Dark matter relic abundance and light sterile neutrinos

Energy Technology Data Exchange (ETDEWEB)

Tang, Yi-Lei [Center for High Energy Physics,Peking University, Beijing 100871 (China); Zhu, Shou-hua [Center for High Energy Physics,Peking University, Beijing 100871 (China); Institute of Theoretical Physics & State Key Laboratory of Nuclear Physics and Technology,Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,Beijing 100871 (China)

2017-01-09

In this paper, we calculate the relic abundance of the dark matter particles when they can annihilate into sterile neutrinos with the mass ≲100 GeV in a simple model. Unlike the usual standard calculations, the sterile neutrino may fall out of the thermal equilibrium with the thermal bath before the dark matter freezes out. In such a case, if the Yukawa coupling y{sub N} between the Higgs and the sterile neutrino is small, this process gives rise to a larger Ω{sub DM}h{sup 2} so we need a larger coupling between the dark matter and the sterile neutrino for a correct relic abundance.

Relics in galaxy clusters at high radio frequencies

Science.gov (United States)

Kierdorf, M.; Beck, R.; Hoeft, M.; Klein, U.; van Weeren, R. J.; Forman, W. R.; Jones, C.

2017-04-01

fronts that are observed edge-on. The polarization degrees correspond to Mach numbers of >2.2. Polarized emission is also detected in the radio relics in ZwCl 0008+52 and, for the first time, in Abell 1612. The smaller sizes and lower degrees of polarizations of the latter relics indicate a weaker shock and/or an inclination between the relic and the sky plane. Abell 1612 shows a complex X-ray surface brightness distribution, indicating a recent major merger and supporting the classification of the radio emission as a radio relic. In our cluster sample, no wavelength-dependent Faraday depolarization is detected between 4.85 GHz and 8.35 GHz, except for one component of the Toothbrush relic. Faraday depolarization between 1.38 GHz and 8.35 GHz varies with distance from the center of the host cluster 1RXS 06+42, which can be explained by a decrease in electron density and/or in strength of a turbulent (or tangled) magnetic field. Faraday rotation measures show large-scale gradients along the relics, which cannot be explained by variations in the Milky Way foreground. Conclusions: Single-dish telescopes are ideal tools to confirm relic candidates and search for new relic candidates. Measurement of the wavelength-dependent depolarization along the Toothbrush relic shows that the electron density of the intra-cluster medium (ICM) and strength of the tangled magnetic field decrease with distance from the center of the foreground cluster. Large-scale regular fields appear to be present in intergalactic space around galaxy clusters. Based on observations with the 100-m telescope at Effelsberg, operated by the Max-Planck-Institut für Radioastronomie (MPIfR) on behalf of the Max-Planck-Gesellschaft.The reduced Stokes parameter images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/A18

Asymmetric thermal-relic dark matter. Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

International Nuclear Information System (INIS)

Baldes, Iason; Petraki, Kalliopi

2017-03-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

Energy Technology Data Exchange (ETDEWEB)

Baldes, Iason [DESY, Notkestraße 85, Hamburg, D-22607 Germany (Germany); Petraki, Kalliopi, E-mail: iason.baldes@desy.de, E-mail: kpetraki@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies (LPTHE), UMR 7589 CNRS and UPMC, 4 Place Jussieu, Paris, F-75252 France (France)

2017-09-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter. Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

Energy Technology Data Exchange (ETDEWEB)

Baldes, Iason [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Petraki, Kalliopi [Nationaal Instuut voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); UMR 7589 CNRS et UPMC, Paris (France). Laboratoire de Physique Theorique et Hautes Energies (LPTHE)

2017-03-15

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

International Nuclear Information System (INIS)

Baldes, Iason; Petraki, Kalliopi

2017-01-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Stochastic backgrounds of relic gravitons: a theoretical appraisal

CERN Document Server

Giovannini, Massimo

2010-01-01

Stochastic backgrounds or relic gravitons, if ever detected, will constitute a prima facie evidence of physical processes taking place during the earliest stages of the evolution of the plasma. The essentials of the stochastic backgrounds of relic gravitons are hereby introduced and reviewed. The pivotal observables customarily employed to infer the properties of the relic gravitons are discussed both in the framework of the $\\Lambda$CDM paradigm as well as in neighboring contexts. The complementarity between experiments measuring the polarization of the Cosmic Microwave Background (such as, for instance, WMAP, Capmap, Quad, Cbi, just to mention a few) and wide band interferometers (e.g. Virgo, Ligo, Geo, Tama) is emphasized. While the analysis of the microwave sky strongly constrains the low-frequency tail of the relic graviton spectrum, wide-band detectors are sensitive to much higher frequencies where the spectral energy density depends chiefly upon the (poorly known) rate of post-inflationary expansion.

Lensing substructure quantification in RXJ1131-1231: a 2 keV lower bound on dark matter thermal relic mass

Energy Technology Data Exchange (ETDEWEB)

Birrer, Simon; Amara, Adam; Refregier, Alexandre, E-mail: simon.birrer@phys.ethz.ch, E-mail: adam.amara@phys.ethz.ch, E-mail: alexandre.refregier@phys.ethz.ch [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich (Switzerland)

2017-05-01

We study the substructure content of the strong gravitational lens RXJ1131-1231 through a forward modelling approach that relies on generating an extensive suite of realistic simulations. We use a semi-analytic merger tree prescription that allows us to stochastically generate substructure populations whose properties depend on the dark matter particle mass. These synthetic halos are then used as lenses to produce realistic mock images that have the same features, e.g. luminous arcs, quasar positions, instrumental noise and PSF, as the data. We then analyse the data and the simulations in the same way with summary statistics that are sensitive to the signal being targeted and are able to constrain models of dark matter statistically using Approximate Bayesian Computing (ABC) techniques. (In this work, we focus on the thermal relic mass estimate and fix the semi-analytic descriptions of the substructure evolution based on recent literature.) We are able, based on the HST data for RXJ1131-1231, to rule out a warm dark matter thermal relic mass below 2 keV at the 2σ confidence level.

Stau relic density at the big-bang nucleosynthesis era in the coannihilation scenario and a solution to the Li7 problem

Science.gov (United States)

Jittoh, Toshifumi; Kohri, Kazunori; Koike, Masafumi; Sato, Joe; Shimomura, Takashi; Yamanaka, Masato

2010-12-01

We calculate the relic density of stau at the big-bang nucleosynthesis era in the coannihilation scenario of the minimal supersymmetric standard model. In this scenario, stau can be long lived and have significance in the remediation of light elements abundances. The freeze-out of stau is corroborated by solving the Boltzmann equation numerically, and the parameter dependence of the relic density is investigated. The possibility of solving the Li7 problem is examined by taking account into the long-lived stau. By adopting an observational value of Li7 in [J. Meléndez and I. Ramírez, Astrophys. J. 615, L33 (2004).ASJOAB0004-637X10.1086/425962], we get minimal supersymmetric standard model parameter space in which abundances of both dark matter and all of the light elements are reproduced in accordance with observations. We also address the influence of intergenerational mixing on our calculation.

From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter

Energy Technology Data Exchange (ETDEWEB)

Scopel, Stefano; Yu, Hyeonhye, E-mail: scopel@sogang.ac.kr, E-mail: skyh2yu@gmail.com [Department of Physics, Sogang University, Seoul (Korea, Republic of)

2017-04-01

We discuss strategies to make inferences on the thermal relic abundance of a Weakly Interacting Massive Particle (WIMP) when the same effective dimension-six operator that explains an experimental excess in direct detection is assumed to drive decoupling at freeze-out, and apply them to the explicit scenario of WIMP inelastic up-scattering with spin-dependent couplings to protons (proton-philic Spin-dependent Inelastic Dark Matter, pSIDM), a phenomenological set-up containing two Dark Matter (DM) particles χ{sub 1} and χ{sub 2} with masses m {sub χ}= m {sub χ{sub 1}} and m {sub χ{sub 2}}= m {sub χ}+δ that we have shown in a previous paper to explain the DAMA effect in compliance with the constraints from other detectors. We also update experimental constraints on pSIDM, extend the analysis to the most general spin-dependent momentum-dependent interactions allowed by non-relativistic Effective Field Theory (EFT), and consider for the WIMP velocity distribution in our Galaxy f ( v ) both a halo-independent approach and a standard Maxwellian. Under these conditions we find that the DAMA effect can be explained in terms of the particle χ{sub 1} in compliance with all the other constraints for all the analyzed EFT couplings and also for a Maxwellian f ( v ). As far as the relic abundance is concerned, we show that the problem of calculating it by using direct detection data to fix the model parameters is affected by a strong sensitivity on f ( v ) and by the degeneracy between the WIMP local density ρ{sub χ} and the WIMP-nucleon scattering cross section, since ρ{sub χ} must be rescaled with respect to the observed DM density in the neighborhood of the Sun when the calculated relic density Ω is smaller than the observed one Ω{sub 0}. As a consequence, a DM direct detection experiment is not directly sensitive to the physical cut-off scale of the EFT, but on some dimensional combination that does not depend on the actual value of Ω. However, such degeneracy

Cold dark matter plus not-so-clumpy dark relics

International Nuclear Information System (INIS)

Diamanti, Roberta; Ando, Shin'ichiro; Weniger, Christoph; Gariazzo, Stefano; Mena, Olga

2017-01-01

Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction f ncdm of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are f ncdm ≤0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are f ncdm ≤0.43 (0.45), respectively.

Cold dark matter plus not-so-clumpy dark relics

Energy Technology Data Exchange (ETDEWEB)

Diamanti, Roberta; Ando, Shin' ichiro; Weniger, Christoph [GRAPPA, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Gariazzo, Stefano; Mena, Olga, E-mail: r.diamanti@uva.nl, E-mail: s.ando@uva.nl, E-mail: gariazzo@to.infn.it, E-mail: omena@ific.uv.es, E-mail: c.weniger@uva.nl [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de Valencia, Apartado de Correos 22085, E-46071, Valencia (Spain)

2017-06-01

Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction f {sub ncdm} of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are f {sub ncdm}≤0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are f {sub ncdm}≤0.43 (0.45), respectively.

Detection of relic gravitational waves in thermal case by using Adv.LIGO data of GW150914

International Nuclear Information System (INIS)

Ghayour, Basem; Khodagholizadeh, Jafar

2017-01-01

The thermal spectrum of relic gravitational waves enhances the usual spectrum. Our analysis shows that there exist some chances for detection of the thermal spectrum in addition to the usual spectrum by comparison with sensitivity of Adv.LIGO of GW150914 and detector based on the maser light. The behavior of the inflation and reheating stages are often known as power law expansion like S(η) ∝ η"1"+"β, S(η) ∝ η"1"+"β"_s, respectively, with constraints 1 + β 0. The β and β_s have an unique effect on the shape of the spectrum. We find some values of the β and β_s by considering the mentioned comparison. As obtained, the results give us more information as regards the evolution of inflation and reheating stages. (orig.)

Detection of relic gravitational waves in thermal case by using Adv.LIGO data of GW150914

Energy Technology Data Exchange (ETDEWEB)

Ghayour, Basem [University of Hyderabad, School of Physics, Hyderabad (India); Khodagholizadeh, Jafar [Farhangian University, Tehran (Iran, Islamic Republic of)

2017-08-15

The thermal spectrum of relic gravitational waves enhances the usual spectrum. Our analysis shows that there exist some chances for detection of the thermal spectrum in addition to the usual spectrum by comparison with sensitivity of Adv.LIGO of GW150914 and detector based on the maser light. The behavior of the inflation and reheating stages are often known as power law expansion like S(η) ∝ η{sup 1+β}, S(η) ∝ η{sup 1+β{sub s}}, respectively, with constraints 1 + β < 0, 1 + β{sub s} > 0. The β and β{sub s} have an unique effect on the shape of the spectrum. We find some values of the β and β{sub s} by considering the mentioned comparison. As obtained, the results give us more information as regards the evolution of inflation and reheating stages. (orig.)

Relic gravitational waves and extended inflation

International Nuclear Information System (INIS)

Turner, M.S.; Wilczek, F.

1990-01-01

In extended inflation, a new version of inflation where the transition from an inflationary to a radiation-dominated Universe is accomplished by bubble nucleation, bubble collisions supply a potent---and potentially detectable---source of gravitational waves. The energy density in relic gravitons from bubble collisions is expected to be about 10 -5 of closure density. Their characteristic wavelength depends upon the reheating temperature T RH: λ∼(10 4 cm)[(10 14 GeV)/T RH ]. If black holes are produced by bubble collisions, they will evaporate producing shorter-wavelength gravitons

Impact of SUSY-QCD corrections on neutralino-stop co-annihilation and the neutralino relic density

Energy Technology Data Exchange (ETDEWEB)

Harz, Julia [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Herrmann, Bjoern [Savoie Univ./CNRS, Annecy-le-Vieux (France). LAPTh; Klasen, Michael [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Kovarik, Karol [Karlsruher Institut fuer Technologie, Karlsruhe (Germany). Inst. fuer Theoretische Physik; Le Boulc' h, Quentin [Grenoble Univ./CNRS-IN2P3/INPG, Grenoble (France). Lab. de Physique Subatomique et de Cosmologie

2013-02-15

We have calculated the full O({alpha}{sub s}) supersymmetric QCD corrections to neutralino-stop coannihilation into electroweak vector and Higgs bosons within the Minimal Supersymmetric Standard Model (MSSM).We performed a parameter study within the phenomenological MSSM and demonstrated that the studied co-annihilation processes are phenomenologically relevant, especially in the context of a 126 GeV Higgs-like particle. By means of an example scenario we discuss the effect of the full next-to-leading order corrections on the co-annihilation cross section and show their impact on the predicted neutralino relic density. We demonstrate that the impact of these corrections on the cosmologically preferred region of parameter space is larger than the current experimental uncertainty of WMAP data.

Relic density and CMB constraints on dark matter annihilation with Sommerfeld enhancement

International Nuclear Information System (INIS)

Zavala, Jesus; White, Simon D. M.; Vogelsberger, Mark

2010-01-01

We calculate how the relic density of dark matter particles is altered when their annihilation is enhanced by the Sommerfeld mechanism due to a Yukawa interaction between the annihilating particles. Maintaining a dark matter abundance consistent with current observational bounds requires the normalization of the s-wave annihilation cross section to be decreased compared to a model without enhancement. The level of suppression depends on the specific parameters of the particle model, with the kinetic decoupling temperature having the most effect. We find that the cross section can be reduced by as much as an order of magnitude for extreme cases. We also compute the μ-type distortion of the CMB energy spectrum caused by energy injection from such Sommerfeld-enhanced annihilation. Our results indicate that in the vicinity of resonances, associated with bound states, distortions can be large enough to be excluded by the upper limit |μ|≤9.0x10 -5 found by the FIRAS (Far Infrared Absolute Spectrophotometer) instrument on the COBE (Cosmic Background Explorer) satellite.

Radio observations of the double-relic galaxy cluster Abell 1240

Science.gov (United States)

Hoang, D. N.; Shimwell, T. W.; van Weeren, R. J.; Intema, H. T.; Röttgering, H. J. A.; Andrade-Santos, F.; Akamatsu, H.; Bonafede, A.; Brunetti, G.; Dawson, W. A.; Golovich, N.; Best, P. N.; Botteon, A.; Brüggen, M.; Cassano, R.; de Gasperin, F.; Hoeft, M.; Stroe, A.; White, G. J.

2018-05-01

We present LOFAR 120 - 168 MHz images of the merging galaxy cluster Abell 1240 that hosts double radio relics. In combination with the GMRT 595 - 629 MHz and VLA 2 - 4 GHz data, we characterised the spectral and polarimetric properties of the radio emission. The spectral indices for the relics steepen from their outer edges towards the cluster centre and the electric field vectors are approximately perpendicular to the major axes of the relics. The results are consistent with the picture that these relics trace large-scale shocks propagating outwards during the merger. Assuming diffusive shock acceleration (DSA), we obtain shock Mach numbers of M=2.4 and 2.3 for the northern and southern shocks, respectively. For M≲ 3 shocks, a pre-existing population of mildly relativistic electrons is required to explain the brightness of the relics due to the high (>10 per cent) particle acceleration efficiency required. However, for M≳ 4 shocks the required efficiency is ≳ 1% and ≳ 0.5%, respectively, which is low enough for shock acceleration directly from the thermal pool. We used the fractional polarization to constrain the viewing angle to ≥53 ± 3° and ≥39 ± 5° for the northern and southern shocks, respectively. We found no evidence for diffuse emission in the cluster central region. If the halo spans the entire region between the relics (˜1.8 Mpc) our upper limit on the power is P1.4GHz = (1.4 ± 0.6) × 1023 W Hz-1 which is approximately equal to the anticipated flux from a cluster of this mass. However, if the halo is smaller than this, our constraints on the power imply that the halo is underluminous.

The physics of relic neutrinos

International Nuclear Information System (INIS)

Dighe, A.; Pastor, S.; Smirnov, A.

1998-12-01

We report on the main results presented at the workshop on the Physics of Relic Neutrinos. The study of relic neutrinos involves a broad spectrum of problems in particle physics, astrophysics and cosmology. Features of baryogenesis and leptogenesis could be imprinted in the properties of the relic neutrino sea. Relic neutrinos played a crucial role in the big bang nucleosynthesis. Being the hot component of the dark matter, they have participated in the structure formation in the universe. Although the direct detection of the sea seems impossible at this stage, there could be various indirect manifestations of these neutrinos which would allow us to study the properties of the sea both in the past and at the present epoch. (author)

Relic gravitational waves and the generalized second law

International Nuclear Information System (INIS)

Izquierdo, German; Pavon, Diego

2004-01-01

The generalized second law of gravitational thermodynamics is applied to the present era of accelerated expansion of the Universe. In spite of the fact that the entropy of matter and relic gravitational waves inside the event horizon diminish, the mentioned law is fulfilled provided that the expression for the entropy density of the gravitational waves satisfies a certain condition

Imprints of relic gravitational waves in cosmic microwave background radiation

International Nuclear Information System (INIS)

Baskaran, D.; Grishchuk, L. P.; Polnarev, A. G.

2006-01-01

A strong variable gravitational field of the very early Universe inevitably generates relic gravitational waves by amplifying their zero-point quantum oscillations. We begin our discussion by contrasting the concepts of relic gravitational waves and inflationary 'tensor modes'. We explain and summarize the properties of relic gravitational waves that are needed to derive their effects on cosmic microwave background (CMB) temperature and polarization anisotropies. The radiation field is characterized by four invariants I, V, E, B. We reduce the radiative transfer equations to a single integral equation of Voltairre type and solve it analytically and numerically. We formulate the correlation functions C l XX ' for X, X ' =T, E, B and derive their amplitudes, shapes and oscillatory features. Although all of our main conclusions are supported by exact numerical calculations, we obtain them, in effect, analytically by developing and using accurate approximations. We show that the TE correlation at lower l's must be negative (i.e. an anticorrelation), if it is caused by gravitational waves, and positive if it is caused by density perturbations. This difference in TE correlation may be a signature more valuable observationally than the lack or presence of the BB correlation, since the TE signal is about 100 times stronger than the expected BB signal. We discuss the detection by WMAP of the TE anticorrelation at l≅30 and show that such an anticorrelation is possible only in the presence of a significant amount of relic gravitational waves (within the framework of all other common assumptions). We propose models containing considerable amounts of relic gravitational waves that are consistent with the measured TT, TE and EE correlations

Prospects for relic neutrino detection

International Nuclear Information System (INIS)

Smith, P.F.

1991-03-01

The standard big bang model predicts a universal background of relic neutrinos, comparable in number density to the background microwave photons. This neutrino background is undetectable at the present time firstly because the neutrino energy is very low (10 -4 -10 -5 eV) resulting in a very low energy transfer to any conceivable detector, and secondly the low energy gives a lower interaction cross section and hence a very low event rate per unit mass. These obstacles have so far precluded any realistic proposal for relic neutrino detection. The aim of this paper is to illustrate the difficulties in detecting these neutrinos by summarizing six detection ideas which have been previously considered, indicating in each case the problems which have prevented the idea being developed into an experimental proposal. The most promising direction for further study would appear to be that of coherent interactions. So far, no investigations of this idea have resulted in a practical detection scheme, but in this paper one new variation is suggested which could in principle give an observable effect, if the necessary stringent experimental conditions could be created. It is suggested that this may become possible with the aid of foreseeable 21st century developments in nanotechnology. (author)

Galaxy Cluster Outskirts from the Thermal SZ and Non-Thermal Synchrotron Link

Directory of Open Access Journals (Sweden)

Kaustuv Basu

2016-11-01

Full Text Available Galaxy cluster merger shocks are the main agent for the thermalization of the intracluster medium and the energization of cosmic ray particles in it. Shock propagation changes the state of the tenuous intracluster plasma, and the corresponding signal variations are measurable with the current generation of X-ray and Sunyaev–Zel’dovich (SZ effect instruments. Additionally, non-thermal electrons (re-energized by the shocks sometimes give rise to extended and luminous synchrotron sources known as radio relics, which are prominent indicators of shocks propagating roughly in the plane of the sky. In this short review, we discuss how the joint modeling of the non-thermal and thermal signal variations across radio relic shock fronts is helping to advance our knowledge of the gas thermodynamical properties and magnetic field strengths in the cluster outskirts. We describe the first use of the SZ effect to measure the Mach numbers of relic shocks, for both the nearest (Coma and the farthest (El Gordo clusters with known radio relics.

Relic gravitational waves and cosmology

International Nuclear Information System (INIS)

Grishchuk, Leonid P

2005-01-01

The paper begins with a brief recollection of interactions of the author with Ya B Zeldovich in the context of the study of relic gravitational waves. The principles and early results on the quantum-mechanical generation of cosmological perturbations are then summarized. The expected amplitudes of relic gravitational waves differ in various frequency windows, and therefore the techniques and prospects of their detection are distinct. One section of the paper describes the present state of efforts in direct detection of relic gravitational waves. Another section is devoted to indirect detection via the anisotropy and polarization measurements of the cosmic microwave background (CMB) radiation. It is emphasized throughout the paper that the inference about the existence and expected amount of relic gravitational waves is based on a solid theoretical foundation and the best available cosmological observations. It is also explained in great detail what went wrong with the so-called 'inflationary gravitational waves', whose amount is predicted by inflationary theorists to be negligibly small, thus depriving them of any observational significance. (reviews of topical problems)

Superheavy thermal dark matter and primordial asymmetries

International Nuclear Information System (INIS)

Bramante, Joseph; Unwin, James

2017-01-01

The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10 10 GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

Superheavy thermal dark matter and primordial asymmetries

Energy Technology Data Exchange (ETDEWEB)

Bramante, Joseph [Perimeter Institute for Theoretical Physics,31 Caroline St N, Waterloo, ON N2L 2Y5 (Canada); Unwin, James [Department of Physics, University of Illinois at Chicago,845 W Taylor St, Chicago, IL 60607 (United States)

2017-02-23

The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10{sup 10} GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

Research on Splicing Method of Digital Relic Fragment Model

Science.gov (United States)

Yan, X.; Hu, Y.; Hou, M.

2018-04-01

In the course of archaeological excavation, a large number of pieces of cultural relics were unearthed, and the restoration of these fragments was done manually by traditional arts and crafts experts. In this process, cultural relics experts often try to splice the existing cultural relics, and then use adhesive to stick together the fragments of correct location, which will cause irreversible secondary damage to cultural relics. In order to minimize such damage, the surveyors combine 3D laser scanning with computer technology, and use the method of establishing digital cultural relics fragments model to make virtual splicing of cultural relics. The 3D software on the common market can basically achieve the model translation and rotation, using this two functions can be achieved manually splicing between models, mosaic records after the completion of the specific location of each piece of fragments, so as to effectively reduce the damage to the relics had tried splicing process.

Relic gravitational waves and extended inflation

International Nuclear Information System (INIS)

Turner, M.S.; Wilczek, F.

1990-08-01

In extended inflation, a new version of inflation where the transition from the false-vacuum phase to a radiation-dominated Universe is accomplished by bubble nucleation and percolation, bubble collisions supply a potent-and potentially detectable-source of gravitational waves. The present energy density in relic gravity waves from bubble collisions is expected to be about 10(exp -5) of closure density-many orders of magnitude greater than that of the gravity waves produced by quantum fluctuations. Their characteristic wavelength depends upon the reheating temperature T(sub RH): lambda is approximately 10(exp 4) cm (10(exp 14) GeV/T(sub RH)). If large numbers of black holes are produced, a not implausible outcome, they will evaporate producing comparable amounts of shorter wavelength waves, lambda is approximately 10(exp -6) cm (T(sub RH)/10(exp 14) GeV)

Application of 3d Model of Cultural Relics in Virtual Restoration

Science.gov (United States)

Zhao, S.; Hou, M.; Hu, Y.; Zhao, Q.

2018-04-01

In the traditional cultural relics splicing process, in order to identify the correct spatial location of the cultural relics debris, experts need to manually splice the existing debris. The repeated contact between debris can easily cause secondary damage to the cultural relics. In this paper, the application process of 3D model of cultural relic in virtual restoration is put forward, and the relevant processes and ideas are verified with the example of Terracotta Warriors data. Through the combination of traditional cultural relics restoration methods and computer virtual reality technology, virtual restoration of high-precision 3D models of cultural relics can provide a scientific reference for virtual restoration, avoiding the secondary damage to the cultural relics caused by improper restoration. The efficiency and safety of the preservation and restoration of cultural relics have been improved.

APPLICATION OF 3D MODEL OF CULTURAL RELICS IN VIRTUAL RESTORATION

Directory of Open Access Journals (Sweden)

S. Zhao

2018-04-01

Full Text Available In the traditional cultural relics splicing process, in order to identify the correct spatial location of the cultural relics debris, experts need to manually splice the existing debris. The repeated contact between debris can easily cause secondary damage to the cultural relics. In this paper, the application process of 3D model of cultural relic in virtual restoration is put forward, and the relevant processes and ideas are verified with the example of Terracotta Warriors data. Through the combination of traditional cultural relics restoration methods and computer virtual reality technology, virtual restoration of high-precision 3D models of cultural relics can provide a scientific reference for virtual restoration, avoiding the secondary damage to the cultural relics caused by improper restoration. The efficiency and safety of the preservation and restoration of cultural relics have been improved.

The radio relics and halo of El Gordo, a massive z = 0.870 cluster merger

Energy Technology Data Exchange (ETDEWEB)

Lindner, Robert R.; Baker, Andrew J.; Hughes, John P. [Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Battaglia, Nick [McWilliams Center for Cosmology, Wean Hall, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States); Gupta, Neeraj [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands); Knowles, Kenda; Moodley, Kavilan [Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, Durban 4041 (South Africa); Marriage, Tobias A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686 (United States); Menanteau, Felipe [National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W. Clark St., Urbana, IL 61801 (United States); Reese, Erik D. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd St., Philadelphia, PA 19104 (United States); Srianand, Raghunathan, E-mail: rlindner@astro.wisc.edu [IUCAA, Ganeshkhind, Pune 411007 (India)

2014-05-01

We present 610 MHz and 2.1 GHz imaging of the massive Sunyaev-Zel'dovich Effect selected z = 0.870 cluster merger ACT-CL J0102–4915 ({sup E}l Gordo{sup )}, obtained with the Giant Metrewave Radio Telescope and the Australia Telescope Compact Array (ATCA), respectively. We detect two complexes of radio relics separated by 3.'4 (1.6 Mpc) along the system's northwest-to-southeast collision axis that have high integrated polarization fractions (33%) and steep spectral indices (α between 1 and 2; S {sub ν}∝ν{sup –α}), consistent with creation via Fermi acceleration by shocks in the intracluster medium triggered by the cluster collision. From the spectral index of the relics, we compute a Mach number M=2.5{sub −0.3}{sup +0.7} and shock speed of 2500{sub −300}{sup +400} km s{sup −1}. With our wide-bandwidth, full-polarization ATCA data, we compute the Faraday depth φ across the northwest relic and find a range of values spanning Δφ = 30 rad m{sup –2}, with a mean value of (φ) = 11 rad m{sup –2} and standard deviation σ{sub φ} = 6 rad m{sup –2}. With the integrated line-of-sight gas density derived from new Chandra X-ray observations, our Faraday depth measurement implies B {sub ∥} ∼ 0.01 μG in the cluster outskirts. The extremely narrow shock widths in the relics (d {sub shock} ≤ 23 kpc), caused by the short synchrotron cooling timescale of relativistic electrons at z = 0.870, prevent us from placing a meaningful constraint on the magnetic field strength B using cooling time arguments. In addition to the relics, we detect a large (r {sub H} ≅ 1.1 Mpc radius), powerful (log (L {sub 1.4}/W Hz{sup –1}) = 25.66 ± 0.12) radio halo with a shape similar to El Gordo's 'bullet'-like X-ray morphology. The spatially resolved spectral-index map of the halo shows the synchrotron spectrum is flattest near the relics, along the system's collision axis, and in regions of high T {sub gas}, all locations associated

Dark matter relics and the expansion rate in scalar-tensor theories

Energy Technology Data Exchange (ETDEWEB)

Dutta, Bhaskar; Jimenez, Esteban [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Zavala, Ivonne, E-mail: dutta@physics.tamu.edu, E-mail: este1985@physics.tamu.edu, E-mail: e.i.zavalacarrasco@swansea.ac.uk [Department of Physics, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

2017-06-01

We study the impact of a modified expansion rate on the dark matter relic abundance in a class of scalar-tensor theories. The scalar-tensor theories we consider are motivated from string theory constructions, which have conformal as well as disformally coupled matter to the scalar. We investigate the effects of such a conformal coupling to the dark matter relic abundance for a wide range of initial conditions, masses and cross-sections. We find that exploiting all possible initial conditions, the annihilation cross-section required to satisfy the dark matter content can differ from the thermal average cross-section in the standard case. We also study the expansion rate in the disformal case and find that physically relevant solutions require a nontrivial relation between the conformal and disformal functions. We study the effects of the disformal coupling in an explicit example where the disformal function is quadratic.

Stochastic backgrounds of relic gravitons, T$\\Lambda$CDM paradigm and the stiff ages

CERN Document Server

Giovannini, Massimo

2008-01-01

Absent any indirect tests on the thermal history of the Universe prior to the formation of light nuclear elements, it is legitimate to investigate situations where, before nucleosyntheis, the sound speed of the plasma was larger than $c/\\sqrt{3}$, at most equalling the speed of light $c$. In this plausible extension of the current cosmological paradigm, hereby dubbed Tensor-$\\Lambda$CDM (i.e. T$\\Lambda$CDM) scenario, high-frequency gravitons are copiously produced. Without conflicting with the bounds on the tensor to scalar ratio stemming from the combined analysis of the three standard cosmological data sets (i.e. cosmic microwave background anisotropies, large-scale structure and supenovae), the spectral energy density of the relic gravitons in the T$\\Lambda$CDM scenario can be potentially observable by wide-band interferometers (in their advanced version) operating in a frequency window which ranges between few Hz and few kHz.

The Thermal Entropy Density of Spacetime

Directory of Open Access Journals (Sweden)

Rongjia Yang

2013-01-01

Full Text Available Introducing the notion of thermal entropy density via the first law of thermodynamics and assuming the Einstein equation as an equation of thermal state, we obtain the thermal entropy density of any arbitrary spacetime without assuming a temperature or a horizon. The results confirm that there is a profound connection between gravity and thermodynamics.

Exploration and implementation of ontology-based cultural relic knowledge map integration platform

Science.gov (United States)

Yang, Weiqiang; Dong, Yiqiang

2018-05-01

To help designers to better carry out creative design and improve the ability of searching traditional cultural relic information, the ontology-based knowledge map construction method was explored and an integrated platform for cultural relic knowledge map was developed. First of all, the construction method of the ontology of cultural relics was put forward, and the construction of the knowledge map of cultural relics was completed based on the constructed cultural relic otology. Then, a personalized semantic retrieval framework for creative design was proposed. Finally, the integrated platform of the knowledge map of cultural relics was designed and realized. The platform was divided into two parts. One was the foreground display system, which was used for designers to search and browse cultural relics. The other was the background management system, which was for cultural experts to manage cultural relics' knowledge. The research results showed that the platform designed could improve the retrieval ability of cultural relic information. To sum up, the platform can provide a good support for the designer's creative design.

Can Planck-mass relics of evaporating black holes close the Universe

International Nuclear Information System (INIS)

MacGibbon, J.H.

1987-01-01

The authors propose that the cosmological dark matter consists of the Planck-mass remnants of evaporating primordial black holes. Such remnants would be expected to have close to the critical density if the black holes evaporating at the present epoch have the maximum density consistent with cosmic-ray constraints. Primordial black holes of the required density may form naturally at the end of an inflationary epoch. Planck-mass relics would behave dynamically just like 'cold dark matter' and would therefore share the attractions of other 'cold' candidates. In addition, because the baryonic matter in black holes cannot participate in nucleosynthesis the limits on the baryonic content of the Universe set by primordial nucleosynthesis are circumvented. (author)

SCRMS: An RFID and Sensor Web-Enabled Smart Cultural Relics Management System.

Science.gov (United States)

Xiao, Changjiang; Chen, Nengcheng; Li, Dandan; Lv, You; Gong, Jianya

2016-12-30

Cultural relics represent national or even global resources of inestimable value. How to efficiently manage and preserve these cultural relics is a vitally important issue. To achieve this goal, this study proposed, designed, and implemented an RFID and Sensor Web-enabled smart cultural relics management system (SCRMS). In this system, active photovoltaic subtle energy-powered Radio Frequency Identification (RFID) is used for long-range contactless identification and lifecycle management of cultural relics during their storage and circulation. In addition, different types of ambient sensors are integrated with the RFID tags and deployed around cultural relics to monitor their environmental parameters, helping to ensure that they remain in good condition. An Android-based smart mobile application, as middleware, is used in collaboration with RFID readers to collect information and provide convenient management for the circulation of cultural relics. Moreover, multiple sensing techniques are taken advantage of simultaneously for preservation of cultural relics. The proposed system was successfully applied to a museum in the Yongding District, Fujian Province, China, demonstrating its feasibility and advantages for smart and efficient management and preservation of cultural relics.

SCRMS: An RFID and Sensor Web-Enabled Smart Cultural Relics Management System

Directory of Open Access Journals (Sweden)

Changjiang Xiao

2016-12-01

Full Text Available Cultural relics represent national or even global resources of inestimable value. How to efficiently manage and preserve these cultural relics is a vitally important issue. To achieve this goal, this study proposed, designed, and implemented an RFID and Sensor Web–enabled smart cultural relics management system (SCRMS. In this system, active photovoltaic subtle energy-powered Radio Frequency Identification (RFID is used for long-range contactless identification and lifecycle management of cultural relics during their storage and circulation. In addition, different types of ambient sensors are integrated with the RFID tags and deployed around cultural relics to monitor their environmental parameters, helping to ensure that they remain in good condition. An Android-based smart mobile application, as middleware, is used in collaboration with RFID readers to collect information and provide convenient management for the circulation of cultural relics. Moreover, multiple sensing techniques are taken advantage of simultaneously for preservation of cultural relics. The proposed system was successfully applied to a museum in the Yongding District, Fujian Province, China, demonstrating its feasibility and advantages for smart and efficient management and preservation of cultural relics.

Twin radio relics in the nearby low-mass galaxy cluster Abell 168

Science.gov (United States)

Dwarakanath, K. S.; Parekh, V.; Kale, R.; George, L. T.

2018-06-01

We report the discovery of twin radio relics in the outskirts of the low-mass merging galaxy cluster Abell 168 (redshift=0.045). One of the relics is elongated with a linear extent ˜800 kpc and projected width of ˜80 kpc and is located ˜900 kpc towards the north of the cluster centre, oriented roughly perpendicular to the major axis of the X-ray emission. The second relic is ring-shaped with a size ˜220 kpc and is located near the inner edge of the elongated relic at a distance of ˜600 kpc from the cluster centre. These radio sources were imaged at 323 and 608 MHz with the Giant Meterwave Radio Telescope and at 1520 MHz with the Karl G. Jansky Very Large Array (VLA). The elongated relic was detected at all frequencies, with a radio power of 1.38 ± 0.14 × 1023 W Hz-1 at 1.4 GHz and a power law in the frequency range 70-1500 MHz (S ∝ να, α = -1.1 ± 0.04). This radio power is in good agreement with that expected from the known empirical relation between the radio powers of relics and host cluster masses. This is the lowest mass (M500 = 1.24 × 1014 M⊙) cluster in which relics due to merger shocks are detected. The ring-shaped relic has a steeper spectral index (α) of -1.74 ± 0.29 in the frequency range 100-600 MHz. We propose this relic to be an old plasma, revived due to adiabatic compression by the outgoing shock that produced the elongated relic.

GALAXY CLUSTER RADIO RELICS IN ADAPTIVE MESH REFINEMENT COSMOLOGICAL SIMULATIONS: RELIC PROPERTIES AND SCALING RELATIONSHIPS

International Nuclear Information System (INIS)

Skillman, Samuel W.; Hallman, Eric J.; Burns, Jack O.; Smith, Britton D.; O'Shea, Brian W.; Turk, Matthew J.

2011-01-01

Cosmological shocks are a critical part of large-scale structure formation, and are responsible for heating the intracluster medium in galaxy clusters. In addition, they are capable of accelerating non-thermal electrons and protons. In this work, we focus on the acceleration of electrons at shock fronts, which is thought to be responsible for radio relics-extended radio features in the vicinity of merging galaxy clusters. By combining high-resolution adaptive mesh refinement/N-body cosmological simulations with an accurate shock-finding algorithm and a model for electron acceleration, we calculate the expected synchrotron emission resulting from cosmological structure formation. We produce synthetic radio maps of a large sample of galaxy clusters and present luminosity functions and scaling relationships. With upcoming long-wavelength radio telescopes, we expect to see an abundance of radio emission associated with merger shocks in the intracluster medium. By producing observationally motivated statistics, we provide predictions that can be compared with observations to further improve our understanding of magnetic fields and electron shock acceleration.

Relic gravitational waves from light primordial black holes

International Nuclear Information System (INIS)

Dolgov, Alexander D.; Ejlli, Damian

2011-01-01

The energy density of relic gravitational waves (GWs) emitted by primordial black holes (PBHs) is calculated. We estimate the intensity of GWs produced at quantum and classical scattering of PBHs, the classical graviton emission from the PBH binaries in the early Universe, and the graviton emission due to PBH evaporation. If nonrelativistic PBHs dominated the cosmological energy density prior to their evaporation, the probability of formation of dense clusters of PBHs and their binaries in such clusters would be significant and the energy density of the generated gravitational waves in the present-day universe could exceed that produced by other known mechanisms. The intensity of these gravitational waves would be maximal in the GHz frequency band of the spectrum or higher and makes their observation very difficult by present detectors but also gives a rather good possibility to investigate it by present and future high-frequency gravitational waves electromagnetic detectors. However, the low-frequency part of the spectrum in the range f∼0.1-10 Hz may be detectable by the planned space interferometers DECIGO/BBO. For sufficiently long duration of the PBH matter-dominated stage, the cosmological energy fraction of GWs from inflation would be noticeably diluted.

Supernova relic electron neutrinos and anti-neutrinos in future large-scale observatories

International Nuclear Information System (INIS)

Volpe, C.; Welzel, J.

2007-01-01

We investigate the signal from supernova relic neutrinos in future large scale observatories, such as MEMPHYS (UNO, Hyper-K), LENA and GLACIER, at present under study. We discuss that complementary information might be gained from the observation of supernova relic electron antineutrinos and neutrinos using the scattering on protons on one hand, and on nuclei such as oxygen, carbon or argon on the other hand. When determining the relic neutrino fluxes we also include, for the first time, the coupling of the neutrino magnetic moment to magnetic fields within the core collapse supernova. We present numerical results on both the relic ν e and ν-bar e fluxes and on the number of events for ν e + C 12 , ν e + O 16 , ν e + Ar 40 and ν-bar e + p for various oscillation scenarios. The observation of supernova relic neutrinos might provide us with unique information on core-collapse supernova explosions, on the star formation history and on neutrino properties, that still remain unknown. (authors)

Calculation of momentum distribution function of a non-thermal fermionic dark matter

Energy Technology Data Exchange (ETDEWEB)

Biswas, Anirban; Gupta, Aritra, E-mail: anirbanbiswas@hri.res.in, E-mail: aritra@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India)

2017-03-01

The most widely studied scenario in dark matter phenomenology is the thermal WIMP scenario. Inspite of numerous efforts to detect WIMP, till now we have no direct evidence for it. A possible explanation for this non-observation of dark matter could be because of its very feeble interaction strength and hence, failing to thermalise with the rest of the cosmic soup. In other words, the dark matter might be of non-thermal origin where the relic density is obtained by the so-called freeze-in mechanism. Furthermore, if this non-thermal dark matter is itself produced substantially from the decay of another non-thermal mother particle, then their distribution functions may differ in both size and shape from the usual equilibrium distribution function. In this work, we have studied such a non-thermal (fermionic) dark matter scenario in the light of a new type of U(1){sub B−L} model. The U(1){sub B−L} model is interesting, since, besides being anomaly free, it can give rise to neutrino mass by Type II see-saw mechanism. Moreover, as we will show, it can accommodate a non-thermal fermionic dark matter as well. Starting from the collision terms, we have calculated the momentum distribution function for the dark matter by solving a coupled system of Boltzmann equations. We then used it to calculate the final relic abundance, as well as other relevant physical quantities. We have also compared our result with that obtained from solving the usual Boltzmann (or rate) equations directly in terms of comoving number density, Y . Our findings suggest that the latter approximation is valid only in cases where the system under study is close to equilibrium, and hence should be used with caution.

An Account of Translation of Relics: the Writings of Alonso de Cartagena

Directory of Open Access Journals (Sweden)

Luis Fernández Gallardo

2018-01-01

Full Text Available The narratives of translation of relics is a genre of devotional literature that didn´t develop extensively in Medieval Castile. But Alonso de Cartagena contributed to it remarkably. In 1453, during a pastoral visit, he decided to move the relics of St. Juliana to a more honorable place. He wrote an account of these facts that adjusts strictly to the features of the genre. This vernacular text contains an exposition about the cult of saints and their relics, which has an intense Thomist inspiration: it sets theological questions with precision and clarity. The provisions on the decoration of the chapel of the relics offer an interesting testimony of the debate on religious image which is then developed in Castile.

a Review of Digital Watermarking and Copyright Control Technology for Cultural Relics

Science.gov (United States)

Liu, H.; Hou, M.; Hu, Y.

2018-04-01

With the rapid growth of the application and sharing of the 3-D model data in the protection of cultural relics, the problem of Shared security and copyright control of the three-dimensional model of cultural relics is becoming increasingly prominent. Followed by a digital watermarking copyright control has become the frontier technology of 3-D model security protection of cultural relics and effective means, related technology research and application in recent years also got further development. 3-D model based on cultural relics digital watermarking and copyright control technology, introduces the research background and demand, its unique characteristics were described, and its development and application of the algorithm are discussed, and the prospects of the future development trend and some problems and the solution.

Radiological data acquisition, investigation and evaluation of mining relics

International Nuclear Information System (INIS)

1992-01-01

Within the scope of a Federal Project, the environmental radioactivity and the radon concentration in buildings caused by mining relics in the new Federal Lands of Germany are investigated. In the first phase of the project, about 8000 relics of former mining were identified by analysing existing documents, categorised, and recorded in a special data bank. Thereby, 'areas of suspicion' of 1500 km 2 spaciously defined in the beginning could be reduced to 'areas of investigation' of 250 km 2 now to be examined in close coordination with the land and district authorities by a programme gradually adapted to the radiological significance of the relics. Experience with site-specific measuring programmes have already been gained through three pilot projects at typical sites of former mining activities. Recommendations of the German Radiation Protection Commission serve for the evaluation of the results. By the measuring programme for radon in buildings of mining and geological predestined regions more than 25000 buildings of 210 communities have been investigated. The results confirm the expected prevailing influence of the geologic underground on the radon concentration. Extreme values are observed where direct connections additionally exist to mining relics in the ground. (orig./HP) With 11 figs. in annex [de

Supernova relic electron neutrinos and anti-neutrinos in future large-scale observatories

Energy Technology Data Exchange (ETDEWEB)

Volpe, C.; Welzel, J. [Institut de Physique Nuclueaire, 91 - Orsay (France)

2007-07-01

We investigate the signal from supernova relic neutrinos in future large scale observatories, such as MEMPHYS (UNO, Hyper-K), LENA and GLACIER, at present under study. We discuss that complementary information might be gained from the observation of supernova relic electron antineutrinos and neutrinos using the scattering on protons on one hand, and on nuclei such as oxygen, carbon or argon on the other hand. When determining the relic neutrino fluxes we also include, for the first time, the coupling of the neutrino magnetic moment to magnetic fields within the core collapse supernova. We present numerical results on both the relic {nu}{sub e} and {nu}-bar{sub e} fluxes and on the number of events for {nu}{sub e} + C{sup 12}, {nu}{sub e} + O{sup 16}, {nu}{sub e} + Ar{sup 40} and {nu}-bar{sub e} + p for various oscillation scenarios. The observation of supernova relic neutrinos might provide us with unique information on core-collapse supernova explosions, on the star formation history and on neutrino properties, that still remain unknown. (authors)

Relic right-handed Dirac neutrinos and implications for detection of cosmic neutrino background

Directory of Open Access Journals (Sweden)

Jue Zhang

2016-02-01

Full Text Available It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos νL and right-handed antineutrinos ν‾R in future experiments of neutrino capture on beta-decaying nuclei (e.g., νe+H3→He3+e− for the PTOLEMY experiment is likely to distinguish between Majorana and Dirac neutrinos, since the capture rate is twice larger in the former case. In this paper, we investigate the possible impact of right-handed neutrinos on the capture rate, assuming that massive neutrinos are Dirac particles and both right-handed neutrinos νR and left-handed antineutrinos ν‾L can be efficiently produced in the early Universe. It turns out that the capture rate can be enhanced at most by 28% due to the presence of relic νR and ν‾L with a total number density of 95 cm−3, which should be compared to the number density 336 cm−3 of cosmic neutrino background. The enhancement has actually been limited by the latest cosmological and astrophysical bounds on the effective number of neutrino generations Neff=3.14−0.43+0.44 at the 95% confidence level. For illustration, two possible scenarios have been proposed for thermal production of right-handed neutrinos in the early Universe.

micrOMEGAs 2.0.7: a program to calculate the relic density of dark matter in a generic model

Science.gov (United States)

Bélanger, G.; Boudjema, F.; Pukhov, A.; Semenov, A.

2007-12-01

micrOMEGAs2.0.7 is a code which calculates the relic density of a stable massive particle in an arbitrary model. The underlying assumption is that there is a conservation law like R-parity in supersymmetry which guarantees the stability of the lightest odd particle. The new physics model must be incorporated in the notation of CalcHEP, a package for the automatic generation of squared matrix elements. Once this is done, all annihilation and coannihilation channels are included automatically in any model. Cross-sections at v=0, relevant for indirect detection of dark matter, are also computed automatically. The package includes three sample models: the minimal supersymmetric standard model (MSSM), the MSSM with complex phases and the NMSSM. Extension to other models, including non supersymmetric models, is described. Program summaryTitle of program:micrOMEGAs2.0.7 Catalogue identifier:ADQR_v2_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADQR_v2_1.html Program obtainable from: CPC Program Library, Queen's University of 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.:216 529 No. of bytes in distributed program, including test data, etc.:1 848 816 Distribution format:tar.gz Programming language used:C and Fortran Computer:PC, Alpha, Mac, Sun Operating system:UNIX (Linux, OSF1, SunOS, Darwin, Cygwin) RAM:17 MB depending on the number of processes required Classification:1.9, 11.6 Catalogue identifier of previous version:ADQR_v2_0 Journal version of previous version:Comput. Phys. Comm. 176 (2007) 367 Does the new version supersede the previous version?:Yes Nature of problem:Calculation of the relic density of the lightest stable particle in a generic new model of particle physics. Solution method:In numerically solving the evolution equation for the density of dark matter, relativistic formulae for the thermal average are used. All tree

Cosmic relics from the big bang

International Nuclear Information System (INIS)

Hall, L.J.

1988-12-01

A brief introduction to the big bang picture of the early universe is given. Dark matter is discussed; particularly its implications for elementary particle physics. A classification scheme for dark matter relics is given. 21 refs., 11 figs., 1 tab

Cosmic relics from the big bang

Energy Technology Data Exchange (ETDEWEB)

Hall, L.J.

1988-12-01

A brief introduction to the big bang picture of the early universe is given. Dark matter is discussed; particularly its implications for elementary particle physics. A classification scheme for dark matter relics is given. 21 refs., 11 figs., 1 tab.

Another shock for the Bullet cluster, and the source of seed electrons for radio relics

Science.gov (United States)

Shimwell, Timothy W.; Markevitch, Maxim; Brown, Shea; Feretti, Luigina; Gaensler, B. M.; Johnston-Hollitt, M.; Lage, Craig; Srinivasan, Raghav

2015-05-01

With Australia Telescope Compact Array observations, we detect a highly elongated Mpc-scale diffuse radio source on the eastern periphery of the Bullet cluster 1E 0657-55.8, which we argue has the positional, spectral and polarimetric characteristics of a radio relic. This powerful relic (2.3 ± 0.1 × 1025 W Hz-1) consists of a bright northern bulb and a faint linear tail. The bulb emits 94 per cent of the observed radio flux and has the highest surface brightness of any known relic. Exactly coincident with the linear tail, we find a sharp X-ray surface brightness edge in the deep Chandra image of the cluster - a signature of a shock front in the hot intracluster medium (ICM), located on the opposite side of the cluster to the famous bow shock. This new example of an X-ray shock coincident with a relic further supports the hypothesis that shocks in the outer regions of clusters can form relics via diffusive shock (re-)acceleration. Intriguingly, our new relic suggests that seed electrons for reacceleration are coming from a local remnant of a radio galaxy, which we are lucky to catch before its complete disruption. If this scenario, in which a relic forms when a shock crosses a well-defined region of the ICM polluted with aged relativistic plasma - as opposed to the usual assumption that seeds are uniformly mixed in the ICM - is also the case for other relics, this may explain a number of peculiar properties of peripheral relics.

Analysis on the environment of cultural relic as tourist attraction--take Yungang Grottoes as an example

Science.gov (United States)

Xiangdong, Zhu; Jie, Bai

2018-03-01

Cultural relic resources are precious non-renewable resources and an important cornerstone for the development of cultural relic tourism. With the rapid development of tourism industry, the native environment of cultural relics is being squeezed constantly. Meanwhile, under the economic interests, cultural relic’s protection and heritage tourism contradictions continue to intensify. The present era which the architectural style is convergence, cultural relics protection is simplistic, restore historical sites blindly and other. In the historical process of economic development and the acceleration of new-type urbanization, the heritage industry faces the dual tasks and development challenges. As cultural relic protection workers, investigation of the utilization of cultural relic’s tourist attractions, investigation and analysis of the Yungang Grottoes, indicating cultural relics as a tourist attraction, not only to strengthen the protection of ontology, also should attach importance to the coordinated development of the protection of cultural relics and the utilization of tourism.

Relic gravitons and viscous cosmologies

International Nuclear Information System (INIS)

Cataldo, Mauricio; Mella, Patricio

2006-01-01

Previously it was shown that there exists a class of viscous cosmological models which violate the dominant energy condition for a limited amount of time after which they are smoothly connected to the ordinary radiation era (which preserves the dominant energy conditions). This violation of the dominant energy condition at an early cosmological epoch may influence the slopes of energy spectra of relic gravitons that might be of experimental relevance. However, the bulk viscosity coefficient of these cosmologies became negative during the ordinary radiation era, and then the entropy of the sources driving the geometry decreases with time. We show that in the presence of viscous sources with a linear barotropic equation of state p=γρ we get viscous cosmological models with positive bulk viscous stress during all their evolution, and hence the matter entropy increases with the expansion time. In other words, in the framework of viscous cosmologies, there exist isotropic models compatible with the standard second law of thermodynamics which also may influence the slopes of energy spectra of relic gravitons

TURBULENT COSMIC-RAY REACCELERATION AT RADIO RELICS AND HALOS IN CLUSTERS OF GALAXIES

International Nuclear Information System (INIS)

Fujita, Yutaka; Takizawa, Motokazu; Yamazaki, Ryo; Akamatsu, Hiroki; Ohno, Hiroshi

2015-01-01

Radio relics are synchrotron emission found on the periphery of galaxy clusters. From the position and the morphology, it is often believed that the relics are generated by cosmic-ray (CR) electrons accelerated at shocks through a diffusive shock acceleration (DSA) mechanism. However, some radio relics have harder spectra than the prediction of the standard DSA model. One example is observed in the cluster 1RXS J0603.3+4214, which is often called the “Toothbrush Cluster.” Interestingly, the position of the relic is shifted from that of a possible shock. In this study, we show that these discrepancies in the spectrum and the position can be solved if turbulent (re)acceleration is very effective behind the shock. This means that for some relics turbulent reacceleration may be the main mechanism to produce high-energy electrons, contrary to the common belief that it is the DSA. Moreover, we show that for efficient reacceleration, the effective mean free path of the electrons has to be much smaller than their Coulomb mean free path. We also study the merging cluster 1E 0657−56, or the “Bullet Cluster,” in which a radio relic has not been found at the position of the prominent shock ahead of the bullet. We indicate that a possible relic at the shock is obscured by the observed large radio halo that is generated by strong turbulence behind the shock. We propose a simple explanation of the morphological differences of radio emission among the Toothbrush, the Bullet, and the Sausage (CIZA J2242.8+5301) Clusters

The 'relics of Joan of Arc'

DEFF Research Database (Denmark)

Charlier, P.; Poupon, J.; Eb, A.

