WorldWideScience

Sample records for surface thermal radiation

  1. Thermal radiation from magnetic neutron star surfaces

    CERN Document Server

    Pérez-Azorin, J F; Pons, J A

    2005-01-01

    We investigate the thermal emission from magnetic neutron star surfaces in which the cohesive effects of the magnetic field have produced the condensation of the atmosphere and the external layers. This may happen for sufficiently cool atmospheres with moderately intense magnetic fields. The thermal emission from an isothermal bare surface of a neutron star shows no remarkable spectral features, but it is significantly depressed at energies below some threshold energy. However, since the thermal conductivity is very different in the normal and parallel directions to the magnetic field lines, the presence of the magnetic field is expected to produce a highly anisotropic temperature distribution, depending on the magnetic field geometry. In this case, the observed flux of such an object looks very similar to a BB spectrum, but depressed in a nearly constant factor at all energies. This results in a systematic underestimation of the area of the emitter (and therefore its size) by a factor 5-10 (2-3).

  2. Variable Surface Area Thermal Radiator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Due to increased complexity of spacecraft and longer expected life, more sophisticated and complex thermal management schemes are needed that will be capable of...

  3. Thermal radiation heat transfer

    CERN Document Server

    Howell, John R; Siegel, Robert

    2016-01-01

    Further expanding on the changes made to the fifth edition, Thermal Radiation Heat Transfer, 6th Edition continues to highlight the relevance of thermal radiative transfer and focus on concepts that develop the radiative transfer equation (RTE). The book explains the fundamentals of radiative transfer, introduces the energy and radiative transfer equations, covers a variety of approaches used to gauge radiative heat exchange between different surfaces and structures, and provides solution techniques for solving the RTE.

  4. Effect of Joule heating and thermal radiation in flow of third grade fluid over radiative surface.

    Science.gov (United States)

    Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

    2014-01-01

    This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number.

  5. Effect of Joule heating and thermal radiation in flow of third grade fluid over radiative surface.

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    Full Text Available This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number.

  6. Thermal radiation heat transfer

    CERN Document Server

    Howell, John R; Mengüç, M Pinar

    2011-01-01

    Providing a comprehensive overview of the radiative behavior and properties of materials, the fifth edition of this classic textbook describes the physics of radiative heat transfer, development of relevant analysis methods, and associated mathematical and numerical techniques. Retaining the salient features and fundamental coverage that have made it popular, Thermal Radiation Heat Transfer, Fifth Edition has been carefully streamlined to omit superfluous material, yet enhanced to update information with extensive references. Includes four new chapters on Inverse Methods, Electromagnetic Theory, Scattering and Absorption by Particles, and Near-Field Radiative Transfer Keeping pace with significant developments, this book begins by addressing the radiative properties of blackbody and opaque materials, and how they are predicted using electromagnetic theory and obtained through measurements. It discusses radiative exchange in enclosures without any radiating medium between the surfaces-and where heat conduction...

  7. An experiment to distinguish between diffusive and specular surfaces for thermal radiation in cryogenic gravitational-wave detectors

    Science.gov (United States)

    Sakakibara, Yusuke; Kimura, Nobuhiro; Suzuki, Toshikazu; Yamamoto, Kazuhiro; Tokoku, Chihiro; Uchiyama, Takashi; Kuroda, Kazuaki

    2015-07-01

    In cryogenic gravitational-wave detectors, one of the most important issues is the fast cooling of their mirrors and keeping them cool during operation to reduce thermal noise. For this purpose, the correct estimation of thermal-radiation heat transfer through the pipe-shaped radiation shield is vital to reduce the heat load on the mirrors. However, the amount of radiation heat transfer strongly depends on whether the surfaces reflect radiation rays diffusely or specularly. Here, we propose an original experiment to distinguish between diffusive and specular surfaces. This experiment has clearly shown that the examined diamond-like carbon-coated surface is specular. This result emphasizes the importance of suppressing the specular reflection of radiation in the pipe-shaped shield.

