition Edge Sensor) detectors that need to be cooled to very low temperature. To obtain the required 50 mK temperature level, a careful design of the cryostat and of the cooling chain including different technologies in cascade is needed. The preliminary cryogenic architecture of the X-IFU instrument that fulfils the TES detector thermal requirements is described. In particular, the thermal design of the detector focal plane assembly (FPA), that uses three temperature stages (from 2 K to 50 mK) to limit the thermal loads on the lowest temperature stage, is described. The baseline cooling chain is based on European and Japanese mechanical coolers (Stirling, Pulse tube and Joule Thomson coolers) that precool a sub Kelvin cooler made of a 3He sorption cooler coupled with a small ADR (Adiabatic Demagnetization Refrigerator). Preliminary thermal budgets of the X-IFU cryostat are presented and discussed regarding cooling chain performances.

Jet Fuel Thermal Stability

NASA Technical Reports Server (NTRS)

Taylor, W. F. (Editor)

1979-01-01

Various aspects of the thermal stability problem associated with the use of broadened-specification and nonpetroleum-derived turbine fuels are addressed. The state of the art is reviewed and the status of the research being conducted at various laboratories is presented. Discussions among representatives from universities, refineries, engine and airframe manufacturers, airlines, the Government, and others are presented along with conclusions and both broad and specific recommendations for future stability research and development. It is concluded that significant additional effort is required to cope with the fuel stability problems which will be associated with the potentially poorer quality fuels of the future such as broadened specification petroleum fuels or fuels produced from synthetic sources.

On thermal properties of hard rocks as a host environment of an underground thermal energy storage

NASA Astrophysics Data System (ADS)

Novakova, L.; Hladky, R.; Broz, M.; Novak, P.; Lachman, V.; Sosna, K.; Zaruba, J.; Metelkova, Z.; Najser, J.

2013-12-01

the studied rocks. The studies revealed thermal loading caused rapid decrease of thermal conductivity of a rock. The decrease of up to 30.6% was observed in sandstones. Reduction up to 16% was found in the granite, 12.3% in the syenite, 12.1% in the gneiss, 10.1% in the serpentinite, 8.1% in the melaphyr and 5.9 - 6.5% in ignimbites. Thermal loading initiated insignificant decrement of the thermal capacity. The capacity loss was usually less than 2%. Increasing content of water caused increase in the measured thermal characteristics. Saturated melaphyr showed 29% higher conductivity and 17.8% higher capacity comparing to the dried one. In the ignibrites there was found growth up to 23.5% in the thermal conductivity and 14.9% in the capacity, 12.1-17.6% and 4.5-5.9% in granites, 9.1% and 11.1% in the serpetinite, 7.9% and 7.9% in the gneiss and 1.2% and 3.4% in the syenite. This work was funded by the Technology Agency of the CR (TA01020348) and Ministry of Industry and trade of the CR (FR-TI3/325). Reference Sanyal, S.K., 2005. Classification of geothermal systems - a possible scheme, Proceedings, 30th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, p. 85-88.

The Universal Multizone Crystallizator (UMC) Furnace: An International Cooperative Agreement

NASA Technical Reports Server (NTRS)

Watring, D. A.; Su, C.-H.; Gillies, D.; Roosz, T.; Babcsan, N.

1996-01-01

The Universal Multizone Crystallizator (UMC) is a special apparatus for crystal growth under terrestrial and microgravity conditions. The use of twenty-five zones allows the UMC to be used for several normal freezing growth techniques. The thermal profile is electronically translated along the stationary sample by systematically reducing the power to the control zones. Elimination of mechanical translation devices increases the systems reliability while simultaneously reducing the size and weight. This paper addresses the UMC furnace design, sample cartridge and typical thermal profiles and corresponding power requirements necessary for the dynamic gradient freeze crystal growth technique. Results from physical vapor transport and traveling heater method crystal growth experiments are also discussed.

High thermal conductivity materials for thermal management applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broido, David A.; Reinecke, Thomas L.; Lindsay, Lucas R.

High thermal conductivity materials and methods of their use for thermal management applications are provided. In some embodiments, a device comprises a heat generating unit (304) and a thermally conductive unit (306, 308, 310) in thermal communication with the heat generating unit (304) for conducting heat generated by the heat generating unit (304) away from the heat generating unit (304), the thermally conductive unit (306, 308, 310) comprising a thermally conductive compound, alloy or composite thereof. The thermally conductive compound may include Boron Arsenide, Boron Antimonide, Germanium Carbide and Beryllium Selenide.

Ultraprecise thermal expansion measurements of seven low expansion materials

NASA Technical Reports Server (NTRS)

Berthold, J. W., III; Jacobs, S. F.

1976-01-01

We summarize a large number of ultraprecise thermal expansion measurements made on seven different low expansivity materials. Expansion coefficients in the -150-300 C temperature range are shown for Owens-Illinois Cer-Vit C-101, Corning ULE 7971 (titanium silicate) and fused silica 7940, Heraeus-Schott Zerodur low-expansion material and Homosil fused silica, Universal Cyclops Invar LR-35, and Simonds Saw and Steel Super Invar.

Ultraprecise thermal expansion measurements of seven low expansion materials.

PubMed

Berthold Iii, J W; Jacobs, S F

1976-10-01

We summarize a large number of ultraprecise thermal expansion measurements made on seven different low expansivity materials. Expansion coefficients in the -150-300 degrees C temperature range are shown for Owens-Illinois Cer-Vit C-101, Corning ULE 7971 (titanium silicate) and fused silica 7940, Heraeus-Schott Zerodur low-expansion material and Homosil fused silica, Universal Cyclops Invar LR-35, and Simonds Saw and Steel Super Invar.

Universality of fast quenches from the conformal perturbation theory

NASA Astrophysics Data System (ADS)

Dymarsky, Anatoly; Smolkin, Michael

2018-01-01

We consider global quantum quenches, a protocol when a continuous field theoretic system in the ground state is driven by a homogeneous time-dependent external interaction. When the typical inverse time scale of the interaction is much larger than all relevant scales except for the UV-cutoff the system's response exhibits universal scaling behavior. We provide both qualitative and quantitative explanations of this universality and argue that physics of the response during and shortly after the quench is governed by the conformal perturbation theory around the UV fixed point. We proceed to calculate the response of one and two-point correlation functions confirming and generalizing universal scalings found previously. Finally, we discuss late time behavior after the quench and argue that all local quantities will equilibrate to their thermal values specified by an excess energy acquired by the system during the quench.

EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry

NASA Astrophysics Data System (ADS)

Nozaki, Tomohiro; Gutsol, Alexander

2011-07-01

-generated reactive species are used to initiate chemical reactions at unexpectedly lower temperatures than conventional thermochemical reactions, leading to non-equilibrium product distribution or creating unconventional reaction pathways. When non-thermal plasma is combined with catalysts, a synergistic effect is frequently observed. Such unique properties of non-thermal plasma are expected to contribute excellent control over process parameters that meet the need for energy saving, environment protection, and material preservation. This special issue consists of eleven peer-reviewed papers including two invited publications. Professors Alexander Fridman and Alexander Rabinovich from Drexel University, and Dr Gutsol from the Chevron Energy Technology Company present a critical review of various industry-oriented practical plasma fuel conversion processes. Professor Richard Mallinson from University of Oklahoma describes his recent project on E85 (85%-ethanol/15%-gasoline) upgrading using non-thermal plasma and catalyst hybrid reactor, and highlights the synergistic effect on fuel conversion processes. Other papers focus on plasma/catalyst hybrid reactions for methane dry (CO2) reforming, plasma synthesis of carbon suboxide polymer from CO, the gas-to-liquid (GTL) process using a non-thermal plasma-combined micro-chemical reactor, and molecular beam characterization of plasma-generated reactive species. Much research regarding plasma catalysis is ongoing worldwide, but there is plenty of room for further development of plasma fuel processing, which could eventually provide a viable and flexible solution in future energy and material use. Finally, we would like to thank all symposium participants for their active discussion. We appreciate the sponsorship of the Division of Fuel Chemistry of the American Chemical Society. We express special thanks to the program chair of the Fuel Chemistry Division, Professor Chang-jun Liu at Tianjin University, for his dedication to the success of

Computational design and experimental validation of new thermal barrier systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Shengmin

2015-03-31

The focus of this project is on the development of a reliable and efficient ab initio based computational high temperature material design method which can be used to assist the Thermal Barrier Coating (TBC) bond-coat and top-coat design. Experimental evaluations on the new TBCs are conducted to confirm the new TBCs’ properties. Southern University is the subcontractor on this project with a focus on the computational simulation method development. We have performed ab initio density functional theory (DFT) method and molecular dynamics simulation on screening the top coats and bond coats for gas turbine thermal barrier coating design and validationmore » applications. For experimental validations, our focus is on the hot corrosion performance of different TBC systems. For example, for one of the top coatings studied, we examined the thermal stability of TaZr 2.75O 8 and confirmed it’s hot corrosion performance.« less

EAS thermal neutron detection with the PRISMA-LHAASO-16 experiment

NASA Astrophysics Data System (ADS)

Li, B.-B.; Alekseenko, V. V.; Cui, S.-w.; Chen, T.-L.; Dangzengluobu; Feng, S.-H.; Gao, Q.; Liu, Y.; Huang, Q.-C.; He, Y.-Y.; Liu, M.-Y.; Ma, X.-H.; Pozdnyakov, E. I.; Shchegolev, O. B.; Shen, F.-Z.; Stenkin, Yu. V.; Stepanov, V. I.; Yanin, Ya. V.; Yao, J.-D.; Zhou, R.

2017-12-01

EAS (extensive air shower) thermal neutron measurement gives advantages to study energy and mass composition of primary cosmic rays especially in the knee region. After the success of the PRISMA-YBJ experiment, we build a new EAS thermal neutron detection array at Tibet University, Lhasa, China (3700 m a.s.l.) in March, 2017. This prototype array so called "PRISMA-LHAASO-16" consists of 16 EAS EN-detectors ("EN" is abbreviation for electron and neutron) measuring two main EAS components: hadronic and electromagnetic ones. Different from PRISMA-YBJ, these detectors use a thin layer of a novel type of ZnS(Ag) scintillator alloyed with natural boron compound for thermal neutron capture. PRISMA-LHAASO-16 will be moved to the LHAASO site in the near future. In this paper, we introduce principle of the detection technique, deployment of the array, and the test results of the array.

Thermal storage/discharge performances of Cu-Si alloy for solar thermochemical process

NASA Astrophysics Data System (ADS)

Gokon, Nobuyuki; Yamaguchi, Tomoya; Cho, Hyun-seok; Bellan, Selvan; Hatamachi, Tsuyoshi; Kodama, Tatsuya

2017-06-01

The present authors (Niigata University, Japan) have developed a tubular reactor system using novel "double-walled" reactor/receiver tubes with carbonate molten-salt thermal storage as a phase change material (PCM) for solar reforming of natural gas and with Al-Si alloy thermal storage as a PCM for solar air receiver to produce high-temperature air. For both of the cases, the high heat capacity and large latent heat (heat of solidification) of the PCM phase circumvents the rapid temperature change of the reactor/receiver tubes at high temperatures under variable and uncontinuous characteristics of solar radiation. In this study, we examined cyclic properties of thermal storage/discharge for Cu-Si alloy in air stream in order to evaluate a potentiality of Cu-Si alloy as a PCM thermal storage material. Temperature-increasing performances of Cu-Si alloy are measured during thermal storage (or heat-charge) mode and during cooling (or heat-discharge) mode. A oxidation state of the Cu-Si alloy after the cyclic reaction was evaluated by using electron probe micro analyzer (EPMA).

An ab-initio coupled mode theory for near field radiative thermal transfer.

PubMed

Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L

2014-12-01

We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer.

Thermal barrier coatings on gas turbine blades: Chemical vapor deposition (Review)

NASA Astrophysics Data System (ADS)

Igumenov, I. K.; Aksenov, A. N.

2017-12-01

Schemes are presented for experimental setups (reactors) developed at leading scientific centers connected with the development of technologies for the deposition of coatings using the CVD method: at the Technical University of Braunschweig (Germany), the French Aerospace Research Center, the Materials Research Institute (Tohoku University, Japan) and the National Laboratory Oak Ridge (USA). Conditions and modes for obtaining the coatings with high operational parameters are considered. It is established that the formed thermal barrier coatings do not fundamentally differ in their properties (columnar microstructure, thermocyclic resistance, thermal conductivity coefficient) from standard electron-beam condensates, but the highest growth rates and the perfection of the crystal structure are achieved in the case of plasma-chemical processes and in reactors with additional laser or induction heating of a workpiece. It is shown that CVD reactors can serve as a basis for the development of rational and more advanced technologies for coating gas turbine blades that are not inferior to standard electron-beam plants in terms of the quality of produced coatings and have a much simpler and cheaper structure. The possibility of developing a new technology based on CVD processes for the formation of thermal barrier coatings with high operational parameters is discussed, including a set of requirements for industrial reactors, high-performance sources of vapor precursors, and promising new materials.

The thermal near-field: Coherence, spectroscopy, heat-transfer, and optical forces

NASA Astrophysics Data System (ADS)

Jones, Andrew C.; O'Callahan, Brian T.; Yang, Honghua U.; Raschke, Markus B.

2013-12-01

One of the most universal physical processes shared by all matter at finite temperature is the emission of thermal radiation. The experimental characterization and theoretical description of far-field black-body radiation was a cornerstone in the development of modern physics with the groundbreaking contributions from Gustav Kirchhoff and Max Planck. With its origin in thermally driven fluctuations of the charge carriers, thermal radiation reflects the resonant and non-resonant dielectric properties of media, which is the basis for far-field thermal emission spectroscopy. However, associated with the underlying fluctuating optical source polarization are fundamentally distinct spectral, spatial, resonant, and coherence properties of the evanescent thermal near-field. These properties have been recently predicted theoretically and characterized experimentally for systems with thermally excited molecular, surface plasmon polariton (SPP), and surface phonon polariton (SPhP) resonances. We review, starting with the early historical developments, the emergence of theoretical models, and the description of the thermal near-field based on the fluctuation-dissipation theory and in terms of the electromagnetic local density of states (EM-LDOS). We discuss the optical and spectroscopic characterization of distance dependence, magnitude, spectral distribution, and coherence of evanescent thermal fields. Scattering scanning near-field microscopy proved instrumental as an enabling technique for the investigations of several of these fundamental thermal near-field properties. We then discuss the role of thermal fields in nano-scale heat transfer and optical forces, and the correlation to the van der Waals, Casimir, and Casimir-Polder forces. We conclude with an outlook on the possibility of intrinsic and extrinsic resonant manipulation of optical forces, control of nano-scale radiative heat transfer with optical antennas and metamaterials, and the use of thermal infrared near

Identifying and addressing specific student difficulties in advanced thermal physics

NASA Astrophysics Data System (ADS)

Smith, Trevor I.

As part of an ongoing multi-university research study on student understanding of concepts in thermal physics at the upper division, I identified several student difficulties with topics related to heat engines (especially the Carnot cycle), as well as difficulties related to the Boltzmann factor. In an effort to address these difficulties, I developed two guided-inquiry worksheet activities (a.k.a. tutorials) for use in advanced undergraduate thermal physics courses. Both tutorials seek to improve student understanding of the utility and physical background of a particular mathematical expression. One tutorial focuses on a derivation of Carnot's theorem regarding the limit on thermodynamic efficiency, starting from the Second Law of Thermodynamics. The other tutorial helps students gain an appreciation for the origin of the Boltzmann factor and when it is applicable; focusing on the physical justification of its mathematical derivation, with emphasis on the connections between probability, multiplicity, entropy, and energy. Student understanding of the use and physical implications of Carnot's theorem and the Boltzmann factor was assessed using written surveys both before and after tutorial instruction within the advanced thermal physics courses at the University of Maine and at other institutions. Classroom tutorial sessions at the University of Maine were videotaped to allow in-depth scrutiny of student successes and failures following tutorial prompts. I also interviewed students on various topics related to the Boltzmann factor to gain a more complete picture of their understanding and inform tutorial revisions. Results from several implementations of my tutorials at the University of Maine indicate that students did not have a robust understanding of these physical principles after lectures alone, and that they gain a better understanding of relevant topics after tutorial instruction; Fisher's exact tests yield statistically significant improvement at the

Channel at Night in Thermal Infrared

NASA Technical Reports Server (NTRS)

2002-01-01

This nighttime thermal infrared image, taken by the thermal emission imaging system on NASA's 2001 Mars Odyssey spacecraft, shows differences in temperature that are due to differences in the abundance of rocks, sand and dust on the surface. Rocks remain warm at night, as seen in the warm (bright) rim of the five kilometer (three mile) diameter crater located on the right of this image.

The sinuous channel floor is cold, suggesting that it is covered by material that is more finely grained than the surrounding plains. The interior of the crater shows a great deal of thermal structure, indicating that the distribution of rocks, sand and dust varies across the floor.

The presence of rocks on the rim and inner wall indicates that this crater maintains some of its original character, despite erosion and deposition by Martian winds. Nighttime infrared images such as this one will greatly aid in mapping the physical properties of Mars' surface.

This image is centered at 2 degrees north, 0.4 degrees west, and was acquired at about 3:15 a.m. local Martian time. North is to the right of the image.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The thermal emission imaging system was provided by Arizona State University, Tempe. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Short-term changes in thermal perception associated with heatwave conditions in Melbourne, Australia

NASA Astrophysics Data System (ADS)

Lam, Cho Kwong Charlie; Gallant, Ailie J. E.; Tapper, Nigel J.

2018-05-01

Variations in human thermal perception have been described on timescales from minutes to seasons. However, the effect of weather-related thermal extremes on inter-daily changes to outdoor thermal perception has not been well characterised. This study used human thermal comfort data from an outdoor botanic garden in sub-urban Melbourne, Australia as a case study. We examined inter-daily variations in local visitors' thermal perception before (11-12 January 2014) and after (18-19 January 2014) a severe heatwave from 14 to 17 January 2014, when daily maximum temperature exceeded 41 °C for 4 consecutive days. We compared thermal comfort survey results (pre-heatwave: n = 342, post-heatwave: n = 294) with air temperature and the Universal Thermal Climate Index (UTCI) measurements. Even though the days preceding and following the heatwave had a similar range in temperature (19-25 °C) and UTCI (26-32 °C), the visitors felt cooler in the days following the heatwave (i.e. lower thermal sensation votes). In the 2 days following the heatwave, visitors also wore less clothing compared with before the heatwave. Our results show that the thermal perception of visitors changed significantly following their exposure to the heatwave, even after controlling for changes in clothing choices and the ages of survey participants. Psychological adaptation to heat (such as thermal history and expectation) might be one of the possible explanations for this inter-daily variability of local visitors' thermal perception.

Thermal neutron streaming effects and WIMS analysis of the Penn State subcritical graphite pile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feltus, M.A.; Zediak, C.S.; Jester, W.A.

1997-12-01

This analysis was performed on the Pennsylvania State University (PSU) subcritical reactor to find more accurate values for such nuclear parameters as the thermal fuel utilization factor, thermal diffusion length in the graphite, migration area, k{sub eff}, etc. The analysis involved using the Winfrith Integrated Multigroup Scheme (WIMS) code as well as various hand calculations to find and compare those parameters. The data found in this analysis will be used by future students in the Penn State laboratory courses.

Proceedings of the Eighth Annual Thermal and Fluids Analysis Workshop: Spacecraft Analysis and Design

NASA Technical Reports Server (NTRS)

Peters, Todd (Editor); Saiz, John (Editor)

1997-01-01

This document contains papers presented at the Eighth Annual Thermal and Fluids Analysis Workshop (TFAWS) on Spacecraft Analysis and Design hosted by the NASA/Johnson Space Center (JSC) on September 8-11, 1997, and held at the University of Houston - Clear Lake (UHCL) in the Bayou Building. The Workshop was sponsored by NASA/JSC. Seminars were hosted and technical papers were provided in fluid and thermal dynamics. Seminars were given in GASP, SINDA, SINAPS Plus, TSS, and PHOENICS. Seventeen papers were presented.

SCORPION persistent surveillance system with universal gateway

NASA Astrophysics Data System (ADS)

Coster, Michael; Chambers, Jon; Winters, Michael; Belesi, Joe

2008-04-01

This paper addresses benefits derived from the universal gateway utilized in Northrop Grumman Systems Corporation's (NGSC) SCORPION, a persistent surveillance and target recognition system produced by the Xetron campus in Cincinnati, Ohio. SCORPION is currently deployed in Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF). The SCORPION universal gateway is a flexible, field programmable system that provides integration of over forty Unattended Ground Sensor (UGS) types from a variety of manufacturers, multiple visible and thermal electro-optical (EO) imagers, and numerous long haul satellite and terrestrial communications links, including the Army Research Lab (ARL) Blue Radio. Xetron has been integrating best in class sensors with this universal gateway to provide encrypted data exfiltration and remote sensor command and control since 1998. SCORPION data can be distributed point to point, or to multiple Common Operational Picture (COP) systems, including Command and Control Personal Computer (C2PC), Common Data Interchange Format for the Situational Awareness Display (CDIF/SAD), Force XXI Battle Command Brigade and Below (FBCB2), Defense Common Ground Systems (DCGS), and Remote Automated Position Identification System (RAPIDS).

Effect of long-term acclimatization on summer thermal comfort in outdoor spaces: a comparative study between Melbourne and Hong Kong.

PubMed

Lam, Cho Kwong Charlie; Lau, Kevin Ka-Lun

2018-04-12

The Universal Thermal Climate Index (UTCI) is an index for assessing outdoor thermal environment which aims to be applicable universally to different climates. However, the scale of UTCI thermal stress classification can be interpreted depending on the context. Previous studies validated the UTCI in individual cities, but comparative studies between different cities are scarce. This study examines the differences in thermal perception and clothing choices between residents from two climate zones over similar UTCI ranges in summer. We compared summer thermal comfort survey data from Melbourne (n = 2162, January-February 2014) and Hong Kong (n = 414, July-August 2007). We calculated the UTCI from outdoor weather station data and used t tests to compare the differences in thermal sensation and clothing between Hong Kong and Melbourne residents. When the UTCI was between 23.0 and 45.9 °C, Melbourne residents wore significantly more clothing (0.1 clo) than Hong Kong residents. Hong Kong residents reported neutral to warm sensation at a higher UTCI range compared with the dynamic thermal sensation (DTS) model. Moreover, Melbourne residents reported warm and hot sensation at a higher UTCI range than the DTS model. Respondents in Melbourne also exhibited different responses to the mean radiant temperature under shaded and sunny conditions, while such a trend was not observed in Hong Kong. It would be advisable to define different thermal sensation thresholds for the UTCI scale according to different climate zones for better prediction of the outdoor thermal comfort of different urban populations.

Effect of long-term acclimatization on summer thermal comfort in outdoor spaces: a comparative study between Melbourne and Hong Kong

NASA Astrophysics Data System (ADS)

Lam, Cho Kwong Charlie; Lau, Kevin Ka-Lun

2018-04-01

The Universal Thermal Climate Index (UTCI) is an index for assessing outdoor thermal environment which aims to be applicable universally to different climates. However, the scale of UTCI thermal stress classification can be interpreted depending on the context. Previous studies validated the UTCI in individual cities, but comparative studies between different cities are scarce. This study examines the differences in thermal perception and clothing choices between residents from two climate zones over similar UTCI ranges in summer. We compared summer thermal comfort survey data from Melbourne (n = 2162, January-February 2014) and Hong Kong (n = 414, July-August 2007). We calculated the UTCI from outdoor weather station data and used t tests to compare the differences in thermal sensation and clothing between Hong Kong and Melbourne residents. When the UTCI was between 23.0 and 45.9 °C, Melbourne residents wore significantly more clothing (0.1 clo) than Hong Kong residents. Hong Kong residents reported neutral to warm sensation at a higher UTCI range compared with the dynamic thermal sensation (DTS) model. Moreover, Melbourne residents reported warm and hot sensation at a higher UTCI range than the DTS model. Respondents in Melbourne also exhibited different responses to the mean radiant temperature under shaded and sunny conditions, while such a trend was not observed in Hong Kong. It would be advisable to define different thermal sensation thresholds for the UTCI scale according to different climate zones for better prediction of the outdoor thermal comfort of different urban populations.

Thermal characteristics of second harmonic generation by phase matched calorimetry.

PubMed

Lim, Hwan Hong; Kurimura, Sunao; Noguchi, Keisuke; Shoji, Ichiro

2014-07-28

We analyze a solution of the heat equation for second harmonic generation (SHG) with a focused Gaussian beam and simulate the temperature rise in SHG materials as a function of the second harmonic power and the focusing conditions. We also propose a quantitative value of the heat removal performance of SHG devices, referred to as the effective heat capacity Cα in phase matched calorimetry. We demonstrate the inverse relation between Cα and the focusing parameter ξ, and propose the universal quantity of the product of Cα and ξ for characterizing the thermal property of SHG devices. Finally, we discuss the strategy to manage thermal dephasing in SHG using the results from simulations.

Relativistic inverse Compton scattering of photons from the early universe.

PubMed

Malu, Siddharth; Datta, Abhirup; Colafrancesco, Sergio; Marchegiani, Paolo; Subrahmanyan, Ravi; Narasimha, D; Wieringa, Mark H

2017-12-05

Electrons at relativistic speeds, diffusing in magnetic fields, cause copious emission at radio frequencies in both clusters of galaxies and radio galaxies through non-thermal radiation emission called synchrotron. However, the total power radiated through this mechanism is ill constrained, as the lower limit of the electron energy distribution, or low-energy cutoffs, for radio emission in galaxy clusters and radio galaxies, have not yet been determined. This lower limit, parametrized by the lower limit of the electron momentum - p min - is critical for estimating the total energetics of non-thermal electrons produced by cluster mergers or injected by radio galaxy jets, which impacts the formation of large-scale structure in the universe, as well as the evolution of local structures inside galaxy clusters. The total pressure due to the relativistic, non-thermal population of electrons can be measured using the Sunyaev-Zel'dovich Effect, and is critically dependent on p min , making the measurement of this non-thermal pressure a promising technique to estimate the electron low-energy cutoff. We present here the first unambiguous detection of this Sunyaev-Zel'dovich Effect for a non-thermal population of electrons in a radio galaxy jet/lobe, located at a significant distance away from the center of the Bullet cluster of galaxies.

Two Stage Assessment of Thermal Hazard in An Underground Mine

NASA Astrophysics Data System (ADS)

Drenda, Jan; Sułkowski, Józef; Pach, Grzegorz; Różański, Zenon; Wrona, Paweł

2016-06-01

The results of research into the application of selected thermal indices of men's work and climate indices in a two stage assessment of climatic work conditions in underground mines have been presented in this article. The difference between these two kinds of indices was pointed out during the project entitled "The recruiting requirements for miners working in hot underground mine environments". The project was coordinated by The Institute of Mining Technologies at Silesian University of Technology. It was a part of a Polish strategic project: "Improvement of safety in mines" being financed by the National Centre of Research and Development. Climate indices are based only on physical parameters of air and their measurements. Thermal indices include additional factors which are strictly connected with work, e.g. thermal resistance of clothing, kind of work etc. Special emphasis has been put on the following indices - substitute Silesian temperature (TS) which is considered as the climatic index, and the thermal discomfort index (δ) which belongs to the thermal indices group. The possibility of the two stage application of these indices has been taken into consideration (preliminary and detailed estimation). Based on the examples it was proved that by the application of thermal hazard (detailed estimation) it is possible to avoid the use of additional technical solutions which would be necessary to reduce thermal hazard in particular work places according to the climate index. The threshold limit value for TS has been set, based on these results. It was shown that below TS = 24°C it is not necessary to perform detailed estimation.

Evaluation of thermal gradients in longitudinal spin Seebeck effect measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sola, A., E-mail: a.sola@inrim.it; Kuepferling, M.; Basso, V.

2015-05-07

In the framework of the longitudinal spin Seebeck effect (LSSE), we developed an experimental setup for the characterization of LSSE devices. This class of device consists in a layered structure formed by a substrate, a ferrimagnetic insulator (YIG) where the spin current is thermally generated, and a paramagnetic metal (Pt) for the detection of the spin current via the inverse spin-Hall effect. In this kind of experiments, the evaluation of a thermal gradient through the thin YIG layer is a crucial point. In this work, we perform an indirect determination of the thermal gradient through the measurement of the heatmore » flux. We developed an experimental setup using Peltier cells that allow us to measure the heat flux through a given sample. In order to test the technique, a standard LSSE device produced at Tohoku University was measured. We find a spin Seebeck S{sub SSE} coefficient of 2.8×10{sup −7} V K{sup −1}.« less

Validation Database Based Thermal Analysis of an Advanced RPS Concept

NASA Technical Reports Server (NTRS)

Balint, Tibor S.; Emis, Nickolas D.

2006-01-01

Advanced RPS concepts can be conceived, designed and assessed using high-end computational analysis tools. These predictions may provide an initial insight into the potential performance of these models, but verification and validation are necessary and required steps to gain confidence in the numerical analysis results. This paper discusses the findings from a numerical validation exercise for a small advanced RPS concept, based on a thermal analysis methodology developed at JPL and on a validation database obtained from experiments performed at Oregon State University. Both the numerical and experimental configurations utilized a single GPHS module enabled design, resembling a Mod-RTG concept. The analysis focused on operating and environmental conditions during the storage phase only. This validation exercise helped to refine key thermal analysis and modeling parameters, such as heat transfer coefficients, and conductivity and radiation heat transfer values. Improved understanding of the Mod-RTG concept through validation of the thermal model allows for future improvements to this power system concept.

Spacetime deformation effect on the early universe and the PTOLEMY experiment

NASA Astrophysics Data System (ADS)

Horvat, Raul; Trampetic, Josip; You, Jiangyang

2017-09-01

Using a fully-fledged formulation of gauge field theory deformed by the spacetime noncommutativity, we study its impact on relic neutrino direct detection, as proposed recently by the PTOLEMY experiment. The noncommutative background tends to influence the propagating neutrinos by providing them with a tree-level vector-like coupling to photons, enabling thus otherwise sterile right-handed (RH) neutrinos to be thermally produced in the early universe. Such a new component in the universe's background radiation has been switched today to the almost fully active sea of non-relativistic neutrinos, exerting consequently some impact on the capture on tritium at PTOLEMY. The peculiarities of our nonperturbative approach tend to reflect in the cosmology as well, upon the appearances of the coupling temperature, above which RH neutrinos stay permanently decoupled from thermal environment. This entails the maximal scale of noncommutativity as well, being of order of 10-4MPl, above which there is no impact whatsoever on the capture rates at PTOLEMY. The latter represents an exceptional upper bound on the scale of noncommutativity coming from phenomenology.

LATERAL HEAT FLOW INFRARED THERMOGRAPHY FOR THICKNESS INDEPENDENT DETERMINATION OF THERMAL DIFFUSIVITY IN CFRP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tralshawala, Nilesh; Howard, Don; Knight, Bryon

2008-02-28

In conventional infrared thermography, determination of thermal diffusivity requires thickness information. Recently GE has been experimenting with the use of lateral heat flow to determine thermal diffusivity without thickness information. This work builds on previous work at NASA Langley and Wayne State University but we incorporate thermal time of flight (tof) analysis rather than curve fitting to obtain quantitative information. We have developed appropriate theoretical models and a tof based data analysis framework to experimentally determine all components of thermal diffusivity from the time-temperature measurements. Initial validation was carried out using finite difference simulations. Experimental validation was done using anisotropicmore » carbon fiber reinforced polymer (CFRP) composites. We found that in the CFRP samples used, the in-plane component of diffusivity is about eight times larger than the through-thickness component.« less

Schwinger-Keldysh formalism. Part II: thermal equivariant cohomology

NASA Astrophysics Data System (ADS)

Haehl, Felix M.; Loganayagam, R.; Rangamani, Mukund

2017-06-01

Causally ordered correlation functions of local operators in near-thermal quantum systems computed using the Schwinger-Keldysh formalism obey a set of Ward identities. These can be understood rather simply as the consequence of a topological (BRST) algebra, called the universal Schwinger-Keldysh superalgebra, as explained in our compan-ion paper [1]. In the present paper we provide a mathematical discussion of this topological algebra. In particular, we argue that the structures can be understood in the language of extended equivariant cohomology. To keep the discussion self-contained, we provide a ba-sic review of the algebraic construction of equivariant cohomology and explain how it can be understood in familiar terms as a superspace gauge algebra. We demonstrate how the Schwinger-Keldysh construction can be succinctly encoded in terms a thermal equivariant cohomology algebra which naturally acts on the operator (super)-algebra of the quantum system. The main rationale behind this exploration is to extract symmetry statements which are robust under renormalization group flow and can hence be used to understand low-energy effective field theory of near-thermal physics. To illustrate the general prin-ciples, we focus on Langevin dynamics of a Brownian particle, rephrasing some known results in terms of thermal equivariant cohomology. As described elsewhere, the general framework enables construction of effective actions for dissipative hydrodynamics and could potentially illumine our understanding of black holes.

Thermal Cyclic Resistance Polyester Resin Composites Reinforce Fiber Nut Shell

NASA Astrophysics Data System (ADS)

Fahmi, Hendriwan

2017-12-01

The purpose of study is to determine the effect of fiber length and thermal cyclic of the bending strength of polyester resin composite reinforced by fibers nut shell. The materials used in this study is a nut shell fibers with fiber length of 1 cm, 2 cm and 3 cm and polyester resin with composition 70-30%wt. Fiber nut shell treated soaking in NaOH 30% for 30 minutes, then rinse with clean water so that the fiber free of alkali and then dried. Furthermore, the composite is heated in an oven to a temperature of 100°C for 1 hour and then cooled in the open with a variety of thermal cyclic 30, 40, and 50 times. Bending properties of composites known through the testing process using a three-point bending test equipment universal testing machine. The test results show that the bending strength bending highest in fiber length of 3 cm with 30 treatment cycles of thermal to the value of 53.325 MPa, while the lowest occurred in bending strength fiber length of 1 cm with no cycles of thermal treatment to the value of 30.675 MPa.