2010-01-01

Archaeological remains can provide concrete cases, making it possible to develop, refine or validate medico-legal techniques. In the case of the so-called 'Joan of Arc's relics' (a group of bone and archaeological remains known as the 'Bottle of Chinon'), 14 specialists analysed the samples such ...

PeV IceCube signals and Dark Matter relic abundance in modified cosmologies

Science.gov (United States)

Lambiase, G.; Mohanty, S.; Stabile, An.

2018-04-01

The discovery by the IceCube experiment of a high-energy astrophysical neutrino flux with energies of the order of PeV, has opened new scenarios in astroparticles physics. A possibility to explain this phenomenon is to consider the minimal models of Dark Matter (DM) decay, the 4-dimensional operator ˜ y_{α χ }\\overline{{L_{L_{α }}}} H χ , which is also able to generate the correct abundance of DM in the Universe. Assuming that the cosmological background evolves according to the standard cosmological model, it follows that the rate of DM decay Γ _χ ˜ |y_{α χ }|^2 needed to get the correct DM relic abundance (Γ _χ ˜ 10^{-58}) differs by many orders of magnitude with respect that one needed to explain the IceCube data (Γ _χ ˜ 10^{-25}), making the four-dimensional operator unsuitable. In this paper we show that assuming that the early Universe evolution is governed by a modified cosmology, the discrepancy between the two the DM decay rates can be reconciled, and both the IceCube neutrino rate and relic density can be explained in a minimal model.

On the absence of radio haloes in clusters with double relics

Science.gov (United States)

Bonafede, A.; Cassano, R.; Brüggen, M.; Ogrean, G. A.; Riseley, C. J.; Cuciti, V.; de Gasperin, F.; Golovich, N.; Kale, R.; Venturi, T.; van Weeren, R. J.; Wik, D. R.; Wittman, D.

2017-09-01

Pairs of radio relics are believed to form during cluster mergers, and are best observed when the merger occurs in the plane of the sky. Mergers can also produce radio haloes, through complex processes likely linked to turbulent re-acceleration of cosmic ray electrons. However, only some clusters with double relics also show a radio halo. Here, we present a novel method to derive upper limits on the radio halo emission, and analyse archival X-ray Chandra data, as well as galaxy velocity dispersions and lensing data, in order to understand the key parameter that switches on radio halo emission. We place upper limits on the halo power below the P1.4 GHz-M500 correlation for some clusters, confirming that clusters with double relics have different radio properties. Computing X-ray morphological indicators, we find that clusters with double relics are associated with the most disturbed clusters. We also investigate the role of different mass-ratios and time-since-merger. Data do not indicate that the merger mass-ratio has an impact on the presence or absence of radio haloes (the null hypothesis that the clusters belong to the same group cannot be rejected). However, the data suggest that the absence of radio haloes could be associated with early and late mergers, but the sample is too small to perform a statistical test. Our study is limited by the small number of clusters with double relics. Future surveys with LOFAR, ASKAP, MeerKat and SKA will provide larger samples to better address this issue.

Updated Reach of the CERN LHC and Constraints from Relic Density, $b \\to s\\gamma$ and $a_{\\mu}$ in the mSUGRA Model

CERN Document Server

Baer, Howard W; Belyaev, A; Krupovnickas, T; Tata, Xerxes; Baer, Howard; Balazs, Csaba; Belyaev, Alexander; Krupovnickas, Tadas; Tata, Xerxes

2003-01-01

We present an updated assessment of the reach of the CERN LHC pp collider for supersymmetric matter in the context of the minimal supergravity (mSUGRA) model. In addition to previously examined channels, we also include signals with an isolated photon or with a leptonically decaying Z boson. For an integrated luminosity of 100 fb-1, values of m_{1/2}\\sim 1400 GeV can be probed for small m_0, corresponding to a gluino mass of m_{\\tg}\\sim 3 TeV. For large m_0, in the hyperbolic branch/focus point region, m_{1/2}\\sim 700 GeV can be probed, corresponding to m_{\\tg}\\sim 1800 GeV. We also map out parameter space regions preferred by the measured values of the dark matter relic density, the b\\to s\\gamma decay rate, and the muon anomalous magnetic moment a_\\mu, and discuss how SUSY might reveal itself in these regions.

“The Godly Greedy Appetite”: New Relic Circulation in the Early Modern World

Directory of Open Access Journals (Sweden)

Igor Pérez Tostado

2017-05-01

Full Text Available Having lost all monasteries and a good deal of its medieval Christian movable assets, England became one of the greatest producers of new Catholic relics during the sixteenth and seventeenth centuries. This article aims to look, from a material point of view, at the circulation and consumption of English relics on the Catholic continent. In this case, these products were created because of violence and circulated as an answer to it. Gifts and the exchange of relics served to obtain support for the exiled Catholics and for the institutions providing for their education created in the continent, and allowed them to participate in the necropolitics of the Spanish Monarchy. Relics, artifacts and printed and manuscript narratives brought back from all over the world helped construct a selfimage of an English Catholic as a necrocommunity imbued by a sense of historical continuity and connected to a global imagined community.

Discussion of impact of relics activation on protection and utilization approaches-take the old summer palace as an example

Science.gov (United States)

Xiaoqi, J.

2015-08-01

As the popularization of cultural relics and the rapid development of cultural tourism industry, a large number of cultural relic tourism resources goes into public eyes. Activation of relics has became an important way for tourist to contact and understand culture relics. The way of how to properly interpret the historical sense and cultural uniqueness to the masses of tourists in order to achieve social service functions of relic resources has always been research focal point of site protection and utilization, so nowadays it has important significance to protection and utilization of heritage resources in our country. From the point of activation of relics and based on the analysis of resource characteristic, the paper in depth discuss ways of activation of relics of the Old Summer Palace, in order to provide reference for sustainable development of sites tourism in China.

Density dependence of reactor performance with thermal confinement scalings

International Nuclear Information System (INIS)

Stotler, D.P.

1992-03-01

Energy confinement scalings for the thermal component of the plasma published thus far have a different dependence on plasma density and input power than do scalings for the total plasma energy. With such thermal scalings, reactor performance (measured by Q, the ratio of the fusion power to the sum of the ohmic and auxiliary input powers) worsens with increasing density. This dependence is the opposite of that found using scalings based on the total plasma energy, indicating that reactor operation concepts may need to be altered if this density dependence is confirmed in future research

Metal hydrides based high energy density thermal battery

International Nuclear Information System (INIS)

Fang, Zhigang Zak; Zhou, Chengshang; Fan, Peng; Udell, Kent S.; Bowman, Robert C.; Vajo, John J.; Purewal, Justin J.; Kekelia, Bidzina

2015-01-01

Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH 2 and TiMnV as a working pair. • High energy density can be achieved by the use of MgH 2 to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH 2 as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV 0.62 Mn 1.5 alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles

Neutrino Coannihilation on Dark-Matter Relics?

Energy Technology Data Exchange (ETDEWEB)

Barenboim, Gabriela; /Valencia U.; Mena Requejo, Olga; Quigg, Chris; /Fermilab

2006-04-01

High-energy neutrinos may resonate with relic background neutralinos to form short-lived sneutrinos. In some circumstances, the decay chain that leads back to the lightest supersymmetric particle would yield few-GeV gamma rays or charged-particle signals. Although resonant coannihilation would occur at an appreciable rate in our galaxy, the signal in any foreseeable detector is unobservably small.

Metal hydrides based high energy density thermal battery

Energy Technology Data Exchange (ETDEWEB)

Fang, Zhigang Zak, E-mail: zak.fang@utah.edu [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Zhou, Chengshang; Fan, Peng [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Udell, Kent S. [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States); Bowman, Robert C. [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Vajo, John J.; Purewal, Justin J. [HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, CA 90265 (United States); Kekelia, Bidzina [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States)

2015-10-05

Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH{sub 2} and TiMnV as a working pair. • High energy density can be achieved by the use of MgH{sub 2} to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH{sub 2} as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV{sub 0.62}Mn{sub 1.5} alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles.

Mapping the ecological dimensions and potential distributions of endangered relic shrubs in western Ordos biodiversity center.

Science.gov (United States)

Zhu, Geng-Ping; Li, Hui-Qi; Zhao, Li; Man, Liang; Liu, Qiang

2016-05-20

Potential distributions of endemic relic shrubs in western Ordos were poorly mapped, which hindered our implementation of proper conservation. Here we investigated the applicability of ecological niche modeling for endangered relic shrubs to detect areas of priority for biodiversity conservation and analyze differences in ecological niche spaces used by relic shrubs. We applied ordination and niche modeling techniques to assess main environmental drivers of five endemic relic shrubs in western Ordos, namely, Ammopiptanthus mongolicus, Amygdalus mongolica, Helianthemum songaricum, Potaninia mongolica, and Tetraena mongolica. We calculated niche overlap metrics in gridded environmental spaces and compared geographical projections of ecological niches to determine similarities and differences of niches occupied by relic shrubs. All studied taxa presented different responses to environmental factors, which resulted in a unique combination of niche conditions. Precipitation availability and soil quality characteristics play important roles in the distributions of most shrubs. Each relic shrub is constrained by a unique set of environmental conditions, the distribution of one species cannot be implied by the distribution of another, highlighting the inadequacy of one-fits-all type of conservation measure. Our stacked habitat suitability maps revealed regions around Yellow River, which are highly suitable for most species, thereby providing high conservation value.

MULTI-FREQUENCY STUDIES OF RADIO RELICS IN THE GALAXY CLUSTERS A4038, A1664, AND A786

Energy Technology Data Exchange (ETDEWEB)

Kale, Ruta; Dwarakanath, K. S., E-mail: ruta@iucaa.ernet.in [Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080 (India)

2012-01-01

We present a multi-frequency study of radio relics associated with the galaxy clusters A4038, A1664, and A786. Radio images, integrated spectra, spectral index maps, and fits to the integrated spectra in the framework of the adiabatic compression model are presented. Images of the relic in A4038 at 150, 240, and 606 MHz with the Giant Meterwave Radio Telescope have revealed extended ultra-steep spectrum ({alpha} {approx} -1.8 to -2.7) emission of extent 210 Multiplication-Sign 80 kpc{sup 2}. The model of passively evolving radio lobes compressed by a shock fits the integrated spectrum best. The relic with a circular morphology at the outskirts of the cluster A1664 has an integrated spectral index of {approx} - 1.10 {+-} 0.06 and is best fit by the model of radio lobes lurking for {approx}4 Multiplication-Sign 10{sup 7} yr. The relic near A786 has a curved spectrum and is best fit by a model of radio lobes lurking for {approx}3 Multiplication-Sign 10{sup 7} yr. At 4.7 GHz, a compact radio source, possibly the progenitor of the A786 relic, is detected near the center of the radio relic. The A786 radio relic is thus likely a lurking radio galaxy rather than a site of cosmological shock as has been considered in earlier studies.

Dark matter searches from the galaxy to the LHC - recent hints and coming progress

CERN Multimedia

CERN. Geneva

2008-01-01

We discuss the possible galactic positron excess and constraints on interpreting it as dark matter annihilation. We consider wino and higgsino wimps that provide the local relic density and a positron excess (which implies the relic density is non-thermal in origin and important consequences for cosmological history and underlying theories), comment on how to confirm and study these issues at LHC, and on the relation to direct detection experiments.

The heat current density correlation function: sum rules and thermal conductivity

International Nuclear Information System (INIS)

Singh, Shaminder; Tankeshwar, K; Pathak, K N; Ranganathan, S

2006-01-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed

The heat current density correlation function: sum rules and thermal conductivity

Energy Technology Data Exchange (ETDEWEB)

Singh, Shaminder [Department of Physics, Panjab University, Chandigarh-160 014 (India); Tankeshwar, K [Department of Physics, Panjab University, Chandigarh-160 014 (India); Pathak, K N [Department of Physics, Panjab University, Chandigarh-160 014 (India); Ranganathan, S [Department of Physics, Royal Military College, Kingston, ON, K7K 7B4 (Canada)

2006-02-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed.

Higgs portals for thermal Dark Matter. EFT perspectives and the NMSSM

Energy Technology Data Exchange (ETDEWEB)

Baum, Sebastian; Carena, Marcela; Shah, Nausheen R.; Wagner, Carlos E. M.

2018-04-01

We analyze a low energy effective model of Dark Matter in which the thermal relic density is provided by a singlet Majorana fermion which interacts with the Higgs fields via higher dimensional operators. Direct detection signatures may be reduced if blind spot solutions exist, which naturally appear in models with extended Higgs sectors. Explicit mass terms for the Majorana fermion can be forbidden by a $Z_3$ symmetry, which in addition leads to a reduction of the number of higher dimensional operators. Moreover, a weak scale mass for the Majorana fermion is naturally obtained from the vacuum expectation value of a scalar singlet field. The proper relic density may be obtained by the $s$-channel interchange of Higgs and gauge bosons, with the longitudinal mode of the $Z$ boson (the neutral Goldstone mode) playing a relevant role in the annihilation process. This model shares many properties with the Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with light singlinos and heavy scalar and gauge superpartners. In order to test the validity of the low energy effective field theory, we compare its predictions with those of the ultraviolet complete NMSSM. Extending our framework to include $Z_3$ neutral Majorana fermions, analogous to the bino in the NMSSM, we find the appearance of a new bino-singlino well tempered Dark Matter region.

Higgs portals for thermal Dark Matter. EFT perspectives and the NMSSM

Science.gov (United States)

Baum, Sebastian; Carena, Marcela; Shah, Nausheen R.; Wagner, Carlos E. M.

2018-04-01

We analyze a low energy effective model of Dark Matter in which the thermal relic density is provided by a singlet Majorana fermion which interacts with the Higgs fields via higher dimensional operators. Direct detection signatures may be reduced if blind spot solutions exist, which naturally appear in models with extended Higgs sectors. Explicit mass terms for the Majorana fermion can be forbidden by a Z 3 symmetry, which in addition leads to a reduction of the number of higher dimensional operators. Moreover, a weak scale mass for the Majorana fermion is naturally obtained from the vacuum expectation value of a scalar singlet field. The proper relic density may be obtained by the s-channel interchange of Higgs and gauge bosons, with the longitudinal mode of the Z boson (the neutral Goldstone mode) playing a relevant role in the annihilation process. This model shares many properties with the Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with light singlinos and heavy scalar and gauge superpartners. In order to test the validity of the low energy effective field theory, we compare its predictions with those of the ultraviolet complete NMSSM. Extending our framework to include Z 3 neutral Majorana fermions, analogous to the bino in the NMSSM, we find the appearance of a new bino-singlino well tempered Dark Matter region.

arXiv Squeezed relic photons beyond the horizon

CERN Document Server

Giovannini, Massimo

2017-11-14

Owing to the analogy with the ordinary photons in the visible range of the electromagnetic spectrum, the Glauber theory is generalized to address the quantum coherence of the gauge field fluctuations parametrically amplified during an inflationary stage of expansion. The first and second degrees of quantum coherence of relic photons are then computed beyond the effective horizon defined by the evolution of the susceptibility. In the zero-delay limit the Hanbury Brown-Twiss correlations exhibit a super-Poissonian statistics which is however different from the conventional results of the single-mode approximation customarily employed, in quantum optics, to classify the coherence properties of visible light. While in the case of large-scale curvature perturbations the degrees of quantum coherence coincide with the naive expectation of the single-mode approximation, the net degree of second-order coherence computed for the relic photons diminishes thanks to the effect of the polarizations. We suggest that the Han...

Finger of a saint, thumb of a priest: medieval relics in the Diocese of Turku, and the archaeology of lived bodies

Directory of Open Access Journals (Sweden)

Visa Immonen

2011-01-01

Full Text Available The relics of Turku Cathedral are remains belonging to the bodies of holy persons, different from ours, even today, although the cathedral is the see for the archbishop of the Evangelical Lutheran Church of Finland, and relics are not on public display. Among the relics of the cathedral, there is a fragment of a radius, which according to its authentica, belongs to St Henry. Relics and reliquaries were in the core of medieval piety, and the cult of saints had infused throughout the society. Due to their central position in culture, relics offer glimpses at a range of material, social and cultural phenomena related to medieval embodiment.The Department of Archaeology at the University of Turku began to study the finger relic of St Eric and other items in the assemblage of Turku Cathedral in 2007. Relics and reliquaries are being opened and documented and organic as well as inorganic samples are being taken for a range of scientific analyses. So far the project has concentrated on building a chronological chart of individual artefacts. The majority of the relics date to the fourteenth century, although much more recent datings have also been obtained. The challenge of the project is not to stop when a better understanding of materials, their origins and age has been accomplished, but to use the results as a steppingstone into a study of the practices of medieval relic veneration. Medieval bodies and those material processes which authenticate relics, or distinguish saints’ bodies from other human remains, are thus at the heart of this article discussing embodiment.

arXiv Exponentially Light Dark Matter from Coannihilation

CERN Document Server

D'Agnolo, Raffaele Tito; Ruderman, Joshua T.; Wang, Po-Jen

Dark matter may be a thermal relic whose abundance is set by mutual annihilations among multiple species. Traditionally, this coannihilation scenario has been applied to weak scale dark matter that is highly degenerate with other states. We show that coannihilation among states with split masses points to dark matter that is exponentially lighter than the weak scale, down to the keV scale. We highlight the regime where dark matter does not participate in the annihilations that dilute its number density. In this "sterile coannihilation" limit, the dark matter relic density is independent of its couplings, implying a broad parameter space of thermal relic targets for future experiments. Light dark matter from coannihilation evades stringent bounds from the cosmic microwave background, but will be tested by future direct detection, fixed target, and long-lived particle experiments.

Thermal Condensate Structure and Cosmological Energy Density of the Universe

Directory of Open Access Journals (Sweden)

Antonio Capolupo

2016-01-01

Full Text Available The aim of this paper is to study thermal vacuum condensate for scalar and fermion fields. We analyze the thermal states at the temperature of the cosmic microwave background (CMB and we show that the vacuum expectation value of the energy momentum tensor density of photon fields reproduces the energy density and pressure of the CMB. We perform the computations in the formal framework of the Thermo Field Dynamics. We also consider the case of neutrinos and thermal states at the temperature of the neutrino cosmic background. Consistency with the estimated lower bound of the sum of the active neutrino masses is verified. In the boson sector, nontrivial contribution to the energy of the universe is given by particles of masses of the order of 10−4 eV compatible with the ones of the axion-like particles. The fractal self-similar structure of the thermal radiation is also discussed and related to the coherent structure of the thermal vacuum.

The first observations of wide-band interferometers and the spectra of relic gravitons

CERN Document Server

Giovannini, Massimo

2016-01-01

Stochastic backgrounds of relic gravitons of cosmological origin extend from frequencies of the order of the aHz up to the GHz range. Since the temperature and polarization anisotropies constrain the low frequency normalization of the spectra, in the concordance paradigm the strain amplitude corresponding to the frequency window of wide-band interferometers turns out to be, approximately, nine orders of magnitude smaller than the astounding signal recently reported and attributed to a binary black hole merger. The backgrounds of relic gravitons expected from the early Universe are compared with the stochastic foregrounds stemming from the estimated multiplicity of the astrophysical sources. It is suggested that while the astrophysical foregrounds are likely to dominate between few Hz and 10 kHz, relic gravitons with frequencies exceeding 100 kHz represent a potentially uncontaminated signal for the next generation of high-frequency detectors currently under scrutiny.

Cold dark matter in brane cosmology scenario

International Nuclear Information System (INIS)

Dahab, Eiman Abou El; Khalil, Shaaban

2006-01-01

We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating temperature scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10 2 ) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits

a Method of 3d Measurement and Reconstruction for Cultural Relics in Museums

Science.gov (United States)

Zheng, S.; Zhou, Y.; Huang, R.; Zhou, L.; Xu, X.; Wang, C.

2012-07-01

Three-dimensional measurement and reconstruction during conservation and restoration of cultural relics have become an essential part of a modem museum regular work. Although many kinds of methods including laser scanning, computer vision and close-range photogrammetry have been put forward, but problems still exist, such as contradiction between cost and good result, time and fine effect. Aimed at these problems, this paper proposed a structure-light based method for 3D measurement and reconstruction of cultural relics in museums. Firstly, based on structure-light principle, digitalization hardware has been built and with its help, dense point cloud of cultural relics' surface can be easily acquired. To produce accurate 3D geometry model from point cloud data, multi processing algorithms have been developed and corresponding software has been implemented whose functions include blunder detection and removal, point cloud alignment and merge, 3D mesh construction and simplification. Finally, high-resolution images are captured and the alignment of these images and 3D geometry model is conducted and realistic, accurate 3D model is constructed. Based on such method, a complete system including hardware and software are built. Multi-kinds of cultural relics have been used to test this method and results prove its own feature such as high efficiency, high accuracy, easy operation and so on.

Detecting relic gravitational waves in the CMB: Optimal parameters and their constraints

International Nuclear Information System (INIS)

Zhao, W.; Baskaran, D.

2009-01-01

The prospect of detecting relic gravitational waves, through their imprint in the cosmic microwave background radiation, provides an excellent opportunity to study the very early Universe. In the simplest viable theoretical models the relic gravitational wave background is characterized by two parameters, the tensor-to-scalar ratio r and the tensor spectral index n t . In this paper, we analyze the potential joint constraints on these two parameters, r and n t , using the data from the upcoming cosmic microwave background radiation experiments. Introducing the notion of the best-pivot multipole l t *, we find that at this pivot multipole the parameters r and n t are uncorrelated, and have the smallest variances. We derive the analytical formulas for the best-pivot multipole number l t *, and the variances of the parameters r and n t . We verify these analytical calculations using numerical simulation methods, and find agreement to within 20%. The analytical results provide a simple way to estimate the detection ability for the relic gravitational waves by the future observations of the cosmic microwave background radiation.

Late Quaternary sea level and environmental changes from relic ...

Indian Academy of Sciences (India)

Relic carbonate deposits along the western margin of India occur as dolomite crusts, aragonite sands (pelletal / oolitic) and aragonite-cemented limestones, oyster shells, corals, encrusted coralline algal and foraminiferal-dominated nodules. The petrology and mineralogy of the deposits indicate that except for aragonite ...

Stochastic Background of Relic Scalar Gravitational Waves tuned by Extended Gravity

International Nuclear Information System (INIS)

De Laurentis, Mariafelicia; Capozziello, Salvatore

2009-01-01

A stochastic background of relic gravitational waves is achieved by the so called adiabatically-amplified zero-point fluctuations process derived from early inflation. It provides a distinctive spectrum of relic gravitational waves. In the framework of scalar-tensor gravity, we discuss the scalar modes of gravitational waves and the primordial production of this scalar component which is generated beside tensorial one. Then analyze seven different viable f(R)-gravities towards the Solar System tests and stochastic gravitational waves background. It is demonstrated that seven viable f(R)-gravities under consideration not only satisfy the local tests, but additionally, pass the above PPN-and stochastic gravitational waves bounds for large classes of parameters.

High Density Thermal Energy Storage with Supercritical Fluids

Science.gov (United States)

Ganapathi, Gani B.; Wirz, Richard

2012-01-01

A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

Cold dark matter plus not-so-clumpy dark relics

NARCIS (Netherlands)

Diamanti, R.; Ando, S.; Gariazzo, S.; Mena, O.; Weniger, C.

Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark

Perspectives for Detection of a Higgsino-like Relic Neutralino

CERN Document Server

Bottino, A; Mignola, G; Olechowski, M; Scopel, S

1996-01-01

It has been conjectured by Ambrosanio, Kane, Kribs, Martin and Mrenna (AKM) that the CDF event $p \\bar p \\to e^+ e^- \\gamma \\gamma + missing E_T$ is due to a decay chain involving two neutralino states (the lightest and the next-to-lightest ones). The lightest neutralino ($\\chi_{AKM}$) has been further considered by Kane and Wells as a candidate for cold dark matter. In this paper we examine the properties of relic $\\chi_{AKM}$'s in their full parameter space, and examine the perspectives for detection by comparing theoretical predictions to sensitivities of various experimental searches. We find that for most regions of the parameter space the detectability of a relic $\\chi_{AKM}$ would require quite substantial improvements in current experimental sensitivities. The measurements of neutrino fluxes from the center of the Earth and of an excess of $\\bar{p}/p$ in cosmic rays are shown to offer some favorable perspectives for investigating a region of the the model.

Relic abundance of mass-varying cold dark matter particles

International Nuclear Information System (INIS)

Rosenfeld, Rogerio

2005-01-01

In models of coupled dark energy and dark matter the mass of the dark matter particle depends on the cosmological evolution of the dark energy field. In this Letter we exemplify in a simple model the effects of this mass variation on the relic abundance of cold dark matter

RELIC: a novel dye-bias correction method for Illumina Methylation BeadChip.

Science.gov (United States)

Xu, Zongli; Langie, Sabine A S; De Boever, Patrick; Taylor, Jack A; Niu, Liang

2017-01-03

The Illumina Infinium HumanMethylation450 BeadChip and its successor, Infinium MethylationEPIC BeadChip, have been extensively utilized in epigenome-wide association studies. Both arrays use two fluorescent dyes (Cy3-green/Cy5-red) to measure methylation level at CpG sites. However, performance difference between dyes can result in biased estimates of methylation levels. Here we describe a novel method, called REgression on Logarithm of Internal Control probes (RELIC) to correct for dye bias on whole array by utilizing the intensity values of paired internal control probes that monitor the two color channels. We evaluate the method in several datasets against other widely used dye-bias correction methods. Results on data quality improvement showed that RELIC correction statistically significantly outperforms alternative dye-bias correction methods. We incorporated the method into the R package ENmix, which is freely available from the Bioconductor website ( https://www.bioconductor.org/packages/release/bioc/html/ENmix.html ). RELIC is an efficient and robust method to correct for dye-bias in Illumina Methylation BeadChip data. It outperforms other alternative methods and conveniently implemented in R package ENmix to facilitate DNA methylation studies.

Superpixel segmentation and pigment identification of colored relics based on visible spectral image

Science.gov (United States)

Li, Junfeng; Wan, Xiaoxia

2018-01-01

To enrich the contents of digital archive and to guide the copy and restoration of colored relics, non-invasive methods for extraction of painting boundary and identification of pigment composition are proposed in this study based on the visible spectral images of colored relics. Superpixel concept is applied for the first time to the field of oversegmentation of visible spectral images and implemented on the visible spectral images of colored relics to extract their painting boundary. Since different pigments are characterized by their own spectrum and the same kind of pigment has the similar geometric profile in spectrum, an automatic identification method is established by comparing the proximity between the geometric profiles of the unknown spectrum from each superpixel and the pre-known spectrum from a deliberately prepared database. The methods are validated using the visible spectral images of the ancient wall paintings in Mogao Grottoes. By the way, the visible spectral images are captured by a multispectral imaging system consisting of two broadband filters and a RGB camera with high spatial resolution.

Relic neutrino asymmetry evolution from first principles

International Nuclear Information System (INIS)

Bell, N.F.; Volkas, R.R.; Wong, Y.Y.Y.

1998-09-01

The exact Quantum Kinetic Equations for a two-flavour active-sterile neutrino system are used to provide a systematic derivation of approximate evolution equations for the relic neutrino asymmetry. An extension of the adiabatic approximation for matter-affected neutrino oscillations is developed which incorporates decoherence due to collisions. Exact and approximate expressions for the decoherence and repopulation functions are discussed. A first pass is made over the exact treatment of multi-flavour partially incoherent oscillations. (authors)

Lyman-alpha clouds as a relic of primordial density fluctuations

International Nuclear Information System (INIS)

Bond, J.R.; Szalay, A.S.; Silk, J.

1988-01-01

Primordial density fluctuations are studied using a CDM model and primordial clouds some of which are expanding, driven by pressure gradients created when the medium is photionized, and some of which are massive enough to continue collapsing in spite of the pressure. Normalization of CDM models to the clustering properties on large scales are used to predict the parameters of collapsing clouds of subgalactic mass at early epochs. It is shown that the abundance and dimensions of these clouds are comparable to those of the Lyman-alpha systems. The evolutionary history of the clouds is computed, utilizing a spherically symmetric hydrodynamics code with the dark matter treated as a collisionless fluid, and the H I column density distribution is evaluated as a function of N(H I) and redshift. The observed cloud parameters come out naturally in the CDM model and suggest that Lyman-alpha clouds are the missing link between primordial density fluctuations and the formation of galaxies. 31 references

Quantum state correction of relic gravitons from quantum gravity

OpenAIRE

Rosales, Jose-Luis

1996-01-01

The semiclassical approach to quantum gravity would yield the Schroedinger formalism for the wave function of metric perturbations or gravitons plus quantum gravity correcting terms in pure gravity; thus, in the inflationary scenario, we should expect correcting effects to the relic graviton (Zel'dovich) spectrum of the order (H/mPl)^2.

Thermal Conductivity of Human Bone in Cryoprobe Freezing as Related to Density.

Science.gov (United States)

Walker, Kyle E; Baldini, Todd; Lindeque, Bennie G

2017-03-01

Cryoprobes create localized cell destruction through freezing. Bone is resistant to temperature flow but is susceptible to freezing necrosis at warmer temperatures than tumor cells. Few studies have determined the thermal conductivity of human bone. No studies have examined conductivity as related to density. The study goal was to examine thermal conductivity in human bone while comparing differences between cancellous and cortical bone. An additional goal was to establish a relationship between bone density and thermal conductivity. Six knee joints from 5 cadavers were obtained. The epiphyseal region was sliced in half coronally prior to inserting an argon-circulating cryoprobe directed away from the joint line. Thermistor thermometers were placed perpendicularly at measured increments, and the freezing cycle was recorded until steady-state conditions were achieved. For 2 cortical samples, the probe was placed intramedullary in metaphyseal samples and measurements were performed radially from the central axis of each sample. Conductivity was calculated using Fournier's Law and then plotted against measured density of each sample. Across samples, density of cancellous bone ranged from 0.86 to 1.38 g/mL and average thermal conductivity ranged between 0.404 and 0.55 W/mK. Comparatively, cortical bone had a density of 1.70 to 1.86 g/mL and thermal conductivity of 0.0742 to 0.109 W/mK. A strong 2-degree polynomial correlation was seen (R 2 =0.8226, P<.001). Bone is highly resistant to temperature flow. This resistance varies and inversely correlates strongly with density. This information is clinically relevant to maximize tumor ablation while minimizing morbidity through unnecessary bone loss and damage to surrounding structures. [Orthopedics. 2017; 40(2):90-94.]. Copyright 2016, SLACK Incorporated.

Azobenzene-functionalized carbon nanotubes as high-energy density solar thermal fuels.

Science.gov (United States)

Kolpak, Alexie M; Grossman, Jeffrey C

2011-08-10

Solar thermal fuels, which reversibly store solar energy in molecular bonds, are a tantalizing prospect for clean, renewable, and transportable energy conversion/storage. However, large-scale adoption requires enhanced energy storage capacity and thermal stability. Here we present a novel solar thermal fuel, composed of azobenzene-functionalized carbon nanotubes, with the volumetric energy density of Li-ion batteries. Our work also demonstrates that the inclusion of nanoscale templates is an effective strategy for design of highly cyclable, thermally stable, and energy-dense solar thermal fuels.

Quintessential inflation on the brane and the relic gravity wave background

International Nuclear Information System (INIS)

Sami, M.; Sahni, V.

2004-01-01

Quintessential inflation describes a scenario in which both inflation and dark energy (quintessence) are described by the same scalar field. In conventional braneworld models of quintessential inflation gravitational particle-production is used to reheat the universe. This reheating mechanism is very inefficient and results in an excessive production of gravity waves which violate nucleosynthesis constraints and invalidate the model. We describe a new method of realizing quintessential inflation on the brane in which inflation is followed by 'instant preheating' (Felder, Kofman and Linde 1999). The larger reheating temperature in this model results in a smaller amplitude of relic gravity waves which is consistent with nucleosynthesis bounds. The relic gravity wave background has a 'blue' spectrum at high frequencies and is a generic byproduct of successful quintessential inflation on the brane

Proto-ribosome: a theoretical approach based on RNA relics

OpenAIRE

Demongeot, Jacques

2017-01-01

We describe in this paper, based on already published articles, a contribution to the theory postulating the existence of a proto-ribosome, which could have appeared early at the origin of life and we discuss the interest of this notion in an evolutionary perspective, taking into account the existence of possible RNA relics of this proto-ribosome.

Similarity of dependences of thermal conductivity and density of uranium and tungsten hexafluorides on desublimation conditions

International Nuclear Information System (INIS)

Barkov, V.A.

1989-01-01

Consideration is given to results of investigations of the dependence of thermal conductivity and density of UF 6 and WF 6 desublimates on volume content of hexafluoride in initial gaseous mixture. Similarity of these dependences, as well as the dependences of thermal conductivity of desublimates on their density was revealed. Generalized expressions, relating thermal conductivity and density of desublimates among each ofter and with volume content of hexafluoride in gaseous mixture were derived. Possibility of applying the generalized relations for calculation of thermal conductivity and density of other compounds of MeF 6 type under prescribed desublimation conclitions is shown. 15 refs.; 6 figs

Effects of thermal inflation on small scale density perturbations

Energy Technology Data Exchange (ETDEWEB)

Hong, Sungwook E. [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Seoul 130-722 (Korea, Republic of); Lee, Hyung-Joo; Lee, Young Jae; Stewart, Ewan D. [Department of Physics, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-338 (Korea, Republic of); Zoe, Heeseung, E-mail: swhong@kias.re.kr, E-mail: ohsk111@kaist.ac.kr, E-mail: noasac@kaist.ac.kr, E-mail: jcap@profstewart.org, E-mail: heezoe@dgist.ac.kr [School of Basic Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno jungang-daero, Daegu 711-873 (Korea, Republic of)

2015-06-01

In cosmological scenarios with thermal inflation, extra eras of moduli matter domination, thermal inflation and flaton matter domination exist between primordial inflation and the radiation domination of Big Bang nucleosynthesis. During these eras, cosmological perturbations on small scales can enter and re-exit the horizon, modifying the power spectrum on those scales. The largest modified scale, k{sub b}, touches the horizon size when the expansion changes from deflation to inflation at the transition from moduli domination to thermal inflation. We analytically calculate the evolution of perturbations from moduli domination through thermal inflation and evaluate the curvature perturbation on the constant radiation density hypersurface at the end of thermal inflation to determine the late time curvature perturbation. Our resulting transfer function suppresses the power spectrum by a factor 0∼ 5 at k >> k{sub b}, with k{sub b} corresponding to anywhere from megaparsec to subparsec scales depending on the parameters of thermal inflation. Thus, thermal inflation might be constrained or detected by small scale observations such as CMB distortions or 21cm hydrogen line observations.

Asymmetric condensed dark matter

Energy Technology Data Exchange (ETDEWEB)

Aguirre, Anthony; Diez-Tejedor, Alberto, E-mail: aguirre@scipp.ucsc.edu, E-mail: alberto.diez@fisica.ugto.mx [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA, 95064 (United States)

2016-04-01

We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate must be lighter than a few tens of eV so that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles.

Dissimilarities of reduced density matrices and eigenstate thermalization hypothesis

Science.gov (United States)

He, Song; Lin, Feng-Li; Zhang, Jia-ju

2017-12-01

We calculate various quantities that characterize the dissimilarity of reduced density matrices for a short interval of length ℓ in a two-dimensional (2D) large central charge conformal field theory (CFT). These quantities include the Rényi entropy, entanglement entropy, relative entropy, Jensen-Shannon divergence, as well as the Schatten 2-norm and 4-norm. We adopt the method of operator product expansion of twist operators, and calculate the short interval expansion of these quantities up to order of ℓ9 for the contributions from the vacuum conformal family. The formal forms of these dissimilarity measures and the derived Fisher information metric from contributions of general operators are also given. As an application of the results, we use these dissimilarity measures to compare the excited and thermal states, and examine the eigenstate thermalization hypothesis (ETH) by showing how they behave in high temperature limit. This would help to understand how ETH in 2D CFT can be defined more precisely. We discuss the possibility that all the dissimilarity measures considered here vanish when comparing the reduced density matrices of an excited state and a generalized Gibbs ensemble thermal state. We also discuss ETH for a microcanonical ensemble thermal state in a 2D large central charge CFT, and find that it is approximately satisfied for a small subsystem and violated for a large subsystem.

Miscibility gap alloys with inverse microstructures and high thermal conductivity for high energy density thermal storage applications

International Nuclear Information System (INIS)

Sugo, Heber; Kisi, Erich; Cuskelly, Dylan

2013-01-01

New high energy-density thermal storage materials are proposed which use miscibility gap binary alloy systems to operate through the latent heat of fusion of one component dispersed in a thermodynamically stable matrix. Using trial systems Al–Sn and Fe–Cu, we demonstrate the development of the required inverse microstructure (low melting point phase embedded in high melting point matrix) and excellent thermal storage potential. Several other candidate systems are discussed. It is argued that such systems offer enhancement over conventional phase change thermal storage by using high thermal conductivity microstructures (50–400 W/m K); minimum volume of storage systems due to high energy density latent heat of fusion materials (0.2–2.2 MJ/L); and technical utility through adaptability to a great variety of end uses. Low (<300 °C), mid (300–400 °C) and high (600–1400 °C) temperature options exist for applications ranging from space heating and process drying to concentrated solar thermal energy conversion and waste heat recovery. -- Highlights: ► Alloys of immiscible metals are proposed as thermal storage systems. ► High latent heat of fusion per unit volume and tunable temperature are advantageous. ► Thermal storage systems with capacities of 0.2–2.2 MJ/L are identified. ► Heat delivery is via a rigid non-reactive high thermal conductivity matrix. ► The required inverse microstructures were developed for Sn–Al and Cu–Fe systems

A novel track density measurement method by thermal neutron activation of DYECETs

International Nuclear Information System (INIS)

Sohrabi, M.; Mahdi, Sh.

1995-01-01

A novel track density evaluation method based on thermal neutron activation of some elements of dyed electrochemically etched tracks (DYECETs) of charged particles in detectors like polycarbonate (PC) followed by measurements of gamma activity of the activated detectors is introduced. In this method, the tracks of charged particles like fast neutron-induced recoils in PC detectors were electrochemically etched, dyed by ''QuicDYECET'' methods as recently introduced by us, activated by thermal neutrons and counted for gamma activity determination to be correlated with track density. The activities of elements such as bromine-82 ( 82 Br) and sodium-24 ( 24 Na) on dyes such as Eosin Yellowish, Eosin Bluish, etc. determined by a hyper-pure germanium detector, were found to be in good correlation with DYECET density and thus particle fluence or dose. The effects of different types of dyes and their elements, dye concentration, neutron fluences and ECE durations on the DYECET density responses were studied. This new development is a method of scientific interest, potentially possessing some interesting features, as an alternative method for ECE track density determination using a gamma activity measuring system. It also has the drawback of being applicable only in centres having thermal neutron facilities. The results of the above studies are presented and discussed. (Author)

The Smell of Relics: Authenticating Saintly Bones and the Role of Scent in the Sensory Experience of Medieval Christian Veneration

Directory of Open Access Journals (Sweden)

Paul Anthony Brazinski

2013-09-01

Full Text Available ''The archaeology of smell is a burgeoning field in recent scholarship. This paper adds to existing literature by investigating the function of smell in relation to relic sales and veneration in medieval Europe, a hitherto understudied area of research. Collating historical texts concerning the translatio of saintly relics in Western Europe and the Byzantine Empire with archaeological sources associated with relic veneration and religious worship (including ampullae, unguentaria, sarcophagi, holy oils, pillow graves, and silk, this paper suggests that (1 smell was used in the medieval world as a means to challenge or confirm a relic’s authenticity, and (2 olfactory liquids that imbued or permeated material objects in the context of worship functioned as a means of focusing attention on relic veneration and were an essential part of the cult and/or pilgrimage experience.

Constraints upon the spectral indices of relic gravitational waves by LIGO S5

International Nuclear Information System (INIS)

Zhang, Y.; Tong, M. L.; Fu, Z. W.

2010-01-01

With LIGO having achieved its design sensitivity and the LIGO S5 strain data being available, constraints on the relic gravitational waves (RGWs) become realistic. The analytical spectrum of RGWs generated during inflation depends sensitively on the initial condition, which is generically described by the index β, the running index α t , and the tensor-to-scalar ratio r. By the LIGO S5 data of the cross-correlated two detectors, we obtain constraints on the parameters (β,α t ,r). As a main result, we have computed the theoretical signal-to-noise ratio of RGWs for various values of (β,α t ,r), using the cross-correlation for the given pair of LIGO detectors. The constraints by the indirect bound on the energy density of RGWs by big bang nucleosynthesis and cosmic microwave background have been obtained, which turn out to be still more stringent than LIGO S5.

Update of axion CDM energy density

International Nuclear Information System (INIS)

Huh, Ji-Haeng

2008-01-01

We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale Λ QCD , the current quark masses m q 's and the Peccei-Quinn scale F a , including firstly introduced 1.85 factor which is from the initial overshoot.

Influence of thermal buoyancy on vertical tube bundle thermal density head predictions under transient conditions

International Nuclear Information System (INIS)

Lin, H.C.; Kasza, K.E.

1984-01-01

The thermal-hydraulic behavior of an LMFBR system under various types of plant transients is usually studied using one-dimensional (1-D) flow and energy transport models of the system components. Many of the transient events involve the change from a high to a low flow with an accompanying change in temperature of the fluid passing through the components which can be conductive to significant thermal bouyancy forces. Thermal bouyancy can exert its influence on system dynamic energy transport predictions through alterations of flow and thermal distributions which in turn can influence decay heat removal, system-response time constants, heat transport between primary and secondary systems, and thermal energy rejection at the reactor heat sink, i.e., the steam generator. In this paper the results from a comparison of a 1-D model prediction and experimental data for vertical tube bundle overall thermal density head and outlet temperature under transient conditions causing varying degrees of thermal bouyancy are presented. These comparisons are being used to generate insight into how, when, and to what degree thermal buoyancy can cause departures from 1-D model predictions

Relics of the cosmological quark-hadron phase transition

International Nuclear Information System (INIS)

Sinha, Bikash

2001-01-01

In this talk I will not dwell further on the nature of the Q -> H transition, Instead, I will simply assume that it is a phase transition, and further, a first-order phase transition, in which case, there is a possibility that a particular kind of relics called quark nuggets (QNs) containing a large fraction of the net baryon number of the universe may have been formed at the end of such a phase transition. The QNs would have tremendous implications for cosmology and astrophysics. In particular, they can be a good candidate for the baryonic dark matter in the universe provided they can survive up to the present epoch. The QNs which survived and floating around the universe, is there any connection with the recently discovered MACHOs between the earth and the Large Magellanic clouds. The QNs are hypothesized to be made of 'strange matter' which is composed of a roughly equal mixture of u, d, and s quarks at a density ≥ nuclear density. It has been hypothesized that at zero temperature and zero pressure the true ground state of hadronic matter could be SM rather than 56 Fe, the energy per baryon in SM could be lower that in ordinary nuclear matter. The latter would, however, still be effectively stable against decay would require high order simultaneous weak interaction process with a life-time much greater than the age of the universe. For certain ranges of values of parameters involved, namely, the QCD fine structure constant (α c ), mass of the strange quark (m s ), the vacuum bag energy (B), the hypothesis of SM being the absolutely stable of hadronic matter has been found to be quite plausible. (author)

Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

Science.gov (United States)

Koca, H. D.; Evgin, T.; Horny, N.; Chirtoc, M.; Turgut, A.; Tavman, I. H.

2017-12-01

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

Influence of polypropylene fibres on the tensile strength and thermal properties of various densities of foamed concrete

Science.gov (United States)

Jhatial, Ashfaque Ahmed; Inn, Goh Wan; Mohamad, Noridah; Johnson Alengaram, U.; Mo, Kim Hung; Abdullah, Redzuan

2017-11-01

As almost half of the world’s population now lives in the urban areas, the raise in temperature in these areas has necessitated the development of thermal insulating material. Conventional concrete absorbs solar radiation during the daytime while releasing it at night causing raise in temperature in urban areas. The thermal conductivity of 2200 kg/m3 density conventional concrete is 1.6 W/mK. Higher the thermal conductivity value, greater the heat flow through the material. To reduce this heat transfer, the construction industry has turned to lightweight foamed concrete. Foamed concrete, due to its air voids, gives excellent thermal properties and sound absorption apart from fire-resistance and self-leveling properties. But due to limited studies on different densities of foamed concrete, the thermal properties are not understood properly thus limiting its use as thermal insulating material. In this study, thermal conductivity is determined for 1400, 1600 and 1800 kg/m3 densities of foamed concrete. 0.8% of Polypropylene fibres (PP) is used to reinforce the foamed concrete and improve the mechanical properties. Based upon the results, it was found that addition of PP fibres enhances the tensile strength and slightly reduced the thermal conductivity for lower densities, while the reverse affect was noticed in 1800 kg/m3 density.

Computing thermal Wigner densities with the phase integration method

International Nuclear Information System (INIS)

Beutier, J.; Borgis, D.; Vuilleumier, R.; Bonella, S.

2014-01-01

We discuss how the Phase Integration Method (PIM), recently developed to compute symmetrized time correlation functions [M. Monteferrante, S. Bonella, and G. Ciccotti, Mol. Phys. 109, 3015 (2011)], can be adapted to sampling/generating the thermal Wigner density, a key ingredient, for example, in many approximate schemes for simulating quantum time dependent properties. PIM combines a path integral representation of the density with a cumulant expansion to represent the Wigner function in a form calculable via existing Monte Carlo algorithms for sampling noisy probability densities. The method is able to capture highly non-classical effects such as correlation among the momenta and coordinates parts of the density, or correlations among the momenta themselves. By using alternatives to cumulants, it can also indicate the presence of negative parts of the Wigner density. Both properties are demonstrated by comparing PIM results to those of reference quantum calculations on a set of model problems

Computing thermal Wigner densities with the phase integration method.

Science.gov (United States)

Beutier, J; Borgis, D; Vuilleumier, R; Bonella, S

2014-08-28

We discuss how the Phase Integration Method (PIM), recently developed to compute symmetrized time correlation functions [M. Monteferrante, S. Bonella, and G. Ciccotti, Mol. Phys. 109, 3015 (2011)], can be adapted to sampling/generating the thermal Wigner density, a key ingredient, for example, in many approximate schemes for simulating quantum time dependent properties. PIM combines a path integral representation of the density with a cumulant expansion to represent the Wigner function in a form calculable via existing Monte Carlo algorithms for sampling noisy probability densities. The method is able to capture highly non-classical effects such as correlation among the momenta and coordinates parts of the density, or correlations among the momenta themselves. By using alternatives to cumulants, it can also indicate the presence of negative parts of the Wigner density. Both properties are demonstrated by comparing PIM results to those of reference quantum calculations on a set of model problems.

Computational Design of Non-natural Sugar Alcohols to Increase Thermal Storage Density: Beyond Existing Organic Phase Change Materials.

Science.gov (United States)

Inagaki, Taichi; Ishida, Toyokazu

2016-09-14

Thermal storage, a technology that enables us to control thermal energy, makes it possible to reuse a huge amount of waste heat, and materials with the ability to treat larger thermal energy are in high demand for energy-saving societies. Sugar alcohols are now one promising candidate for phase change materials (PCMs) because of their large thermal storage density. In this study, we computationally design experimentally unknown non-natural sugar alcohols and predict their thermal storage density as a basic step toward the development of new high performance PCMs. The non-natural sugar alcohol molecules are constructed in silico in accordance with the previously suggested molecular design guidelines: linear elongation of a carbon backbone, separated distribution of OH groups, and even numbers of carbon atoms. Their crystal structures are then predicted using the random search method and first-principles calculations. Our molecular simulation results clearly demonstrate that the non-natural sugar alcohols have potential ability to have thermal storage density up to ∼450-500 kJ/kg, which is significantly larger than the maximum thermal storage density of the present known organic PCMs (∼350 kJ/kg). This computational study suggests that, even in the case of H-bonded molecular crystals where the electrostatic energy contributes mainly to thermal storage density, the molecular distortion and van der Waals energies are also important factors to increase thermal storage density. In addition, the comparison between the three eight-carbon non-natural sugar alcohol isomers indicates that the selection of preferable isomers is also essential for large thermal storage density.

Non Thermal Emission from Clusters of Galaxies: the Importance of a Joint LOFAR/Simbol-X View

Science.gov (United States)

Ferrari, C.

2009-05-01

Deep radio observations of galaxy clusters have revealed the existence of diffuse radio sources (``halos'' and ``relics'') related to the presence of relativistic electrons and weak magnetic fields in the intracluster volume. I will outline our current knowledge about the presence and properties of this non-thermal cluster component. Despite the recent progress made in observational and theoretical studies of the non-thermal emission in galaxy clusters, a number of open questions about its origin and its effects on the thermo-dynamical evolution of galaxy clusters need to be answered. I will show the importance of combining galaxy cluster observations by new-generation instruments such as LOFAR and Simbol-X. A deeper knowledge of the non-thermal cluster component, together with statistical studies of radio halos and relics, will allow to test the current cluster formation scenario and to better constrain the physics of large scale structure evolution.

Non Thermal Emission from Clusters of Galaxies: the Importance of a Joint LOFAR/Simbol-X View

International Nuclear Information System (INIS)

Ferrari, C.

2009-01-01

Deep radio observations of galaxy clusters have revealed the existence of diffuse radio sources ('halos' and 'relics') related to the presence of relativistic electrons and weak magnetic fields in the intracluster volume. I will outline our current knowledge about the presence and properties of this non-thermal cluster component. Despite the recent progress made in observational and theoretical studies of the non-thermal emission in galaxy clusters, a number of open questions about its origin and its effects on the thermo-dynamical evolution of galaxy clusters need to be answered. I will show the importance of combining galaxy cluster observations by new-generation instruments such as LOFAR and Simbol-X. A deeper knowledge of the non-thermal cluster component, together with statistical studies of radio halos and relics, will allow to test the current cluster formation scenario and to better constrain the physics of large scale structure evolution.

Ultra-cold WIMPs relics of non-standard pre-BBN cosmologies

CERN Document Server

Gelmini, Graciela B

2008-01-01

We point out that in scenarios in which the Universe evolves in a non-standard manner during and after the kinetic decoupling of weakly interacting massive particles (WIMPs), these relics can be much colder than in standard cosmological scenarios (i.e. can be ultra-cold), possibly leading to the formation of smaller first objects in hierarchical structure formation scenarios.

Dusty Relic to Shining Treasure: Embedded in a Multicultural Environment

Science.gov (United States)

Avery, Beth Fuseler; Batman, Cindy

2014-01-01

Far from being dusty old relics who are guardians of the book, embedded librarians need to be proactively leading students through the digital maze of the virtual library. Working with students more than 7,000 miles away changed perceptions of how to teach and learn, and how people interact online. We will share how as embedded librarians we…

Effect of gamma irradiation on density and thermal expansion changes of uniaxial oriented LLDPE

International Nuclear Information System (INIS)

Kacarevic-Popovic, Z.; Kostoski, D.; Novakovic, Lj.