  8. Near-field thermal radiative emission of materials demonstrating near infrared surface polariton resonance

    Science.gov (United States)

    Petersen, Spencer Justin

    Surface polariton mediated near-field radiative transfer exceeds the blackbody limit by orders of magnitude and is quasimonochromatic. Thermophotovoltaic (TPV) power generation consists of converting thermal radiation into useful electrical energy and exhibits a peak performance near the TPV cell bandgap, which is typically located within the near infrared bandwidth. Therefore, an ideal emission source for a nanoscale gap TPV device, in which the emitter and cell are separated by no more than one peak emitted wavelength, will sustain surface polariton resonance at or near the TPV cell bandgap in the near infrared. To date, few materials have been identified that satisfy this requirement. The first objective of this dissertation is to theoretically explore dielectric Mie resonance-based (DMRB) electromagnetic metamaterials for the potential to sustain near infrared surface polariton resonance. Electromagnetic metamaterials are composite media, consisting of subwavelength, repeating unit structures called "meta-atoms." The microscopic configuration of the meta-atom can be engineered, dictating the effective macroscale electromagnetic properties of the bulk metamaterial, including the surface polariton resonance wavelength. DMRB metamaterials consist of dielectric nanoparticles within a host medium and are analyzed using an effective medium theory. The local density of electromagnetic states, an indicator of possibly harvestable energy near an emitting surface, is calculated for two DMRB metamaterials: spherical nanoparticles of 1) silicon carbide, and 2) silicon embedded in a host medium. Results show that the surface polariton resonance of these metamaterials is tunable and, for the silicon metamaterial only, is found in the near infrared bandwidth, making it a viable candidate for use in a nano-TPV device. In order to demonstrate the practicality thereof, the second objective is to fabricate and characterize DMRB metamaterials. Specimens are fabricated by hand

  9. Sensitivity analysis of radiative transfer for atmospheric remote sensing in thermal IR: atmospheric weighting functions and surface partials

    Science.gov (United States)

    Ustinov, E. A.

    2003-01-01

    In this presentation, we apply the adjoint sensitivity analysis of radiative transfer in thermal IR to the general case of the analytic evaluation of the weighting functions of atmospheric parameters together with the partial derivatives for the surface parameters. Applications to remote sensing of atmospheres of Mars and Venus are discussed.

  10. Casson fluid flow and heat transfer past an exponentially porous stretching surface in presence of thermal radiation

    Directory of Open Access Journals (Sweden)

    S. Pramanik

    2014-03-01

    Full Text Available The present paper aims at investigating the boundary layer flow of a non-Newtonian fluid accompanied by heat transfer toward an exponentially stretching surface in presence of suction or blowing at the surface. Casson fluid model is used to characterize the non-Newtonian fluid behavior. Thermal radiation term is incorporated into the equation for the temperature field. With the help of similarity transformations, the governing partial differential equations corresponding to the momentum and heat transfer are reduced to a set of non-linear ordinary differential equations. Numerical solutions of these equations are then obtained. The effect of increasing values of the Casson parameter is seen to suppress the velocity field. But the temperature is enhanced with increasing Casson parameter. Thermal radiation enhances the effective thermal diffusivity and the temperature increases. It is found that the skin-friction coefficient increases with the increase in suction parameter.

  11. Lecture on Thermal Radiation

    Science.gov (United States)

    Dennis, Brian R.

    2006-01-01

    This lecture will cover solar thermal radiation, particularly as it relates to the high energy solar processes that are the subject of this summer school. After a general review of thermal radiation from the Sun and a discussion of basic definitions, the various emission and absorption mechanisms will be described including black-body emission, bremsstrahlung, free-bound, and atomic line emissions of all kinds. The bulk of the time will be spent discussing the observational characteristics of thermal flare plasma and what can be learned about the flare energy release process from observations of the thermal radiation at all wavelengths. Information that has been learned about the morphology, temperature distribution, and composition of the flare plasma will be presented. The energetics of the thermal flare plasma will be discussed in relation to the nonthermal energy of the particles accelerated during the flare. This includes the total energy, the radiated and conductive cooling processes, and the total irradiated energy.

  12. Magnetohydrodynamic flow of a Casson fluid over an exponentially inclined permeable stretching surface with thermal radiation and chemical reaction

    Directory of Open Access Journals (Sweden)

    P. Bala Anki Reddy

    2016-06-01

    Full Text Available This article investigates the theoretical study of the steady two-dimensional MHD convective boundary layer flow of a Casson fluid over an exponentially inclined permeable stretching surface in the presence of thermal radiation and chemical reaction. The stretching velocity, wall temperature and wall concentration are assumed to vary according to specific exponential form. Velocity slip, thermal slip, solutal slip, thermal radiation, chemical reaction and suction/blowing are taken into account. The proposed model considers both assisting and opposing buoyant flows. The non-linear partial differential equations of the governing flow are converted into a system of coupled non-linear ordinary differential equations by using the similarity transformations, which are then solved numerically by shooting method with fourth order Runge–Kutta scheme. The numerical solutions for pertinent parameters on the dimensionless velocity, temperature, concentration, skin friction coefficient, the heat transfer coefficient and the Sherwood number are illustrated in tabular form and are discussed graphically.

  13. Paradoxes of Thermal Radiation

    Science.gov (United States)

    Besson, U.