A Hot-Wire Method Based Thermal Conductivity Measurement Apparatus for Teaching Purposes

ERIC Educational Resources Information Center

Alvarado, S.; Marin, E.; Juarez, A. G.; Calderon, A.; Ivanov, R.

2012-01-01

The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer…

Inflationary Quasiparticle Creation and Thermalization Dynamics in Coupled Bose-Einstein Condensates

NASA Astrophysics Data System (ADS)

Posazhennikova, Anna; Trujillo-Martinez, Mauricio; Kroha, Johann

2016-06-01

A Bose gas in a double-well potential, exhibiting a true Bose-Einstein condensate (BEC) amplitude and initially performing Josephson oscillations, is a prototype of an isolated, nonequilibrium many-body system. We investigate the quasiparticle (QP) creation and thermalization dynamics of this system by solving the time-dependent Keldysh-Bogoliubov equations. We find avalanchelike QP creation due to a parametric resonance between BEC and QP oscillations, followed by slow, exponential relaxation to a thermal state at an elevated temperature, controlled by the initial excitation energy of the oscillating BEC above its ground state. The crossover between the two regimes occurs because of an effective decoupling of the QP and BEC oscillations. This dynamics is analogous to elementary particle creation in models of the early universe. The thermalization in our setup occurs because the BEC acts as a grand canonical reservoir for the quasiparticle system.

Inflationary Quasiparticle Creation and Thermalization Dynamics in Coupled Bose-Einstein Condensates.

PubMed

Posazhennikova, Anna; Trujillo-Martinez, Mauricio; Kroha, Johann

2016-06-03

A Bose gas in a double-well potential, exhibiting a true Bose-Einstein condensate (BEC) amplitude and initially performing Josephson oscillations, is a prototype of an isolated, nonequilibrium many-body system. We investigate the quasiparticle (QP) creation and thermalization dynamics of this system by solving the time-dependent Keldysh-Bogoliubov equations. We find avalanchelike QP creation due to a parametric resonance between BEC and QP oscillations, followed by slow, exponential relaxation to a thermal state at an elevated temperature, controlled by the initial excitation energy of the oscillating BEC above its ground state. The crossover between the two regimes occurs because of an effective decoupling of the QP and BEC oscillations. This dynamics is analogous to elementary particle creation in models of the early universe. The thermalization in our setup occurs because the BEC acts as a grand canonical reservoir for the quasiparticle system.

Thermal method for cleaning polymer quenching media

NASA Astrophysics Data System (ADS)

Sverdlin, A. V.; Blackwood, R.; Totten, G. E.

1996-06-01

Aqueous solutions of polymers are used for heat treatment, mainly for quenching steels. The most popular and universally used are quenching liquids of the UCON A, E, XT types based on various polyalkylene glycols. In the course of operation these liquids are contaminated by salts retained on the surface of the parts after their heating in salt baths, by ions of heavy metals present in the solution, etc. The paper is devoted to the most popular method for cleaning polymer quenching media, namely, the method of thermal separation.

Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Akoshima, Megumi; Takahashi, Satoru

2017-09-01

Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

Apollo telescope mount thermal systems unit thermal vacuum test

NASA Technical Reports Server (NTRS)

Trucks, H. F.; Hueter, U.; Wise, J. H.; Bachtel, F. D.

1971-01-01

The Apollo Telescope Mount's thermal systems unit was utilized to conduct a full-scale thermal vacuum test to verify the thermal design and the analytical techniques used to develop the thermal mathematical models. Thermal vacuum test philosophy, test objectives configuration, test monitoring, environment simulation, vehicle test performance, and data correlation are discussed. Emphasis is placed on planning and execution of the thermal vacuum test with particular attention on problems encountered in conducting a test of this maguitude.

Universal slow dynamics in granular solids

PubMed

TenCate; Smith; Guyer

2000-07-31

Experimental properties of a new form of creep dynamics are reported, as manifest in a variety of sandstones, limestone, and concrete. The creep is a recovery behavior, following the sharp drop in elastic modulus induced either by nonlinear acoustic straining or rapid temperature change. The extent of modulus recovery is universally proportional to the logarithm of the time after source discontinuation in all samples studied, over a scaling regime covering at least 10(3) s. Comparison of acoustically and thermally induced creep suggests a single origin based on internal strain, which breaks the symmetry of the inducing source.

Design study of multi-imaging plate system for BNCT irradiation field at Kyoto university reactor.

PubMed

Tanaka, Kenichi; Sakurai, Yoshinori; Kajimoto, Tsuyoshi; Tanaka, Hiroki; Takata, Takushi; Endo, Satoru

2016-09-01

The converter configuration for a multi-imaging plate system was investigated for the application of quality assurance in the irradiation field profile for boron neutron capture therapy. This was performed by the simulation calculation using the PHITS code in the fields at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. The converter constituents investigated were carbon for gamma rays, and polyethylene with and without LiF at varied (6)Li concentration for thermal, epithermal, and fast neutrons. Consequently, potential combinations of the converters were found for two components, gamma rays and thermal neutrons, for the standard thermal neutron mode and three components of gamma rays, epithermal neutrons, and thermal or fast neutrons, for the standard mixed or epithermal neutron modes, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal Management and Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Hasnain, Aqib

2016-01-01

During my internship in the Thermal Design Branch (ES3), I contributed to two main projects: i) novel passive thermal management system for future human exploration, ii) AVCOAT undercut thermal analysis. i) As NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be challenged with unprecedented thermal environments. Future exploration activities will have the need of thermal management systems that can provide higher reliability, mass and power reduction and increased performance. In an effort to start addressing the current technical gaps the NASA Johnson Space Center Passive Thermal Discipline has engaged in technology development activities. One of these activities was done through an in-house Passive Thermal Management System (PTMS) design for a lunar lander. The proposed PTMS, functional in both microgravity and gravity environments, consists of three main components: a heat spreader, a novel hybrid wick Variable Conductance Heat Pipe (VCHP), and a radiator. The aim of this PTMS is to keep electronics on a vehicle within their temperature limits (0 and 50 C for the current design) during all mission phases including multiple lunar day/night cycles. The VCHP was tested to verify its thermal performance. I created a thermal math model using Thermal Desktop (TD) and analyzed it to predict the PTMS performance. After testing, the test data provided a means to correlate the thermal math model. This correlation took into account conduction and convection heat transfer, representing the actual benchtop test. Since this PTMS is proposed for space missions, a vacuum test will be taking place to provide confidence that the system is functional in space environments. Therefore, the model was modified to include a vacuum chamber with a liquid nitrogen shroud while taking into account conduction and radiation heat transfer. Infrared Lamps were modelled and introduced into the model to simulate the sun

Solar thermal program summary. Volume 1: Overview, fiscal year 1988

NASA Astrophysics Data System (ADS)

1989-02-01

The goal of the solar thermal program is to improve overall solar thermal systems performance and provide cost-effective energy options that are strategically secure and environmentally benign. Major research activities include energy collection technology, energy conversion technology, and systems and applications technology for both CR and DR systems. This research is being conducted through research laboratories in close coordination with the solar thermal industry, utilities companies, and universities. The Solar Thermal Technology Program is pursuing the development of critical components and subsystems for improved energy collection and conversion devices. This development follows two basic paths: for CR systems, critical components include stretched membrane heliostats, direct absorption receivers (DARs), and transport subsystems for molten salt heat transfer fluids. These components offer the potential for a significant reduction in system costs; and for DR systems, critical components include stretched membrane dishes, reflux receivers, and Stirling engines. These components will significantly increase system reliability and efficiency, which will reduce costs. The major thrust of the program is to provide electric power. However, there is an increasing interest in the use of concentrated solar energy for applications such as detoxifying hazardous wastes and developing high-value transportable fuels. These potential uses of highly concentrated solar energy still require additional experiments to prove concept feasibility. The program goal of economically competitive energy reduction from solar thermal systems is being cooperatively addressed by industry and government.

Subcontinuum thermal transport in tip-based thermal engineering

NASA Astrophysics Data System (ADS)

Hamian, Sina

For the past two decades, tip-based thermal engineering has made remarkable advances to realize unprecedented nanoscale thermal applications, such as thermomechanical data storage, thermophysical/chemical property characterization of materials in nanometer scale, and scanning thermal imaging and analysis. All these applications involve localized heating with elevated temperature, generally in the order of mean free paths of heat carriers, thus necessitates fundamental understanding of sub-continuum thermal transport across point constrictions and within thin films. Considering the demands, this dissertation is divided into three main scopes providing: (1) a numerical model that provides insight onto nanoscale thermal transport, (2) an electrothermal characterization of a heated microcantilever as a localized heating source, and (3) qualitative measurement of tip-substrate thermal transport using high resolution nanothermometer/heater. This dissertation starts with a literature review on the three aforementioned scopes followed by a numerical model for two-dimensional transient ballistic-diffusive heat transfer combining finite element analysis with discrete ordinate method (DOM-FEA), seeking to provide insight on subcontinuum thermal transport. The phonon Boltzmann transport equation (BTE) under grey relaxation time approximation is solved for different Knudsen numbers. Next, a thermal microcantilever, as one of the main tools in tip-based thermal engineering, is characterized under periodic heating operation in air and vacuum using 3o technique. A three-dimensional FEA simulation of a thermal microcantilever is used to model heat transfer in frequency domain resulting in good agreement with the experiment. Next, quantitative thermal transport is measured by a home-built nanothermometer fabricated using combination of electron-beam lithography and photolithography. An atomic force microscope (AFM) cantilever is used to scan over the sensing probe of the

Thermal relics: Do we know their abundances

NASA Technical Reports Server (NTRS)

Kamionkowski, Marc; Turner, Michael S.

1990-01-01

The relic abundance of a particle species that was once in thermal equilibrium in the expanding Universe depends upon a competition between the annihilation rate of the species and the expansion rate of the Universe. Assuming that the Universe is radiation dominated at early times the relic abundance is easy to compute and well known. At times earlier than about 1 sec after the bang there is little or no evidence that the Universe had to be radiation dominated, although that is the simplest and standard assumption. Because early-Universe relics are of such importance both to particle physics and to cosmology, three nonstandard possibilities are considered in detail for the Universe at the time a species' abundance froze in: energy density dominated by shear (i.e., anisotropic expansion), energy density dominated by some other nonrelativistic species, and energy density dominated by the kinetic energy of the scalar field that sets the gravitational constant in a Brans-Dicke-Jordan cosmological mode. In the second case the relic abundance is less than the standard value, while in the other two cases it can be enhanced by a significant factor. Two other more exotic possibilities for enhancing the relic abundance of a species are also mentioned--a larger value of Newton's constant at early times (e.g., as might occur in superstring or Kaluza-Klein theories) or a component of the energy density at early times with a very stiff equation of state (p greater than rho/3), e.g., a scalar field phi with potential V(phi) = Beta /phi/ (exp n) with n greater than 4. Results have implications for dark matter searches and searches for particle relics in general.

Ultra-High Temperature Thermal Barrier Coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, Eric; Gell, Maurice; Wang, Jiwen

In this project, HiFunda LLC worked with the University of Connecticut (UConn) to demonstrate an attractive option for thermal barrier coatings (TBCs), namely yttrium aluminum garnet (YAG), which was well known to have proven thermal stability and excellent high-temperature mechanical properties. YAG and other higher temperature TBCs have not been used to date because they exhibit inadequate durability, resulting from (a) poor erosion resistance and (b) greater thermal expansion mismatch strains compared to 7YSZ. UConn had previously demonstrated that the solution precursor plasma spray (SPPS) process could produce a durable 7YSZ TBC resulting from a highly strain tolerant microstructure, consistingmore » of through-coating-thickness vertical cracks. HiFunda/UConn reasoned at the start of Phase I that such a strain-tolerant microstructure could produce durable, higher temperature TBCs. The Phase I work demonstrated the feasibility of that concept and of SPPS YAG TBCs. The Phase II work demonstrated that SPPS YAG coating possessed the necessary range of properties to be a viable high temperature TBC, including cyclic durability and reduced elevated temperature thermal conductivity. The SPPS YAG TBCs were shown to have the potential to be used at temperatures 200°C higher than APS YSZ, based on thermal stability, sinter resistance, and CMAS resistance. The overall technical objectives of this Phase 2A project were to further improve the commercial viability of SPPS by improving their performance capabilities and manufacturing economics. The improved performance capability was to be achieved through: (1) further reductions in thermal conductivity, which allows higher gas temperatures and/or thinner coatings to achieve similar gas temperatures; and (2) improved resistance to calcium magnesium alumnoslicate (CMAS) attack of the TBCs, which can yield improved lifetimes. The improved thermal conductivity and CMAs resistance was to be accomplished through compositional

Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asha, S.; Sanjeev, Ganesh, E-mail: ganeshsanjeev@rediffmail.com; Sangappa

The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated themore » antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.« less

Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films

NASA Astrophysics Data System (ADS)

Asha, S.; Sangappa, Naik, Prashantha; Chandra, K. Sharat; Sanjeev, Ganesh

2014-04-01

The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.

James Webb Space Telescope Core 2 Test - Cryogenic Thermal Balance Test of the Observatorys Core Area Thermal Control Hardware

NASA Technical Reports Server (NTRS)

Cleveland, Paul; Parrish, Keith; Thomson, Shaun; Marsh, James; Comber, Brian

2016-01-01

The James Webb Space Telescope (JWST), successor to the Hubble Space Telescope, will be the largest astronomical telescope ever sent into space. To observe the very first light of the early universe, JWST requires a large deployed 6.5-meter primary mirror cryogenically cooled to less than 50 Kelvin. Three scientific instruments are further cooled via a large radiator system to less than 40 Kelvin. A fourth scientific instrument is cooled to less than 7 Kelvin using a combination pulse-tube Joule-Thomson mechanical cooler. Passive cryogenic cooling enables the large scale of the telescope which must be highly folded for launch on an Ariane 5 launch vehicle and deployed once on orbit during its journey to the second Earth-Sun Lagrange point. Passive cooling of the observatory is enabled by the deployment of a large tennis court sized five layer Sunshield combined with the use of a network of high efficiency radiators. A high purity aluminum heat strap system connects the three instrument's detector systems to the radiator systems to dissipate less than a single watt of parasitic and instrument dissipated heat. JWST's large scale features, while enabling passive cooling, also prevent the typical flight configuration fully-deployed thermal balance test that is the keystone of most space missions' thermal verification plans. This paper describes the JWST Core 2 Test, which is a cryogenic thermal balance test of a full size, high fidelity engineering model of the Observatory's 'Core' area thermal control hardware. The 'Core' area is the key mechanical and cryogenic interface area between all Observatory elements. The 'Core' area thermal control hardware allows for temperature transition of 300K to approximately 50 K by attenuating heat from the room temperature IEC (instrument electronics) and the Spacecraft Bus. Since the flight hardware is not available for test, the Core 2 test uses high fidelity and flight-like reproductions.

Thermal cycling fatigue of organic thermal interface materials using a thermal-displacement measurement technique

NASA Astrophysics Data System (ADS)

Steill, Jason Scott

The long term reliability of polymer-based thermal interface materials (TIM) is essential for modern electronic packages which require robust thermal management. The challenge for today's materials scientists and engineers is to maximize the heat flow from integrated circuits through a TIM and out the heat sink. Thermal cycling of the electronic package and non-uniformity in the heat flux with respect to the plan area can lead to void formation and delamination which re-introduces inefficient heat transfer. Measurement and understanding at the nano-scale is essential for TIM development. Finding and documenting the evolution of the defects is dependent upon a full understanding of the thermal probes response to changing environmental conditions and the effects of probe usage. The response of the thermal-displacement measurement technique was dominated by changes to the environment. Accurate measurement of the thermal performance was hindered by the inability to create a model system and control the operating conditions. This research highlights the need for continued study into the probe's thermal and mechanical response using tightly controlled test conditions.

Universal binding energy relations in metallic adhesion

NASA Technical Reports Server (NTRS)

Ferrante, J.; Smith, J. R.; Rose, J. J.

1984-01-01

Rose, Smith, and Ferrante have discovered scaling relations which map the adhesive binding energy calculated by Ferrante and Smith onto a single universal binding energy curve. These binding energies are calculated for all combinations of Al(111), Zn(0001), Mg(0001), and Na(110) in contact. The scaling involves normalizing the energy by the maximum binding energy and normalizing distances by a suitable combination of Thomas-Fermi screening lengths. Rose et al. have also found that the calculated cohesive energies of K, Ba, Cu, Mo, and Sm scale by similar simple relations, suggesting the universal relation may be more general than for the simple free electron metals for which it was derived. In addition, the scaling length was defined more generally in order to relate it to measurable physical properties. Further this universality can be extended to chemisorption. A simple and yet quite accurate prediction of a zero temperature equation of state (volume as a function of pressure for metals and alloys) is presented. Thermal expansion coefficients and melting temperatures are predicted by simple, analytic expressions, and results compare favorably with experiment for a broad range of metals.

Development of high flux thermal neutron generator for neutron activation analysis

NASA Astrophysics Data System (ADS)

Vainionpaa, Jaakko H.; Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K.; Jones, Glenn; Pantell, Richard H.

2015-05-01

The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3-5 · 107 n/cm2/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2 · 1010 n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

Experimental thermal characterization of concrete to be used in CP5.2 packaging system

NASA Astrophysics Data System (ADS)

Lo Frano, R.; Maggini, A.; Aquaro, D.

2017-01-01

This work deals with the experimental evaluation of the thermal conductivity of a concrete matrix to be used for embedding LILW bituminised Wastes into the packaging system. Such a type of packaging, identified with the acronym CP5.2, has been also qualified by executing at the Lab. Scalbatraio of Dep. of Civil and Industrial Engineering of the University of Pisa, an experimental test campaign accordingly to the IAEA regulations. In particular, the knowledge of the thermal conductivity is important because of the fire or furnace test to carry out in oven at 800 °C for 30 minutes. These data allowed to simulate pre-test conditions and to set up safety and operational fire test procedures. The concrete thermal conductivity was obtained by performing hot wire tests on cylindrical concrete samples for temperatures ranging from 100° to about 800°C. Thermal conductivity is determined at steady state condition. Results indicate a monotonically reduction of the thermal conductivity as the temperature increases. The comparison with concrete thermal conductivity data available in literature indicates a quite good agreement. Finally, visual and X-ray inspection of sample did not highlight the presence of micro/macro damages that would have affected the thermal performance of the concrete under study.

Revisiting the Birth of 7YSZ Thermal Barrier Coatings: Steve Stecura

NASA Technical Reports Server (NTRS)

Smialek, James L.; Miller, Robert A.

2017-01-01

Thermal barrier coatings are widely used in all turbine engines, typically using a 7 wt% Y2O3-ZrO2 formulation. Extensive research and development over many decades have refined the processing and structure of these coatings for increased durability and reliability. New compositions demonstrate some unique advantages and are gaining in application. However, the "7YSZ" formulation predominates and is still in widespread use. This special composition has been universally found to produce nanoscale precipitates of metastable t' tetragonal phase, giving rise to a unique toughening mechanism via ferro-elastic switching under stress. This note recalls the original study that identified superior properties of 6 to 8 wt% YSZ plasma sprayed thermal barrier coatings, published in 1978. The impact of this discovery, arguably, continues in some form to this day. At one point, 7YSZ thermal barrier coatings were used in every new aircraft and ground power turbine engine produced worldwide. It is a tribute to its inventor, Dr. Stephan J. Stecura, NASA retiree.

A review of carbide fuel corrosion for nuclear thermal propulsion applications

NASA Astrophysics Data System (ADS)

Pelaccio, Dennis G.; El-Genk, Mohamed S.; Butt, Darryl P.

1993-10-01

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

A Review of Carbide Fuel Corrosion for Nuclear Thermal Propulsion Applications

NASA Astrophysics Data System (ADS)

Pelaccio, Dennis G.; El-Genk, Mohamed S.; Butt, Darryl P.

1994-07-01

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

Effect of carbon dioxide on the thermal degradation of lignocellulosic biomass.

PubMed

Kwon, Eilhann E; Jeon, Eui-Chan; Castaldi, Marco J; Jeon, Young Jae

2013-09-17

Using biomass as a renewable energy source via currently available thermochemical processes (i.e., pyrolysis and gasification) is environmentally advantageous owing to its intrinsic carbon neutrality. Developing methodologies to enhance the thermal efficiency of these proven technologies is therefore imperative. This study aimed to investigate the use of CO2 as a reaction medium to increase not only thermal efficiency but also environmental benefit. The influence of CO2 on thermochemical processes at a fundamental level was experimentally validated with the main constituents of biomass (i.e., cellulose and xylan) to avoid complexities arising from the heterogeneous matrix of biomass. For instance, gaseous products including H2, CH4, and CO were substantially enhanced in the presence of CO2 because CO2 expedited thermal cracking behavior (i.e., 200-1000%). This behavior was then universally observed in our case study with real biomass (i.e., corn stover) during pyrolysis and steam gasification. However, further study is urgently needed to optimize these experimental findings.

Implications of Thermal Diffusity being Inversely Proportional to Temperature Times Thermal Expansivity on Lower Mantle Heat Transport

NASA Astrophysics Data System (ADS)

Hofmeister, A.

2010-12-01

Many measurements and models of heat transport in lower mantle candidate phases contain systematic errors: (1) conventional methods of insulators involve thermal losses that are pressure (P) and temperature (T) dependent due to physical contact with metal thermocouples, (2) measurements frequently contain unwanted ballistic radiative transfer which hugely increases with T, (3) spectroscopic measurements of dense samples in diamond anvil cells involve strong refraction by which has not been accounted for in analyzing transmission data, (4) the role of grain boundary scattering in impeding heat and light transfer has largely been overlooked, and (5) essentially harmonic physical properties have been used to predict anharmonic behavior. Improving our understanding of the physics of heat transport requires accurate data, especially as a function of temperature, where anharmonicity is the key factor. My laboratory provides thermal diffusivity (D) at T from laser flash analysis, which lacks the above experimental errors. Measuring a plethora of chemical compositions in diverse dense structures (most recently, perovskites, B1, B2, and glasses) as a function of temperature provides a firm basis for understanding microscopic behavior. Given accurate measurements for all quantities: (1) D is inversely proportional to [T x alpha(T)] from ~0 K to melting, where alpha is thermal expansivity, and (2) the damped harmonic oscillator model matches measured D(T), using only two parameters (average infrared dielectric peak width and compressional velocity), both acquired at temperature. These discoveries pertain to the anharmonic aspects of heat transport. I have previously discussed the easily understood quasi-harmonic pressure dependence of D. Universal behavior makes application to the Earth straightforward: due to the stiffness and slow motions of the plates and interior, and present-day, slow planetary cooling rates, Earth can be approximated as being in quasi

An analysis of influential factors on outdoor thermal comfort in summer.

PubMed

Yin, JiFu; Zheng, YouFei; Wu, RongJun; Tan, JianGuo; Ye, DianXiu; Wang, Wei

2012-09-01

A variety of research has linked high temperature to outdoor thermal comfort in summer, but it remains unclear how outdoor meteorological environments influence people's thermal sensation in subtropical monsoon climate areas, especially in China. In order to explain the process, and to better understand the related influential factors, we conducted an extensive survey of thermally comfortable conditions in open outdoor spaces. The goal of this study was to gain an insight into the subjects' perspectives on weather variables and comfort levels, and determine the factors responsible for the varying human thermal comfort response in summer. These perceptions were then compared to actual ambient conditions. The database consists of surveys rated by 205 students trained from 6:00 am to 8:00 pm outdoors from 21 to 25 August 2009, at Nanjing University of Information Science & Technology (NUIST), Nanjing, China. The multiple regression approach and simple factor analysis of variance were used to investigate the relationships between thermal comfort and meteorological environment, taking into consideration individual mood, gender, level of regular exercise, and previous environmental experiences. It was found that males and females have similar perceptions of maximum temperature; in the most comfortable environment, mood appears to have a significant influence on thermal comfort, but the influence of mood diminishes as the meteorological environment becomes increasingly uncomfortable. In addition, the study confirms the strong relationship between thermal comfort and microclimatic conditions, including solar radiation, atmospheric pressure, maximum temperature, wind speed and relative humidity, ranked by importance. There are also strong effects of illness, clothing and exercise, all of which influence thermal comfort. We also find that their former place of residence influences people's thermal comfort substantially by setting expectations. Finally, some relationships

An analysis of influential factors on outdoor thermal comfort in summer

NASA Astrophysics Data System (ADS)

Yin, JiFu; Zheng, YouFei; Wu, RongJun; Tan, JianGuo; Ye, DianXiu; Wang, Wei

2012-09-01

A variety of research has linked high temperature to outdoor thermal comfort in summer, but it remains unclear how outdoor meteorological environments influence people's thermal sensation in subtropical monsoon climate areas, especially in China. In order to explain the process, and to better understand the related influential factors, we conducted an extensive survey of thermally comfortable conditions in open outdoor spaces. The goal of this study was to gain an insight into the subjects' perspectives on weather variables and comfort levels, and determine the factors responsible for the varying human thermal comfort response in summer. These perceptions were then compared to actual ambient conditions. The database consists of surveys rated by 205 students trained from 6:00 am to 8:00 pm outdoors from 21 to 25 August 2009, at Nanjing University of Information Science & Technology (NUIST), Nanjing, China. The multiple regression approach and simple factor analysis of variance were used to investigate the relationships between thermal comfort and meteorological environment, taking into consideration individual mood, gender, level of regular exercise, and previous environmental experiences. It was found that males and females have similar perceptions of maximum temperature; in the most comfortable environment, mood appears to have a significant influence on thermal comfort, but the influence of mood diminishes as the meteorological environment becomes increasingly uncomfortable. In addition, the study confirms the strong relationship between thermal comfort and microclimatic conditions, including solar radiation, atmospheric pressure, maximum temperature, wind speed and relative humidity, ranked by importance. There are also strong effects of illness, clothing and exercise, all of which influence thermal comfort. We also find that their former place of residence influences people's thermal comfort substantially by setting expectations. Finally, some relationships

Virasoro conformal blocks and thermality from classical background fields

DOE PAGES

Fitzpatrick, A. Liam; Kaplan, Jared; Walters, Matthew T.

2015-11-30

We show that in 2d CFTs at large central charge, the coupling of the stress tensor to heavy operators can be re-absorbed by placing the CFT in a non-trivial background metric. This leads to a more precise computation of the Virasoro conformal blocks between heavy and light operators, which are shown to be equivalent to global conformal blocks evaluated in the new background. We also generalize to the case where the operators carry U(1) charges. The refined Virasoro blocks can be used as the seed for a new Virasoro block recursion relation expanded in the heavy-light limit. Furthermore, we commentmore » on the implications of our results for the universality of black hole thermality in AdS 3 , or equivalently, the eigenstate thermalization hypothesis for CFT 2 at large central charge.« less

Thermal Diffusivity Measurements in Edible Oils using Transient Thermal Lens

NASA Astrophysics Data System (ADS)

Valdez, R. Carbajal.; Pérez, J. L. Jiménez.; Cruz-Orea, A.; Martín-Martínez, E. San.

2006-11-01

Time resolved thermal lens (TL) spectrometry is applied to the study of the thermal diffusivity of edible oils such as olive, and refined and thermally treated avocado oils. A two laser mismatched-mode experimental configuration was used, with a He Ne laser as a probe beam and an Ar+ laser as the excitation one. The characteristic time constant of the transient thermal lens was obtained by fitting the experimental data to the theoretical expression for a transient thermal lens. The results showed that virgin olive oil has a higher thermal diffusivity than for refined and thermally treated avocado oils. This measured thermal property may contribute to a better understanding of the quality of edible oils, which is very important in the food industry. The thermal diffusivity results for virgin olive oil, obtained from this technique, agree with those reported in the literature.

Thermally Optimized Paradigm of Thermal Management (TOP-M)

DTIC Science & Technology

2017-07-18

ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 6. AUTHOR(S) 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8...19b. TELEPHONE NUMBER (Include area code) 18-07-2017 Final Technical Jul 2015 - Jul 2017 NICOP - Thermally Optimized Paradigm of Thermal Management ...The main goal of this research was to present a New Thermal Management Approach, which combines thermally aware Very/Ultra Large Scale Integration

Probing Models of Dark Matter and the Early Universe

NASA Astrophysics Data System (ADS)

Orlofsky, Nicholas David

This thesis discusses models for dark matter (DM) and their behavior in the early universe. An important question is how phenomenological probes can directly search for signals of DM today. Another topic of investigation is how the DM and other processes in the early universe must evolve. Then, astrophysical bounds on early universe dynamics can constrain DM. We will consider these questions in the context of three classes of DM models--weakly interacting massive particles (WIMPs), axions, and primordial black holes (PBHs). Starting with WIMPs, we consider models where the DM is charged under the electroweak gauge group of the Standard Model. Such WIMPs, if generated by a thermal cosmological history, are constrained by direct detection experiments. To avoid present or near-future bounds, the WIMP model or cosmological history must be altered in some way. This may be accomplished by the inclusion of new states that coannihilate with the WIMP or a period of non-thermal evolution in the early universe. Future experiments are likely to probe some of these altered scenarios, and a non-observation would require a high degree of tuning in some of the model parameters in these scenarios. Next, axions, as light pseudo-Nambu-Goldstone bosons, are susceptible to quantum fluctuations in the early universe that lead to isocurvature perturbations, which are constrained by observations of the cosmic microwave background (CMB). We ask what it would take to allow axion models in the face of these strong CMB bounds. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed, elucidating the difficulties in these constructions. Avoiding disruption of inflationary dynamics provides important limits on the parameter space. Finally, PBHs have received interest in part due to observations by LIGO of merging black hole binaries. We ask how these PBHs could arise through inflationary models and investigate the opportunity

Carbon nanotube thermal interfaces and related applications

NASA Astrophysics Data System (ADS)

Hodson, Stephen L.

compressive load. The thermal performance was further improved by infiltrating the CNT TIM with paraffin wax, which serves as an alternate pathway for heat conduction across the interface that ultimately reduces the bulk thermal resistance of the CNT TIM. For CNT TIMs synthesized at the Birck Nanotechnology Center at Purdue University, the thermal resistance was shown to scale linearly with their aggregate, as-grown height. Thus, the bulk thermal resistance can alternatively be tuned by adjusting the as-grown height. The linear relationship between thermal resistance and CNT TIM height provides a simple and efficient methodology to estimate the contact resistance and effective thermal conductivity of CNT TIMs. In this work, the contact resistance and effective thermal conductivity were estimated using two measurement techniques: (i) one-dimensional, steady-state reference bar and (ii) photoacoustic technique. A discrepancy in the estimated contact resistance exists between the two measurement techniques, which is due to the difficulty in measuring the true contact area. In contrast, the effective thermal conductivities estimated from both measurement techniques moderately agreed and were estimated to be on the order of O(1 W/mK). The final chapter is in collaboration with Sandia National Laboratories and focuses on the development of an apparatus to measure the thermal conductivity of insulation materials critical for the operation of molten salt batteries. Molten salt batteries are particularly useful power sources for radar and guidance systems in military applications such as guided missiles, ordinance, and other weapons. Molten salt batteries are activated by raising the temperature of the electrolyte above its melting temperature using pyrotechnic heat pellets. The battery will remain active as long as the electrolyte is molten. As a result, the thermal processes within the components and interactions between them are critical to the overall performance of molten salt

Non-thermal pressure in the outskirts of Abell 2142

NASA Astrophysics Data System (ADS)

Fusco-Femiano, Roberto; Lapi, Andrea

2018-03-01

Clumping and turbulence are expected to affect the matter accreted on to the outskirts of galaxy clusters. To determine their impact on the thermodynamic properties of Abell 2142, we perform an analysis of the X-ray temperature data from XMM-Newton via our SuperModel, a state-of-the-art tool for investigating the astrophysics of the intracluster medium already tested on many individual clusters (since Cavaliere, Lapi & Fusco-Femiano 2009). Using the gas density profile corrected for clumpiness derived by Tchernin et al. (2016), we find evidence for the presence of a non-thermal pressure component required to sustain gravity in the cluster outskirts of Abell 2142, that amounts to about 30 per cent of the total pressure at the virial radius. The presence of the non-thermal component implies the gas fraction to be consistent with the universal value at the virial radius and the electron thermal pressure profile to be in good agreement with that inferred from the SZ data. Our results indicate that the presence of gas clumping and of a non-thermal pressure component are both necessary to recover the observed physical properties in the cluster outskirts. Moreover, we stress that an alternative method often exploited in the literature (included Abell 2142) to determine the temperature profile kBT = Pe/ne basing on a combination of the Sunyaev-Zel'dovich (SZ) pressure Pe and of the X-ray electron density ne does not allow us to highlight the presence of non-thermal pressure support in the cluster outskirts.

Dealing with the increased radon concentration in thermally retrofitted buildings.

PubMed

Jiránek, M; Kačmaříková, V

2014-07-01

The influence of energy-saving measures on indoor radon concentration has been studied on the basis of a family house made of clinker concrete wall panels containing from 1000 up to 4000 Bq kg(-1) of 226Ra. Thermal retrofitting based on installing external thermal insulation composite system on the building envelope and replacing existing windows by new ones decreased the annual energy need for heating 2.8 times, but also reduced the ventilation rate to values<0.1 h(-1). As a consequence, the 1-y average indoor radon concentration values increased 3.4 times from 337 to 1117 Bq m(-3). The additional risk of lung cancer in the thermally retrofitted house increased to a value that is 125 % higher than before conversion. Methods for dealing with this enhanced risk by increasing the ventilation rate are discussed. Recovery of investments and the energy consequences of increased ventilation are studied in a long-term perspective. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Capillary Two-Phase Thermal Devices for Space Applications

NASA Technical Reports Server (NTRS)

Ku, Jentung

2016-01-01

This is the presentation file for an invited seminar for Department of Mechanical and Aerospace Engineering at the Case Western Reserve University. The seminar is scheduled for April 1, 2016.Description: This presentation will discuss operating principles and performance characteristics of heat pipes (HPs) and loop heat pipes (LHPs) and their application for spacecraft thermal control. Topics include: 1) HP operating principles; 2) HP performance characteristics; 3) LHP pressure profiles; 4) LHP operating temperature; 5) LHP operating temperature control; and 6) Examples of using HPs and LHPs on NASA flight projects.