1998-01-01

Complete text of publication follows. It is well known that gamma irradiation induces cross-linking in the amorphous phase of isotropic polyethylene, or chain scission in highly oriented fibers and films. Thermomechanical behavior and values of density are the reflection of the changes induced by gamma irradiation. Namely, scission of macromolecules, in general, increases thermal expansion coefficient and decreases density and vice versa. On the other hand, as it is well known, the thermal expansion behavior of oriented polymers shows marked anisotropy. It was found that many highly oriented polymers show a negative coefficient of thermal expansion in the draw direction and a positive coefficient in the transverse direction. It has been suggested that, apart from any intrinsic crystalline contribution, a significant part of the negative thermal expansion coefficients obtained for highly oriented polymers arises from the effect of entropy internal stresses in the amorphous regions. From our previous work, the thermal coefficients in draw direction of irradiated samples rise in the glass transition temperature range and it was related to the effects of cross-linking in the amorphous phase of LDPE. In our present work we observed initial decrease in density with absorbed dose, up to 35 kGy, and subsequent increase up to a dose of 500 kGy. The observed increase in thermal expansion coefficient followed the changes in density and is related to the parallel processes of chain scission and net cross-linking in the amorphous phase of LLDPE, induced by gamma irradiation

Supersymmetry, Dark Matter and the LHC

International Nuclear Information System (INIS)

Tata, Xerxes

2010-01-01

The conceptually simplest scenario for dark matter (DM) is that it is a stable thermal relic from standard Big Bang cosmology, in many SUSY models the lightest neutralino. The relic density determination selects special regions in SUSY model parameter space with concomitant implications for collider physics, dark matter searches and low energy measurements. By studying various one-parameter extensions of the much-studied mSUGRA model (where we relax the untested universality assumptions) constructed to be in accord with the measured relic density, we show that these implications are in general model-dependent, so that LHC and DM measurements will provide clues to how sparticles acquire their masses. We point out some relatively robust implications for LHC and DM searches and conclude with an outlook for the future.

The Shroud of Turin: Relic or icon?

International Nuclear Information System (INIS)

Dale, W.S.A.

1987-01-01

The Shroud of Turin, a linen cloth on which appear the imprints of the front and back of a crucified man, can be historically traced to ca. 1354 A.D. Many believe it to be a true relic of the Passion of Christ. Many others regard it as a fake. This paper suggests a third alternative, that it is an icon dating from the 11th century. If future scientific tests, of which radiocarbon dating will be the most important, support this theory, the Shroud of Turin may well be recognized as one of the masterpieces of Christian art. (orig.)

T-junction cross-flow mixing with thermally driven density stratification

Energy Technology Data Exchange (ETDEWEB)

Kickhofel, John, E-mail: jkickhofel@gmail.com [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Selvam, P. Karthick, E-mail: karthick.selvam@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Laurien, Eckart, E-mail: eckart.laurien@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Kulenovic, Rudi, E-mail: rudi.kulenovic@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

2016-12-01

Highlights: • Mesh sensor for realistic nuclear thermal hydraulic scenarios is demonstrated. • Flow temperature behavior across a wide range of Richardson numbers measured. • Upstream stratified flow in the T-junction results in a thermal shock scenario. • Large, stable near-wall thermal gradients exist in spite of turbulent flows. - Abstract: As a means of further elucidating turbulence- and stratification-driven thermal fatigue in the vicinity of T-junctions in nuclear power plants, a series of experiments have been conducted at the high temperature high pressure fluid–structure interaction T-junction facility of the University of Stuttgart with novel fluid measurement instrumentation. T-junction mixing with large fluid temperature gradients results in complex flow behavior, the result of density driven effects. Deionized water mixing at temperature differences of up to 232 K at 7 MPa pressure have been investigated in a T-junction with main pipe diameter 71.8 mm and branch line diameter 38.9 mm. The experiments have been performed with fixed flow rates of 0.4 kg/s in the main pipe and 0.1 kg/s in the branch line. A novel electrode-mesh sensor compatible with the DN80 PN100 pipeline upstream and downstream of the T-junction has been utilized as a temperature sensor providing a high density information in the pipe cross-section in both space and time. Additionally, in-flow and in-wall thermocouples quantify the damping of thermal fluctuations by the wall material. The results indicate that large inflow temperature differences lead to strong turbulence damping, and ultimately stable stratification extending both downstream and upstream of the T-junction resulting in large local thermal gradients.

Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

Science.gov (United States)

Johnson, Wesley L.

2011-01-01

Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

Cosmological constraints on the amplitude of relic gravitational waves

International Nuclear Information System (INIS)

Novosyadlij, B.; Apunevich, S.

2005-01-01

The evolution of the amplitude of relic gravitational waves (RGW) generated in early Universe has been analyzed. The analytical approximation is presented for angular power spectrum of cosmic microwave background anisotropies caused by gravitational waves through Sachs-Wolfe effect. The estimate of the most probable value for this amplitude was obtained on the basis of observation data on cosmic microwave background anisotropies from COBE, WMAP and BOOMERanG experiments along with large-scale structure observations

The long-lived stau as a thermal relic

Energy Technology Data Exchange (ETDEWEB)

Pradler, Josef

2009-07-20

We consider physics beyond the Standard Model which implies the existence a of long-lived electromagnetically charged massive particle species (CHAMP) which we denote by X{sup {+-}}. We discuss in detail the unique sensitivity the early Universe exhibits on the mere presence and on the decay of such a particle. We carry out a detailed study of gravitino (G) dark matter scenarios in which the lighter scalar tau (stau, {tau}{sub 1}) is the lightest Standard Model superpartner so that {tau}{sub 1}=X. We also provide a thorough investigation of the thermal freeze-out process of {tau}{sub 1}. The thesis is divided into three parts: Part I: In this part we consider a generic but weak-scale CHAMP. In Chapter 1 we set the stage for the coming investigations by shortly reviewing the framework of Big Bang Nucleosynthesis (BBN), by working out the typical CHAMP freeze-out abundance, and by reviewing the stringent constraints arising from such a decaying component during/after BBN. In Chapter 2 we discuss the physics which emerges when the light elements fused in BBN are captured by X{sup -} at the time of primordial nucleosynthesis. In the remainder of this chapter we focus on the catalytic production of {sup 6}Li and {sup 9}Be. The second part is devoted to scenarios in which G is the lightest supersymmetric particle (LSP) and {tau}{sub 1} is the next-to-lightest SUSY particle (NLSP). In Chapter 3 we focus on the gravitino LSP as a dark matter candidate. In Chapter 4 we then focus on gravitino dark matter scenarios in which {tau}{sub 1} is the NLSP. In Part III we take an in-depth look into the chemical decoupling process of the long-lived {tau}{sub 1} from the primordial plasma. The quantity of interest is the thermal freeze-out abundance of the stau. We identify its dependence on the crucial SUSY parameters and also show that it sensitively depends on the details of the Higgs sector. Stau annihilation into final state Higgses as well as resonant annihilation via the heavy

Thermal Cracking of Low Density Polyethylene (LDPE) Waste into ...

African Journals Online (AJOL)

Waste low density polyethylene film (table water sachets) was converted into solid, liquid oil and gaseous products by thermal process in a self- designed stainless steel laboratory reactor. The waste polymer was completely pyrolized within the temperature range of 474 – 520°C and 2hours reaction time. The solid residue ...

Non-thermal production of minimal dark matter via right-handed neutrino decay

International Nuclear Information System (INIS)

Aoki, Mayumi; Toma, Takashi; Vicente, Avelino

2015-01-01

Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above O(10) TeV in order to reproduce the observed dark matter relic density. Motivated by this little drawback, in this paper we consider an extension of the MDM scenario by three right-handed neutrinos. Two specific choices for the MDM multiplet are studied: a fermionic SU(2) L quintuplet and a scalar SU(2) L septuplet. The lightest right-handed neutrino, with tiny Yukawa couplings, never reaches thermal equilibrium in the early universe and is produced by freeze-in. This creates a link between dark matter and neutrino physics: dark matter can be non-thermally produced by the decay of the lightest right-handed neutrino after freeze-out, allowing to lower significantly the dark matter mass. We discuss the phenomenology of the non-thermally produced MDM and, taking into account significant Sommerfeld corrections, we find that the dark matter mass must have some specific values in order not to be in conflict with the current bounds from gamma-ray observations

Advances in research on protection of stone relics by science and technology methods%石质文物科技保护研究进展

Institute of Scientific and Technical Information of China (English)

叶良; 李强强; 孙平平

2016-01-01

总结了石质文物病害机理研究及病害检测技术、石质文物清洗方法、石质文物保护材料、石质文物监测方法、现代化信息技术，在石质文物科技保护中的应用等方面的研究现状和取得的重要成就，并针对石质文物科技保护在保护材料、仪器设备等方面现存的问题提出了一些建议。%This paper summarized research situation and great achievements obtained in stone cultural relics disease mechanism research and disease detection technology ,stone cultural relics cleaning method ,materials for stone cultural relics conservation ,stone cultural relics monitoring method ,the application of modern information technology in stone cultural relics protection . Based on that ,some suggestions are put forward for the problems existed in protection of stone relics by science and technology methods in protective materials ,equipment and other aspects .

Interfacial thermal resistance between high-density polyethylene (HDPE) and sapphire

International Nuclear Information System (INIS)

Zheng Kun; Ma Yong-Mei; Wang Fo-Song; Zhu Jie; Tang Da-Wei

2014-01-01

To improve the thermal conductivity of polymeric composites, the numerous interfacial thermal resistance (ITR) inside is usually considered as a bottle neck, but the direct measurement of the ITR is hardly reported. In this paper, a sandwich structure which consists of transducer/high density polyethylene (HDPE)/sapphire is prepared to study the interface characteristics. Then, the ITRs between HDPE and sapphire of two samples with different HDPE thickness values are measured by time-domain thermoreflectance (TDTR) method and the results are ∼ 2 × 10 −7 m 2 ·K·W −1 . Furthermore, a model is used to evaluate the importance of ITR for the thermal conductivity of composites. The model's analysis indicates that reducing the ITR is an effective way of improving the thermal conductivity of composites. These results will provide valuable guidance for the design and manufacture of polymer-based thermally conductive materials. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Chemically and Thermally Stable High Energy Density Silicone Composites, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Thermal energy storage systems with 300 -- 1000 kJ/kg energy density through either phase changes or chemical heat absorption are sought by NASA. This proposed...

NGC 1277: A MASSIVE COMPACT RELIC GALAXY IN THE NEARBY UNIVERSE

Energy Technology Data Exchange (ETDEWEB)

Trujillo, Ignacio; Vazdekis, Alexandre [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205-La Laguna, Tenerife (Spain); Ferré-Mateu, Anna [Subaru Telescope, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Balcells, Marc [Isaac Newton Group of Telescopes, E-38700 Santa Cruz de La Palma, Canary Islands (Spain); Sánchez-Blázquez, Patricia, E-mail: trujillo@iac.es [Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049, Cantoblanco, Madrid (Spain)

2014-01-10

As early as 10 Gyr ago, galaxies with more than 10{sup 11} M {sub ☉} of stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (≲0.1%) may have survived untouched until today. Searches for such relic galaxies, useful windows to explore the early universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M {sub *} ≳ 10{sup 11} M {sub ☉}; R{sub e} ≲ 1.5 kpc) have been found in the local universe, but their stars are far too young for the galaxy to be a relic galaxy. This paper explores the first case of a nearby galaxy, NGC 1277 (at a distance of 73 Mpc in the Perseus galaxy cluster), which fulfills many criteria to be considered a relic galaxy. Using deep optical spectroscopy, we derive the star formation history along the structure of the galaxy: the stellar populations are uniformly old (>10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H] = 0.20 ± 0.04 with a smooth decline toward the outer regions) and α-enriched ([α/Fe] = 0.4 ± 0.1). This suggests a very short formation time scale for the bulk of the stars in this galaxy. This object also rotates very fast (V {sub rot} ∼ 300 km s{sup –1}) and has a large central velocity dispersion (σ > 300 km s{sup –1}). NGC 1277 allows the exploration in full detail of properties such as the structure, internal dynamics, metallicity, and initial mass function as they were at ∼10-12 Gyr ago when the first massive galaxies were built.

Could unstable relic particles distort the microwave background radiation?

International Nuclear Information System (INIS)

Dar, A.; Loeb, A.; Nussinov, S.

1989-01-01

Three general classes of possible scenarios for the recently reported distortion of the microwave background radiation (MBR) via decaying relic weakly interacting particles are analyzed. The analysis shows that such particles could not reheat the universe and cause the spectral distortion of the MBR. Gravitational processes such as the early formation of massive black holes may still be plausible energy sources for producing the reported spectral distortion of the MBR at an early cosmological epoch. 24 references

The 130 GeV gamma-ray line and Sommerfeld enhancements

International Nuclear Information System (INIS)

Chen, Jing; Zhou, Yu-Feng

2013-01-01

Recently, possible indications of line spectral features in the Fermi-LAT photon spectrum towards the galactic center have been reported. If the distinct line features arise from dark matter (DM) annihilation into γX(X = γ,Z 0 or h 0 ), the corresponding annihilation cross-section is unnaturally large for typical loop-induced radiative processes. On the other hand, it is still too small to be responsible for the observed DM relic density. We show that the mechanism of Sommerfeld enhancement with scalar force-carrier can provide a simple solution to these puzzles. The possibly large Sommerfeld enhancement of the cross-section for s-wave DM annihilation can significantly reduce the required effective couplings between DM and charged particles in typical loop diagrams. The DM particles necessarily annihilate into scalar force-carriers through tree-level p-wave process, which can dominate the total DM annihilation cross-section at freeze out, resulting in the correct thermal relic density, but has subdominant contributions to the DM annihilation today due to velocity suppression. We perform detailed analysis on the effects of p-wave Sommerfeld enhancement on freeze out. The results show that with the constraints from the thermal relic density, the required effective couplings can be reduced by an order of magnitude

Higgsino-like dark matter from sneutrino late decays

Directory of Open Access Journals (Sweden)

Anibal D. Medina

2017-07-01

Full Text Available We consider Higgsino-like dark matter (DM in the Minimal Supersymmetric Standard Model (MSSM with additional right-handed neutrino chiral superfields, and propose a new non-thermal way of generating the right amount of relic DM via sneutrino late decays. Due to the large DM annihilation cross-section, decays must occur at lower temperatures than the freeze-out temperature Td≪TF,χ˜10∼μ/25, implying a mostly right-handed lightest sneutrino with very small Yukawa interactions. In that context, the right amount of Higgsino-like DM relic density can be accounted for if sneutrinos are produced via thermal freeze-in in the early Universe.

Relics of short distance effects for the neutron electric dipole moment

International Nuclear Information System (INIS)

Eeg, J.O.

1982-12-01

The Feynman diagrams which dominate the estimates of the electric dipole moment of the neutron with Kobayashi-Maskawa CP violation are considered. The extracted long distance contributions and the relics of short distance contributions are shown to be complementary and of the same magnitude, resulting in mod(Dsub(n)/e) approximately = (10 - 31 - 10 - 30 ) cm. (Auth.)

Thermal Stress Effect on Density Changes of Hemp Hurds Composites

Science.gov (United States)

Schwarzova, Ivana; Cigasova, Julia; Stevulova, Nadezda

2016-12-01

The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

Thermal Stress Effect on Density Changes of Hemp Hurds Composites

Directory of Open Access Journals (Sweden)

Schwarzova Ivana

2016-12-01

Full Text Available The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution and physically (by ultrasonic procedure treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

THE SCALING RELATIONS AND THE FUNDAMENTAL PLANE FOR RADIO HALOS AND RELICS OF GALAXY CLUSTERS

International Nuclear Information System (INIS)

Yuan, Z. S.; Han, J. L.; Wen, Z. L.

2015-01-01

Diffuse radio emission in galaxy clusters is known to be related to cluster mass and cluster dynamical state. We collect the observed fluxes of radio halos, relics, and mini-halos for a sample of galaxy clusters from the literature, and calculate their radio powers. We then obtain the values of cluster mass or mass proxies from previous observations, and also obtain the various dynamical parameters of these galaxy clusters from optical and X-ray data. The radio powers of relics, halos, and mini-halos are correlated with the cluster masses or mass proxies, as found by previous authors, while the correlations concerning giant radio halos are in general the strongest. We found that the inclusion of dynamical parameters as the third dimension can significantly reduce the data scatter for the scaling relations, especially for radio halos. We therefore conclude that the substructures in X-ray images of galaxy clusters and the irregular distributions of optical brightness of member galaxies can be used to quantitatively characterize the shock waves and turbulence in the intracluster medium responsible for re-accelerating particles to generate the observed diffuse radio emission. The power of radio halos and relics is correlated with cluster mass proxies and dynamical parameters in the form of a fundamental plane

Investigation of laser cleaning on bronze cultural relics

International Nuclear Information System (INIS)

Ling, Xiulan; Wang, Gao; Zhang, Chen

2016-01-01

The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm −2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens. (paper)

Anharmonic thermal vibrations of be metal found in the MEM nuclear density map

International Nuclear Information System (INIS)

Takata, Masaki; Sakata, Makoto; Larsen, F.K.; Kumazawa, Shintaro; Iversen, B.B.

1993-01-01

A direct observation of the thermal vibrations of Be metal was performed by the Maximum Entropy Method (MEM) using neutron single crystal data. In the previous study, the existence of the small but significant cubic anharmonicity of Be has been found by the conventional least squares refinement of the observed structure factors [Larsen, Lehmann and Merisalo (1980) Acta Cryst. A36, 159-163]. In the present study, the same data were used for the MEM analysis which are comprised of 48 reflections up to sinθ/λ = 1.41A -1 in order to obtain the high resolution nuclear density of Be without using any thermal vibrational model. It was directly visible in the MEM map that not only the cubic terms but also quartic anharmonicities exist in the thermal vibrations of Be nuclei. In order to evaluate thermal parameters of Be including anharmonic terms quantitatively, the least squares refinement of the effective one-particle potential (OPP) parameters up to quartic term was carried out by using the MEM nuclear densities around atomic sites as the data set to be fitted. It was found that the present treatment has a great advantage to decide the most appropriate model of OPP by visually comparing the model with MEM density map. As a result of the least squares refinement, the anharmonic thermal parameters are obtained as α 33 = -0.340(5)[eV/A 3 ], α 40 = 0, β 20 = 9.89(1)[eV/A 4 ] and γ 00 = 0. No other anharmonic term was significant. (author)

[Research Progress of Raman Spectroscopy on Dyestuff Identification of Ancient Relics and Artifacts].

Science.gov (United States)

He, Qiu-ju; Wang, Li-qin

2016-02-01

As the birthplace of Silk Road, China has a long dyeing history. The valuable information about the production time, the source of dyeing material, dyeing process and preservation status were existed in organic dyestuff deriving from cultural relics and artifacts. However, because of the low contents, complex compositions and easily degraded of dyestuff, it is always a challenging task to identify the dyestuff in relics analyzing field. As a finger-print spectrum, Raman spectroscopy owns unique superiorities in dyestuff identification. Thus, the principle, characteristic, limitation, progress and development direction of micro-Raman spectroscopy (MRS/µ-Raman), near infrared reflection and Fourier transform Raman spectroscopy (NIR-FT-Raman), surface-enhanced Raman spectroscopy (SERS) and resonance raman spectroscopy (RRS) have been introduced in this paper. Furthermore, the features of Raman spectra of gardenia, curcumin and other natural dyestuffs were classified by MRS technology, and then the fluorescence phenomena of purpurin excitated with different wavelength laser was compared and analyzed. At last, gray green silver colloidal particles were made as the base, then the colorant of madder was identified combining with thin layer chromatography (TLC) separation technology and SERS, the result showed that the surface enhancement effect of silver colloidal particles could significantly reduce fluorescence background of the Raman spectra. It is pointed out that Raman spectroscopy is a rapid and convenient molecular structure qualitative methodology, which has broad application prospect in dyestuff analysis of cultural relics and artifacts. We propose that the combination of multi-Raman spectroscopy, separation technology and long distance transmission technology are the development trends of Raman spectroscopy.

Thermal expansion and density measurements of molten and solid materials at high temperatures by the gamma attenuation technique

International Nuclear Information System (INIS)

Drotning, W.D.

1979-05-01

An apparatus is described for the measurement of the density and thermal expansion of molten materials to 3200 0 K using the gamma attenuation technique. The precision of the experimental technique was analytically examined for both absolute and relative density determinations. Three analytical expressions used to reduce data for liquid density determinations were evaluated for their precision. Each allows use of a different set of input data parameters, which can be chosen based on experimental considerations. Using experimentally reasonable values for the precision of the parameters yields a similar resultant density precision from the three methods, on the order of 0.2%. The analytical method for measurements of the linear thermal expansion of solids by the gamma method is also described. To demonstrate the use of the technique on reasonably well-characterized systems, data are presented for (1) the density and thermal expansion of molten tin, lead, and aluminum to 1300 0 K, (2) the thermal expansion of solid aluminum to the melting point, and (3) the thermal expansion of a low melting point glass through the transition temperature and melting region. The data agree very well with published results using other methods where such published data exist

Direct detection of projectile relics from the end of the lunar basin-forming epoch.

Science.gov (United States)

Joy, Katherine H; Zolensky, Michael E; Nagashima, Kazuhide; Huss, Gary R; Ross, D Kent; McKay, David S; Kring, David A

2012-06-15

The lunar surface, a key proxy for the early Earth, contains relics of asteroids and comets that have pummeled terrestrial planetary surfaces. Surviving fragments of projectiles in the lunar regolith provide a direct measure of the types and thus the sources of exogenous material delivered to the Earth-Moon system. In ancient [>3.4 billion years ago (Ga)] regolith breccias from the Apollo 16 landing site, we located mineral and lithologic relics of magnesian chondrules from chondritic impactors. These ancient impactor fragments are not nearly as diverse as those found in younger (3.4 Ga to today) regolith breccias and soils from the Moon or that presently fall as meteorites to Earth. This suggests that primitive chondritic asteroids, originating from a similar source region, were common Earth-Moon-crossing impactors during the latter stages of the basin-forming epoch.

Detecting relic gravitational waves in the CMB: The contamination caused by the cosmological birefringence

Directory of Open Access Journals (Sweden)

Wen Zhao

2014-10-01

Full Text Available The B-mode polarization of the cosmic microwave background (CMB radiation is an excellent information channel for the detection of relic gravitational waves. However, the detection is contaminated by the B-mode polarization generated by some other effects. In this paper, we discuss the contaminations caused by the cosmological birefringence, which converts the CMB E-mode to the B-mode, and forms the effective noise for the detection of gravitational waves. We find that this contamination is significant, if the rotation angle is large. However, this kind of B-mode can be properly de-rotated, and the effective noises can be greatly reduced. We find that, comparing with the contaminations caused by cosmic weak lensing, the residual polarization generated by the cosmological birefringence is negligible for the detection of relic gravitational waves in the CMB.

Superheavy dark matter

CERN Document Server

Riotto, Antonio

2000-01-01

It is usually thought that the present mass density of the Universe is dominated by a weakly interacting massive particle (WIMP), a fossil relic of the early Universe. Theoretical ideas and experimental efforts have focused mostly on production and detection of thermal relics, with mass typically in the range a few GeV to a hundred GeV. Here, we will review scenarios for production of nonthermal dark matter whose mass may be in the range 10/sup 12/ to 10/sup 19/ GeV, much larger than the mass of thermal wimpy WIMPS. We will also review recent related results in understanding the production of very heavy fermions through preheating after inflation. (19 refs).

Non-thermal production of minimal dark matter via right-handed neutrino decay

Energy Technology Data Exchange (ETDEWEB)

Aoki, Mayumi [Institute for Theoretical Physics, Kanazawa University,Kanazawa 920-1192 (Japan); Toma, Takashi [Laboratoire de Physique Théorique, CNRS - UMR 8627, Université de Paris-Sud 11,F-91405 Orsay Cedex (France); Vicente, Avelino [IFPA, Dep. AGO, Université de Liège,Bat B5, Sart-Tilman B-4000 Liège 1 (Belgium); Instituto de Física Corpuscular, CSIC-Universitat de València,Apdo. 22085, E-46071 Valencia (Spain)

2015-09-29

Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above O(10) TeV in order to reproduce the observed dark matter relic density. Motivated by this little drawback, in this paper we consider an extension of the MDM scenario by three right-handed neutrinos. Two specific choices for the MDM multiplet are studied: a fermionic SU(2){sub L} quintuplet and a scalar SU(2){sub L} septuplet. The lightest right-handed neutrino, with tiny Yukawa couplings, never reaches thermal equilibrium in the early universe and is produced by freeze-in. This creates a link between dark matter and neutrino physics: dark matter can be non-thermally produced by the decay of the lightest right-handed neutrino after freeze-out, allowing to lower significantly the dark matter mass. We discuss the phenomenology of the non-thermally produced MDM and, taking into account significant Sommerfeld corrections, we find that the dark matter mass must have some specific values in order not to be in conflict with the current bounds from gamma-ray observations.

Non-thermal production of minimal dark matter via right-handed neutrino decay

Energy Technology Data Exchange (ETDEWEB)

Aoki, Mayumi [Institute for Theoretical Physics, Kanazawa University, Kanazawa 920-1192 (Japan); Toma, Takashi [Laboratoire de Physique Théorique, CNRS - UMR 8627, Université de Paris-Sud 11, F-91405 Orsay Cedex (France); Vicente, Avelino, E-mail: mayumi@hep.s.kanazawa-u.ac.jp, E-mail: takashi.toma@th.u-psud.fr, E-mail: Avelino.Vicente@ulg.ac.be [IFPA, Dep. AGO, Université de Liège, Bat B5, Sart-Tilman B-4000 Liège 1 (Belgium)

2015-09-01

Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above O(10) TeV in order to reproduce the observed dark matter relic density. Motivated by this little drawback, in this paper we consider an extension of the MDM scenario by three right-handed neutrinos. Two specific choices for the MDM multiplet are studied: a fermionic SU(2){sub L} quintuplet and a scalar SU(2){sub L} septuplet. The lightest right-handed neutrino, with tiny Yukawa couplings, never reaches thermal equilibrium in the early universe and is produced by freeze-in. This creates a link between dark matter and neutrino physics: dark matter can be non-thermally produced by the decay of the lightest right-handed neutrino after freeze-out, allowing to lower significantly the dark matter mass. We discuss the phenomenology of the non-thermally produced MDM and, taking into account significant Sommerfeld corrections, we find that the dark matter mass must have some specific values in order not to be in conflict with the current bounds from gamma-ray observations.

Calculation of thermal-diffusion coefficients from plane-wave fluctuations in the heat energy density

International Nuclear Information System (INIS)

Palmer, B.J.

1994-01-01

A method to calculate the thermal diffusivity D T from spontaneous fluctuations in the local heat energy density is presented. Calculations of the thermal diffusivity are performed for the Lennard-Jones fluid, carbon dioxide, and water. The results for the Lennard-Jones fluid are in agreement with calculations of the thermal conductivity using Green-Kubo relations and nonequilibrium molecular-dynamics techniques. The results for carbon dioxide and water give thermal diffusivities within a factor of 2 of the experimental values

New Target for Cosmic Axion Searches

NARCIS (Netherlands)

Baumann, D.; Green, D.; Wallisch, B.

2016-01-01

Future cosmic microwave background experiments have the potential to probe the density of relativistic species at the subpercent level. This sensitivity allows light thermal relics to be detected up to arbitrarily high decoupling temperatures. Conversely, the absence of a detection would require

Suppressing gravitino thermal production with a temperature-dependent messenger coupling

International Nuclear Information System (INIS)

Badziak, Marcin; Dalianis, Ioannis; Lalak, Zygmunt

2016-01-01

We show that the constraints on GMSB theories from the gravitino cosmology can be significantly relaxed if the messenger-spurion coupling is temperature dependent. We demonstrate this novel mechanism in a scenario in which this coupling depends on the VEV of an extra singlet field S that interacts with the thermalized plasma which can result in a significantly suppressed gravitino production rate. In such a scenario the relic gravitino abundance is determined by the thermal dynamics of the S field and it is easy to fit the observed dark matter abundance evading the stringent constraints on the reheating temperature, thus making gravitino dark matter consistent with thermal leptogenesis.

(N)LSP decays and gravitino dark matter relic abundance in big divisor (nearly) SLagy D3/D7μ-split SUSY

Science.gov (United States)

Dhuria, Mansi; Misra, Aalok

2013-02-01

Using the (nearly) Ricci-flat Swiss-Cheese metric of Misra (2012) [1], in the context of a mobile space-time filling D3-brane restricted to a nearly special Lagrangian sub-manifold (in the large volume limit, the pull-back of the Kähler form close to zero and the real part of the pull-back of e, θ=π/2 times the nowhere-vanishing holomorphic three-form providing the volume form on the three-cycle) of the "big" divisor with (fluxed stacks of) space-time filling D7-branes also wrapping the "big" divisor (corresponding to a local minimum), we provide an explicit identification of the electron and the u-quark, as well as their SU (2-singlet cousins, with fermionic superpartners of four Wilson line moduli; their superpartners turn out to be very heavy, the Higgsino-mass parameter turns out to be large, one obtains one light (with a mass of 125 GeV) and one heavy Higgs and the gluino is long lived (from a collider point of view) providing a possible realization of "μ-Split Supersymmetry". By explicitly calculating the lifetimes of decays of the co-NLSPs - the first generation squark/slepton and a neutralino - to the LSP - the gravitino - as well as gravitino decays, we verify that BBN constraints relevant to the former as well as the requirement of the latter to be (more than) the age of the universe, are satisfied. For the purpose of calculation of the gravitino relic density in terms of the neutralino/slepton relic density, we evaluate the latter by evaluating the neutralino/slepton (co-)annihilation cross sections and hence show that the former satisfies the requirement for a dark matter candidate.

(N)LSP decays and gravitino dark matter relic abundance in big divisor (nearly) SLagy D3/D7μ-split SUSY

International Nuclear Information System (INIS)

Dhuria, Mansi; Misra, Aalok

2013-01-01

Using the (nearly) Ricci-flat Swiss-Cheese metric of Misra (2012) [1], in the context of a mobile space–time filling D3-brane restricted to a nearly special Lagrangian sub-manifold (in the large volume limit, the pull-back of the Kähler form close to zero and the real part of the pull-back of e −iθ , θ=(π)/2 times the nowhere-vanishing holomorphic three-form providing the volume form on the three-cycle) of the “big” divisor with (fluxed stacks of) space–time filling D7-branes also wrapping the “big” divisor (corresponding to a local minimum), we provide an explicit identification of the electron and the u-quark, as well as their SU(2) L -singlet cousins, with fermionic superpartners of four Wilson line moduli; their superpartners turn out to be very heavy, the Higgsino-mass parameter turns out to be large, one obtains one light (with a mass of 125 GeV) and one heavy Higgs and the gluino is long lived (from a collider point of view) providing a possible realization of “μ-Split Supersymmetry”. By explicitly calculating the lifetimes of decays of the co-NLSPs – the first generation squark/slepton and a neutralino – to the LSP – the gravitino – as well as gravitino decays, we verify that BBN constraints relevant to the former as well as the requirement of the latter to be (more than) the age of the universe, are satisfied. For the purpose of calculation of the gravitino relic density in terms of the neutralino/slepton relic density, we evaluate the latter by evaluating the neutralino/slepton (co-)annihilation cross sections and hence show that the former satisfies the requirement for a dark matter candidate.

(N)LSP decays and gravitino dark matter relic abundance in big divisor (nearly) SLagy D3/D7{mu}-split SUSY

Energy Technology Data Exchange (ETDEWEB)

Dhuria, Mansi, E-mail: mansidph@iitr.ernet.in [Department of Physics, Indian Institute of Technology, Roorkee 247 667, Uttaranchal (India); Misra, Aalok, E-mail: aalokfph@iitr.ernet.in [Department of Physics, Indian Institute of Technology, Roorkee 247 667, Uttaranchal (India)

2013-02-21

Using the (nearly) Ricci-flat Swiss-Cheese metric of Misra (2012) [1], in the context of a mobile space-time filling D3-brane restricted to a nearly special Lagrangian sub-manifold (in the large volume limit, the pull-back of the Kaehler form close to zero and the real part of the pull-back of e{sup -i{theta}}, {theta}=({pi})/2 times the nowhere-vanishing holomorphic three-form providing the volume form on the three-cycle) of the 'big' divisor with (fluxed stacks of) space-time filling D7-branes also wrapping the 'big' divisor (corresponding to a local minimum), we provide an explicit identification of the electron and the u-quark, as well as their SU(2){sub L}-singlet cousins, with fermionic superpartners of four Wilson line moduli; their superpartners turn out to be very heavy, the Higgsino-mass parameter turns out to be large, one obtains one light (with a mass of 125 GeV) and one heavy Higgs and the gluino is long lived (from a collider point of view) providing a possible realization of '{mu}-Split Supersymmetry'. By explicitly calculating the lifetimes of decays of the co-NLSPs - the first generation squark/slepton and a neutralino - to the LSP - the gravitino - as well as gravitino decays, we verify that BBN constraints relevant to the former as well as the requirement of the latter to be (more than) the age of the universe, are satisfied. For the purpose of calculation of the gravitino relic density in terms of the neutralino/slepton relic density, we evaluate the latter by evaluating the neutralino/slepton (co-)annihilation cross sections and hence show that the former satisfies the requirement for a dark matter candidate.

The refractive index of relic gravitons

CERN Document Server

Giovannini, Massimo

2016-01-01

The dynamical evolution of the refractive index of the tensor modes of the geometry produces a specific class of power spectra characterized by a blue (i.e. slightly increasing) slope which is directly determined by the competition of the slow-roll parameter and of the rate of variation of the refractive index. Throughout the conventional stages of the inflationary and post-inflationary evolution, the microwave background anisotropies measurements, the pulsar timing limits and the big-bang nucleosythesis constraints set stringent bounds on the refractive index and on its rate of variation. Within the physically allowed region of the parameter space the cosmic background of relic gravitons leads to a potentially large signal for the ground based detectors (in their advanced version) and for the proposed space-borne interferometers. Conversely, the lack of direct detection of the signal will set a qualitatively new bound on the dynamical variation of the refractive index.

Effects of QCD bound states on dark matter relic abundance

Energy Technology Data Exchange (ETDEWEB)

Liew, Seng Pei [Department of Physics, The University of Tokyo,Bunkyo-ku, Tokyo 113-0033 (Japan); Luo, Feng [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan)

2017-02-17

We study scenarios where there exists an exotic massive particle charged under QCD in the early Universe. We calculate the formation and dissociation rates of bound states formed by pairs of these particles, and apply the results in dark matter (DM) coannihilation scenarios, including also the Sommerfeld effect. We find that on top of the Sommerfeld enhancement, bound-state effects can further significantly increase the largest possible DM masses which can give the observed DM relic abundance, by ∼30–100% with respect to values obtained by considering the Sommerfeld effect only, for the color triplet or octet exotic particles we consider. In particular, it indicates that the Bino DM mass in the right-handed stop-Bino coannihilation scenario in the Minimal Supersymmetric extension of the Standard Model (MSSM) can reach ∼2.5 TeV, even though the potential between the stop and antistop prior to forming a bound state is repulsive. We also apply the bound-state effects in the calculations of relic abundance of long-lived or metastable massive colored particles, and discuss the implications on the BBN constraints and the abundance of a super-weakly interacting DM. The corrections for the bound-state effect when the exotic massive colored particles also carry electric charges, and the collider bounds are also discussed.

D-brane disformal coupling and thermal dark matter

Science.gov (United States)

Dutta, Bhaskar; Jimenez, Esteban; Zavala, Ivonne

2017-11-01

Conformal and disformal couplings between a scalar field and matter occur naturally in general scalar-tensor theories. In D-brane models of cosmology and particle physics, these couplings originate from the D-brane action describing the dynamics of its transverse (the scalar) and longitudinal (matter) fluctuations, which are thus coupled. During the post-inflationary regime and before the onset of big bang nucleosynthesis (BBN), these couplings can modify the expansion rate felt by matter, changing the predictions for the thermal relic abundance of dark matter particles and thus the annihilation rate required to satisfy the dark matter content today. We study the D-brane-like conformal and disformal couplings effect on the expansion rate of the Universe prior to BBN and its impact on the dark matter relic abundance and annihilation rate. For a purely disformal coupling, the expansion rate is always enhanced with respect to the standard one. This gives rise to larger cross sections when compared to the standard thermal prediction for a range of dark matter masses, which will be probed by future experiments. In a D-brane-like scenario, the scale at which the expansion rate enhancement occurs depends on the string coupling and the string scale.

The Density of Mid-sized Kuiper Belt Objects from ALMA Thermal Observations

Energy Technology Data Exchange (ETDEWEB)

Brown, Michael E. [California Institute of Technology, 1200 E California Blvd., Pasadena CA 91125 (United States); Butler, Bryan J. [National Radio Astronomy Observatory, 1003 Lopezville Rd., Socorro NM 87801 (United States)

2017-07-01

The densities of mid-sized Kuiper Belt objects (KBOs) are a key constraint in understanding the assembly of objects in the outer solar system. These objects are critical for understanding the currently unexplained transition from the smallest KBOs with densities lower than that of water, to the largest objects with significant rock content. Mapping this transition is made difficult by the uncertainties in the diameters of these objects, which maps into an even larger uncertainty in volume and thus density. The substantial collecting area of the Atacama Large Millimeter Array allows significantly more precise measurements of thermal emission from outer solar system objects and could potentially greatly improve the density measurements. Here we use new thermal observations of four objects with satellites to explore the improvements possible with millimeter data. We find that effects due to effective emissivity at millimeter wavelengths make it difficult to use the millimeter data directly to find diameters and thus volumes for these bodies. In addition, we find that when including the effects of model uncertainty, the true uncertainties on the sizes of outer solar system objects measured with radiometry are likely larger than those previously published. Substantial improvement in object sizes will likely require precise occultation measurements.

Codecaying Dark Matter.

Science.gov (United States)

Dror, Jeff Asaf; Kuflik, Eric; Ng, Wee Hao

2016-11-18

We propose a new mechanism for thermal dark matter freeze-out, called codecaying dark matter. Multicomponent dark sectors with degenerate particles and out-of-equilibrium decays can codecay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes codecaying dark matter.

Scalar Dark Matter From Theory Space

Energy Technology Data Exchange (ETDEWEB)

Birkedal-Hansen, Andreas; Wacker, Jay G.

2003-12-26

The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass {Omicron}(100 GeV), the second region has a candidate with a mass greater than {Omicron}(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible WIMP (weakly interacting massive particle).

Scalar dark matter from theory space

International Nuclear Information System (INIS)

Birkedal-Hansen, Andreas; Wacker, Jay G.

2004-01-01

The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass O(100 GeV), the second region has a candidate with a mass greater than O(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible weakly interacting massive particle

Constructing Teaching Model for Training English Guides of Stone In-scription Relics

Institute of Scientific and Technical Information of China (English)

李慧

2016-01-01

A teaching model based on constructivism is proposed in this paper. The model contains five teaching steps, e.g. inter-pretation teaching, questioning-dialogue, knowledge and skills teaching, discussion-collaboration and field training. Practice proves that it can effectively improve the training efficiency of the training of English guides of stone inscription relics and en-hance their interpretation quality and English skills.

Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

Directory of Open Access Journals (Sweden)

S. Zare

2015-04-01

Full Text Available Propagation of a Gaussian x-ray laser beam has been analyzed in collisionless thermal quantum plasma with considering a ramped density profile. In this density profile due to the increase in the plasma density, an earlier and stronger self-focusing effect is noticed where the beam width oscillates with higher frequency and less amplitude. Moreover, the effect of the density profile slope and the initial plasma density on the laser propagation has been studied. It is found that, by increasing the initial density and the ramp slope, the laser beam focuses faster with less oscillation amplitude, smaller laser spot size and more oscillations. Furthermore, a comparison is made among the laser self-focusing in thermal quantum plasma, cold quantum plasma and classical plasma. It is realized that the laser self-focusing in the quantum plasma becomes stronger in comparison with the classical regime.

Development of the fabrication of ultra-low density ploy (4-methyl-1-pentene) (PMP) foams by thermal induced phase-inversion technique

International Nuclear Information System (INIS)

Zhang Lin; Wang Chaoyang; Luo Xuan; Du Kai; Tu Haiyan; Fan Hong; Luo Qing; Yuan Guanghui; Huang Lizhen

2003-01-01

By thermally induced phase-inversion technique, ploy (4-methyl-1-pentene) (PMP) foams are successfully prepared; the density and pore size are 3-80 mg/cm 3 and 1-20 μm respectively. Durene/naphthalene (60/40) is confirmed as the suitable solvent/nonsolvent binary system. The PMP's thermal properties are characterized by TG-DSC system. It is found that the foams thermal properties depend on the density. The thermal analysis method is utilized to measure the gelation of PMP in the binary solvent/nonsolvent system. The range of gelation temperature is preliminarily determined. The influence of mixture system composition and the cooling rate during the making of foams is discussed. TG-DSC is applied to determine the thermal properties of low-density PMP foams prepared in the laboratory. And the effect of density change on the thermal stability of foams are studied. The thermal analysis data play a great role in improving the foam quality. (authors)

Effects of nano-void density, size and spatial population on thermal conductivity: a case study of GaN crystal

International Nuclear Information System (INIS)

Zhou, X W; Jones, R E

2012-01-01

The thermal conductivity of a crystal is sensitive to the presence of surfaces and nanoscale defects. While this opens tremendous opportunities to tailor thermal conductivity, true ‘phonon engineering’ of nanocrystals for a specific electronic or thermoelectric application can only be achieved when the dependence of thermal conductivity on the defect density, size and spatial population is understood and quantified. Unfortunately, experimental studies of the effects of nanoscale defects are quite challenging. While molecular dynamics simulations are effective in calculating thermal conductivity, the defect density range that can be explored with feasible computing resources is unrealistically high. As a result, previous work has not generated a fully detailed understanding of the dependence of thermal conductivity on nanoscale defects. Using GaN as an example, we have combined a physically motivated analytical model and highly converged large-scale molecular dynamics simulations to study the effects of defects on thermal conductivity. An analytical expression for thermal conductivity as a function of void density, size, and population has been derived and corroborated with the model, simulations, and experiments. (paper)

The Variable and Changing Status of Performance Art Relics and Artifacts in Museum Collections

DEFF Research Database (Denmark)

Cone, Louise

2017-01-01

The status of an artwork in a museum collection is variable and contingent upon factors and parameters that are specific not only to the logic of the museum world but also to factors extrinsic to the museum. In particular older performance art 'relics' are subject to contextual interpretations...

WIMPless dark matter from non-Abelian hidden sectors with anomaly-mediated supersymmetry breaking

International Nuclear Information System (INIS)

Feng, Jonathan L.; Shadmi, Yael

2011-01-01

In anomaly-mediated supersymmetry breaking models, superpartner masses are proportional to couplings squared. Their hidden sectors therefore naturally contain WIMPless dark matter, particles whose thermal relic abundance is guaranteed to be of the correct size, even though they are not weakly interacting massive particles. We study viable dark matter candidates in WIMPless anomaly-mediated supersymmetry breaking models with non-Abelian hidden sectors and highlight unusual possibilities that emerge in even the simplest models. In one example with a pure SU(N) hidden sector, stable hidden gluinos freeze out with the correct relic density, but have an extremely low, but natural, confinement scale, providing a framework for self-interacting dark matter. In another simple scenario, hidden gluinos freeze out and decay to visible Winos with the correct relic density, and hidden glueballs may either be stable, providing a natural framework for mixed cold-hot dark matter, or may decay, yielding astrophysical signals. Last, we present a model with light hidden pions that may be tested with improved constraints on the number of nonrelativistic degrees of freedom. All of these scenarios are defined by a small number of parameters, are consistent with gauge coupling unification, preserve the beautiful connection between the weak scale and the observed dark matter relic density, and are natural, with relatively light visible superpartners. We conclude with comments on interesting future directions.

Influence of reagents mixture density on the radiation-thermal synthesis of lithium-zinc ferrites

Science.gov (United States)

Surzhikov, A. P.; Lysenko, E. N.; Vlasov, V. A.; Malyshev, A. V.; Korobeynikov, M. V.; Mikhailenko, M. A.

2017-01-01

Influence of Li2CO3-ZnO-Fe2O3 powder reagents mixture density on the synthesis efficiency of lithium-zinc ferrites in the conditions of thermal heating or pulsed electron beam heating was studied by X-Ray diffraction and magnetization analysis. The results showed that the including a compaction of powder reagents mixture in ferrite synthesis leads to an increase in concentration of the spinel phase and decrease in initial components content in lithium-substituted ferrites synthesized by thermal or radiation-thermal heating.

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

International Nuclear Information System (INIS)

Van Weeren, R. J.; Jones, C.; Forman, W. R.; Andrade-Santos, F.; Pearce, Connor J. J.; David, L.; Kraft, R. P.; Nulsen, P. E. J.; Ogrean, G. A.; Bonafede, A.; Brüggen, M.; Bulbul, E.; Clarke, T. E.; Churazov, E.; Dawson, W. A.; Donahue, M.; Goulding, A.; Mason, B.; Merten, J.; Mroczkowski, T.

2017-01-01

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeast of this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Energy Technology Data Exchange (ETDEWEB)

Van Weeren, R. J.; Jones, C.; Forman, W. R.; Andrade-Santos, F.; Pearce, Connor J. J.; David, L.; Kraft, R. P.; Nulsen, P. E. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ogrean, G. A. [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Bonafede, A.; Brüggen, M. [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Bulbul, E. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Clarke, T. E. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375 (United States); Churazov, E. [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany); Dawson, W. A. [Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94550 (United States); Donahue, M. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Goulding, A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Mason, B. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Merten, J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu [ESO—European Organization for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München (Germany); and others

2017-02-01

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeast of this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.

POWER SPECTRAL DENSITY OF FLUCTUATIONS OF BULK AND THERMAL SPEEDS IN THE SOLAR WIND

International Nuclear Information System (INIS)

Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L.; Chen, C. H. K.; Zastenker, G. N.

2016-01-01

This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s 1 bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are 1.43 and 1.38, respectively, whereas they are 3.08 and 2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

POWER SPECTRAL DENSITY OF FLUCTUATIONS OF BULK AND THERMAL SPEEDS IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L. [Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Chen, C. H. K. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Zastenker, G. N., E-mail: jana.safrankova@mff.cuni.cz [Space Research Institute of Russian Academy of Sciences, Moscow, Russia, Profsoyuznaya ul. 84/32, Moscow 117997 (Russian Federation)

2016-07-10

This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s{sup 1} bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are 1.43 and 1.38, respectively, whereas they are 3.08 and 2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

Cosmological implications of a dark matter self-interaction energy density

International Nuclear Information System (INIS)

Stiele, Rainer; Boeckel, Tillmann; Schaffner-Bielich, Juergen

2010-01-01

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle m SI and coupling constant α SI . Because of the expansion behavior in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behavior of dark matter self-interaction energy density (ρ SI ∝a -6 ) shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength m SI /√(α SI ), which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict superweak inelastic interactions between self-interacting dark matter and baryonic matter (σ A SIDM weak ) and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale (σ A CDM >σ weak ) and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination (δ∝a); however, only noncosmological scales are enhanced.

Review of thermal expansion and density of uranium and plutonium carbides

International Nuclear Information System (INIS)

Andrew, J.F.; Latimer, T.W.

1975-07-01

The published literature on linear thermal expansion and density of uranium and plutonium carbide nuclear fuels, including UC, PuC, (U,Pu)C, U 2 C 3 , Pu 2 C 3 , and (U,Pu) 2 C 3 , is critically reviewed. Recommended values are given in tabular form and additional experimental studies needed for completeness are outlined. 16 tables, 52 references

AMS radiocarbon dating of medieval textile relics: The frocks and the pillow of St. Francis of Assisi

Energy Technology Data Exchange (ETDEWEB)

Fedi, M.E. [Dipartimento di Fisica dell' Universita di Firenze and INFN Sezione di Firenze, via Sansone 1, 50019 Sesto Fiorentino (Italy)], E-mail: fedi@fi.infn.it; Cartocci, A.; Taccetti, F.; Mando, P.A. [Dipartimento di Fisica dell' Universita di Firenze and INFN Sezione di Firenze, via Sansone 1, 50019 Sesto Fiorentino (Italy)

2008-05-15

Since natural textiles usually originate from short-lived organisms, they can represent a useful material to date samples from historical periods with a good accuracy. In this work, we present a set of radiocarbon measurements on medieval textile relics: two woollen habits and a pillow traditionally associated with St. Francis of Assisi, the saint patron of Italy. The strategy in choosing samples for radiocarbon dating is first discussed and the procedures for measurements - performed at the 3 MV Tandetron accelerator of Laboratorio di Tecniche Nucleari per i Beni Culturali (LABEC), Florence - are described; AMS results for the two frocks showed that only one of them, presently kept in the church of St. Francis in Cortona, is compatible with the Saint's period of life, as is the pillow also kept in Cortona. Another frock attributed to St. Francis appears to date from at least 80 years after his death. However, the goal of these measurements was not a bare authentication/disconfirmation of the relics; they just represent an example of how scientific analysis can integrate with humanistic studies. Indeed, AMS results, combined with a thorough analysis of the textiles typologies, confirmed the historical hypotheses based on documentary studies and on tradition. The overall conclusions contributed to the decisions taken for conservation, and have as a whole enhanced the religious importance of the relics.

AMS radiocarbon dating of medieval textile relics: The frocks and the pillow of St. Francis of Assisi

International Nuclear Information System (INIS)

Fedi, M.E.; Cartocci, A.; Taccetti, F.; Mando, P.A.

2008-01-01

Since natural textiles usually originate from short-lived organisms, they can represent a useful material to date samples from historical periods with a good accuracy. In this work, we present a set of radiocarbon measurements on medieval textile relics: two woollen habits and a pillow traditionally associated with St. Francis of Assisi, the saint patron of Italy. The strategy in choosing samples for radiocarbon dating is first discussed and the procedures for measurements - performed at the 3 MV Tandetron accelerator of Laboratorio di Tecniche Nucleari per i Beni Culturali (LABEC), Florence - are described; AMS results for the two frocks showed that only one of them, presently kept in the church of St. Francis in Cortona, is compatible with the Saint's period of life, as is the pillow also kept in Cortona. Another frock attributed to St. Francis appears to date from at least 80 years after his death. However, the goal of these measurements was not a bare authentication/disconfirmation of the relics; they just represent an example of how scientific analysis can integrate with humanistic studies. Indeed, AMS results, combined with a thorough analysis of the textiles typologies, confirmed the historical hypotheses based on documentary studies and on tradition. The overall conclusions contributed to the decisions taken for conservation, and have as a whole enhanced the religious importance of the relics

AMS radiocarbon dating of medieval textile relics: The frocks and the pillow of St. Francis of Assisi

Science.gov (United States)

Fedi, M. E.; Cartocci, A.; Taccetti, F.; Mandò, P. A.

2008-05-01

Since natural textiles usually originate from short-lived organisms, they can represent a useful material to date samples from historical periods with a good accuracy. In this work, we present a set of radiocarbon measurements on medieval textile relics: two woollen habits and a pillow traditionally associated with St. Francis of Assisi, the saint patron of Italy. The strategy in choosing samples for radiocarbon dating is first discussed and the procedures for measurements - performed at the 3 MV Tandetron accelerator of Laboratorio di Tecniche Nucleari per i Beni Culturali (LABEC), Florence - are described; AMS results for the two frocks showed that only one of them, presently kept in the church of St. Francis in Cortona, is compatible with the Saint's period of life, as is the pillow also kept in Cortona. Another frock attributed to St. Francis appears to date from at least 80 years after his death. However, the goal of these measurements was not a bare authentication/disconfirmation of the relics; they just represent an example of how scientific analysis can integrate with humanistic studies. Indeed, AMS results, combined with a thorough analysis of the textiles typologies, confirmed the historical hypotheses based on documentary studies and on tradition. The overall conclusions contributed to the decisions taken for conservation, and have as a whole enhanced the religious importance of the relics.

Constraints on the cosmological relativistic energy density

International Nuclear Information System (INIS)

Zentner, Andrew R.; Walker, Terry P.