    2009-01-01

    This paper presents an analysis of the thermal behaviour of objects exposed to a solar-type flux of thermal radiation. It aims to clarify certain apparent inconsistencies between theory and observation, and to give a detailed exposition of some critical points that physics textbooks usually treat in an insufficient or incorrect way. In particular,…

  14. Paradoxes of Thermal Radiation

    Science.gov (United States)

    Besson, U.

    2009-01-01

    This paper presents an analysis of the thermal behaviour of objects exposed to a solar-type flux of thermal radiation. It aims to clarify certain apparent inconsistencies between theory and observation, and to give a detailed exposition of some critical points that physics textbooks usually treat in an insufficient or incorrect way. In particular,…

  15. Thermophoresis and Brownian effects on the Blasius flow of a nanofluid due to a curved surface with thermal radiation

    Science.gov (United States)

    Naveed, M.; Abbas, Z.; Sajid, M.

    2016-06-01

    In this analysis, we have discussed the Blasius flow of a nanofluid over a curved surface coiled in a circle of radius R . The physical situation is formulated in a mathematical model using a curvilinear coordinates system. The model is considered for the nanofluid including the effects of Brownian motion and thermophoresis in the presence of thermal radiation. A similarity solution of the developed ordinary differential equations is obtained numerically using the shooting method. The influence of the various involved parameters on the flow phenomena are analyzed through graphs and tables.

  16. Viscous Dissipation and Thermal Radiation effects in MHD flow of Jeffrey Nanofluid through Impermeable Surface with Heat Generation/Absorption

    Science.gov (United States)

    Sharma, Kalpna; Gupta, Sumit

    2017-06-01

    This paper investigates steady two dimensional flow of an incompressible magnetohydrodynamic (MHD) boundary layer flow and heat transfer of nanofluid over an impermeable surface in presence of thermal radiation and viscous dissipation. By using similarity transformation, the arising governing equations of momentum, energy and nanoparticle concentration are transformed into coupled nonlinear ordinary differential equations, which are than solved by homotopy analysis method (HAM). The effect of different physical parameters, namely, Prandtl number Pr, Eckert number Ec, Magnetic parameter M, Brownian motion parameter Nb, Thermophoresis parameter Nt, Lewis parameter Le and Radiation parameter Rd on the velocity, temperature and concentration profiles along with the Nusselt number and skin friction coefficient are discussed graphically and in tabular form in details. The present results are also compared with existing limiting solutions.

  17. Pulsar Polar Cap Heating and Surface Thermal X-Ray Emission I. Curvature Radiation Pair Fronts

    CERN Document Server

    Harding, A K; Harding, Alice K.; Muslimov, Alexander G.

    2001-01-01

    We investigate the effect of pulsar polar cap (PC) heating produced by positrons returning from the upper pair formation front. Our calculations are based on a self-consistent treatment of the pair dynamics and the effect of electric field screening by the returning positrons. We calculate the resultant X-ray luminosities, and discuss the dependence of the PC heating efficiencies on pulsar parameters, such as characteristic spin-down age, spin period, and surface magnetic field strength. In this study we concentrate on the regime where the pairs are produced in a magnetic field by curvature photons emitted by accelerating electrons. Our theoretical results are not in conflict with the available observational X-ray data and suggest that the effect of PC heating should significantly contribute to the thermal X-ray fluxes from middle-aged and old pulsars. The implications for current and future X-ray observations of pulsars are briefly outlined.

  18. Evaluation of Arctic broadband surface radiation measurements

    OpenAIRE

    N. Matsui; C. N. Long; Augustine, J.; D. Halliwell; T. Uttal; Longenecker, D.; Niebergall, O.; Wendell, J.; Albee, R.

    2012-01-01

    The Arctic is a challenging environment for making in-situ surface radiation measurements. A standard suite of radiation sensors is typically designed to measure incoming and outgoing shortwave (SW) and thermal infrared, or longwave (LW), radiation. Enhancements may include various sensors for measuring irradiance in narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers) that ...

  19. Thermal Radiation Source Test Facility,

    Science.gov (United States)

    1984-01-01

    KEY WORDS (Continu on revers side I eesr and identify by block nuMb.,) Thermal Radiation Source Thermal Test Facility 20 ABSTRACT (Continue on reverse...SECTION 1 INTRODUCTION 1-1 GENERAL Defense Nuclear Agency’s Field Command, located at Kirtland AFB in New Mexico, has recently upgraded its thermal test facility...is used to evaluate damage and survivability in a nuclear environment. The thermal test facility was first established in 1979 and used O large

  20. Effects of Variable Thermal Conductivity with Thermal Radiation on MHD Flow and Heat Transfer of Casson Liquid Film Over an Unsteady Stretching Surface

    Science.gov (United States)

    El-Aziz, Mohamed Abd; Afify, Ahmed A.