Universality of local dissipation scales in buoyancy-driven turbulence.

PubMed

Zhou, Quan; Xia, Ke-Qing

2010-03-26

We report an experimental investigation of the local dissipation scale field eta in turbulent thermal convection. Our results reveal two types of universality of eta. The first one is that, for the same flow, the probability density functions (PDFs) of eta are insensitive to turbulent intensity and large-scale inhomogeneity and anisotropy of the system. The second is that the small-scale dissipation dynamics in buoyancy-driven turbulence can be described by the same models developed for homogeneous and isotropic turbulence. However, the exact functional form of the PDF of the local dissipation scale is not universal with respect to different types of flows, but depends on the integral-scale velocity boundary condition, which is found to have an exponential, rather than Gaussian, distribution in turbulent Rayleigh-Bénard convection.

Battery Thermal Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keyser, Matthew; Saxon, Aron; Powell, Mitchell

2016-06-07

This poster shows the progress in battery thermal characterization over the previous year. NREL collaborated with U.S. DRIVE and USABC battery developers to obtain thermal properties of their batteries, obtained heat capacity and heat generation of cells under various power profiles, obtained thermal images of the cells under various drive cycles, and used the measured results to validate thermal models. Thermal properties are used for the thermal analysis and design of improved battery thermal management systems to support achieve life and performance targets.

Non-Fourier based thermal-mechanical tissue damage prediction for thermal ablation.

PubMed

Li, Xin; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

2017-01-02

Prediction of tissue damage under thermal loads plays important role for thermal ablation planning. A new methodology is presented in this paper by combing non-Fourier bio-heat transfer, constitutive elastic mechanics as well as non-rigid motion of dynamics to predict and analyze thermal distribution, thermal-induced mechanical deformation and thermal-mechanical damage of soft tissues under thermal loads. Simulations and comparison analysis demonstrate that the proposed methodology based on the non-Fourier bio-heat transfer can account for the thermal-induced mechanical behaviors of soft tissues and predict tissue thermal damage more accurately than classical Fourier bio-heat transfer based model.

Thermal sensation and climate: a comparison of UTCI and PET thresholds in different climates.

PubMed

Pantavou, Katerina; Lykoudis, Spyridon; Nikolopoulou, Marialena; Tsiros, Ioannis X

2018-06-07

The influence of physiological acclimatization and psychological adaptation on thermal perception is well documented and has revealed the importance of thermal experience and expectation in the evaluation of environmental stimuli. Seasonal patterns of thermal perception have been studied, and calibrated thermal indices' scales have been proposed to obtain meaningful interpretations of thermal sensation indices in different climate regions. The current work attempts to quantify the contribution of climate to the long-term thermal adaptation by examining the relationship between climate normal annual air temperature (1971-2000) and such climate-calibrated thermal indices' assessment scales. The thermal sensation ranges of two thermal indices, the Universal Thermal Climate Index (UTCI) and the Physiological Equivalent Temperature Index (PET), were calibrated for three warm temperate climate contexts (Cfa, Cfb, Csa), against the subjective evaluation of the thermal environment indicated by interviewees during field surveys conducted at seven European cities: Athens (GR), Thessaloniki (GR), Milan (IT), Fribourg (CH), Kassel (DE), Cambridge (UK), and Sheffield (UK), under the same research protocol. Then, calibrated scales for other climate contexts were added from the literature, and the relationship between the respective scales' thresholds and climate normal annual air temperature was examined. To maintain the maximum possible comparability, three methods were applied for the calibration, namely linear, ordinal, and probit regression. The results indicated that the calibrated UTCI and PET thresholds increase with the climate normal annual air temperature of the survey city. To investigate further climates, we also included in the analysis results of previous studies presenting only thresholds for neutral thermal sensation. The average increase of the respective thresholds in the case of neutral thermal sensation was about 0.6 °C for each 1 °C increase of the

Thermal sensation and climate: a comparison of UTCI and PET thresholds in different climates

NASA Astrophysics Data System (ADS)

Pantavou, Katerina; Lykoudis, Spyridon; Nikolopoulou, Marialena; Tsiros, Ioannis X.

2018-06-01

The influence of physiological acclimatization and psychological adaptation on thermal perception is well documented and has revealed the importance of thermal experience and expectation in the evaluation of environmental stimuli. Seasonal patterns of thermal perception have been studied, and calibrated thermal indices' scales have been proposed to obtain meaningful interpretations of thermal sensation indices in different climate regions. The current work attempts to quantify the contribution of climate to the long-term thermal adaptation by examining the relationship between climate normal annual air temperature (1971-2000) and such climate-calibrated thermal indices' assessment scales. The thermal sensation ranges of two thermal indices, the Universal Thermal Climate Index (UTCI) and the Physiological Equivalent Temperature Index (PET), were calibrated for three warm temperate climate contexts (Cfa, Cfb, Csa), against the subjective evaluation of the thermal environment indicated by interviewees during field surveys conducted at seven European cities: Athens (GR), Thessaloniki (GR), Milan (IT), Fribourg (CH), Kassel (DE), Cambridge (UK), and Sheffield (UK), under the same research protocol. Then, calibrated scales for other climate contexts were added from the literature, and the relationship between the respective scales' thresholds and climate normal annual air temperature was examined. To maintain the maximum possible comparability, three methods were applied for the calibration, namely linear, ordinal, and probit regression. The results indicated that the calibrated UTCI and PET thresholds increase with the climate normal annual air temperature of the survey city. To investigate further climates, we also included in the analysis results of previous studies presenting only thresholds for neutral thermal sensation. The average increase of the respective thresholds in the case of neutral thermal sensation was about 0.6 °C for each 1 °C increase of the normal

Methods of forming thermal management systems and thermal management methods

DOEpatents

Gering, Kevin L.; Haefner, Daryl R.

2012-06-05

A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

Solar Simulation for the CREST Preflight Thermal-Vacuum Test at B-2

NASA Technical Reports Server (NTRS)

Ziemke, Robert A.

2013-01-01

In June 2011, the multi-university sponsored Cosmic Ray Electron Synchrotron Telescope (CREST) has undergone thermal-vacuum qualification testing at the NASA Glenn Research Center (GRC), Plum Brook Station, Sandusky, Ohio. The testing was performed in the B- 2 Space Propulsion Facility vacuum chamber. The CREST was later flown over the Antarctic region as the payload of a stratospheric balloon. Solar simulation was provided by a system of planar infrared lamp arrays specifically designed for CREST. The lamp arrays, in conjunction with a liquid-nitrogen-cooled cryoshroud, achieved the required thermal conditions for the qualification tests. This report focuses on the design and analysis of the planar arrays based on first principles. Computational spreadsheets are included in the report.

Thermal Fatigue and Fracture Behavior of Ceramic Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, Sung R.; Miller, Robert A.

2001-01-01

Thermal fatigue and fracture behavior of plasma-sprayed ceramic thermal barrier coatings has been investigated under high heat flux and thermal cyclic conditions. The coating crack propagation is studied under laser heat flux cyclic thermal loading, and is correlated with dynamic fatigue and strength test results. The coating stress response and inelasticity, fatigue and creep interactions, and interface damage mechanisms during dynamic thermal fatigue processes are emphasized.

Thermal design trades for SAFIR architecture concepts

NASA Technical Reports Server (NTRS)

Yorke, Harold W.; Paine, Christopher; Bradford, Matt; Dragovan, Mark; Nash, Al; Dooley, Jennifer; Lawrence, Charles

2004-01-01

SAFIR is a IO-meter, 4 K space telescope optimized for wavelengths between 20 microns and 1 mm. The combination of aperture diameter and telescope temperature will provide a raw sensitivity improvement of more than a factor of 1000 over presently-planned missions. The sensitivity will be comparable to that of the JWST and ALMA, but at the critical far-IR wavelengths where much of the universe's radiative energy has emerged since the origin of stars and galaxies. We examine several of the critical technologies for SAFIR which enable the large cold aperture, and present results of studies examining the telescope optics and the spacecraft thermal architecture. Both the method by which the aperture is filled, and the overall optical design for the telescope can impact the potential scientific return of SAFIR. Thermal architecture that goes far beyond the sunshades developed for the James Webb Space Telescope will be necessary to achieve the desired sensitivity of SAFIR. By combining active and passive cooling at critical points within the observatory, a significant reduction of the required level of active cooling can be obtained.

Bioclimatic comfort and the thermal perceptions and preferences of beach tourists

NASA Astrophysics Data System (ADS)

Rutty, Michelle; Scott, Daniel

2015-01-01

The largest market segment of global tourism is coastal tourism, which is strongly dependent on the destination's thermal climate. To date, outdoor bioclimatic comfort assessments have focused exclusively on local residents in open urban areas, making it unclear whether outdoor comfort is perceived differently in non-urban environments or by non-residents (i.e. tourists) with different weather expectations and activity patterns. This study provides needed insight into the perception of outdoor microclimatic conditions in a coastal environment while simultaneously identifying important psychological factors that differentiate tourists from everyday users of urban spaces. Concurrent micrometeorological measurements were taken on several Caribbean beaches in the islands of Barbados, Saint Lucia and Tobago, while a questionnaire survey was used to examine the thermal comfort of subjects ( n = 472). Universal Thermal Climate Index (UTCI) conditions of 32 to 39 °C were recorded, which were perceived as being "slightly warm" or "warm" by respondents. Most beach users (48 to 77 %) would not change the thermal conditions, with some (4 to 15 %) preferring even warmer conditions. Even at UTCI of 39 °C, 62 % of respondents voted for no change to current thermal conditions, with an additional 10 % stating that they would like to feel even warmer. These results indicate that beach users' thermal preferences are up to 18 °C warmer than the preferred thermal conditions identified in existing outdoor bioclimatic studies from urban park settings. This indicates that beach users hold fundamentally different comfort perceptions and preferences compared to people using urban spaces. Statistically significant differences ( p ≤ .05) were also recorded for demographic groups (gender, age) and place of origin (climatic region).

NASA Goddard Thermal Technology Overview 2016

NASA Technical Reports Server (NTRS)

Butler, Dan; Swanson, Ted

2016-01-01

This presentation summarizes the current plans and efforts at NASA Goddard to develop new thermal control technology for anticipated future missions. It will also address some of the programmatic developments currently underway at NASA, especially with respect to the NASA Technology Development Program. The effects of the recently enacted FY 16 NASA budget, which includes a sizeable increase, will also be addressed. While funding for basic technology development is still tight, significant efforts are being made in direct support of flight programs. Thermal technology implementation on current flight programs will be reviewed, and the recent push for Cube-sat mission development will also be addressed. Many of these technologies also have broad applicability to DOD, DOE, and commercial programs. Partnerships have been developed with the Air Force, Navy, and various universities to promote technology development. In addition, technology development activities supported by internal research and development (IRAD) program and the Small Business Innovative Research (SBIR) program are reviewed in this presentation. Specific technologies addressed include; two-phase systems applications and issues on NASA missions, latest developments of electro-hydrodynamically pumped systems, Atomic Layer Deposition (ALD), Micro-scale Heat Transfer, and various other research activities.

Thermal modelling using discrete vasculature for thermal therapy: a review

PubMed Central

Kok, H.P.; Gellermann, J.; van den Berg, C.A.T.; Stauffer, P.R.; Hand, J.W.; Crezee, J.

2013-01-01

Reliable temperature information during clinical hyperthermia and thermal ablation is essential for adequate treatment control, but conventional temperature measurements do not provide 3D temperature information. Treatment planning is a very useful tool to improve treatment quality and substantial progress has been made over the last decade. Thermal modelling is a very important and challenging aspect of hyperthermia treatment planning. Various thermal models have been developed for this purpose, with varying complexity. Since blood perfusion is such an important factor in thermal redistribution of energy in in vivo tissue, thermal simulations are most accurately performed by modelling discrete vasculature. This review describes the progress in thermal modelling with discrete vasculature for the purpose of hyperthermia treatment planning and thermal ablation. There has been significant progress in thermal modelling with discrete vasculature. Recent developments have made real-time simulations possible, which can provide feedback during treatment for improved therapy. Future clinical application of thermal modelling with discrete vasculature in hyperthermia treatment planning is expected to further improve treatment quality. PMID:23738700

Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

NASA Technical Reports Server (NTRS)

Weckmann, Stephanie

1997-01-01

The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

Non-Fourier based thermal-mechanical tissue damage prediction for thermal ablation

PubMed Central

Li, Xin; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

2017-01-01

ABSTRACT Prediction of tissue damage under thermal loads plays important role for thermal ablation planning. A new methodology is presented in this paper by combing non-Fourier bio-heat transfer, constitutive elastic mechanics as well as non-rigid motion of dynamics to predict and analyze thermal distribution, thermal-induced mechanical deformation and thermal-mechanical damage of soft tissues under thermal loads. Simulations and comparison analysis demonstrate that the proposed methodology based on the non-Fourier bio-heat transfer can account for the thermal-induced mechanical behaviors of soft tissues and predict tissue thermal damage more accurately than classical Fourier bio-heat transfer based model. PMID:27690290

Micromachined Chip Scale Thermal Sensor for Thermal Imaging.

PubMed

Shekhawat, Gajendra S; Ramachandran, Srinivasan; Jiryaei Sharahi, Hossein; Sarkar, Souravi; Hujsak, Karl; Li, Yuan; Hagglund, Karl; Kim, Seonghwan; Aden, Gary; Chand, Ami; Dravid, Vinayak P

2018-02-27

The lateral resolution of scanning thermal microscopy (SThM) has hitherto never approached that of mainstream atomic force microscopy, mainly due to poor performance of the thermal sensor. Herein, we report a nanomechanical system-based thermal sensor (thermocouple) that enables high lateral resolution that is often required in nanoscale thermal characterization in a wide range of applications. This thermocouple-based probe technology delivers excellent lateral resolution (∼20 nm), extended high-temperature measurements >700 °C without cantilever bending, and thermal sensitivity (∼0.04 °C). The origin of significantly improved figures-of-merit lies in the probe design that consists of a hollow silicon tip integrated with a vertically oriented thermocouple sensor at the apex (low thermal mass) which interacts with the sample through a metallic nanowire (50 nm diameter), thereby achieving high lateral resolution. The efficacy of this approach to SThM is demonstrated by imaging embedded metallic nanostructures in silica core-shell, metal nanostructures coated with polymer films, and metal-polymer interconnect structures. The nanoscale pitch and extremely small thermal mass of the probe promise significant improvements over existing methods and wide range of applications in several fields including semiconductor industry, biomedical imaging, and data storage.

Universal pion freeze-out in heavy-ion collisions.

PubMed

Adamová, D; Agakichiev, G; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanović, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Milov, A; Miśkowiec, D; Panebrattsev, Yu; Petchenova, O; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Slívová, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

2003-01-17

Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.

Vacant habitats in the Universe.

PubMed

Cockell, Charles S

2011-02-01

The search for life on other planets usually makes the assumption that where there is a habitat, it will contain life. On the present-day Earth, uninhabited habitats (or vacant habitats) are rare, but might occur, for example, in subsurface oils or impact craters that have been thermally sterilized in the past. Beyond Earth, vacant habitats might similarly exist on inhabited planets or on uninhabited planets, for example on a habitable planet where life never originated. The hypothesis that vacant habitats are abundant in the Universe is testable by studying other planets. In this review, I discuss how the study of vacant habitats might ultimately inform an understanding of how life has influenced geochemical conditions on Earth. Copyright © 2010 Elsevier Ltd. All rights reserved.

Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan.

PubMed

Hwang, Ruey-Lung; Lin, Tzu-Ping; Chen, Chen-Peng; Kuo, Nai-Jung

2009-03-01

Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1-28.4 degrees C and 17.6-30.0 degrees C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7 degrees C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan

NASA Astrophysics Data System (ADS)

Hwang, Ruey-Lung; Lin, Tzu-Ping; Chen, Chen-Peng; Kuo, Nai-Jung

2009-03-01

Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1-28.4°C and 17.6-30.0°C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7°C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

Thermal conductivity characteristics of dewatered sewage sludge by thermal hydrolysis reaction.

PubMed

Song, Hyoung Woon; Park, Keum Joo; Han, Seong Kuk; Jung, Hee Suk

2014-12-01

The purpose of this study is to quantify the thermal conductivity of sewage sludge related to reaction temperature for the optimal design of a thermal hydrolysis reactor. We continuously quantified the thermal conductivity of dewatered sludge related to the reaction temperature. As the reaction temperature increased, the dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bound water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry in a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.64 times lower than that of the water at 20. However, above 200, it became 0.704 W/m* degrees C, which is about 4% higher than that of water. As a result, the change in physical properties due to thermal hydrolysis appears to be an important factor for heat transfer efficiency. Implications: The thermal conductivity of dewatered sludge is an important factor the optimal design of a thermal hydrolysis reactor. The dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. The liquid phase slurry has a higher thermal conductivity than pure water.

Identifying Time Periods of Minimal Thermal Gradient for Temperature-Driven Structural Health Monitoring.

PubMed

Reilly, John; Glisic, Branko

2018-03-01

Temperature changes play a large role in the day to day structural behavior of structures, but a smaller direct role in most contemporary Structural Health Monitoring (SHM) analyses. Temperature-Driven SHM will consider temperature as the principal driving force in SHM, relating a measurable input temperature to measurable output generalized strain (strain, curvature, etc.) and generalized displacement (deflection, rotation, etc.) to create three-dimensional signatures descriptive of the structural behavior. Identifying time periods of minimal thermal gradient provides the foundation for the formulation of the temperature-deformation-displacement model. Thermal gradients in a structure can cause curvature in multiple directions, as well as non-linear strain and stress distributions within the cross-sections, which significantly complicates data analysis and interpretation, distorts the signatures, and may lead to unreliable conclusions regarding structural behavior and condition. These adverse effects can be minimized if the signatures are evaluated at times when thermal gradients in the structure are minimal. This paper proposes two classes of methods based on the following two metrics: (i) the range of raw temperatures on the structure, and (ii) the distribution of the local thermal gradients, for identifying time periods of minimal thermal gradient on a structure with the ability to vary the tolerance of acceptable thermal gradients. The methods are tested and validated with data collected from the Streicker Bridge on campus at Princeton University.

Identifying Time Periods of Minimal Thermal Gradient for Temperature-Driven Structural Health Monitoring

PubMed Central

Reilly, John; Glisic, Branko

2018-01-01

Temperature changes play a large role in the day to day structural behavior of structures, but a smaller direct role in most contemporary Structural Health Monitoring (SHM) analyses. Temperature-Driven SHM will consider temperature as the principal driving force in SHM, relating a measurable input temperature to measurable output generalized strain (strain, curvature, etc.) and generalized displacement (deflection, rotation, etc.) to create three-dimensional signatures descriptive of the structural behavior. Identifying time periods of minimal thermal gradient provides the foundation for the formulation of the temperature–deformation–displacement model. Thermal gradients in a structure can cause curvature in multiple directions, as well as non-linear strain and stress distributions within the cross-sections, which significantly complicates data analysis and interpretation, distorts the signatures, and may lead to unreliable conclusions regarding structural behavior and condition. These adverse effects can be minimized if the signatures are evaluated at times when thermal gradients in the structure are minimal. This paper proposes two classes of methods based on the following two metrics: (i) the range of raw temperatures on the structure, and (ii) the distribution of the local thermal gradients, for identifying time periods of minimal thermal gradient on a structure with the ability to vary the tolerance of acceptable thermal gradients. The methods are tested and validated with data collected from the Streicker Bridge on campus at Princeton University. PMID:29494496

Augmentation of Solar Thermal Propulsion Systems Via Phase Change Thermal Energy Storage and Thermal Electric Conversion

DTIC Science & Technology

2012-04-01

vapor infiltration on erosion and thermal properties of porous carbon/carbon composite on thermal insulation . Carbon, (38):441– 449, 2000. [14] J. Mueller...Thermal Energy Storage and Thermal Electric Conversion 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...with thermo-acoustic instabilities. Results will be reported on the flame structure, liquid core length and spreading rate, and comparison with data

Impact of shade on outdoor thermal comfort—a seasonal field study in Tempe, Arizona

NASA Astrophysics Data System (ADS)

Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

2016-12-01

Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade and tree shade on thermal comfort through meteorological observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. During the course of 1 year, on selected clear calm days representative of each season, we conducted hourly meteorological transects from 7:00 a.m. to 6:00 p.m. and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on a semantic differential 9-point scale, increasing thermal comfort in all seasons except winter. Shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shades are equally efficient in hot dry climates. Globe temperature explained 51 % of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors included adaptation, thermal comfort vote, thermal preference, gender, season, and time of day. A regression of subjective thermal sensation on physiological equivalent temperature yielded a neutral temperature of 28.6 °C. The acceptable comfort range was 19.1 °C-38.1 °C with a preferred temperature of 20.8 °C. Respondents exposed to above neutral temperature felt more comfortable if they had been in air-conditioning 5 min prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas to reduce thermal stress.

Statistical characterization of thermal plumes in turbulent thermal convection

NASA Astrophysics Data System (ADS)

Zhou, Sheng-Qi; Xie, Yi-Chao; Sun, Chao; Xia, Ke-Qing

2016-09-01

We report an experimental study on the statistical properties of the thermal plumes in turbulent thermal convection. A method has been proposed to extract the basic characteristics of thermal plumes from temporal temperature measurement inside the convection cell. It has been found that both plume amplitude A and cap width w , in a time domain, are approximately in the log-normal distribution. In particular, the normalized most probable front width is found to be a characteristic scale of thermal plumes, which is much larger than the thermal boundary layer thickness. Over a wide range of the Rayleigh number, the statistical characterizations of the thermal fluctuations of plumes, and the turbulent background, the plume front width and plume spacing have been discussed and compared with the theoretical predictions and morphological observations. For the most part good agreements have been found with the direct observations.

Natural selection on thermal preference, critical thermal maxima and locomotor performance.

PubMed

Gilbert, Anthony L; Miles, Donald B

2017-08-16

Climate change is resulting in a radical transformation of the thermal quality of habitats across the globe. Whereas species have altered their distributions to cope with changing environments, the evidence for adaptation in response to rising temperatures is limited. However, to determine the potential of adaptation in response to thermal variation, we need estimates of the magnitude and direction of natural selection on traits that are assumed to increase persistence in warmer environments. Most inferences regarding physiological adaptation are based on interspecific analyses, and those of selection on thermal traits are scarce. Here, we estimate natural selection on major thermal traits used to assess the vulnerability of ectothermic organisms to altered thermal niches. We detected significant directional selection favouring lizards with higher thermal preferences and faster sprint performance at their optimal temperature. Our analyses also revealed correlational selection between thermal preference and critical thermal maxima, where individuals that preferred warmer body temperatures with cooler critical thermal maxima were favoured by selection. Recent published estimates of heritability for thermal traits suggest that, in concert with the strong selective pressures we demonstrate here, evolutionary adaptation may promote long-term persistence of ectotherms in altered thermal environments. © 2017 The Author(s).

Estimating Thermal Inertia with a Maximum Entropy Boundary Condition

NASA Astrophysics Data System (ADS)

Nearing, G.; Moran, M. S.; Scott, R.; Ponce-Campos, G.

2012-04-01

superior thermal inertia estimates. The MEP-diffusion estimates also agreed well with P estimates made using a boundary condition measured with buried flux plates. We further demonstrated the new method using diurnal surface temperature fluctuations estimated from day/night MODIS image pairs and, excluding instances where the soil was extremely dry, found a strong relationship between estimated thermal inertia and measured 5 cm soil moisture. Lu, S., Ju, Z.Q., Ren, T.S. & Horton, R. (2009). A general approach to estimate soil water content from thermal inertia. Agricultural and Forest Meteorology, 149, 1693-1698. Murray, T. & Verhoef, A. (2007). Moving towards a more mechanistic approach in the determination of soil heat flux from remote measurements - I. A universal approach to calculate thermal inertia. Agricultural and Forest Meteorology, 147, 80-87. Wang, J.F. & Bras, R.L. (2011). A model of evapotranspiration based on the theory of maximum entropy production. Water Resources Research, 47. Xue, Y. & Cracknell, A.P. (1995). Advanced thermal inertia modeling. International Journal of Remote Sensing, 16, 431-446.

Thermal comfort assessment in Moscow during the summer 2010

NASA Astrophysics Data System (ADS)

Malinina, Elizaveta; Konstantinov, Pavel

2013-04-01

Biometeorological indices are used to asses thermal comfort conditions and evaluate the influence of the weather on the human organism and health. Despite of the fact, that some biometeorological indices are already used in weather forecast, the assessment of these indices is especially important during the extreme weather conditions like continuous heat or cold waves. One of the very urgent issues in the applied climatology is the assessment of thermal comfort conditions in the urban areas, because nowadays more than half population of the planet lives there. Especially important is to study thermal comfort conditions in biggest and, thus, densely populated cities, because the effect of heat waves becomes stronger by the urban heat island effect. In July and August 2010 in the biggest city in Russia - Moscow, where more than 11 million people live, the longest and the strongest heat wave as well as the warmest day (29th of July 2010) were recorded since the meteorological observations in Russian capital were started. The main objective of this work is to evaluate the thermal comfort conditions of the warmest day in Moscow. For that purpose several biometeorological indices, particularly PET (physiological equivalent temperature), were analyzed and calculated for the warmest day in Russian capital. The calculations were done for the certain city canyon on the territory of the Moscow State University as well as for the places with natural vegetation. The results were compared with each other and, thus, the complex thermal comfort assessment was done. Also, the results of the calculations for the 29th of July 2010 were compared with the mean meteorological data for this period.

Electronic thermal conductivity and the Wiedemann-Franz law for unconventional superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graf, M.J.; Yip, S.; Sauls, J.A.

1996-06-01

We use the quasiclassical theory of superconductivity to calculate the electronic contribution to the thermal conductivity. The theory is formulated for low temperatures when heat transport is limited by electron scattering from random defects and for superconductors with nodes in the order parameter. We show that certain eigenvalues of the thermal conductivity tensor are universal at low temperature, {ital k}{sub {ital BT}}{lt}{gamma}, where {gamma} is the bandwidth of impurity bound states in the superconducting phase. The components of the electrical and thermal conductivity also obey a Wiedemann-Franz law with the Lorenz ratio {ital L}({ital T})={kappa}/{sigma}{ital T} given by the Sommerfeldmore » value of {ital L}{sub {ital S}}=({pi}{sup 2}/3)({ital k}{sub {ital B}}/{ital e}){sup 2} for {ital k}{sub {ital BT}}{lt}{gamma}. For intermediate temperatures the Lorenz ratio deviates significantly from {ital L}{sub {ital S}}, and is strongly dependent on the scattering cross section, and qualitatively different for resonant vs nonresonant scattering. We include comparisons with other theoretical calculations and the thermal conductivity data for the high-{ital T}{sub {ital c}} cuprate and heavy fermion superconductors. {copyright} {ital 1996 The American Physical Society.}« less

Application of remote sensing to thermal pollution analysis. [satellite sea surface temperature measurement assessment

NASA Technical Reports Server (NTRS)

Hiser, H. W.; Lee, S. S.; Veziroglu, T. N.; Sengupta, S.

1975-01-01

A comprehensive numerical model development program for near-field thermal plume discharge and far field general circulation in coastal regions is being carried on at the University of Miami Clean Energy Research Institute. The objective of the program is to develop a generalized, three-dimensional, predictive model for thermal pollution studies. Two regions of specific application of the model are the power plants sites at the Biscayne Bay and Hutchinson Island area along the Florida coastline. Remote sensing from aircraft as well as satellites are used in parallel with in situ measurements to provide information needed for the development and verification of the mathematical model. This paper describes the efforts that have been made to identify problems and limitations of the presently available satellite data and to develop methods for enhancing and enlarging thermal infrared displays for mesoscale sea surface temperature measurements.

Extending the applied software in the contemporary thermal power plants for increasing the intelligence of the automatic control system

NASA Astrophysics Data System (ADS)

Krokhin, G.; Pestunov, A.; Arakelyan, E.; Mukhin, V.

2017-11-01

During the last decades, there can be noticed an increase of interest concerning various aspects of intellectual diagnostics and management in thermal power engineering according the hybrid principle. It is conditioned by the fact that conservative static methods does not allow to reflect the actual power installation state adequately. In order to improve the diagnostics quality, we use various fuzzy systems apparatus. In this paper, we introduce the intellectual system, called SKAIS, which is intended for quick and precise diagnostics of thermal power equipment. This system was developed as the result of the research carried out by specialists from National Research University “Moscow Power Engineering Institute” and Novosibirsk State University of Economics and Management. It drastically increases the level of intelligence of the automatic power plant control system.

The Effect of Core Configuration on Thermal Barrier Thermal Performance

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J.; Bott, Robert H.; Druesedow, Anne S.

2015-01-01

Thermal barriers and seals are integral components in the thermal protection systems (TPS) of nearly all aerospace vehicles. They are used to minimize heat transfer through interfaces and gaps and protect underlying temperature-sensitive components. The core insulation has a significant impact on both the thermal and mechanical properties of compliant thermal barriers. Proper selection of an appropriate core configuration to mitigate conductive, convective and radiative heat transfer through the thermal barrier is challenging. Additionally, optimization of the thermal barrier for thermal performance may have counteracting effects on mechanical performance. Experimental evaluations have been conducted to better understand the effect of insulation density on permeability and leakage performance, which can significantly impact the resistance to convective heat transfer. The effect of core density on mechanical performance was also previously investigated and will be reviewed. Simple thermal models were also developed to determine the impact of various core parameters on downstream temperatures. An extended understanding of these factors can improve the ability to design and implement these critical TPS components.

Nano-Localized Thermal Analysis and Mapping of Surface and Sub-Surface Thermal Properties Using Scanning Thermal Microscopy (SThM).

PubMed

Pereira, Maria J; Amaral, Joao S; Silva, Nuno J O; Amaral, Vitor S

2016-12-01

Determining and acting on thermo-physical properties at the nanoscale is essential for understanding/managing heat distribution in micro/nanostructured materials and miniaturized devices. Adequate thermal nano-characterization techniques are required to address thermal issues compromising device performance. Scanning thermal microscopy (SThM) is a probing and acting technique based on atomic force microscopy using a nano-probe designed to act as a thermometer and resistive heater, achieving high spatial resolution. Enabling direct observation and mapping of thermal properties such as thermal conductivity, SThM is becoming a powerful tool with a critical role in several fields, from material science to device thermal management. We present an overview of the different thermal probes, followed by the contribution of SThM in three currently significant research topics. First, in thermal conductivity contrast studies of graphene monolayers deposited on different substrates, SThM proves itself a reliable technique to clarify the intriguing thermal properties of graphene, which is considered an important contributor to improve the performance of downscaled devices and materials. Second, SThM's ability to perform sub-surface imaging is highlighted by thermal conductivity contrast analysis of polymeric composites. Finally, an approach to induce and study local structural transitions in ferromagnetic shape memory alloy Ni-Mn-Ga thin films using localized nano-thermal analysis is presented.

DEVELOPMENT OF ISOTOPICALLY ENRICHED BORON-DOPED ALUMINA DOSIMETER FOR THERMAL NEUTRONS.

PubMed

Sato, Fuminobu; Maekawa, Tatsuro; Kariba, Tomoharu; Kusaka, Sachie; Tanaka, Teruya; Murata, Isao

2017-12-01

A novel optically stimulated luminescence (OSL) detector containing isotopically enriched boron was developed for thermal neutron dosimetry. Alumina containing isotopically enriched boron (Al2O3:B) was synthesised by the sol-gel method. The Al2O3:B was annealed up to ~1800 K. For X-ray diffractometer (XRD) analysis, the diffraction pattern of the Al2O3:B had reflex peaks corresponding to α-Al2O3. The sensitivity of Al2O3:B to photons was slightly 2% of that of a commercial Al2O3:C. The Al2O3:B detector had satisfactory linearity in X-ray dose measurement. A thermal neutron field was constructed using a 241Am-Be neutron source and graphite blocks. A pair of Al2O3:10B and Al2O3:11B detectors were set in the thermal neutron field. The response of Al2O3:10B was larger than that of Al2O3:11B owing to the 10B(n,α)7Li reactions. The sensitivity of Al2O3:10B to thermal neutrons was estimated to be two orders less than the photon sensitivity. Therefore, the pair of Al2O3:10B and Al2O3:11B detectors were useful for thermal neutron dosimetry. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Scalable Fabrication Process for Liquid Crystal Based Uncooled Thermal Imagers

DTIC Science & Technology

2016-02-12

ll.mit.edu). Phillip Bos, Valerie Finnemeyer, Colin McGinty and Douglas Bryant are with the Liquid Crystal Institute at Kent State University, Kent...Crystal-Based Uncooled Thermal Imagers Shaun Berry, Carl Bozler, Robert Reich, Harry Clark Jr., Phillip Bos, Valerie Finnemeyer, Colin McGinty...was aligned to the die features on the wafer with appropriate weight added (Fig. 5b). We used stainless steel bars to apply the weight to the block

Bioclimatic comfort and the thermal perceptions and preferences of beach tourists.