2002-01-01

We discuss bounds on the cosmological relativistic energy density as a function of redshift, reviewing the big bang nucleosynthesis and cosmic microwave background bounds, updating bounds from large scale structure, and introducing a new bound from the magnitude-redshift relation for type Ia supernovae. We conclude that the standard and well-motivated assumption that relativistic energy is negligible during recent epochs is not necessitated by extant data. We then demonstrate the utility of these bounds by constraining the mass and lifetime of a hypothetical massive big bang relic particle

Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

International Nuclear Information System (INIS)

Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

2015-01-01

Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established

Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2015-12-15

Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

Relic gravity waves from braneworld inflation

International Nuclear Information System (INIS)

Sahni, Varun; Sami, M.; Souradeep, Tarun

2002-01-01

We discuss a scenario in which extra dimensional effects allow a scalar field with a steep potential to play the dual role of the inflaton as well as dark energy (quintessence). The post-inflationary evolution of the universe in this scenario is generically characterized by a 'kinetic regime' during which the kinetic energy of the scalar field greatly exceeds its potential energy resulting in a 'stiff' equation of state for scalar field matter P φ ≅ρ φ . The kinetic regime precedes the radiation dominated epoch and introduces an important new feature into the spectrum of relic gravity waves created quantum mechanically during inflation. The amplitude of the gravity wave spectrum increases with the wave number for wavelengths shorter than the comoving horizon scale at the commencement of the radiative regime. This 'blue tilt' is a generic feature of models with steep potentials and imposes strong constraints on a class of inflationary braneworld models. Prospects for detection of the gravity wave background by terrestrial and space-borne gravity wave observatories such as LIGO II and LISA are discussed

Unitarity limits on the mass and radius of dark matter particles

Science.gov (United States)

Griest, Kim; Kamionkowski, Marc

1989-01-01

Using partial wave unitarity and the observed density of the Universe, it is show that a stable elementary particle which was once in thermal equilibrium cannot have a mass greater than 340 TeV. An extended object which was once in thermal equilibrium cannot have a radius less than 7.5 x 10(exp -7) fm. A lower limit to the relic abundance of such particles is also found.

Detection of a Double Relic in the Torpedo Cluster: SPT-CL J0245-5302

Science.gov (United States)

Zheng, Q.; Johnston-Hollitt, M.; Duchesne, S. W.; Li, W. T.

2018-06-01

The Torpedo cluster, SPT-CL J0245-5302 (S0295) is a massive, merging cluster at a redshift of z = 0.300, which exhibits a strikingly similar morphology to the Bullet cluster 1E 0657-55.8 (z = 0.296), including a classic bow shock in the cluster's intra-cluster medium revealed by Chandra X-ray observations. We present Australia Telescope Compact Array data centred at 2.1 GHz and Murchison Widefield Array data at frequencies between 72 MHz and 231 MHz which we use to study the properties of the cluster. We characterise a number of discrete and diffuse radio sources in the cluster, including the detection of two previously unknown radio relics on the cluster periphery. The average spectral index of the diffuse emission between 70 MHz and 3.1 GHz is α =-1.63_{-0.10}^{+0.10} and a radio-derived Mach number for the shock in the west of the cluster is calculated as M = 2.04. The Torpedo cluster is thus a double relic system at moderate redshift.

Relic gravitons from the pre-big bang: what we know and what we do not know

OpenAIRE

Gasperini, M.

1996-01-01

I discuss the status of present knowledge about a possible background of relic gravitons left by an early, pre-big bang cosmological epoch, whose existence in the past of our Universe is suggested by the duality symmetries of string theory.

Thermal properties of silica-filled high density polyethylene composites compatibilized with glut palmitate

Science.gov (United States)

Samsudin, Dalina; Ismail, Hanafi; Othman, Nadras; Hamid, Zuratul Ain Abdul

2017-07-01

A study of thermal properties resulting from the utilization of Glut Palmitate (GP) on the silica filled high density polyethylene (HDPE) composites was carried out. The composites with the incorporation of GP at 0.5, 1.0, 2.0 and 3.0 phr were prepared by using an internal mixer at the temperature 180 °C and the rotor speed of 50 rpm. The thermal behaviours of the composites were then investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the crystallinity and the thermal stability of the composites increased with the incorporation of GP. The highest crystallinity contents and decomposition temperatures were observed at the 1 phr GP loading.

Effect of Interface Structure on Thermal Boundary Conductance by using First-principles Density Functional Perturbation Theory

Institute of Scientific and Technical Information of China (English)

GAO Xue; ZHANG Yue; SHANG Jia-Xiang

2011-01-01

We choose a Si/Ge interface as a research object to investigate the infiuence of interface disorder on thermal boundary conductance. In the calculations, the diffuse mismatch model is used to study thermal boundary conductance between two non-metallic materials, while the phonon dispersion relationship is calculated by the first-principles density functional perturbation theory. The results show that interface disorder limits thermal transport. The increase of atomic spacing at the interface results in weakly coupled interfaces and a decrease in the thermal boundary conductance. This approach shows a simplistic method to investigate the relationship between microstructure and thermal conductivity.%We choose a Si/Ge interface as a research object to investigate the influence of interface disorder on thermal boundary conductance.In the calculations,the diffuse mismatch model is used to study thermal boundary conductance between two non-metallic materials,while the phonon dispersion relationship is calculated by the first-principles density functional perturbation theory.The results show that interface disorder limits thermal transport.The increase of atomic spacing at the interface results in weakly coupled interfaces and a decrease in the thermal boundary conductance.This approach shows a simplistic method to investigate the relationship between microstructure and thermal conductivity.It is well known that interfaces can play a dominant role in the overall thermal transport characteristics of structures whose length scale is less than the phonon mean free path.When heat flows across an interface between two different materials,there exists a temperature jump at the interface.Thermal boundary conductance (TBC),which describes the efficiency of heat flow at material interfaces,plays an importance role in the transport of thermal energy in nanometerscale devices,semiconductor superlattices,thin film multilayers and nanocrystalline materials.[1

Relocation of Intermediate-depth Seismicity in the Relic Alboran Slab: Clustering and Relationship to Tearing and Dehydration Embrittlement.

Science.gov (United States)

Sun, M.; Bezada, M.

2017-12-01

Intermediate-depth seismicity outside active subduction zones is rare. However, there is a well-known occurrence of such events in a N-S elongated volume between Spain and Morocco, within what most researchers consider to be the relic Alboran slab. Partial subduction of, and tearing from the adjoining continental lithosphere have been suggested in this area. We investigate whether dehydration embrittlement or shear instability is more consistent with the Alboran intermediate depth seismicity by considering their location relative to the expected thermal structure and expected areas of high strain rate associated with thinning or tearing of the slab. We use a dense temporary seismograph deployment in Spain and Morocco to relocate 65 intermediate-depth events occurring between 2010 and 2013 in this region. The relocation procedure is realized by a grid-search approach that minimizes the normalized misfit between the picked times and travel times calculated using a regional 3D velocity model. Results indicate that, compared with catalog results, hypocenters after relocation are more concentrated in space; they tend to shift southward and eastward while no systematic shift in depth is observed. Relocated hypocenters concentrate at a depth range between 50-100 km and along a narrow longitude range around 4.5W. Investigation of the earthquake density distribution indicates these earthquakes concentrate into several clusters. One such cluster sits above the spain-arm of the Alboran slab and beneath the Spain continental lithosphere, indicating that it is likely associated to the thinning process of the Alboran slab. The other four clusters all lie within the interior of the slab. Interestingly, two of them are near the middle of the subducted lithosphere and the other two lie near its base. This observation seems at odds with expectations based on the two leading hypotheses for enabling brittle failure at intermediate depths.

Ionization of liquid argon by x-rays: effect of density on electron thermalization and free ion yields

International Nuclear Information System (INIS)

Huang, S.S.-S.; Gee, N.; Freeman, G.R.

1991-01-01

Free ion yields were measured in liquid argon as a function of electric field strength at densities 736-1343 kg/m 3 (temperatures 149-95 K). The field dependence of the yields was parametrized using the extended Onsager and box models. Over the present density range the total ion yield was constant within 1% and was taken as 4.4, the average of earlier values at 87-91 K. The absence of internal vibrational modes in argon makes its electron thermalizing ability smaller than that of methane. The electron thermalization distance b GP in liquid argon is 3-5 times longer than that in liquid methane at a given d/d c (d c = critical fluid density). (author)

Parametric dependence of density limits in the Tokamak Experiment for Technology Oriented Research (TEXTOR): Comparison of thermal instability theory with experiment

International Nuclear Information System (INIS)

Kelly, F.A.; Stacey, W.M.; Rapp, J.

2001-01-01

The observed dependence of the TEXTOR [Tokamak Experiment for Technology Oriented Research: E. Hintz, P. Bogen, H. A. Claassen et al., Contributions to High Temperature Plasma Physics, edited by K. H. Spatschek and J. Uhlenbusch (Akademie Verlag, Berlin, 1994), p. 373] density limit on global parameters (I, B, P, etc.) and wall conditioning is compared with the predicted density limit parametric scaling of thermal instability theory. It is necessary first to relate the edge parameters of the thermal instability theory to n(bar sign) and the other global parameters. The observed parametric dependence of the density limit in TEXTOR is generally consistent with the predicted density limit scaling of thermal instability theory. The observed wall conditioning dependence of the density limit can be reconciled with the theory in terms of the radiative emissivity temperature dependence of different impurities in the plasma edge. The thermal instability theory also provides an explanation of why symmetric detachment precedes radiative collapse for most low power shots, while a multifaceted asymmetric radiation from the edge MARFE precedes detachment for most high power shots

Effects of ultrasound energy density on the non-thermal pasteurization of chocolate milk beverage.

Science.gov (United States)

Monteiro, Sara H M C; Silva, Eric Keven; Alvarenga, Verônica O; Moraes, Jeremias; Freitas, Mônica Q; Silva, Márcia C; Raices, Renata S L; Sant'Ana, Anderson S; Meireles, M Angela A; Cruz, Adriano G

2018-04-01

This study presents the emerging high-intensity ultrasound (HIUS) processing as a non-thermal alternative to high-temperature short-time pasteurization (HTST). Chocolate milk beverage (CMB) was subjected to different ultrasound energy densities (0.3-3.0 kJ/cm 3 ), as compared to HTST pasteurization (72 °C/15 s) aimed to verify the effect of the HIUS processing on the microbiological and physicochemical characteristics of the beverage. The application of HIUS at an energy density of 3.0 kJ/cm 3 was able to reduce 3.56 ± 0.02 logarithmic cycles in the total aerobic counts. In addition, the ultrasound energy density affected the physical properties of the beverage as the size distribution of fat globule and rheological behavior, as well as the chemical properties such as antioxidant activity, ACE inhibitory activity, fatty acid profile, and volatile profile. In general, the different energetic densities used as a non-thermal method of pasteurization of CMB were more effective when compared to the conventional pasteurization by HTST, since they improved the microbiological and physicochemical quality, besides preserving the bioactive compounds and the nutritional quality of the product. Copyright © 2017 Elsevier B.V. All rights reserved.

Late Quaternary sea level and environmental changes from relic carbonate deposits of the western margin of India

Digital Repository Service at National Institute of Oceanography (India)

Rao, V.P.; Rajagopalan, G.; Vora, K.H.; Almeida, F.

. The petrology and mineralogy of the deposits indicate that except for aragonite sands and foraminiferal nodules, the others were formed in shallow marine conditions and serve as sea level indicators. Radiocarbon dates were measured for 62 relic deposits covering...

Stable indications of relic gravitational waves in Wilkinson Microwave Anisotropy Probe data and forecasts for the Planck mission

International Nuclear Information System (INIS)

Zhao, W.; Baskaran, D.; Grishchuk, L. P.

2009-01-01

The relic gravitational waves are the cleanest probe of the violent times in the very early history of the Universe. They are expected to leave signatures in the observed cosmic microwave background anisotropies. We significantly improved our previous analysis [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. D 79, 023002 (2009)] of the 5-year WMAP TT and TE data at lower multipoles l. This more general analysis returned essentially the same maximum likelihood result (unfortunately, surrounded by large remaining uncertainties): The relic gravitational waves are present and they are responsible for approximately 20% of the temperature quadrupole. We identify and discuss the reasons by which the contribution of gravitational waves can be overlooked in a data analysis. One of the reasons is a misleading reliance on data from very high multipoles l and another a too narrow understanding of the problem as the search for B modes of polarization, rather than the detection of relic gravitational waves with the help of all correlation functions. Our analysis of WMAP5 data has led to the identification of a whole family of models characterized by relatively high values of the likelihood function. Using the Fisher matrix formalism we formulated forecasts for Planck mission in the context of this family of models. We explore in detail various 'optimistic', 'pessimistic', and 'dream case' scenarios. We show that in some circumstances the B-mode detection may be very inconclusive, at the level of signal-to-noise ratio S/N=1.75, whereas a smarter data analysis can reveal the same gravitational wave signal at S/N=6.48. The final result is encouraging. Even under unfavorable conditions in terms of instrumental noises and foregrounds, the relic gravitational waves, if they are characterized by the maximum likelihood parameters that we found from WMAP5 data, will be detected by Planck at the level S/N=3.65.

A Noncontact Measurement Technique for the Density and Thermal Expansion Coefficient of Solid and Liquid Materials

Science.gov (United States)

Chung, Sang K.; Thiessen, David B.; Rhim, Won-Kyu

1996-01-01

A noncontact measurement technique for the density and the thermal expansion refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diameter samples can be levitated, melted, and radiatively cooled in a vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 C. The result for the liquid phase density can be expressed by p = 8.848 + (6.730 x 10(exp -4)) x T (degC) g/cu cm within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by Beta=(9.419 x 10(exp -5)) - (7.165 x 10(exp -9) x T (degC)/K within 0.2% accuracy.

RNA Relics and Origin of Life

Directory of Open Access Journals (Sweden)

Laurent Vial

2009-07-01

Full Text Available A number of small RNA sequences, located in different non-coding sequences and highly preserved across the tree of life, have been suggested to be molecular fossils, of ancient (and possibly primordial origin. On the other hand, recent years have revealed the existence of ubiquitous roles for small RNA sequences in modern organisms, in functions ranging from cell regulation to antiviral activity. We propose that a single thread can be followed from the beginning of life in RNA structures selected only for stability reasons through the RNA relics and up to the current coevolution of RNA sequences; such an understanding would shed light both on the history and on the present development of the RNA machinery and interactions. After presenting the evidence (by comparing their sequences that points toward a common thread, we discuss a scenario of genome coevolution (with emphasis on viral infectious processes and finally propose a plan for the reevaluation of the stereochemical theory of the genetic code; we claim that it may still be relevant, and not only for understanding the origin of life, but also for a comprehensive picture of regulation in present-day cells.

RNA Relics and Origin of Life

Science.gov (United States)

Demongeot, Jacques; Glade, Nicolas; Moreira, Andrés; Vial, Laurent

2009-01-01

A number of small RNA sequences, located in different non-coding sequences and highly preserved across the tree of life, have been suggested to be molecular fossils, of ancient (and possibly primordial) origin. On the other hand, recent years have revealed the existence of ubiquitous roles for small RNA sequences in modern organisms, in functions ranging from cell regulation to antiviral activity. We propose that a single thread can be followed from the beginning of life in RNA structures selected only for stability reasons through the RNA relics and up to the current coevolution of RNA sequences; such an understanding would shed light both on the history and on the present development of the RNA machinery and interactions. After presenting the evidence (by comparing their sequences) that points toward a common thread, we discuss a scenario of genome coevolution (with emphasis on viral infectious processes) and finally propose a plan for the reevaluation of the stereochemical theory of the genetic code; we claim that it may still be relevant, and not only for understanding the origin of life, but also for a comprehensive picture of regulation in present-day cells. PMID:20111682

VizieR Online Data Catalog: Galaxy clusters: radio halos, relics and parameters (Yuan+, 2015)

Science.gov (United States)

Yuan, Z. S.; Han, J. L.; Wen, Z. L.

2017-10-01

A large number of radio halos, relics, and mini-halos have been discovered and measured in recent decades through observations with VLA (e.g., Giovannini & Feretti 2000NewA....5..335G; van Weeren et al. 2011A&A...533A..35V), GMRT (e.g., Venturi et al. 2007A&A...463..937V; Kale et al. 2015A&A...579A..92K), WSRT (e.g., van Weeren et al. 2010Sci...330..347V; Trasatti et al. 2015A&A...575A..45T), and also ATCA (e.g., Shimwell et al. 2014MNRAS.440.2901S, 2015MNRAS.449.1486S). We have checked the radio images of radio halos, relics, and mini-halos in the literature and collected in Table 1 the radio flux Sν at frequencies within a few per cent around 1.4 GHz, 610 MHz, and 325 MHz; we have interpolated the flux at an intermediate frequency if measurements are available at higher and lower frequencies. To establish reliable scaling relations, we include only the very firm detection of diffuse radio emission in galaxy clusters, and omit questionable detections or flux estimates due to problematic point-source subtraction. (3 data files).

Densities, isobaric thermal expansion coefficients and isothermal compressibilities of linear alkylbenzene

International Nuclear Information System (INIS)

Zhou, X; Zhang, Z Y; Zhang, Q M; Liu, Q; Ding, Y Y; Zhou, L; Cao, J

2015-01-01

We report the measurements of the densities of linear alkylbenzene at three temperatures over 4 to 23 °C with pressures up to 10 MPa. The measurements have been analysed to yield the isobaric thermal expansion coefficients and, so far for the first time, isothermal compressibilities of linear alkylbenzene. Relevance of results for current generation (i.e., Daya Bay) and next generation (i.e. JUNO) large liquid scintillator neutrino detectors are discussed. (paper)

Evaluation of thermal conductivity for liquid lead lithium alloys at various Li concentrations based on measurement and evaluation of density, thermal diffusivity and specific heat of alloys

Energy Technology Data Exchange (ETDEWEB)

Kondo, Masatoshi, E-mail: kondo.masatoshi@nr.titech.ac.jp [Tokyo Institute of Technology, 2-12-1, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan); Nakajima, Yuu; Tsuji, Mitsuyo [Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Nozawa, Takashi [Japan Atomic Energy Agency, Rokkasyo-mura, Kamikita-gun, Aomori 039-3212 (Japan)

2016-11-01

Graphical abstract: Thermal diffusivities and thermal conductivities of liquid Pb–Li alloys (Pb–5Li, Pb–11Li and Pb–17Li). - Highlights: • The densities and specific heats of liquid Pb–Li alloys are evaluated based on the previous studies, and mathematically expressed in the equations with the functions of temperature and Li concentration. • The thermal diffusivities of liquid Pb–Li alloys (i.e., Pb–5Li, Pb–11Li and Pb–17Li) are obtained by laser flash method, and mathematically expressed in the equations with the functions of temperature and Li concentration. • The thermal conductivities of liquid Pb–Li alloys were evaluated and mathematically expressed in the equations with the functions of temperature and Li concentration. - Abstract: The thermophysical properties of lead lithium alloy (Pb–Li) are essential for the design of liquid Pb–Li blanket system. The purpose of the present study is to make clear the density, the thermal diffusivity and the heat conductivity of the alloys as functions of temperature and Li concentration. The densities of the solid alloys were measured by means of the Archimedean method. The densities of the alloys at 300 K as a function of Li concentration (0 at% < χ{sub Li} < 28 at%) were obtained in the equation as ρ{sub (300} {sub K)} [g/cm{sup 3}] = −6.02 × 10{sup −2} × χ{sub Li} + 11.3. The density of the liquid alloys was formulated as functions of temperature and Li concentration (0 at% < χ{sub Li} < 30 at%), and expressed in the equation as ρ [g/cm{sup 3}] = (9.00 × 10{sup −6} × T − 7.01 × 10{sup −2}) × χ{sub Li} + 11.4 − 1.19 × 10{sup −3}T. The thermal diffusivity of Pb, Pb–5Li, Pb–11Li and Pb–17Li were measured by means of laser flash method. The thermal diffusivity of Pb–17Li was obtained in the equation as α{sub Pb–17Li} [cm{sup 2}/s] = 3.46 × 10{sup −4}T + 1.05 × 10{sup −1} for the temperature range between 573 K and 773 K. The thermal conductivity of

Quantum entanglement and thermal reduced density matrices in fermion and spin systems on ladders

International Nuclear Information System (INIS)

Chen, Xiao; Fradkin, Eduardo

2013-01-01

Numerical studies of the reduced density matrix of a gapped spin-1/2 Heisenberg antiferromagnet on a two-leg ladder find that it has the same form as the Gibbs density matrix of a gapless spin-1/2 Heisenberg antiferromagnetic chain at a finite temperature determined by the spin gap of the ladder. We investigate this interesting result by considering a model of free fermions on a two-leg ladder (gapped by the inter-chain tunneling operator) and in spin systems on a ladder with a gapped ground state using exact solutions and several controlled approximations. We calculate the reduced density matrix and the entanglement entropy for a leg of the ladder (i.e. a cut made between the chains). In the fermionic system we find the exact form of the reduced density matrix for one of the chains and determine the entanglement spectrum explicitly. Here we find that in the weak tunneling limit of the ladder the entanglement entropy of one chain of the gapped ladder has a simple and universal form dictated by conformal invariance. In the case of the spin system, we consider the strong coupling limit by using perturbation theory and get the reduced density matrix by the Schmidt decomposition. The entanglement entropies of a general gapped system of two coupled conformal field theories (in 1 + 1 dimensions) are discussed using the replica trick and scaling arguments. We show that (1) for a system with a bulk gap the reduced density matrix has the form of a thermal density matrix, (2) the long-wavelength modes of one subsystem (a chain) of a gapped coupled system are always thermal, (3) the von Neumann entropy equals the thermodynamic entropy of one chain, and (4) the bulk gap plays the role of effective temperature. (paper)

Thermal Experimental Analysis for Dielectric Characterization of High Density Polyethylene Nanocomposites

Directory of Open Access Journals (Sweden)

Ahmed Thabet Mohamed

2016-01-01

Full Text Available The importance of nanoparticles in controlling physical properties of polymeric nanocomposite materials leads us to study effects of these nanoparticles on electric and dielectric properties of polymers in industry In this research, the dielectric behaviour of High-Density Polyethylene (HDPE nanocomposites materials that filled with nanoparticles of clay or fumed silica has been investigated at various frequencies (10 Hz-1 kHz and temperatures (20-60°C. Dielectric spectroscopy has been used to characterize ionic conduction, then, the effects of nanoparticles concentration on the dielectric losses and capacitive charge of the new nanocomposites can be stated. Capacitive charge and loss tangent in high density polyethylene nanocomposites are measured by dielectric spectroscopy. Different dielectric behaviour has been observed depending on type and concentration of nanoparticles under variant thermal conditions.

DC Thermal Plasma Design and Utilization for the Low Density Polyethylene to Diesel Oil Pyrolysis Reaction

Directory of Open Access Journals (Sweden)

Hossam A. Gabbar

2017-06-01

Full Text Available The exponential increase of plastic production produces 100 million tonnes of waste plastics annually which could be converted into hydrocarbon fuels in a thermal cracking process called pyrolysis. In this research work, a direct current (DC thermal plasma circuit is designed and used for conversion of low density polyethylene (LDPE into diesel oil in a laboratory scale pyrolysis reactor. The experimental setup uses a 270 W DC thermal plasma at operating temperatures in the range of 625 °C to 860 °C for a low density polyethylene (LDPE pyrolysis reaction at pressure = −0.95, temperature = 550 °C with τ = 30 min at a constant heating rate of 7.8 °C/min. The experimental setup consists of a vacuum pump, closed system vessel, direct current (DC plasma circuit, and a k-type thermocouple placed a few millimeters from the reactant sample. The hydrocarbon products are condensed to diesel oil and analyzed using flame ionization detector (FID gas chromatography. The analysis shows 87.5% diesel oil, 1,4-dichlorobenzene (Surr, benzene, ethylbenzene and traces of toluene and xylene. The direct current (DC thermal plasma achieves 56.9 wt. % of diesel range oil (DRO, 37.8 wt. % gaseous products and minimal tar production. The direct current (DC thermal plasma shows reliability, better temperature control, and high thermal performance as well as the ability to work for long operation periods.

The thermal and mechanical properties of a low-density glass-fiber-reinforced elastomeric ablation material

Science.gov (United States)

Engelke, W. T.; Robertson, R. W.; Bush, A. L.; Pears, C. D.

1974-01-01

An evaluation of the thermal and mechanical properties was performed on a molded low-density elastomeric ablation material designated as Material B. Both the virgin and charred states were examined to provide meaningful inputs to the design of a thermal protection system. Chars representative of the flight chars formed during ablation were prepared in a laboratory furnace from 600 K to 1700 K and properties of effective thermal conductivity, heat capacity, porosity and permeability were determined on the furnace chars formed at various temperature levels within the range. This provided a boxing of the data which will enable the prediction of the transient response of the material during flight ablation.

Thermal Expansion and Density Data of UO2 and Simulated Fuel for Standard Reference

International Nuclear Information System (INIS)

Yang, Jae Hwan; Na, S. H.; Lee, J. W.; Kang, K. H.

2010-01-01

Standard Reference Data (SRD) is the scientific, technical data whose reliability and accuracy are evaluated by scientist group. Since SRD has a great impact on the improvement of national competitiveness by stirring up technological innovation in every sector of industries, many countries are making great efforts on establishing SRD in various areas. Data center for nuclear fuel material in Korea Atomic Energy Research Institute plays a role to providing property data of nuclear fuel material at high temperature, pressure, and radiation which are essential for the safety evaluation of nuclear power. In this study, standardization of data on thermal expansion and density of UO 2 were carried out in the temperature range from 300 K to 3100 K via uncertainty evaluation of indirectly produced data. Besides, standardization of data on thermal expansion and density of simulated fuel were also done in the temperature range from 350 K to 1750 K via uncertainty evaluation of directly produced data

Dissepiments, density bands and signatures of thermal stress in Porites skeletons

Science.gov (United States)

DeCarlo, Thomas M.; Cohen, Anne L.

2017-09-01

The skeletons of many reef-building corals are accreted with rhythmic structural patterns that serve as valuable sclerochronometers. Annual high- and low-density band couplets, visible in X-radiographs or computed tomography scans, are used to construct age models for paleoclimate reconstructions and to track variability in coral growth over time. In some corals, discrete, anomalously high-density bands, called "stress bands," preserve information about coral bleaching. However, the mechanisms underlying the formation of coral skeletal density banding remain unclear. Dissepiments—thin, horizontal sheets of calcium carbonate accreted by the coral to support the living polyp—play a key role in the upward growth of the colony. Here, we first conducted a vital staining experiment to test whether dissepiments were accreted with lunar periodicity in Porites coral skeleton, as previously hypothesized. Over 6, 15, and 21 months, dissepiments consistently formed in a 1:1 ratio to the number of full moons elapsed over each study period. We measured dissepiment spacing to reconstruct multiple years of monthly skeletal extension rates in two Porites colonies from Palmyra Atoll and in another from Palau that bleached in 1998 under anomalously high sea temperatures. Spacing between successive dissepiments exhibited strong seasonality in corals containing annual density bands, with narrow (wide) spacing associated with high (low) density, respectively. A high-density "stress band" accreted during the 1998 bleaching event was associated with anomalously low dissepiment spacing and missed dissepiments, implying that thermal stress disrupts skeletal extension. Further, uranium/calcium ratios increased within stress bands, indicating a reduction in the carbonate ion concentration of the coral's calcifying fluid under stress. Our study verifies the lunar periodicity of dissepiments, provides a mechanistic basis for the formation of annual density bands in Porites, and reveals the

Flower symbolism and the cult of relics in medieval Serbia

Directory of Open Access Journals (Sweden)

Popović Danica

2008-01-01

Full Text Available The Life of archbishop Eustathios I [Jevstatije] (1279-1286, deserving head of the medieval Serbian Church and a saint, is a very interesting source for studying the cult of relics with the Serbs. This is not surprising considering that the Life was penned by one of the most illustrious of Eustathios' successors on the church throne, Daniel II [Danilo], a learned Athonite and unquestionable master of the hagiographie literary genre. In his account of the life of his distinguished predecessor, Daniel describes extensively the events constituting the key stage in the glorification of a saint, namely Eustathios' death and posthumous occurrences at his grave. As most holy men, Eustathios foresaw his own death, and he departed from this world serenely. He was buried, with due honours, in the 'marble grave' he had prepared for himself in the cathedral church of Holy Saviour at Žiča. In keeping with the well-established saint-making process, a few years after the funeral 'extraordinary signs' began to occur at the archbishop's grave, in this particular case, candlelight and a multitude of murmuring voices followed by the miraculous cure of an incurably ill person. These occurrences preceded the great miracle which, to the best of my knowledge, is unparalleled in the medieval Serbian practice of relic veneration. Namely, 'one day they found growing from his marble grave three flowers endowed with wondrous beauty and impossible to liken to anything else. For, indeed, they were not of earthly humidity or of union with flowers that grow from earth; but, o wonder, how a dry stone standing for so long in the church could send forth fragrant flowers, to the renewal of the sanctified one's body'. Flower metaphors occur in the Service to the holy archbishop Eustathios, yet another piece penned by Daniel II, notably in his paraphrases of Psalm 92, 12-14 ('The righteous shall flourish like the palm tree: he shall grow like a cedar in Lebanon. These that be

Extremely high-power-density atmospheric-pressure thermal plasma jet generated by the nitrogen-boosted effect

Science.gov (United States)

Hanafusa, Hiroaki; Nakashima, Ryosuke; Nakano, Wataru; Higashi, Seiichiro

2018-06-01

In this study, the effect of N2 addition to an atmospheric-pressure Ar thermal plasma jet (TPJ) on ultrarapid heating was investigated. With increasing N2 flow rate, a boost of arc voltage to ∼36 V was observed, which significantly improved heating characteristics. As a result, a drastic power density increase from 10 to 125 kW/cm2 was achieved with the addition of 2.0 L/min N2 to 3.0 L/min Ar. The results of optical emission analysis and heating characteristics evaluation implied that dissociation and recombination of N2 molecules and the high thermal transport property of nitrogen gas play important roles in the increase in TPJ power density. Furthermore, we obtained TPJ extension with N2 addition that reached 300 mm, and it showed spatial enhancement of heat transport characteristics.

Effect of temperature and composition on density, viscosity and thermal conductivity of fatty acid methyl esters from soybean, castor and Jatropha curcas oils

International Nuclear Information System (INIS)

Ustra, Mara K.; Silva, Juliana R.F.; Ansolin, Marina; Balen, Manuela; Cantelli, Keli; Alkimim, Isabella P.; Mazutti, Marcio A.; Voll, Fernando A.P.; Cabral, Vladimir F.; Cardozo-Filho, Lúcio; Corazza, Marcos L.; Vladimir Oliveira, J.

2013-01-01

Highlights: ► Thermophysical properties of soybean, castor and Jatropha curcas oils and related systems. ► Effect of temperature and composition on density, viscosity and thermal conductivity of the systems studied. ► Density, dynamic viscosity and thermal conductivity data were correlated using empirical equations. -- Abstract: This work is focused on experimental determination of density, viscosity and thermal conductivity as a function of temperature and composition for fatty acid methyl esters (FAME) from soybean, castor and Jatropha curcas oils. Results show that an increase in temperature, over the range of (273 to 363) K, resulted in a decrease of all properties studied. FAME from soybean and J. curcas oils presented similar rheological behaviour, while FAME from castor oil presented higher values for density and viscosity. Density, dynamic viscosity and thermal conductivity data for all systems obtained here were correlated using empirical equations with good agreement between experimental and calculated values. Experimental data presented here may be useful as a database for specification purposes and equipment design and plant operation in the biodiesel industry

Analytical thermal modelling of multilayered active embedded chips into high density electronic board

Directory of Open Access Journals (Sweden)

Monier-Vinard Eric

2013-01-01

Full Text Available The recent Printed Wiring Board embedding technology is an attractive packaging alternative that allows a very high degree of miniaturization by stacking multiple layers of embedded chips. This disruptive technology will further increase the thermal management challenges by concentrating heat dissipation at the heart of the organic substrate structure. In order to allow the electronic designer to early analyze the limits of the power dissipation, depending on the embedded chip location inside the board, as well as the thermal interactions with other buried chips or surface mounted electronic components, an analytical thermal modelling approach was established. The presented work describes the comparison of the analytical model results with the numerical models of various embedded chips configurations. The thermal behaviour predictions of the analytical model, found to be within ±10% of relative error, demonstrate its relevance for modelling high density electronic board. Besides the approach promotes a practical solution to study the potential gain to conduct a part of heat flow from the components towards a set of localized cooled board pads.

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

Science.gov (United States)

van Lopik, Jan H.; Hartog, Niels; Zaadnoordijk, Willem Jan

2016-08-01

The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity of the injected hot water for a single injection-recovery well scheme. The proposed method was tested through numerical modeling with SEAWATv4, considering seasonal HT-ATES with four consecutive injection-storage-recovery cycles. Recovery efficiencies for the consecutive cycles were investigated for six cases with three simulated scenarios: (a) regular HT-ATES, (b) HT-ATES with density difference compensation using saline water, and (c) theoretical regular HT-ATES without free thermal convection. For the reference case, in which 80 °C water was injected into a high-permeability aquifer, regular HT-ATES had an efficiency of 0.40 after four consecutive recovery cycles. The density difference compensation method resulted in an efficiency of 0.69, approximating the theoretical case (0.76). Sensitivity analysis showed that the net efficiency increase by using the density difference compensation method instead of regular HT-ATES is greater for higher aquifer hydraulic conductivity, larger temperature difference between injection water and ambient groundwater, smaller injection volume, and larger aquifer thickness. This means that density difference compensation allows the application of HT-ATES in thicker, more permeable aquifers and with larger temperatures than would be considered for regular HT-ATES systems.

Constraining Non-thermal and Thermal properties of Dark Matter

Directory of Open Access Journals (Sweden)

Bhupal eDev

2014-05-01

Full Text Available We describe the evolution of Dark Matter (DM abundance from the very onset of its creation from inflaton decay under the assumption of an instantaneous reheating. Based on the initial conditions such as the inflaton mass and its decay branching ratio to the DM species, the reheating temperature, and the mass and interaction rate of the DM with the thermal bath, the DM particles can either thermalize (fully/partially with the primordial bath or remain non-thermal throughout their evolution history. In the thermal case, the final abundance is set by the standard freeze-out mechanism for large annihilation rates, irrespective of the initial conditions. For smaller annihilation rates, it can be set by the freeze-in mechanism which also does not depend on the initial abundance, provided it is small to begin with. For even smaller interaction rates, the DM decouples while being non-thermal, and the relic abundance will be essentially set by the initial conditions. We put model-independent constraints on the DM mass and annihilation rate from over-abundance by exactly solving the relevant Boltzmann equations, and identify the thermal freeze-out, freeze-in and non-thermal regions of the allowed parameter space. We highlight a generic fact that inflaton decay to DM inevitably leads to an overclosure of the Universe for a large range of DM parameter space, and thus poses a stringent constraint that must be taken into account while constructing models of DM. For the thermal DM region, we also show the complementary constraints from indirect DM search experiments, Big Bang Nucleosynthesis, Cosmic Microwave Background, Planck measurements, and theoretical limits due to the unitarity of S-matrix. For the non-thermal DM scenario, we show the allowed parameter space in terms of the inflaton and DM masses for a given reheating temperature, and compute the comoving free-streaming length to identify the hot, warm and cold DM regimes.

Acquisition of an Advanced Thermal Analysis andImaging System for Integration with Interdisciplinary Researchand Education in Low Density Organic Inorganic Materials

Science.gov (United States)

2017-12-02

Report: Acquisition of an Advanced Thermal Analysis and Imaging System for Integration with Interdisciplinary Research and Education in Low Density...Agreement Number: W911NF-16-1-0475 Organization: University of Texas at El Paso Title: Acquisition of an Advanced Thermal Analysis and Imaging System ...for Integration with Interdisciplinary Research and Education in Low Density Organic-Inorganic Materials Report Term: 0-Other Email: dmisra2

Analysis of aluminum base-reaction effect in density, porosity, and thermal insulation of porous fire bricks

Science.gov (United States)

Wismogroho, Agus Sukarto; Firmansyah, Trisna Bagus; Meidianto, Alwi; Widayatno, Wahyu Bambang; Amal, Muhamad Ikhlasul

2018-05-01

This paper reports the effect of aluminium corrosion reaction on the density, porosity, and thermal insulation capability of porous fire bricks. The reaction between aluminium and alkaline solution produces hydrogen and other sediment products. The test specimens of fire bricks were made from the mixture of castable cement, aluminium powder of 325 mesh in size (0, 0.1, 1, and 2 wt% with respect to castable cement), and 0.185 M KOH solution. The structural examination of the specimens shows the increase of porosity to 22.7 - 30.6% and the decrease of density in the range of 1.135-1.503 g/mL. In addition, the samples possess average pore size of 0.001-0.003 cm3 with the thermal insulation in the range of 47-78%.

RELICS of the Cosmic Dawn

Science.gov (United States)

Bradac, Marusa; Coe, Dan; Strait, Victoria; Salmon, Brett; Hoag, Austin; Bradley, Larry; Ryan, Russell; Dawson, Will; Zitrin, Adi; Jones, Christine; Sharon, Keren; Trenti, Michele; Stark, Daniel; Oesch, Pascal; Lam, Danel; Carrasco Nunez, Daniela Patricia; Paterno-Mahler, Rachel; Frye, Brenda

2018-05-01

When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and epoch of reionization? Recent observations indicate at least two critical puzzles in these studies. (1) First galaxies might have started forming stars earlier than previously thought (knowledge of stellar masses, ages, and star formation rates at this epoch requires measuring both rest-frame UV and optical light, which only Spitzer and HST can probe at z 6-11 for a large enough sample of typical galaxies. To address this cosmic puzzle, we propose to complete deep Spitzer imaging of the fields behind the 10 most powerful cosmic telescopes selected using HST, Spitzer, and Planck data from the RELICS and SRELICS programs (Reionization Lensing Cluster Survey; 41 clusters, 190 HST orbits, 440 Spitzer hours). 6 clusters out of 10 are still lacking deep data. This proposal will be a valuable Legacy complement to the existing IRAC deep surveys, and it will open up a new parameter space by probing the ordinary yet magnified population with much improved sample variance. The program will allow us to study stellar properties of a large number, 60 galaxies at z 6-11. Deep Spitzer data will be crucial to unambiguously measure their stellar properties (age, SFR, M*). Finally this proposal will establish the presence (or absence) of an unusually early established stellar population, as was recently observed in MACS1149JD at z 9. If confirmed in a larger sample, this result will require a paradigm shift in our understanding of the earliest star formation.

Molecularly Engineered Azobenzene Derivatives for High Energy Density Solid-State Solar Thermal Fuels.

Science.gov (United States)

Cho, Eugene N; Zhitomirsky, David; Han, Grace G D; Liu, Yun; Grossman, Jeffrey C

2017-03-15

Solar thermal fuels (STFs) harvest and store solar energy in a closed cycle system through conformational change of molecules and can release the energy in the form of heat on demand. With the aim of developing tunable and optimized STFs for solid-state applications, we designed three azobenzene derivatives functionalized with bulky aromatic groups (phenyl, biphenyl, and tert-butyl phenyl groups). In contrast to pristine azobenzene, which crystallizes and makes nonuniform films, the bulky azobenzene derivatives formed uniform amorphous films that can be charged and discharged with light and heat for many cycles. Thermal stability of the films, a critical metric for thermally triggerable STFs, was greatly increased by the bulky functionalization (up to 180 °C), and we were able to achieve record high energy density of 135 J/g for solid-state STFs, over a 30% improvement compared to previous solid-state reports. Furthermore, the chargeability in the solid state was improved, up to 80% charged from 40% charged in previous solid-state reports. Our results point toward molecular engineering as an effective method to increase energy storage in STFs, improve chargeability, and improve the thermal stability of the thin film.

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

NARCIS (Netherlands)

van Lopik, J.H.; Hartog, N.; Zaadnoordijk, Willem Jan

The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity

Simplified phenomenology for colored dark sectors

Energy Technology Data Exchange (ETDEWEB)

Hedri, Sonia El; Kaminska, Anna; Vries, Maikel de [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,55099 Mainz (Germany); Zurita, Jose [Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology,Engesserstraße 7, D-76128 Karlsruhe (Germany)

2017-04-20

We perform a general study of the relic density and LHC constraints on simplified models where the dark matter coannihilates with a strongly interacting particle X. In these models, the dark matter depletion is driven by the self-annihilation of X to pairs of quarks and gluons through the strong interaction. The phenomenology of these scenarios therefore only depends on the dark matter mass and the mass splitting between dark matter and X as well as the quantum numbers of X. In this paper, we consider simplified models where X can be either a scalar, a fermion or a vector, as well as a color triplet, sextet or octet. We compute the dark matter relic density constraints taking into account Sommerfeld corrections and bound state formation. Furthermore, we examine the restrictions from thermal equilibrium, the lifetime of X and the current and future LHC bounds on X pair production. All constraints are comprehensively presented in the mass splitting versus dark matter mass plane. While the relic density constraints can lead to upper bounds on the dark matter mass ranging from 2 TeV to more than 10 TeV across our models, the prospective LHC bounds range from 800 to 1500 GeV. A full coverage of the strongly coannihilating dark matter parameter space would therefore require hadron colliders with significantly higher center-of-mass energies.

Relic gravitational wave spectrum, the trans-Planckian physics and Horava-Lifshitz gravity

International Nuclear Information System (INIS)

Koh, Seoktae

2010-01-01

We calculate the spectrum of the relic gravitational wave due to the trans-Planckian effect in which the standard linear dispersion relations may be modified. Of the modified dispersion relations suggested in the literature which has investigated the trans-Planckian effect, we especially use the Corley-Jacobson dispersion relations. The Corley-Jacobson-type modified dispersion relations can be obtained from Horava-Lifshitz gravity which is non-relativistic and UV complete. Although it is not clear how the transitions from Horava-Lifshitz gravity in the UV regime to Einstein gravity in the IR limit occur, we assume that the Horava-Lifshitz gravity regime is followed by the inflationary phase in Einstein gravity.

Cosmic background radiation spectral distortion and radiative decays of relic neutral particles

International Nuclear Information System (INIS)

Berezhiani, Z.G.; Doroshkevich, A.G.; Khlopov, M.Yu.; Yurov, V.P.; Vysotskij, M.I.

1989-01-01

The recently observed excess of photons on a short wavelength side of the peak of a cosmic background radiation spectrum can be described by radiative decays of relic neutral particles. The lifetime and mass of a decaying particle must satisfy the following conditions: 2x10 9 s 14 s, 0.4 eV -9 -8x10 -8 ) μ b , and the interaction of new particles with the usual matter must be rather strong. The generalization of the standard SU(3)xSU(2)xU(1) model is presented which includes new particles with the desired properties. 18 refs.; 3 figs.; 2 tabs

Computational analysis of heat transfer, thermal stress and dislocation density during resistively Czochralski growth of germanium single crystal

Science.gov (United States)

Tavakoli, Mohammad Hossein; Renani, Elahe Kabiri; Honarmandnia, Mohtaram; Ezheiyan, Mahdi

2018-02-01

In this paper, a set of numerical simulations of fluid flow, temperature gradient, thermal stress and dislocation density for a Czochralski setup used to grow IR optical-grade Ge single crystal have been done for different stages of the growth process. A two-dimensional steady state finite element method has been applied for all calculations. The obtained numerical results reveal that the thermal field, thermal stress and dislocation structure are mainly dependent on the crystal height, heat radiation and gas flow in the growth system.

Thermal property and density measurements of samples taken from drilling cores from potential geologic media

International Nuclear Information System (INIS)

Lagedrost, J.F.; Capps, W.

1983-12-01

Density, steady-state conductivity, enthalpy, specific heat, heat capacity, thermal diffusivity and linear thermal expansion were measured on 59 materials from core drill samples of several geologic media, including rock salt, basalt, and other associated rocks from 7 potential sites for nuclear waste isolation. The measurements were conducted from or near to room temperature up to 500 0 C, or to lower temperatures if limited by specimen cracking or fracturing. Ample documentation establishes the reliability of the property measurement methods and the accuracy of the results. Thermal expansions of salts reached 2.2 to 2.8 percent at 500 0 C. Associated rocks were from 0.6 to 1.6 percent. Basalts were close to 0.3 percent at 500 0 C. Specific heats of salts varied from 0.213 to 0.233 cal g -1 C -1 , and basalts averaged 0.239 cal g -1 C -1 . Thermal conductivities of salts at 50 0 C were from 0.022 to 0.046 wcm -1 C -1 , and at 500 0 C, from 0.012 to 0.027 wcm -1 C -1 . Basalts conductivities ranged from 0.020 to 0.022 wcm -1 C -1 at 100 0 C and 0.016 to 0.018 at 500 0 C. There were no obvious conductivity trends relative to source location. Room temperature densities of salts were from 2.14 to 2.29 gcm -3 , and basalts, from 2.83 to 2.90 gcm -3 . The extreme friability of some materials made specimen fabrication difficult. 21 references, 17 figures, 28 tables

RELICS of the Cosmic Dawn

Science.gov (United States)

Bradac, Marusa; Coe, Dan; Huang, Kuang-Han; Salmon, Brett; Hoag, Austin; Bradley, Larry; Ryan, Russell; Dawson, Will; Zitrin, Adi; Jones, Christine; Sharon, Keren; Trentu, Michele; Stark, Daniel; Bouwens, Rychard; Oesch, Pascal; Lam, Daniel; Patricia Carasco Nunez, Daniela; Paterno-Mahler, Rachel; Strait, Victoria

2017-10-01

When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and epoch of reionization? Recent observations indicate at least two critical puzzles in these studies. (1) First galaxies might have started forming stars earlier than previously thought (Big Bang). (2) It is still unclear what is their star formation history and whether these galaxies can reionize the Universe. Accurate knowledge of stellar masses, ages, and star formation rates at this epoch requires measuring both rest-frame UV and optical light, which only Spitzer and HST can probe at z 6-11 for a large enough sample of typical galaxies. To address this cosmic puzzle, we propose Spitzer imaging of the fields behind the most powerful cosmic telescopes selected using HST, Spitzer, and Planck data from the RELICS and SRELICS programs (Reionization Lensing Cluster Survey; 41 clusters, 190 HST orbits, 550 Spitzer hours). This proposal will be a valuable Legacy complement to the existing IRAC deep surveys, and it will open up a new parameter space by probing the ordinary yet magnified population with much improved sample variance. The program will allow us to study stellar properties of a large number, 20 galaxies at z 6-11. Deep Spitzer data will be crucial to unambiguously measure their stellar properties (age, SFR, M*). Finally this proposal is a unique opportunity to establish the presence (or absence) of an unusually early established stellar population, as was recently observed in MACS1149JD at z 9. If confirmed, this result will require a paradigm shift in our understanding of the earliest star formation.

Thermal evolution and small scale structure of Sommerfeld enhanced dark matter

International Nuclear Information System (INIS)

Aarssen, Laura Gusta van den

2013-04-01

Although the existence of Dark Matter (DM) has been confirmed by many independent observations on various scales, its nature still remains a mystery. Leading candidates for the cold, non-baryonic DM are Weakly Interacting Massive Particles (WIMPs), that are well motivated from particle physics and naturally explain the observed relic density by their thermal production mechanism. In this thesis we focus on a particular class of WIMP models in which the Sommerfeld effect has to be taken into account. This is a quantum mechanical phenomenon that can significantly enhance the annihilation cross section in the non-relativistic limit. To describe the non-perturbative effect, we use a non-relativistic effective field theory derived from the full quantum field theory. We include a detailed discussion of the calculation for the righthanded sneutrino, which is the superpartner of the neutrino and a viable DM candidate. The Sommerfeld enhancement can have a profound influence on the thermal evolution of the DM, which can no longer be described by the standard scenario. We introduce a framework to correctly take this effect into account and apply it to a simple leptophilic DM model. A new era of annihilations can decrease the DM density even after usual freeze-out, and in some cases where the Sommerfeld enhancement is especially large, even continue until after matter-radiation equality. The effect on the asymptotic WIMP temperature, which can be directly related to a small scale cutoff in the matter density fluctuations, causes the mass of the smallest gravitationally bound objects to be larger than expected from standard calculations. Furthermore we study the effect of velocity dependent DM self-scattering in relation to the small scale structure formation. Numerical simulations of ΛCDM have shown a remarkable agreement with the large scale structure of the Universe. However, the simulations are in tension with observed abundances, inner densities and velocity profiles of

Thermal evolution and small scale structure of Sommerfeld enhanced dark matter

Energy Technology Data Exchange (ETDEWEB)

Aarssen, Laura Gusta van den

2013-04-15

Although the existence of Dark Matter (DM) has been confirmed by many independent observations on various scales, its nature still remains a mystery. Leading candidates for the cold, non-baryonic DM are Weakly Interacting Massive Particles (WIMPs), that are well motivated from particle physics and naturally explain the observed relic density by their thermal production mechanism. In this thesis we focus on a particular class of WIMP models in which the Sommerfeld effect has to be taken into account. This is a quantum mechanical phenomenon that can significantly enhance the annihilation cross section in the non-relativistic limit. To describe the non-perturbative effect, we use a non-relativistic effective field theory derived from the full quantum field theory. We include a detailed discussion of the calculation for the righthanded sneutrino, which is the superpartner of the neutrino and a viable DM candidate. The Sommerfeld enhancement can have a profound influence on the thermal evolution of the DM, which can no longer be described by the standard scenario. We introduce a framework to correctly take this effect into account and apply it to a simple leptophilic DM model. A new era of annihilations can decrease the DM density even after usual freeze-out, and in some cases where the Sommerfeld enhancement is especially large, even continue until after matter-radiation equality. The effect on the asymptotic WIMP temperature, which can be directly related to a small scale cutoff in the matter density fluctuations, causes the mass of the smallest gravitationally bound objects to be larger than expected from standard calculations. Furthermore we study the effect of velocity dependent DM self-scattering in relation to the small scale structure formation. Numerical simulations of {Lambda}CDM have shown a remarkable agreement with the large scale structure of the Universe. However, the simulations are in tension with observed abundances, inner densities and velocity

Post-inflationary thermal histories and the refractive index of relic gravitons arXiv

CERN Document Server

Giovannini, Massimo

We investigate the impact of the post-inflationary thermal histories on the cosmic graviton spectrum caused by the inflationary variation of their refractive index. Depending on the frequency band, the spectral energy distribution can be mildly red, blue or even violet. Wide portions of the parameter space lead to potentially relevant signals both in the audio range (probed by the advanced generation of terrestrial interferometers) and in the mHz band (where space-borne detectors could be operational within the incoming score year). The description of the refractive index in conformally related frames is clarified.

Light higgsino dark matter from non-thermal cosmology

Energy Technology Data Exchange (ETDEWEB)

Aparicio, Luis [ICTP,Strada Costiera 11, Trieste 34014 (Italy); Cicoli, Michele [ICTP,Strada Costiera 11, Trieste 34014 (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Dutta, Bhaskar [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy,TAMU, College Station, TX 77843-4242 (United States); Muia, Francesco [Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Quevedo, Fernando [ICTP,Strada Costiera 11, Trieste 34014 (Italy); DAMTP, Centre for Mathematical Sciences,Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2016-11-08

We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter domination prior to Big Bang nucleosynthesis. Matter domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. We show that Fermi-LAT data rule out non-thermal higgsinos with masses below 300 GeV. Future indirect dark matter searches from Fermi-LAT and CTA will be able to cover essentially the full parameter space. Contrary to the thermal case, collider signals from a 100 TeV collider could fully test the non-thermal higgsino scenario. In the second part of the paper we discuss the motivation of such non-thermal cosmology from the perspective of string theory with late-time decaying moduli for both KKLT and LVS moduli stabilisation mechanisms. We finally describe the impact of embedding higgsino dark matter in these scenarios.

Thermal and mechanical properties of injection molded recycled high density polyethylene blends with virgin isotactic polypropylene

International Nuclear Information System (INIS)

Madi, N.K.