    2016-10-01

    In the present work, the hydromagnetic boundary layer flow and heat transfer of Casson fluid in a thin liquid film over an unsteady stretching sheet in the presence of variable thermal conductivity, thermal radiation, and viscous dissipation is investigated numerically. The Casson fluid model is applied to characterize the non-Newtonian fluid behavior. Similarity equations are derived and then solved numerically by using a shooting method with fourth order Runge-Kutta integration scheme. Comparisons with previous literature are accomplished and obtained an excellent agreement. The influences of parameters governing a thin liquid film of Casson fluid and heat transfer characteristics are presented graphically and analyzed. It is observed that the heat transfer rate diminishes with a rise in thermal conductivity parameter and Eckert number. Further, the opposite influence is found with an increase in radiation parameter.

  1. Influence of Absorption of Thermal Radiation in the Surface Water Film on the Characteristics and Ignition Conditions

    Directory of Open Access Journals (Sweden)

    Syrodoy Samen V.

    2016-01-01

    Full Text Available The results of the mathematical modeling of homogeneous particle ignition process of coal-water fuel covered with water film have been presented in article. The set co-occurring physical (inert heating, evaporation of water film and thermochemical (thermal degradation, inflammation process have been considered. Heat inside the film has been considered as the model of radiation-conductive heat transfer. Delay times have been determined according to the results of numerical modeling of the ignition. It has been shown that the water film can have a significant impact on performance and the ignition conditions. It has been found that heating main fuel layer occurs in the process of evaporation of water film. For this reason, the next (after the evaporation of the water film thermal preparation (coal heating, thermal decomposition of the organic part of the fuel and inflammation occur faster.

  2. Thermal evolution of the Kramer radiating star

    Indian Academy of Sciences (India)

    M Govender; S D Maharaj; L Mkhize; D B Lortan

    2016-01-01

    The Kramer radiating star uses the interior Schwarzschild solution as a seed solution to generate a model of dissipative collapse. We investigate the thermal behaviour of the radiating star by employing a causal heat transport equation. The causal temperature is explicitly determined for the first time by integrating the transport equation. We further show that the dissipation of energy to the exterior space-time renders the core more unstable than the cooler surface layers.

  3. Simulation of Sentinel-3 images by four stream surface atmosphere radiative transfer modeling in the optical and thermal domains

    NARCIS (Netherlands)

    Verhoef, W.; Bach, H.

    2012-01-01

    Simulation of future satellite images can be applied in order to validate the general mission concept and to test the performance of advanced multi-sensor algorithms for the retrieval of surface parameters. This paper describes the radiative transfer modeling part of a so-called Land Scene Generator

  4. Simulation of Sentinel-3 images by four stream surface atmosphere radiative transfer modeling in the optical and thermal domains

    NARCIS (Netherlands)

    Verhoef, W.; Bach, H.

    2012-01-01

    Simulation of future satellite images can be applied in order to validate the general mission concept and to test the performance of advanced multi-sensor algorithms for the retrieval of surface parameters. This paper describes the radiative transfer modeling part of a so-called Land Scene Generator

  5. MHD Mixed Convection Oscillatory Flow over a Vertical Surface in a Porous Medium with Chemical Reaction and Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Venkata Ramana Reddy Gurramapti

    2016-01-01

    Full Text Available The present paper concerns with the study of thermal radiation and magnetohydrodynamic effects on mixed convection flow of a viscous incompressible electrically-conducting fluid through a porous medium with variable permeability in the presence of oscillatory suction. The influence of a first-order homogeneous chemical reaction, heat source and Soret effects are analyzed. The resultant governing boundary layer equations are highly nonlinear and coupled form of partial differential equations which are solved analytically using two-term harmonic and non-harmonic functions. The effects of different physical parameters on the velocity, temperature and concentration fields are discussed in detail. The results are presented graphically and discussed qualitatively.

  6. Thermal radiation of conducting nanoparticles

    CERN Document Server

    Martynenko, Y V; Martynenko, Yu. V.

    2005-01-01

    A simple and universal criterion was obtained for the thermal radiation energy loss efficiency by small conductive particles which include along with metals and graphite also most practically important metal carbides like tungsten carbide, titanium carbide and the number of others.