PubMed

Rutty, Michelle; Scott, Daniel

2015-01-01

The largest market segment of global tourism is coastal tourism, which is strongly dependent on the destination's thermal climate. To date, outdoor bioclimatic comfort assessments have focused exclusively on local residents in open urban areas, making it unclear whether outdoor comfort is perceived differently in non-urban environments or by non-residents (i.e. tourists) with different weather expectations and activity patterns. This study provides needed insight into the perception of outdoor microclimatic conditions in a coastal environment while simultaneously identifying important psychological factors that differentiate tourists from everyday users of urban spaces. Concurrent micrometeorological measurements were taken on several Caribbean beaches in the islands of Barbados, Saint Lucia and Tobago, while a questionnaire survey was used to examine the thermal comfort of subjects (n = 472). Universal Thermal Climate Index (UTCI) conditions of 32 to 39 °C were recorded, which were perceived as being "slightly warm" or "warm" by respondents. Most beach users (48 to 77 %) would not change the thermal conditions, with some (4 to 15 %) preferring even warmer conditions. Even at UTCI of 39 °C, 62 % of respondents voted for no change to current thermal conditions, with an additional 10 % stating that they would like to feel even warmer. These results indicate that beach users' thermal preferences are up to 18 °C warmer than the preferred thermal conditions identified in existing outdoor bioclimatic studies from urban park settings. This indicates that beach users hold fundamentally different comfort perceptions and preferences compared to people using urban spaces. Statistically significant differences (p ≤ .05) were also recorded for demographic groups (gender, age) and place of origin (climatic region).

Investigation of thermal fatigue in fiber composite materials. [(thermal cycling tests)

NASA Technical Reports Server (NTRS)

Fahmy, A. A.; Cunningham, T. G.

1976-01-01

Graphite-epoxy laminates were thermally cycled to determine the effects of thermal cycles on tensile properties and thermal expansion coefficients of the laminates. Three 12-ply laminate configurations were subjected to up to 5,000 thermal cycles. The cumulative effect of the thermal cycles was determined by destructive inspection (electron micrographs and tensile tests) of samples after progressively larger numbers of cycles. After thermal cycling, the materials' tensile strengths, moduli, and thermal expansion coefficients were significantly lower than for the materials as fabricated. Most of the degradation of properties occurred after only a few cycles. The property degradation was attributed primarily to the progressive development of matrix cracks whose locations depended upon the layup orientation of the laminate.

Thermal Analysis of Thermal Protection System of Test Launch Vehicle

NASA Astrophysics Data System (ADS)

Kim, Jongmin

2017-10-01

In this paper, a thermal analysis of the thermal protection system (TPS) of test launch vehicle (TLV) is explained. TLV is heated during the flight due to engine exhaust plume gas by thermal radiation and a TPS is needed to protect the vehicle from the heating. The thermal analysis of the TPS is conducted to predict the heat flux from plume gas and temperature of the TPS during the flight. To simplify the thermal analysis, plume gas radiation and radiative properties are assumed to be surface radiation and constants, respectively. Thermal conductivity, emissivity and absorptivity of the TPS material are measured. Proper plume conditions are determined from the preliminary analysis and then the heat flux and temperature of the TPS are calculated.

Thermal mechanical analysis of applications with internal heat generation

NASA Astrophysics Data System (ADS)

Govindarajan, Srisharan Garg

The radioactive tracer Technetium-99m is widely used in medical imaging and is derived from its parent isotope Molybedenum-99 (Mo-99) by radioactive decay. The majority of Molybdenum-99 (Mo-99) produced internationally is extracted from high enriched uranium (HEU) dispersion targets that have been irradiated. To alleviate proliferation risks associated with HEU-based targets, the use of non-HEU sources is being mandated. However, the conversion of HEU to LEU based dispersion targets affects the Mo-99 available for chemical extraction. A possible approach to increase the uranium density, to recover the loss in Mo-99 production-per-target, is to use an LEU metal foil placed within an aluminum cladding to form a composite structure. The target is expected to contain the fission products and to dissipate the generated heat to the reactor coolant. In the event of interfacial separation, an increase in the thermal resistance could lead to an unacceptable rise in the LEU temperature and stresses in the target. The target can be deemed structurally safe as long as the thermally induced stresses are within the yield strength of the cladding and welds. As with the thermal and structural safety of the annular target, the thermally induced deflection of the BORALRTM-based control blades, used by the University of Missouri Research Reactor (MURRRTM ), during reactor operation has been analyzed. The boron, which is the neutron absorber in BORAL, and aluminum mixture (BORAL meat) and the aluminum cladding are bonded together through powder metallurgy to establish an adherent bonded plate. As the BORAL absorbs both neutron particles and gamma rays, there is volumetric heat generation and a corresponding rise in temperature. Since the BORAL meat and aluminum cladding materials have different thermal expansion coefficients, the blade may have a tendency to deform as the blade temperature changes and the materials expand at different rates. In addition to the composite nature of the

Development of Innovative Accident Tolerant High Thermal Conductivity UO 2-Diamond Composite Fuel Pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tulenko, James; Subhash, Ghatu

2016-01-01

The University of Florida (UF) evaluated a composite fuel consisting of UO 2 powder mixed with diamond micro particles as a candidate as an accident-tolerant fuel (ATF). The research group had previous extensive experience researching with diamond micro particles as an addition to reactor coolant for improved plant thermal performance. The purpose of this research work was to utilize diamond micro particles to develop UO 2-Diamond composite fuel pellets with significantly enhanced thermal properties, beyond that already being measured in the previous UF research projects of UO 2 – SiC and UO 2 – Carbon Nanotube fuel pins. UF ismore » proving with the current research results that the addition of diamond micro particles to UO 2 may greatly enhanced the thermal conductivity of the UO 2 pellets producing an accident-tolerant fuel. The Beginning of life benefits have been proven and fuel samples are being irradiated in the ATR reactor to confirm that the thermal conductivity improvements are still present under irradiation.« less

Graphene nanoplatelets: Thermal diffusivity and thermal conductivity by the flash method

NASA Astrophysics Data System (ADS)

Potenza, M.; Cataldo, A.; Bovesecchi, G.; Corasaniti, S.; Coppa, P.; Bellucci, S.

2017-07-01

The present work deals with the measurement of thermo-physical properties of a freestanding sheet of graphene (thermal diffusivity and thermal conductivity), and their dependence on sample density as result of uniform mechanical compression. Thermal diffusivity of graphene nano-platelets (thin slabs) was measured by the pulse flash method. Obtained response data were processed with a specifically developed least square data processing algorithm. GNP specific heat was assumed from literature and thermal conductivity derived from thermal diffusivity, specific heat and density. Obtained results show a significant difference with respect to other porous media: the thermal diffusivity decreases as the density increases, while thermal conductivity increases for low and high densities, and remain fairly constant for the intermediate range. This can be explained by the very high thermal conductivity values reached by the nano-layers of graphene and the peculiar arrangement of platelets during the compression applied to the samples to get the desired density. Due to very high thermal conductivity of graphene layers, the obtained results show that thermal conductivity of conglomerates increases when there is an air reduction due to compression, and consequent density increases, with the number of contact points between platelets also increased. In the intermediate range (250 ≤ ρ ≤ 700 kg.m-3) the folding of platelets reduces density, without increasing the contact points of platelets, so thermal conductivity can slightly decrease.

Spacecraft Thermal Control

NASA Technical Reports Server (NTRS)

Birur, Gajanana C.; Siebes, Georg; Swanson, Theodore D.; Powers, Edward I. (Technical Monitor)

2001-01-01

Thermal control of the spacecraft is typically achieved by removing heat from the spacecraft parts that tend to overheat and adding heat to the parts that tend get too cold. The equipment on the spacecraft can get very hot if it is exposed to the sun or have internal heat generation. The pans also can get very cold if they are exposed to the cold of deep space. The spacecraft and instruments must be designed to achieve proper thermal balance. The combination of the spacecraft's external thermal environment, its internal heat generation (i.e., waste heat from the operation of electrical equipment), and radiative heat rejection will determine this thermal balance. It should also be noted that this is seldom a static situation, external environmental influences and internal heat generation are normally dynamic variables which change with time. Topics discussed include thermal control system components, spacecraft mission categories, spacecraft thermal requirements, space thermal environments, thermal control hardware, launch and flight operations, advanced technologies for future spacecraft,

Status of rates and rate equations for thermal leptogenesis

NASA Astrophysics Data System (ADS)

Biondini, S.; Bödeker, D.; Brambilla, N.; Garny, M.; Ghiglieri, J.; Hohenegger, A.; Laine, M.; Mendizabal, S.; Millington, P.; Salvio, A.; Vairo, A.

2018-02-01

In many realizations of leptogenesis, heavy right-handed neutrinos play the main role in the generation of an imbalance between matter and antimatter in the early Universe. Hence, it is relevant to address quantitatively their dynamics in a hot and dense environment by taking into account the various thermal aspects of the problem at hand. The strong washout regime offers an interesting framework to carry out calculations systematically and reduce theoretical uncertainties. Indeed, any matter-antimatter asymmetry generated when the temperature of the hot plasma T exceeds the right-handed neutrino mass scale M is efficiently erased, and one can focus on the temperature window T ≪ M. We review recent progress in the thermal field theoretic derivation of the key ingredients for the leptogenesis mechanism: the right-handed neutrino production rate, the CP asymmetry in the heavy-neutrino decays and the washout rates. The derivation of evolution equations for the heavy-neutrino and lepton-asymmetry number densities, their rigorous formulation and applicability are also discussed.

Transient thermal analysis of a titanium multiwall thermal protection system

NASA Technical Reports Server (NTRS)

Blosser, M. L.

1982-01-01

The application of the SPAR thermal analyzer to the thermal analysis of a thermal protection system concept is discussed. The titanium multiwall thermal protection system concept consists of alternate flat and dimpled sheets which are joined together at the crests of the dimples and formed into 30 cm by 30 cm (12 in. by 12 in.) tiles. The tiles are mechanically attached to the structure. The complex tile geometry complicates thermal analysis. Three modes of heat transfer were considered: conduction through the gas inside the tile, conduction through the metal, and radiation between the various layers. The voids between the dimpled and flat sheets were designed to be small enough so that natural convection is insignificant (e.g., Grashof number 1000). A two step approach was used in the thermal analysis of the multiwall thermal protection system. First, an effective normal (through-the-thickness) thermal conductivity was obtained from a steady state analysis using a detailed SPAR finite element model of a small symmetric section of the multiwall tile. This effective conductivity was then used in simple one dimensional finite element models for preliminary analysis of several transient heat transfer problems.

Milder form of heat-related symptoms and thermal sensation: a study in a Mediterranean climate

NASA Astrophysics Data System (ADS)

Pantavou, Katerina G.; Lykoudis, Spyridon P.; Nikolopoulos, Georgios K.

2016-06-01

Mild heat-related health effects and their potential association with meteorological and personal parameters in relation to subjective and objective thermal sensation were investigated. Micrometeorological measurements and questionnaire surveys were conducted in an urban Mediterranean environment during a warm, cool, and a transitional season. The participants were asked to indicate their thermal sensation based on a seven-point scale and report whether they were experiencing any of the following symptoms: headache, dizziness, breathing difficulties, and exhaustion. Two thermal indices, Actual Sensation Vote (ASV) and Universal Thermal Climate Index (UTCI), were estimated in order to obtain an objective measure of individuals' thermal sensation. Binary logistic regression was applied to identify risk parameters while cluster analysis was used to determine thresholds of air temperature, ASV and UTCI related to health effects. Exhaustion was the most frequent symptom reported by the interviewees. Females and smokers were more likely to report heat-related symptoms than males and nonsmokers. Based on cluster analysis, 35 °C could be a cutoff point for the manifestation of heat-related symptoms during summer. The threshold for ASV was 0.85 corresponding to "warm" thermal sensation and for UTCI was about 30.85 °C corresponding to "moderate heat stress" according to the Mediterranean assessment scale.

Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

PubMed

Günay, A Alperen; Kim, Hannah; Nagarajan, Naveen; Lopez, Mateusz; Kantharaj, Rajath; Alsaati, Albraa; Marconnet, Amy; Lenert, Andrej; Miljkovic, Nenad

2018-04-18

Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

Does oxygen limit thermal tolerance in arthropods? A critical review of current evidence

PubMed Central

Verberk, Wilco C.E.P.; Overgaard, Johannes; Ern, Rasmus; Bayley, Mark; Wang, Tobias; Boardman, Leigh; Terblanche, John S.

2016-01-01

Over the last decade, numerous studies have investigated the role of oxygen in setting thermal tolerance in aquatic animals, and there has been particular focus on arthropods. Arthropods comprise one of the most species-rich taxonomic groups on Earth, and display great diversity in the modes of ventilation, circulation, blood oxygen transport, with representatives living both in water (mainly crustaceans) and on land (mainly insects). The oxygen and capacity limitation of thermal tolerance (OCLTT) hypothesis proposes that the temperature dependent performance curve of animals is shaped by the capacity for oxygen delivery in relation to oxygen demand. If correct, oxygen limitation could provide a mechanistic framework to understand and predict both current and future impacts of rapidly changing climate. In arthropods, most studies testing the OCLTT hypothesis have considered tolerance to thermal extremes. These studies likely operate from the philosophical viewpoint that if the model can predict these critical thermal limits, then it is more likely to also explain loss of performance at less extreme, non-lethal temperatures, for which much less data is available. Nevertheless, the extent to which lethal temperatures are influenced by limitations in oxygen supply remains unresolved. Here we critically evaluate the support and universal applicability for oxygen limitation being involved in lethal temperatures in crustaceans and insects. The relatively few studies investigating the OCLTT hypothesis at low temperature do not support a universal role for oxygen in setting the lower thermal limits in arthropods. With respect to upper thermal limits, the evidence supporting OCLTT is stronger for species relying on underwater gas exchange, while the support for OCLTT in air-breathers is weak. Overall, strongest support was found for increased anaerobic metabolism close to thermal maxima. In contrast, there was only mixed support for the prediction that aerobic scope

Thermal Performance Benchmarking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Xuhui; Moreno, Gilbert; Bennion, Kevin

2016-06-07

The goal for this project is to thoroughly characterize the thermal performance of state-of-the-art (SOA) in-production automotive power electronics and electric motor thermal management systems. Information obtained from these studies will be used to: evaluate advantages and disadvantages of different thermal management strategies; establish baseline metrics for the thermal management systems; identify methods of improvement to advance the SOA; increase the publicly available information related to automotive traction-drive thermal management systems; help guide future electric drive technologies (EDT) research and development (R&D) efforts. The thermal performance results combined with component efficiency and heat generation information obtained by Oak Ridge Nationalmore » Laboratory (ORNL) may then be used to determine the operating temperatures for the EDT components under drive-cycle conditions. In FY16, the 2012 Nissan LEAF power electronics and 2014 Honda Accord Hybrid power electronics thermal management system were characterized. Comparison of the two power electronics thermal management systems was also conducted to provide insight into the various cooling strategies to understand the current SOA in thermal management for automotive power electronics and electric motors.« less

Industrial application of thermal image processing and thermal control

NASA Astrophysics Data System (ADS)

Kong, Lingxue

2001-09-01

Industrial application of infrared thermography is virtually boundless as it can be used in any situations where there are temperature differences. This technology has particularly been widely used in automotive industry for process evaluation and system design. In this work, thermal image processing technique will be introduced to quantitatively calculate the heat stored in a warm/hot object and consequently, a thermal control system will be proposed to accurately and actively manage the thermal distribution within the object in accordance with the heat calculated from the thermal images.

Impact of shade on outdoor thermal comfort-a seasonal field study in Tempe, Arizona.

PubMed

Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

2016-12-01

Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade and tree shade on thermal comfort through meteorological observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. During the course of 1 year, on selected clear calm days representative of each season, we conducted hourly meteorological transects from 7:00 a.m. to 6:00 p.m. and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on a semantic differential 9-point scale, increasing thermal comfort in all seasons except winter. Shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shades are equally efficient in hot dry climates. Globe temperature explained 51 % of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors included adaptation, thermal comfort vote, thermal preference, gender, season, and time of day. A regression of subjective thermal sensation on physiological equivalent temperature yielded a neutral temperature of 28.6 °C. The acceptable comfort range was 19.1 °C-38.1 °C with a preferred temperature of 20.8 °C. Respondents exposed to above neutral temperature felt more comfortable if they had been in air-conditioning 5 min prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas to reduce thermal stress.

Ultra-high thermal effusivity materials for resonant ambient thermal energy harvesting.

PubMed

Cottrill, Anton L; Liu, Albert Tianxiang; Kunai, Yuichiro; Koman, Volodymyr B; Kaplan, Amir; Mahajan, Sayalee G; Liu, Pingwei; Toland, Aubrey R; Strano, Michael S

2018-02-14

Materials science has made progress in maximizing or minimizing the thermal conductivity of materials; however, the thermal effusivity-related to the product of conductivity and capacity-has received limited attention, despite its importance in the coupling of thermal energy to the environment. Herein, we design materials that maximize the thermal effusivity by impregnating copper and nickel foams with conformal, chemical-vapor-deposited graphene and octadecane as a phase change material. These materials are ideal for ambient energy harvesting in the form of what we call thermal resonators to generate persistent electrical power from thermal fluctuations over large ranges of frequencies. Theory and experiment demonstrate that the harvestable power for these devices is proportional to the thermal effusivity of the dominant thermal mass. To illustrate, we measure persistent energy harvesting from diurnal frequencies, extracting as high as 350 mV and 1.3 mW from approximately 10 °C diurnal temperature differences.

Temperature-dependent thermal properties of ex vivo liver undergoing thermal ablation.

PubMed

Guntur, Sitaramanjaneya Reddy; Lee, Kang Il; Paeng, Dong-Guk; Coleman, Andrew John; Choi, Min Joo

2013-10-01

Thermotherapy uses a heat source that raises temperatures in the target tissue, and the temperature rise depends on the thermal properties of the tissue. Little is known about the temperature-dependent thermal properties of tissue, which prevents us from accurately predicting the temperature distribution of the target tissue undergoing thermotherapy. The present study reports the key thermal parameters (specific heat capacity, thermal conductivity and heat diffusivity) measured in ex vivo porcine liver while being heated from 20 ° C to 90 ° C and then naturally cooled down to 20 ° C. The study indicates that as the tissue was heated, all the thermal parameters resulted in plots with asymmetric quasi-parabolic curves with temperature, being convex downward with their minima at the turning temperature of 35-40 ° C. The largest change was observed for thermal conductivity, which decreased by 9.6% from its initial value (at 20 ° C) at the turning temperature (35 ° C) and rose by 45% at 90 ° C from its minimum (at 35 ° C). The minima were 3.567 mJ/(m(3) ∙ K) for specific heat capacity, 0.520 W/(m.K) for thermal conductivity and 0.141 mm(2)/s for thermal diffusivity. The minimum at the turning temperature was unique, and it is suggested that it be taken as a characteristic value of the thermal parameter of the tissue. On the other hand, the thermal parameters were insensitive to temperature and remained almost unchanged when the tissue cooled down, indicating that their variations with temperature were irreversible. The rate of the irreversible rise at 35 ° C was 18% in specific heat capacity, 40% in thermal conductivity and 38.3% in thermal diffusivity. The study indicates that the key thermal parameters of ex vivo porcine liver vary largely with temperature when heated, as described by asymmetric quasi-parabolic curves of the thermal parameters with temperature, and therefore, substantial influence on the temperature distribution of the tissue undergoing

Quantum Thermal Transistor.

PubMed

Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose

2016-05-20

We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems.

Recapturing the Universal in the University

ERIC Educational Resources Information Center

Barnett, Ronald

2005-01-01

The idea of "the university" has stood for universal themes--of knowing, of truthfulness, of learning, of human development, and of critical reason. Through its affirming and sustaining of such themes, the university came itself to stand for universality in at least two senses: the university was neither partial (in its truth criteria) nor local…

Fluctuation-driven electroweak phase transition. [in early universe

NASA Technical Reports Server (NTRS)

Gleiser, Marcelo; Kolb, Edward W.

1992-01-01

We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.

Sex differences in thermal detection and thermal pain threshold and the thermal grill illusion: a psychophysical study in young volunteers.

PubMed

Averbeck, Beate; Seitz, Lena; Kolb, Florian P; Kutz, Dieter F

2017-09-01

Sex-related differences in human thermal and pain sensitivity are the subject of controversial discussion. The goal of this study in a large number of subjects was to investigate sex differences in thermal and thermal pain perception and the thermal grill illusion (TGI) as a phenomenon reflecting crosstalk between the thermoreceptive and nociceptive systems. The thermal grill illusion is a sensation of strong, but not necessarily painful, heat often preceded by transient cold upon skin contact with spatially interlaced innocuous warm and cool stimuli. The TGI was studied in a group of 78 female and 58 male undergraduate students and was evoked by placing the palm of the right hand on the thermal grill (20/40 °C interleaved stimulus). Sex-related thermal perception was investigated by a retrospective analysis of thermal detection and thermal pain threshold data that had been measured in student laboratory courses over 5 years (776 female and 476 male undergraduate students) using the method of quantitative sensory testing (QST). To analyse correlations between thermal pain sensitivity and the TGI, thermal pain threshold and the TGI were determined in a group of 20 female and 20 male undergraduate students. The TGI was more pronounced in females than males. Females were more sensitive with respect to thermal detection and thermal pain thresholds. Independent of sex, thermal detection thresholds were dependent on the baseline temperature with a specific progression of an optimum curve for cold detection threshold versus baseline temperature. The distribution of cold pain thresholds was multi-modal and sex-dependent. The more pronounced TGI in females correlated with higher cold sensitivity and cold pain sensitivity in females than in males. Our finding that thermal detection threshold not only differs between the sexes but is also dependent on the baseline temperature reveals a complex processing of "cold" and "warm" inputs in thermal perception. The results of the

UTCI—Why another thermal index?

NASA Astrophysics Data System (ADS)

Jendritzky, Gerd; de Dear, Richard; Havenith, George

2012-05-01

Existing procedures for the assessment of the thermal environment in the fields of public weather services, public health systems, precautionary planning, urban design, tourism and recreation and climate impact research exhibit significant shortcomings. This is most evident for simple (mostly two-parameter) indices, when comparing them to complete heat budget models developed since the 1960s. ISB Commission 6 took up the idea of developing a Universal Thermal Climate Index (UTCI) based on the most advanced multi-node model of thermoregulation representing progress in science within the last three to four decades, both in thermo-physiological and heat exchange theory. Creating the essential research synergies for the development of UTCI required pooling the resources of multidisciplinary experts in the fields of thermal physiology, mathematical modelling, occupational medicine, meteorological data handling (in particular radiation modelling) and application development in a network. It was possible to extend the expertise of ISB Commission 6 substantially by COST (a European programme promoting Cooperation in Science and Technology) Action 730 so that finally over 45 scientists from 23 countries (Australia, Canada, Israel, several Europe countries, New Zealand, and the United States) worked together. The work was performed under the umbrella of the WMO Commission on Climatology (CCl). After extensive evaluations, Fiala's multi-node human physiology and thermal comfort model (FPC) was adopted for this study. The model was validated extensively, applying as yet unused data from other research groups, and extended for the purposes of the project. This model was coupled with a state-of-the-art clothing model taking into consideration behavioural adaptation of clothing insulation by the general urban population in response to actual environmental temperature. UTCI was then derived conceptually as an equivalent temperature (ET). Thus, for any combination of air

Research on controlling thermal deformable mirror's influence functions via manipulating thermal fields.

PubMed

Xue, Qiao; Huang, Lei; Hu, Dongxia; Yan, Ping; Gong, Mali

2014-01-10

For thermal deformable mirrors (DMs), the thermal field control is important because it will decide aberration correction effects. In order to better manipulate the thermal fields, a simple water convection system is proposed. The water convection system, which can be applied in thermal field bimetal DMs, shows effective thermal fields and influence-function controlling abilities. This is verified by the simulations and the contrast experiments of two prototypes: one of which utilizes air convection, the other uses water convection. Controlling the thermal fields will greatly promote the influence-function adjustability and aberration correction ability of thermal DMs.

Thermal Writing 1987

NASA Astrophysics Data System (ADS)

Peckham, Robert F.

1987-04-01

The creating of intelligent marks on a substrate by means of thermal energy has been in use for thousands of years, e.g., branding of livestock and burning images onto wood. During the past 30 years, this type of imaging has been significantly refined. Recent advances allow the creation of color images, 16 shades of gray and letter quality printing on white substrates. Permanent images are now being written with direct thermal processes. The foregoing make thermal writing very attractive for numerous applications. The general technology of how thermal writing is accomplished today, its applications, and why society should use thermal writing are the topics of this paper. To attempt to cover in great technical detail all of the current advancements in thermal writing is beyond our scope here. What is intended is the proposition that THERMAL WRITING is a superior form of creating images on paper substrates for Society's on demand hard copy requirements. First let's look at how thermal writing is being accomplished with today's technologies.

Outdoor thermal comfort.

PubMed

Nikolopoulou, Marialena

2011-06-01

A review of the various approaches in understanding outdoor thermal comfort is presented. The emphasis on field surveys from around the world, particularly across Europe, enables us to understand thermal perception and evaluate outdoor thermal comfort conditions. The consistent low correlations between objective microclimatic variables, subjective thermal sensation and comfort outdoors, internationally, suggest that thermophysiology alone does not adequate describe these relationships. Focusing on the concept of adaptation, it tries to explain how this influences outdoor comfort, enabling us to inhabit and get satisfaction from outdoor spaces throughout the year. Beyond acclimatization and behavioral adaptation, through adjustments in clothing and changes to the metabolic heat, psychological adaptation plays a critical role to ensure thermal comfort and satisfaction with the outdoor environment. Such parameters include recent experiences and expectations; personal choice and perceived control, more important than whether that control is actually exercised; and the need for positive environmental stimulation suggesting that thermal neutrality is not a pre-requisite for thermal comfort. Ultimately, enhancing environmental diversity can influence thermal perception and experience of open spaces.

NASA Goddard Thermal Technology Overview 2017

NASA Technical Reports Server (NTRS)

Butler, Dan; Swanson, Ted

2017-01-01

This presentation summarizes the current plans and efforts at NASA Goddard to develop new thermal control technology for anticipated future missions. It will also address some of the programmatic developments currently underway at NASA, especially with respect to the NASA Technology Development Program. The effects of the recently enacted FY 17 NASA budget, which includes a sizeable increase, will also be addressed. While funding for basic technology development is still tight, significant efforts are being made in direct support of flight programs. Thermal technology Implementation on current flight programs will be reviewed, and the recent push for CubeSat mission development will also be addressed. Many of these technologies also have broad applicability to DOD (Dept. of Defense), DOE (Dept. of the Environment), and commercial programs. Partnerships have been developed with the Air Force, Navy, and various universities to promote technology development. In addition, technology development activities supported by internal research and development (IRAD) program and the Small Business Innovative Research (SBIR) program are reviewed in this presentation. Specific technologies addressed include; two-phase systems applications and issues on NASA missions, latest developments of electro-hydrodynamically pumped systems, Atomic Layer Deposition (ALD), Micro-scale Heat Transfer, and various other research activities.

Wide-range measurement of thermal effusivity using molybdenum thin film with low thermal conductivity for thermal microscopes

NASA Astrophysics Data System (ADS)

Miyake, Shugo; Matsui, Genzou; Ohta, Hiromichi; Hatori, Kimihito; Taguchi, Kohei; Yamamoto, Suguru

2017-07-01

Thermal microscopes are a useful technology to investigate the spatial distribution of the thermal transport properties of various materials. However, for high thermal effusivity materials, the estimated values of thermophysical parameters based on the conventional 1D heat flow model are known to be higher than the values of materials in the literature. Here, we present a new procedure to solve the problem which calculates the theoretical temperature response with the 3D heat flow and measures reference materials which involve known values of thermal effusivity and heat capacity. In general, a complicated numerical iterative method and many thermophysical parameters are required for the calculation in the 3D heat flow model. Here, we devised a simple procedure by using a molybdenum (Mo) thin film with low thermal conductivity on the sample surface, enabling us to measure over a wide thermal effusivity range for various materials.

Thermal energy storage devices, systems, and thermal energy storage device monitoring methods

DOEpatents

Tugurlan, Maria; Tuffner, Francis K; Chassin, David P.

2016-09-13

Thermal energy storage devices, systems, and thermal energy storage device monitoring methods are described. According to one aspect, a thermal energy storage device includes a reservoir configured to hold a thermal energy storage medium, a temperature control system configured to adjust a temperature of the thermal energy storage medium, and a state observation system configured to provide information regarding an energy state of the thermal energy storage device at a plurality of different moments in time.

Thermally activated ("thermal") battery technology. Part IV. Anode materials

NASA Astrophysics Data System (ADS)

Guidotti, Ronald A.; Masset, Patrick J.

In this paper, the history of anode materials developed for use in thermally activated ("thermal") batteries is presented. The chemistries (phases) and electrochemical characteristics (discharge mechanisms) of these materials are described, along with general thermodynamic properties, where available. This paper is the last of a five-part series that presents a general review of thermal-battery technology.

Thermalization without eigenstate thermalization hypothesis after a quantum quench.

PubMed

Mori, Takashi; Shiraishi, Naoto

2017-08-01

Nonequilibrium dynamics of a nonintegrable system without the eigenstate thermalization hypothesis is studied. It is shown that, in the thermodynamic limit, this model thermalizes after an arbitrary quantum quench at finite temperature, although it does not satisfy the eigenstate thermalization hypothesis. In contrast, when the system size is finite and the temperature is low enough, the system may not thermalize. In this case, the steady state is well described by the generalized Gibbs ensemble constructed by using highly nonlocal conserved quantities. We also show that this model exhibits prethermalization, in which the prethermalized state is characterized by nonthermal energy eigenstates.

Thermally Conductive-Silicone Composites with Thermally Reversible Cross-links.

PubMed

Wertz, J T; Kuczynski, J P; Boday, D J

2016-06-08

Thermally conductive-silicone composites that contain thermally reversible cross-links were prepared by blending diene- and dienophile-functionalized polydimethylsiloxane (PDMS) with an aluminum oxide conductive filler. This class of thermally conductive-silicones are useful as thermal interface materials (TIMs) within Information Technology (IT) hardware applications to allow rework of valuable components. The composites were rendered reworkable via retro Diels-Alder cross-links when temperatures were elevated above 130 °C and required little mechanical force to remove, making them advantageous over other TIM materials. Results show high thermal conductivity (0.4 W/m·K) at low filler loadings (45 wt %) compared to other TIM solutions (>45 wt %). Additionally, the adhesion of the material was found to be ∼7 times greater at lower temperatures (25 °C) and ∼2 times greater at higher temperatures (120 °C) than commercially available TIMs.

SolSTUS: Solar Source Thermal Upper Stage

NASA Astrophysics Data System (ADS)

This paper was written by members of the Utah State University (USU) Space Systems Design class, fall quarter 1993. The class is funded by NASA and administered by the University Space Research Association (USRA). The focus of the class is to give students some experience in design of space systems and as a source of original ideas for NASA. This paper is a summary of the work done by members of the Space Systems Design class during the opening phase of the course. The class was divided into groups to work on different areas of the Solar Thermal Rocket (STR) booster in order to produce a design reference mission that would identify the key design issues. The design reference mission focused upon a small satellite mission to Mars. There are several critical components in a Solar Thermal Rocket. STR's produce a very low thrust, but have a high specific impulse, meaning that they take longer to reach the desired orbit, but use a lot less fuel in doing it. The complexity of the rocket is discussed in this paper. Some of the more critical design problems discussed are: (1) the structural and optical complexity of collecting and focusing sunlight onto a specific point, (2) long term storage of fuel (liquid hydrogen), (3) attitude control while thrusting in an elliptical orbit and orienting the mirrors to collect sunlight, and (4) power and communications for the rocket and it's internal systems. The design reference mission discussed here is a very general mission to Mars. A first order trajectory design has been done and a possible basic science payload for Mars has been suggested. This paper summarizes the design reference mission (DRM) formulated by the USU students during fall quarter and identifies major design challenges that will confront the design team during the next two quarters here at USU.

SolSTUS: Solar Source Thermal Upper Stage

NASA Technical Reports Server (NTRS)

1994-01-01

This paper was written by members of the Utah State University (USU) Space Systems Design class, fall quarter 1993. The class is funded by NASA and administered by the University Space Research Association (USRA). The focus of the class is to give students some experience in design of space systems and as a source of original ideas for NASA. This paper is a summary of the work done by members of the Space Systems Design class during the opening phase of the course. The class was divided into groups to work on different areas of the Solar Thermal Rocket (STR) booster in order to produce a design reference mission that would identify the key design issues. The design reference mission focused upon a small satellite mission to Mars. There are several critical components in a Solar Thermal Rocket. STR's produce a very low thrust, but have a high specific impulse, meaning that they take longer to reach the desired orbit, but use a lot less fuel in doing it. The complexity of the rocket is discussed in this paper. Some of the more critical design problems discussed are: (1) the structural and optical complexity of collecting and focusing sunlight onto a specific point, (2) long term storage of fuel (liquid hydrogen), (3) attitude control while thrusting in an elliptical orbit and orienting the mirrors to collect sunlight, and (4) power and communications for the rocket and it's internal systems. The design reference mission discussed here is a very general mission to Mars. A first order trajectory design has been done and a possible basic science payload for Mars has been suggested. This paper summarizes the design reference mission (DRM) formulated by the USU students during fall quarter and identifies major design challenges that will confront the design team during the next two quarters here at USU.

Thermal Conductivity and Sintering Behavior of Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2002-01-01

Advanced thermal barrier coatings, having significantly reduced long-term thermal conductivities, are being developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and physical vapor-deposited thermal barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

Solar Simulation for the CREST Preflight Thermal-Vacuum Test at B-2

NASA Technical Reports Server (NTRS)

Ziemke, Robert A.