2013-01-01

Highlights: ► Recycled high density polyethylene and isotactic polypropylene blends have been prepared by melt compounding. ► Thermal study showed that iPP is not well dispersed into the rHDPE matrix. ► Tensile testing shows that there is strong correlation between the thermal properties and the tensile behavior of rHDPE/ipp blends. - Abstract: Polymer blending has become an important field in polymer research and especially in the area of recycling. In this research the target was to reduce the polymer waste problem. Therefore, recycled high density polyethylene (rHDPE) and virgin isotactic polypropylene (vPP) blends containing upto 30 wt% of vPP have been prepared by melt compounding method using injection molding at 220 °C. The thermal properties, thermal degradation and the mechanical properties of the polymer blends were studied using differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and tensile testing method. DSC study shows that in all the blends there are two melting peaks, one around the melting temperature of rHDPE and another one around the melting point of vPP, indicating that vPP is not well dispersed into the rHDPE matrix. The changes in the heat of fusion for the rHDPE/iPP polymer blends versus vPP content suggests that incorporating vPP affects the crystallinity of the system. TGA analysis of the polymer blends shows that parts of rHDPE with 95/5 upto 80/20 of vPP are mostly stable composition which brings about valuable stabilization to the rHDPE. Tensile testing shows that there is strong correlation between the thermal properties and the tensile behavior of rHDPE/vpp blends

Late decaying 2-component dark matter scenario as an explanation of the AMS-02 positron excess

Energy Technology Data Exchange (ETDEWEB)

Buch, Jatan; Ralegankar, Pranjal; Rentala, Vikram, E-mail: jatan_buch@brown.edu, E-mail: pranjal6@illinois.edu, E-mail: rentala@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology - Bombay, Powai, Mumbai 400076 (India)

2017-10-01

The long standing anomaly in the positron flux as measured by the PAMELA and AMS-02 experiments could potentially be explained by dark matter (DM) annihilations. This scenario typically requires a large 'boost factor' to be consistent with a thermal relic dark matter candidate produced via freeze-out. However, such an explanation is disfavored by constraints from CMB observations on energy deposition during the epoch of recombination. We discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework, the heavier species is produced as a thermal relic in the early universe and decays to the lighter species over cosmological timescales. Consequently, the lighter species becomes the DM which populates the universe today. We show that annihilation of the lighter DM species with an enhanced cross-section, produced via such a non-thermal mechanism, can explain the observed AMS-02 positron flux while avoiding CMB constraints. The observed DM relic density can be correctly reproduced as well with simple s -wave annihilation cross-sections. We demonstrate that the scenario is safe from CMB constraints on late-time energy depositions during the cosmic 'dark ages'. Interestingly, structure formation constraints force us to consider small mass splittings between the two dark matter species. We explore possible cosmological and particle physics signatures in a toy model that realizes this scenario.

Late decaying 2-component dark matter scenario as an explanation of the AMS-02 positron excess

International Nuclear Information System (INIS)

Buch, Jatan; Ralegankar, Pranjal; Rentala, Vikram

2017-01-01

The long standing anomaly in the positron flux as measured by the PAMELA and AMS-02 experiments could potentially be explained by dark matter (DM) annihilations. This scenario typically requires a large 'boost factor' to be consistent with a thermal relic dark matter candidate produced via freeze-out. However, such an explanation is disfavored by constraints from CMB observations on energy deposition during the epoch of recombination. We discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework, the heavier species is produced as a thermal relic in the early universe and decays to the lighter species over cosmological timescales. Consequently, the lighter species becomes the DM which populates the universe today. We show that annihilation of the lighter DM species with an enhanced cross-section, produced via such a non-thermal mechanism, can explain the observed AMS-02 positron flux while avoiding CMB constraints. The observed DM relic density can be correctly reproduced as well with simple s -wave annihilation cross-sections. We demonstrate that the scenario is safe from CMB constraints on late-time energy depositions during the cosmic 'dark ages'. Interestingly, structure formation constraints force us to consider small mass splittings between the two dark matter species. We explore possible cosmological and particle physics signatures in a toy model that realizes this scenario.

Polycrystalline semiconductor probes for monitoring the density distribution of an intense thermal neutron flux in nuclear reactors

International Nuclear Information System (INIS)

Graul, J.; Mueller, R.G.; Wagner, E.

1975-05-01

The applicability of semiconductor detectors for high thermal neutron flux densities is theoretically estimated and experimentally examined. For good thermal stability and low radiation capture rate silicon carbide is used as semiconductor material, produced in polycristalline layers to achieve high radiation resistance. The relations between crystallinity, photoelectric sensitivity and radiation resistance are shown. The radiation resistance of polycrystalline SiC-probes is approximately 100 times greater than that of conventional single crystal radiation detectors. For thermal neutron measurement they can be used in the flux range of approx. 10 10 13 (cm -2 sec -1 ) with operation times of 1.6 a >= tsub(b,max) >= 30 d, resp. (orig.) [de

Relics, miracles and furta sacra: A contribution to the study of Serbo-Bulgarian relations in the 1230s

Directory of Open Access Journals (Sweden)

Marjanović-Dušanić Smilja

2009-01-01

Full Text Available A contribution to the study of Serbo-Bulgarian relations in the 1230s The enquiry into the cult of relics and its manifestations such as miracle working, transfer of mortal remains and the act of translatio that involves the topos of furta sacra relies on two lives of St Sava of Serbia, one penned by Domentijan (Domentianus, the other by Teodosije (Theodosius. The hagiographic episodes most relevant to this enquiry are certainly those describing Sava's stay in Tirnovo, his death (1236 and the translation of his remains to his homeland (1237. The narrative about the future saint's stay and death in Tirnovo gives conscious hints of the hero's sanctity using various hagiographic devices. Especially interesting to us is the account of the miracle Sava worked in Tirnovo while officiating the Epiphany service at the church of the Forty Martyrs. According to our analysis, the reference to the Epiphany service and the association of the miracle with that particular feast are certainly not an accident. The ideology of the Second Bulgarian Empire attached great importance to the epic victory over the Romaioi at the Battle of Tryavna in 1190, which was commemorated annually on the Day of Epiphany. The Byzantine historians Niketas Choniates and George Akropolites report that the Bulgarians seized the imperial insignia during the battle. It is irrelevant whether Sava's two hagiographers were aware of the importance of the feast or simply reiterated the well-known information about the service celebrated on that day at the church of the Forty Martyrs; what is quite certain is that the great honour of officiating the service-a celebration pregnant with symbolism-was bestowed upon the most distinguished guest and that it was then that, we believe not at all by chance, his miracle-working power was manifested in public-in front of the Bulgarian tsar, all clergy and the notables. As a natural consequence of the power of working miracles manifested in one

Journal of Astrophysics and Astronomy | Indian Academy of Sciences

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Abstract. Radio relics in galaxy clusters can be electrons accelerated at cluster merger shocks or adiabatically compressed fossil radio cocoons or dying radio galaxies. The spectral evolution of radio relics is affected by the surrounding thermal plasma. We present a low frequency study of three radio relics ...

Thermally Generated Gauge Singlet Scalars as Self-Interacting Dark Matter

CERN Document Server

McDonald, J

2002-01-01

We show that a gauge singlet scalar S with a coupling to the Higgs doublet of the form lambda_{S} S^{\\dagger}S H^{\\dagger}H and with the S mass entirely generated by the Higgs expectation value has a thermally generated relic density Omega_{S} \\approx 0.3 if m_{S} \\approx (2.9-10.5)(Omega_{S}/0.3)^{1/5}(h/0.7)^{2/5} MeV for Higgs boson masses in the range 115 GeV to 1 TeV. Remarkably, this is very similar to the range (m_{S} = (6.6-15.4)\\eta^{2/3} MeV) required in order for the self-interaction (\\eta/4)(S^{\\dagger}S)^{2} to account for self-interacting dark matter when \\eta is about 1. The corresponding coupling is lambda_{S} \\approx (2.7 \\times 10^{-10} - 3.6 \\times 10^{-9})(Omega_{S}/0.3)^{2/5}(h/0.7)^{4/5}, implying that such scalars are very weakly coupled to the Standard Model sector. More generally, for the case where the S mass is at least partially due to a bare mass term, if m_{S} \\approx 10 \\eta^{2/3} MeV, corresponding to self-interacting dark matter, then in order not to overpopulate the Universe ...

Di-photon resonance and Dark Matter as heavy pions

CERN Document Server

Redi, Michele; Tesi, Andrea; Vigiani, Elena

2016-05-13

We analyse confining gauge theories where the 750 GeV di-photon resonance is a composite techni-pion that undergoes anomalous decays into SM vectors. These scenarios naturally contain accidentally stable techni-pions Dark Matter candidates. The di-photon resonance can acquire a larger width by decaying into Dark Matter through the CP-violating $\\theta$-term of the new gauge theory reproducing the cosmological Dark Matter density as thermal relic.

Relic excavated in western India is probably of Georgian Queen Ketevan.

Science.gov (United States)

Rai, Niraj; Taher, Nizamuddin; Singh, Manvendra; Chaubey, Gyaneshwer; Jha, Aditya Nath; Singh, Lalji; Thangaraj, Kumarasamy

2014-01-01

History has well documented the execution of Queen Ketevan of Georgia by the Persian Emperor of modern day Iran. Based on historical records, in 1624 two Augustinian friars unearthed the queen's remains and one of them brought the relic to the St. Augustine convent in Goa, India. We carried out ancient DNA analysis on the human bone remains excavated from the St. Augustine convent by sequencing and genotyping of the mitochondrial DNA. The investigations of the remains revealed a unique mtDNA haplogroup U1b, which is absent in India, but present in Georgia and surrounding regions. Since our genetic analysis corroborates archaeological and literary evidence, it is likely that the excavated bone belongs to Queen Ketevan of Georgia. Copyright © 2013 Elsevier B.V. All rights reserved.

Molecular relics from chemical evolution and the origin of life

International Nuclear Information System (INIS)

Chela Flores, J.

1994-04-01

The main hypothesis proposed in this work intends to remove the difficulty that arises from the conjecture that the RNA world may have left molecular relics that may still be extant in the angiosperms. We discuss whether it is possible to envisage a possible evolutionary pathway of the RNA replicators spanning the vast time span separating the first appearance of the angiosperms, late in the Mesozoic era (the Lower Cretaceous), from the most likely suberas in which the RNA world may have occurred, namely the Hadean/Early Archean. In order to address this question we suggest that through horizontal gene transfer, as well as through a series of symbiosis of the precursor cell of the land plants, the genes of the replicases (RNA-directed RNA polymerases) associated with putative DNA-independent RNA replicators may have been transferred vertically, eventually becoming specific to the angiosperms. (author). Refs, 7 tabs

Switching of the Spin-Density-Wave in CeCoIn5 probed by Thermal Conductivity

Science.gov (United States)

Kim, Duk Y.; Lin, Shi-Zeng; Weickert, Franziska; Bauer, Eric D.; Ronning, Filip; Thompson, Joe D.; Movshovich, Roman

Unconventional superconductor CeCoIn5 orders magnetically in a spin-density-wave (SDW) in the low-temperature and high-field corner of the superconducting phase. Recent neutron scattering experiment revealed that the single-domain SDW's ordering vector Q depends strongly on the direction of the magnetic field, switching sharply as the field is rotated through the anti-nodal direction. This switching may be manifestation of a pair-density-wave (PDW) p-wave order parameter, which develops in addition to the well-established d-wave order parameter due to the SDW formation. We have investigated the hypersensitivity of the magnetic domain with a thermal conductivity measurement. The heat current (J) was applied along the [110] direction such that the Q vector is either perpendicular or parallel to J, depending on the magnetic field direction. A discontinuous change of the thermal conductivity was observed when the magnetic field is rotated around the [100] direction within 0 . 2° . The thermal conductivity with the Q parallel to the heat current (J ∥Q) is approximately 15% lager than that with the Q perpendicular to the heat current (J ⊥Q). This result is consistent with additional gapping of the nodal quasiparticle by the p-wave PDW coupled to SDW. Work at Los Alamos was performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Molecular solar thermal energy storage in photoswitch oligomers increases energy densities and storage times.

Science.gov (United States)

Mansø, Mads; Petersen, Anne Ugleholdt; Wang, Zhihang; Erhart, Paul; Nielsen, Mogens Brøndsted; Moth-Poulsen, Kasper

2018-05-16

Molecular photoswitches can be used for solar thermal energy storage by photoisomerization into high-energy, meta-stable isomers; we present a molecular design strategy leading to photoswitches with high energy densities and long storage times. High measured energy densities of up to 559 kJ kg -1 (155 Wh kg -1 ), long storage lifetimes up to 48.5 days, and high quantum yields of conversion of up to 94% per subunit are demonstrated in norbornadiene/quadricyclane (NBD/QC) photo-/thermoswitch couples incorporated into dimeric and trimeric structures. By changing the linker unit between the NBD units, we can at the same time fine-tune light-harvesting and energy densities of the dimers and trimers so that they exceed those of their monomeric analogs. These new oligomers thereby meet several of the criteria to be met for an optimum molecule to ultimately enter actual devices being able to undergo closed cycles of solar light-harvesting, energy storage, and heat release.

RELICS: Strong Lens Models for Five Galaxy Clusters from the Reionization Lensing Cluster Survey

Science.gov (United States)

Cerny, Catherine; Sharon, Keren; Andrade-Santos, Felipe; Avila, Roberto J.; Bradač, Maruša; Bradley, Larry D.; Carrasco, Daniela; Coe, Dan; Czakon, Nicole G.; Dawson, William A.; Frye, Brenda L.; Hoag, Austin; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Oesch, Pascal A.; Ogaz, Sara; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Riess, Adam G.; Rodney, Steven A.; Ryan, Russell E.; Salmon, Brett; Sendra-Server, Irene; Stark, Daniel P.; Strolger, Louis-Gregory; Trenti, Michele; Umetsu, Keiichi; Vulcani, Benedetta; Zitrin, Adi

2018-06-01

Strong gravitational lensing by galaxy clusters magnifies background galaxies, enhancing our ability to discover statistically significant samples of galaxies at {\\boldsymbol{z}}> 6, in order to constrain the high-redshift galaxy luminosity functions. Here, we present the first five lens models out of the Reionization Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell 2163, RXC J2211.7–0349, and ACT-CLJ0102–49151. The derived lensing magnification is essential for estimating the intrinsic properties of high-redshift galaxy candidates, and properly accounting for the survey volume. We report on new spectroscopic redshifts of multiply imaged lensed galaxies behind these clusters, which are used as constraints, and detail our strategy to reduce systematic uncertainties due to lack of spectroscopic information. In addition, we quantify the uncertainty on the lensing magnification due to statistical and systematic errors related to the lens modeling process, and find that in all but one cluster, the magnification is constrained to better than 20% in at least 80% of the field of view, including statistical and systematic uncertainties. The five clusters presented in this paper span the range of masses and redshifts of the clusters in the RELICS program. We find that they exhibit similar strong lensing efficiencies to the clusters targeted by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the lens models are made available to the community through the Mikulski Archive for Space Telescopes.

Thermal-Hydraulic Performance of Cross-Shaped Spiral Fuel in High-Power-Density BWRs

International Nuclear Information System (INIS)

Conboy, Thomas; Hejzlar, Pavel

2006-01-01

Power up-rating of existing nuclear reactors promises to be an area of great study for years to come. One of the major approaches to efficiently increasing power density is by way of advanced fuel design, and cross-shaped spiral-fuel has shown such potential in previous studies. Our work aims to model the thermal-hydraulic consequences of filling a BWR core with these spiral-shaped pins. The helically-wound pins have a cross-section resembling a 4-petaled flower. They fill an assembly in a tight bundle, their dimensions chosen carefully such that the petals of neighboring pins contact each other at their outer-most extent in a self-supporting lattice, absent of grid spacers. Potential advantages of this design raise much optimism from a thermal-hydraulic perspective. These spiral rods possess about 40% larger surface area than traditional rods, resulting in increased cooling and a proportional reduction in average surface heat flux. The thin petal-like extensions help by lowering thermal resistance between the hot central region of the pin and the bulk coolant flow, decreasing the maximum fuel temperature by 200 deg. C according to Finite Element (COSMOS) models. However, COSMOS models also predict a potential problem area at the 'elbow' region of two adjoining petals, where heat flux peaking is twice that along the extensions. Preliminary VIPRE models, which account only for the surface area increase, predict a 22% increase in critical power. It is also anticipated that the spiral twist would provide the flowing coolant with an additional radial velocity component, and likely promote turbulence and mixing within an assembly. These factors are expected to provide further margin for increased power density, and are currently being incorporated into the VIPRE model. The reduction in pressure drop inherent in any core without grid-spacers is also expected to be significant in aiding core stability, though this has not yet been quantified. Spiral-fuel seems to be a

Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

NARCIS (Netherlands)

Schmitz, O.; Beigman, I. L.; Vainshtein, L. A.; Schweer, B.; Kantor, M.; Pospieszczyk, A.; Xu, Y.; Krychowiak, M.; Lehnen, M.; Samm, U.; Unterberg, B.

2008-01-01

Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T-e(r, t) and electron density ne(r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed

Mirage in the sky: Nonthermal dark matter, gravitino problem, and cosmic ray anomalies

International Nuclear Information System (INIS)

Dutta, Bhaskar; Sinha, Kuver; Leblond, Louis

2009-01-01

Recent anomalies in cosmic rays could be due to dark matter annihilation in our galaxy. In order to get the required large cross section to explain the data while still obtaining the right relic density, we rely on a nonstandard thermal history between dark matter freeze out and big-bang nucleosynthesis. We show that through a reheating phase from the decay of a heavy moduli or even the gravitino, we can produce the right relic density of dark matter if its self-annihilation cross section is large enough. In addition to fitting the recent data, this scenario solves the cosmological moduli and gravitino problems. We illustrate this mechanism with a specific example in the context of U(1) B-L extended minimal supersymmetric standard model where supersymmetry is broken via mirage mediation. These string motivated models naturally contain heavy moduli decaying to the gravitino, whose subsequent decay to the LSP can reheat the Universe at a low temperature. The right-handed sneutrino and the B-L gaugino can both be viable dark matter candidates with a large cross section. They are leptophilic because of B-L charges. We also show that it is possible to distinguish the nonthermal from the thermal scenario (using Sommerfeld enhancement) in direct detection experiments for certain regions of parameter space.

Saints' Relics in Scuola di S. Giorgio degli Schiavoni: An Anti-Ottoman Pantheon

Directory of Open Access Journals (Sweden)

Ana Marinković

2018-04-01

Full Text Available The intensified military campaigns against the Ottomans in the second half of the fifteenth century palpably influenced the cult of saints venerated in Scuola di S. Giorgio degli Schiavoni, both by assimilating new saints, as well as strenghtening the existing cults through indulgences and relic acquisitions. The initial pair of patron saints – St George and St Tryphon, the city patrons of Bar and Kotor – delineated the geographical area where the majority of confraternity members originated from, that is, the Venetian Albania. The inclusion of St Jerome, the patron of Dalmatia, to the confraternal pantheon by Cardinal Bessarion's indulgence issued in 1464, in addition to rounding up the holy patronage to all the Eastern Adriatic Venetian dependencies, also marked the beginning of a strong anti-Ottoman motivation in the scuola's hagiographic horizon. The triple endowment of the Scuola in 1502 – relic acquisition, granting of indulgence, and commission of Carpaccio's monumental cycle – continued to work on the same line, and added to the practical aspect of spiritual support to the members of Venetian troops provenient of the Eastern Adriatic. However, the saints whose relics are today kept in the altar of the lower hall, including the patron saint of the Republic of Dubrovnik, point to an even wider devotional agenda, possibly arranged after the Battle of Lepanto, as the comparative analysis of the reliquaries show.   Le campagne militari contro gli Ottomani intensificatesi nella seconda metà del XV secolo influenzarono palesemente il culto dei santi venerati nella Scuola di S. Giorgio degli Schiavoni, sia attraverso l'assimilazione di nuovi santi, sia tramite il rafforzamento del culto già esistente verso le indulgenze e l'impulso all'acquisizione di reliquie. La prima coppia di santi patroni - San Giorgio e San Trifone, patroni della città di Bar e Cattaro - delimitano l'area geografica da cui proviene la maggior parte dei membri

DEFINITION OF DENSITY OF THE THERMAL STATIONARY STREAMS ON A SURFACES OF A SLEEVE OF CYLINDER COMBUSTION ENGINE BY A METHOD OF OPTIMUM FILTRATION KALMANA

Directory of Open Access Journals (Sweden)

ZARENBIN V. G.

2016-01-01

Full Text Available Problem statement. At research warmly intensity and thermal weariness of internal combustion engines (ICE the knowledge and the analysis of local temperatures and thermal streams in the basic details forming the chamber of combustion is defining. Theoretically the problem consists in the decision of the equation of heat conductivity at the set features of course of thermal processes on border of bodies. Thus there is a problem of accuracy of the decision since it depends on accuracy of the task of real boundary conditions which can be received only by means of physical experiment and corresponding metrological maintenance. Unlike temperature the thermal stream cannot be measured directly, therefore it define on a difference of temperatures (thermal gradient a method or a calorimetric method. Definition of density of streams with the help as named gauges of a thermal stream when the measured temperatures are used at the decision of a return problem of heat conductivity for chosen thermometric an element is most extended. In this case, except the requirement of one-dimensionality of distribution of temperatures, linearity and the minimum distortion of temperature fields of thermal system, there are considerable difficulties of calculation derivative of the measured temperature. To perspective it is possible to carry methods of researches which it is accepted to name cybernetic diagnostics or identification of systems. Their essence consists that the deformed information on object is compared to its mathematical model and then are defined its condition, parameters or entrance influences by minimization of square-law function are nonviscous. In work definition of density of thermal stationary streams on surfaces of a sleeve of cylinder ICE by a method of optimum filtration Kalmana and also an estimation of their reliability and accuracy is made. Possibility of application of filtration Kalmana is shown at experimental researches in ICE. The purpose

Compatibility of a dark matter discovery at XENONnT or LZ with the WIMP thermal production mechanism

Science.gov (United States)

Catena, Riccardo; Conrad, Jan; Krauss, Martin B.

2018-05-01

The discovery of dark matter (DM) at XENONnT or LZ would place constraints on DM particle mass and coupling constants. It is interesting to ask when these constraints can be compatible with the DM thermal production mechanism. We address this question within the most general set of renormalizable models that preserve Lorentz and gauge symmetry, and that extend the standard model by one DM candidate of mass mDM and one particle of mass Mmed mediating DM-quark interactions. Our analysis divides into two parts. First, we postulate that XENONnT/LZ has detected μS˜O (100 ) signal events, and use this input to calculate the DM relic density, ΩDMh2. Then, we identify the regions in the Mmed-ΩDMh2 plane which are compatible with the observed signal and with current CMB data. We find that for most of the models considered here, O (100 ) signal events at XENONnT/LZ and the DM thermal production are only compatible for resonant DM annihilations, i.e. for Mmed≃2 mDM. In this case, XENONnT/LZ would be able to simultaneously measure mDM and Mmed. We also discuss the dependence of our results on mDM, μS and the DM spin, and provide analytic expressions for annihilation cross sections and mediator decay widths for all models considered in this study.

On thermal gravitational contribution to particle production and dark matter

Directory of Open Access Journals (Sweden)

Yong Tang

2017-11-01

Full Text Available We investigate the particle production from thermal gravitational annihilation in the very early universe, which is an important contribution for particles that might not be in thermal equilibrium or/and might only have gravitational interaction, such as dark matter (DM. For particles with spin 0,1/2 and 1 we calculate the relevant cross sections through gravitational annihilation and give the analytic formulas with full mass-dependent terms. We find that DM with mass between TeV and 1016 GeV could have the relic abundance that fits the observation, with small dependence on its spin. We also discuss the effects of gravitational annihilation from inflatons. Interestingly, contributions from inflatons could be dominant and have the same power dependence on Hubble parameter of inflation as that from vacuum fluctuation. Also, fermion production from inflaton, in comparison to boson, is suppressed by its mass due to helicity selection.

Thermal evaluation by infrared measurement of implant site preparation between single and gradual drilling in artificial bone blocks of different densities.

Science.gov (United States)

Möhlhenrich, S C; Abouridouane, M; Heussen, N; Hölzle, F; Klocke, F; Modabber, A

2016-11-01

The aim of this study was to investigate the influence of bone density and drilling protocol on heat generation during implant bed preparation. Ten single and 10 gradual implant sites with diameters of 2.8, 3.5, and 4.2mm were prepared in four artificial bone blocks (density types I-IV; D1-D4). Drilling was done at constant speed (1500rpm) and with external irrigation (50ml/min); vertical speed was set at 2mm/s. An infrared camera was used for temperature measurements. Significantly higher temperatures for single drilling were found between 2.8-mm drills in D1 (P=0.0014) and D4 (P<0.0001) and between 3.5-mm drills in D3 (P=0.0087) and D4 (P<0.0001), as well as between 4.2-mm drills in D1 (P<0.0001) and D4 (P=0.0014). Low bone density led to a thermal decrease after single drilling and a thermal increase after gradual drilling. Burs with a large diameter always showed a higher temperature generation. In comparisons between 2.8- and 4.2-mm diameters for both single and gradual drills, significant differences (P<0.001) were noted for bone types II, III, and IV. Single drilling could generate more heat than traditional sequential drilling, and bone density, as well as drill diameter, influenced thermal increases. Particularly in lower-density bone, conventional sequential drilling seems to raise the temperature less. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Thermal Interaction of Closely Spaced Persons

DEFF Research Database (Denmark)

Brohus, Henrik; Nielsen, Peter V.; Tøgersen, Michael

2011-01-01

This paper presents results from a pilot study on the thermal interaction of closely spaced persons in a large enclosure. The surface temperature at different densities of persons is evaluated using a high resolution thermo vision camera in a controlled thermal environment. The corresponding ther...... thermal sensation is evaluated using questionnaires for the various densities. The results indicate that it may be acceptable to consider persons standalone, in a thermal sense, disregarding thermal interaction at usual densities in the design of large enclosures.......This paper presents results from a pilot study on the thermal interaction of closely spaced persons in a large enclosure. The surface temperature at different densities of persons is evaluated using a high resolution thermo vision camera in a controlled thermal environment. The corresponding...

Enhanced energy density and thermal conductivity in poly(fluorovinylidene-co-hexafluoropropylene) nanocomposites incorporated with boron nitride nanosheets exfoliated under assistance of hyperbranched polyethylene

Science.gov (United States)

Ye, Huijian; Lu, Tiemei; Xu, Chunfeng; Zhong, Mingqiang; Xu, Lixin

2018-03-01

Polymer dielectric film with a large dielectric constant, high energy density and enhanced thermal conductivity are of significance for the development of impulse capacitors. However, the fabrication of polymer dielectrics combining high energy density and thermal conductivity is still a challenge at the moment. Here we demonstrate the facile exfoliation of hexagonal boron nitride nanosheets (BNNSs) in common organic solvents under sonication with the assistance of hyperbranched polyethylene (HBPE). The noncovalent CH-π interactions between the nanosheets and HBPE ensure the dispersion of BNNSs in organic solvents with high concentrations, because of the highly branched chain structure of HBPE. Subsequently, the resultant BNNSs with a few defects are distributed uniformly in the poly(fluorovinylidene-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films prepared via simple solution casting. The BNNS/P(VDF-HFP) nanocomposite exhibits outstanding dielectric properties, high energy density and high thermal conductivity. The dielectric constant of the 0.5 wt% nanocomposite film is 35.5 at 100 Hz with an energy density of 5.6 J cm-3 at 325 MV m-1 and a high charge-discharge efficiency of 79% due to the depression of the charge injection and chemical species ionization in a high field. Moreover, a thermal conductivity of 1.0 wt% nanocomposite film reaches 0.91 W·m-1 · K-1, which is 3.13 times higher than that of the fluoropolymer matrix. With dipole accumulation and orientation in the interfacial zone, lightweight, flexible BNNS/P(VDF-HFP) nanocomposite films with high charge-discharge performance and thermal conductivity, exhibit promising applications in relatively high-temperature electronics and energy storage devices.

Relic gravitational waves in the accelerating Universe

International Nuclear Information System (INIS)

Zhang Yang; Yuan Yefei; Zhao Wen; Chen Yingtian

2005-01-01

Recent observations have indicated that the Universe at the present stage is in an accelerating expansion, a process that has great implications. We evaluate the spectrum of relic gravitational waves in the current accelerating Universe and find that there are new features appearing in the resulting spectrum as compared to the decelerating models. In the low-frequency range the peak of the spectrum is now located at a frequency ν E ∼ (OMEGA m /OMEGA Λ ) 1/3 ν H , where ν H is the Hubble frequency, and there appears a new segment of spectrum between ν E and ν H . In all other intervals of frequencies ≥ν H , the spectral amplitude acquires an extra factor (OMEGA m /OMEGA Λ ), due to the current acceleration; otherwise the shape of the spectrum is similar to that in the decelerating models. The recent WMAP result of CMB anisotropies is used to normalize the amplitude for gravitational waves. The slope of the power spectrum depends sensitively on the scale factor a(τ) ∝ vertical bar τ vertical bar 1+β during the inflationary stage with β = -2 for the exact de Sitter space. With increasing β, the resulting spectrum is tilted to be flatter with more power at high frequencies, and the sensitivity of the second science run of the LIGO detectors puts a restriction on the parameter β ≤ -1.8. We also give a numerical solution which confirms these features

Effect of grain alignment on interface trap density of thermally oxidized aligned-crystalline silicon films

Science.gov (United States)

Choi, Woong; Lee, Jung-Kun; Findikoglu, Alp T.

2006-12-01

The authors report studies of the effect of grain alignment on interface trap density of thermally oxidized aligned-crystalline silicon (ACSi) films by means of capacitance-voltage (C-V) measurements. C-V curves were measured on metal-oxide-semiconductor (MOS) capacitors fabricated on ⟨001⟩-oriented ACSi films on polycrystalline substrates. From high-frequency C-V curves, the authors calculated a decrease of interface trap density from 2×1012to1×1011cm-2eV-1 as the grain mosaic spread in ACSi films improved from 13.7° to 6.5°. These results demonstrate the effectiveness of grain alignment as a process technique to achieve significantly enhanced performance in small-grained (⩽1μm ) polycrystalline Si MOS-type devices.

Construction of high current density SC magnets and their thermal stability

International Nuclear Information System (INIS)

Ishibashi, K.; Katase, A.; Kobayashi, M.; Wake, M.; Suzuki, K.

1979-07-01

Pancake type solenoid magnets are constructed which have a similar cooling characteristics to a pulsed dipole magnet for a synchrotron. A metal inpregnated braided cable is used to test a long sample of the cable. The detailed performances of the magnets and cable are examined with respect to achieved fields, training effect and ac losses. The stability theories which have been proposed so far are not adequate to these high current density magnets, so that a new method is developed to estimate the magnet stability. The minimum energy of thermal disturbances (MQE) which causes a quenching is measured by experiment and is compared with the calculation. The calculated values of MQE are in good agreement with the experimental results. The performance of the pancake magnet is discussed on the basis of MQE. (author)

An intermediate framework between WIMP, FIMP, and EWIP dark matter

International Nuclear Information System (INIS)

Yaguna, Carlos E.

2012-01-01

WIMP (Weakly Interacting Massive Particle), FIMP (Feebly interacting Massive Particle) and EWIP (Extremely Weakly Interacting Particle) dark matter are different theoretical frameworks that have been postulated to explain the dark matter. In this paper we examine an intermediate scenario that combines features from these three frameworks. It consists of a weakly interacting particle — à la WIMP — that does not reach thermal equilibrium in the early Universe — à la FIMP — and whose relic density is determined by the reheating temperature of the Universe — à la EWIP. As an example, an explicit realization of this framework, based on the singlet scalar model of dark matter, is analyzed in detail. In particular, the relic density is studied as a function of the parameters of the model, and the new viable region within this intermediate scenario is determined. Finally, it is shown that this alternative framework of dark matter allows for arbitrarily heavy dark matter particles and that it suggests a connection between dark matter and inflation

High thermal stability of abrupt SiO2/GaN interface with low interface state density

Science.gov (United States)

Truyen, Nguyen Xuan; Taoka, Noriyuki; Ohta, Akio; Makihara, Katsunori; Yamada, Hisashi; Takahashi, Tokio; Ikeda, Mitsuhisa; Shimizu, Mitsuaki; Miyazaki, Seiichi

2018-04-01

The effects of postdeposition annealing (PDA) on the interface properties of a SiO2/GaN structure formed by remote oxygen plasma-enhanced chemical vapor deposition (RP-CVD) were systematically investigated. X-ray photoelectron spectroscopy clarified that PDA in the temperature range from 600 to 800 °C has almost no effects on the chemical bonding features at the SiO2/GaN interface, and that positive charges exist at the interface, the density of which can be reduced by PDA at 800 °C. The capacitance-voltage (C-V) and current density-SiO2 electric field characteristics of the GaN MOS capacitors also confirmed the reduction in interface state density (D it) and the improvement in the breakdown property of the SiO2 film after PDA at 800 °C. Consequently, a high thermal stability of the SiO2/GaN structure with a low fixed charge density and a low D it formed by RP-CVD was demonstrated. This is quite informative for realizing highly robust GaN power devices.

Thermal Performance of Low Layer Density Multilayer Insu1ation Using Liquid Nitrogen

Science.gov (United States)

Johnson, Wesley L.; Fesmire, James E.

2011-01-01

In order to support long duration cryogenic propellant storage, the Cryogenic Fluid Management (CFM) Project of the Exploration Technology Development Program (ETDP) is investigating the long duration storage propertie$ of liquid methane on the lunar surface. The Methane Lunar Surface Thermal Control (MLSTC) testing is using a tank of the approximate dimensions of the Altair ascent tanks inside of a vacuum chamber to simulate the environment in low earth orbit and on the lunar surface. The thermal performance testing of multilayer insulation (MLI) coupons that are fabricated identically to the tank applied insulation is necessary to understand the performance of the blankets and to be able to predict the performance of the insulation prior to testing. This coupon testing was completed in Cryostat-100 at the Cryogenics Test Laboratory. The results showed the properties of the insulation as a function of layer density, number of layers, and warm boundary temperature. These results aid in the understanding of the performance parameters o fMLI and help to complete the body of literature on the topic.

Numerical analysis of thermal stress and dislocation density distributions in large size multi-crystalline silicon ingots during the seeded growth process

Science.gov (United States)

Nguyen, Thi Hoai Thu; Chen, Jyh-Chen; Hu, Chieh; Chen, Chun-Hung; Huang, Yen-Hao; Lin, Huang-Wei; Yu, Andy; Hsu, Bruce

2017-06-01

In this study, a global transient numerical simulation of silicon growth from the beginning of the solidification process until the end of the cooling process is carried out modeling the growth of an 800 kg ingot in an industrial seeded directional solidification furnace. The standard furnace is modified by the addition of insulating blocks in the hot zone. The simulation results show that there is a significant decrease in the thermal stress and dislocation density in the modified model as compared to the standard one (a maximal decrease of 23% and 75% along the center line of ingot for thermal stress and dislocation density, respectively). This modification reduces the heating power consumption for solidification of the silicon melt by about 17% and shortens the growth time by about 2.5 h. Moreover, it is found that adjusting the operating conditions of modified model to obtain the lower growth rate during the early stages of the solidification process can lower dislocation density and total heater power.

X-ray fluorescence in investigations of cultural relics and archaeological finds

Energy Technology Data Exchange (ETDEWEB)

Musilek, Ladislav, E-mail: musilek@fjfi.cvut.cz [Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Brehova 7, 115 19 Praha 1 (Czech Republic); Cechak, Tomas; Trojek, Tomas [Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Brehova 7, 115 19 Praha 1 (Czech Republic)

2012-07-15

Some characteristic features of X-ray fluorescence (XRF) analysis make it an ideal method for investigations of cultural relics and archaeological finds. It has therefore become a standard method used in archaeometry. Paintings, frescos, manuscripts, pottery, metalwork, glass, and many other objects are analysed with the aim of recognising their materials, production technologies and origin, and for identifying counterfeits. This paper reviews various techniques used in XRF analyses of works of art, summarises the advantages and limitations of the method, and presents some typical examples of its use. The general review is supplemented by some techniques used and some results achieved at CTU-FNSPE in Prague. - Highlights: Black-Right-Pointing-Pointer Review of XRF analysis in archaeometry. Black-Right-Pointing-Pointer Instrumentation for XRF analysis with various sources of radiation. Black-Right-Pointing-Pointer Materials and artefacts, which can be measured and information, which can be obtained. Black-Right-Pointing-Pointer XRF analysis of artworks at the CTU Prague.

In-situ Density and Thermal Expansion Measurements of Fe and Fe-S Alloying Liquids Under Planetary Core Conditions

Science.gov (United States)

Jing, Z.; Chantel, J.; Yu, T.; Sakamaki, T.; Wang, Y.

2015-12-01

Liquid iron is likely the dominant constituent in the cores of terrestrial planets and icy satellites such as Earth, Mars, Mercury, the Moon, Ganymede, and Io. Suggested by geophysical and geochemical observations, light elements such as S, C, Si, etc., are likely present in planetary cores. These light elements can significantly reduce the density and melting temperature of the Fe cores, and hence their abundances are crucial to our understanding of the structure and thermal history of planetary cores, as well as the generation of intrinsic magnetic fields. Knowledge on the density of Fe-light element alloying liquids at high pressures is critical to place constraints on the composition of planetary cores. However, density data on liquid Fe-light element alloys at core pressures are very limited in pressure and composition and are sometimes controversial. In this study, we extend the density dataset for Fe-rich liquids by measuring the density of Fe, Fe-10wt%S, Fe-20wt%S, Fe-27wt%S, and FeS liquids using the X-ray absorption technique in a DIA-type multianvil apparatus up to 7 GPa and 2173 K. An ion chamber (1D-detector) and a CCD camera (2D-detector) were used to measure intensities of transmitted monochromatic X-rays through molten samples, with the photon energy optimized at 40 keV. The densities were then determined from the Beer-Lambert law using the mass absorption coefficients, calibrated by solid standards using X-ray diffraction. At each pressure, density measurements were conducted at a range of temperatures above the liquidus of the samples, enabling the determination of thermal expansion. Combined with our previous results on the sound velocity of Fe and Fe-S liquids at high pressures (Jing et al., 2014, Earth Planet. Sci. Lett. 396, 78-87), these data provide tight constraints on the equation of state and thermodynamic properties such as the adiabatic temperature gradient for Fe-S liquids. We will discuss these results with implications to planetary

Nonuniform multiview color texture mapping of image sequence and three-dimensional model for faded cultural relics with sift feature points

Science.gov (United States)

Li, Na; Gong, Xingyu; Li, Hongan; Jia, Pengtao

2018-01-01

For faded relics, such as Terracotta Army, the 2D-3D registration between an optical camera and point cloud model is an important part for color texture reconstruction and further applications. This paper proposes a nonuniform multiview color texture mapping for the image sequence and the three-dimensional (3D) model of point cloud collected by Handyscan3D. We first introduce nonuniform multiview calibration, including the explanation of its algorithm principle and the analysis of its advantages. We then establish transformation equations based on sift feature points for the multiview image sequence. At the same time, the selection of nonuniform multiview sift feature points is introduced in detail. Finally, the solving process of the collinear equations based on multiview perspective projection is given with three steps and the flowchart. In the experiment, this method is applied to the color reconstruction of the kneeling figurine, Tangsancai lady, and general figurine. These results demonstrate that the proposed method provides an effective support for the color reconstruction of the faded cultural relics and be able to improve the accuracy of 2D-3D registration between the image sequence and the point cloud model.

Shrines and relics between Late Antiquity and Middle Ages: Christianization of the space or sacralization of the Christianity?

Directory of Open Access Journals (Sweden)

Luigi Canetti

2002-12-01

Full Text Available This essay analyzes the importance of relics and sanctuaries against the backdrop of the sacralization of Christianity and the latter’s re-elaboration into a religious system that occurred in urban milieux in the late ancient times. The main steps of this process, which came to a climax in the 4th century, are the Christianization of time and space as well as the reinterpretation of Christ’s death in terms of a sacrifice.

Form-stable paraffin/high density polyethylene composites as solid-liquid phase change material for thermal energy storage: preparation and thermal properties

International Nuclear Information System (INIS)

Sari, Ahmet

2004-01-01

This paper deals with the preparation of paraffin/high density polyethylene (HDPE) composites as form-stable, solid-liquid phase change material (PCM) for thermal energy storage and with determination of their thermal properties. In such a composite, the paraffin (P) serves as a latent heat storage material and the HDPE acts as a supporting material, which prevents leakage of the melted paraffin because of providing structural strength. Therefore, it is named form-stable composite PCM. In this study, two kinds of paraffins with melting temperatures of 42-44 deg. C (type P1) and 56-58 deg. C (type P2) and latent heats of 192.8 and 212.4 J g -1 were used. The maximum weight percentage for both paraffin types in the PCM composites without any seepage of the paraffin in the melted state were found as high as 77%. It is observed that the paraffin is dispersed into the network of the solid HDPE by investigation of the structure of the composite PCMs using a scanning electronic microscope (SEM). The melting temperatures and latent heats of the form-stable P1/HDPE and P2/HDPE composite PCMs were determined as 37.8 and 55.7 deg. C, and 147.6 and 162.2 J g -1 , respectively, by the technique of differential scanning calorimetry (DSC). Furthermore, to improve the thermal conductivity of the form-stable P/HDPE composite PCMs, expanded and exfoliated graphite (EG) by heat treatment was added to the samples in the ratio of 3 wt.%. Thereby, the thermal conductivity was increased about 14% for the form-stable P1/HDPE and about 24% for the P2/HDPE composite PCMs. Based on the results, it is concluded that the prepared form-stable P/HDPE blends as composite type PCM have great potential for thermal energy storage applications in terms of their satisfactory thermal properties and improved thermal conductivity. Furthermore, these composite PCMs added with EG can be considered cost effective latent heat storage materials since they do not require encapsulation and extra cost to enhance

When the universe expands too fast: relentless dark matter

Science.gov (United States)

D'Eramo, Francesco; Fernandez, Nicolas; Profumo, Stefano

2017-05-01

We consider a modification to the standard cosmological history consisting of introducing a new species phi whose energy density red-shifts with the scale factor a like ρphi propto a-(4+n). For 0n>, such a red-shift is faster than radiation, hence the new species dominates the energy budget of the universe at early times while it is completely negligible at late times. If equality with the radiation energy density is achieved at low enough temperatures, dark matter can be produced as a thermal relic during the new cosmological phase. Dark matter freeze-out then occurs at higher temperatures compared to the standard case, implying that reproducing the observed abundance requires significantly larger annihilation rates. Here, we point out a completely new phenomenon, which we refer to as relentless dark matter: for large enough n, unlike the standard case where annihilation ends shortly after the departure from thermal equilibrium, dark matter particles keep annihilating long after leaving chemical equilibrium, with a significant depletion of the final relic abundance. Relentless annihilation occurs for n >= 2 and n >= 4 for s-wave and p-wave annihilation, respectively, and it thus occurs in well motivated scenarios such as a quintessence with a kination phase. We discuss a few microscopic realizations for the new cosmological component and highlight the phenomenological consequences of our calculations for dark matter searches.

Thermal gravitational waves in accelerating universe

Directory of Open Access Journals (Sweden)

B Ghayour

2013-10-01

Full Text Available Gravitational waves are considered in thermal vacuum state. The amplitude and spectral energy density of gravitational waves are found enhanced in thermal vacuum state compared to its zero temperature counterpart. Therefore, the allowed amount of enhancement depends on the upper bound of WMAP-5 and WMAP-7 for the amplitude and spectral energy density of gravitational waves. The enhancement of amplitude and spectral energy density of the waves in thermal vacuum state is consistent with current accelerating phase of the universe. The enhancement feature of amplitude and spectral energy density of the waves is independent of the expansion model of the universe and hence the thermal effect accounts for it. Therefore, existence of thermal gravitational waves is not ruled out

The relic Criollo cacao in Belize- genetic diversity and relationship with Trinitario and other cacao clones held in the International Cocoa Genebank, Trinidad

Science.gov (United States)

Cacao (Theobroma cacao L.) is native to the South American rainforest but it was domesticated in Mesoamerica. The relic Criollo cocoa in Belize has been well known in the premium chocolate market for its high-quality. Knowledge of genetic diversity in this variety is essential for efficient conserva...

A New Method of Gold Foil Damage Detection in Stone Carving Relics Based on Multi-Temporal 3D LiDAR Point Clouds

Directory of Open Access Journals (Sweden)

Miaole Hou

2016-05-01

Full Text Available The timely detection of gold foil damage in gold-overlaid stone carvings and the associated maintenance of these relics pose several challenges to both the research and heritage protection communities internationally. This paper presents a new method for detecting gold foil damage by making use of multi-temporal 3D LiDAR point clouds. By analyzing the errors involved in the detection process, a formula is developed for calculation of the damage detection threshold. An improved division method for the linear octree that only allocates memory to the non-blank nodes, is proposed, which improves storage and retrieval efficiency for the point clouds. Meanwhile, the damage-occurrence regions are determined according to Hausdorff distances. Using a triangular mesh, damaged regions can be identified and measured in order to determine the relic’s total damaged area. Results demonstrate that this method can effectively detect gold foil damage in stone carvings. The identified surface area of damaged regions can provide the information needed for subsequent restoration and protection of relics of this type.

Path integral density matrix dynamics: a method for calculating time-dependent properties in thermal adiabatic and non-adiabatic systems.

Science.gov (United States)

Habershon, Scott

2013-09-14

We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density matrix; subsequent evolution of this density matrix is equivalent to solution of the time-dependent Schrödinger equation, which we perform using a linear expansion of Gaussian wavepacket basis functions which evolve according to simple classical-like trajectories. Overall, this methodology represents a formally exact approach for calculating time-dependent quantum properties; by introducing approximations into both the imaginary-time and real-time propagations, this approach can be adapted for complex many-particle systems interacting through arbitrary potentials. We demonstrate this method for the spin Boson model, where we find good agreement with numerically exact calculations. We also discuss future directions of improvement for our approach with a view to improving accuracy and efficiency.

Path integral density matrix dynamics: A method for calculating time-dependent properties in thermal adiabatic and non-adiabatic systems

International Nuclear Information System (INIS)

Habershon, Scott

2013-01-01

We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density matrix; subsequent evolution of this density matrix is equivalent to solution of the time-dependent Schrödinger equation, which we perform using a linear expansion of Gaussian wavepacket basis functions which evolve according to simple classical-like trajectories. Overall, this methodology represents a formally exact approach for calculating time-dependent quantum properties; by introducing approximations into both the imaginary-time and real-time propagations, this approach can be adapted for complex many-particle systems interacting through arbitrary potentials. We demonstrate this method for the spin Boson model, where we find good agreement with numerically exact calculations. We also discuss future directions of improvement for our approach with a view to improving accuracy and efficiency

Density of thermal vacancies in γ-Ti-Al-M, M = Si, Cr, Nb, Mo, Ta or W

International Nuclear Information System (INIS)

Woodward, C.; Kajihara, S.

1999-01-01

Modifications to alloy chemistry are often used to tailor the intrinsic flow behavior of structural materials. Models of creep in intermetallic alloys must account for the influence of chemistry on the available intrinsic creep mechanisms. As in simple metals the presence of vacancies strongly influences bulk diffusion processes in these materials. Limiting the density of constitutional and thermal vacancies by alloying may produce materials with enhanced creep properties. The energy of intrinsic and substitutional point defects in L1 0 TiAl is calculated within a first principles, local density functional theory framework. Relaxed structures and energies for vacancies, antisites and solid solutions are calculated using a plane-wave-pseudopotential method. Calculated defect energies are used within a canonical ensemble formalism to estimate the point defect densities as a function of temperature and composition. The density of vacancies is found to be sensitive to the underlying stoichiometry of TiAl. The dependence of the vacancy concentration for solid solutions of Si, Cr, Nb, Mo, Ta and W is also predicted

Electrically and Thermally Conductive Low Density Polyethylene-Based Nanocomposites Reinforced by MWCNT or Hybrid MWCNT/Graphene Nanoplatelets with Improved Thermo-Oxidative Stability

OpenAIRE

Sandra Paszkiewicz; Anna Szymczyk; Daria Pawlikowska; Jan Subocz; Marek Zenker; Roman Masztak

2018-01-01

In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along wi...

Solid state thermal rectifier

Science.gov (United States)

None

2016-07-05

Thermal rectifiers using linear nanostructures as core thermal conductors have been fabricated. A high mass density material is added preferentially to one end of the nanostructures to produce an axially non-uniform mass distribution. The resulting nanoscale system conducts heat asymmetrically with greatest heat flow in the direction of decreasing mass density. Thermal rectification has been demonstrated for linear nanostructures that are electrical insulators, such as boron nitride nanotubes, and for nanostructures that are conductive, such as carbon nanotubes.

The determination of self-powered neutron detector sensitivity on thermal and epithermal neutron flux densities

International Nuclear Information System (INIS)

Erben, O.

1980-01-01

The coefficients of thermal and epithermal neutron flux density depression and self-shielding for the SPN detectors with vanadium, rhodium, silver and cobalt emitters are presented, (for cobalt SPN detectors the functions describing the absorbtion of neutrons along the emitter cross-section are also shown). Using these coefficients and previously published beta particle escape efficiencies, sensitivities are determined for the principal types of detectors produced by Les Cables de Lyon and SODERN companies. The experiments and their results verifying the validity of the theoretical work are described. (author)

Flooded Dark Matter and S level rise

International Nuclear Information System (INIS)

Randall, Lisa; Scholtz, Jakub; Unwin, James

2016-01-01

Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as “Maximum Baroqueness”. We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant

Flooded Dark Matter and S level rise

Energy Technology Data Exchange (ETDEWEB)

Randall, Lisa; Scholtz, Jakub [Department of Physics, Harvard University,Cambridge, MA 02138 (United States); Unwin, James [Department of Physics, University of Illinois at Chicago,Chicago, IL 60607 (United States)

2016-03-03

Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as “Maximum Baroqueness”. We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant

Specific effect of the linear charge density of the acid polysaccharide on thermal aggregation/ disaggregation processes in complex carrageenan/lysozyme systems

NARCIS (Netherlands)

Antonov, Y.; Zhuravleva, I.; Cardinaels, R.M.; Moldenaers, P.

2017-01-01

We study thermal aggregation and disaggregation processes in complex carrageenan/lysozyme systems with a different linear charge density of the sulphated polysaccharide. To this end, we determine the temperature dependency of the turbidity and the intensity size distribution functions in complex

Thermal dark matter through the Dirac neutrino portal

Science.gov (United States)

Batell, Brian; Han, Tao; McKeen, David; Haghi, Barmak Shams Es

2018-04-01

We study a simple model of thermal dark matter annihilating to standard model neutrinos via the neutrino portal. A (pseudo-)Dirac sterile neutrino serves as a mediator between the visible and the dark sectors, while an approximate lepton number symmetry allows for a large neutrino Yukawa coupling and, in turn, efficient dark matter annihilation. The dark sector consists of two particles, a Dirac fermion and complex scalar, charged under a symmetry that ensures the stability of the dark matter. A generic prediction of the model is a sterile neutrino with a large active-sterile mixing angle that decays primarily invisibly. We derive existing constraints and future projections from direct detection experiments, colliders, rare meson and tau decays, electroweak precision tests, and small scale structure observations. Along with these phenomenological tests, we investigate the consequences of perturbativity and scalar mass fine tuning on the model parameter space. A simple, conservative scheme to confront the various tests with the thermal relic target is outlined, and we demonstrate that much of the cosmologically-motivated parameter space is already constrained. We also identify new probes of this scenario such as multibody kaon decays and Drell-Yan production of W bosons at the LHC.

Probing neutrino dark energy with extremely high-energy cosmic neutrinos

International Nuclear Information System (INIS)

Ringwald, A.; Schrempp, L.

2006-06-01

Recently, a new non-Standard Model neutrino interaction mediated by a light scalar field was proposed, which renders the big-bang relic neutrinos of the cosmic neutrino background a natural dark energy candidate, the so-called Neutrino Dark Energy. As a further consequence of this interaction, the neutrino masses become functions of the neutrino energy densities and are thus promoted to dynamical, time/redshift dependent quantities. Such a possible neutrino mass variation introduces a redshift dependence into the resonance energies associated with the annihilation of extremely high-energy cosmic neutrinos on relic anti-neutrinos and vice versa into Z-bosons. In general, this annihilation process is expected to lead to sizeable absorption dips in the spectra to be observed on earth by neutrino observatories operating in the relevant energy region above 10 13 GeV. In our analysis, we contrast the characteristic absorption features produced by constant and varying neutrino masses, including all thermal background effects caused by the relic neutrino motion. We firstly consider neutrinos from astrophysical sources and secondly neutrinos originating from the decomposition of topological defects using the appropriate fragmentation functions. On the one hand, independent of the nature of neutrino masses, our results illustrate the discovery potential for the cosmic neutrino background by means of relic neutrino absorption spectroscopy. On the other hand, they allow to estimate the prospects for testing its possible interpretation as source of Neutrino Dark Energy within the next decade by the neutrino observatories ANITA and LOFAR. (Orig.)