  7. Group Theoretical Analysis of non-Newtonian Fluid Flow, Heat and Mass Transfer over a Stretching Surface in the Presence of Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Muhammad Tufail

    2016-01-01

    Full Text Available The present article examines the flow, heat and mass transfer of a non-Newtonian fluid known as Casson fluid over a stretching surface in the presence of thermal radiations effects. Lie Group analysis is used to reduce the governing partial differential equations into non-linear ordinary differential equations. These equations are then solved by an analytical technique known as Homotopy Analysis Method (HAM. A comprehensive study of the problem is being made for various parameters involving in the equations through tables and graphs.

  8. Thermal effects in radiation processing

    Energy Technology Data Exchange (ETDEWEB)

    Zagorski, Z.P.

    1984-10-21

    The balance of ionizing radiation energy incident on an object being processed is discussed in terms of energy losses, influencing the amount really absorbed. To obtain the amount of heat produced, the absorbed energy is corrected for the change in internal energy of the system and for the heat effect of secondary reactions developing after the initiation. The temperature of a processed object results from the heat evolved and from the specific heat of the material comprising the object. The specific heat of most materials is usually much lower than that of aqueous systems and therefore temperatures after irradiation are higher. The role of low specific heat in radiation processing at cryogenic conditions is stressed. Adiabatic conditions of accelerator irradiation are contrasted with the steady state thermal conditions prevailing in large gamma sources. Among specific questions discussed in the last part of the paper are: intermediate and final temperature of composite materials, measurement of real thermal effects in situ, neutralization of undesired warming experienced during radiation processing, processing at temperatures other than ambient and administration of very high doses of radiation.

  9. Effects of Thermal Radiation on Mixed Convection Flow of a Micropolar Fluid from an Unsteady Stretching Surface with Viscous Dissipation and Heat Generation/Absorption

    Directory of Open Access Journals (Sweden)

    Khilap Singh

    2016-01-01

    Full Text Available A numerical model is developed to examine the effects of thermal radiation on unsteady mixed convection flow of a viscous dissipating incompressible micropolar fluid adjacent to a heated vertical stretching surface in the presence of the buoyancy force and heat generation/absorption. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The model contains nonlinear coupled partial differential equations which have been converted into ordinary differential equation by using the similarity transformations. The dimensionless governing equations for this investigation are solved by Runge-Kutta-Fehlberg fourth fifth-order method with shooting technique. Numerical solutions are then obtained and investigated in detail for different interesting parameters such as the local skin-friction coefficient, wall couple stress, and Nusselt number as well as other parametric values such as the velocity, angular velocity, and temperature.

  10. Effects of thermal radiation and heat transfer over an unsteady stretching surface embedded in a porous medium in the presence of heat source or sink

    Directory of Open Access Journals (Sweden)

    Elsayed M. A Elbashbeshy

    2011-01-01

    Full Text Available The effects of thermal radiation and heat transfer over an unsteady stretching surface embedded in a porous medium in the presence of heat source or sink are studied. The governing time dependent boundary layer equations are transformed to ordinary differential equations containing radiation parameter, permeability parameter, heat source or sink parameter, Prandtl number, and unsteadiness parameter. These equations are solved numerically by applying Nachtsheim-Swinger shooting iteration technique together with Rung-Kutta fourth order integration scheme. The velocity profiles, temperature profiles, the skin friction coefficient, and the rate of heat transfer are computed and discussed in details for various values of the different parameters. Comparison of the obtained numerical results is made with previously published results.

  11. Pulsar Polar Cap Heating and Surface Thermal X-Ray Emission. II. Inverse Compton Radiation Pair Fronts

    CERN Document Server

    Muslimov, A G; Muslimov, Alice K. Harding & Alexander

    2002-01-01

    We investigate the production of electron-positron pairs by inverse Compton scattered (ICS) photons above a pulsar polar cap (PC) and surface heating by returning positrons. This paper is a continuation of our self-consistent treatment of acceleration, pair dynamics and electric field screening above pulsar PCs. We calculate the altitude of the inverse Compton pair formation fronts, the flux of returning positrons and present the heating efficiencies and X-ray luminosities. We revise pulsar death lines implying cessation of pair formation, and present them in surface magnetic field-period space. We find that virtually all known radio pulsars are capable of producing pairs by resonant and non-resonant ICS photons radiated by particles accelerated above the PC in a pure star-centered dipole field, so that our ICS pair death line coincides with empirical radio pulsar death. Our calculations show that ICS pairs are able to screen the accelerating electric field only for high neutron star surface temperatures and ...

  12. Magnetohydrodynamic and thermal radiation effects on the boundary-layer flow due to a moving extensible surface with the velocity slip model: A comparative study of four nanofluids

    Science.gov (United States)

    Aly, Emad H.; Sayed, Hamed M.