2012-01-01

In June 2011, the multi-university sponsored Cosmic Ray Electron Synchrotron Telescope (CREST) has undergone thermal-vacuum qualification testing at the NASA Glenn Research Center (GRC), Plum Brook Station, Sandusky, Ohio. The testing was performed in the B-2 Space Propulsion Facility vacuum chamber. The CREST was later flown over the Antarctic region as the payload of a stratospheric balloon. Solar simulation was provided by a system of planar infrared lamp arrays specifically designed for CREST. The lamp arrays, in conjunction with a liquid-nitrogen-cooled cold wall, achieved the required thermal conditions for the qualification tests. The following slides accompanied the presentation of the report entitled Solar Simulation for the CREST Preflight Thermal-Vacuum Test at B-2, at the 27th Aerospace Testing Seminar, October 2012. The presentation described the test article, the test facility capability, the solar simulation requirements, the highlights of the engineering approach, and the results achieved. The presentation was intended to generate interest in the report and in the B-2 test facility.

Russ Donnelly's research at the University of Oregon

NASA Astrophysics Data System (ADS)

Niemela, Joseph

2015-11-01

Coming to the University of Oregon in 1966, Russ Donnelly built up a strong research activity having two threads within hydrodynamics: the flow of ordinary fluids and that of superfluids. Vortices-quantized and classical-were at the heart of his research. His 1991 book ``Quantized Vortices in Helium II,'' by now a standard reference for researchers and students, elucidated some of it. To produce vortices Russ brought from Chicago two enormous rotating tables, based on 1-m diameter industrial lathe chucks obtained from General Motors. They were also used for classical systems such as Taylor-Couette flow (to generate strong Coriolis forces) and thermal convection, where the properties of rotation-including early experimental investigations of the Kuppers-Lortz instability-were studied. Another common thread in his research was the modulation of control parameters leading to Stokes layer effects, both thermal and viscous. In the early `90s, Russ and his group turned their attention to cryogenic turbulence in normal and superfluid systems, creating what has now become a small industry and a well-established sub-field within low temperature physics.

Updates to SCORPION persistent surveillance system with universal gateway

NASA Astrophysics Data System (ADS)

Coster, Michael; Chambers, Jon; Winters, Michael; Brunck, Al

2008-10-01

This paper addresses benefits derived from the universal gateway utilized in Northrop Grumman Systems Corporation's (NGSC) SCORPION, a persistent surveillance and target recognition system produced by the Xetron campus in Cincinnati, Ohio. SCORPION is currently deployed in Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF). The SCORPION universal gateway is a flexible, field programmable system that provides integration of over forty Unattended Ground Sensor (UGS) types from a variety of manufacturers, multiple visible and thermal electro-optical (EO) imagers, and numerous long haul satellite and terrestrial communications links, including the Army Research Lab (ARL) Blue Radio. Xetron has been integrating best in class sensors with this universal gateway to provide encrypted data exfiltration to Common Operational Picture (COP) systems and remote sensor command and control since 1998. In addition to being fed to COP systems, SCORPION data can be visualized in the Common sensor Status (CStat) graphical user interface that allows for viewing and analysis of images and sensor data from up to seven hundred SCORPION system gateways on single or multiple displays. This user friendly visualization enables a large amount of sensor data and imagery to be used as actionable intelligence by a minimum number of analysts.

Noninvasive imaging analysis of biological tissue associated with laser thermal injury.

PubMed

Chang, Cheng-Jen; Yu, De-Yi; Hsiao, Yen-Chang; Ho, Kuang-Hua

2017-04-01

The purpose of our study is to use a noninvasive tomographic imaging technique with high spatial resolution to characterize and monitor biological tissue responses associated with laser thermal injury. Optical doppler tomography (ODT) combines laser doppler flowmetry (LDF) with optical coherence tomography (OCT) to obtain high resolution tomographic velocity and structural images of static and moving constituents in highly scattering biological tissues. A SurgiLase XJ150 carbon dioxide (CO 2 ) laser using a continuous mode of 3 watts (W) was used to create first, second or third degree burns on anesthetized Sprague-Dawley rats. Additional parameters for laser thermal injury were assessed as well. The rationale for using ODT in the evaluation of laser thermal injury offers a means of constructing a high resolution tomographic image of the structure and perfusion of laser damaged skin. In the velocity images, the blood flow is coded at 1300 μm/s and 0 velocity, 1000 μm/s and 0 velocity, 700 μm/s and 0 velocity adjacent to the first, second, and third degree injuries, respectively. ODT produces exceptional spatial resolution while having a non-invasive way of measurement, therefore, ODT is an accurate measuring method for high-resolution fluid flow velocity and structural images for biological tissue with laser thermal injury. Copyright © 2017 Chang Gung University. Published by Elsevier B.V. All rights reserved.

Universality in volume-law entanglement of scrambled pure quantum states.

PubMed

Nakagawa, Yuya O; Watanabe, Masataka; Fujita, Hiroyuki; Sugiura, Sho

2018-04-24

A pure quantum state can fully describe thermal equilibrium as long as one focuses on local observables. The thermodynamic entropy can also be recovered as the entanglement entropy of small subsystems. When the size of the subsystem increases, however, quantum correlations break the correspondence and mandate a correction to this simple volume law. The elucidation of the size dependence of the entanglement entropy is thus essentially important in linking quantum physics with thermodynamics. Here we derive an analytic formula of the entanglement entropy for a class of pure states called cTPQ states representing equilibrium. We numerically find that our formula applies universally to any sufficiently scrambled pure state representing thermal equilibrium, i.e., energy eigenstates of non-integrable models and states after quantum quenches. Our formula is exploited as diagnostics for chaotic systems; it can distinguish integrable models from non-integrable models and many-body localization phases from chaotic phases.

PREFACE: Eurotherm Conference No. 95: Computational Thermal Radiation in Participating Media IV

NASA Astrophysics Data System (ADS)

Boulet, Pascal; Lacroix, David; Lemonnier, Denis; Lybaert, Paul; Selçuk, Nevin

2012-06-01

This volume of Journal of Physics: Conference Series is based on papers presented at the Eurotherm Conference 95: Computational Thermal Radiation in Participating Media IV, which was held in Nancy, France, on 18-20 April 2012. This seminar was the fourth in a series after Mons, Belgium (Eurotherm Seminar 73, April 2003), Poitiers, France (Eurotherm Seminar 78, April 2006) and Lisbon, Portugal (Eurotherm Seminar 83, April 2009). Around 70 contributions were received during the conference preparation, including submissions for oral and poster presentations. A first selection process based on abstracts and a second based on two peer-reviews of the full papers finally resulted in the acceptance of 38 contributions from oral presentations and 11 from poster presentations. The conference was attended by almost 80 scientists from 17 different countries: Austria, Belgium, Brazil, Canada, Chile, China, France, Germany, India, Poland, Portugal, Russia, Switzerland, The Netherlands, Tunisia, Turkey and USA. The 30 contributions presented in this volume relate to the following main topics: Radiative transfer in complex media Applications, combustion and high temperatures Inverse methods New developments for RTE solution Gas radiation modeling Particles, droplets and dispersed systems Monte Carlo methods The conference organizers gratefully acknowledge the members of the scientific committee and the experts who carried out the reviews of the papers, and the local organizing committee for their preparation of the conference. Also acknowledged are the support by the LEMTA, the Société Française de Thermique, ICHMT, the sponsorship of CNRS and the Lorraine Region, and the financial contributions of the Université de Lorraine, FLIR, Baccarat and the city of Nancy. Conference Chairs P BouletLEMTA, Nancy, France D LemonnierInstitut P', Poitiers, France N SelçukMiddle East Technical University, Ankara, Turkey P LybaertFaculté Polytechnique de Mons, Belgium International

Thermal feature extraction of servers in a datacenter using thermal image registration

NASA Astrophysics Data System (ADS)

Liu, Hang; Ran, Jian; Xie, Ting; Gao, Shan

2017-09-01

Thermal cameras provide fine-grained thermal information that enhances monitoring and enables automatic thermal management in large datacenters. Recent approaches employing mobile robots or thermal camera networks can already identify the physical locations of hot spots. Other distribution information used to optimize datacenter management can also be obtained automatically using pattern recognition technology. However, most of the features extracted from thermal images, such as shape and gradient, may be affected by changes in the position and direction of the thermal camera. This paper presents a method for extracting the thermal features of a hot spot or a server in a container datacenter. First, thermal and visual images are registered based on textural characteristics extracted from images acquired in datacenters. Then, the thermal distribution of each server is standardized. The features of a hot spot or server extracted from the standard distribution can reduce the impact of camera position and direction. The results of experiments show that image registration is efficient for aligning the corresponding visual and thermal images in the datacenter, and the standardization procedure reduces the impacts of camera position and direction on hot spot or server features.

Electrical and thermal conductance quantization in nanostructures

NASA Astrophysics Data System (ADS)

Nawrocki, Waldemar

2008-10-01

In the paper problems of electron transport in mesoscopic structures and nanostructures are considered. The electrical conductance of nanowires was measured in a simple experimental system. Investigations have been performed in air at room temperature measuring the conductance between two vibrating metal wires with standard oscilloscope. Conductance quantization in units of G0 = 2e2/h = (12.9 kΩ)-1 up to five quanta of conductance has been observed for nanowires formed in many metals. The explanation of this universal phenomena is the formation of a nanometer-sized wire (nanowire) between macroscopic metallic contacts which induced, due to theory proposed by Landauer, the quantization of conductance. Thermal problems in nanowires are also discussed in the paper.

Thermal performance and heat transport in aquifer thermal energy storage

NASA Astrophysics Data System (ADS)

Sommer, W. T.; Doornenbal, P. J.; Drijver, B. C.; van Gaans, P. F. M.; Leusbrock, I.; Grotenhuis, J. T. C.; Rijnaarts, H. H. M.

2014-01-01

Aquifer thermal energy storage (ATES) is used for seasonal storage of large quantities of thermal energy. Due to the increasing demand for sustainable energy, the number of ATES systems has increased rapidly, which has raised questions on the effect of ATES systems on their surroundings as well as their thermal performance. Furthermore, the increasing density of systems generates concern regarding thermal interference between the wells of one system and between neighboring systems. An assessment is made of (1) the thermal storage performance, and (2) the heat transport around the wells of an existing ATES system in the Netherlands. Reconstruction of flow rates and injection and extraction temperatures from hourly logs of operational data from 2005 to 2012 show that the average thermal recovery is 82 % for cold storage and 68 % for heat storage. Subsurface heat transport is monitored using distributed temperature sensing. Although the measurements reveal unequal distribution of flow rate over different parts of the well screen and preferential flow due to aquifer heterogeneity, sufficient well spacing has avoided thermal interference. However, oversizing of well spacing may limit the number of systems that can be realized in an area and lower the potential of ATES.

A photon thermal diode

PubMed Central

Chen, Zhen; Wong, Carlaton; Lubner, Sean; Yee, Shannon; Miller, John; Jang, Wanyoung; Hardin, Corey; Fong, Anthony; Garay, Javier E.; Dames, Chris

2014-01-01

A thermal diode is a two-terminal nonlinear device that rectifies energy carriers (for example, photons, phonons and electrons) in the thermal domain, the heat transfer analogue to the familiar electrical diode. Effective thermal rectifiers could have an impact on diverse applications ranging from heat engines to refrigeration, thermal regulation of buildings and thermal logic. However, experimental demonstrations have lagged far behind theoretical proposals. Here we present the first experimental results for a photon thermal diode. The device is based on asymmetric scattering of ballistic energy carriers by pyramidal reflectors. Recent theoretical work has predicted that this ballistic mechanism also requires a nonlinearity in order to yield asymmetric thermal transport, a requirement of all thermal diodes arising from the second Law of Thermodynamics, and realized here using an ‘inelastic thermal collimator’ element. Experiments confirm both effects: with pyramids and collimator the thermal rectification is 10.9±0.8%, while without the collimator no rectification is detectable (<0.3%). PMID:25399761

Dosimetric and microdosimetric analyses for blood exposed to reactor-derived thermal neutrons.

PubMed

Ali, F; Atanackovic, J; Boyer, C; Festarini, A; Kildea, J; Paterson, L C; Rogge, R; Stuart, M; Richardson, R B

2018-06-06

Thermal neutrons are found in reactor, radiotherapy, aircraft, and space environments. The purpose of this study was to characterise the dosimetry and microdosimetry of thermal neutron exposures, using three simulation codes, as a precursor to quantitative radiobiological studies using blood samples. An irradiation line was designed employing a pyrolytic graphite crystal or-alternatively-a super mirror to expose blood samples to thermal neutrons from the National Research Universal reactor to determine radiobiological parameters. The crystal was used when assessing the relative biological effectiveness for dicentric chromosome aberrations, and other biomarkers, in lymphocytes over a low absorbed dose range of 1.2-14 mGy. Higher exposures using a super mirror will allow the additional quantification of mitochondrial responses. The physical size of the thermal neutron fields and their respective wavelength distribution was determined using the McStas Monte Carlo code. Spinning the blood samples produced a spatially uniform absorbed dose as determined from Monte Carlo N-Particle version 6 simulations. The major part (71%) of the total absorbed dose to blood was determined to be from the 14 N(n,p) 14 C reaction and the remainder from the 1 H(n,γ) 2 H reaction. Previous radiobiological experiments at Canadian Nuclear Laboratories involving thermal neutron irradiation of blood yielded a relative biological effectiveness of 26 ± 7. Using the Particle and Heavy Ion Transport Code System, a similar value of ∼19 for the quality factor of thermal neutrons initiating the 14 N(n,p) 14 C reaction in soft tissue was determined by microdosimetric simulations. This calculated quality factor is of similar high value to the experimentally-derived relative biological effectiveness, and indicates the potential of thermal neutrons to induce deleterious health effects in superficial organs such as cataracts of the eye lens.

Thermal to electricity conversion using thermal magnetic properties

DOEpatents

West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

2010-04-27

A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

EVALUATION OF TWO METHODS OF THERMAL WEED CONTROL IN FRUIT TREE ORCHARDS, PESTICIDE SPECIAL STUDY, COLORADO STATE UNIVERSITY

EPA Science Inventory

Research Objectives: 1) Compare the efficiency of two different types of thermal flamers: a direct flamer (Red Dragon, Inc., LaCrosse, Kansas) and a prototype infrared weed flamer (Sunburst, Inc., Eugene Oregon) in controlling weed populations in an apple orchard. 2) Determine ...

Ion trap simulations of quantum fields in an expanding universe.

PubMed

Alsing, Paul M; Dowling, Jonathan P; Milburn, G J

2005-06-10

We propose an experiment in which the phonon excitation of ion(s) in a trap, with a trap frequency exponentially modulated at rate kappa, exhibits a thermal spectrum with an "Unruh" temperature given by k(B)T=Planck kappa. We discuss the similarities of this experiment to the response of detectors in a de Sitter universe and the usual Unruh effect for uniformly accelerated detectors. We demonstrate a new Unruh effect for detectors that respond to antinormally ordered moments using the ion's first blue sideband transition.

Thermal transport in boron nitride nanotorus—towards a nanoscopic thermal shield

NASA Astrophysics Data System (ADS)

Loh, G. C.; Baillargeat, D.

2013-11-01

Nanotori, or nanorings, are topological variants of nanotubes and are conceived to have different properties from their tubular form. In this study, the toroidal arrangement of boron nitride is introduced. Using classical molecular dynamics simulations, the thermal behaviour (thermal conductivity and thermal stability) of the boron nitride nanotorus and its relationship with the structural characteristics are investigated. Its circumferential thermal rectification strength displays a linear dependence on the bending coefficient of the nanostructure. Surface kinks are relatively inconsequential on its circumferential mode of conduction, as compared to its axial sense. The circumferential conductivity in the diffusive regime is calculated to be approximately 10 W/m K, while the axial conductivity is more than tenfold of this value. All nanotori with different toroidal characters show excellent thermal stability at extremely high temperatures approaching 3400 K. With consideration to its favourable properties, a thermal shield made up of a parallel row of nanotori is proposed as a nanoscale thermal insulation device.

PeV-scale dark matter as a thermal relic of a decoupled sector

DOE PAGES

Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

2016-06-21

We consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter, metastable state, whose subsequent abundance can naturally come to dominate the energy density of the universe. Moreover, when this state decays, it reheats the visible sector and dilutes all relic abundances, thereby allowing the dark matter to be orders of magnitude heavier than the weak scale. For concreteness, we consider a simple realization with a Dirac fermion dark matter candidate coupledmore » to a massive gauge boson that decays to the Standard Model through its kinetic mixing with hypercharge. Finally, we identify viable parameter space in which the dark matter can be as heavy as ~1-100 PeV without being overproduced in the early universe.« less

Thermal analysis of Malaysian double storey housing - low/medium cost unit

NASA Astrophysics Data System (ADS)

Normah, M. G.; Lau, K. Y.; Yusoff, S. Mohd.

2012-06-01

Almost half of the total energy used today is consumed in buildings. In the tropical climate, air-conditioning a housing unit takes much of the energy bill. Malaysia is no exception. Malaysian double storey terrace housing is popular among developers and buyers. Surveys have shown that housing occupants are much dissatisfied with the thermal comfort and artificial cooling is often sought. The objective of this study is to assess the thermal comfort of the low and medium-cost double storey housing in the area surrounding Universiti Teknologi Malaysia. A simulation program using the Weighting Factor Method calculates the heat transfer interaction, temperature distribution, and PMV level in three types of housing units in relation to the size. Fanger's PMV model based on ISO Standard 7730 is used here because it accounts for all parameters that affect the thermal sensation of a human within its equation. Results showed that both the low and medium-cost housing units studied are out of the comfortable range described by ASHRAE Standard 55 with the units all complied with the local bylaws. In view of the uncertainties in energy supply, future housing units should consider natural ventilation as part of the passive energy management.

Measurement of thermal conductivity and thermal diffusivity using a thermoelectric module

NASA Astrophysics Data System (ADS)

Beltrán-Pitarch, Braulio; Márquez-García, Lourdes; Min, Gao; García-Cañadas, Jorge

2017-04-01

A proof of concept of using a thermoelectric module to measure both thermal conductivity and thermal diffusivity of bulk disc samples at room temperature is demonstrated. The method involves the calculation of the integral area from an impedance spectrum, which empirically correlates with the thermal properties of the sample through an exponential relationship. This relationship was obtained employing different reference materials. The impedance spectroscopy measurements are performed in a very simple setup, comprising a thermoelectric module, which is soldered at its bottom side to a Cu block (heat sink) and thermally connected with the sample at its top side employing thermal grease. Random and systematic errors of the method were calculated for the thermal conductivity (18.6% and 10.9%, respectively) and thermal diffusivity (14.2% and 14.7%, respectively) employing a BCR724 standard reference material. Although errors are somewhat high, the technique could be useful for screening purposes or high-throughput measurements at its current state. This new method establishes a new application for thermoelectric modules as thermal properties sensors. It involves the use of a very simple setup in conjunction with a frequency response analyzer, which provides a low cost alternative to most of currently available apparatus in the market. In addition, impedance analyzers are reliable and widely spread equipment, which facilities the sometimes difficult access to thermal conductivity facilities.

A quantitative sensitivity analysis on the behaviour of common thermal indices under hot and windy conditions in Doha, Qatar

NASA Astrophysics Data System (ADS)

Fröhlich, Dominik; Matzarakis, Andreas

2016-04-01

Human thermal perception is best described through thermal indices. The most popular thermal indices applied in human bioclimatology are the perceived temperature (PT), the Universal Thermal Climate Index (UTCI), and the physiologically equivalent temperature (PET). They are analysed focusing on their sensitivity to single meteorological input parameters under the hot and windy meteorological conditions observed in Doha, Qatar. It can be noted, that the results for the three indices are distributed quite differently. Furthermore, they respond quite differently to modifications in the input conditions. All of them show particular limitations and shortcomings that have to be considered and discussed. While the results for PT are unevenly distributed, UTCI shows limitations concerning the input data accepted. PET seems to respond insufficiently to changes in vapour pressure. The indices should therefore be improved to be valid for several kinds of climates.

Atmospheric effects on the mapping of Martian thermal inertia and thermally derived albedo

NASA Technical Reports Server (NTRS)

Hayashi, Joan N.; Jakosky, Bruce M.; Haberle, Robert M.

1995-01-01

We examine the effects of a dusty C02 atmosphere on the thermal inertia and thermally derived albedo of Mars and we present a new map of thermal inertias. This new map was produced using a coupled surface atmosphere (CSA) model, dust opacities from Viking infrared thermal mapper (IRTM) data, and C02 columns based on topography. The CSA model thermal inertias are smaller than the 2% model thermal inertias, with the difference largest at large thermal inertia. Although the difference between the thermal inertias obtained with the two models is moderate for much of the region studied, it is largest in regions of either high dust opacity or of topographic lows, including the Viking Lander 1 site and some geologically interesting regions. The CSA model thermally derived albedos do not accurately predict the IRTM measured albedos and are very similar to the thermally derived albedos obtained with models making the 2% assumption.

Atmospheric effects on the mapping of Martian thermal inertia and thermally derived albedo

NASA Technical Reports Server (NTRS)

Hayashi, Joan N.; Jakosky, Bruce M.; Haberle, Robert M.

1995-01-01

We examine the effects of a dusty CO2 atmosphere on the thermal inertia and thermally derived albedo of Mars and we present a new map of thermal inertias. This new map was produced using a coupled surface atmosphere (CSA) model, dust opacities from Viking infrared thermal mapper (IRTM) data, and CO2 columns based on topography. The CSA model thermal inertias are smaller than the 2% model thermal inertias, with the difference largest at large thermal inertia. Although the difference between the thermal inertias obtained with the two models is moderate for much of the region studied, it is largest in regions of either high dust opacity or of topographic lows, including the Viking Lander 1 site and some geologically interesting regions. The CSA model thermally derived albedos do not acurately predict the IRTM measured albedos and are very similar to the thermally derived albedos obtained with models making the 2% assumption.

Width of thermal damage after using the YAG contact laser for cutting biological tissue: animal experimental investigation.

PubMed

Mecke, H; Schünke, M; Schnaidt, S; Freys, I; Semm, K

1991-01-01

At the University Women's Clinic in Kiel, the YAG contact laser has been used as a cutting instrument in pelviscopic operations since 1987. When the laser cuts, it produces only a scant amount of mechanical trauma. The determining factor is the amount of thermal damage produced along the wound margins and in direct neighboring tissue. The extent of the tissue change seen in the uterus and liver parenchyma of rats and the striated muscle of rabbits after application of the YAG contact laser was demonstrated using various staining techniques and stains. Liver parenchyma proved to be the most sensitive to thermal damage. In the uterine horn, enzyme-histochemical ATPase and alkaline phosphatase demonstrations showed a significantly wider zone of thermal damage after laser incision than did hematoxylin-eosin and Goldner staining techniques. A good understanding of the extent of thermal damage is essential for atraumatic pelviscopic operations using the YAG contact laser and also for the preventing of complications.

Latitude variation of the subsurface lunar temperature: Lunar Prospector thermal neutrons

NASA Astrophysics Data System (ADS)

Little, R. C.; Feldman, W. C.; Maurice, S.; Genetay, I.; Lawrence, D. J.; Lawson, S. L.; Gasnault, O.; Barraclough, B. L.; Elphic, R. C.; Prettyman, T. H.; Binder, A. B.

2003-05-01

Planetary thermal neutron fluxes provide a sensitive proxy for mafic and feldspathic terranes and are also necessary for translating measured gamma-ray line strengths to elemental abundances. Both functions require a model for near-surface temperatures and a knowledge of the dependence of thermal neutron flux on temperature. We have explored this dependence for a representative sample of lunar soil compositions and surface temperatures using the Monte Carlo N-Particle Code (MCNP™)(MNCP is a trademark of the Regents of the University of California, Los Alamos National Laboratory). For all soil samples, the neutron density is found to be independent of temperature, in accord with neutron moderation theory. The thermal neutron flux, however, does vary with temperature in a way that depends on Δ, the ratio of macroscopic absorption to energy-loss cross sections of soil compositions. The weakest dependence is for the largest Δ (which corresponds to the Apollo 17 high-Ti basalt in our soil selection), and the largest dependence is for the lowest Δ (which corresponds to ferroan anorthosite, [FAN] in our selection). For the lunar model simulated, the depth at which the thermal neutron population is most sensitive to temperature is ~30 g cm-2. These simulations were compared with the flux of thermal neutrons measured using the Lunar Prospector neutron spectrometer over the lunar highlands using a subsurface temperature profile that varies with latitude, λ, as Cos1/4λ. Model results assuming equatorial temperatures of 200 and 250 K are in reasonable agreement with measured data. This range of equatorial temperatures is not inconsistent with the average temperature measured below the diurnal thermal wave at the equator, Tmeas = 252 +/- 3 K [Langseth and Keihm, 1977].

Advanced Thermal Simulator Testing: Thermal Analysis and Test Results

NASA Technical Reports Server (NTRS)

Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David; Reid, Robert; Adams, Mike; Davis, Joe

2008-01-01

Work at the NASA Marshall Space Flight Center seeks to develop high fidelity, electrically heated thermal simulators that represent fuel elements in a nuclear reactor design to support non-nuclear testing applicable to the development of a space nuclear power or propulsion system. Comparison between the fuel pins and thermal simulators is made at the outer fuel clad surface, which corresponds to the outer sheath surface in the thermal simulator. The thermal simulators that are currently being tested correspond to a SNAP derivative reactor design that could be applied for Lunar surface power. These simulators are designed to meet the geometric and power requirements of a proposed surface power reactor design, accommodate testing of various axial power profiles, and incorporate imbedded instrumentation. This paper reports the results of thermal simulator analysis and testing in a bare element configuration, which does not incorporate active heat removal, and testing in a water-cooled calorimeter designed to mimic the heat removal that would be experienced in a reactor core.

Periodic composites: quasi-uniform heat conduction, Janus thermal illusion, and illusion thermal diodes

NASA Astrophysics Data System (ADS)

Xu, Liujun; Jiang, Chaoran; Shang, Jin; Wang, Ruizhe; Huang, Jiping

2017-11-01

Manipulating thermal conductivities at will plays a crucial role in controlling heat flow. By developing an effective medium theory including periodicity, here we experimentally show that nonuniform media can exhibit quasi-uniform heat conduction. This provides capabilities in proposing Janus thermal illusion and illusion thermal rectification. For the former, we study, via experiment and theory, a big periodic composite containing a small periodic composite with circular or elliptic particles. As a result, we reveal the Janus thermal illusion that describes the whole periodic system with both invisibility illusion along one direction and visibility illusion along the perpendicular direction, which is fundamentally different from the existing thermal illusions for misleading thermal detection. Further, the Janus illusion helps to design two different periodic systems that both work as thermal diodes but with nearly the same temperature distribution, heat fluxes and rectification ratios, thus being called illusion thermal diodes. Such thermal diodes differ from those extensively studied in the literature, and are useful for the areas that require both thermal rectification and thermal camouflage. This work not only opens a door for designing novel periodic composites in thermal camouflage and heat rectification, but also holds for achieving similar composites in other disciplines like electrostatics, magnetostatics, and particle dynamics.

A Thermal Management System Using Ammonium Carbamate as an Endothermic Heat Sink (POSTPRINT)

DTIC Science & Technology

2017-04-01

Niedbalski and Soumya S. Patnaik Mechanical and Thermal Systems Branch Power and Control Division Douglas J. Johnson and Jamie S. Ervin University...failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE...and Control Division Air Force Research Laboratory, Aerospace Systems Directorate Wright-Patterson Air Force Base, OH 45433-7542 Air Force Materiel

Universal Pinning Energy Barrier for Driven Domain Walls in Thin Ferromagnetic Films

NASA Astrophysics Data System (ADS)

Jeudy, V.; Mougin, A.; Bustingorry, S.; Savero Torres, W.; Gorchon, J.; Kolton, A. B.; Lemaître, A.; Jamet, J.-P.

2016-07-01

We report a comparative study of magnetic field driven domain wall motion in thin films made of different magnetic materials for a wide range of field and temperature. The full thermally activated creep motion, observed below the depinning threshold, is shown to be described by a unique universal energy barrier function. Our findings should be relevant for other systems whose dynamics can be modeled by elastic interfaces moving on disordered energy landscapes.

PREFACE: 1st International Symposium on Electrical Arc and Thermal Plasmas in Africa (ISAPA)

NASA Astrophysics Data System (ADS)

Andre, Pascal; Koalaga, Zacharie

2012-02-01

Logos of the University of Ouagadougou, ISAPA and Universite Blaise Pascal Africa (especially Sub-Saharan Africa) is a continent where electrification is at a low level. However, the development of the electrical power sector is a prerequisite for the growth of other industrial activities, that is to say for the social and economic development of African countries. Consequently, a large number of electrification projects (rural electrification, interconnection of different country's grids) takes place in many countries. These projects need expertise and make Africa a continent of opportunity for companies in different domains for business and research: energy; energetic production, transmission, distribution and protection of electricity; the supply of cable; the construction, engineering and expertise in the field of solar and wind power. The first International Symposium on electrical Arc and thermal Plasma in Africa (ISAPA) was held for the first time in Ouagadougou, Burkina Faso to progress and develop the research of new physical developments, technical breakthroughs, and ideas in the fields of electrical production and electrical applications. The ISAPA aims to encourage the advancement of the science and applications of electrical power transformation in Africa by bringing together specialists from many areas in Africa and the rest of the world. Such considerations have led us to define a Scientific Committee including representatives from many countries. This first meeting was an innovative opportunity for researchers and engineers from academic and industrial sectors to exchange views and knowledge. Both fundamental aspects such as thermal plasma, electrical arc, diagnostics and applied aspects as circuit breakers, ICP analyses, photovoltaic energy conversion and alternative energies, as well as space applications were covered. The Laboratory of Material and Environment (LAME) from Ouagadougou University and the Laboratory of Electric Arc and Thermal

Does oxygen limit thermal tolerance in arthropods? A critical review of current evidence.

PubMed

Verberk, Wilco C E P; Overgaard, Johannes; Ern, Rasmus; Bayley, Mark; Wang, Tobias; Boardman, Leigh; Terblanche, John S

2016-02-01

Over the last decade, numerous studies have investigated the role of oxygen in setting thermal tolerance in aquatic animals, and there has been particular focus on arthropods. Arthropods comprise one of the most species-rich taxonomic groups on Earth, and display great diversity in the modes of ventilation, circulation, blood oxygen transport, with representatives living both in water (mainly crustaceans) and on land (mainly insects). The oxygen and capacity limitation of thermal tolerance (OCLTT) hypothesis proposes that the temperature dependent performance curve of animals is shaped by the capacity for oxygen delivery in relation to oxygen demand. If correct, oxygen limitation could provide a mechanistic framework to understand and predict both current and future impacts of rapidly changing climate. In arthropods, most studies testing the OCLTT hypothesis have considered tolerance to thermal extremes. These studies likely operate from the philosophical viewpoint that if the model can predict these critical thermal limits, then it is more likely to also explain loss of performance at less extreme, non-lethal temperatures, for which much less data is available. Nevertheless, the extent to which lethal temperatures are influenced by limitations in oxygen supply remains unresolved. Here we critically evaluate the support and universal applicability for oxygen limitation being involved in lethal temperatures in crustaceans and insects. The relatively few studies investigating the OCLTT hypothesis at low temperature do not support a universal role for oxygen in setting the lower thermal limits in arthropods. With respect to upper thermal limits, the evidence supporting OCLTT is stronger for species relying on underwater gas exchange, while the support for OCLTT in air-breathers is weak. Overall, strongest support was found for increased anaerobic metabolism close to thermal maxima. In contrast, there was only mixed support for the prediction that aerobic scope

Thermal development of latent fingermarks on porous surfaces--further observations and refinements.

PubMed

Song, Di Fei; Sommerville, Daniel; Brown, Adam G; Shimmon, Ronald G; Reedy, Brian J; Tahtouh, Mark

2011-01-30

treated thermally after having been developed with ninhydrin or DFO. Aged fingermarks, including marks from 1-year-old university examination papers were successfully developed using the thermal technique. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Multiple thermal transitions and anisotropic thermal expansions of vertically aligned carbon nanotubes

NASA Astrophysics Data System (ADS)

Ya'akobovitz, Assaf

2016-10-01

Vertically aligned carbon nanotubes (VA-CNTs) hold the potential to play an instrumental role in a wide variety of applications in micro- and nano-devices and composites. However, their successful large-scale implementation in engineering systems requires a thorough understanding of their material properties, including their thermal behavior, which was the focus of the current study. Thus, the thermal expansion of as-grown VA-CNT microstructures was investigated while increasing the temperature from room temperature to 800 °C and then cooling it down. First thermal transition was observed at 191 ± 68 °C during heating, and an additional thermal transition was observed at 523 ± 138 °C during heating and at similar temperatures during cooling. Each thermal transition was characterized by a significant change in the coefficient of thermal expansion (CTE), which can be related to a morphological change in the VA-CNT microstructures. Measurements of the CTEs in the lateral directions revealed differences in the lateral thermal behaviors of the top, middle, and bottom portions of the VA-CNT microstructures, again indicating that their morphology dominates their thermal characteristics. A hysteretic behavior was observed, as the measured values of CTEs were altered due to the applied thermal loads and the height of the microstructures was slightly higher compared to its initial value. These findings provide an insight into the anisotropic thermal behavior of VA-CNT microstructures and shed light on the relationship between their morphology and thermal behavior.