Dark Radiation or Warm Dark Matter from long lived particle decays in the light of Planck

International Nuclear Information System (INIS)

Di Bari, Pasquale; King, Stephen F.; Merle, Alexander

2013-01-01

Although Planck data supports the standard ΛCDM model, it still allows for the presence of Dark Radiation corresponding up to about half an extra standard neutrino species. We propose a scenario for obtaining a fractional “effective neutrino species” from a thermally produced particle which decays into a much lighter stable relic plus standard fermions. At lifetimes much longer than ∼1 s, both the relic particles and the non-thermal neutrino component contribute to Dark Radiation. By increasing the stable-to-unstable particle mass ratio, the relic particle no longer acts as Dark Radiation but instead becomes a candidate for Warm Dark Matter with mass O(1 keV–100 GeV). In both cases it is possible to address the lithium problem

Experimental study on density, thermal conductivity, specific heat, and viscosity of water-ethylene glycol mixture dispersed with carbon nanotubes

Directory of Open Access Journals (Sweden)

Ganeshkumar Jayabalan

2017-01-01

Full Text Available This article presents the effect of adding multi wall carbon nanotubes (MWCNT in water – ethylene glycol mixture on density and various thermophysical properties such as thermal conductivity, specific heat and viscosity. Density of nanofluids was measured using standard volumetric flask method and the data showed a good agreement with the mixing theory. The maximum thermal conductivity enhancement of 11 % was noticed for the nanofluids with 0.9 wt. %. Due to lower specific heat of the MWCNT, the specific heat of the nanofluids decreased in proportion with the MWCNT concentration. The rheological analysis showed that the transition region from shear thinning to Newtonian extended to the higher shear stress range compared to that of base fluids. Viscosity ratio of the nanofluids augmented anomalously with respect to increase in temperature and about 2.25 fold increase was observed in the temperature range of 30 – 40 ˚C. The modified model of Maron and Pierce predicted the viscosity of the nanofluids with the inclusion of effect of aspect ratio of MWCNT and nanoparticle aggregates.

Study on Tensile Fatigue Behavior of Thermal Butt Fusion in Safety Class III High-Density Polyethylene Buried Piping in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Sung; Lee, Young Ju [Sunchon National University, Suncheon (Korea, Republic of); Oh, Young Jin [KEPCO E and C, Yongin (Korea, Republic of)

2015-01-15

High-density polyethylene (HDPE) piping, which has recently been applied to safety class III piping in nuclear power plants, can be butt-joined through the thermal fusion process, which heats two fused surfaces and then subject to axial pressure. The thermal fusion process generates bead shapes on the butt fusion. The stress concentrations caused by the bead shapes may reduce the fatigue lifetime. Thus, investigating the effect of the thermal butt fusion beads on fatigue behavior is necessary. This study examined the fatigue behavior of thermal butt fusion via a tensile fatigue test under stress-controlled conditions using finite element elastic stress analysis. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low-cycle fatigue region while having a negligible effect in the medium- and high-cycle fatigue regions.

Study on Tensile Fatigue Behavior of Thermal Butt Fusion in Safety Class III High-Density Polyethylene Buried Piping in Nuclear Power Plants

International Nuclear Information System (INIS)

Kim, Jong Sung; Lee, Young Ju; Oh, Young Jin

2015-01-01

High-density polyethylene (HDPE) piping, which has recently been applied to safety class III piping in nuclear power plants, can be butt-joined through the thermal fusion process, which heats two fused surfaces and then subject to axial pressure. The thermal fusion process generates bead shapes on the butt fusion. The stress concentrations caused by the bead shapes may reduce the fatigue lifetime. Thus, investigating the effect of the thermal butt fusion beads on fatigue behavior is necessary. This study examined the fatigue behavior of thermal butt fusion via a tensile fatigue test under stress-controlled conditions using finite element elastic stress analysis. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low-cycle fatigue region while having a negligible effect in the medium- and high-cycle fatigue regions

Quantum thermal rectification to design thermal diodes and transistors

Energy Technology Data Exchange (ETDEWEB)

Joulain, Karl; Ezzahri, Younes; Ordonez-Miranda, Jose [Univ. de Poitiers, Futuroscope Chasseneuil (France). Inst. Pprime, CNRS

2017-05-01

We study in this article how heat can be exchanged between two-level systems, each of them being coupled to a thermal reservoir. Calculations are performed solving a master equation for the density matrix using the Born-Markov approximation. We analyse the conditions for which a thermal diode and a thermal transistor can be obtained as well as their optimisation.

Life of saint Spiridon and history on relic to the bishop of Tremithus

Directory of Open Access Journals (Sweden)

Adam Magruk

2015-11-01

Full Text Available In the last few years Saint Spyridon – the great hierarch of Greek Orthodox Church, is becoming increasingly known, glorified and praised by Orthodox Christians from all over the world including slavic territories. In Russia, for instance, St Spyridon is honored on a par with St Nikolaos the Wonderworker. Therefore, his biography is truly admirable, e.g. occurrences before the ordination to the priesthood and even more interestingly facts after he was made Bishop of Trimythous. St Spyridon participated in the sessions of the Firts Ecumenical Council, where he played a significant and remarkable role. Special attention deserve also the history of St Spyridon’s relics, which repose on the Greek island of Corfu to this day as well as his miraculous right hand returned to Orthodox Greeks by Catholic Church after c. 800 years.

Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

Energy Technology Data Exchange (ETDEWEB)

Vo, Truong Quoc; Kim, BoHung, E-mail: muratbarisik@iyte.edu.tr, E-mail: bohungk@ulsan.ac.kr [School of Mechanical Engineering, University of Ulsan, Daehak-ro 93, Namgu, Ulsan 680-749 (Korea, Republic of); Barisik, Murat, E-mail: muratbarisik@iyte.edu.tr, E-mail: bohungk@ulsan.ac.kr [Department of Mechanical Engineering, Izmir Institute of Technology, Urla, Izmir 35430 (Turkey)

2016-05-21

This study focuses on the proper characterization of temperature profiles across grain boundaries (GBs) in order to calculate the correct interfacial thermal resistance (ITR) and reveal the influence of GB geometries onto thermal transport. The solid-solid interfaces resulting from the orientation difference between the (001), (011), and (111) copper surfaces were investigated. Temperature discontinuities were observed at the boundary of grains due to the phonon mismatch, phonon backscattering, and atomic forces between dissimilar structures at the GBs. We observed that the temperature decreases gradually in the GB area rather than a sharp drop at the interface. As a result, three distinct temperature gradients developed at the GB which were different than the one observed in the bulk solid. This behavior extends a couple molecular diameters into both sides of the interface where we defined a thickness at GB based on the measured temperature profiles for characterization. Results showed dependence on the selection of the bin size used to average the temperature data from the molecular dynamics system. The bin size on the order of the crystal layer spacing was found to present an accurate temperature profile through the GB. We further calculated the GB thickness of various cases by using potential energy (PE) distributions which showed agreement with direct measurements from the temperature profile and validated the proper binning. The variation of grain crystal orientation developed different molecular densities which were characterized by the average atomic surface density (ASD) definition. Our results revealed that the ASD is the primary factor affecting the structural disorders and heat transfer at the solid-solid interfaces. Using a system in which the planes are highly close-packed can enhance the probability of interactions and the degree of overlap between vibrational density of states (VDOS) of atoms forming at interfaces, leading to a reduced ITR. Thus, an

When the universe expands too fast: relentless dark matter

Energy Technology Data Exchange (ETDEWEB)

D' Eramo, Francesco; Fernandez, Nicolas; Profumo, Stefano, E-mail: fderamo@ucsc.edu, E-mail: nfernan2@ucsc.edu, E-mail: profumo@ucsc.edu [Department of Physics, University of California Santa Cruz, 1156 High St., Santa Cruz, CA 95064 (United States)

2017-05-01

We consider a modification to the standard cosmological history consisting of introducing a new species φ whose energy density red-shifts with the scale factor a like ρ{sub φ} ∝ a {sup −(4+} {sup n} {sup )}. For 0 n >, such a red-shift is faster than radiation, hence the new species dominates the energy budget of the universe at early times while it is completely negligible at late times. If equality with the radiation energy density is achieved at low enough temperatures, dark matter can be produced as a thermal relic during the new cosmological phase. Dark matter freeze-out then occurs at higher temperatures compared to the standard case, implying that reproducing the observed abundance requires significantly larger annihilation rates. Here, we point out a completely new phenomenon, which we refer to as relentless dark matter: for large enough n , unlike the standard case where annihilation ends shortly after the departure from thermal equilibrium, dark matter particles keep annihilating long after leaving chemical equilibrium, with a significant depletion of the final relic abundance. Relentless annihilation occurs for n ≥ 2 and n ≥ 4 for s -wave and p -wave annihilation, respectively, and it thus occurs in well motivated scenarios such as a quintessence with a kination phase. We discuss a few microscopic realizations for the new cosmological component and highlight the phenomenological consequences of our calculations for dark matter searches.

Application of Thermal Network Model to Transient Thermal Analysis of Power Electronic Package Substrate

Directory of Open Access Journals (Sweden)

Masaru Ishizuka

2011-01-01

Full Text Available In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed.

Volume and density changes of biological fluids with temperature

Science.gov (United States)

Hinghofer-Szalkay, H.

1985-01-01

The thermal expansion of human blood, plasma, ultrafiltrate, and erythrocycte concentration at temperatures in the range of 4-48 C is studied. The mechanical oscillator technique which has an accuracy of 1 x 10 to the -5 th g/ml is utilized to measure fluid density. The relationship between thermal expansion, density, and temperature is analyzed. The study reveals that: (1) thermal expansion increases with increasing temperature; (2) the magnitude of the increase declines with increasing temperature; (3) thermal expansion increases with density at temperatures below 40 C; and (4) the thermal expansion of intracellular fluid is greater than that of extracellular fluid in the temperature range of 4-10 C, but it is equal at temperatures greater than or equal to 40 C.

Transport tensors in perfectly aligned low-density fluids: Self-diffusion and thermal conductivity

International Nuclear Information System (INIS)

Singh, G. S.; Kumar, B.

2001-01-01

The modified Taxman equation for the kinetic theory of low-density fluids composed of rigid aspherical molecules possessing internal degrees of freedom is generalized to obtain the transport tensors in a fluid of aligned molecules. The theory takes care of the shape of the particles exactly but the solution has been obtained only for the case of perfectly aligned hard spheroids within the framework of the first Sonine polynomial approximation. The expressions for the thermal-conductivity components have been obtained for the first time whereas the self-diffusion components obtained here turn out to be exactly the same as those derived by Kumar and Masters [Mol. Phys. >81, 491 (1994)] through the solution of the Lorentz-Boltzmann equation. All our expressions yield correct results in the hard-sphere limit

Role of exact exchange in thermally-assisted-occupation density functional theory: A proposal of new hybrid schemes.

Science.gov (United States)

Chai, Jeng-Da

2017-01-28

We propose hybrid schemes incorporating exact exchange into thermally assisted-occupation-density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] for an improved description of nonlocal exchange effects. With a few simple modifications, global and range-separated hybrid functionals in Kohn-Sham density functional theory (KS-DFT) can be combined seamlessly with TAO-DFT. In comparison with global hybrid functionals in KS-DFT, the resulting global hybrid functionals in TAO-DFT yield promising performance for systems with strong static correlation effects (e.g., the dissociation of H 2 and N 2 , twisted ethylene, and electronic properties of linear acenes), while maintaining similar performance for systems without strong static correlation effects. Besides, a reasonably accurate description of noncovalent interactions can be efficiently achieved through the inclusion of dispersion corrections in hybrid TAO-DFT. Relative to semilocal density functionals in TAO-DFT, global hybrid functionals in TAO-DFT are generally superior in performance for a wide range of applications, such as thermochemistry, kinetics, reaction energies, and optimized geometries.

Review of the analysis of relics associated with the HMAS Sydney II

Energy Technology Data Exchange (ETDEWEB)

Treasure, Alana, E-mail: alana.treasure@awm.gov.a [Collection Services, Australian War Memorial, Canberra (Australia); Bailey, George; Challenor, Catherine [Collection Services, Australian War Memorial, Canberra (Australia); Otieno-Alego, Vincent [Forensic and Data Centres, Australian Federal Police, Canberra (Australia); Creagh, Dudley [Faculty of Applied Science, University of Canberra, Canberra (Australia)

2010-07-21

The 1941 sinking of the HMAS Sydney II in action with the German raider KSN Kormoran off the coast of Western Australia has been a source of mystery and speculation for more than 60 years. HMAS Sydney II was lost with all hands. The largest item of flotsam found in the vicinity was a Carley float, which was riddled with holes some of which contained small metallic items. The float was subjected to various physical and elemental examination methods in 1992 in an attempt to determine what may have happened. Three months after sinking, the unidentified body of a man washed ashore at Christmas Island in another Carley float. Relics found in his unmarked grave in 2006 included several degraded and corroded press-studs, some containing fragments of fabric. A metal fragment was recovered from the man's skull. XRF, SEM-EDS, Raman and FTIR spectroscopy, and X-ray tomography analysis of these items was conducted in an attempt to determine what link the sailor may have to the HMAS Sydney II.

Coupled neutronics and thermal hydraulics of high density cores for FRM II

Energy Technology Data Exchange (ETDEWEB)

Breitkreutz, Harald

2011-03-04

% enriched disperse UMo core with different densities at two reactor power levels, and two 40% enriched monolithic UMo cores, one with flat plates and one with plates that have a thickness gradient. Again, two different power levels were regarded. To estimate the uncertainty of the performed calculations, a sensitivity analysis was conducted. This includes results of neutronics, burn-up and thermal hydraulics. The identified uncertainties are generally quite small. (orig.)

Coupled neutronics and thermal hydraulics of high density cores for FRM II

International Nuclear Information System (INIS)

Breitkreutz, Harald

2011-01-01

different densities at two reactor power levels, and two 40% enriched monolithic UMo cores, one with flat plates and one with plates that have a thickness gradient. Again, two different power levels were regarded. To estimate the uncertainty of the performed calculations, a sensitivity analysis was conducted. This includes results of neutronics, burn-up and thermal hydraulics. The identified uncertainties are generally quite small. (orig.)

Hidden charged dark matter

International Nuclear Information System (INIS)

Feng, Jonathan L.; Kaplinghat, Manoj; Tu, Huitzu; Yu, Hai-Bo

2009-01-01

Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact (\\rm U)(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many novel properties not shared by neutral dark matter: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may reduce its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially impacting properties of the Bullet Cluster and the observed morphology of galactic halos. We analyze all of these effects in a WIMPless model in which the hidden sector is a simplified version of the minimal supersymmetric standard model and the dark matter is a hidden sector stau. We find that charged hidden dark matter is viable and consistent with the correct relic density for reasonable model parameters and dark matter masses in the range 1 GeV ∼ X ∼< 10 TeV. At the same time, in the preferred range of parameters, this model predicts cores in the dark matter halos of small galaxies and other halo properties that may be within the reach of future observations. These models therefore provide a viable and well-motivated framework for collisional dark matter with Sommerfeld enhancement, with novel implications for astrophysics and dark matter searches

Electrically and Thermally Conductive Low Density Polyethylene-Based Nanocomposites Reinforced by MWCNT or Hybrid MWCNT/Graphene Nanoplatelets with Improved Thermo-Oxidative Stability

Directory of Open Access Journals (Sweden)

Sandra Paszkiewicz

2018-04-01

Full Text Available In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE/multi-walled carbon nanotubes (MWCNTs + graphene nanoplatelets (GNPs hybrid nanocomposites (HNCs have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM. The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures.

Electrically and Thermally Conductive Low Density Polyethylene-Based Nanocomposites Reinforced by MWCNT or Hybrid MWCNT/Graphene Nanoplatelets with Improved Thermo-Oxidative Stability.

Science.gov (United States)

Paszkiewicz, Sandra; Szymczyk, Anna; Pawlikowska, Daria; Subocz, Jan; Zenker, Marek; Masztak, Roman

2018-04-22

In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures.

Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

International Nuclear Information System (INIS)

Schmitz, O; Schweer, B; Pospieszczyk, A; Lehnen, M; Samm, U; Unterberg, B; Beigman, I L; Vainshtein, L A; Kantor, M; Xu, Y; Krychowiak, M

2008-01-01

Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T e (r, t) and electron density n e (r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed as well as the major factors for the measurement's accuracy are evaluated. On the experimental side, the hardware specifications are described and the impact of the beam atoms on the local plasma parameters is shown to be negligible. On the modeling side the collisional-radiative model (CRM) applied to infer n e and T e from the measured He line intensities is evaluated. The role of proton and deuteron collisions and of charge exchange processes is studied with a new CRM and the impact of these so far neglected processes appears to be of minor importance. Direct comparison to Thomson scattering and fast triple probe data showed that for high densities n e > 3.5 x 10 19 m -3 the T e values deduced with the established CRM are too low. However, the new atomic data set implemented in the new CRM leads in general to higher T e values. This allows us to specify the range of reliable application of BES on thermal helium to a range of 2.0 x 10 18 e 19 m -3 and 10 eV e < 250 eV which can be extended by routine application of the new CRM.

Density limits in Tokamaks

International Nuclear Information System (INIS)

Tendler, M.

1984-06-01

The energy loss from a tokamak plasma due to neutral hydrogen radiation and recycling is of great importance for the energy balance at the periphery. It is shown that the requirement for thermal equilibrium implies a constraint on the maximum attainable edge density. The relation to other density limits is discussed. The average plasma density is shown to be a strong function of the refuelling deposition profile. (author)

Big-bang nucleosynthesis and the relic abundance of dark matter in a stau-neutralino coannihilation scenario

International Nuclear Information System (INIS)

Jittoh, Toshifumi; Koike, Masafumi; Sato, Joe; Yamanaka, Masato; Kohri, Kazunori; Shimomura, Takashi

2008-01-01

A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of 7 Li between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of 7 Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.

Equivalent Energy Density concept: A preliminary reexamination of a technique for equating thermal loads

International Nuclear Information System (INIS)

Ryder, E.E.

1992-08-01

Historical and projected inventories of spent fuel from commercial light-water nuclear reactors exhibit diverse decay characteristics and ages. This report summarizes a preliminary reexamination of a method for determining equivalent thermal loads for the range of spent fuel expected at a potential underground repository. The method, known at the Equivalent Energy Density (EED) concept, bases its equivalence criteria on the assumption that a given waste will produce worst-case thermomechanical effects equal to worst-case thermomechanical effects produced by a baseline waste, provided that the thermal energy deposited in the host rock over a specified deposition period is the same for both waste descriptions. To test this assumption, temperature histories at representative locations within the host rock were calculated using layouts defined by the EED concept and four deposition periods (20, 50, 100, and 300 years). It was found that the peak temperatures at near-field locations were best matched by the shorter deposition periods of 20 and 50 years. However, due to the sensitivity of the near-field environment to short-term canister-to-canister interactions, caution,should be used when choosing a near-field deposition period. At the location chosen to represent the far-field, a 300-year deposition period provided reasonable correspondence of peak temperature responses for all waste descriptions examined

The dependence of critical current density of GdFeCo layer on composition of thermally assisted STT-RAM

Science.gov (United States)

Dai, B.; Zhu, J.; Liu, K.; Yang, L.; Han, J.

2017-07-01

Amorphous rare earth-transitional metal (RETM) GdFeCo memory layer with RE- and TM-rich compositions was fabricated in stacks of GdFeCo (10 nm)/Cu (3 nm)/[Co(0.2 nm)/Pd(0.4 nm)]6. Their magnetic properties and spin transfer torque (STT) switching of magnetization were investigated. The maximum magneto-resistance (MR) was around 0.24% for the TM-rich Gd21.4 (Fe90Co10)78.6 memory layer and was -0.03% for the RE-rich Gd29.0 (Fe90Co10)71.0 memory layer. The critical current densities Jc to switch the GdFeCo memory layers are in the range of 1.4 × 107 A/cm2-4.5 × 107 A/cm2. The dependence of critical current density Jc and effective anisotropy constant Keff on Gd composition were also investigated. Both Jc and Keff have maximum values in the Gd composition range from 21-29 at.%, suitable for thermally assisted STT-RAM for storage density exceeding Gb/inch2.

The evolution of solid density within a thermal explosion II. Dynamic proton radiography of cracking and solid consumption by burning

International Nuclear Information System (INIS)

Smilowitz, L.; Henson, B. F.; Romero, J. J.; Asay, B. W.; Saunders, A.; Merrill, F. E.; Morris, C. L.; Kwiatkowski, K.; Grim, G.; Mariam, F.; Schwartz, C. L.; Hogan, G.; Nedrow, P.; Murray, M. M.; Thompson, T. N.; Espinoza, C.; Lewis, D.; Bainbridge, J.; McNeil, W.; Rightley, P.

2012-01-01

We report proton transmission images obtained subsequent to the laser assisted thermal ignition of a sample of PBX 9501 (a plastic bonded formulation of the explosive nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)). We describe the laser assisted thermal ignition technique as a means to synchronize a non-linear thermal ignition event while preserving the subsequent post-ignition behavior. We have obtained dynamic proton transmission images at two spatial magnifications and viewed both the radial and transverse axis of a solid cylindrical sample encased in aluminum. Images have been obtained with 3 to 15 μs temporal resolution and approximately 100 μm spatial resolution at the higher magnification. We observe case expansion from very early in the experiment, until case fragmentation. We observe spatially anisotropic features in the transmission which we attribute to cracking in the solid explosive, in agreement with previous measurements conducted on two dimensional samples with optical viewing. Digital analysis of the images also reveals spatially isotropic features which we attribute to the evolution of the loss of density by burning subsequent to thermal ignition.

The evolution of solid density within a thermal explosion II. Dynamic proton radiography of cracking and solid consumption by burning

Energy Technology Data Exchange (ETDEWEB)

Smilowitz, L.; Henson, B. F.; Romero, J. J.; Asay, B. W.; Saunders, A.; Merrill, F. E.; Morris, C. L.; Kwiatkowski, K.; Grim, G.; Mariam, F.; Schwartz, C. L.; Hogan, G.; Nedrow, P.; Murray, M. M.; Thompson, T. N.; Espinoza, C.; Lewis, D.; Bainbridge, J.; McNeil, W.; Rightley, P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); and others

2012-05-15

We report proton transmission images obtained subsequent to the laser assisted thermal ignition of a sample of PBX 9501 (a plastic bonded formulation of the explosive nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)). We describe the laser assisted thermal ignition technique as a means to synchronize a non-linear thermal ignition event while preserving the subsequent post-ignition behavior. We have obtained dynamic proton transmission images at two spatial magnifications and viewed both the radial and transverse axis of a solid cylindrical sample encased in aluminum. Images have been obtained with 3 to 15 {mu}s temporal resolution and approximately 100 {mu}m spatial resolution at the higher magnification. We observe case expansion from very early in the experiment, until case fragmentation. We observe spatially anisotropic features in the transmission which we attribute to cracking in the solid explosive, in agreement with previous measurements conducted on two dimensional samples with optical viewing. Digital analysis of the images also reveals spatially isotropic features which we attribute to the evolution of the loss of density by burning subsequent to thermal ignition.

Study of the thermal and suprathermal electron density fluctuations of the plasma in the Focus experiment

International Nuclear Information System (INIS)

Jolas, A.

1981-10-01

An experiment on Thomson scattering of ruby laser light by the electrons of a plasma produced by an intense discharge between the electrodes of a coaxial gun in a gas at low pressure has been carried out. It is shown that the imploding plasma is made up of layers with different characteristics: a dense plasma layer where the density fluctuations are isotropic and have a thermal level, and a tenuous plasma layer where the fluctuations are anisotropic, and strongly suprathermal. The suprathermal fluctuations are attributed to microscopic instabilities generated by the electric current circulating in the transition zone where the magnetic field penetrates the plasma [fr

Paramagnetic ionic liquids for measurements of density using magnetic levitation.

Science.gov (United States)

Bwambok, David K; Thuo, Martin M; Atkinson, Manza B J; Mirica, Katherine A; Shapiro, Nathan D; Whitesides, George M

2013-09-03

Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous or organic solutions: (i) negligible vapor pressures; (ii) low melting points; (iii) high thermal stabilities. In addition, the densities, magnetic susceptibilities, glass transition temperatures, thermal decomposition temperatures, viscosities, and hydrophobicities of PILs can be tuned over broad ranges by choosing the cation-anion pair. The low melting points and high thermal stabilities of PILs provide large liquidus windows for density measurements. This paper demonstrates applications and advantages of PILs in density-based analyses using MagLev.

Development of optimum process for electron beam cross-linking of high density polyethylene thermal energy storage pellets, process scale-up and production of application qualities of material

Science.gov (United States)

Salyer, I. O.

1980-01-01

The electron irradiation conditions required to prepare thermally from stable high density polyethylene (HDPE) were defined. The conditions were defined by evaluating the heat of fusion and the melting temperature of several HDPE specimens. The performance tests conducted on the specimens, including the thermal cycling tests in the thermal energy storage unit are described. The electron beam irradiation tests performed on the specimens, in which the total radiation dose received by the pellets, the electron beam current, the accelerating potential, and the atmospheres were varied, are discussed.

Growth of High-Density Zinc Oxide Nanorods on Porous Silicon by Thermal Evaporation

Directory of Open Access Journals (Sweden)

Nurul Izni Rusli

2012-12-01

Full Text Available The formation of high-density zinc oxide (ZnO nanorods on porous silicon (PS substrates at growth temperatures of 600–1000 °C by a simple thermal evaporation of zinc (Zn powder in the presence of oxygen (O2 gas was systematically investigated. The high-density growth of ZnO nanorods with (0002 orientation over a large area was attributed to the rough surface of PS, which provides appropriate planes to promote deposition of Zn or ZnOx seeds as nucleation sites for the subsequent growth of ZnO nanorods. The geometrical morphologies of ZnO nanorods are determined by the ZnOx seed structures, i.e., cluster or layer structures. The flower-like hexagonal-faceted ZnO nanorods grown at 600 °C seem to be generated from the sparsely distributed ZnOx nanoclusters. Vertically aligned hexagonal-faceted ZnO nanorods grown at 800 °C may be inferred from the formation of dense arrays of ZnOx clusters. The formation of disordered ZnO nanorods formed at 1000 °C may due to the formation of a ZnOx seed layer. The growth mechanism involved has been described by a combination of self-catalyzed vapor-liquid-solid (VLS and vapor-solid (VS mechanism. The results suggest that for a more precise study on the growth of ZnO nanostructures involving the introduction of seeds, the initial seed structures must be taken into account given their significant effects.

Dark-Matter Particles without Weak-Scale Masses or Weak Interactions

International Nuclear Information System (INIS)

Feng, Jonathan L.; Kumar, Jason

2008-01-01

We propose that dark matter is composed of particles that naturally have the correct thermal relic density, but have neither weak-scale masses nor weak interactions. These models emerge naturally from gauge-mediated supersymmetry breaking, where they elegantly solve the dark-matter problem. The framework accommodates single or multiple component dark matter, dark-matter masses from 10 MeV to 10 TeV, and interaction strengths from gravitational to strong. These candidates enhance many direct and indirect signals relative to weakly interacting massive particles and have qualitatively new implications for dark-matter searches and cosmological implications for colliders

Improvement of the thermal and thermo-oxidative stability of high-density polyethylene by free radical trapping of rare earth compound

Energy Technology Data Exchange (ETDEWEB)

Ran, Shiya; Zhao, Li; Han, Ligang [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China); Guo, Zhenghong, E-mail: guozhenghong@nit.zju.edu.cn [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); Fang, Zhengping [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China)

2015-07-20

Highlights: • Polyethylene filled with ytterbium trifluoromethanesulfonate was prepared. • A low Yb loading improved thermal stability of PE obviously by radical trapping. • Yb(OTf){sub 3} is expected to be an efficient thermal stabilizer for the polymer. - Abstract: A kind of rare earth compound, ytterbium trifluoromethanesulfonate (Yb(OTf){sub 3}), was introduced into high-density polyethylene (HDPE) by melt compounding to investigate the effect of Yb(OTf){sub 3} on the thermal and thermo-oxidative stability of HDPE. The results of thermogravimetric (TG) and differential scanning calorimetry (DSC) showed that the addition of Yb(OTf){sub 3} made the thermal degradation temperatures dramatically increased, the oxidative induction time (OIT) extended, and the enthalpy (ΔH{sub d}) reduced. Very low Yb(OTf){sub 3} loading (0.5 wt%) in HDPE could increase the onset degradation temperature in air from 334 to 407 °C, delay the OIT from 11.0 to 24.3 min, and decrease the ΔH{sub d} from 61.0 to 13.0 J/g remarkably. Electron spin resonance spectra (ESR), thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA-FTIR), rheological investigation and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that the free radicals-trapping ability of Yb(OTf){sub 3} was responsible for the improved thermal and thermo-oxidative stability.

arXiv The propagating speed of relic gravitational waves and their refractive index during inflation

CERN Document Server

Giovannini, Massimo

2018-06-02

If the refractive index of the tensor modes increases during a conventional inflationary stage of expansion the relic graviton spectrum is tilted towards high frequencies. Two apparently diverse parametrizations of this effect are shown to be related by a rescaling of the four-dimensional metric through a conformal factor that involves the refractive index itself. Non-monotonic spectra with a maximum in the MHz region correspond to a limited variation of the refractive index terminating well before the end of inflation. After exploring a general approach encompassing the ones proposed so far, we estimate the required sensitivity for the direct detection of the predicted gravitational radiation and demonstrate that the allowed regions of the parameter space are within reach for some of the planned detectors operating either in the audio band (like Ligo/Virgo and Kagra) or in the mHz band (like Lisa, Bbo and Decigo).

A Virtual Reconstruction Methodology for Archaeological Heritage in East Asia – Practical Experience from the Re-relic Program in China

Directory of Open Access Journals (Sweden)

Yan He

2013-11-01

Full Text Available There is as much abundance of archaeological heritage in East Asia as there is diversity in the methodology for its reconstruction and representation. The Re-relic program in China recognizes the uniqueness of archaeological heritage in East Asia and has developed a tailored virtual reconstruction methodology that is both scientifically robust and popular for public interpretation. The theoretical consideration and field experience over the years shall contribute to the global understanding of the value and technique in virtual reconstruction, while testifying to the very principles of Seville Charter.

Dark matter halos with cores from hierarchical structure formation

International Nuclear Information System (INIS)

Strigari, Louis E.; Kaplinghat, Manoj; Bullock, James S.

2007-01-01

We show that dark matter emerging from late decays (z or approx. 0.1 Mpc), and simultaneously generates observable constant-density cores in small dark matter halos. We refer to this class of models as meta-cold dark matter (mCDM), because it is born with nonrelativistic velocities from the decays of cold thermal relics. The constant-density cores are a result of the low phase-space density of mCDM at birth. Warm dark matter cannot produce similar size phase-space limited cores without saturating the Lyα power spectrum bounds. Dark matter-dominated galaxy rotation curves and stellar velocity dispersion profiles may provide the best means to discriminate between mCDM and CDM. mCDM candidates are motivated by the particle spectrum of supersymmetric and extra dimensional extensions to the standard model of particle physics

Thermal conductivity of an organic phase change material/expanded graphite composite across the phase change temperature range and a novel thermal conductivity model

International Nuclear Information System (INIS)

Ling, Ziye; Chen, Jiajie; Xu, Tao; Fang, Xiaoming; Gao, Xuenong; Zhang, Zhengguo

2015-01-01

Highlights: • Expanded graphite can improve thermal conductivity of RT44HC by 20–60 times. • Thermal conductivity of PCM/EG composites keeps constant before/after melting. • Thermal conductivity of PCMs nearly doubled during phase changing. • Thermal conductivity of composite PCM increases with density and percentage of EG. • The simple model predicts thermal conductivity of EG-based composites accurately. - Abstract: This work studies factors that affect the thermal conductivity of an organic phase change material (PCM), RT44HC/expanded graphite (EG) composite, which include: EG mass fraction, composite PCM density and temperature. The increase of EG mass fraction and bulk density will both enhance thermal conductivity of composite PCMs, by up to 60 times. Thermal conductivity of RT44HC/EG composites remains independent on temperature outside the phase change range (40–45 °C), but nearly doubles during the phase change. The narrow temperature change during the phase change allows the maximum heat flux or minimum temperature for heat source if attaching PCMs to a first (constant temperature) or second (constant heat flux) thermal boundary. At last, a simple thermal conductivity model for EG-based composites is put forward, based on only two parameters: mass fraction of EG and bulk density of the composite. This model is validated with experiment data presented in this paper and in literature, showing this model has general applicability to any composite of EG and poor thermal conductive materials

Thermal conductivity of technetium

International Nuclear Information System (INIS)

Minato, K.; Serizawa, H.; Fukuda, K.

1998-01-01

The thermal diffusivity of technetium was measured on a disk sample of 5 mm in diameter and 1 mm in thickness by the laser flash method from room temperature to 1173 K, and the thermal conductivity was determined by the measured thermal diffusivity and density, and the reported specific heat capacity. The thermal diffusivity of technetium decreases with increasing temperature though it is almost constant above 600 K. The thermal conductivity of technetium shows a minimum around 400 K, above which the thermal conductivity increases with temperature. The electronic and phonon components of the thermal conductivity were evaluated approximately. The increase in the thermal conductivity of technetium with temperature is due to the increase in the electronic component. (orig.)

Detection of non-thermal X-ray emission in the lobes and jets of Cygnus A

Science.gov (United States)

de Vries, M. N.; Wise, M. W.; Huppenkothen, D.; Nulsen, P. E. J.; Snios, B.; Hardcastle, M. J.; Birkinshaw, M.; Worrall, D. M.; Duffy, R. T.; McNamara, B. R.

2018-06-01

We present a spectral analysis of the lobes and X-ray jets of Cygnus A, using more than 2 Ms of Chandra observations. The X-ray jets are misaligned with the radio jets and significantly wider. We detect non-thermal emission components in both lobes and jets. For the eastern lobe and jet, we find 1 keV flux densities of 71_{-10}^{+10} nJy and 24_{-4}^{+4} nJy, and photon indices of 1.72_{-0.03}^{+0.03} and 1.64_{-0.04}^{+0.04} respectively. For the western lobe and jet, we find flux densities of 50_{-13}^{+12} nJy and 13_{-5}^{+5} nJy, and photon indices of 1.97_{-0.10}^{+0.23} and 1.86_{-0.12}^{+0.18} respectively. Using these results, we modeled the electron energy distributions of the lobes as broken power laws with age breaks. We find that a significant population of non-radiating particles is required to account for the total pressure of the eastern lobe. In the western lobe, no such population is required and the low energy cutoff to the electron distribution there needs to be raised to obtain pressures consistent with observations. This discrepancy is a consequence of the differing X-ray photon indices, which may indicate that the turnover in the inverse-Compton spectrum of the western lobe is at lower energies than in the eastern lobe. We modeled the emission from both jets as inverse-Compton emission. There is a narrow region of parameter space for which the X-ray jet can be a relic of an earlier active phase, although lack of knowledge about the jet's electron distribution and particle content makes the modelling uncertain.

Modeling of the thermal physical process and study on the reliability of linear energy density for selective laser melting

Directory of Open Access Journals (Sweden)

Zhaowei Xiang

2018-06-01

Full Text Available A finite element model considering volume shrinkage with powder-to-dense process of powder layer in selective laser melting (SLM is established. Comparison between models that consider and do not consider volume shrinkage or powder-to-dense process is carried out. Further, parametric analysis of laser power and scan speed is conducted and the reliability of linear energy density as a design parameter is investigated. The results show that the established model is an effective method and has better accuracy allowing for the temperature distribution, and the length and depth of molten pool. The maximum temperature is more sensitive to laser power than scan speed. The maximum heating rate and cooling rate increase with increasing scan speed at constant laser power and increase with increasing laser power at constant scan speed as well. The simulation results and experimental result reveal that linear energy density is not always reliable using as a design parameter in the SLM. Keywords: Selective laser melting, Volume shrinkage, Powder-to-dense process, Numerical modeling, Thermal analysis, Linear energy density

Density of liquid Ytterbium

International Nuclear Information System (INIS)

Stankus, S.V.; Basin, A.S.

1983-01-01

Results are presented for measurements of the density of metallic ytterbium in the liquid state and at the liquid-solid phase transition. Based on the numerical data obtained, the coefficient of thermal expansion βZ of the liquid and the density discontinuity on melting deltarho/sub m/ are calculated. The magnitudes of βZ and deltarho/sub m/ for the heavy lanthanides are compared

Supersymmetric model for dark matter and baryogenesis motivated by the recent CDMS result.

Science.gov (United States)

Allahverdi, Rouzbeh; Dutta, Bhaskar; Mohapatra, Rabindra N; Sinha, Kuver

2013-08-02

We discuss a supersymmetric model for cogenesis of dark and baryonic matter where the dark matter (DM) has mass in the 8-10 GeV range as indicated by several direct detection searches, including most recently the CDMS experiment with the desired cross section. The DM candidate is a real scalar field. Two key distinguishing features of the model are the following: (i) in contrast with the conventional weakly interacting massive particle dark matter scenarios where thermal freeze-out is responsible for the observed relic density, our model uses nonthermal production of dark matter after reheating of the Universe caused by moduli decay at temperatures below the QCD phase transition, a feature which alleviates the relic overabundance problem caused by small annihilation cross section of light DM particles and (ii) baryogenesis occurs also at similar low temperatures from the decay of TeV scale mediator particles arising from moduli decay. A possible test of this model is the existence of colored particles with TeV masses accessible at the LHC.

Phenomenology of ELDER dark matter

Science.gov (United States)

Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

2017-08-01

We explore the phenomenology of Elastically Decoupling Relic (ELDER) dark matter. ELDER is a thermal relic whose present density is determined primarily by the cross-section of its elastic scattering off Standard Model (SM) particles. Assuming that this scattering is mediated by a kinetically mixed dark photon, we argue that the ELDER scenario makes robust predictions for electron-recoil direct-detection experiments, as well as for dark photon searches. These predictions are independent of the details of interactions within the dark sector. Together with the closely related Strongly-Interacting Massive Particle (SIMP) scenario, the ELDER predictions provide a physically motivated, well-defined target region, which will be almost entirely accessible to the next generation of searches for sub-GeV dark matter and dark photons. We provide useful analytic approximations for various quantities of interest in the ELDER scenario, and discuss two simple renormalizable toy models which incorporate the required strong number-changing interactions among the ELDERs, as well as explicitly implement the coupling to electrons via the dark photon portal.

Neutrinophilic two Higgs doublet model with dark matter under an alternative U(1)_{B-L} gauge symmetry

Science.gov (United States)

Nomura, Takaaki; Okada, Hiroshi

2018-03-01

We propose a Dirac type active neutrino with rank two mass matrix and a Majorana fermion dark matter candidate with an alternative local U(1)_{B-L} extension of neutrinophilic two Higgs doublet model. Our dark matter candidate can be stabilized due to charge assignment under the gauge symmetry without imposing extra discrete Z_2 symmetry and the relic density is obtained from an Z' boson exchanging process. Taking into account collider constraints on the Z' boson mass and coupling, we estimate the relic density.

Thermal Transport in High-Strength Polymethacrylimide (PMI) Foam Insulations

Science.gov (United States)

Qiu, L.; Zheng, X. H.; Zhu, J.; Tang, D. W.; Yang, S. Y.; Hu, A. J.; Wang, L. L.; Li, S. S.

2015-11-01

Thermal transport in high-strength polymethacrylimide (PMI) foam insulations is described, with special emphasis on the density and temperature effects on the thermal transport performance. Measurements of the effective thermal conductivity are performed by a freestanding sensor-based 3ω method. A linear relationship between the density and the effective thermal conductivity is observed. Based on the analysis of the foam insulation morphological structures and the corresponding geometrical cell model, the quantitative contribution of the solid conductivity and the gas conductivity as well as the radiative conductivity to the total effective thermal conductivity as a function of the density and temperature is calculated. The agreement between the curves of the results from the developed model and experimental data indicate the model can be used for PMI foam insulating performance optimization.

Thermal and active fluctuations of a compressible bilayer vesicle

Science.gov (United States)

Sachin Krishnan, T. V.; Yasuda, Kento; Okamoto, Ryuichi; Komura, Shigeyuki

2018-05-01

We discuss thermal and active fluctuations of a compressible bilayer vesicle by using the results of hydrodynamic theory for vesicles. Coupled Langevin equations for the membrane deformation and the density fields are employed to calculate the power spectral density matrix of membrane fluctuations. Thermal contribution is obtained by means of the fluctuation dissipation theorem, whereas active contribution is calculated from exponentially decaying time correlation functions of active random forces. We obtain the total power spectral density as a sum of thermal and active contributions. An apparent response function is further calculated in order to compare with the recent microrheology experiment on red blood cells. An enhanced response is predicted in the low-frequency regime for non-thermal active fluctuations.

The local contribution to the microwave background radiation

International Nuclear Information System (INIS)

Pecker, Jean-Claude; Narlikar, Jayant V.; Ochsenbein, Francois; Wickramasinghe, Chandra

2015-01-01

The observed microwave background radiation (MBR) is commonly interpreted as the relic of an early hot universe, and its observed features (spectrum and anisotropy) are explained in terms of properties of the early universe. Here we describe a complementary, even possibly alternative, interpretation of MBR, first proposed in the early 20 th century, and adapt it to modern observations. For example, the stellar Hipparcos data show that the energy density of starlight from the Milky Way, if suitably thermalized, yields a temperature of ∼2.81 K. This and other arguments given here strongly suggest that the origin of MBR may lie, at least in a very large part, in re-radiation of thermalized galactic starlight. The strengths and weaknesses of this alternative radical explanation are discussed. (paper)

Structural relaxation and thermal conductivity of high-pressure formed, high-density di-n-butyl phthalate glass and pressure induced departures from equilibrium state.

Science.gov (United States)

Johari, G P; Andersson, Ove

2017-06-21

We report a study of structural relaxation of high-density glasses of di-n-butyl phthalate (DBP) by measuring thermal conductivity, κ, under conditions of pressure and temperature (p,T) designed to modify both the vibrational and configurational states of a glass. Various high-density glassy states of DBP were formed by (i) cooling the liquid under a fixed high p and partially depressurizing the glass, (ii) isothermal annealing of the depressurized glass, and (iii) pressurizing the glass formed by cooling the liquid under low p. At a given low p, κ of the glass formed by cooling under high p is higher than that of the glass formed by cooling under low p, and the difference increases as glass formation p is increased. κ of the glass formed under 1 GPa is ∼20% higher at ambient p than κ of the glass formed at ambient p. On heating at low p, κ decreases until the glass to liquid transition range is reached. This is the opposite of the increase in κ observed when a glass formed under a certain p is heated under the same p. At a given high p, κ of the low-density glass formed by cooling at low p is lower than that of the high-density glass formed by cooling at that high p. On heating at high p, κ increases until the glass to liquid transition range is reached. The effects observed are due to a thermally assisted approach toward equilibrium at p different from the glass formation p. In all cases, the density, enthalpy, and entropy would change until the glasses become metastable liquids at a fixed p, thus qualitatively relating κ to variation in these properties.

Influence of moisture content and temperature on thermal conductivity and thermal diffusivity of rice flours

Science.gov (United States)

The thermal conductivity and thermal diffusivity of four types of rice flours and one type of rice protein were determine at temperatures ranging from 4.8 to 36.8 C, bulk densities 535 to 875.8 kg/m3, and moisture contents 2.6 to 16.7 percent (w.b.), using a KD2 Thermal Properties Analyzer. It was ...

Characterization of radiation-cross-linked, high-density polyethylene for thermal energy storage

International Nuclear Information System (INIS)

Whitaker, R.B.; Craven, S.M.; Etter, D.E.; Jendrek, E.F.; Nease, A.B.

1983-01-01

Electron beam cross-linked high-density polyethylene (HDPE) pellets (DuPont Alathon, 0.93 MI) have been characterized for potential utility in thermal energy storage applications, before and after up to 500 melt-freeze cycles in ethylene glycol. Up to 95% of the HDPE's initial DSC differential scanning calorimetry Δ H/sub f/ value (44.7 cal/g) (at 1.25 0 C/min cooling rates) was retained up to 9.0 Mrad radiation dosage. Form-stability after 500 melt-freeze cycles was very good at this dosage level. X-ray diffraction measurements showed little difference between irradiated HDPE's and the unirradiated control, indicating that cross-linking occurred primarily in the amorphous regions. FTIR spectroscopy showed the pellets to be uniformly reacted. The ratios of the 965-cm -1 absorption band (trans RCH=CRH') to the 909-cm -1 band (RCH=CH 2 ) increased with increasing radiation dosage, up to 18 Mrad. Gel contents reached a maximum of 75% at the 13.5 Mrad dosage, indicating that other reactions, in addition to cross-linking, occurred at the highest (18 Mrad) dosage level. 15 references, 5 figures, 4 tables

SOME MOISTURE DEPENDENT THERMAL PROPERTIES AND ...

African Journals Online (AJOL)

The thermal heat conductivity, specific heat capacity, thermal heat diffusivity and bulk density of Prosopis africana seeds were determined as a function of moisture content. Specific heat capacity was measured by the method of mixture while the thermal heat conductivity was measured by the guarded hot plate method.

High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

Directory of Open Access Journals (Sweden)

Birm-June Kim

2013-09-01

Full Text Available The effect of individual and combined talc and glass fibers (GFs on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance.

Science.gov (United States)

Huang, Runzhou; Xu, Xinwu; Lee, Sunyoung; Zhang, Yang; Kim, Birm-June; Wu, Qinglin

2013-09-17

The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

Thermal characterizations of the paraffin wax/low density polyethylene blends as a solid fuel

Energy Technology Data Exchange (ETDEWEB)

Kim, Soojong; Moon, Heejang; Kim, Jinkon, E-mail: jkkim@kau.ac.kr

2015-08-10

Highlights: • Regression rate of blends fuel is higher than polymer fuel. • LDPE is an effective mixing ingredient for the combustion efficiency. • Blends fuel is a uniform mixture with two degradation steps. • LDPE plays a positive role for the low sensitivity to the thermal deformation • Blends with low LDPE content can be an effective fuel for hybrid rocket application. - Abstract: Thermal characterizations of a novel solid fuel for hybrid rocket application, based on the paraffin wax blends with low density polyethylene (LDPE) concentration of 5% (SF-5) and 10% (SF-10) were conducted. Both the increased regression rate in comparison with the polymeric fuel, and the improved combustion efficiency in comparison with the pure paraffin fuel reveal that the blend fuels achieve higher combustion performance. The morphology of the shape stabilized paraffin wax/LDPE blends was characterized by the scanning electron microscopy (SEM). Although the SEM observation indicated the blends have uniform mixtures, they showed two degradation steps confirming the immiscibility of components in the crystalline phase from thermogravimetric analysis (TGA). The differential scanning calorimeter (DSC) results showed that the melting temperature of LDPE in the blends decreased with an increase of paraffin wax content. The decreasing total specific melting enthalpy of blended fuels with decreasing paraffin wax content is in fairly good agreement with the additive rule. In thermomechanical analysis (TMA), the linear coefficient of thermal expansion (LCTE) seems to decrease with an increase of LDPE loading, however, the loaded LDPE do merely affect the LCTE in case of the blends with low LDPE concentration. It was found that a blend of low concentration of LDPE with a relatively high concentration of paraffin wax can lead to a potential novel fuel for rocket application, a contrary case with respect to the field of phase change materials (PCM) where a blend of high concentration

Thermal characterizations of the paraffin wax/low density polyethylene blends as a solid fuel

International Nuclear Information System (INIS)

Kim, Soojong; Moon, Heejang; Kim, Jinkon

2015-01-01

Highlights: • Regression rate of blends fuel is higher than polymer fuel. • LDPE is an effective mixing ingredient for the combustion efficiency. • Blends fuel is a uniform mixture with two degradation steps. • LDPE plays a positive role for the low sensitivity to the thermal deformation • Blends with low LDPE content can be an effective fuel for hybrid rocket application. - Abstract: Thermal characterizations of a novel solid fuel for hybrid rocket application, based on the paraffin wax blends with low density polyethylene (LDPE) concentration of 5% (SF-5) and 10% (SF-10) were conducted. Both the increased regression rate in comparison with the polymeric fuel, and the improved combustion efficiency in comparison with the pure paraffin fuel reveal that the blend fuels achieve higher combustion performance. The morphology of the shape stabilized paraffin wax/LDPE blends was characterized by the scanning electron microscopy (SEM). Although the SEM observation indicated the blends have uniform mixtures, they showed two degradation steps confirming the immiscibility of components in the crystalline phase from thermogravimetric analysis (TGA). The differential scanning calorimeter (DSC) results showed that the melting temperature of LDPE in the blends decreased with an increase of paraffin wax content. The decreasing total specific melting enthalpy of blended fuels with decreasing paraffin wax content is in fairly good agreement with the additive rule. In thermomechanical analysis (TMA), the linear coefficient of thermal expansion (LCTE) seems to decrease with an increase of LDPE loading, however, the loaded LDPE do merely affect the LCTE in case of the blends with low LDPE concentration. It was found that a blend of low concentration of LDPE with a relatively high concentration of paraffin wax can lead to a potential novel fuel for rocket application, a contrary case with respect to the field of phase change materials (PCM) where a blend of high concentration

Prediction of the Thermal Conductivity of Refrigerants by Computational Methods and Artificial Neural Network.

Science.gov (United States)

Ghaderi, Forouzan; Ghaderi, Amir H; Ghaderi, Noushin; Najafi, Bijan

2017-01-01

Background: The thermal conductivity of fluids can be calculated by several computational methods. However, these methods are reliable only at the confined levels of density, and there is no specific computational method for calculating thermal conductivity in the wide ranges of density. Methods: In this paper, two methods, an Artificial Neural Network (ANN) approach and a computational method established upon the Rainwater-Friend theory, were used to predict the value of thermal conductivity in all ranges of density. The thermal conductivity of six refrigerants, R12, R14, R32, R115, R143, and R152 was predicted by these methods and the effectiveness of models was specified and compared. Results: The results show that the computational method is a usable method for predicting thermal conductivity at low levels of density. However, the efficiency of this model is considerably reduced in the mid-range of density. It means that this model cannot be used at density levels which are higher than 6. On the other hand, the ANN approach is a reliable method for thermal conductivity prediction in all ranges of density. The best accuracy of ANN is achieved when the number of units is increased in the hidden layer. Conclusion: The results of the computational method indicate that the regular dependence between thermal conductivity and density at higher densities is eliminated. It can develop a nonlinear problem. Therefore, analytical approaches are not able to predict thermal conductivity in wide ranges of density. Instead, a nonlinear approach such as, ANN is a valuable method for this purpose.

Metal hydride-based thermal energy storage systems

Science.gov (United States)

Vajo, John J.; Fang, Zhigang

2017-10-03

The invention provides a thermal energy storage system comprising a metal-containing first material with a thermal energy storage density of about 1300 kJ/kg to about 2200 kJ/kg based on hydrogenation; a metal-containing second material with a thermal energy storage density of about 200 kJ/kg to about 1000 kJ/kg based on hydrogenation; and a hydrogen conduit for reversibly transporting hydrogen between the first material and the second material. At a temperature of 20.degree. C. and in 1 hour, at least 90% of the metal is converted to the hydride. At a temperature of 0.degree. C. and in 1 hour, at least 90% of the metal hydride is converted to the metal and hydrogen. The disclosed metal hydride materials have a combination of thermodynamic energy storage densities and kinetic power capabilities that previously have not been demonstrated. This performance enables practical use of thermal energy storage systems for electric vehicle heating and cooling.

Density limit studies in the large helical device

International Nuclear Information System (INIS)

Peterson, B.J.; Miyazawa, J.; Nishimura, K.