    2017-01-01

    In the current work, we investigated effects of the velocity slip for the flow and heat transfer of four nanofluids over a non-linear stretching sheet taking into account the thermal radiation and magnetic field in presence of the effective electrical conductivity. The governing partial differential equations were transformed into a set of nonlinear ordinary differential equation using similarity transformations before being solved numerically by the Chebyshev pseudospectral differentiation matrix (ChPDM). It was found that the investigated parameters affect remarkably on the nanofluid stream function for the whole investigated nanoparticles. In addition, velocity and skin friction profiles of the four investigated nanofluids decreases and increases, respectively, with the increase of the magnetic parameter, first-order and second-order velocity slips. Further, the flow velocity, surface shear stress and temperature are strongly influenced on applying the velocity slip model, where lower values of the second-order imply higher surface heat flux and thereby making the fluid warmer.

  13. The effects of solar radiation and black body re-radiation on thermal comfort.

    Science.gov (United States)

    Hodder, Simon; Parsons, Ken

    2008-04-01

    When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces.

  14. Melting phenomenon in magneto hydro-dynamics steady flow and heat transfer over a moving surface in the presence of thermal radiation

    Science.gov (United States)

    Reda, G. Abdel-Rahman; M. Khader, M.; Ahmed, M. Megahed

    2013-03-01

    The Lie group method is applied to present an analysis of the magneto hydro-dynamics (MHD) steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal radiation. By using the Lie group method, we have presented the transformation groups for the problem apart from the scaling group. The application of this method reduces the partial differential equations (PDEs) with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations (ODEs) with appropriate boundary conditions. The resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method (FDM). The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.

  15. Melting phenomenon in magneto hydro-dynamics steady flow and heat transfer over a moving surface in the presence of thermal radiation

    Institute of Scientific and Technical Information of China (English)

    Reda G.Abdel-Rahman; M.M.Khader; Ahmed M.Megahed

    2013-01-01

    The Lie group method is applied to present an analysis of the magneto hydro-dynamics (MHD) steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal radiation.By using the Lie group method,we have presented the transformation groups for the problem apart from the scaling group.The application of this method reduces the partial differential equations (PDEs) with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations (ODEs) with appropriate boundary conditions.The resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method (FDM).The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.

  16. Thermal radiation heat transfer (3rd revised and enlarged edition)

    Science.gov (United States)

    Siegel, Robert; Howell, John R.

    1992-01-01

    This book first reviews the overall aspects and background information related to thermal radiation heat transfer and incorporates new general information, advances in analytical and computational techniques, and new reference material. Coverage focuses on radiation from opaque surfaces, radiation interchange between various types of surfaces enclosing a vacuum or transparent medium, and radiation including the effects of partially transmitting media, such as combustion gases, soot, or windows. Boundary conditions and multiple layers are discussed with information on radiation in materials with nonunity refractive indices.

  17. GEWEX Surface Radiation Budget (SRB)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NASA/GEWEX Surface Radiation Budget (SRB) Release-3.0 data sets contains global 3-hourly, daily, monthly/3-hourly, and monthly averages of surface and top-of...

  18. DETERMINATION OF RADIATOR COOLING SURFACE

    Directory of Open Access Journals (Sweden)

    A. I. Yakubovich

    2009-01-01

    Full Text Available The paper proposes a methodology for calculation of a radiator cooling surface with due account of heat transfer non-uniformity on depth of its core. Calculation of radiator cooling surfaces of «Belarus-1221» and «Belarus-3022» tractors has been carried out in the paper. The paper also advances standard size series of radiators for powerful «Belarus» tractor type.

  19. Effects of Thermophoresis, Viscous Dissipation and Joule Heating on Steady MHD Flow over an Inclined Radiative Isothermal Permeable Surface with Variable Thermal Conductivity

    Directory of Open Access Journals (Sweden)

    Machireddy Gnaneswara Reddy

    2014-01-01

    Full Text Available A two-dimensional mathematical model is presented for the laminar heat and mass transfer of an electrically-conducting, viscous and Joule (Ohmic heating fluid over an inclined radiate isothermal permeable surface in the presence of the variable thermal conductivity, thermophoresis and heat generation. The Talbot- Cheng-Scheffer-Willis formulation (1980 is used to introduce a thermophoretic coefficient into the concentration boundary layer equation. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in a single independent variable . The resulting coupled nonlinear equations are solved under appropriate transformed boundary conditions using the Runge-Kutta fourth order along with shooting method. Comparisons with previously published work are performed and the results are found to be in very good agreement. Computations are performed for a wide range of the governing flow parameters, viz., magnetic field parameter, thermophoretic coefficient (a function of Knudsen number, Eckert number (viscous heating effect, angle of inclination, thermal conductivity parameter, heat generation parameter and Schmidt number. The present problem finds applications in optical fiber fabrication, aerosol filter precipitators, particle deposition on hydronautical blades, semiconductor wafer design, thermo-electronics and magnetohydrodynamic energy generators.