Analysis of the variation of range parameters of thermal cameras

NASA Astrophysics Data System (ADS)

Bareła, Jarosław; Kastek, Mariusz; Firmanty, Krzysztof; Krupiński, Michał

2016-10-01

Measured range characteristics may vary considerably (up to several dozen percent) between different samples of the same camera type. The question is whether the manufacturing process somehow lacks repeatability or the commonly used measurement procedures themselves need improvement. The presented paper attempts to deal with the aforementioned question. The measurement method has been thoroughly analyzed as well as the measurement test bed. Camera components (such as detector and optics) have also been analyzed and their key parameters have been measured, including noise figures of the entire system. Laboratory measurements are the most precise method used to determine range parameters of a thermal camera. However, in order to obtain reliable results several important conditions have to be fulfilled. One must have the test equipment capable of measurement accuracy (uncertainty) significantly better than the magnitudes of measured quantities. The measurements must be performed in a controlled environment thus excluding the influence of varying environmental conditions. The personnel must be well-trained, experienced in testing the thermal imaging devices and familiar with the applied measurement procedures. The measurement data recorded for several dozen of cooled thermal cameras (from one of leading camera manufacturers) have been the basis of the presented analysis. The measurements were conducted in the accredited research laboratory of Institute of Optoelectronics (Military University of Technology).

Thermal-Wave Imaging.

ERIC Educational Resources Information Center

Rosencwaig, Allan

1982-01-01

Thermal features of and beneath the surface of a sample can be detected and imaged with a thermal-wave microscope. Various methodologies for the excitation and detection of thermal waves are discussed, and several applications, primarily in microelectronics, are presented. (Author)

Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

USGS Publications Warehouse

Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

2006-01-01

Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

Metallic superhydrophobic surfaces via thermal sensitization

NASA Astrophysics Data System (ADS)

Vahabi, Hamed; Wang, Wei; Popat, Ketul C.; Kwon, Gibum; Holland, Troy B.; Kota, Arun K.

2017-06-01

Superhydrophobic surfaces (i.e., surfaces extremely repellent to water) allow water droplets to bead up and easily roll off from the surface. While a few methods have been developed to fabricate metallic superhydrophobic surfaces, these methods typically involve expensive equipment, environmental hazards, or multi-step processes. In this work, we developed a universal, scalable, solvent-free, one-step methodology based on thermal sensitization to create appropriate surface texture and fabricate metallic superhydrophobic surfaces. To demonstrate the feasibility of our methodology and elucidate the underlying mechanism, we fabricated superhydrophobic surfaces using ferritic (430) and austenitic (316) stainless steels (representative alloys) with roll off angles as low as 4° and 7°, respectively. We envision that our approach will enable the fabrication of superhydrophobic metal alloys for a wide range of civilian and military applications.

Josephson Thermal Memory

NASA Astrophysics Data System (ADS)

Guarcello, Claudio; Solinas, Paolo; Braggio, Alessandro; Di Ventra, Massimiliano; Giazotto, Francesco

2018-01-01

We propose a superconducting thermal memory device that exploits the thermal hysteresis in a flux-controlled temperature-biased superconducting quantum-interference device (SQUID). This system reveals a flux-controllable temperature bistability, which can be used to define two well-distinguishable thermal logic states. We discuss a suitable writing-reading procedure for these memory states. The time of the memory writing operation is expected to be on the order of approximately 0.2 ns for a Nb-based SQUID in thermal contact with a phonon bath at 4.2 K. We suggest a noninvasive readout scheme for the memory states based on the measurement of the effective resonance frequency of a tank circuit inductively coupled to the SQUID. The proposed device paves the way for a practical implementation of thermal logic and computation. The advantage of this proposal is that it represents also an example of harvesting thermal energy in superconducting circuits.

Thermal conductivity and thermal expansion of graphite fiber/copper matrix composites

NASA Technical Reports Server (NTRS)

Ellis, David L.; Mcdanels, David L.

1991-01-01

The high specific conductivity of graphite fiber/copper matrix (Gr/Cu) composites offers great potential for high heat flux structures operating at elevated temperatures. To determine the feasibility of applying Gr/Cu composites to high heat flux structures, composite plates were fabricated using unidirectional and cross-plied pitch-based P100 graphite fibers in a pure copper matrix. Thermal conductivity of the composites was measured from room temperature to 1073 K, and thermal expansion was measured from room temperature to 1050 K. The longitudinal thermal conductivity, parallel to the fiber direction, was comparable to pure copper. The transverse thermal conductivity, normal to the fiber direction, was less than that of pure copper and decreased with increasing fiber content. The longitudinal thermal expansion decreased with increasing fiber content. The transverse thermal expansion was greater than pure copper and nearly independent of fiber content.

Thermal energy storage apparatus, controllers and thermal energy storage control methods

DOEpatents

Hammerstrom, Donald J.

2016-05-03

Thermal energy storage apparatus, controllers and thermal energy storage control methods are described. According to one aspect, a thermal energy storage apparatus controller includes processing circuitry configured to access first information which is indicative of surpluses and deficiencies of electrical energy upon an electrical power system at a plurality of moments in time, access second information which is indicative of temperature of a thermal energy storage medium at a plurality of moments in time, and use the first and second information to control an amount of electrical energy which is utilized by a heating element to heat the thermal energy storage medium at a plurality of moments in time.

EFFECTS OF THE GRAM STAIN ON MICROSPHERES FROM THERMAL POLYAMINO ACIDS1

PubMed Central

Fox, Sidney W.; Yuyama, Shuhei

1963-01-01

Fox, Sidney W. (The Florida State University, Tallahassee) and Shuhei Yuyama. Effects of the Gram stain on microspheres from thermal polyamino acids. J. Bacteriol. 85:279–283. 1963.—Microspheres produced from acid proteinoid accept the Gram stain. The stain is negative, but microspheres produced from mixtures containing a sufficient proportion of lysine proteinoid stain positive. Microspheres produced from mixtures containing the appropriate proportions contain individuals which stain positive and others which stain negative. Images PMID:13959050

WMAP Observatory Thermal Design and On-Orbit Thermal Performance

NASA Technical Reports Server (NTRS)

Glazer, Stuart D.; Brown, Kimberly D.; Michalek, Theodore J.; Ancarrow, Walter C.

2003-01-01

The Wilkinson Microwave Anisotropy Probe (WMAP) observatory, launched June 30, 2001, is designed to measure the cosmic microwave background radiation with unprecedented precision and accuracy while orbiting the second Lagrange point (L2). The instrument cold stage must be cooled passively to <95K, and systematic thermal variations in selected instrument components controlled to less than 0.5 mK (rms) per spin period. This paper describes the thermal design and testing of the WMAP spacecraft and instrument. Flight thermal data for key spacecraft and instrument components are presented from launch through the first year of mission operations. Effects of solar flux variation due to the Earth's elliptical orbit about the sun, surface thermo-optical property degradations, and solar flares on instrument thermal stability are discussed.

Temperature Distribution and Thermal Performance of an Aquifer Thermal Energy Storage System

NASA Astrophysics Data System (ADS)

Ganguly, Sayantan

2017-04-01

Energy conservation and storage has become very crucial to make use of excess energy during times of future demand. Excess thermal energy can be captured and stored in aquifers and this technique is termed as Aquifer Thermal Energy Storage (ATES). Storing seasonal thermal energy in water by injecting it into subsurface and extracting in time of demand is the principle of an ATES system. Using ATES systems leads to energy savings, reduces the dependency on fossil fuels and thus leads to reduction in greenhouse gas emission. This study numerically models an ATES system to store seasonal thermal energy and evaluates the performance of it. A 3D thermo-hydrogeological numerical model for a confined ATES system is presented in this study. The model includes heat transport processes of advection, conduction and heat loss to confining rock media. The model also takes into account regional groundwater flow in the aquifer, geothermal gradient and anisotropy in the aquifer. Results show that thermal injection into the aquifer results in the generation of a thermal-front which grows in size with time. Premature thermal-breakthrough causes thermal interference in the system when the thermal-front reaches the production well and consequences in the fall of system performance and hence should be avoided. This study models the transient temperature distribution in the aquifer for different flow and geological conditions. This may be effectively used in designing an efficient ATES project by ensuring safety from thermal-breakthrough while catering to the energy demand. Based on the model results a safe well spacing is proposed. The thermal energy discharged by the system is determined and strategy to avoid the premature thermal-breakthrough in critical cases is discussed. The present numerical model is applied to simulate an experimental field study which is found to approximate the field results quite well.

Squeezed states and graviton-entropy production in the early universe

NASA Technical Reports Server (NTRS)

Giovannini, Massimo

1994-01-01

Squeezed states are a very useful framework for the quantum treatment of tensor perturbations (i.e. gravitons production) in the early universe. In particular, the non equilibrium entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic blackbody radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. Within the formalism of squeezed thermal states it is also possible to discuss the stimulated emission of gravitons from an initial thermal bath, under the action of the cosmic gravitational background field. We find that at low energy the graviton production is enhanced, if compared with spontaneous creation from the vacuum; as a consequence, the inflation scale must be lowered, in order not to exceed the observed CMB quadrupole anisotropy. This effect is important, in particular, for models based on a symmetry-breaking transition which require, as initial condition, a state of thermal equilibrium at temperatures higher than the inflation scale and in which inflation has a minimal duration.

Radiative bistability and thermal memory.

PubMed

Kubytskyi, Viacheslav; Biehs, Svend-Age; Ben-Abdallah, Philippe

2014-08-15

We predict the existence of a thermal bistability in many-body systems out of thermal equilibrium which exchange heat by thermal radiation using insulator-metal transition materials. We propose a writing-reading procedure and demonstrate the possibility to exploit the thermal bistability to make a volatile thermal memory. We show that this thermal memory can be used to store heat and thermal information (via an encoding temperature) for arbitrary long times. The radiative thermal bistability could find broad applications in the domains of thermal management, information processing, and energy storage.

Thermal-Wave Microscope

NASA Technical Reports Server (NTRS)

Jones, Robert E.; Kramarchuk, Ihor; Williams, Wallace D.; Pouch, John J.; Gilbert, Percy

1989-01-01

Computer-controlled thermal-wave microscope developed to investigate III-V compound semiconductor devices and materials. Is nondestructive technique providing information on subsurface thermal features of solid samples. Furthermore, because this is subsurface technique, three-dimensional imaging also possible. Microscope uses intensity-modulated electron beam of modified scanning electron microscope to generate thermal waves in sample. Acoustic waves generated by thermal waves received by transducer and processed in computer to form images displayed on video display of microscope or recorded on magnetic disk.

NASA/Goddard Thermal Technology Overview 2014

NASA Technical Reports Server (NTRS)

Butler, Daniel; Swanson, Theodore D.

2014-01-01

This presentation summarizes the current plans and efforts at NASA Goddard to develop new thermal control technology for anticipated future missions. It will also address some of the programmatic developments currently underway at NASA, especially with respect to the Technology Development Program at NASA. While funding for basic technology development is still scarce, significant efforts are being made in direct support of flight programs. New technology development continues to be driven by the needs of future missions, and applications of these technologies to current Goddard programs will be addressed. Many of these technologies also have broad applicability to DOD, DOE, and commercial programs. Partnerships have been developed with the Air Force, Navy, and various universities to promote technology development. In addition, technology development activities supported by internal research and development (IRAD) program, the Small Business Innovative Research (SBIR) program, and the NASA Engineering and Safety Center (NESC), are reviewed in this presentation. Specific technologies addressed include; two-phase systems applications and issues on NASA missions, latest developments of electro-hydrodynamically pumped systems, development of high electrical conductivity coatings, and various other research activities. New Technology program underway at NASA, although funding is limited center dot NASA/GSFC's primary mission of science satellite development is healthy and vibrant, although new missions are scarce - now have people on overhead working new missions and proposals center dot Future mission applications promise to be thermally challenging center dot Direct technology funding is still very restricted - Projects are the best source for direct application of technology - SBIR thermal subtopic resurrected in FY 14 - Limited Technology development underway via IRAD, NESC, other sources - Administrator pushing to revive technology and educational programs at NASA

Experimental Investigation of A Heat Pipe-Assisted Latent Heat Thermal Energy Storage System

NASA Astrophysics Data System (ADS)

Tiari, Saeed; Mahdavi, Mahboobe; Qiu, Songgang

2016-11-01

In the present work, different operation modes of a latent heat thermal energy storage system assisted by a heat pipe network were studied experimentally. Rubitherm RT55 enclosed by a vertical cylindrical container was used as the Phase Change Material (PCM). The embedded heat pipe network consisting of a primary heat pipe and an array of four secondary heat pipes were employed to transfer heat to the PCM. The primary heat pipe transports heat from the heat source to the heat sink. The secondary heat pipes transfer the extra heat from the heat source to PCM during charging process or retrieve thermal energy from PCM during discharging process. The effects of heat transfer fluid (HTF) flow rate and temperature on the thermal performance of the system were investigated for both charging and discharging processes. It was found that the HTF flow rate has a significant effect on the total charging time of the system. Increasing the HTF flow rate results in a remarkable increase in the system input thermal power. The results also showed that the discharging process is hardly affected by the HTF flow rate but HTF temperature plays an important role in both charging and discharging processes. The authors would like to acknowledge the financial supports by Temple University for the project.

Fossilization processes in siliceous thermal springs: trends in preservation along thermal gradients

NASA Technical Reports Server (NTRS)

Cady, S. L.; Farmer, J. D.

1996-01-01

To enhance our ability to extract palaeobiological and palaeoenvironmental information from ancient thermal spring deposits, we have studied the processes responsible for the development and preservation of stromatolites in modern subaerial thermal spring systems in Yellowstone National Park (USA). We investigated specimens collected from silica-depositing thermal springs along the thermal gradient using petrographic techniques and scanning electron microscopy. Although it is known that thermophilic cyanobacteria control the morphogenesis of thermal spring stromatolites below 73 degrees C, we have found that biofilms which contain filamentous thermophiles contribute to the microstructural development of subaerial geyserites that occur along the inner rims of thermal spring pools and geyser effluents. Biofilms intermittently colonize the surfaces of subaerial geyserites and provide a favoured substrate for opaline silica precipitation. We have also found that the preservation of biotically produced microfabrics of thermal spring sinters reflects dynamic balances between rates of population growth, decomposition of organic matter, silica deposition and early diagenesis. Major trends in preservation of thermophilic organisms along the thermal gradient are defined by differences in the mode of fossilization, including replacement, encrustation and permineralization.

Universality and Quantum Criticality of the One-Dimensional Spinor Bose Gas

NASA Astrophysics Data System (ADS)

PâÅ£u, Ovidiu I.; Klümper, Andreas; Foerster, Angela

2018-06-01

We investigate the universal thermodynamics of the two-component one-dimensional Bose gas with contact interactions in the vicinity of the quantum critical point separating the vacuum and the ferromagnetic liquid regime. We find that the quantum critical region belongs to the universality class of the spin-degenerate impenetrable particle gas which, surprisingly, is very different from the single-component case and identify its boundaries with the peaks of the specific heat. In addition, we show that the compressibility Wilson ratio, which quantifies the relative strength of thermal and quantum fluctuations, serves as a good discriminator of the quantum regimes near the quantum critical point. Remarkably, in the Tonks-Girardeau regime, the universal contact develops a pronounced minimum, reflected in a counterintuitive narrowing of the momentum distribution as we increase the temperature. This momentum reconstruction, also present at low and intermediate momenta, signals the transition from the ferromagnetic to the spin-incoherent Luttinger liquid phase and can be detected in current experiments with ultracold atomic gases in optical lattices.

Resonant Production of Sterile Neutrinos in the Early Universe

NASA Astrophysics Data System (ADS)

Gilbert, Lauren; Grohs, Evan; Fuller, George M.

2016-06-01

This study examines the cosmological impacts of a light resonantly produced sterile neutrino in the early universe. Such a neutrino could be produced through lepton number-driven Mikheyev-Smirnov-Wolfenstein (MSW) conversion of active neutrinos around big bang nucleosynthesis (BBN), resulting in a non-thermal spectrum of both sterile and electron neutrinos. During BBN, the neutron-proton ratio depends sensitively on the electron neutrino flux. If electron neutrinos are being converted to sterile neutrinos, this makes the n/p ratio a probe of possible new physics. We use observations of primordial Yp and D/H to place limits on this process.

Atom interferometry in space: Thermal management and magnetic shielding

NASA Astrophysics Data System (ADS)

Milke, Alexander; Kubelka-Lange, André; Gürlebeck, Norman; Rievers, Benny; Herrmann, Sven; Schuldt, Thilo; Braxmaier, Claus

2014-08-01

Atom interferometry is an exciting tool to probe fundamental physics. It is considered especially apt to test the universality of free fall by using two different sorts of atoms. The increasing sensitivity required for this kind of experiment sets severe requirements on its environments, instrument control, and systematic effects. This can partially be mitigated by going to space as was proposed, for example, in the Spacetime Explorer and Quantum Equivalence Principle Space Test (STE-QUEST) mission. However, the requirements on the instrument are still very challenging. For example, the specifications of the STE-QUEST mission imply that the Feshbach coils of the atom interferometer are allowed to change their radius only by about 260 nm or 2.6 × 10-4 % due to thermal expansion although they consume an average power of 22 W. Also Earth's magnetic field has to be suppressed by a factor of 105. We show in this article that with the right design such thermal and magnetic requirements can indeed be met and that these are not an impediment for the exciting physics possible with atom interferometers in space.

Thermalization and its mechanism for generic quantum isolated systems

NASA Astrophysics Data System (ADS)

Olshanii, Maxim; Dunjko, Vanja; Rigol, Marcos

2008-05-01

Time dynamics of isolated many-body quantum systems has long been an elusive subject, perhaps most urgently needed in the foundations of quantum statistical mechanics. In generic systems, one expects the nonequilibrium dynamics to lead to thermalization: a relaxation to states where the values of macroscopic quantities are stationary, universal with respect to widely differing initial conditions, and predictable through the time-tested recipe of statistical mechanics. The relaxation mechanism is not obvious, however; dynamical chaos cannot play the key role as it does in classical systems since quantum evolution is linear. Here we demonstrateootnotetextM. Rigol, V. Dunjko, and M. Olshanii, to appear in Nature (2008), using the results of an ab initio numerical experiment with 5 hard-core bosons moving in a 5x5 lattice, that in quantum systems thermalization happens not in course of time evolution but instead at the level of individual eigenstates, as first proposed by DeutschootnotetextJ. M. Deutsch, Phys.Rev. A 43, 2046 (1991) and SrednickiootnotetextM. Srednicki, Phys. Rev. E 50, 888 (1994).

Overview of thermal conductivity models of anisotropic thermal insulation materials

NASA Astrophysics Data System (ADS)

Skurikhin, A. V.; Kostanovsky, A. V.

2017-11-01

Currently, the most of existing materials and substances under elaboration are anisotropic. It makes certain difficulties in the study of heat transfer process. Thermal conductivity of the materials can be characterized by tensor of the second order. Also, the parallelism between the temperature gradient vector and the density of heat flow vector is violated in anisotropic thermal insulation materials (TIM). One of the most famous TIM is a family of integrated thermal insulation refractory material («ITIRM»). The main component ensuring its properties is the «inflated» vermiculite. Natural mineral vermiculite is ground into powder state, fired by gas burner for dehydration, and its precipitate is then compressed. The key feature of thus treated batch of vermiculite is a package structure. The properties of the material lead to a slow heating of manufactured products due to low absorption and high radiation reflection. The maximum of reflection function is referred to infrared spectral region. A review of current models of heat propagation in anisotropic thermal insulation materials is carried out, as well as analysis of their thermal and optical properties. A theoretical model, which allows to determine the heat conductivity «ITIRM», can be useful in the study of thermal characteristics such as specific heat capacity, temperature conductivity, and others. Materials as «ITIRM» can be used in the metallurgy industry, thermal energy and nuclear power-engineering.

RADYN Simulations of Non-thermal and Thermal Models of Ellerman Bombs

NASA Astrophysics Data System (ADS)

Hong, Jie; Carlsson, Mats; Ding, M. D.

2017-08-01

Ellerman bombs (EBs) are brightenings in the Hα line wings that are believed to be caused by magnetic reconnection in the lower atmosphere. To study the response and evolution of the chromospheric line profiles, we perform radiative hydrodynamic simulations of EBs using both non-thermal and thermal models. Overall, these models can generate line profiles that are similar to observations. However, in non-thermal models we find dimming in the Hα line wings and continuum when the heating begins, while for the thermal models dimming occurs only in the Hα line core, and with a longer lifetime. This difference in line profiles can be used to determine whether an EB is dominated by non-thermal heating or thermal heating. In our simulations, if a higher heating rate is applied, then the Hα line will be unrealistically strong and there are still no clear UV burst signatures.

A novel technique to monitor thermal discharges using thermal infrared imaging.

PubMed

Muthulakshmi, A L; Natesan, Usha; Ferrer, Vincent A; Deepthi, K; Venugopalan, V P; Narasimhan, S V

2013-09-01

Coastal temperature is an important indicator of water quality, particularly in regions where delicate ecosystems sensitive to water temperature are present. Remote sensing methods are highly reliable for assessing the thermal dispersion. The plume dispersion from the thermal outfall of the nuclear power plant at Kalpakkam, on the southeast coast of India, was investigated from March to December 2011 using thermal infrared images along with field measurements. The absolute temperature as provided by the thermal infrared (TIR) images is used in the Arc GIS environment for generating a spatial pattern of the plume movement. Good correlation of the temperature measured by the TIR camera with the field data (r(2) = 0.89) make it a reliable method for the thermal monitoring of the power plant effluents. The study portrays that the remote sensing technique provides an effective means of monitoring the thermal distribution pattern in coastal waters.

Thermal tolerance breadths among groundwater crustaceans living in a thermally constant environment.

PubMed

Mermillod-Blondin, F; Lefour, C; Lalouette, L; Renault, D; Malard, F; Simon, L; Douady, C J

2013-05-01

The climate variability hypothesis assumes that the thermal tolerance breadth of a species is primarily determined by temperature variations experienced in its environment. If so, aquatic invertebrates living in thermally buffered environments would be expected to exhibit narrow thermal tolerance breadths (stenothermy). We tested this prediction by studying the thermal physiology of three isopods (Asellidae, Proasellus) colonizing groundwater habitats characterized by an annual temperature amplitude of less than 1°C. The species responses to temperature variation were assessed in the laboratory using five physiological variables: survival, locomotor activity, aerobic respiration, immune defense and concentrations of total free amino acids and sugars. The three species exhibited contrasted thermal physiologies, although all variables were not equally informative. In accordance with the climate variability hypothesis, two species were extremely sensitive even to moderate changes in temperature (2°C) below and above their habitat temperature. In contrast, the third species exhibited a surprisingly high thermal tolerance breadth (11°C). Differences in response to temperature variation among Proasellus species indicated that their thermal physiology was not solely shaped by the current temperature seasonality in their natural habitats. More particularly, recent gene flow among populations living in thermally constant yet contrasted habitats might explain the occurrence of eurytherm species in thermally buffered environments.

Microscale solid-state thermal diodes enabling ambient temperature thermal circuits for energy applications.

PubMed

Wang, Song; Cottrill, Anton L; Kunai, Yuichiro; Toland, Aubrey R; Liu, Pingwei; Wang, Wen-Jun; Strano, Michael S

2017-05-24

Thermal diodes, or devices that transport thermal energy asymmetrically, analogous to electrical diodes, hold promise for thermal energy harvesting and conservation, as well as for phononics or information processing. The junction of a phase change material and phase invariant material can form a thermal diode; however, there are limited constituent materials available for a given target temperature, particularly near ambient. In this work, we demonstrate that a micro and nanoporous polystyrene foam can house a paraffin-based phase change material, fused to PMMA, to produce mechanically robust, solid-state thermal diodes capable of ambient operation with Young's moduli larger than 11.5 MPa and 55.2 MPa above and below the melting transition point, respectively. Moreover, the composites show significant changes in thermal conductivity above and below the melting point of the constituent paraffin and rectification that is well-described by our previous theory and the Maxwell-Eucken model. Maximum thermal rectifications range from 1.18 to 1.34. We show that such devices perform reliably enough to operate in thermal diode bridges, dynamic thermal circuits capable of transforming oscillating temperature inputs into single polarity temperature differences - analogous to an electrical diode bridge with widespread implications for transient thermal energy harvesting and conservation. Overall, our approach yields mechanically robust, solid-state thermal diodes capable of engineering design from a mathematical model of phase change and thermal transport, with implications for energy harvesting.

Thermal analysis of a prototype cryogenic polarization modulator for use in a space-borne CMB polarization experiment

NASA Astrophysics Data System (ADS)

Iida, T.; Sakurai, Y.; Matsumura, T.; Sugai, H.; Imada, H.; Kataza, H.; Ohsaki, H.; Hazumi, M.; Katayama, N.; Yamamoto, R.; Utsunomiya, S.; Terao, Y.

2017-12-01

We report a thermal analysis of a polarization modulator unit (PMU) for use in a space-borne cosmic microwave background (CMB) project. A measurement of the CMB polarization allows us to probe the physics of early universe, and that is the best method to test the cosmic inflation experimentally. One of the key instruments for this science is to use a halfwave plate (HWP) based polarization modulator. The HWP is required to rotate continuously at about 1 Hz below 10 K to minimize its own thermal emission to a detector system. The rotating HWP system at the cryogenic environment can be realized by using a superconducting magnetic bearing (SMB) without significant heat dissipation by mechanical friction. While the SMB achieves the smooth rotation due to the contactless bearing, an estimation of a levitating HWP temperature becomes a challenge. We manufactured a one-eighth scale prototype model of PMU and built a thermal model. We verified our thermal model with the experimental data. We forecasted the projected thermal performance of PMU for a full-scale model based on the thermal model. From this analysis, we discuss the design requirement toward constructing the full-scale model for use in a space environment such as a future CMB satellite mission, LiteBIRD.

The thermal inertia of Mars from the Mars Global Surveyor Thermal Emission Spectrometer

USGS Publications Warehouse

Jakosky, Bruce M.; Mellon, Michael T.; Kieffer, Hugh H.; Christensen, Philip R.; Varnes, E. Stacy; Lee, Steven W.

2000-01-01

We have used Mars Global Surveyor (MGS) Thermal Emission Spectrometer thermal emission measurements to derive the thermal inertia of the Martian surface at the ∼100-km spatial scale. We have validated the use of nighttime-only measurements to derive thermal inertia as well as the use of a single wavelength band versus bolometric thermal emission measurements. We have also reanalyzed the Viking Infrared Thermal Mapper data set in a similar manner in order to allow a direct comparison between the two. Within the uncertainties of the fit of the data to the model, and the uncertainties inherent in the model, the thermal inertia has not changed substantially in the 21 years between the Viking and the MGS measurements. Although some differences are seen, they are most likely due to changes in albedo during the intervening years or to residual effects of airborne dust that are not fully accounted for in the thermal models. The thermal inertia values that we derive, between about 24 and 800 J m-2 s-1/2 K-1, are thought to better represent the actual thermal inertia of the Martian surface than previous estimates.

Observing the Non-Thermal Universe with the Highest Energy Photons

NASA Astrophysics Data System (ADS)

Dingus, Brenda L.; HAWC, VERITAS, CTA

2016-01-01

Astrophysical sources of relativistic particles radiate gamma rays to such high energies that they can be detected from the ground. The existence of high energy gamma rays implies that even higher energy particles are being accelerated placing strong constraints on these non-thermal accelerators. Within our galaxy, TeV gamma rays have been detected from supernova remnants, pulsar wind nebula, x-ray binaries and some yet to be identified sources in the Galactic plane. In addition, these gamma rays have sufficient energy to be attenuated by the interaction with infrared photons producing an electron-positron pair. Thus the spectrum of gamma rays can also constrain the infrared photon density, which for distant extragalactic sources is a direct probe of cosmology. The known extragalactic TeV sources are primarily the blazer class of active galactic nuclei. And TeV gamma rays might even be produced by annihilating dark matter.The US currently supports two ground-based gamma-ray observatories—HAWC and VERITAS—and NSF is developing a prototype for the international Cherenkov Telescope Array (CTA) observatory. The HAWC (High Altitude Water Cherenkov) observatory just began operation of the full detector in March 2015 and with its wide field of view scans ~2/3 of the sky each day for TeV sources. VERITAS (Very EneRgetic Imaging Telescope Array System) is an array of four imaging atmospheric Cherenkov telescopes that follows individual sources to produce lightcurves and spectra from 85 GeV to > 30 TeV. The combination of both a survey and pointed observatory is very complementary with a broad scientific reach that includes the study of extragalactic and Galactic objects as well as the search for astrophysical signatures of dark matter and the measurement of cosmic rays. I will present the current view of the TeV sky and the latest results from HAWC and VERITAS as well as plans for CTA.

Thermal Properties of Oxides With Magnetoplumbite Structure for Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

2007-01-01

Oxides having magnetoplumbite structure are promising candidate materials for applications as high temperature thermal barrier coatings because of their high thermal stability, high thermal expansion, and low thermal conductivity. In this study, powders of LaMgAl11O19, GdMgAl11O19, SmMgAl11O19, and Gd0.7Yb0.3MgAl11O19 magnetoplumbite oxides were synthesized by citric acid sol-gel method and hot pressed into disk specimens. The thermal expansion coefficients (CTE) of these oxide materials were measured from room temperature to 1500 C. The average CTE value was found to be approx.9.6x10(exp -6)/C. Thermal conductivity of these magnetoplumbite-based oxide materials was also evaluated using steady-state laser heat flux test method. The effects of doping on thermal properties were also examined. Thermal conductivity of the doped Gd0.7Yb0.3MgAl11O19 composition was found to be lower than that of the undoped GdMgAl11O19. In contrast, thermal expansion coefficient was found to be independent of the oxide composition and appears to be controlled by the magnetoplumbite crystal structure. Thermal conductivity testing of LaMgAl11O19 and LaMnAl11O19 magnetoplumbite oxide coatings plasma sprayed on NiCrAlY/Rene N5 superalloy substrates indicated resistance of these coatings to sintering even at temperatures as high as 1600 C.

Atmospheric effects on the mapping of Martian thermal inertia and thermally derived albedo

NASA Technical Reports Server (NTRS)

Hayashi, J. N.; Jakosky, B. M.; Haberle, R. M.

1994-01-01

The most widely used thermal inertia data for Mars assumes the atmospheric contribution is constant and equal to 2 percent of the maximum solar insolation. Haberle and Jakosky investigated the effect of including a dusty CO2 atmosphere and sensible heat exchange with the surface on thermal inertia. We recently utilized Haberle and Jakosky's coupled surface-atmosphere model to investigate the effects of such an atmosphere on the thermally derived albedo. The thermally derived albedo is the albedo which, together with the thermal inertia, provides model surface temperatures which best match the observed temperatures. New maps are presented of thermal inertia and thermally derived albedo which incorporate dust opacities derived from IRTM data.

Frequency-resolved Raman for transient thermal probing and thermal diffusivity measurement

DOE PAGES

Wang, Tianyu; Xu, Shen; Hurley, David H.; ...

2015-12-18

Steady state Raman has been widely used for temperature probing and thermal conductivity/conductance measurement in combination with temperature coefficient calibration. In this work, a new transient Raman thermal probing technique: frequency-resolved Raman (FR-Raman) is developed for probing the transient thermal response of materials and measuring their thermal diffusivity. The FR-Raman uses an amplitude modulated square-wave laser for simultaneous material heating and Raman excitation. The evolution profile of Raman properties: intensity, Raman wavenumber, and emission, against frequency are measured experimentally and reconstructed theoretically. They are used for fitting to determine the thermal diffusivity of the material under test. A Si cantilevermore » is used to investigate the capacity of this new technique. The cantilever’s thermal diffusivity is determined as 9.57 × 10 -5 m 2/s, 11.00 × 10 -5 m 2/s and 9.02 × 10 -5 m 2/s by fitting the Raman intensity, wavenumber and emission. The deviation from the reference value is largely attributed to thermal stress-induced material deflection and Raman drift, which could be significantly suppressed by using a higher sensitivity Raman spectrometer with lower laser energy. As a result, the FR-Raman provides a novel way for transient thermal characterization of materials with a ?m spatial resolution.« less

Passive activity observation (PAO) method to estimate outdoor thermal adaptation in public space: case studies in Australian cities.

PubMed

Sharifi, Ehsan; Boland, John

2018-06-18

Outdoor thermal comfort is influenced by people's climate expectations, perceptions and adaptation capacity. Varied individual response to comfortable or stressful thermal environments results in a deviation between actual outdoor thermal activity choices and those predicted by thermal comfort indices. This paper presents a passive activity observation (PAO) method for estimating contextual limits of outdoor thermal adaptation. The PAO method determines which thermal environment result in statistically meaningful changes may occur in outdoor activity patterns, and it estimates thresholds of outdoor thermal neutrality and limits of thermal adaptation in public space based on activity observation and microclimate field measurement. Applications of the PAO method have been demonstrated in Adelaide, Melbourne and Sydney, where outdoor activities were analysed against outdoor thermal comfort indices between 2013 and 2014. Adjusted apparent temperature (aAT), adaptive predicted mean vote (aPMV), outdoor standard effective temperature (OUT_SET), physiological equivalent temperature (PET) and universal thermal comfort index (UTCI) are calculated from the PAO data. Using the PAO method, the high threshold of outdoor thermal neutrality was observed between 24 °C for optional activities and 34 °C for necessary activities (UTCI scale). Meanwhile, the ultimate limit of thermal adaptation in uncontrolled public spaces is estimated to be between 28 °C for social activities and 48 °C for necessary activities. Normalised results indicate that city-wide high thresholds for outdoor thermal neutrality vary from 25 °C in Melbourne to 26 °C in Sydney and 30 °C in Adelaide. The PAO method is a relatively fast and localised method for measuring limits of outdoor thermal adaptation and effectively informs urban design and policy making in the context of climate change.

Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields

NASA Astrophysics Data System (ADS)

Minoda, Teppei; Hasegawa, Kenji; Tashiro, Hiroyuki; Ichiki, Kiyotomo; Sugiyama, Naoshi

2017-12-01

The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zel'dovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as P (k )∝B1Mpc 2knB , we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton y -parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton y -parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast on small scale just after the recombination epoch. These facts result in making the anisotropies of the CMB temperature on small scales, and we find that the signal goes up to 10 μ K2 around ℓ˜106 with B1 Mpc=0.1 nG and nB=0.0 . Therefore, CMB measurements on such small scales may provide a hint for the existence of the PMFs.