2005-01-01

Steady state densities of up to 1.6 x 10 20 m -3 have been sustained using gas puff fuelling and NBI heating up to 11 MW in the Large Helical Device (LHD). The density limit in LHD is observed to be ∼ 1.6 times the Sudo limit. The density is ultimately limited by radiative collapse which is attributed to the onset of a radiative thermal instability of the light impurities in the edge region of the plasma based on several observations. First of all the onset of the radiative thermal instability is tied to a certain edge temperature threshold. Secondly, the onset of thermal instability occurs first in oxygen and then carbon as expected from their cooling rate temperature dependencies. Finally, radiation profiles show that as the temperature drops and the plasma collapses the radiating zone broadens and moves inward. In addition, comparison with the total radiated power behaviour indicates that Carbon is the dominant radiator. Two dimensional tomographic inversions of AXUVD array data and comparison of modelling with images of radiation brightness from imaging bolometers and indicate that the poloidal asymmetry which accompanies the radiative collapse is toroidally symmetric. Ain addition to the operational density limit where the discharge is terminated by radiative collapse, a confinement limit has been recognized in LHD. This confinement limit appears at lower density than the operational density limit, similar to the saturated ohmic confinement observed in tokamaks. To investigate the physics behind this degradation, the parameter dependence of the thermal diffusivity, χ, has been investigated. While the temperature dependence in ISS95 is as strong as the gyro-Bohm model of χ ∝ T e 1.5 , weaker T e dependence of χ ∝ T e 0.5 appears in the high-density regime. Such weak T e dependence results in the weak density dependence of the global energy confinement as τ E ∝ n e 13 -bar. (author)

Stabilization of the Rayleigh-Taylor instability by convection and thermal conduction in smooth density gradient: WKB analysis

International Nuclear Information System (INIS)

Bud'ko, A.B.; Liberman, M.A.; Bondarenko, E.A.

1992-01-01

Since development of the RT modes in the ablatively accelerated plasma of laser targets imposes crucial limitations on symmetry of spherical implosions and hence on energy cumulation, it has been the subject of intensive numerical and analytical analysis in the recent years, particularly in the context of inertial confinement fusion. Recent thin-foil ablative-acceleration experiments as well as the results of 2D numerical simulations demonstrated substantial reduction of the instability growth rates compared with the classical theory predictions up to the total stabilization in the short-wavelength limit. The numerical results indicated that the main stabilization mechanism is convection. To derive the scaling laws for the RT growth rates and cut-off wavenumbers in the wide range of flow parameters, analytical solutions attract special interest. The analytical approach based on the discontinuity model was developed to analyze the reduction of the RT growth rates by the plasma convective flow and the thermal conductivity effects. The following major problem arises in the discontinuity approximation, which leaves the solution undetermined: the number of the boundary conditions on the perturbed ablation surface is not sufficient to derive the dispersion equation. One needs additional boundary conditions not associated with the conservation laws on the discontinuity surface to close the system of linearized equations for small perturbations. The stabilization effect of highly structured hydrodynamic profiles was studied by Mikaelian and Munro for a stationary plasma. Nevertheless, no reasonable analytical model was constructed taking into account the combined convective, thermal conductivity and density gradient reduction of the RT growth rates. In this report we develop the analytical approach based on the WKB approximation to analyze the stabilization of the RT modes in plasma with smooth density and velocity gradients. (author) 9 refs., 1 fig

Effect of ionizing radiation on mechanical and thermal properties of low-density polyethylene containing pro-degradant agents

International Nuclear Information System (INIS)

Bardi, Marcelo A.G.; Kodama, Yasko; Machado, Luci D.B.; Giovedi, Claudia; Rosa, Derval S.

2009-01-01

The wide use of plastics on packages of short-lifetime products has presented harmful consequences for the environment due to their low degradation rate. By this way, improved results to the bio-assimilation of polyolefins have been achieved by the incorporation of pro-oxidant components. The aim of this work is to evaluate the mechanical and thermal behavior of low-density polyethylene (LDPE) modified by those agents and submitted to ionizing radiation by gamma rays. LDPE was modified using a masterbatch containing calcium stearate (CaSt), or magnesium stearate (MgSt) or Clariant R commercial metallic complex. The final amount of stearate in modified LDPE was 0.2%. The films were obtained by compression molding. Samples were gamma irradiated at absorbed doses of 15 kGy and 100 kGy. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were performed on samples, as well as mechanical analysis by universal testing machine. Thermal properties of samples presenting pro-degradant agents were affected by the ionizing radiation in the dose range studied, and some of the mechanical properties were clearly modified by reducing their values of tensile strength at break and elongation at break. (author)

Effect of ionizing radiation on mechanical and thermal properties of low-density polyethylene containing pro-degradant agents

Energy Technology Data Exchange (ETDEWEB)

Bardi, Marcelo A.G.; Kodama, Yasko; Machado, Luci D.B., E-mail: magbardi@ipen.b, E-mail: ykodama@ipen.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Giovedi, Claudia, E-mail: giovedi@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Rosa, Derval S., E-mail: derval.rosa@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

2009-07-01

The wide use of plastics on packages of short-lifetime products has presented harmful consequences for the environment due to their low degradation rate. By this way, improved results to the bio-assimilation of polyolefins have been achieved by the incorporation of pro-oxidant components. The aim of this work is to evaluate the mechanical and thermal behavior of low-density polyethylene (LDPE) modified by those agents and submitted to ionizing radiation by gamma rays. LDPE was modified using a masterbatch containing calcium stearate (CaSt), or magnesium stearate (MgSt) or Clariant{sup R} commercial metallic complex. The final amount of stearate in modified LDPE was 0.2%. The films were obtained by compression molding. Samples were gamma irradiated at absorbed doses of 15 kGy and 100 kGy. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were performed on samples, as well as mechanical analysis by universal testing machine. Thermal properties of samples presenting pro-degradant agents were affected by the ionizing radiation in the dose range studied, and some of the mechanical properties were clearly modified by reducing their values of tensile strength at break and elongation at break. (author)

Density of liquid Hg(1-x)Cd(x)Te

Science.gov (United States)

Chandra, D.; Holland, L. R.

1983-01-01

Negative thermal expansion has been established in liquid Hg(1-x)Cd(x)Te for x less than 0.2 employing a pycnometric method. Pure HgTe increases in density from its melting point at 670 C to a maximum value at 750 C, where normal thermal expansion progressively resumes. The dependence of density on temperature for liquid Hg(1-x)Cd(x)Te arises almost exclusively from the HgTe portion of the melt, while CdTe acts as a diluent. The temperature corresponding to the maximum density changes slightly with composition, increasing by about 5 C for x = 0.1.

Dark Matter from new Technicolor Theories

DEFF Research Database (Denmark)

Bjarke Gudnason, Sven; Kouvaris, Christoforos; Sannino, Francesco

2006-01-01

We investigate dark matter candidates emerging in recently proposed technicolor theories. We determine the relic density of the lightest, neutral, stable technibaryon having imposed weak thermal equilibrium conditions and overall electric neutrality of the Universe. In addition we consider...... sphaleron processes that violate baryon, lepton and technibaryon number. Our analysis is performed in the case of a first order electroweak phase transition as well as a second order one. We argue that, in both cases, the new technibaryon contributes to the dark matter in the Universe. Finally we examine...... the problem of the constraints on these types of dark matter components from earth based experiments....

Thermal shock investigation of silicon nitride

International Nuclear Information System (INIS)

Ziegler, G.; Leucht, R.

1977-01-01

In this work, the thermal shock properties of commercial reaction-bonded Si 3 N 4 quality material (RBSN), of commercial hot-pressed Si 3 N 4 (HPSN) and of different laboratory grades of hot-pressed Si 3 N 4 were examined. The thermal shock properties of RBSN quality material differ according to the structure considerably: The critical temperature difference for sample crossections of 5 x 5 or 6 x 6 mm after quenching in oil lies between 730 0 C and over 1400 0 C. The best thermal shock properties are shown by high density RBSN quality material having very fine pores and high initial strength. The results indicate that for RBSN large pores and density inhomogenities are responsible for bad thermal shock properties. Resistance to fast temperature change is higher for hot-pressed Si 3 N 4 than for RBSN quality material. In HPSN, the thermal shock results show dependence on structure. High MgO content and the associated coarse rod-shaped configuration of the β phase and structural inhomogenities affect the thermal shock properties in an adverse way. (orig.) [de

Thermal conductivity of graphene with defects induced by electron beam irradiation

Science.gov (United States)

Malekpour, Hoda; Ramnani, Pankaj; Srinivasan, Srilok; Balasubramanian, Ganesh; Nika, Denis L.; Mulchandani, Ashok; Lake, Roger K.; Balandin, Alexander A.

2016-07-01

We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ~7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 1010 cm-2 to 1.8 × 1011 cm-2 the thermal conductivity decreases from ~(1.8 +/- 0.2) × 103 W mK-1 to ~(4.0 +/- 0.2) × 102 W mK-1 near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ~400 W mK-1. The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ~7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 1010 cm-2 to 1.8 × 1011 cm-2 the thermal conductivity decreases from ~(1.8 +/- 0.2) × 103 W mK-1 to ~(4.0 +/- 0.2) × 102 W mK-1 near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ~400 W mK-1. The thermal conductivity dependence on the defect density is

Thermal properties of self-gravitating plane-symmetric configuration

Energy Technology Data Exchange (ETDEWEB)

Hara, T; Ikeuchi, S [Kyoto Univ. (Japan). Dept. of Physics; Sugimoto, D

1976-09-01

As a limiting case of rotating stars, thermal properties of infinite plane-symmetric self-gravitating gas are investigated. Such a configuration is characterized by surface density of the plane instead of stellar mass. In the Kelvin contraction, temperature of the interior decreases, if the surface density is kept constant. If the accretion of matter takes place, or if the angular momenta are transferred outward, the surface density will increase. In this case, the temperature of the interior may increase. When a nuclear burning is ignited, it is thermally unstable in most cases, even when electrons are non-degenerate. This thermal instability is one of the essential differences of the plane-symmetric configuration from the spherical star. Such instabilities are computed for different cases of nuclear fuels. This type of nuclear instability is the same phenomenon as thermal instability of a thin shell burning in a spherical star.

Are Brands Postmodern Relics? Taking a Closer Look at New Sacred Objects

Directory of Open Access Journals (Sweden)

Stéphane DUFOUR

2011-01-01

Full Text Available Ever since the Church lost its monopoly on the sacred, no longer able to solely determine its form or contents, the social sphere has gradually taken over this value, applying it to new human and social objects. As a result, the modes of expression of the sacred have multiplied, along with the subjective and intimate experiences of modern individualism. Among the vast number of potential manifestations of this value, to which almost everything now seems to aspire, this paper will concentrate on commercial brands as vectors of meaning, with the hypothesis that some of them seek to position themselves, in postmodern society, as new figures of the sacred. This area of study is close to that of the sociologist Adam Arvidsson, when he describes brands as religious objects. If brands are less interested in selling products than in creating an affective experience, Arvidsson assimilates them to modern relics. However, this paper goes beyond metaphors, to examine the rhetorical strategies (discourse, rituals, representations, imagery through which brands construct meaning around sacred objects. Situated between a branch of marketing which concentrates on sacralising commercial products, and a theory popular in the English-speaking world, which has illustrated how the media work to sacralise products and brands, this paper uses a communicational approach to analyse the construction of meaning, by brands looking to make themselves (appear sacred.

On the v-representability of ensemble densities of electron systems

Science.gov (United States)

Gonis, A.; Däne, M.

2018-05-01

Analogously to the case at zero temperature, where the density of the ground state of an interacting many-particle system determines uniquely (within an arbitrary additive constant) the external potential acting on the system, the thermal average of the density over an ensemble defined by the Boltzmann distribution at the minimum of the thermodynamic potential, or the free energy, determines the external potential uniquely (and not just modulo a constant) acting on a system described by this thermodynamic potential or free energy. The paper describes a formal procedure that generates the domain of a constrained search over general ensembles (at zero or elevated temperatures) that lead to a given density, including as a special case a density thermally averaged at a given temperature, and in the case of a v-representable density determines the external potential leading to the ensemble density. As an immediate consequence of the general formalism, the concept of v-representability is extended beyond the hitherto discussed case of ground state densities to encompass excited states as well. Specific application to thermally averaged densities solves the v-representability problem in connection with the Mermin functional in a manner analogous to that in which this problem was recently settled with respect to the Hohenberg and Kohn functional. The main formalism is illustrated with numerical results for ensembles of one-dimensional, non-interacting systems of particles under a harmonic potential.

The effect of the ergodic divertor on electron thermal confinement

International Nuclear Information System (INIS)

Harris, G.R.; Capes, H.; Garbet, X.

1992-06-01

The thermal confinement within the confinement zone of Tore Supra ohmically heated deuterium plasmas bounded by the ergodic divertor (ED) configuration is studied in a 1 1/2D analysis of the local power balance. Although the edge electron temperature and mean electron density (n e ) are both on average halved with application of the ED, the mean electron thermal diffusivity χ e shows the same density dependence as exhibited by standard ohmic limiter discharges, i.e., an Alcator-like inverse dependence on (n e ) at low density and a saturation at high density. The ion thermal transport at low to medium densities in both limiter and ED discharges is between 10 to 20 times that predicted by neoclassical theory. Comparing ED and limiter plasmas of the same density, a strong plasma decontamination is observed, with a reduction, in Z eff by between 1.0 to 1.5. The effective decoupling of (n e ) and Z eff by the ED and the invariant behaviour of χ e imply that electron thermal transport is only weakly dependent on Z eff in ohmic Tore Supra discharges

Graphene Thermal Properties: Applications in Thermal Management and Energy Storage

Directory of Open Access Journals (Sweden)

Jackie D. Renteria

2014-11-01

Full Text Available We review the thermal properties of graphene, few-layer graphene and graphene nanoribbons, and discuss practical applications of graphene in thermal management and energy storage. The first part of the review describes the state-of-the-art in the graphene thermal field focusing on recently reported experimental and theoretical data for heat conduction in graphene and graphene nanoribbons. The effects of the sample size, shape, quality, strain distribution, isotope composition, and point-defect concentration are included in the summary. The second part of the review outlines thermal properties of graphene-enhanced phase change materials used in energy storage. It is shown that the use of liquid-phase-exfoliated graphene as filler material in phase change materials is promising for thermal management of high-power-density battery parks. The reported experimental and modeling results indicate that graphene has the potential to outperform metal nanoparticles, carbon nanotubes, and other carbon allotropes as filler in thermal management materials.

Thermal carrying capacity for a thermally-sensitive species at the warmest edge of its range.

Directory of Open Access Journals (Sweden)

Daniel Ayllón

Full Text Available Anthropogenic environmental change is causing unprecedented rates of population extirpation and altering the setting of range limits for many species. Significant population declines may occur however before any reduction in range is observed. Determining and modelling the factors driving population size and trends is consequently critical to predict trajectories of change and future extinction risk. We tracked during 12 years 51 populations of a cold-water fish species (brown trout Salmo trutta living along a temperature gradient at the warmest thermal edge of its range. We developed a carrying capacity model in which maximum population size is limited by physical habitat conditions and regulated through territoriality. We first tested whether population numbers were driven by carrying capacity dynamics and then targeted on establishing (1 the temperature thresholds beyond which population numbers switch from being physical habitat- to temperature-limited; and (2 the rate at which carrying capacity declines with temperature within limiting thermal ranges. Carrying capacity along with emergent density-dependent responses explained up to 76% of spatio-temporal density variability of juveniles and adults but only 50% of young-of-the-year's. By contrast, young-of-the-year trout were highly sensitive to thermal conditions, their performance declining with temperature at a higher rate than older life stages, and disruptions being triggered at lower temperature thresholds. Results suggest that limiting temperature effects were progressively stronger with increasing anthropogenic disturbance. There was however a critical threshold, matching the incipient thermal limit for survival, beyond which realized density was always below potential numbers irrespective of disturbance intensity. We additionally found a lower threshold, matching the thermal limit for feeding, beyond which even unaltered populations declined. We predict that most of our study

Thermal electron mobilities in low density gaseous mixtures

International Nuclear Information System (INIS)

Dmitriev, O.W.; Tchorzewska, W.; Szamrej, I.; Forys, M.

1992-01-01

A new method of obtaining thermal electron mobilities from experimental dependencies observed in the electron swarm is described; the method is suitable for both electron accepting and non-accepting systems. The electron mobilities for CO 2 , CH 4 C 2 H 6 as well as for N 2 , Ar, Xe, Kr and their mixtures with carbon dioxide are obtained. (Author)

Thermal Radiation Effects on Thermal Explosion in Polydisperse Fuel Spray-Probabilistic Model

Directory of Open Access Journals (Sweden)

Ophir Navea

2011-06-01

Full Text Available We investigate the effect of thermal radiation on the dynamics of a thermal explosion of polydisperse fuel spray with a complete description of the chemistry via a single-step two-reactant model of general order. The polydisperse spray is modeled using a Probability Density Function (PDF. The thermal radiation energy exchange between the evaporation surface of the fuel droplets and the burning gas is described using the Marshak boundary conditions. An explicit expression of the critical condition for thermal explosion limit is derived analytically and represents a generalization of the critical parameter of the classical Semenov theory. Because we investigated the model in the range where the temperature is very high, the effect of the thermal radiation is significant.

The Positronium Radiative Combination Spectrum: Calculation in the Limit of Thermal Positrons and Low Densities

Science.gov (United States)

Wallyn, P.; Mahoney, W. A.; Durouchoux, Ph.; Chapuis, C.

1996-01-01

We calculate the intensities of the positronium de-excitation lines for two processes: (1) the radiative combination of free thermal electrons and positrons for transitions with principal quantum number n less than 20, and (2) charge exchange between free positrons and hydrogen and helium atoms, restricting our evaluation to the Lyman-alpha line. We consider a low-density medium modeled by the case A assumption of Baker & Menzel and use the "nL method" of Pengelly to calculate the absolute intensities. We also evaluate the positronium fine and hyperfine intensities and show that these transitions are in all cases much weaker than positronium de-excitation lines in the same wavelength range. We also extrapolate our positronium de-excitation intensities to the submillimeter, millimeter, and centimeter wavelengths. Our results favor the search of infrared transitions of positronium lines for point sources when the visual extinction A, is greater than approx. 5.

Microwave background anisotropy and decaying-particle models for a flat universe

International Nuclear Information System (INIS)

Vittorio, N.; Silk, J.

1985-01-01

The fine-scale anisotropy of the cosmic microwave background radiation, induced by primordial scale-invariant adiabatic density fluctuations, has been studied in flat cosmological models dominated by relativistic particles from the recent decay of a massive relic-particle species. We find that, if the relic-particle species consists of massive, unstable neutrinos, there is appreciable, and probably excessive, fine-scale anisotropy in the cosmic microwave background

Dark matter asymmetry in supersymmetric Dirac leptogenesis

International Nuclear Information System (INIS)

Choi, Ki-Young; Chun, Eung Jin; Shin, Chang Sub

2013-01-01

We discuss asymmetric or symmetric dark matter candidate in the supersymmetric Dirac leptogenesis scenario. By introducing a singlet superfield coupling to right-handed neutrinos, the overabundance problem of dark matter can be evaded and various possibilities for dark matter candidate arise. If the singlino is the lightest supersymmetric particle (LSP), it becomes naturally asymmetric dark matter. On the other hand, the right-handed sneutrino is a symmetric dark matter candidate whose relic density can be determined by the usual thermal freeze-out process. The conventional neutralino or gravitino LSP can be also a dark matter candidate as its non-thermal production from the right-handed sneutrino can be controlled appropriately. In our scenario, the late-decay of heavy supersymmetric particles mainly produces the right-handed sneutrino and neutrino which is harmless to the standard prediction of the Big-Bang Nucleosynthesis

Geothermal properties of Swiss Molasse Basin (depth range 0-500 m) - 2006 upgrade of the thermal conductivity, heat capacity, rock density and porosity data base

International Nuclear Information System (INIS)

Leu, W.; Megel, T.; Schaerli, U.

2006-01-01

The main aim of this project is the preparation of a specific data base of geothermal properties for typical rocks of the Swiss Molasse Basin (depth interval 0-500 m). The project includes the development of a new laboratory tool for efficient heat capacity measurements on rock samples, numerous new measurements of geothermal rock properties in the laboratory and calculation of such data from geophysical borehole logs. In the geographical area under review, 282 rock samples, mainly from deep boreholes, were analyzed with the successfully calibrated new heat capacity device and conventional thermal conductivity measuring techniques (cuttings and cores). Based on sonic and density log data from exploration wells, 374 additional data points were generated. This new data base characterizes in detail the six main lithological rock types in the three Molasse groups OSM, OMM and USM within the Swiss Plateau Molasse. The statistical evaluation of all data illustrates the regional variation of the petrophysical and geothermal parameters. For most data groups bulk rock density and thermal conductivity increase, whereas heat capacity decreases in the direction towards the Alpine front. Thermal conductivity shows a distinct increase with depth. Based on this new information and with the aid of the evaluation software tool SwEWS, the costs of planned geothermal installations can be optimized thanks to more precise heat extraction simulations with existing software packages like COSOND, TRNSYS, EWS or WPcalc. (author)

Thermal shock test of TiC and graphite

International Nuclear Information System (INIS)

Shirakawa, H.; Okamura, J.; Son, P.; Miyake, M.

1989-01-01

Thermal shock tests were performed by pulse electron beam heating on chemically vapor deposited coatings of TiC on Poco graphite, bulk TiC, and several kinds of isotropic graphite. The specimens were heated at various power densities (10-45 MW/m 2 ) for various pulse durations (1-2 s) to examine the dependence of thermal failures on heating conditions. The TiC coating on graphite suffered cracking, surface melting and evaporation by the thermal pulse. The surface melting limit, defined as F τ 1/2 , where F is the minimum power density that causes surface melting for a specified pulse duration τ, was approximately 48 MWs 1/2 /m 2 for the TiC coating. The combined-Carbon/Titanium ratio of the coating after electron beam heating decreased with increasing power density and pulse duration. The bulk TiC specimens were so brittle that they fractured at heat load conditions where the coating showed no damage. The graphite specimens showed sublimation as a principal damage mechanism by the thermal pulse, and the sublimation weight loss decreased with increasing the thermal conductivity of the specimen. It was confirmed that the TiC coating on graphite had favorable resistance to thermal shock as compared to the bulk TiC and that graphite with high thermal conductivity is promising material as a high heat flux component. (orig.)

Robustly Engineering Thermal Conductivity of Bilayer Graphene by Interlayer Bonding

Science.gov (United States)

Zhang, Xiaoliang; Gao, Yufei; Chen, Yuli; Hu, Ming

2016-01-01

Graphene and its bilayer structure are the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. Their realistic applications in emerging nanoelectronics usually call for thermal transport manipulation in a controllable and precise manner. In this paper we systematically studied the effect of interlayer covalent bonding, in particular different interlay bonding arrangement, on the thermal conductivity of bilayer graphene using equilibrium molecular dynamics simulations. It is revealed that, the thermal conductivity of randomly bonded bilayer graphene decreases monotonically with the increase of interlayer bonding density, however, for the regularly bonded bilayer graphene structure the thermal conductivity possesses unexpectedly non-monotonic dependence on the interlayer bonding density. The results suggest that the thermal conductivity of bilayer graphene depends not only on the interlayer bonding density, but also on the detailed topological configuration of the interlayer bonding. The underlying mechanism for this abnormal phenomenon is identified by means of phonon spectral energy density, participation ratio and mode weight factor analysis. The large tunability of thermal conductivity of bilayer graphene through rational interlayer bonding arrangement paves the way to achieve other desired properties for potential nanoelectronics applications involving graphene layers. PMID:26911859

Fast response densitometer for measuring liquid density

Science.gov (United States)

1972-01-01

Densitometer was developed which produces linear voltage proportional to changes in density of flowing liquid hydrogen. Unit has fast response time and good system stability, statistical variation, and thermal equilibrium. System accuracy is 2 percent of total density span. Basic design may be altered to include measurement of other flowing materials.

SUSY-QCD corrections to the (co)annihilation of neutralino dark matter within the MSSM

Energy Technology Data Exchange (ETDEWEB)

Meinecke, Moritz

2015-06-15

Based on experimental observations, it is nowadays assumed that a large component of the matter content in the universe is comprised of so-called cold dark matter. Furthermore, latest measurements of the temperature fluctuations of the cosmic microwave background provided an estimation of the dark matter relic density at a measurement error of one percent (concerning the experimental 1σ-error). The lightest neutralino χ 0{sub 1}, a particle which subsumes under the phenomenologically interesting category of weakly interacting massive particles, is a viable dark matter candidate for many supersymmetric (SUSY) models whose relic density Ω{sub χ} {sub 0{sub 1}} happens to lie quite naturally within the experimentally favored ballpark of dark matter. The high experimental precision can be used to constrain the SUSY parameter space to its cosmologically favored regions and to pin down phenomenologically interesting scenarios. However, to actually benefit from this progress on the experimental side it is also mandatory to minimize the theoretical uncertainties. An important quantity within the calculation of the neutralino relic density is the thermally averaged sum over different annihilation and coannihilation cross sections of the neutralino and further supersymmetric particles. It is now assumed and also partly proven that these cross sections can be subject to large loop corrections which can even shift the associated Ω{sub χ} {sub 0{sub 1}} by a factor larger than the current experimental error. However, most of these corrections are yet unknown. In this thesis, we calculate higher-order corrections for some of the most important (co)annihilation channels both within the framework of the R-parity conserving Minimal Supersymmetric Standard Model (MSSM) and investigate their impact on the final neutralino relic density Ω{sub χ} {sub 0{sub 1}}. More precisely, this work provides the full O(α{sub s}) corrections of supersymmetric quantum chromodynamics (SUSY

New equations for density, entropy, heat capacity, and potential temperature of a saline thermal fluid

Science.gov (United States)

Sun, Hongbing; Feistel, Rainer; Koch, Manfred; Markoe, Andrew

2008-10-01

A set of fitted polynomial equations for calculating the physical variables density, entropy, heat capacity and potential temperature of a thermal saline fluid for a temperature range of 0-374 °C, pressure range of 0.1-100 MPa and absolute salinity range of 0-40 g/kg is established. The freshwater components of the equations are extracted from the recently released tabulated data of freshwater properties of Wagner and Pruß [2002. The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. Journal of Physical and Chemical Reference Data 31, 387-535]. The salt water component of the equation is based on the near-linear relationship between density, salinity and specific heat capacity and is extracted from the data sets of Feistel [2003. A new extended Gibbs thermodynamic potential of seawater. Progress in Oceanography 58, 43-114], Bromley et al. [1970. Heat capacities and enthalpies of sea salt solutions to 200 °C. Journal of Chemical and Engineering Data 15, 246-253] and Grunberg [1970. Properties of sea water concentrates. In: Third International Symposium on Fresh Water from the Sea, vol. 1, pp. 31-39] in a temperature range 0-200 °C, practical salinity range 0-40, and varying pressure and is also calibrated by the data set of Millero et al. [1981. Summary of data treatment for the international high pressure equation of state for seawater. UNESCO Technical Papers in Marine Science 38, 99-192]. The freshwater and salt water components are combined to establish a workable multi-polynomial equation, whose coefficients were computed through standard linear regression analysis. The results obtained in this way for density, entropy and potential temperature are comparable with those of existing models, except that our new equations cover a wider temperature—(0-374 °C) than the traditional (0-40 °C) temperature range. One can apply these newly established equations to the calculation of in-situ or

On the Relics of Scytho-Sarmato-Alanian Vocabulary in the Toponymy of Ossetia Voprosy onomastiki, 2018, Volume 15, Issu

Directory of Open Access Journals (Sweden)

Yuri A. Dzitstsoity

2018-03-01

Full Text Available The article undertakes to pick out the oldest Scythian-Sarmatian-Alanian element in Ossetian toponymy where the appellative lexis that was lost in the language is partly retained. The reconstruction of the ancient Iranian etymons is based on strict data recordings of historical phonetics and historical morphology of the Ossetian language. As a result of the work carried out, such stems as *æf- ‘water, river’, *æfsæn- ‘the top of a mountain’, *dæj- ‘settlement’, *fi jjag- ‘(wild onion’, *fi jjag- ‘running (about water’, *ke- ‘house’, *mærg- ‘meadow’, *zæræ- ‘grass’ and others were reconstructed. Some of them are also present in the appellative lexis as elements of compounds. The analyzed information verifi es the remarkable capacity of toponymy as a keeper of the ancient lexis. And although this line of research is barely touched upon, it is already clear that the relics of the ancient Iranian lexis in the Ossetian toponymy are important both for the history of the Ossetian language and the ethnic history of Ossetia. Common Iranian lexis retained in the Ossetian toponymy came out of use at different times and for various reasons. In most cases, it was replaced by Ossetian neologisms, but some of these stems were substituted by ancient Iranian lexemes which had the status of dialectical words in the ancestor language. Therefore, the Ossetian toponymy, along with compounds and the Nart Epic language, is one of the sources for reconstruction of the ancient Iranian lexis. The geography of relic lexis is another feature of interest: these word forms are equally distributed all over the Ossetian mountain zone, regardless of the contemporary dialect variations of the Ossetian language: the toponym Zæræmæg is present both in Digoria and the Alagir gorge, the hydronym Æræf is attested in Digoria and in South Ossetia.

A comparative study on thermal, mechanical and dielectric characteristics of low density polyethylene crosslinked by radiation and chemical methods

International Nuclear Information System (INIS)

Kim, B.H.; Ling, D.Y.; Kim, J.S.

1976-01-01

A comparative study on thermal, static mechanical and dielectric characteristics were made over a temperature range of ca. 20 0 C to 320 0 C and a frequency range of KHZ band on low density polyethylene specimens crosslinked, respectively, by radiation and chemical method. The thermal property of both specimens shows that softening point appears to unchange by crosslinking however, melting and liquidizing temperatures attain rapid increase at the imitation of crosslinking. Mechanical properties show little difference to both specimens crosslinked by different method, further the behaviors were discussed in connection with the relaxation of molecular segments in amorphous phase. Dose dependent dielectric characteristics observed at ambient temperature under several fixed frequencies exhibit extremities at ca. 20 Mrad and the behaviors also were interpreted qualitatively by taking into consideration of dipole concentration change in amorphous phase together with the role of specimen geometry to the depth of oxidative layer. Observing frequency dependent dielectric characteristics, it was also proved that ionic conduction loss is appreciably greater in the specimen prepared by chemical method than that by radiation. (author)

High Thermal Conductivity Materials

CERN Document Server

Shinde, Subhash L

2006-01-01

Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm2. High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, a...

Thermal conductivity of newspaper sandwiched aerated lightweight concrete panel

Energy Technology Data Exchange (ETDEWEB)

Ng, Soon-Ching; Low, Kaw-Sai [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, Setapak, 53300 Kuala Lumpur, Wilayah Persekutuan (Malaysia)

2010-12-15

Investigation on the thermal conductivity of newspaper sandwiched aerated lightweight concrete (ALC) panels is the main purpose of this study. Various densities of ALC panels ranging from 1700, 1400 and 1100 kg/m{sup 3} with three different aerial intensities of newspaper sandwiched were produced. Investigation was limited to the effect of aerial intensity of newspaper sandwiched and the effect of density of ALC on thermal conductivity. It is found that the thermal conductivity of newspaper sandwiched ALC panels reduced remarkably compared to control ALC panels. The reduction was recorded at 18.0%, 21.8% and 20.7% correspond to densities of 1700, 1400 and 1100 kg/m{sup 3} with just a mere 0.05 g/cm{sup 2} aerial intensity of newspaper sandwiched. Newspaper sandwiched has a significant impact on the performance of thermal conductivity of ALC panels based on regression analysis. (author)

Numerical Study on Density Gradient Carbon-Carbon Composite for Vertical Launching System

Science.gov (United States)

Yoon, Jin-Young; Kim, Chun-Gon; Lim, Juhwan

2018-04-01

This study presents new carbon-carbon (C/C) composite that has a density gradient within single material, and estimates its heat conduction performance by a numerical method. To address the high heat conduction of a high-density C/C, which can cause adhesion separation in the steel structures of vertical launching systems, density gradient carbon-carbon (DGCC) composite is proposed due to its exhibiting low thermal conductivity as well as excellent ablative resistance. DGCC is manufactured by hybridizing two different carbonization processes into a single carbon preform. One part exhibits a low density using phenolic resin carbonization to reduce heat conduction, and the other exhibits a high density using thermal gradient-chemical vapor infiltration for excellent ablative resistance. Numerical analysis for DGCC is performed with a heat conduction problem, and internal temperature distributions are estimated by the forward finite difference method. Material properties of the transition density layer, which is inevitably formed during DGCC manufacturing, are assumed to a combination of two density layers for numerical analysis. By comparing numerical results with experimental data, we validate that DGCC exhibits a low thermal conductivity, and it can serve as highly effective ablative material for vertical launching systems.

Laboratory measurements of the coefficient of thermal expansion of Olkiluoto drill core samples

International Nuclear Information System (INIS)

Aakesson, U.

2012-04-01

The coefficient of thermal expansion and the wet density has been determined on 22 specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226, Olkiluoto, Finland. The coefficient of thermal expansion has been determined in the temperature interval 20-60 deg C. The results indicated that the thermal expansion was almost linear, and the coefficient of thermal expansion for the investigated specimens range between 3.2 and 14.4 x 10 -6 mm/mm deg C, and the wet density between 2,610 and 2,820 kg/m 3 . The granite pegmatite has slightly lower coefficient of thermal expansion and wet density than gneissic rocks. (orig.)

Direct and indirect detection of dissipative dark matter

Energy Technology Data Exchange (ETDEWEB)

Fan, JiJi; Katz, Andrey; Shelton, Jessie, E-mail: jijifan1982@gmail.com, E-mail: katz.andrey@gmail.com, E-mail: jshelton137@gmail.com [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)

2014-06-01

We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints.

Direct and indirect detection of dissipative dark matter

International Nuclear Information System (INIS)

Fan, JiJi; Katz, Andrey; Shelton, Jessie

2014-01-01

We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints

Remarks on saturation of energy confinement in high density regime on LHD

International Nuclear Information System (INIS)

Yamada, Hiroshi; Morita, Shigeru; Murakami, Sadayoshi

2003-01-01

A study on energy confinement times in currentless helical plasmas has indicated a preferable density dependence like τ E ∝ n-bar e 0.5-0.6 . However, saturation of energy confinement time has been often observed during the density ramping-up phase by gas puffing in NBI heated plasmas in LHD. The power balance analysis indicates that the thermal diffusivity is improved by the increase in local density while the global energy confinement time loses the dependence on the density. The flat or hollow density profile, which is distinguished in the density-ramping phase, promotes a broad heat power deposition. This change explains the apparent contradiction between the density dependence of the thermal diffusivity and the global energy confinement time. This result suggests that central heating can maintain a favorable density dependence of the energy confinement time in the high density regime. (author)

Entropy considerations in constraining the mSUGRA parameter space

International Nuclear Information System (INIS)

Nunez, Dario; Sussman, Roberto A.; Zavala, Jesus; Nellen, Lukas; Cabral-Rosetti, Luis G.; Mondragon, Myriam

2006-01-01

We explore the use of two criteria to constraint the allowed parameter space in mSUGRA models. Both criteria are based in the calculation of the present density of neutralinos as dark matter in the Universe. The first one is the usual ''abundance'' criterion which is used to calculate the relic density after the ''freeze-out'' era. To compute the relic density we used the numerical public code micrOMEGAs. The second criterion applies the microcanonical definition of entropy to a weakly interacting and self-gravitating gas evaluating then the change in the entropy per particle of this gas between the ''freeze-out'' era and present day virialized structures (i.e systems in virial equilibrium). An ''entropy-consistency'' criterion emerges by comparing theoretical and empirical estimates of this entropy. The main objective of our work is to determine for which regions of the parameter space in the mSUGRA model are both criteria consistent with the 2σ bounds according to WMAP for the relic density: 0.0945 < ΩCDMh2 < 0.1287. As a first result, we found that for A0 = 0, sgnμ +, small values of tanβ are not favored; only for tanβ ≅ 50 are both criteria significantly consistent

Thermal performance and heat transport in aquifer thermal energy storage

Science.gov (United States)

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.

Mechanical properties and thermal behaviour of LLDPE/MWNTs nanocomposites

Directory of Open Access Journals (Sweden)

Tai Jin-hua

2012-12-01

Full Text Available Multi-walled carbon nanotubes (MWNTs were incorporated into a linear low-density polyethylene (LLDPE matrix through using screw extrusion and injection technique. The effect of different weight percent loadings of MWNTs on the morphology, mechanical, and thermal of LLDPE/MWNTs nanocomposite had been investigated. It was found that, at low concentration of MWNTs, it could uniformly disperse into a linear low-density polyethylene matrix and provide LLDPE/MWNTs nanocomposites much improved mechanical properties. Thermal analysis showed that a clear improvement of thermal stability for LLDPE/MWNTs nanocomposites increased with increasing MWNTs content.

Simultaneous measurement of thermal conductivity, thermal diffusivity and prediction of effective thermal conductivity of porous consolidated igneous rocks at room temperature

International Nuclear Information System (INIS)

Aurangzeb; Ali, Zulqurnain; Gurmani, Samia Faiz; Maqsood, Asghari

2006-01-01

Thermal conductivity, thermal diffusivity and heat capacity per unit volume of porous consolidated igneous rocks have been measured, simultaneously by Gustafsson's probe at room temperature and normal pressure using air as saturant. Data are presented for eleven samples of dunite, ranging in porosity from 0.130 to 0.665% by volume, taken from Chillas near Gilgit, Pakistan. The porosity and density parameters have been measured using American Society of Testing and Materials (ASTM) standards at ambient conditions. The mineral composition of samples has been analysed from their thin sections (petrography). An empirical model to predict the thermal conductivity of porous consolidated igneous rocks is also proposed. The thermal conductivities are predicted by some of the existing models along with the proposed one. It is observed that the values of effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 6%

Enhancement in thermal and mechanical properties of bricks

Directory of Open Access Journals (Sweden)

Shibib Khalid S.

2013-01-01

Full Text Available A new type of porous brick is proposed. Sawdust is initially well mixed with wet clay in order to create voids inside the brick during the firing process. The voids will enhance the total performance of the brick due to the reduction of its density and thermal conductivity and a minor reduction of its compressive stress. All these properties have been measured experimentally and good performance has been obtained. Although a minor reduction in compressive stress has been observed with increased porosity, this property has still been larger than that of the common used hollow brick. Data obtained by this work lead to a new type of effective brick having a good performance with no possibility that mortar enters inside the holes which is the case with the common used hollow bricks. The mortar has a determent effect on thermal properties of the wall since it has some higher thermal conductivity and density than that of brick which increases the wall overall density and thermal conductivity of the wall.

Understanding the radio spectral indices of galaxy cluster relics by superdiffusive shock acceleration

Science.gov (United States)

Zimbardo, Gaetano; Perri, Silvia

2018-06-01

Galaxy cluster merger shocks are the likely source of relativistic electrons, but many observations do not fit into the standard acceleration models. In particular, there is a long-standing discrepancy between the radio derived Mach numbers M_radio and the Mach numbers derived from X-ray measurements, M_X. Here, we show how superdiffusive electron transport and superdiffusive shock acceleration (SSA) can help to solve this problem. We present a heuristic derivation of the superlinear time growth of the mean square displacement of particles, ⟨Δx2⟩∝tβ, and of the particle energy spectral index in the framework of SSA. The resulting expression for the radio spectral index α is then used to determine the superdiffusive exponent β from the observed values of α and of the compression ratio for a number of radio relics. Therefore, the fact that M_radio>M_X can be explained by SSA without the need to make assumptions on the energy spectrum of the seed electrons to be re-accelerated. We also consider the acceleration times obtained in the diffusive case, based both on the Bohm diffusion coefficient and on the quasilinear diffusion coefficient. While in the latter case the acceleration time is consistent with the estimated electron energy loss time, the former case it is much shorter.

Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

Science.gov (United States)

Elzouka, Mahmoud

This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

Ion exchange synthesis and thermal characteristics of some [N

Indian Academy of Sciences (India)

These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. Thermophysical properties such as density, coefficient of volume expansion, heat of fusion, heat capacity and thermal energy storage capacity were determined. Thermal conductivity of the samples was determined ...

Thermal Transport in Soft PAAm Hydrogels

Directory of Open Access Journals (Sweden)

Ni Tang

2017-12-01

Full Text Available As the interface between human and machine becomes blurred, hydrogel incorporated electronics and devices have emerged to be a new class of flexible/stretchable electronic and ionic devices due to their extraordinary properties, such as softness, mechanically robustness, and biocompatibility. However, heat dissipation in these devices could be a critical issue and remains unexplored. Here, we report the experimental measurements and equilibrium molecular dynamics simulations of thermal conduction in polyacrylamide (PAAm hydrogels. The thermal conductivity of PAAm hydrogels can be modulated by both the effective crosslinking density and water content in hydrogels. The effective crosslinking density dependent thermal conductivity in hydrogels varies from 0.33 to 0.51 Wm−1K−1, giving a 54% enhancement. We attribute the crosslinking effect to the competition between the increased conduction pathways and the enhanced phonon scattering effect. Moreover, water content can act as filler in polymers which leads to nearly 40% enhancement in thermal conductivity in PAAm hydrogels with water content vary from 23 to 88 wt %. Furthermore, we find the thermal conductivity of PAAm hydrogel is insensitive to temperature in the range of 25–40 °C. Our study offers fundamental understanding of thermal transport in soft materials and provides design guidance for hydrogel-based devices.

Limitations in accurate electron density studies

International Nuclear Information System (INIS)

Wal, R. van der.

1982-01-01

Most of X-ray diffraction studies are devoted to the determination of three-dimensional crystal structures from the electron density distributions. In these cases the density distributions are described by the independent atom model (IAM model), which consists of a superposition of spherically averaged free atom densities, which are smeared by thermal vibrations. During the last few decades studies have been made into the deviations of the density distribution from the IAM model, which enables a study of the chemical binding between atoms. The total density can be described using pseudo-atom multipole models as a superposition of aspherical pseudo-atom densities. A fundamental problem is that the separation of this density into an IAM and a deformation part is not unique. This thesis considers the problem and besides deformation densities from X-ray diffraction also considers the corresponding deformation electric field and deformation potential. (C.F.)

The LDMX Experiment

Directory of Open Access Journals (Sweden)

Mans Jeremiah

2017-01-01

Full Text Available The thermal-relic mechanism for the production of dark-matter in the early universe, combined with the precision measurements of the cosmic microwave background and the lack of observation of dark matter at the LHC, motivates the search for dark matter in the mass range between 1 MeV and 1 GeV. We describe the concept for the Light Dark Matter Experiment (LDMX, which could carry out such a search using the missing-momentum technique. The experiment would utilize a unique high-rate, low-current electron beam with an energy between 4 GeV and 10 GeV, and would have sensitivity to the thermal-relic hypothesis over a wide range of masses below 1 GeV.

The last refuge of mixed wino-Higgsino dark matter

Energy Technology Data Exchange (ETDEWEB)

Beneke, M. [Physik Department T31, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany); Bharucha, A. [Aix Marseille Univ, Université de Toulon, CNRS, CPT,Marseille (France); Hryczuk, A. [Department of Physics, University of Oslo,Box 1048, NO-0371 Oslo (Norway); National Centre for Nuclear Research,Hoża 69, 00-681, Warsaw (Poland); Recksiegel, S. [Physik Department T31, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany); Ruiz-Femenía, P. [Physik Department T31, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany); Departamento de Física Teórica and Instituto de Física Teórica UAM-CSIC,Universidad Autónoma de Madrid,E-28049 Madrid (Spain)

2017-01-02

We delineate the allowed parameter and mass range for a wino-like dark matter particle containing some Higgsino admixture in the MSSM by analysing the constraints from diffuse gamma-rays from the dwarf spheroidal galaxies, galactic cosmic rays, direct detection and cosmic microwave background anisotropies. A complete calculation of the Sommerfeld effect for the mixed-neutralino case is performed. We find that the combination of direct and indirect searches poses significant restrictions on the thermally produced wino-Higgsino dark matter with correct relic density. For μ>0 nearly the entire parameter space considered is excluded, while for μ<0 a substantial region is still allowed, provided conservative assumptions on astrophysical uncertainties are adopted.

Elementary Goldstone Higgs Boson and Dark Matter

DEFF Research Database (Denmark)

Alanne, Tommi; Gertov, Helene; Sannino, Francesco

2015-01-01

We investigate a perturbative extension of the Standard Model featuring elementary pseudo-Goldstone Higgs and dark matter particles. These are two of the five Goldstone bosons parametrising the SU(4)/Sp(4) coset space. They acquire masses, and therefore become pseudo-Goldstone bosons, due...... of the theory, the quantum corrections are precisely calculable. The remaining pseudo-Goldstone boson is identified with the dark matter candidate because it is neutral with respect to the Standard Model and stable. By a direct comparison with the Large Hadron Collider experiments, the model is found...... to be phenomenologically viable. Furthermore the dark matter particle leads to the observed thermal relic density while respecting the most stringent current experimental constraints....

Hunting electroweakinos at future hadron colliders and direct detection experiments

Energy Technology Data Exchange (ETDEWEB)

Cortona, Giovanni Grilli di [SISSA - International School for Advanced Studies,Via Bonomea 265, I-34136 Trieste (Italy); INFN - Sezione di Trieste,via Valerio 2, I-34127 Trieste (Italy)

2015-05-07

We analyse the mass reach for electroweakinos at future hadron colliders and their interplay with direct detection experiments. Motivated by the LHC data, we focus on split supersymmetry models with different electroweakino spectra. We find for example that a 100 TeV collider may explore Winos up to ∼7 TeV in low scale gauge mediation models or thermal Wino dark matter around 3 TeV in models of anomaly mediation with long-lived Winos. We show moreover how collider searches and direct detection experiments have the potential to cover large part of the parameter space even in scenarios where the lightest neutralino does not contribute to the whole dark matter relic density.

Relic gravitational waves with a running spectral index and its constraints at high frequencies

International Nuclear Information System (INIS)

Tong, M. L.; Zhang, Y.

2009-01-01

We study the impact of a running index α t on the spectrum of relic gravitational waves (RGWs) over the whole range of frequency (10 -18 ∼10 10 ) Hz and reveal its implications in RGWs detections and in cosmology. Analytical calculations show that, although the spectrum of RGWs on low frequencies is less affected by α t ≠0, on high frequencies, the spectrum is modified substantially. Investigations are made toward potential detections of the α t -modified RGWs for several kinds of current and planned detectors. The Advanced LIGO will likely be able to detect RGWs with α t ≥0 for inflationary models with the inflation index β=-1.956 and the tensor-scalar ratio r=0.55. The future LISA can detect RGWs for a much broader range of (α t ,β,r), and will have a better chance to break a degeneracy between them. Constraints on α t are estimated from several detections and cosmological observations. Among them, the most stringent one is from the bound of the big bang nucleosynthesis, and requires α t s to be of the same magnitude as α t , if both RGWs and scalar perturbations are generated by the same scalar inflation.

Gas-thermal coating of powdered materials. Communication 2

International Nuclear Information System (INIS)

Ermakov, S.S.

1986-01-01

This paper investigates the microstructure, microhardness, chemical composition of the transition zone, and also the strength characteristics of gas-thermal coatings including their adhesive power to the substrate (iron brand NC 100.24) and the residual stresses in the coatings. The microstructure of the transition zone was investigated; it was established that on the side of the substrate its density is greater than the mean density of both types of coating. It is shown that the porosity of the substrate has a competing effect on the thermal interaction of materials. Discovered regularities lead to the conclusion that the process of gas-thermal coating of powdered materials is more effective than when compact materials are coated; most effective is the combination of gas-thermal coating with processes of heat treatment of powder-metallurgy products

Thermally driven convective cells and tokamak edge turbulence

International Nuclear Information System (INIS)

Thayer, D.R.; Diamond, P.H.

1987-07-01

A unified theory for the dynamics of thermally driven convective cell turbulence is presented. The cells are excited by the combined effects of radiative cooling and resistivity gradient drive. The model also includes impurity dynamics. Parallel thermal and impurity flows enhanced by turbulent radial duffusion regulate and saturate overlapping cells, even in regimes dominated by thermal instability. Transport coefficients and fluctuation levels characteristic of the saturated turbulence are calculated. It is found that the impurity radiation increases transport coefficients for high density plasmas, while the parallel conduction damping, elevated by radial diffusion, in turn quenches the thermal instability. The enhancement due to radiative cooling provides a resolution to the dilemma of explaining the experimental observation that potential fluctuations exceed density fluctuations in the edge plasma (e PHI/T/sub e/ > n/n 0 )

A HISTORICAL PERSPECTIVE OF NUCLEAR THERMAL HYDRAULICS

Energy Technology Data Exchange (ETDEWEB)

D’Auria, F; Rohatgi, Upendra S.

2017-01-12

The nuclear thermal-hydraulics discipline was developed following the needs for nuclear power plants (NPPs) and, to a more limited extent, research reactors (RR) design and safety. As in all other fields where analytical methods are involved, nuclear thermal-hydraulics took benefit of the development of computers. Thermodynamics, rather than fluid dynamics, is at the basis of the development of nuclear thermal-hydraulics together with the experiments in complex two-phase situations, namely, geometry, high thermal density, and pressure.

Thermal diffusivity and thermal conductivity of (Th,U)O2 fuels

International Nuclear Information System (INIS)

Sengupta, A.K.; Jarvis, T.; Nair, M.R.; Ramachandran, R.; Mujumdar, S.; Purushotham, D.S.C.

2000-05-01

India has vast reserves of thorium (> 460,000 tons) and sustained work on all aspects of thorium utilization has been initiated. In this context work on fabrication of sintered thoria and mixed (Th,U)O 2 pellets and evaluation of their thermophysical properties have been taken up in Radiometallurgy Division. Thermal conductivity, being the most important thermal properties, has been calculated using the experimentally measured thermal diffusivity, density and literature values of specific heats for ThO 2 and thoria containing 2,4,6,10 and 20% UO 2 . Thermal diffusivity was measured experimentally by the laser flash method from 600 to 1600 deg C in vacuum. It was observed that thermal conductivity of ThO 2 and mixed (Th,U)O 2 decrease with increase in temperature. It was also observed that the conductivity decreases with increase in UO 2 content, the decrease being more at lower temperature than that at higher temperatures. Empirical relations correlating thermal conductivity to temperatures have been generated by the least square fit method and reported. (author)

Thermalization through parton transport

International Nuclear Information System (INIS)

Zhang Bin

2010-01-01

A radiative transport model is used to study kinetic equilibration during the early stage of a relativistic heavy ion collision. The parton system is found to be able to overcome expansion and move toward thermalization via parton collisions. Scaling behaviors show up in both the pressure anisotropy and the energy density evolutions. In particular, the pressure anisotropy evolution shows an approximate α s scaling when radiative processes are included. It approaches an asymptotic time evolution on a time scale of 1 to 2 fm/c. The energy density evolution shows an asymptotic time evolution that decreases slower than the ideal hydro evolution. These observations indicate that partial thermalization can be achieved and viscosity is important for the evolution during the early longitudinal expansion stage of a relativistic heavy ion collision.

Merger of waste in kaolin panels medium density

International Nuclear Information System (INIS)

Bezerra, A.F.C.; Santana, L.N.L.; Neves, G.A.

2011-01-01

Medium-density panels are molded under pressure and temperature and have physical and mechanical properties similar to those of solid wood. Their composition involves fibers of eucalyptus and pine, but other residues as kaolin waste can be incorporated. The objective was to manufacture medium density panels incorporating kaolin waste and compare the physical, chemical and mechanical properties of these with other commercials. The residue was subjected to the following characterization tests: X-ray diffraction, chemical analysis, differential thermal analysis, thermal gravimetric analysis and size analysis.Through the process of pressing the samples were prepared, they were evaluated for their flexural strength and tensile strength perpendicular to the water absorption / swelling in thickness, density and moisture content. According to the analyzed results, we conclude that samples having the residue had lower levels of swelling, tensile and flexural strength and higher levels of absorption.(author)

Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partner

Energy Technology Data Exchange (ETDEWEB)

Abe, Tomohiro [Institute for Advanced Research, Nagoya University,Nagoya 464-8602 (Japan); Kobayashi-Maskawa Institute for the Origin of Particles and the Universe,Nagoya University, Nagoya 464-8602 (Japan); Kawamura, Junichiro [Department of Physics, Waseda University,Tokyo 169-8555 (Japan); Okawa, Shohei [Department of Physics, Nagoya University,Nagoya 464-8602 (Japan); Omura, Yuji [Kobayashi-Maskawa Institute for the Origin of Particles and the Universe,Nagoya University, Nagoya 464-8602 (Japan)

2017-03-10

In the scenario that dark matter (DM) is a weakly interacting massive particle, there are many possibilities of the interactions with the Standard Model (SM) particles to achieve the relic density of DM. In this paper, we consider a simple DM model where the DM candidate is a complex scalar boson. The model contains a new complex gauge singlet scalar boson and a new fermion whose gauge charge is the same as the right-handed down-type quark. We dub the new fermion the bottom partner. These new particles have Yukawa interactions with the SM down-type quarks. The DM candidate interacts with the SM particles through the Yukawa interactions. The Yukawa interactions are not only relevant to the annihilation process of the DM but also contribute to the flavor physics, such as the ΔF=2 processes. In addition, the flavor alignment of the Yukawa couplings is related to the decay modes of the bottom partner, and thus we can find the explicit correlations among the physical observables in DM physics, flavor physics, and the signals at the LHC. We survey the ΔF=2 processes based on the numerical analyses of the thermal relic density, the direct detection of the DM, and the current LHC bounds. We investigate the perturbative bound on the Yukawa coupling as well. A Study of a fermionic DM model with extra scalar quarks is also given for comparison.