  20. Sound radiation from finite surfaces

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2013-01-01

    A method to account for the effect of finite size in acoustic power radiation problem of planar surfaces using spatial windowing is developed. Cremer and Heckl presents a very useful formula for the power radiating from a structure using the spatially Fourier transformed velocity, which combined...... with spatially windowing of a plane waves can be used to take into account the finite size. In the present paper, this is developed by means of a radiation impedance for finite surfaces, that is used instead of the radiation impedance for infinite surfaces. In this way, the spatial windowing is included...... in the radiation formula directly, and no pre-windowing is needed. Examples are given for the radiation efficiency, and the results are compared with results found in the literature....

  1. Vesta surface thermal properties map

    Science.gov (United States)

    Capria, Maria Teresa; Tosi, F.; De Santis, Maria Cristina; Capaccioni, F.; Ammannito, E.; Frigeri, A.; Zambon, F; Fonte, S.; Palomba, E.; Turrini, D.; Titus, T.N.; Schroder, S.E.; Toplis, M.J.; Liu, J.Y.; Combe, J.-P.; Raymond, C.A.; Russell, C.T.

    2014-01-01

    The first ever regional thermal properties map of Vesta has been derived from the temperatures retrieved by infrared data by the mission Dawn. The low average value of thermal inertia, 30 ± 10 J m−2 s−0.5 K−1, indicates a surface covered by a fine regolith. A range of thermal inertia values suggesting terrains with different physical properties has been determined. The lower thermal inertia of the regions north of the equator suggests that they are covered by an older, more processed surface. A few specific areas have higher than average thermal inertia values, indicative of a more compact material. The highest thermal inertia value has been determined on the Marcia crater, known for its pitted terrain and the presence of hydroxyl in the ejecta. Our results suggest that this type of terrain can be the result of soil compaction following the degassing of a local subsurface reservoir of volatiles.

  2. 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

  3. Radiation oxidation and subsequent thermal curing of polyacrylonitrile fiber

    Science.gov (United States)

    Liu, Weihua; Wang, Mouhua; Xing, Zhe; Wu, Guozhong

    2014-01-01

    Polyacrylonitrile (PAN) fibers were exposed to gamma-ray irradiation at room temperature under vacuum, air and oxygen to investigate the radiation oxidation effects on PAN fibers. Radiation-induced oxidation degradation and crosslinking was evaluated by measuring the gel fraction. It was found that radiation oxidation took place mainly on the fiber surface due to the limited penetration of oxygen into PAN fibers from the surface, and the oxidation thickness increased with the oxygen pressure. Chain scission was dominant in the oxidized area, and crosslinking occurred in the inner part of the fibers. However, the oxidized regions of the fibers can be converted to gel via crosslinking by thermal curing at 160 °C in a N2 atmosphere. Higher extents of radiation oxidation degradation led to a greater increase in the gel fraction. These results suggest that the radiation treatment of PAN fibers prior to thermal oxidation may be useful for manufacturing carbon fibers.

  4. Phase-change radiative thermal diode

    CERN Document Server

    Ben-Abdallah, Philippe

    2013-01-01

    A thermal diode transports heat mainly in one preferential direction rather than in the opposite direction. This behavior is generally due to the non-linear dependence of certain physical properties with respect to the temperature. Here we introduce a radiative thermal diode which rectifies heat transport thanks to the phase transitions of materials. Rectification coefficients greater than 70% and up to 90% are shown, even for small temperature differences. This result could have important applications in the development of futur contactless thermal circuits or in the conception of radiative coatings for thermal management.

  5. Geometric doppler effect: spin-split dispersion of thermal radiation.

    Science.gov (United States)

    Dahan, Nir; Gorodetski, Yuri; Frischwasser, Kobi; Kleiner, Vladimir; Hasman, Erez

    2010-09-24

    A geometric Doppler effect manifested by a spin-split dispersion relation of thermal radiation is observed. A spin-dependent dispersion splitting was obtained in a structure consisting of a coupled thermal antenna array. The effect is due to a spin-orbit interaction resulting from the dynamics of the surface waves propagating along the structure whose local anisotropy axis is rotated in space. The observation of the spin-symmetry breaking in thermal radiation may be utilized for manipulation of spontaneous or stimulated emission.

  6. Enhancing radiative energy transfer through thermal extraction

    Directory of Open Access Journals (Sweden)

    Tan Yixuan

    2016-06-01

    Full Text Available 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.