Tunable thermal link

DOEpatents

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.

Cosmological moduli and the post-inflationary universe: A critical review

NASA Astrophysics Data System (ADS)

Kane, Gordon; Sinha, Kuver; Watson, Scott

2015-06-01

We critically review the role of cosmological moduli in determining the post-inflationary history of the universe. Moduli are ubiquitous in string and M-theory constructions of beyond the Standard Model physics, where they parametrize the geometry of the compactification manifold. For those with masses determined by supersymmetry (SUSY) breaking this leads to their eventual decay slightly before Big Bang nucleosynthesis (BBN) (without spoiling its predictions). This results in a matter dominated phase shortly after inflation ends, which can influence baryon and dark matter genesis, as well as observations of the cosmic microwave background (CMB) and the growth of large-scale structure. Given progress within fundamental theory, and guidance from dark matter and collider experiments, nonthermal histories have emerged as a robust and theoretically well-motivated alternative to a strictly thermal one. We review this approach to the early universe and discuss both the theoretical challenges and the observational implications.

High-Resolution Thermal Inertia Mapping from the Mars Global Surveyor Thermal Emission Spectrometer

USGS Publications Warehouse

Mellon, M.T.; Jakosky, B.M.; Kieffer, H.H.; Christensen, P.R.

2000-01-01

High-resolution thermal inertia mapping results are presented, derived from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) observations of the surface temperature of Mars obtained during the early portion of the MGS mapping mission. Thermal inertia is the key property controlling the diurnal surface temperature variations, and is dependent on the physical character of the top few centimeters of the surface. It represents a complex combination of particle size, rock abundance, exposures of bedrock, and degree of induration. In this work we describe the derivation of thermal inertia from TES data, present global scale analysis, and place these results into context with earlier work. A global map of nighttime thermal-bolometer-based thermal inertia is presented at 14?? per pixel resolution, with approximately 63% coverage between 50??S and 70??N latitude. Global analysis shows a similar pattern of high and low thermal inertia as seen in previous Viking low-resolution mapping. Significantly more detail is present in the high-resolution TES thermal inertia. This detail represents horizontal small-scale variability in the nature of the surface. Correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate-to-high thermal inertia and intermediate albedo. This new unit has a modal peak thermal inertia of 180-250 J m-2 K-1 s-12 and a narrow range of albedo near 0.24. The unit, covering a significant fraction of the surface, typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material. Local 3-km-resolution maps are also presented as examples of eolian, fluvial, and volcanic geology. Some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain; thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size. Outflow channels and valleys consistently show higher thermal inertias than the

Thermal conductance of space suit insulations, thermal micrometeroid garments, and other insulations

NASA Technical Reports Server (NTRS)

Richardson, D. L.; Stevens, J. M.

1976-01-01

The thermal protection capabilities of development and operational thermal micrometeroid garments and other insulations were evaluated. The relationship among sample thermal conductance, surface temperature, and compressive loads was empirically defined.

Monte Carlo Transport for Electron Thermal Transport

NASA Astrophysics Data System (ADS)

Chenhall, Jeffrey; Cao, Duc; Moses, Gregory

2015-11-01

The iSNB (implicit Schurtz Nicolai Busquet multigroup electron thermal transport method of Cao et al. is adapted into a Monte Carlo transport method in order to better model the effects of non-local behavior. The end goal is a hybrid transport-diffusion method that combines Monte Carlo Transport with a discrete diffusion Monte Carlo (DDMC). The hybrid method will combine the efficiency of a diffusion method in short mean free path regions with the accuracy of a transport method in long mean free path regions. The Monte Carlo nature of the approach allows the algorithm to be massively parallelized. Work to date on the method will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

Thermal Coatings Seminar Series Training Part 1: Properties of Thermal Coatings

NASA Technical Reports Server (NTRS)

Triolo, Jack

2015-01-01

This course will present an overview of a variety of thermal coatings-related topics, including: coating types and availability, thermal properties measurements, environmental testing (lab and in-flight), environmental impacts, contamination impacts, contamination liabilities, determination of BOLEOL values, and what does specularity mean to the thermal engineer.

RADYN Simulations of Non-thermal and Thermal Models of Ellerman Bombs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Jie; Ding, M. D.; Carlsson, Mats, E-mail: dmd@nju.edu.cn

Ellerman bombs (EBs) are brightenings in the H α line wings that are believed to be caused by magnetic reconnection in the lower atmosphere. To study the response and evolution of the chromospheric line profiles, we perform radiative hydrodynamic simulations of EBs using both non-thermal and thermal models. Overall, these models can generate line profiles that are similar to observations. However, in non-thermal models we find dimming in the H α line wings and continuum when the heating begins, while for the thermal models dimming occurs only in the H α line core, and with a longer lifetime. This differencemore » in line profiles can be used to determine whether an EB is dominated by non-thermal heating or thermal heating. In our simulations, if a higher heating rate is applied, then the H α line will be unrealistically strong and there are still no clear UV burst signatures.« less

Synthesis and Magnetic, Thermal, and Electrical Measurements on Complex non-Cuprate Superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, Laurence L

2006-02-27

The project investigated superconductivity in non-cuprate materials with critical temperatures, T{sub c}, in excess of 20 K in order to understand the thermodynamics of several of these materials. The project is a cooperative effort between investigators at Southern University (SU), Louisiana State University (LSU), and Los Alamos National Laboratory (LANL). It involved synthesis of high quality samples, and subsequent detailed magnetic, thermal and electrical measurements on them. The project provided a PhD Thesis research experience and training for a graduate student, Ms. Robin Macaluso. High quality, single crystal samples were synthesized by Ms. Macaluso under the direction of one ofmore » the CO-PIS, John Sarao, during the summer while she was a visitor at LANL being supported by this grant. On these samples magnetic measurements were performed at SU, thermal and electrical measurements were made in the LSU Physics and Astronomy Department. The crystallographic properties were determined in the LSU Chemistry Department by Ms. Macaluso under the direction of her dissertation advisor, Dr. Julia Chan. Additional high field magnetic measurements on other samples were performed at the National High Magnetic Field Laboratory (NHMFL) both in Tallahassee and at LANL. These measurements involved another graduate student, Umit Alver, who used some of the measurements as part of his PhD dissertation in Physics at LSU.« less

Red River Waterway Thermal Studies. Report 2. Thermal Stress Analyses

DTIC Science & Technology

1991-12-01

stress relaxation, q. Shrinkage of the concrete, and . Thermal properties of the concrete including coefficient of thermal expansion , specific heat...Finite-Element Code 12. The thermal stress analyses in this investigation was performed using ABAQUS , a general-purpose, heat-transfer and structural...model (the UMAT 9 subroutine discussed below) may be incorporated as an external subroutine linked to the ABAQUS library. 14. In order to model the

Impact of Photovoltaic Canopy Shade on Outdoor Thermal Comfort in a Hot Desert City

NASA Astrophysics Data System (ADS)

Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

2016-04-01

Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade on thermal comfort through microclimate observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. Six stationary sensors under solar canopies and in nearby sun-exposed and tree-shaded locations monitored 5-min temperature and humidity for a year. On selected clear calm days representative of each season, we conducted hourly microclimate transects from 7:00AM to 6:00PM and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on the Likert scale, increasing thermal comfort in all seasons except winter. The shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shade are equally efficient in semi-arid desert environments. Globe temperature explained 50% of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors include adaptation level, gender, thermal comfort vote, thermal preference, season, and time of day. A regression of perceived comfort on Physiological Equivalent Temperature yielded a neutral temperature of 28.6°C. The acceptable comfort range was 19.1°C-38.1°C with a preferred temperature of 20.8°C. Respondents exposed to above neutral temperatures felt more comfortable if they had been in air-conditioning 5 minutes prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas.

Interfacial thermal resistance and thermal rectification in carbon nanotube film-copper systems.

PubMed

Duan, Zheng; Liu, Danyang; Zhang, Guang; Li, Qingwei; Liu, Changhong; Fan, Shoushan

2017-03-02

Thermal rectification occurring at interfaces is an important research area, which contains deep fundamental physics and has extensive application prospects. In general, the measurement of interfacial thermal rectification is based on measuring interfacial thermal resistance (ITR). However, ITRs measured via conventional methods cannot avoid extra thermal resistance asymmetry due to the contact between the sample and the thermometer. In this study, we employed a non-contact infrared thermal imager to monitor the temperature of super-aligned carbon nanotube (CNT) films and obtain the ITRs between the CNT films and copper. The ITRs along the CNT-copper direction and the reverse direction are in the ranges of 2.2-3.6 cm 2 K W -1 and 9.6-11.9 cm 2 K W -1 , respectively. The obvious difference in the ITRs of the two directions shows a significant thermal rectification effect, and the rectifying coefficient ranges between 0.57 and 0.68. The remarkable rectification factor is extremely promising for the manufacture of thermal transistors with a copper/CNT/copper structure and further thermal logic devices. Moreover, our method could be extended to other 2-dimensional materials, such as graphene and MoS 2 , for further explorations.

Development of thermal model to analyze thermal flux distribution in thermally enhanced machining of high chrome white cast iron

NASA Astrophysics Data System (ADS)

Ravi, A. M.; Murigendrappa, S. M.

2018-04-01

In recent times, thermally enhanced machining (TEM) slowly gearing up to cut hard metals like high chrome white cast iron (HCWCI) which were impossible in conventional procedures. Also setting up of suitable cutting parameters and positioning of the heat source against the work appears to be critical in order to enhance the machinability characteristics of the work material. In this research work, the Oxy - LPG flame was used as the heat source and HCWCI as the workpiece. ANSYS-CFD-Flow software was used to develop the transient thermal model to analyze the thermal flux distribution on the work surface during TEM of HCWCI using Cubic boron nitride (CBN) tools. Non-contact type Infrared thermo sensor was used to measure the surface temperature continuously at different positions, and is validated with the thermal model results. The result confirms thermal model is a better predictive tool for thermal flux distribution analysis in TEM process.

Thermal Diffusivity Measurement for Thermal Spray Coating Attached to Substrate Using Laser Flash Method

NASA Astrophysics Data System (ADS)

Akoshima, Megumi; Tanaka, Takashi; Endo, Satoshi; Baba, Tetsuya; Harada, Yoshio; Kojima, Yoshitaka; Kawasaki, Akira; Ono, Fumio

2011-11-01

Ceramic-based thermal barrier coatings are used as heat and wear shields of gas turbine blades. There is a strong need to evaluate the thermal conductivity of coating for thermal design and use. The thermal conductivity of a bulk material is obtained as the product of thermal diffusivity, specific heat capacity, and density above room temperature in many cases. Thermal diffusivity and thermal conductivity are unique for a given material because they are sensitive to the structure of the material. Therefore, it is important to measure them in each sample. However it is difficult to measure the thermal diffusivity and thermal conductivity of coatings because coatings are attached to substrates. In order to evaluate the thermal diffusivity of a coating attached to the substrate, we have examined the laser flash method with the multilayer model on the basis of the response function method. We carried out laser flash measurements in layered samples composed of a CoNiCrAlY bond coating and a 8YSZ top coating by thermal spraying on a Ni-based superalloy substrate. It was found that the procedure using laser flash method with the multilayer model is useful for the thermal diffusivity evaluation of a coating attached to a substrate.

A report on the use of thermal scanner data in an operational program for monitoring apparent rooftop temperatures

NASA Technical Reports Server (NTRS)

Bjorklund, J.; Schmer, F. A.; Isakson, R. E.

1975-01-01

CENGAS, a division of Central Telephone and Utilities Corporation in cooperation with the Remote Sensing Institute, South Dakota State University, is using airborne thermal scanner data to monitor relative rooftop temperatures. Four Nebraska communities and one South Dakota community were surveyed by the Remote Sensing Institute for CENGAS. Thermal scanner data were converted to a film format and the resultant imagery has been successfully employed by CENGAS. The program places emphasis on heat losses resulting from inadequate home insulation, offers CENGAS customers the opportunity to observe a thermogram of their rooftop, and assists homeowners in evaluating insulation needs.

Thermal treatment wall

DOEpatents

Aines, Roger D.; Newmark, Robin L.; Knauss, Kevin G.

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.

Variable pressure thermal insulating jacket

DOEpatents

Nelson, Paul A.; Malecha, Richard F.; Chilenskas, Albert A.

1994-01-01

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

Remote Sensing of Soil Moisture: A Comparison of Optical and Thermal Methods

NASA Astrophysics Data System (ADS)

Foroughi, H.; Naseri, A. A.; Boroomandnasab, S.; Sadeghi, M.; Jones, S. B.; Tuller, M.; Babaeian, E.

2017-12-01

Recent technological advances in satellite and airborne remote sensing have provided new means for large-scale soil moisture monitoring. Traditional methods for soil moisture retrieval require thermal and optical RS observations. In this study we compared the traditional trapezoid model parameterized based on the land surface temperature - normalized difference vegetation index (LST-NDVI) space with the recently developed optical trapezoid model OPTRAM parameterized based on the shortwave infrared transformed reflectance (STR)-NDVI space for an extensive sugarcane field located in Southwestern Iran. Twelve Landsat-8 satellite images were acquired during the sugarcane growth season (April to October 2016). Reference in situ soil moisture data were obtained at 22 locations at different depths via core sampling and oven-drying. The obtained results indicate that the thermal/optical and optical prediction methods are comparable, both with volumetric moisture content estimation errors of about 0.04 cm3 cm-3. However, the OPTRAM model is more efficient because it does not require thermal data and can be universally parameterized for a specific location, because unlike the LST-soil moisture relationship, the reflectance-soil moisture relationship does not significantly vary with environmental variables (e.g., air temperature, wind speed, etc.).

Thermal properties of graphite oxide, thermally reduced graphene and chemically reduced graphene

NASA Astrophysics Data System (ADS)

Jankovský, Ondřej; Sedmidubský, David; Lojka, Michal; Sofer, Zdeněk

2017-07-01

We compared thermal behavior and other properties of graphite oxide, thermally reduced graphene and chemically reduced graphene. Graphite was oxidized according to the Hofmann method using potassium chlorate as oxidizing agent in strongly acidic environment. In the next step, the formed graphite oxide was chemically or thermally reduced yielding graphene. The mechanism of thermal reduction was studied using STA-MS. Graphite oxide and both thermally and chemically reduced graphenes were analysed by SEM, EDS, elemental combustion analysis, XPS, Raman spectroscopy, XRD and BET. These findings will help for the large scale production of graphene with appropriate chemical composition.

Thermalized axion inflation

NASA Astrophysics Data System (ADS)

Ferreira, Ricardo Z.; Notari, Alessio

2017-09-01

We analyze the dynamics of inflationary models with a coupling of the inflaton phi to gauge fields of the form phi F tilde F/f, as in the case of axions. It is known that this leads to an instability, with exponential amplification of gauge fields, controlled by the parameter ξ= dot phi/(2fH), which can strongly affect the generation of cosmological perturbations and even the background. We show that scattering rates involving gauge fields can become larger than the expansion rate H, due to the very large occupation numbers, and create a thermal bath of particles of temperature T during inflation. In the thermal regime, energy is transferred to smaller scales, radically modifying the predictions of this scenario. We thus argue that previous constraints on ξ are alleviated. If the gauge fields have Standard Model interactions, which naturally provides reheating, they thermalize already at ξgtrsim2.9, before perturbativity constraints and also before backreaction takes place. In absence of SM interactions (i.e. for a dark photon), we find that gauge fields and inflaton perturbations thermalize if ξgtrsim3.4 however, observations require ξgtrsim6, which is above the perturbativity and backreaction bounds and so a dedicated study is required. After thermalization, though, the system should evolve non-trivially due to the competition between the instability and the gauge field thermal mass. If the thermal mass and the instabilities equilibrate, we expect an equilibrium temperature of Teq simeq ξ H/bar g where bar g is the effective gauge coupling. Finally, we estimate the spectrum of perturbations if phi is thermal and find that the tensor to scalar ratio is suppressed by H/(2T), if tensors do not thermalize.

Thermalized axion inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, Ricardo Z.; Notari, Alessio, E-mail: rferreira@icc.ub.edu, E-mail: notari@ub.edu

2017-09-01

We analyze the dynamics of inflationary models with a coupling of the inflaton φ to gauge fields of the form φ F F-tilde / f , as in the case of axions. It is known that this leads to an instability, with exponential amplification of gauge fields, controlled by the parameter ξ= φ-dot /(2 fH ), which can strongly affect the generation of cosmological perturbations and even the background. We show that scattering rates involving gauge fields can become larger than the expansion rate H , due to the very large occupation numbers, and create a thermal bath of particlesmore » of temperature T during inflation. In the thermal regime, energy is transferred to smaller scales, radically modifying the predictions of this scenario. We thus argue that previous constraints on ξ are alleviated. If the gauge fields have Standard Model interactions, which naturally provides reheating, they thermalize already at ξ∼>2.9, before perturbativity constraints and also before backreaction takes place. In absence of SM interactions (i.e. for a dark photon), we find that gauge fields and inflaton perturbations thermalize if ξ∼>3.4; however, observations require ξ∼>6, which is above the perturbativity and backreaction bounds and so a dedicated study is required. After thermalization, though, the system should evolve non-trivially due to the competition between the instability and the gauge field thermal mass. If the thermal mass and the instabilities equilibrate, we expect an equilibrium temperature of T {sub eq} ≅ ξ H / g-bar where g-bar is the effective gauge coupling. Finally, we estimate the spectrum of perturbations if φ is thermal and find that the tensor to scalar ratio is suppressed by H /(2 T ), if tensors do not thermalize.« less

Battery Thermal Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keyser, Matthew A

The operating temperature is critical in achieving the right balance between performance, cost, and life for both Li-ion batteries and ultracapacitors. The chemistries of advanced energy-storage devices - such as lithium-based batteries - are very sensitive to operating temperature. High temperatures degrade batteries faster while low temperatures decrease their power and capacity, affecting vehicle range, performance, and cost. Understanding heat generation in battery systems - from the individual cells within a module, to the inter-connects between the cells, and across the entire battery system - is imperative for designing effective thermal-management systems and battery packs. At NREL, we have developedmore » unique capabilities to measure the thermal properties of cells and evaluate thermal performance of battery packs (air or liquid cooled). We also use our electro-thermal finite element models to analyze the thermal performance of battery systems in order to aid battery developers with improved thermal designs. NREL's tools are used to meet the weight, life, cost, and volume goals set by the U.S. Department of Energy for electric drive vehicles.« less

THERMUS—A thermal model package for ROOT

NASA Astrophysics Data System (ADS)

Wheaton, S.; Cleymans, J.; Hauer, M.

2009-01-01

THERMUS is a package of C++ classes and functions allowing statistical-thermal model analyses of particle production in relativistic heavy-ion collisions to be performed within the ROOT framework of analysis. Calculations are possible within three statistical ensembles; a grand-canonical treatment of the conserved charges B, S and Q, a fully canonical treatment of the conserved charges, and a mixed-canonical ensemble combining a canonical treatment of strangeness with a grand-canonical treatment of baryon number and electric charge. THERMUS allows for the assignment of decay chains and detector efficiencies specific to each particle yield, which enables sensible fitting of model parameters to experimental data. Program summaryProgram title: THERMUS, version 2.1 Catalogue identifier: AEBW_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBW_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 17 152 No. of bytes in distributed program, including test data, etc.: 93 581 Distribution format: tar.gz Programming language: C++ Computer: PC, Pentium 4, 1 GB RAM (not hardware dependent) Operating system: Linux: FEDORA, RedHat, etc. Classification: 17.7 External routines: Numerical Recipes in C [1], ROOT [2] Nature of problem: Statistical-thermal model analyses of heavy-ion collision data require the calculation of both primordial particle densities and contributions from resonance decay. A set of thermal parameters (the number depending on the particular model imposed) and a set of thermalized particles, with their decays specified, is required as input to these models. The output is then a complete set of primordial thermal quantities for each particle, together with the contributions to the final particle yields from resonance decay. In many applications of

Outdoor comfort study in Rio de Janeiro: site-related context effects on reported thermal sensation

NASA Astrophysics Data System (ADS)

Krüger, E.; Drach, P.; Broede, P.

2017-03-01

Aimed at climate-responsive urban design for tropical areas, the paper attempts to answer the question whether the site-related context affects in some way the perceptual assessment of the microclimate by users of outdoor spaces. Our hypothesis was that visual cues resulting from urban design are important components of the outdoor thermal perception. Monitoring was carried out alongside the administration of standard comfort questionnaires throughout summer periods in 2012-2015 in pedestrian areas of downtown Rio de Janeiro (22° 54 10 S, 43° 12 27 W), Brazil. Campaigns took place at different points, pre-defined in respect of urban geometry attributes. For the measurements, a Davis Vantage Pro2 weather station was employed to which a gray globe thermometer was attached. Two thermal indices were used for assessing the overall meteorological conditions and comfort levels in the outdoor locations: physiological equivalent temperature (PET) and universal thermal climate index (UTCI). Our results suggest that thermal sensation in Rio depends to a large extent on the thermal environment as described by air temperature, PET, or UTCI, and that urban geometry (expressed by the sky-view factor (SVF)) may modify this relationship with increased building density associated to warmer sensation votes under moderate heat stress conditions. This relationship however reverses under strong heat stress with warmer sensations in less obstructed locations, and disappears completely under still higher heat stress, where meteorological conditions, and not the site's SVF, will drive thermal sensation.

Outdoor comfort study in Rio de Janeiro: site-related context effects on reported thermal sensation.

PubMed

Krüger, E; Drach, P; Broede, P

2017-03-01

Aimed at climate-responsive urban design for tropical areas, the paper attempts to answer the question whether the site-related context affects in some way the perceptual assessment of the microclimate by users of outdoor spaces. Our hypothesis was that visual cues resulting from urban design are important components of the outdoor thermal perception. Monitoring was carried out alongside the administration of standard comfort questionnaires throughout summer periods in 2012-2015 in pedestrian areas of downtown Rio de Janeiro (22° 54 10 S, 43° 12 27 W), Brazil. Campaigns took place at different points, pre-defined in respect of urban geometry attributes. For the measurements, a Davis Vantage Pro2 weather station was employed to which a gray globe thermometer was attached. Two thermal indices were used for assessing the overall meteorological conditions and comfort levels in the outdoor locations: physiological equivalent temperature (PET) and universal thermal climate index (UTCI). Our results suggest that thermal sensation in Rio depends to a large extent on the thermal environment as described by air temperature, PET, or UTCI, and that urban geometry (expressed by the sky-view factor (SVF)) may modify this relationship with increased building density associated to warmer sensation votes under moderate heat stress conditions. This relationship however reverses under strong heat stress with warmer sensations in less obstructed locations, and disappears completely under still higher heat stress, where meteorological conditions, and not the site's SVF, will drive thermal sensation.

The Production of FRW Universe and Decay to Particles in Multiverse

NASA Astrophysics Data System (ADS)

Ghaffary, Tooraj

2017-09-01

In this study, first, it will be shown that as the Hubble parameter, " H", increases the production cross section for closed and flat Universes increases rapidly at smaller values of " H" and becomes constant for higher values of " H". However in the case of open Universe, the production cross section has been encountered a singularity. Before this singularity, as the H parameter increases, the cross section increases, for smaller H, ( H < 2.5), exhibits a turn-over at moderate values of H, (2.5 < H < 3.5), decreases for larger amount of H After that and for a special value of H, the cross section has been encountered with a singularity. Although the cross section cannot be defined at this singularity but before and after this point, it is certainly equal to zero. After this singularity, the cross section increases rapidly, when H increases. It is shown that if the production cross section of Universe happens before this singularity, it can't achieve to higher values of Hubble parameter after singularity. More over if the production cross section of Universe situates after the singularity, it won't get access to values of Hubble parameter less than the singularity. After that the thermal distribution for particles inside the FRW Universes are obtained. It is found that a large amount of particles are produced near apparent horizon due to their variety in their energy and their probabilities. Finally, comparing the particle production cross sections for flat, closed and open Universes, it is concluded that as the value of k increases, the cross section decreases.

Thermal/vacuum vs. thermal atmospheric testing of space flight electronic assemblies

NASA Technical Reports Server (NTRS)

Gibbel, Mark

1990-01-01

For space flight hardware, the thermal vacuum environmental test is the best test of a system's flight worthiness. Substituting an atmospheric pressure thermal test for a thermal/vacuum test can effectively reduce piece part temperatures by 20 C or more, even for low power density designs. Similar reductions in test effectiveness can also result from improper assembly level T/V test boundary conditions. The net result of these changes may reduce the effective test temperatures to the point where there is zero or negative margin over the flight thermal environment.

Variable pressure thermal insulating jacket

DOEpatents

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

1994-09-20

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

THERMAL REMEDIATION

EPA Science Inventory

Thermal remediation is being proposed by Region I for remediation of the overburden soil and groundwater at the Solvent Recovery Services New England Superfund site. This presentation at the public meeting will acquaint area residents with thermal remediation. The two types of ...

The Impact of Greenspace on Thermal Comfort in a Residential Quarter of Beijing, China.

PubMed

Wu, Zhifeng; Kong, Fanhua; Wang, Yening; Sun, Ranhao; Chen, Liding

2016-12-08

With the process of urbanization, a large number of residential quarters, which is the main dwelling form in the urban area of Beijing, have been developed in last three decades to accommodate the rising population. In the context of intensification of urban heat island (UHI), the potential degradation of the thermal environment of residential quarters can give rise to a variety of problems affecting inhabitants' health. This paper reports the results of a numerical study of the thermal conditions of a residential quarter on a typical summertime day under four greening modification scenarios, characterized by different leaf area density (LAD) profiles. The modelling results demonstrated that vegetation could evidently reduce near-surface air temperature, with the combination of grass and mature trees achieving as much as 1.5 °C of air temperature decrease compared with the non-green scenario. Vegetation can also lead to smaller air temperature fluctuations, which contribute to a more stable microclimate. The Universal Thermal Climate Index (UTCI) was then calculated to represent the variation of thermal environment of the study area. While grass is helpful in improving outdoor thermal comfort, trees are more effective in reducing the duration and expansion of suffering from severe heat stress. The results of this study showed that proper maintenance of vegetation, especially trees, is significant to improving the outdoor thermal environment in the summer season. In consideration of the deficiency of the current code in the management of greenspace in residential areas, we hope the results reported here will help promote the improvement of the code and related regulations for greenspace management.

Thermal neutron fluence in a treatment room with a Varian linear accelerator at a medical university hospital

NASA Astrophysics Data System (ADS)

Liu, Wen-Shan; Changlai, Sheng-Pin; Pan, Lung-Kwang; Tseng, Hsien-Chun; Chen, Chien-Yi

2011-09-01

The indium foil activation technique has been employed to measure thermal neutron fluences ( Φth) among various locations in the treatment room with a 20×20 cm 2 field size and a 15 and 10 MV X-ray beam. Spatial Φth are visualized using colored three-dimensional graphical representations; intensities are up to (1.97±0.13)×10 5 and (1.46±0.13)×10 4 n cm -2/Gy-X at isocenter, respectively. The Φth is found to increase with the X-ray energy of the LINAC and decreases as it moves away from the beam center. However, thermal neutron exposure is not assessed in routine dosimetry planning and radiation assessment of patients since neutron dose contributes <1% of the given therapy dose. However, unlike the accelerated beam limited within the gantry window, photoneutrons are widely spread in the treatment room. Distributions of Φth were measured in water phantom irradiated with 15 MV X-ray beams. The shielding effect of the maze was also evaluated. The experimentally estimated Φth along the maze distance was fitted explicate and the tenth-value layer (TVL) was calculated and discussed. Use of a 10 cm-thick polyethylene door placed at the maze was suitable for radiation shielding.

Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Gerrish, Harold P., Jr.

2003-01-01

This paper presents viewgraphs on Solar Thermal Propulsion (STP). Some of the topics include: 1) Ways to use Solar Energy for Propulsion; 2) Solar (fusion) Energy; 3) Operation in Orbit; 4) Propulsion Concepts; 5) Critical Equations; 6) Power Efficiency; 7) Major STP Projects; 8) Types of STP Engines; 9) Solar Thermal Propulsion Direct Gain Assembly; 10) Specific Impulse; 11) Thrust; 12) Temperature Distribution; 13) Pressure Loss; 14) Transient Startup; 15) Axial Heat Input; 16) Direct Gain Engine Design; 17) Direct Gain Engine Fabrication; 18) Solar Thermal Propulsion Direct Gain Components; 19) Solar Thermal Test Facility; and 20) Checkout Results.

Natural selection on thermal performance in a novel thermal environment

PubMed Central

Logan, Michael L.; Cox, Robert M.; Calsbeek, Ryan

2014-01-01

Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. PMID:25225361

Natural selection on thermal performance in a novel thermal environment.

PubMed

Logan, Michael L; Cox, Robert M; Calsbeek, Ryan

2014-09-30

Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming.

Influence of the Thermal Conductivity of Thermally Conductive Plastics on the Thermal Distribution of an Light-Emitting Diode Headlight for Vehicles.

PubMed

Lee, Dong Kyu; Lee, Jae Min; Cho, Moon Uk; Park, Hyun Jung; Cha, Yu-Jung; Kim, Hyeong Jin; Kwak, Joon Seop

2018-09-01

This paper investigates the thermal distribution of an LED headlight for vehicles based on the thermal conductivity of thermally conductive plastics (TCP). In general, heat dissipation structures used for LED headlights are made from metallic materials. However, headlight structures made from TCP have not been investigated. The headlights made from TCP having a various thermal conductivity were fabricated by injection molding with and without a metal plate insert. The temperature characteristics were compared and analyzed using thermal simulations and measurement. The inserted metal in TCP greatly reduced the temperature at solder point, indicating that the fast heat dissipation from the high power LED package to TCP though the inserted metal is essential. The measured temperature at solder points decreased as the thermal conductivity of TCP increased, which is well matched to the simulation results. The measured temperature at the solder point was lower than 150 °C when the thermal conductivity of the TCP was 10 W/mK.

Thermal insulation and body temperature wearing a thermal swimsuit during water immersion.

PubMed

Wakabayashi, Hitoshi; Hanai, Atsuko; Yokoyama, Shintaro; Nomura, Takeo

2006-09-01

This study evaluated the effects of a thermal swimsuit on body temperatures, thermoregulatory responses and thermal insulation during 60 min water immersion at rest. Ten healthy male subjects wearing either thermal swimsuits or normal swimsuits were immersed in water (26 degrees C or 29 degrees C). Esophageal temperature, skin temperatures and oxygen consumption were measured during the experiments. Metabolic heat production was calculated from oxygen consumption. Heat loss from skin to the water was calculated from the metabolic heat production and the change in mean body temperature during water immersion. Total insulation and tissue insulation were estimated by dividing the temperature difference between the esophagus and the water or the esophagus and the skin with heat loss from the skin. Esophageal temperature with a thermal swimsuit was higher than that with a normal swimsuit at the end of immersion in both water temperature conditions (p<0.05). Oxygen consumption, metabolic heat production and heat loss from the skin were less with the thermal swimsuit than with a normal swimsuit in both water temperatures (p<0.05). Total insulation with the thermal swimsuit was higher than that with a normal swimsuit due to insulation of the suit at both water temperatures (p<0.05). Tissue insulation was similar in all four conditions, but significantly higher with the thermal swimsuit in both water temperature conditions (p<0.05), perhaps due to of the attenuation of shivering during immersion with a thermal swimsuit. A thermal swimsuit can increase total insulation and reduce heat loss from the skin. Therefore, subjects with thermal swimsuits can maintain higher body temperatures than with a normal swimsuit and reduce shivering thermo-genesis.

Solar thermal aircraft

DOEpatents

Bennett, Charles L.

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.

Thermal comfort following immersion.

PubMed

Guéritée, Julien; Redortier, Bernard; House, James R; Tipton, Michael J

2015-02-01

Unlike thermal comfort in air, little research has been undertaken exploring thermal comfort around water sports. We investigated the impact of swimming and cooling in air after swimming on thermal comfort. After 10 min of swimming-and-resting cycles in 28°C water, volunteers wearing two types of garments or in swim briefs, faced winds in 24°C air, at rest or when stepping. Thermal comfort was significantly higher during swimming than resting. Post-immersion, following maximum discomfort, in 45 of 65 tests thermal comfort improved although mean skin temperature was still cooling (0.26 [SD 0.19] °C·min(-1) - max was 0.89°C·min(-1)). When thermal comfort was re-established mean skin temperature was lower than at maximal discomfort in 39 of 54 tests (0.81 [SD 0.58] °C - max difference was 2.68°C). The reduction in thermal discomfort in this scenario could be due to the adaptation of thermoreceptors, or to reductions in cooling rates to levels where discomfort was less stimulated. The relief from the recent discomfort may explain why, later, thermal comfort returned to initial levels in spite of poorer thermal profiles. Copyright © 2014 Elsevier Inc. All rights reserved.

Applications of high thermal conductivity composites to electronics and spacecraft thermal design

NASA Technical Reports Server (NTRS)

Sharp, G. Richard; Loftin, Timothy A.

1990-01-01

Recently, high thermal conductivity continuous graphite fiber reinforced metal matrix composites (MMC's) have become available that can save much weight over present methods of heat conduction. These materials have two or three times higher thermal conductivity in the fiber direction than the pure metals when compared on a thermal conductivity to weight basis. Use of these materials for heat conduction purposes can result in weight savings of from 50 to 70 percent over structural aluminum. Another significant advantage is that these materials can be used without the plumbing and testing complexities that accompany the use of liquid heat pipes. A spinoff of this research was the development of other MMC's as electronic device heat sinks. These use particulates rather than fibers and are formulated to match the coefficient of thermal expansion of electronic substrates in order to alleviate thermally induced stresses. The development of both types of these materials as viable weight saving substitutes for traditional methods of thermal control for electronics packaging and also for spacecraft thermal control applications are the subject of this report.