High-density kaonic-proton matter (KPM) composed of Λ* ≡ K-p multiplets and its astrophysical connections

Science.gov (United States)

Akaishi, Yoshinori; Yamazaki, Toshimitsu

2017-11-01

We propose and examine a new form of high-density neutral composite of Λ* ≡K- p = (s u bar) ⊗ (uud), which may be called anti-Kaonic Proton Matter (KPM), or simply, Λ*-Matter, where substantial shrinkage of baryonic bound systems originating from the strong attraction of the (K bar N) I = 0 interaction takes place, providing a ground-state neutral baryonic system with a large energy gap. The mass of an ensemble of (K-p)m, where m, the number of the K- p pair, becomes larger than m ≈ 10, is predicted to drop down below that of its corresponding neutron ensemble, (n)m, since the attractive interaction is further increased by the Heitler-London type molecular covalency as well as by chiral symmetry restoration of the QCD vacuum. Since the seed clusters (K- p, K- pp and K-K- pp) are short-lived, the formation of such a stabilized relic ensemble, (K-p)m, may be conceived during the Big-Bang Quark Gluon Plasma (QGP) period in the early universe. At the final stage of baryogenesis a substantial amount of primordial (u bar , d bar)'s are transferred and captured into KPM, where the anti-quarks find places to survive forever. The expected KPM state may be cold, dense and neutral q bar q-hybrid (Quark Gluon Bound (QGB)) states,[ s (u bar ⊗ u) ud ] m, to which the relic of the disappearing anti-quarks plays an essential role as hidden components. KPM may also be produced during the formation and decay of neutron stars in connections with supernova explosions, and other forms may exist as strange quark matter in cosmic dusts.

Enhancing radiative energy transfer through thermal extraction

Science.gov (United States)

Tan, Yixuan; Liu, Baoan; Shen, Sheng; Yu, Zongfu

2016-06-01

Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a). In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics. Thermal extraction works by using a specially designed thermal extractor to convert and guide the near-field energy to the far field, as shown in Fig. 1b. The same blackbody as shown in Fig. 1a is placed closely below the thermal extractor with a spacing smaller than the thermal wavelength. The near-field coupling transfers radiative energy with a density greater than σT4. The thermal extractor, made from transparent and high-index or structured materials, does not emit or absorb any radiation. It transforms the near-field energy and sends it toward the far field. As a result, the total amount of far-field radiative heat dissipated by the same blackbody is greatly enhanced above SσT4, where S is the area of the emitter. This paper will review the progress in thermal

Information loss in effective field theory: Entanglement and thermal entropies

Science.gov (United States)

Boyanovsky, Daniel

2018-03-01

Integrating out high energy degrees of freedom to yield a low energy effective field theory leads to a loss of information with a concomitant increase in entropy. We obtain the effective field theory of a light scalar field interacting with heavy fields after tracing out the heavy degrees of freedom from the time evolved density matrix. The initial density matrix describes the light field in its ground state and the heavy fields in equilibrium at a common temperature T . For T =0 , we obtain the reduced density matrix in a perturbative expansion; it reveals an emergent mixed state as a consequence of the entanglement between light and heavy fields. We obtain the effective action that determines the time evolution of the reduced density matrix for the light field in a nonperturbative Dyson resummation of one-loop correlations of the heavy fields. The Von-Neumann entanglement entropy associated with the reduced density matrix is obtained for the nonresonant and resonant cases in the asymptotic long time limit. In the nonresonant case the reduced density matrix displays an incipient thermalization albeit with a wave-vector, time and coupling dependent effective temperature as a consequence of memory of initial conditions. The entanglement entropy is time independent and is the thermal entropy for this effective, nonequilibrium temperature. In the resonant case the light field fully thermalizes with the heavy fields, the reduced density matrix loses memory of the initial conditions and the entanglement entropy becomes the thermal entropy of the light field. We discuss the relation between the entanglement entropy ultraviolet divergences and renormalization.

Distributed thermal micro sensors for fluid flow

NARCIS (Netherlands)

van Baar, J.J.J.

2002-01-01

In this thesis thermal sensor-actuator structures are proposed for measuring the parameters pressure p, dynamic viscosity μ, thermal conductivity , specific heat c, density and the fluid velocity v. In this chapter examples will be given of the added value of many identical simple elements and the

Correlated density matrix theory of spatially inhomogeneous Bose fluids

International Nuclear Information System (INIS)

Gernoth, K.A.; Clark, J.W.; Ristig, M.L.

1994-06-01

In this paper, the variational Hartree-Jastrow theory of the ground state of spatially inhomogeneous Bose systems is extended to finite temperatures. The theory presented here is a generalization also in the sense that it extends the correlated density matrix approach, formulated previously for uniform Bose fluids, to systems with nonuniform density profiles. The method provides a framework in which the effects of thermal excitations on the spatial structure of a Bose fluid, as represented by the density profile and the two-body distribution functions, may be discussed on the basis on an ab initio microscopic description of the system. Thermal excitations make their appearance through self-consistently determined one-body and two-body potentials which enter the nonlinear, coupled Euler-Lagrange equations for the one-body density and for the pair distribution function. Since back-flow correlations are neglected, the excitations are described by a Feynman eigenvalue equation, suitably generalized to nonzero temperatures. The only external quantities entering the correlated density matrix theory elaborated here are the bare two-body interaction potential and, in actual applications, the boundary conditions to be imposed on the one-body density. 30 refs

Burn propagation in a PBX 9501 thermal explosion

International Nuclear Information System (INIS)

Henson, B. F.; Smilowitz, L.; Romero, J. J.; Sandstrom, M. M.; Asay, B. W.; Schwartz, C.; Saunders, A.; Merrill, F.; Morris, C.; Murray, M. M.; McNeil, W. V.; Marr-Lyon, M.; Rightley, P. M.

2007-01-01

We have applied proton radiography to study the conversion of solid density to gaseous combustion products subsequent to ignition of a thermal explosion in PBX 9501. We apply a thermal boundary condition to the cylindrical walls of the case, ending with an induction period at 205 C. We then introduce a laser pulse that accelerates the thermal ignition and synchronizes the explosion with the proton accelerator. We then obtain fast, synchronized images of the evolution of density loss with few microsecond resolution during the approximately 100 microsecond duration of the explosion. We present images of the solid explosive during the explosion and discuss measured rates and assumed mechanisms of burning the role of pressure in this internal burning

TRIGA research reactors with higher power density

International Nuclear Information System (INIS)

Whittemore, W.L.

1994-01-01

The recent trend in new or upgraded research reactors is to higher power densities (hence higher neutron flux levels) but not necessarily to higher power levels. The TRIGA LEU fuel with burnable poison is available in small diameter fuel rods capable of high power per rod (≅48 kW/rod) with acceptable peak fuel temperatures. The performance of a 10-MW research reactor with a compact core of hexagonal TRIGA fuel clusters has been calculated in detail. With its light water coolant, beryllium and D 2 O reflector regions, this reactor can provide in-core experiments with thermal fluxes in excess of 3 x 10 14 n/cm 2 ·s and fast fluxes (>0.1 MeV) of 2 x 10 14 n/cm 2 ·s. The core centerline thermal neutron flux in the D 2 O reflector is about 2 x 10 14 n/cm 2 ·s and the average core power density is about 230 kW/liter. Using other TRIGA fuel developed for 25-MW test reactors but arranged in hexagonal arrays, power densities in excess of 300 kW/liter are readily available. A core with TRIGA fuel operating at 15-MW and generating such a power density is capable of producing thermal neutron fluxes in a D 2 O reflector of 3 x 10 14 n/cm 2 ·s. A beryllium-filled central region of the core can further enhance the core leakage and hence the neutron flux in the reflector. (author)

Densities of Pb-Sn alloys during solidification

Science.gov (United States)

Poirier, D. R.

1988-01-01

Data for the densities and expansion coefficients of solid and liquid alloys of the Pb-Sn system are consolidated in this paper. More importantly, the data are analyzed with the purpose of expressing either the density of the solid or of the liquid as a function of its composition and temperature. In particular, the densities of the solid and of the liquid during dendritic solidification are derived. Finally, the solutal and thermal coefficients of volume expansion for the liquid are given as functions of temperature and composition.

Low-temperature densification and excellent thermal properties of W–Cu thermal-management composites prepared from copper-coated tungsten powders

International Nuclear Information System (INIS)

Zhang, Lianmeng; Chen, Wenshu; Luo, Guoqiang; Chen, Pingan; Shen, Qiang; Wang, Chuanbin

2014-01-01

Highlights: • High-density (98.4%) W–20 wt.%Cu composites were low-temperature fabricated. • A highly pure Cu network and a homogenous microstructure formed in the composites. • The interfaces between W and Cu are well bonded with no spaces. • The composites have excellent thermal properties. -- Abstract: High-density W–20 wt.%Cu composites containing a Cu-network structure and exhibiting good thermal properties were fabricated by low-temperature hot-press sintering from high-purity copper-coated tungsten powders. The relative density of W–20 wt.%Cu composites sintered at 950 °C–100 MPa–2 h was 98.4%. The low-temperature densification of W–Cu composites occurs because the sintering mode of the coated particles involves only sintering of Cu to Cu, rather than both Cu to W and Cu to Cu, as required for conventional powder particles. The microstructure shows that a network of high-purity Cu extends throughout the composites, and that the W is distributed homogeneously; the interfaces between W and Cu show good contact. The composites have excellent thermal conductivity (239 W/(m K)) and a relatively low coefficient of thermal expansion (7.4 × 10 −6 /K), giving them some of the best properties reported to date for thermal-management materials. The excellent performance is mainly because of their structure, which arises from the characteristics of the high-purity copper-coated tungsten powders

Thermal conductivity of compacted bentonite as a buffer material for a high-level radioactive waste repository

International Nuclear Information System (INIS)

Lee, Jae Owan; Choi, Heuijoo; Lee, Jong Youl

2016-01-01

Highlights: • The thermal conductivities were measured under various disposal conditions. • They were significantly influenced by the water content and dry density. • They were not sensitive to the temperature and the anisotropic structure. • A new model of thermal conductivity was proposed for the thermal analysis. - Abstract: Bentonite buffer is one of the major barrier components of a high-level radioactive waste (HLW) repository, and the thermal conductivity of the bentonite buffer is a key parameter for the thermal performance assessment of the HLW repository. This study measured the thermal conductivity of compacted bentonite as a buffer material and investigated its dependence upon various disposal conditions: the dry density, water content, anisotropic structure of the compacted bentonite, and temperature. The measurement results showed that the thermal conductivity was significantly influenced by the water content and dry density of the compacted bentonite, while there was not a significant variation with respect to the temperature. The anisotropy of the thermal conductivity had a negligible variation for an increasing dry density. The present study also proposed a geometric mean model of thermal conductivity which best fits the experimental data.

Transient thermal camouflage and heat signature control

Science.gov (United States)

Yang, Tian-Zhi; Su, Yishu; Xu, Weikai; Yang, Xiao-Dong

2016-09-01

Thermal metamaterials have been proposed to manipulate heat flux as a new way to cloak or camouflage objects in the infrared world. To date, however, thermal metamaterials only operate in the steady-state and exhibit detectable, transient heat signatures. In this letter, the theoretical basis for a thermal camouflaging technique with controlled transient diffusion is presented. This technique renders an object invisible in real time. More importantly, the thermal camouflaging device instantaneously generates a pre-designed heat signature and behaves as a perfect thermal illusion device. A metamaterial coating with homogeneous and isotropic thermal conductivity, density, and volumetric heat capacity was fabricated and very good camouflaging performance was achieved.

Thermal Diffusivity and Thermal Conductivity of Dispersed Glass Sphere Composites Over a Range of Volume Fractions

Science.gov (United States)

Carson, James K.

2018-06-01

Glass spheres are often used as filler materials for composites. Comparatively few articles in the literature have been devoted to the measurement or modelling of thermal properties of composites containing glass spheres, and there does not appear to be any reported data on the measurement of thermal diffusivities over a range of filler volume fractions. In this study, the thermal diffusivities of guar-gel/glass sphere composites were measured using a transient comparative method. The addition of the glass beads to the gel increased the thermal diffusivity of the composite, more than doubling the thermal diffusivity of the composite relative to the diffusivity of the gel at the maximum glass volume fraction of approximately 0.57. Thermal conductivities of the composites were derived from the thermal diffusivity measurements, measured densities and estimated specific heat capacities of the composites. Two approaches to modelling the effective thermal diffusivity were considered.

Nonlinear thermal reduced model for Microwave Circuit Analysis

OpenAIRE

Chang, Christophe; Sommet, Raphael; Quéré, Raymond; Dueme, Ph.

2004-01-01

With the constant increase of transistor power density, electro thermal modeling is becoming a necessity for accurate prediction of device electrical performances. For this reason, this paper deals with a methodology to obtain a precise nonlinear thermal model based on Model Order Reduction of a three dimensional thermal Finite Element (FE) description. This reduced thermal model is based on the Ritz vector approach which ensure the steady state solution in every case. An equi...

Flatness of the universe - Reconciling theoretical prejudices with observational data

Science.gov (United States)

Turner, M. S.; Steigman, G.; Krauss, L. M.

1984-01-01

Theoretical prejudices argue strongly for a flat universe; however, observations do not support this view. It is pointed out that this apparent conflict could be resolved if the mass density of the universe today were dominated by (1) relativistic particles produced by the recent decay of massive, relic particle species, or by (2) a relic cosmological constant. Scenario (1) has several advantages in the context of galaxy formation, but must confront the problem of a young universe.

Swelling behavior of several bituminous coals and their thermally treated coals

Energy Technology Data Exchange (ETDEWEB)

Shui, Heng-fu; Cao, Mei-xia; Wang, Zhi-cai [Anhui University of Technology, Maanshan (China). School of Chemistry & Chemical Engineering

2007-07-01

The swelling behavior in different solvents of 4 bituminous coals with different ranks and their residues from extraction by CS{sub 2}/NMP mixed solvent (l:1 in volume) were measured. The change in swelling property of the four coals thermally treated at different temperature was observed. The results show that the swelling ratio decreases with increasing rank of coal. For lower rank bituminous coals the swelling ratios in polar solvent are higher than those in non-polar solvent, and this difference decreases with increasing rank. The cross-linking densities of the four residues decrease, and the swelling ratios increase compared with those of raw coals. The swelling ratios of the four thermally treated coals under 150{sup o}C in CS{sub 2} increase, suggesting the decrease in crosslinking density of them. When the thermal treatment temperature increases to 240{sup o}C, the swelling rations of the other three coals in NMP and CS{sub 2} increase again except gas coal, demonstrating the further decrease in crosslinking density. This result is coincident with the extraction yield change in the mixed solvent of the thermally treated coal. For example, the extraction yield of lean coal treated at 240{sup o}C increases from 6.9% to 17.3%. FT-IR results show the removal of oxygen group of the thermally treated coals. This may explain the increase in swelling ratio and extraction yield in the mixed solvent of coal after thermal treatment. The cross-linking density of the thermally treated coal decreases because of the break of hydrogen bonds due to removal of C = 0 and -OH oxygen groups during the thermal treatment, resulting in the increases of swelling ratio and extraction yield in the mixed solvent of thermally treated coal compared with those of raw coal. 15 refs., 3 figs., 6 tabs.

Density, thermal expansion coefficient and viscosity of sodium tetraborate (borax)-UO2 and of sodium metaborate-UO2 solutions at high temperatures

International Nuclear Information System (INIS)

Dalle Donne, M.; Dorner, S.; Roth, A.

1983-01-01

Measurements have been performed of the density, of the volumetric thermal expansion coefficient and of the viscosity of liquid sodium tetraborate (borax) and of sodium metaborate both pure and with two different amounts of UO 2 dissolved in each. The viscosity measurements have been performed for the solution of sodium tetraborate with UO 2 and CeO 2 , and with CeO 2 only as well. These data are required for the design of core-catchers based on sodium borates. The density measurements have been performed with the buoyancy method in the temperature range from 825 0 C to 1300 0 C, the viscosity measurements in the temperature range 700-1250 0 C with a modified Haake viscosity balance. The balance was previously calibrated at ambient temperature with a standard calibration liquid and at high temperatures, with data for pure borax available from the literature. (orig.)

Thermal conductivity of sputtered amorphous Ge films

International Nuclear Information System (INIS)

Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

2014-01-01

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

High-density kaonic-proton matter (KPM composed of Λ⁎≡K−p multiplets and its astrophysical connections

Directory of Open Access Journals (Sweden)

Yoshinori Akaishi

2017-11-01

Full Text Available We propose and examine a new form of high-density neutral composite of Λ⁎≡K−p=(su¯⊗(uud, which may be called anti-Kaonic Proton Matter (KPM, or simply, Λ⁎-Matter, where substantial shrinkage of baryonic bound systems originating from the strong attraction of the (K¯NI=0 interaction takes place, providing a ground-state neutral baryonic system with a large energy gap. The mass of an ensemble of (K−pm, where m, the number of the K−p pair, becomes larger than m≈10, is predicted to drop down below that of its corresponding neutron ensemble, (nm, since the attractive interaction is further increased by the Heitler–London type molecular covalency as well as by chiral symmetry restoration of the QCD vacuum. Since the seed clusters (K−p, K−pp and K−K−pp are short-lived, the formation of such a stabilized relic ensemble, (K−pm, may be conceived during the Big-Bang Quark Gluon Plasma (QGP period in the early universe. At the final stage of baryogenesis a substantial amount of primordial (u¯,d¯'s are transferred and captured into KPM, where the anti-quarks find places to survive forever. The expected KPM state may be cold, dense and neutral q¯q-hybrid (Quark Gluon Bound (QGB states, [s(u¯⊗uud]m, to which the relic of the disappearing anti-quarks plays an essential role as hidden components. KPM may also be produced during the formation and decay of neutron stars in connections with supernova explosions, and other forms may exist as strange quark matter in cosmic dusts.

Thermal compatibility of U-2wt.%Mo and U-10wt.%Mo fuel prepared by centrifugal atomization for high density research reactor fuels

International Nuclear Information System (INIS)

Kim Ki Hwan; Lee Don Bae; Kim Chang Kyu; Kuk Il Hyun; Hofman, G.E.

1997-01-01

Research on the intermetallic compounds of uranium was revived in 1978 with the decision by the international research reactor community to develop proliferation-resistant fuels. The reduction of 93% 235 U (HEU) to 20% 235 U (LEU) necessitates the use of higher U-loading fuels to accommodate the addition 238 U in the LEU fuels. While the vast majority of reactors can be satisfied with U 3 Si 2 -Al dispersion fuel, several high performance reactors require high loadings of up to 8-9 g U cm -3 . Consequently, in the renewed fuel development program of the Reduced Enrichment for Research and Test Reactors (RERTR) Program, attention has shifted to high density uranium alloys. Early irradiation experiments with uranium alloys showed promise of acceptable irradiation behavior, if these alloys can be maintained in their cubic γ-U crystal structure. It has been reported that high density atomized U-Mo powders prepared by rapid cooling have metastable isotropic γ-U phase saturated with molybdenum, and good γ-U phase stability, especially in U-10wt.%Mo alloy fuel. If the alloy has good thermal compatibility with aluminium, and this metastable gamma phase can be maintained during irradiation, U-Mo alloy would be a prime candidate for dispersion fuel for research reactors. In this paper, U-2w.%Mo and U-10w.%Mo alloy powder which have high density (above 15 g-U/cm 3 ), are prepared by centrifugal atomization. The U-Mo alloy fuel meats are made into rods extruding the atomized powders. The characteristics related to the thermal compatibility of U-2w.%Mo and U-10w.%Mo alloy fuel meat at 400 o C for time up to 2000 hours are examined. (author)

Supersymmetric QCD corrections and phenomenological studies in relation to coannihilation of dark matter

Energy Technology Data Exchange (ETDEWEB)

Harz, Julia

2013-11-15

In this thesis, we assume a minimal supersymmetric extension of the Standard Model (MSSM) with conserved R-parity such that the lightest neutralino is the cold dark matter candidate. A stringent constraint on the MSSM parameter space can be set by the comparison of the predicted neutralino relic density with the experimentally determined value. In order to match the high experimental precision, uncertainties within the theoretical calculation have to be reduced. One of the main uncertainties arises from the cross section of annihilation and coannihilation processes of the dark matter particle. In a phenomenological study we investigate the interplay of neutralino-neutralino annihilation, neutralino-stop coannihilation and stop-stop annihilation. We demonstrate that neutralino-stop coannihilation contributes significantly to the neutralino relic density and is furthermore very well motivated due to the recent discovery of a 125 GeV Higgs boson. Due to this ample motivation we have calculated the full O({alpha}{sub s}) supersymmetric QCD corrections to neutralino-squark coannihilation. We show in detail our DR/on-shell renormalization scheme for the treatment of ultraviolet divergences, and describe the phase space slicing method which is used to handle soft and collinear infrared divergences. Further, we comment on the treatment of occurring intermediate onshell states. The whole calculation is provided within the numerical tool DM rate at NLO that serves as an extension to existing relic density calculators, which consider only an effective tree-level calculation. Based on three example scenarios we study the impact of the NLO corrections on the total (co)annihilation cross section, and observe corrections of up to 30 %. This leads to a correction of 5 - 9 % on the relic density, which is larger than the current experimental uncertainty and is, thus, important to be taken into account.

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

Science.gov (United States)

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.

Spectrum of perturbations arising in a nonsingular model of the Universe with the initial de Sitter stage and the anisotropy of the relic radiation

International Nuclear Information System (INIS)

Starobinskij, A.A.

1983-01-01

Spectrum of primary adiabatic perturbations and gravitational waves formed in the proposed earlier by the author nonsingular cosmological model with the initial quantum de Sitter stage generated by gravitational vacuum polarization is calculated. The spectrum of gravitational waves appears to be flat, the spectrum of adiabatic perturbations is close to the flat one. The large-scale anisotropy of the temperature T of the relic electromagnetic radiation due to these fluctuations is found. It is shown that the most promising way to detect the anisotropy in the case of a flat perturbation spectrum is the investigation of correlations of ΔT/T at the angles of 5 deg - 10 deg

Simplified models of mixed dark matter

International Nuclear Information System (INIS)

Cheung, Clifford; Sanford, David

2014-01-01

We explore simplified models of mixed dark matter (DM), defined here to be a stable relic composed of a singlet and an electroweak charged state. Our setup describes a broad spectrum of thermal DM candidates that can naturally accommodate the observed DM abundance but are subject to substantial constraints from current and upcoming direct detection experiments. We identify ''blind spots'' at which the DM-Higgs coupling is identically zero, thus nullifying direct detection constraints on spin independent scattering. Furthermore, we characterize the fine-tuning in mixing angles, i.e. well-tempering, required for thermal freeze-out to accommodate the observed abundance. Present and projected limits from LUX and XENON1T force many thermal relic models into blind spot tuning, well-tempering, or both. This simplified model framework generalizes bino-Higgsino DM in the MSSM, singlino-Higgsino DM in the NMSSM, and scalar DM candidates that appear in models of extended Higgs sectors

Photoswitchable Molecular Rings for Solar-Thermal Energy Storage.

Science.gov (United States)

Durgun, E; Grossman, Jeffrey C

2013-03-21

Solar-thermal fuels reversibly store solar energy in the chemical bonds of molecules by photoconversion, and can release this stored energy in the form of heat upon activation. Many conventional photoswichable molecules could be considered as solar thermal fuels, although they suffer from low energy density or short lifetime in the photoinduced high-energy metastable state, rendering their practical use unfeasible. We present a new approach to the design of chemistries for solar thermal fuel applications, wherein well-known photoswitchable molecules are connected by different linker agents to form molecular rings. This approach allows for a significant increase in both the amount of stored energy per molecule and the stability of the fuels. Our results suggest a range of possibilities for tuning the energy density and thermal stability as a function of the type of the photoswitchable molecule, the ring size, or the type of linkers.

Thermal conductivity of 238PuO2 powder, intermediates, and dense fuel forms

International Nuclear Information System (INIS)

Bickford, D.F.; Crain, B. Jr.

1975-10-01

The thermal conductivities of porous 238 PuO 2 powder (calcined oxalate), milled powder, and high-density granules were calculated from direct measurements of steady-state temperature profiles resulting from self-heating. Thermal conductivities varied with density, temperature, and gas content of the pores. Errors caused by thermocouple heat conduction were less than 5 percent when the dimensions of the thermal conductivity cell and the thermocouple were properly selected

Overview of thermal conductivity models of anisotropic thermal insulation materials

Science.gov (United States)

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.

Parametric studies and optimisation of pumped thermal electricity storage

International Nuclear Information System (INIS)

McTigue, Joshua D.; White, Alexander J.; Markides, Christos N.

2015-01-01

Highlights: • PTES is modelled by cycle analysis and a Schumann-style model of the thermal stores. • Optimised trade-off surfaces show a flat efficiency vs. energy density profile. • Overall roundtrip efficiencies of around 70% are not inconceivable. - Abstract: Several of the emerging technologies for electricity storage are based on some form of thermal energy storage (TES). Examples include liquid air energy storage, pumped heat energy storage and, at least in part, advanced adiabatic compressed air energy storage. Compared to other large-scale storage methods, TES benefits from relatively high energy densities, which should translate into a low cost per MW h of storage capacity and a small installation footprint. TES is also free from the geographic constraints that apply to hydro storage schemes. TES concepts for electricity storage rely on either a heat pump or refrigeration cycle during the charging phase to create a hot or a cold storage space (the thermal stores), or in some cases both. During discharge, the thermal stores are depleted by reversing the cycle such that it acts as a heat engine. The present paper is concerned with a form of TES that has both hot and cold packed-bed thermal stores, and for which the heat pump and heat engine are based on a reciprocating Joule cycle, with argon as the working fluid. A thermodynamic analysis is presented based on traditional cycle calculations coupled with a Schumann-style model of the packed beds. Particular attention is paid to the various loss-generating mechanisms and their effect on roundtrip efficiency and storage density. A parametric study is first presented that examines the sensitivity of results to assumed values of the various loss factors and demonstrates the rather complex influence of the numerous design variables. Results of an optimisation study are then given in the form of trade-off surfaces for roundtrip efficiency, energy density and power density. The optimised designs show a

Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model

Energy Technology Data Exchange (ETDEWEB)

Biswas, Anirban; Gupta, Aritra [Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad 211 019 (India)

2016-09-27

With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

Measurement of x-ray emission and thermal transport in near-solid-density plasmas heated by 130 fs laser pulses

International Nuclear Information System (INIS)

Young, B.K.; Wilson, B.G.; Price, D.F.; Stewart, R.E.

1998-01-01

Near-solid-density plasmas with peak temperatures of 370±50 eV have been generated using a high-contrast (∼10 -7 ), 400 nm, 130 fs laser pulse of intensity 3x10 17 Wcm -2 at the Ultrashort Pulse Laser at Lawrence Livermore National Laboratory. The x-ray-emission spectra from thin tracer layers of germanium, tamped by layers of plastic, were measured as a function of target depth. The results qualitatively agree with calculations based on detailed local thermodynamic equilibrium (LTE) and modified non-LTE spectroscopic opacity models using plasma conditions determined using LASNEX hydrodynamic simulations. No evidence of thermal flux inhibition into the bulk target material was observed. The experiments and detailed simulations are presented. copyright 1998 The American Physical Society

Evaluation of neutron flux density and power density with SPN-detectors and micro calorimeters

International Nuclear Information System (INIS)

Gehre, G.; Rindelhardt, U.; Seidenkranz, T.; Hogel, J.; Jirousek, V.; Vazek, J.

1983-02-01

During investigations with a special equipped fuel assembly in the Rheinsberg nuclear power station the neutron flux and the power density were evaluated from measurements with SPN-detectors and micro calorimeters. The reliability of both detector types, their measurement accuracy under different physical conditions and the usefulness of the developed calculation models are discussed in detail. The thermal flux and the power density evaluated with SPND's agree well with theoretical results. The values obtained through micro calorimeter measurements are systematic lower by about 18%. This deviation is probably a result of differences in the used calculation models. (author)

Density, thermal expansion and viscosity of cholinium-derived ionic liquids.

Science.gov (United States)

Costa, Anabela J L; Soromenho, Mário R C; Shimizu, Karina; Marrucho, Isabel M; Esperança, José M S S; Lopes, José N Canongia; Rebelo, Luís Paulo N

2012-05-14

Density and viscosity data of the N-alkyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ionic liquids homologous series [N(1 1 n 2(OH))][Ntf(2)] with n=1, 2, 3, 4 and 5 have been measured at atmospheric pressure in the 283density, viscosity and related properties of this family of ionic liquids. A volumetric predictive method based on the effective molar volume of cations and anions is used to estimate the effective molar volume of the different cations present in this study. The results agree with data for other cation families that show a molar volume increment per CH(2) group on the alkyl chain of the cation of about 17.2 cm(3) mol(-1), except for [N(1 1 1 2(OH))](+), which exhibits an outlier behaviour. Molecular dynamics simulation results are used to explain the volumetric behaviour along the homologous series from a molecular perspective. The predictive power of group contribution methods for density and viscosity is also tested. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reducing Contact Resistance Errors In Measuring Thermal ...

African Journals Online (AJOL)

Values of thermal conductivity (k) of glass beads, quartz sand, stone dust and clay were determined using a thermal probe with and without heat sink compounds (arctic silver grease (ASG) and white grease (WG)) at different water contents, bulk densities and particle sizes. The heat sink compounds (HSC) increased k at ...

Cosmic thermalization and the microwave background radiation

International Nuclear Information System (INIS)

Rana, N.C.

1981-01-01

A different origin of the microwave background radiation (MBR) is suggested in view of some of the difficulties associated with the standard interpretation. Extensive stellar-type nucleosynthesis could provide radiation with the requisite energy density of the MBR and its spectral features are guaranteed by adequate thermalization of the above radiation by an ambient intergalactic dust medium. This thermalization must have occurred in quite recent epochs, say around epochs of redshift z = 7. The model emerges with consistent limits on the cosmic abundance of helium, the general luminosity evolution of the extragalactic objects, the baryonic matter density in the Universe (or, equivalently the deceleration parameter) and the degree of isotropy of MBR. The model makes definite predictions on issues like the properties of the intergalactic thermalizers, the degree of isotropy of MBR at submillimetre wavelengths and cluster emission in the far infrared. (author)

Critical phenomena and their effect on thermal energy storage in supercritical fluids

International Nuclear Information System (INIS)

Hobold, Gustavo M.; Da Silva, Alexandre K.

2017-01-01

Highlights: •High power thermal energy storage using supercritical fluids. •Influence of property variation on energy and power density. •Multi-fluid analysis and generalization for several storage temperatures. •Cost, heat transfer and energy density evaluation for high temperature storage. -- Abstract: Large-scale implementation of concentrated solar power plants requires energy storage systems if fossil sources are to be fully replaced. While several candidates have appeared, most still face major issues such as cost, limited energy density and material compatibility. The present paper explores the influence of property variation in the proximity of the critical point on thermal energy storage using supercritical fluids (sTES) from thermodynamic and heat transfer standpoints. Influence of thermodynamic operational parameters on energy density of isobaric and isochoric sTES and their optima is discussed, showing that the energy density results from a competition between average specific heat and loaded density. Moreover, sTES is shown to be applicable to virtually any storage temperature, depending only on the fluid’s critical point. Finally, a heat transfer and energy density comparison to other existing storage mechanisms is presented and supercritical water is shown to be competitive for high temperature thermal energy storage.

Enhancing Low-Grade Thermal Energy Recovery in a Thermally Regenerative Ammonia Battery Using Elevated Temperatures

KAUST Repository

Zhang, Fang

2015-02-13

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA. A thermally regenerative ammonia battery (TRAB) is a new approach for converting low-grade thermal energy into electricity by using an ammonia electrolyte and copper electrodes. TRAB operation at 72°C produced a power density of 236±8 Wm-2, with a linear decrease in power to 95±5 Wm-2 at 23°C. The improved power at higher temperatures was due to reduced electrode overpotentials and more favorable thermodynamics for the anode reaction (copper oxidation). The energy density varied with temperature and discharge rates, with a maximum of 650 Whm-3 at a discharge energy efficiency of 54% and a temperature of 37°C. The energy efficiency calculated with chemical process simulation software indicated a Carnot-based efficiency of up to 13% and an overall thermal energy recovery of 0.5%. It should be possible to substantially improve these energy recoveries through optimization of electrolyte concentrations and by using improved ion-selective membranes and energy recovery systems such as heat exchangers.

Graphite-high density polyethylene laminated composites with high thermal conductivity made by filament winding

Directory of Open Access Journals (Sweden)

W. Lv

2018-03-01

Full Text Available The low thermal conductivity of polymers limits their use in numerous applications, where heat transfer is important. The two primary approaches to overcome this limitation, are to mix in other materials with high thermal conductivity, or mechanically stretch the polymers to increase their intrinsic thermal conductivity. Progress along both of these pathways has been stifled by issues associated with thermal interface resistance and manufacturing scalability respectively. Here, we report a novel polymer composite architecture that is enabled by employing typical composites manufacturing method such as filament winding with the twist that the polymer is in fiber form and the filler in form of sheets. The resulting novel architecture enables accession of the idealized effective medium composite behavior as it minimizes the interfacial resistance. The process results in neat polymer and 50 vol% graphite/polymer plates with thermal conductivity of 42 W·m–1·K–1 (similar to steel and 130 W·m–1·K–1 respectively.

Thermal properties of clay-based buffer materials for a nuclear fuel waste disposal vault

International Nuclear Information System (INIS)

Radhakrishna, H.S.

1984-06-01

The thermal properties of three types of bentonite clay, one illite-rich shale and one kaolin mixed with crushed granite were investigated. Thermal conductivity measurements were made over a range of mix proportions, moisture content, density and ambient temperature using the transient heat-probe method. The effects of thermal drying in the buffer zone prior to water uptake were investigated by means of laboratory-scale heater experiments. Illite-rich shale (Sealbond) and kaolin exhibited better compactability and thermal conductivity than the bentonite clays. The thermal conductivity of all types of clay buffers showed a high degree of moisture dependency and relatively no effect due to elevated temperature under high fluid pressure conditions. Bentonite buffers compacted to a dry density of 1200 to 1400 kg/m 3 showed extensive cracking due to differential shrinkage. Addition of crushed granite, and/or compaction to a higher density, reduced the thermal cracking of the buffer material

Power density effect on feasibility of water cooled thorium breeder reactor

International Nuclear Information System (INIS)

Sidik, Permana; Takaki, Naoyuki; Sekimoto, Hiroshi

2008-01-01

Breeding is made possible by the high value of neutron regeneration ratio η for 233 U in thermal energy region. The reactor is fueled by 233 U-Th oxide and it has used the light water as moderator. Some characteristics such as spectrum, η value, criticality, breeding performance and number density are evaluated. Several power densities are evaluated in order to analyze its effect to the breeding performance. The η value of fissile 233 U obtains higher value than 2 which may satisfy the breeding capability especially for thermal reactor for all investigated MFR. The increasing enrichment and decreasing conversion ratio are more significant for MFR 233 U enrichment. Number density of 233 Pa decreases significantly with decreasing power density which leads the reactor has better breeding performance because lower capture rate of 233 Pa. (author)

Optical Thermal Characterization Enables High-Performance Electronics Applications

Energy Technology Data Exchange (ETDEWEB)

2016-02-01

NREL developed a modeling and experimental strategy to characterize thermal performance of materials. The technique provides critical data on thermal properties with relevance for electronics packaging applications. Thermal contact resistance and bulk thermal conductivity were characterized for new high-performance materials such as thermoplastics, boron-nitride nanosheets, copper nanowires, and atomically bonded layers. The technique is an important tool for developing designs and materials that enable power electronics packaging with small footprint, high power density, and low cost for numerous applications.

Evaluation of risk and benefit in thermal effusivity sensor for monitoring lubrication process in pharmaceutical product manufacturing.

Science.gov (United States)

Uchiyama, Jumpei; Kato, Yoshiteru; Uemoto, Yoshifumi

2014-08-01

In the process design of tablet manufacturing, understanding and control of the lubrication process is important from various viewpoints. A detailed analysis of thermal effusivity data in the lubrication process was conducted in this study. In addition, we evaluated the risk and benefit in the lubrication process by a detailed investigation. It was found that monitoring of thermal effusivity detected mainly the physical change of bulk density, which was changed by dispersal of the lubricant and the coating powder particle by the lubricant. The monitoring of thermal effusivity was almost the monitoring of bulk density, thermal effusivity could have a high correlation with tablet hardness. Moreover, as thermal effusivity sensor could detect not only the change of the conventional bulk density but also the fractional change of thermal conductivity and thermal capacity, two-phase progress of lubrication process could be revealed. However, each contribution of density, thermal conductivity, or heat capacity to thermal effusivity has the risk of fluctuation by formulation. After carefully considering the change factor with the risk to be changed by formulation, thermal effusivity sensor can be a useful tool for monitoring as process analytical technology, estimating tablet hardness and investigating the detailed mechanism of the lubrication process.

Experimental study and numerical modelling of density currents resulting from thermal transients in a non rectilinear pipe flow

International Nuclear Information System (INIS)

Viollet, P.L.

1985-01-01

The present study found its motivation in the application to sodium secondary bond of Fast Reactors. The field of application of the methods proposed in this report is larger and can include, by example, the study of some fluid flows in pipes of water cooled reactors. In a U-shaped pipe (the water experiment STRATUS), are studied the density effects following a change in the inlet temperature. Stratus reproduces at the scale 1/4 the geometry of the U situated at the Super Phenix Steam generator outlet. When the flow rate is small and the temperature difference high, thermal stratifications appear. The two-dimensional numerical modelling (computer code ULYSSE) uses finite difference methods with a curvilinear grid, and k-epsilon models for turbulence. The computation allows to predict with good accuracy the phenomena which are observed from experiment [fr

Measurements of density and of thermal expansion coefficient of sodium tetraborate (borax)-UO2 and of sodium metaborate-UO2 solutions

International Nuclear Information System (INIS)

Dalle Donne, M.; Dorner, S.

1980-12-01

Measurements have been performed of the density and volumetric thermal expansion coefficient of liquid sodium tetraborate (borax) and of sodium metaborate both pure and with two different amounts of UO 2 dissolved in each. These data are required for the design of core-catchers based on sodium borates. The measurements have been performed with the buoyancy method in the temperature range from 850 0 C to 1325 0 C. The data for the pure borax and for the sodium metaborate agree reasonably well with the data from the literature, giving confidence that the measurements are correct and the new data for the salts with UO 2 are reliable. (orig.) [de

Thermal interactions of the AD79 Vesuvius pyroclastic density currents and their deposits at Villa dei Papiri (Herculaneum archaeological site, Italy)

Science.gov (United States)

Giordano, G.; Zanella, E.; Trolese, M.; Baffioni, C.; Vona, A.; Caricchi, C.; De Benedetti, A. A.; Corrado, S.; Romano, C.; Sulpizio, R.; Geshi, N.

2018-05-01

Pyroclastic density currents (PDCs) can have devastating impacts on urban settlements, due to their dynamic pressure and high temperatures. Our degree of understanding of the interplay between these hot currents and the affected infrastructures is thus fundamental not only to implement our strategies for risk reduction, but also to better understand PDC dynamics. We studied the temperature of emplacement of PDC deposits that destroyed and buried the Villa dei Papiri, an aristocratic Roman edifice located just outside the Herculaneum city, during the AD79 plinian eruption of Mt Vesuvius (Italy) by using the thermal remanent magnetization of embedded lithic clasts. The PDC deposits around and inside the Villa show substantial internal thermal disequilibrium. In areas affected by convective mixing with surface water or with collapsed walls, temperatures average at around 270 °C (min 190 °C, max 300 °C). Where the deposits show no evidence of mixing with external material, the temperature is much higher, averaging at 350 °C (min 300 °C; max 440 °C). Numerical simulations and comparison with temperatures retrieved at the very same sites from the reflectance of charcoal fragments indicate that such thermal disequilibrium can be maintained inside the PDC deposit for time-scales well over 24 hours, i.e. the acquisition time of deposit temperatures for common proxies. We reconstructed in detail the history of the progressive destruction and burial of Villa dei Papiri and infer that the rather homogeneous highest deposit temperatures (average 350 °C) were carried by the ash-sized fraction in thermal equilibrium with the fluid phase of the incoming PDCs. These temperatures can be lowered on short time- (less than hours) and length-scales (meters to tens of meters) only where convective mixing with external materials or fluids occurs. By contrast, where the Villa walls remained standing the thermal exchange was only conductive and very slow, i.e. negligible at 50 cm

Thermal Properties of Algerian Diatomite, Study of the Possibility to Its Use in the Thermal Insulation

Science.gov (United States)

Hamdi, Boualem; Hamdi, Safia

The chemical and physical properties of a Algerian diatomite were given before and after heat treatment and chemical with an aim of a use in the heat insulation of constructions. The preliminary results obtained showed that this material is extremely porous (porosity >70 %), characterized of a low density and a very low thermal conductivity. These promising properties support the use of this local material in the thermal insulation.

Identifying WIMP dark matter from particle and astroparticle data

Science.gov (United States)

Bertone, Gianfranco; Bozorgnia, Nassim; Kim, Jong Soo; Liem, Sebastian; McCabe, Christopher; Otten, Sydney; Ruiz de Austri, Roberto

2018-03-01

One of the most promising strategies to identify the nature of dark matter consists in the search for new particles at accelerators and with so-called direct detection experiments. Working within the framework of simplified models, and making use of machine learning tools to speed up statistical inference, we address the question of what we can learn about dark matter from a detection at the LHC and a forthcoming direct detection experiment. We show that with a combination of accelerator and direct detection data, it is possible to identify newly discovered particles as dark matter, by reconstructing their relic density assuming they are weakly interacting massive particles (WIMPs) thermally produced in the early Universe, and demonstrating that it is consistent with the measured dark matter abundance. An inconsistency between these two quantities would instead point either towards additional physics in the dark sector, or towards a non-standard cosmology, with a thermal history substantially different from that of the standard cosmological model.

Z2 SIMP dark matter

International Nuclear Information System (INIS)

Bernal, Nicolás; Chu, Xiaoyong

2016-01-01

Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a Z 2 symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model

Electroweak baryogenesis, large Yukawas and dark matter

International Nuclear Information System (INIS)

Provenza, Alessio; Quiros, Mariano; Ullio, Piero

2005-01-01

It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show here that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upcoming experiments. We find, contrary to the standard lore, that indirect detection searches are more promising than direct ones, and they already exclude part of the parameter space

Dark Matter candidates in a baryogenesis inspired scenario

International Nuclear Information System (INIS)

Provenza, A; Quiros, M; Ullio, P

2006-01-01

It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upcoming experiments. We find, contrary to the standard lore, that indirect detection searches are more promising than direct ones, and they already exclude part of the parameter space

A transient divided-bar method for simultaneous measurements of thermal conductivity and thermal diffusivity

DEFF Research Database (Denmark)

Bording, Thue Sylvester; Nielsen, Søren Bom; Balling, Niels

2016-01-01

and volumetric heat capacity, and thereby also thermal diffusivity, are measured simultaneously. As the density of samples is easily determined independently, specific heat capacity may also be determined. Finite element formulation provides a flexible forward solution for heat transfer across the bar...... and thermal properties are estimated by inverse Monte Carlo modelling. This methodology enables a proper quantification of experimental uncertainties on measured thermal properties. The developed methodology was applied to laboratory measurements of various materials, including a standard ceramic material......-3 %, and for diffusivity uncertainty may be reduced to about 3-5 %. The main uncertainty originates from the presence of thermal contact resistance associated with the internal interfaces of the bar. They are not resolved during inversion, and it is highly important that they are minimized by careful sample preparation....

Thermal conductivity of partially graphitized biocarbon obtained by carbonization of medium-density fiberboard in the presence of a Ni-based catalyst

Science.gov (United States)

Orlova, T. S.; Parfen'eva, L. S.; Smirnov, B. I.; Gutierrez-Pardo, A.; Ramirez-Rico, J.

2016-01-01

The thermal conductivity k and resistivity ρ of biocarbon matrices, prepared by carbonizing medium-density fiberboard at T carb = 850 and 1500°C in the presence of a Ni-based catalyst (samples MDF-C( Ni)) and without a catalyst (samples MDF-C), have been measured for the first time in the temperature range of 5-300 K. X-ray diffraction analysis has revealed that the bulk graphite phase arises only at T carb = 1500°C. It has been shown that the temperature dependences of the thermal conductivity of samples MDFC- 850 and MDF-C-850(Ni) in the range of 80-300 K are to each other and follow the law of k( T) ˜ T 1.65, but the use of the Ni-catalyst leads to an increase in the thermal conductivity by a factor of approximately 1.5, due to the formation of a greater fraction of the nanocrystalline phase in the presence of the Ni-catalyst at T carb = 850°C. In biocarbon MDF-C-1500 prepared without a catalyst, the dependence is k( T) ˜ T 1.65, and it is controlled by the nanocrystalline phase. In MDF-C-1500(Ni), the bulk graphite phase formed increases the thermal conductivity by a factor of 1.5-2 compared to the thermal conductivity of MDF-C-1500 in the entire temperature range of 5-300 K; k( T = 300 K) reaches the values of ˜10 W m-1 K-1, characteristic of biocarbon obtained without a catalyst only at high temperatures of T carb = 2400°C. It has been shown that MDF-C-1500(Ni) in the temperature range of 40‒300 K is characterized by the dependence, k( T) ˜ T 1.3, which can be described in terms of the model of partially graphitized biocarbon as a composite of an amorphous matrix with spherical inclusions of the graphite phase.

Mechanical, Morphological, and Thermal Properties of Nutshell and Microcrystalline Cellulose Filled High-Density Polyethylene Composites

Directory of Open Access Journals (Sweden)

Sevda Boran

2016-01-01

Full Text Available Effects of nutshell fiber loadings of 30 wt.% and MCC loadings up to 15 wt.% on some properties of high-density polyethylene composites (HDPE were investigated. The composites were manufactured by a single screw extruder and injection molding. The experimental composite samples were tested for their mechanical performance including tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength. Thermal and morphological properties of the composites were tested by differential scanning calorimetry-DSC and scanning electron microscopy (SEM, respectively. The maximum tensile strength was obtained from the MCC-filled composites, whereas the maximum flexural strength was achieved with the MCC-nutshell filled composites. The tensile and flexural moduli of the composites were significantly improved with increasing MCC content and the presence of nutshell fibers in polymer matrix. Impact strength decreased using MCC and nutshell fiber in the polymer matrix. Based on the DSC results, there was no remarkable change in the melting point for all composites. The results showed that the incorporation of nutshell fibers and MCC in the polymer matrix had brought about some positive effect on mechanical properties of HDPE composites.

The influence of expanded graphite on thermal properties for paraffin/high density polyethylene/chlorinated paraffin/antimony trioxide as a flame retardant phase change material

International Nuclear Information System (INIS)

Zhang Ping; Song Lei; Lu Hongdian; Wang Jian; Hu Yuan

2010-01-01

The influences of expanded graphite (EG) on the thermal properties of chlorinated paraffin (CP) and antimony trioxide (AT) on phase change material which bases on paraffin/high density polyethylene (HDPE) are studied. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermogravimetric analysis-Fourier transform infrared spectrometry (TGA-FTIR), microscale combustion calorimeter (MCC) and cone calorimeter (CONE) were used to evaluate the influence of EG on paraffin/HDPE/CP/AT system. The DSC results indicated that the latent heat value of PCM could be increased when the mass fraction of HDPE was decreased in the PCM, and EG could confine the molecular heat movement of paraffin. EG could improve the thermal stability and increase the char residue at high temperature for paraffin/HDPE/CP/AT hybrid. The volatilized products formed on thermal degradation of paraffin/HDPE/CP/AT with EG showed the release of CO 2 gas was hastened and increased, and the amount of combustible gases were decreased by TGA-FTIR analysis. The MCC and CONE results presented that the flame retardant efficiency of CP/AT could be improved by adding EG in paraffin/HDPE/CP/AT system.

Heat and density pulse propagation in ASDEX

International Nuclear Information System (INIS)

Giannone, L.; Riedel, K.; Stroth, U.; Eberhagen, A.; Gruber, O.; Mertens, V.

1990-01-01

Experimental measurements of the electron thermal conductivity, derived from the radial propagation of the heat pulse generated by a sawtooth crash, have consistently yielded larger values than those obtained by power balance. It has been proposed that this discrepancy could be the result of the coupling of density and temperature perturbations. Numerical modelling of heat and density pulse propagation on ASDEX has been used to address this question. In addition, measurements at various electron densities and in hydrogen and deuterium were undertaken, with the aim of providing a broad base of experimental measurements for testing the various transport models proposed. (orig.)

Thermal properties at Aespoe HRL. Analysis of distribution and scale factors

International Nuclear Information System (INIS)

Sundberg, Jan

2003-04-01

A thermal model for the Aespoe HRL as well as a general strategy for thermal modelling is under development. As a part of that work, thermal conductivities have been modelled from reference values of thermal conductivity of different minerals and from the mineral composition of all Aespoe samples in the Sicada database. The produced thermal conductivity database has been analysed in terms of frequency, type of distribution, spatial distribution, variogram etc. A correction factor has been estimated to compensate for discrepancies between measured and calculated values. The calculated values have been corrected according to measured values. The data has been analysed according to different rock types. However, there are uncertainties in the base material of rock classification, mainly due to problem to distinguish between Aespoe diorite and Aevroe granite, but also because of different classification systems. There is a relationship between thermal conductivity and density for the rock types at Aespoe. Equations of the relationship have been developed based on all thermal conductivity, heat capacity and density measurements. The equations have been tested on two bore holes at Aespoe with promising results. It may be possible to evaluate the spatial distribution of the thermal properties from density loggings. However, more work is needed to develop a complete model including the handling of high and low density zones. There is an insufficient knowledge in the variation of thermal properties at different scales. If the whole variation within a rock type is in the cm-m scale the thermal influence on the canister is small. This is due to the fact that the small-scale variation in thermal properties is mainly averaged out in the 5-10 m scale. If the main variation within rock types is in the 5-10 m scale there is probably a significant effect on the canister temperature. However, it is likely that the observed variation occurs in both these scales. Simulation has been

Fluctuations in the thermal superfluid model for heated spherical nuclei

International Nuclear Information System (INIS)

Nguyen Dinhdang; Nguyen Zuythang

1990-01-01

The effect of the non-vanishing thermal pairing gap due to statistical fluctuations is investigated by calculating fluctuations of selected observables such as the energy and particle number fluctuations, the nuclear level density, the level density parameter and the specific heat within the framework of the thermal nuclear superfluid model. In numerical calculations for heated spherical nuclei 58 Ni, 142 Sm and 208 Pb the realistic single-particle energy spectra defined in the Woods-Saxon potential are used. It is found that the results obtained with the non-vanishing thermal average pairing gap can yield an adequate estimate of the true fluctuations in the finite heating non-rotating nuclear systems. (author)

Solar-thermal conversion and thermal energy storage of graphene foam-based composite

KAUST Repository

Zhang, Lianbin

2016-07-11

Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

Science.gov (United States)

Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

2016-08-14

Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

Prediction of thermal conductivity of sedimentary rocks from well logs

DEFF Research Database (Denmark)

Fuchs, Sven; Förster, Andrea

2014-01-01

The calculation of heat-flow density in boreholes requires reliable values for the change of temperature and rock thermal conductivity with depth. As rock samples for laboratory measurements of thermal conductivity (TC) are usually rare geophysical well logs are used alternatively to determine TC...... parameters (i.e. thermal conductivity, density, hydrogen index, sonic interval transit time, gamma-ray response, photoelectric factor) of artificial mineral assemblages consisting 15 rock-forming minerals that are used in different combinations to typify sedimentary rocks. The predictive capacity of the new...... equations is evaluated on subsurface data from four boreholes drilled into the Mesozoic sequence of the North German Basin, including more than 1700 laboratory-measured thermal-conductivity values. Results are compared with those from other approaches published in the past. The new approach predicts TC...