Thermal conductivity and thermal rectification in graphene nanoribbons: a molecular dynamics study.

PubMed

Hu, Jiuning; Ruan, Xiulin; Chen, Yong P

2009-07-01

We have used molecular dynamics to calculate the thermal conductivity of symmetric and asymmetric graphene nanoribbons (GNRs) of several nanometers in size (up to approximately 4 nm wide and approximately 10 nm long). For symmetric nanoribbons, the calculated thermal conductivity (e.g., approximately 2000 W/m-K at 400 K for a 1.5 nm x 5.7 nm zigzag GNR) is on the similar order of magnitude of the experimentally measured value for graphene. We have investigated the effects of edge chirality and found that nanoribbons with zigzag edges have appreciably larger thermal conductivity than nanoribbons with armchair edges. For asymmetric nanoribbons, we have found significant thermal rectification. Among various triangularly shaped GNRs we investigated, the GNR with armchair bottom edge and a vertex angle of 30 degrees gives the maximal thermal rectification. We also studied the effect of defects and found that vacancies and edge roughness in the nanoribbons can significantly decrease the thermal conductivity. However, substantial thermal rectification is observed even in the presence of edge roughness.

Thermal Vacuum Facility for Testing Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Knutson, Jeffrey R.; Sikora, Joseph G.

2002-01-01

A thermal vacuum facility for testing launch vehicle thermal protection systems by subjecting them to transient thermal conditions simulating re-entry aerodynamic heating is described. Re-entry heating is simulated by controlling the test specimen surface temperature and the environmental pressure in the chamber. Design requirements for simulating re-entry conditions are briefly described. A description of the thermal vacuum facility, the quartz lamp array and the control system is provided. The facility was evaluated by subjecting an 18 by 36 in. Inconel honeycomb panel to a typical re-entry pressure and surface temperature profile. For most of the test duration, the average difference between the measured and desired pressures was 1.6% of reading with a standard deviation of +/- 7.4%, while the average difference between measured and desired temperatures was 7.6% of reading with a standard deviation of +/- 6.5%. The temperature non-uniformity across the panel was 12% during the initial heating phase (t less than 500 sec.), and less than 2% during the remainder of the test.

Thermal conductivity and thermal expansion of graphite fiber-reinforced copper matrix composites

NASA Technical Reports Server (NTRS)

Ellis, David L.; Mcdanels, David L.

1993-01-01

The high specific conductivity of graphite fiber/copper matrix (Gr/Cu) composites offers great potential for high heat flux structures operating at elevated temperatures. To determine the feasibility of applying Gr/Cu composites to high heat flux structures, composite plates were fabricated using unidirectional and cross-plied pitch-based P100 graphite fibers in a pure copper matrix. Thermal conductivity of the composites was measured from room temperature to 1073 K, and thermal expansion was measured from room temperature to 1050 K. The longitudinal thermal conductivity, parallel to the fiber direction, was comparable to pure copper. The transverse thermal conductivity, normal to the fiber direction, was less than that of pure copper and decreased with increasing fiber content. The longitudinal thermal expansion decreased with increasing fiber content. The transverse thermal expansion was greater than pure copper and nearly independent of fiber content.

New Openings in University-Industry Cooperation: Aalto University as the Forerunner of European University Reform

ERIC Educational Resources Information Center

Markkula, Markku; Lappalainen, Pia

2009-01-01

The Innovation University (IU)--to be called the Aalto University after Alvav Aalto, a famous Finnish architect and MIT professor--is a new university which will be created through a merger of three existing universities: the Helsinki University of Technology (TKK), the Helsinki School of Economics (HSE) and the University of Art and Design…

MeProRisk - Acquisition and Prediction of thermal and hydraulic properties

NASA Astrophysics Data System (ADS)

Arnold, J.; Mottaghy, D.; Pechnig, R.

2009-04-01

MeProRisk is a joint project of five university institutes at RWTH Aachen University, Free University Berlin, and Kiel University. Two partners, namely Geophysica Beratunggesellschaft mbH (Aachen) and RWE Dea AG (Hamburg) present the industrial side. It is funded by the German Ministry of Education and Science (BMBF). The MeProRisk project aims to improve strategies to reduce the risk for planning geothermal power plants. Within our subproject we estimate geothermal relevant parameters in the laboratory and in the borehole scale. This basis data will be integrated with hydraulic and seismic experiments to provide a 3D reservoir model. Hitherto we focussed on two different type locations in Germany. These are (1) the crystalline basement in South Germany and (2) the Rotliegend formation and volcanic rocks in the Northern German Sedimentary Basin. In the case of the crystalline basement an extensive dataset could be composed from the 9 km deep KTB borehole including logging, core and cutting data. The whole data could be interpreted with respect to lithology, structure and alteration of the formation which mainly consists of alternating sequences of gneiss and metabasite. For the different rock types the data was analyzed statistically to provide specific values for geothermal key parameters. Important key parameters are for example: p-wave velocity, density, thermal conductivity, permeability and porosity. For the second type location we used logging data recovered within one borehole (> 5 km deep) which was drilled in the so called Voelkersen gas field. The data was supplied by the RWE DEA company. The formation comprises volcanic rocks and sandstones. On corresponding cores we measured p-wave velocity, thermal conductivity, density and porosity in the laboratory. In the same way as for type location (1) the complete data set was analyzed statistically to derive specific values which are relevant for the geothermal reservoir model. Finally this study will end up in

Studying the Physical Basis of Global Warming: Thermal Effects of the Interaction between Radiation and Matter and Greenhouse Effect

ERIC Educational Resources Information Center

Besson, Ugo; De Ambrosis, Anna; Mascheretti, Paolo

2010-01-01

We present a teaching module dealing with the thermal effects of interaction between radiation and matter, the infrared emission of bodies and the greenhouse effect devoted to university level and teacher education. The module stresses the dependence of the optical properties of materials (transparency, absorptivity and emissivity) on radiation…

The relationship between bioclimatic thermal stress and subjective thermal sensation in pedestrian spaces

NASA Astrophysics Data System (ADS)

Pearlmutter, David; Jiao, Dixin; Garb, Yaakov

2014-12-01

Outdoor thermal comfort has important implications for urban planning and energy consumption in the built environment. To better understand the relation of subjective thermal experience to bioclimatic thermal stress in such contexts, this study compares micrometeorological and perceptual data from urban spaces in the hot-arid Negev region of Israel. Pedestrians reported on their thermal sensation in these spaces, whereas radiation and convection-related data were used to compute the Index of Thermal Stress (ITS) and physiologically equivalent temperature (PET). The former is a straightforward characterization of energy exchanges between the human body and its surroundings, without any conversion to an "equivalent temperature." Although the relation of ITS to subjective thermal sensation has been analyzed in the past under controlled indoor conditions, this paper offers the first analysis of this relation in an outdoor setting. ITS alone can account for nearly 60 % of the variance in pedestrians' thermal sensation under outdoor conditions, somewhat more than PET. A series of regressions with individual contextual variables and ITS identified those factors which accounted for additional variance in thermal sensation, whereas multivariate analyses indicated the considerable predictive power ( R-square = 0.74) of models including multiple contextual variables in addition to ITS. Our findings indicate that pedestrians experiencing variable outdoor conditions have a greater tolerance for incremental changes in thermal stress than has been shown previously under controlled indoor conditions, with a tapering of responses at high values of ITS. However, the thresholds of ITS corresponding to thermal "neutrality" and thermal "acceptability" are quite consistent regardless of context.

The relationship between bioclimatic thermal stress and subjective thermal sensation in pedestrian spaces.

PubMed

Pearlmutter, David; Jiao, Dixin; Garb, Yaakov

2014-12-01

Outdoor thermal comfort has important implications for urban planning and energy consumption in the built environment. To better understand the relation of subjective thermal experience to bioclimatic thermal stress in such contexts, this study compares micrometeorological and perceptual data from urban spaces in the hot-arid Negev region of Israel. Pedestrians reported on their thermal sensation in these spaces, whereas radiation and convection-related data were used to compute the Index of Thermal Stress (ITS) and physiologically equivalent temperature (PET). The former is a straightforward characterization of energy exchanges between the human body and its surroundings, without any conversion to an "equivalent temperature." Although the relation of ITS to subjective thermal sensation has been analyzed in the past under controlled indoor conditions, this paper offers the first analysis of this relation in an outdoor setting. ITS alone can account for nearly 60 % of the variance in pedestrians' thermal sensation under outdoor conditions, somewhat more than PET. A series of regressions with individual contextual variables and ITS identified those factors which accounted for additional variance in thermal sensation, whereas multivariate analyses indicated the considerable predictive power (R-square = 0.74) of models including multiple contextual variables in addition to ITS. Our findings indicate that pedestrians experiencing variable outdoor conditions have a greater tolerance for incremental changes in thermal stress than has been shown previously under controlled indoor conditions, with a tapering of responses at high values of ITS. However, the thresholds of ITS corresponding to thermal "neutrality" and thermal "acceptability" are quite consistent regardless of context.

Multilayer thermal barrier coating systems

DOEpatents

Vance, Steven J.; Goedjen, John G.; Sabol, Stephen M.; Sloan, Kelly M.

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.

Equilibrium statistical-thermal models in high-energy physics

NASA Astrophysics Data System (ADS)

Tawfik, Abdel Nasser

2014-05-01

We review some recent highlights from the applications of statistical-thermal models to different experimental measurements and lattice QCD thermodynamics that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical-thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948, an almost complete recipe for the statistical-thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it, the simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analyzed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-particle systems can be studied with the help of statistical-thermal methods. The analysis of yield multiplicities in high-energy collisions gives an overwhelming evidence for the chemical equilibrium in the final state. The strange particles might be an exception, as they are suppressed at lower beam energies. However, their relative yields fulfill statistical equilibrium, as well. We review the equilibrium statistical-thermal models for particle production, fluctuations and collective flow in heavy-ion experiments. We also review their reproduction of the lattice QCD thermodynamics at vanishing and finite chemical potential. During the last decade, five conditions have been suggested to describe the universal behavior of the chemical freeze-out parameters. The higher order moments of multiplicity have been discussed. They offer deep insights about particle production and to critical fluctuations. Therefore, we use them to describe the freeze-out parameters

High-Rise Buildings versus Outdoor Thermal Environment in Chongqing

PubMed Central

Lu, Jun; Chen, Jin-hua; Tang, Ying; Feng, Yuan; Wang, Jin-sha

2007-01-01

This paper gives a brief description of the over quick urbanization since Chongqing, one of the biggest cities in China, has been a municipality directly under the Central Government in 1997, excessive development and exceeding increase of high-rise buildings because of its special geographical position which finally leads to the worsening of the urban outdoor thermal environment. Then, this paper makes a bright balance to the field measurement and simulated results of the wind speed field, temperature field of one multifunctional high-rise building in Chongqing university located in the city center, and the contrasted results validate the correctness of CFD in the outdoor thermal environmental simulation, expose the disadvantages of high-rise buildings on the aspects of blocking the wind field, decreasing wind speed which results in accumulation of the air-conditioning heat revolving around and periscian region where sunshine can not rip into. Finally, in order to improve the urban outdoor thermal environment near the high-rise buildings especially for the angle of natural ventilation, this paper simulates the wind environment in different architectural compositions and architectural layouts by CFD, and the simulated results show that freestyle and tower buildings which can guarantee the wind speed and take the air-conditioning heat away are much suitable and reasonable for the special Chongqing geography. These conclusions can also be used as a reference in other mountain cities, especially for the one with a great number of populations. PMID:28903222

Determination of Thermal State of Charge in Solar Heat Receivers

NASA Technical Reports Server (NTRS)

Glakpe, E. K.; Cannon, J. N.; Hall, C. A., III; Grimmett, I. W.

1996-01-01

The research project at Howard University seeks to develop analytical and numerical capabilities to study heat transfer and fluid flow characteristics, and the prediction of the performance of solar heat receivers for space applications. Specifically, the study seeks to elucidate the effects of internal and external thermal radiation, geometrical and applicable dimensionless parameters on the overall heat transfer in space solar heat receivers. Over the last year, a procedure for the characterization of the state-of-charge (SOC) in solar heat receivers for space applications has been developed. By identifying the various factors that affect the SOC, a dimensional analysis is performed resulting in a number of dimensionless groups of parameters. Although not accomplished during the first phase of the research, data generated from a thermal simulation program can be used to determine values of the dimensionless parameters and the state-of-charge and thereby obtain a correlation for the SOC. The simulation program selected for the purpose is HOTTube, a thermal numerical computer code based on a transient time-explicit, axisymmetric model of the total solar heat receiver. Simulation results obtained with the computer program are presented the minimum and maximum insolation orbits. In the absence of any validation of the code with experimental data, results from HOTTube appear reasonable qualitatively in representing the physical situations modeled.

Thermal conductivity and thermal diffusivity of methane hydrate formed from compacted granular ice

NASA Astrophysics Data System (ADS)

Zhao, Jie; Sun, Shicai; Liu, Changling; Meng, Qingguo

2018-05-01

Thermal conductivity and thermal diffusivity of pure methane hydrate samples, formed from compacted granular ice (0-75 μm), and were measured simultaneously by the transient plane source (TPS) technique. The temperature dependence was measured between 263.15 and 283.05 K, and the gas-phase pressure dependence was measured between 2 and 10 MPa. It is revealed that the thermal conductivity of pure methane hydrate exhibits a positive trend with temperature and increases from 0.4877 to 0.5467 W·m-1·K-1. The thermal diffusivity of methane hydrate has inverse dependence on temperature and the values in the temperature range from 0.2940 to 0.3754 mm2·s-1, which is more than twice that of water. The experimental results show that the effects of gas-phase pressure on the thermal conductivity and thermal diffusivity are very small. Thermal conductivity of methane hydrate is found to have weakly positive gas-phase pressure dependence, whereas the thermal diffusivity has slightly negative trend with gas-phase pressure.

Thermal-to-visible transducer (TVT) for thermal-IR imaging

NASA Astrophysics Data System (ADS)

Flusberg, Allen; Swartz, Stephen; Huff, Michael; Gross, Steven

2008-04-01

We have been developing a novel thermal-to-visible transducer (TVT), an uncooled thermal-IR imager that is based on a Fabry-Perot Interferometer (FPI). The FPI-based IR imager can convert a thermal-IR image to a video electronic image. IR radiation that is emitted by an object in the scene is imaged onto an IR-absorbing material that is located within an FPI. Temperature variations generated by the spatial variations in the IR image intensity cause variations in optical thickness, modulating the reflectivity seen by a probe laser beam. The reflected probe is imaged onto a visible array, producing a visible image of the IR scene. This technology can provide low-cost IR cameras with excellent sensitivity, low power consumption, and the potential for self-registered fusion of thermal-IR and visible images. We will describe characteristics of requisite pixelated arrays that we have fabricated.

Ceramic thermal barrier coating for rapid thermal cycling applications

DOEpatents

Scharman, Alan J.; Yonushonis, Thomas M.

1994-01-01

A thermal barrier coating for metal articles subjected to rapid thermal cycling includes a metallic bond coat deposited on the metal article, at least one MCrAlY/ceramic layer deposited on the bond coat, and a ceramic top layer deposited on the MCrAlY/ceramic layer. The M in the MCrAlY material is Fe, Ni, Co, or a mixture of Ni and Co. The ceramic in the MCrAlY/ceramic layer is mullite or Al.sub.2 O.sub.3. The ceramic top layer includes a ceramic with a coefficient of thermal expansion less than about 5.4.times.10.sup.-6 .degree.C.sup.-1 and a thermal conductivity between about 1 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1 and about 1.7 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1.

The influence of thermal discomfort on the attention index of teenagers: an experimental evaluation

NASA Astrophysics Data System (ADS)

Mazon, Jordi

2014-07-01

In order to measure the effect on the attention of teenagers of thermal discomfort due to high temperature and humidity, two experiments were conducted in two different indoor conditions of temperature and humidity in non-air-conditioned classrooms. The participants were a heterogeneous group of 117 teenagers, aged 12 to 18 years, and the experiments reproduced the actual conditions of teaching in a classroom in the Mediterranean climate. In order to measure the attention index, a standard Toulouse-Pieron psychological test was performed on the 117 teenagers in these two conditions, and the Predicted Mean Vote (PMV), the physiologically Equivalent Temperature (PET), the Standard effective Temperature (SET*) and the Universal Thermal Climate Index (UTCI) indices were calculated to estimate the grade of discomfort using the RayMan Pro model. Conditions of greater discomfort decreased the attention index in the whole group, especially in those aged 12-14, among whom the attention index dropped by around 45 % when compared to comfortable conditions. However, teenage attention at ages 17 and 18 shows little variation in discomfort in respect to thermally comfortable conditions. In addition, the attention index for boys and girls shows the same variation in discomfort conditions. However, girls have a slightly higher attention index than boys in discomfort and thermal comfort experiments.

Single-beam thermal lens measurement of thermal diffusivity of engine coolants

NASA Astrophysics Data System (ADS)

George, Nibu A.; Thomas, Nibu B.; Chacko, Kavya; T, Neethu V.; Hussain Moidu, Haroon; Piyush, K.; David, Nitheesh M.

2015-04-01

Automobile engine coolant liquids are commonly used for efficient heat transfer from the engine to the surroundings. In this work we have investigated the thermal diffusivity of various commonly available engine coolants in Indian automobile market. We have used single beam laser induced thermal lens technique for the measurements. Engine coolants are generally available in concentrated solution form and are recommended to use at specified dilution. We have investigated the samples in the entire recommended concentration range for the use in radiators. While some of the brands show an enhanced thermal diffusivity compared to pure water, others show slight decrease in thermal diffusivity.

Low-cycle thermal fatigue

NASA Technical Reports Server (NTRS)

Halford, G. R.

1986-01-01

A state-of-the-art review is presented of the field of thermal fatigue. Following a brief historical review, the concept is developed that thermal fatigue can be viewed as processes of unbalanced deformation and cracking. The unbalances refer to dissimilar mechanisms occurring in opposing halves of thermal fatigue loading and unloading cycles. Extensive data summaries are presented and results are interpreted in terms of the unbalanced processes involved. Both crack initiation and crack propagation results are summarized. Testing techniques are reviewed, and considerable discussion is given to a technique for thermal fatigue simulation, known as the bithermal fatigue test. Attention is given to the use of isothermal life prediction methods for the prediction of thermal fatigue lives. Shortcomings of isothermally-based life prediction methods are pointed out. Several examples of analyses and thermal fatigue life predictions of high technology structural components are presented. Finally, numerous dos and don'ts relative to design against thermal fatigue are presented.

The First Modern University: The University of Birmingham

ERIC Educational Resources Information Center

Arthur, James

2017-01-01

The University of Birmingham was planned, advanced and established with both national and German models of a University in mind. Civic reasons for the planning of the University need to be viewed within a broader motivational context. Even with a strong sense of civic place, the University was conceived as a modern University with multiple…

Thermal insulation materials for inside applications: Hygric and thermal properties

NASA Astrophysics Data System (ADS)

Jerman, Miloš; Černý, Robert

2017-11-01

Two thermal insulation materials suitable for the application on the interior side of historical building envelopes, namely calcium silicate and polyurethane-based foam are studied. Moisture diffusivity and thermal conductivity of both materials, as fundamental moisture and heat transport parameters, are measured in a dependence on moisture content. The measured data will be used as input parameters in computer simulation studies which will provide moisture and temperature fields necessary for an appropriate design of interior thermal insulation systems.

Metal–Organic–Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances

DOE PAGES

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui; ...

2017-02-27

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Here in this paper, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix -- which are prepared by chemisorption-coupledmore » electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m.K), which are very high considering their relatively low elastic modulus values on the order of 21.2 to 28.5 GPa. The synergistic combination of these properties lead to the ultra-low total thermal resistivity values in the range of 0.38 to 0.56 mm 2.K/W for a typical bondline thickness of 30-50 um, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally-induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.« less

Metal–Organic–Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Here in this paper, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix -- which are prepared by chemisorption-coupledmore » electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m.K), which are very high considering their relatively low elastic modulus values on the order of 21.2 to 28.5 GPa. The synergistic combination of these properties lead to the ultra-low total thermal resistivity values in the range of 0.38 to 0.56 mm 2.K/W for a typical bondline thickness of 30-50 um, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally-induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.« less

Metal-Organic-Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances.

PubMed

Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui; King, Charles; Catalano, Massimo; Oh, Jun Kyun; Talib, Ansam J; Scholar, Ethan A; Verkhoturov, Stanislav V; Cagin, Tahir; Sokolov, Alexei V; Kim, Moon J; Matin, Kaiser; Narumanchi, Sreekant; Akbulut, Mustafa

2017-03-22

As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Herein, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix-which are prepared by the chemisorption-coupled electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m K), which are very high considering their relatively low elastic modulus values on the order of 21.2-28.5 GPa. The synergistic combination of these properties led to the ultralow total thermal resistivity values in the range of 0.38-0.56 mm 2 K/W for a typical bond-line thickness of 30-50 μm, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.

Building Thermal Models

NASA Technical Reports Server (NTRS)

Peabody, Hume L.

2017-01-01

This presentation is meant to be an overview of the model building process It is based on typical techniques (Monte Carlo Ray Tracing for radiation exchange, Lumped Parameter, Finite Difference for thermal solution) used by the aerospace industry This is not intended to be a "How to Use ThermalDesktop" course. It is intended to be a "How to Build Thermal Models" course and the techniques will be demonstrated using the capabilities of ThermalDesktop (TD). Other codes may or may not have similar capabilities. The General Model Building Process can be broken into four top level steps: 1. Build Model; 2. Check Model; 3. Execute Model; 4. Verify Results.

Characterization of Textiles Used in Chefs' Uniforms for Protection Against Thermal Hazards Encountered in the Kitchen Environment.

PubMed

Zhang, Han; McQueen, Rachel H; Batcheller, Jane C; Ehnes, Briana L; Paskaluk, Stephen A

2015-10-01

Within the kitchen the potential for burn injuries arising from contact with hot surfaces, flames, hot liquid, and steam hazards is high. The chef's uniform can potentially offer some protection against such burns by providing a protective barrier between the skin and the thermal hazard, although the extent to which can provide some protection is unknown. The purpose of this study was to examine whether fabrics used in chefs' uniforms were able to provide some protection against thermal hazards encountered in the kitchen. Fabrics from chefs' jackets and aprons were selected. Flammability of single- and multiple-layered fabrics was measured. Effect of jacket type, apron and number of layers on hot surface, hot water, and steam exposure was also measured. Findings showed that all of the jacket and apron fabrics rapidly ignited when exposed to a flame. Thermal protection against hot surfaces increased as layers increased due to more insulation. Protection against steam and hot water improved with an impermeable apron in the system. For wet thermal hazards increasing the number of permeable layers can decrease the level of protection due to stored thermal energy. As the hands and arms are most at risk of burn injury increased insulation and water-impermeable barrier in the sleeves would improve thermal protection with minimal compromise to overall thermal comfort. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

The median density of the Universe

NASA Astrophysics Data System (ADS)

Stücker, Jens; Busch, Philipp; White, Simon D. M.

2018-03-01

Despite the fact that the mean matter density of the universe has been measured to an accuracy of a few percent within the standard ΛCDM paradigm, its median density is not known even to order of magnitude. Typical points lie in low-density regions and are not part of a collapsed structure of any scale. Locally, the dark matter distribution is then simply a stretched version of that in the early universe. In this single-stream regime, the distribution of unsmoothed density is sensitive to the initial power spectrum on all scales, in particular on very small scales, and hence to the nature of the dark matter. It cannot be estimated reliably using conventional cosmological simulations because of the enormous dynamic range involved, but a suitable excursion set procedure can be used instead. For the Planck cosmological parameters, a 100 GeV WIMP, corresponding to a free-streaming mass ˜10-6M⊙, results in a median density of ˜4 × 10-3 in units of the mean density, whereas a 10 μeV axion with free-streaming mass ˜10-12M⊙ gives ˜3 × 10-3, and Warm Dark Matter with a (thermal relic) mass of 1 keV gives ˜8 × 10-2. In CDM (but not in WDM) universes, single-stream regions are predicted to be topologically isolated by the excursion set formalism. A test by direct N-Body simulations seems to confirm this prediction, although it is still subject to finite size and resolution effects. Unfortunately, it is unlikely that any of these properties is observable and so suitable for constraining the properties of dark matter.

Studying the physical basis of global warming: thermal effects of the interaction between radiation and matter and greenhouse effect

NASA Astrophysics Data System (ADS)

Besson, Ugo; De Ambrosis, Anna; Mascheretti, Paolo

2010-03-01

We present a teaching module dealing with the thermal effects of interaction between radiation and matter, the infrared emission of bodies and the greenhouse effect devoted to university level and teacher education. The module stresses the dependence of the optical properties of materials (transparency, absorptivity and emissivity) on radiation frequency, as a result of interaction between matter and radiation. Multiple experiences are suggested to favour a progressive construction of knowledge on the physical aspects necessary to understand the greenhouse effect and global warming. Some results obtained with university students are briefly reported.

Advanced Thermal Batteries.

DTIC Science & Technology

1981-06-01

ADVANCED THERMAL BATTERIES NATIONAL UNION ELECTRIC CORPORATION ADVANCE SCIENCE DIVISION 1201 E. BELL STREET BLXXMINGTON, ILLINOIS 61701 JUNE 1981...December 1978 in: " Advanced Thermal Batteries " AFAPL-TR-78-114 Air Force Aero Propulsion Laboratory Air Force Wright Aeronautical Laboratories Air Force...March 1980 in: " Advanced Thermal Batteries " AFAPL-TR-80-2017 Air Force Aero Propulsion Laboratory Air Force Wright Aeronautical Laboratories Air Force

Thermally Activated Driver

NASA Technical Reports Server (NTRS)

Kinard, William H.; Murray, Robert C.; Walsh, Robert F.

1987-01-01

Space-qualified, precise, large-force, thermally activated driver (TAD) developed for use in space on astro-physics experiment to measure abundance of rare actinide-group elements in cosmic rays. Actinide cosmic rays detected using thermally activated driver as heart of event-thermometer (ET) system. Thermal expansion and contraction of silicone oil activates driver. Potential applications in fluid-control systems where precise valve controls are needed.

Thermal Management Coating As Thermal Protection System for Space Transportation System

NASA Technical Reports Server (NTRS)

Kaul, Raj; Stuckey, C. Irvin

2003-01-01

This paper presents viewgraphs on the development of a non-ablative thermal management coating used as the thermal protection system material for space shuttle rocket boosters and other launch vehicles. The topics include: 1) Coating Study; 2) Aerothermal Testing; 3) Preconditioning Environments; 4) Test Observations; 5) Lightning Strike Test Panel; 6) Test Panel After Impact Testing; 7) Thermal Testing; and 8) Mechanical Testing.

Influence of PCMs in thermal insulation on thermal behaviour of building envelopes

NASA Astrophysics Data System (ADS)

Dydek, K.; Furmański, P.; Łapka, P.

2016-09-01

A model of heat transfer through a wall consisting of a layer of concrete and PCM enhanced thermal insulation is considered. The model accounts for heat conduction in both layers, thermal radiation and heat absorption/release due to phase change in the insulation as well as time variation in the ambient temperature and insolation. Local thermal equilibrium between encapsulated PCM and light-weight thermal insulation was assumed. Radiation emission, absorption and scattering were also accounted for in the model. Comparison of different cases of heat flow through the building envelope was carried out. These cases included presence or absence of PCM and thermal radiation in the insulation, effect of emissivity of the PCM microcapsules as well as an effect of solar radiation or its lack on the ambient side of the envelope. Two ways of the PCM distribution in thermal insulation were also considered. The results of simulations were presented for conditions corresponding to the mean summer and winter seasons in Warsaw. It was found that thermal radiation plays an important role in heat transfer through thermal insulation layer of the wall while the presence of the PCM in it significantly contributes to damping of temperature fluctuations and a decrease in heat fluxes flowing into or lost by the interior of the building. The similar effect was observed for a decrease in emissivity of the microcapsules containing PCM.

Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

PubMed Central

Lu, Zhe; Myoung, Sang-Won; Jung, Yeon-Gil; Balakrishnan, Govindasamy; Lee, Jeongseung; Paik, Ungyu

2013-01-01

The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs) was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF) for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS) method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF) for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF) and low-pressure plasma spray (LPPS) methods showed a partial cracking (and/or delamination) and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50%) after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF. PMID:28811441

Measuring Volcanic Thermal Output

NASA Astrophysics Data System (ADS)

Reath, K.

2017-12-01

In most cases, volcanic eruptions are preceded by some form of unrest that can be used as an early warning sign of an impending eruption or provide insight into changing hazards during an eruption, contingent upon this unrest being properly monitored and understood. Many ground and satellite monitoring techniques have been developed to identify the varying types volcanic unrest, including seismic, degassing, deformation, and thermal measurements. High spatial resolution thermal infrared (TIR) remote sensing, such as the thermal images acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor, have proven particularly effective at identifying and tracking variations in thermal unrest in the form of volcanic thermal anomalies. However, the majority of ASTER thermal anomaly studies have focused on tracking the variations in the temperature of the hottest pixel above background in the anomaly. Whereas, this remains a valid method as it reveals valuable information about variations occurring at the main vent of a volcano, it does not incorporate the thermal output of the entire anomaly, which typically expands beyond one pixel due to the heating of the surrounding area. By developing a weighted area method that considers both the thermal anomaly area and temperature the total thermal output of an anomaly can be measured. It some case studies, such as the period before the 2016 Sabancaya eruption, both temperature and area increase before an eruptive event. Here, the weighted area methods demonstrates a clearer increase in thermal unrest than the traditional above temperature method. In other case studies, such as the thermal anomaly observed at Lascar volcano, the area of the anomaly remains relatively constant. This limits the variation in values between these two methods. However, by incorporating data from both of these methods, valuable interpretations can be made about the dynamics of the main vent where compared to the full

Thermal Change and the Dynamics of Multi-Host Parasite Life Cycles in Aquatic Ecosystems.

PubMed

Barber, Iain; Berkhout, Boris W; Ismail, Zalina

2016-10-01

Altered thermal regimes associated with climate change are impacting significantly on the physical, chemical, and biological characteristics of the Earth's natural ecosystems, with important implications for the biology of aquatic organisms. As well as impacting the biology of individual species, changing thermal regimes have the capacity to mediate ecological interactions between species, and the potential for climate change to impact host-parasite interactions in aquatic ecosystems is now well recognized. Predicting what will happen to the prevalence and intensity of infection of parasites with multiple hosts in their life cycles is especially challenging because the addition of each additional host dramatically increases the potential permutations of response. In this short review, we provide an overview of the diverse routes by which altered thermal regimes can impact the dynamics of multi-host parasite life cycles in aquatic ecosystems. In addition, we examine how experimentally amenable host-parasite systems are being used to determine the consequences of changing environmental temperatures for these different types of mechanism. Our overarching aim is to examine the potential of changing thermal regimes to alter not only the biology of hosts and parasites, but also the biology of interactions between hosts and parasites. We also hope to illustrate the complexity that is likely to be involved in making predictions about the dynamics of infection by multi-host parasites in thermally challenged aquatic ecosystems. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.

Theoretical analysis for scaling law of thermal blooming based on optical phase deference

NASA Astrophysics Data System (ADS)

Sun, Yunqiang; Huang, Zhilong; Ren, Zebin; Chen, Zhiqiang; Guo, Longde; Xi, Fengjie

2016-10-01

In order to explore the laser propagation influence of thermal blooming effect of pipe flow and to analysis the influencing factors, scaling law theoretical analysis of the thermal blooming effects in pipe flow are carry out in detail based on the optical path difference caused by thermal blooming effects in pipe flow. Firstly, by solving the energy coupling equation of laser beam propagation, the temperature of the flow is obtained, and then the optical path difference caused by the thermal blooming is deduced. Through the analysis of the influence of pipe size, flow field and laser parameters on the optical path difference, energy scaling parameters Ne=nTαLPR2/(ρɛCpπR02) and geometric scaling parameters Nc=νR2/(ɛL) of thermal blooming for the pipe flow are derived. Secondly, for the direct solution method, the energy coupled equations have analytic solutions only for the straight tube with Gauss beam. Considering the limitation of directly solving the coupled equations, the dimensionless analysis method is adopted, the analysis is also based on the change of optical path difference, same scaling parameters for the pipe flow thermal blooming are derived, which makes energy scaling parameters Ne and geometric scaling parameters Nc have good universality. The research results indicate that when the laser power and the laser beam diameter are changed, thermal blooming effects of the pipeline axial flow caused by optical path difference will not change, as long as you keep energy scaling parameters constant. When diameter or length of the pipe changes, just keep the geometric scaling parameters constant, the pipeline axial flow gas thermal blooming effects caused by optical path difference distribution will not change. That is to say, when the pipe size and laser parameters change, if keeping two scaling parameters with constant, the pipeline axial flow thermal blooming effects caused by the optical path difference will not change. Therefore, the energy scaling

Effects of thermal underwear on thermal and subjective responses in winter.

PubMed

Choi, Jeong-Wha; Lee, Joo-Young; Kim, So-Young

2003-01-01

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher

Thermal Comfort and Thermal Sensation During Exposure to Hot, Hot-Humid and Thermoneutral Environments

DTIC Science & Technology

1998-01-01

than COND 2(6 +/- 2 W) and COND 3 (11 +/- 5 W, p 0.05). The thermal comfort and thermal sensation assessments reflected the physiological responses...was related to thermal comfort (R2 = 0.94. This research provided evidence that skin wettedness predicted thermal comfort effectively in all...environments tested. The subjective assessment of thermal comfort discriminated between all environments and the heat index derived from the USARIEM

Handling of thermal paper: Implications for dermal exposure to bisphenol A and its alternatives