  7. The influence of the solar radiation model on the calcutated solar radiation from a horizontal surface to a tilted surface

    DEFF Research Database (Denmark)

    Andersen, Elsa; Lund, Hans; Furbo, Simon

    2004-01-01

    in the calculation. The weather data are measured at the solar radiation measurement station, SMS at the Department of Civil Engineering at the Technical University of Denmark. In this study the weather data are combined with solar collector calculations based on solar collector test carried out at Solar Energy......Measured solar radiation data are most commonly available as total solar radiation on a horizontal surface. When using solar radiation measured on horizontal to calculate the solar radiation on tilted surfaces and thereby the thermal performance of different applications such as buildings and solar...... heating systems, different solar radiation models can be used. The calculation of beam radiation from a horizontal surface to a tilted surface can be done exactly whereas different solar radiation models can calculate the sky diffuse radiation. The sky diffuse radiation can either be assumed evenly...

  8. Numerical study of chemically reacting unsteady Casson fluid flow past a stretching surface with cross diffusion and thermal radiation

    Science.gov (United States)

    Pushpalatha, K.; Ramana Reddy, J. V.; Sugunamma, V.; Sandeep, N.

    2017-04-01

    The problem of an unsteady MHD Casson fluid flow towards a stretching surface with cross diffusion effects is considered. The governing partial differential equations are converted into a set of nonlinear coupled ordinary differential equations with the help of suitable similarity transformations. Further, these equations have been solved numerically by using Runge-Kutta fourth order method along with shooting technique. Finally, we studied the influence of various non-dimensional governing parameters on the flow field through graphs and tables. Results indicate that Dufour and Soret numbers have tendency to enhance the fluid velocity. It is also found that Soret number enhances the heat transfer rate where as an opposite result is observed with Casson parameter. A comparison of the present results with the previous literature is also tabulated to show the accuracy of the results.

  9. The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Spuckler, Charles M.

    2008-01-01

    The lattice and radiation conductivity of thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the apparent thermal conductivity of the coating to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature and the scattering and absorption properties of the coating material. High temperature scattering and absorption of the coating systems can also be derived based on the testing results using the modeling approach. The model prediction is found to have good agreement with experimental observations.

  10. Preliminary Thermal Design of Cryogenic Radiation Shielding

    Science.gov (United States)

    Li, Xiaoyi; Mustafi, Shuvo; Boutte, Alvin

    2015-01-01

    Cryogenic Hydrogen Radiation Shielding (CHRS) is the most mass efficient material radiation shielding strategy for human spaceflight beyond low Earth orbit (LEO). Future human space flight, mission beyond LEO could exceed one year in duration. Previous radiation studies showed that in order to protect the astronauts from space radiation with an annual allowable radiation dose less than 500 mSv, 140 kgm2 of polyethylene is necessary. For a typical crew module that is 4 meter in diameter and 8 meter in length. The mass of polyethylene radiation shielding required would be more than 17,500 kg. The same radiation study found that the required hydrogen shielding for the same allowable radiation dose is 40 kgm2, and the mass of hydrogen required would be 5, 000 kg. Cryogenic hydrogen has higher densities and can be stored in relatively small containment vessels. However, the CHRS system needs a sophisticated thermal system which prevents the cryogenic hydrogen from evaporating during the mission. This study designed a cryogenic thermal system that protects the CHRS from hydrogen evaporation for one to up to three year mission. The design also includes a ground based cooling system that can subcool and freeze liquid hydrogen. The final results show that the CHRS with its required thermal protection system is nearly half of the mass of polyethylene radiation shielding.

  11. Non-thermal WIMPs as dark radiation

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Farinaldo S. [Department of Physics and Santa Cruz Institute for Particle Physics University of California, Santa Cruz, CA 95064 (United States)

    2014-06-24

    It has been thought that only light species could behave as radiation and account for the dark radiation observed recently by Planck, WMAP9, South Pole and ATACAMA telescopes. In this work we will show GeV scale WIMPs can plausibly account for the dark radiation as well. Heavy WIMPs might mimic the effect of a half neutrino species if some fraction of them are produced non-thermally after their thermal freeze-out. In addition, we will show how BBN, CMB and Structure Formation bounds might be circumvented.

  12. 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.

  13. Thermal Radiative Properties of Xonotlite Insulation Material

    Institute of Scientific and Technical Information of China (English)

    Xinxin ZHANG; Gaosheng WEI; Fan YU

    2005-01-01

    This paper presents experimental results of thermal radiative properties of xonotlite-type calcium silicate insulation material. Transmittance spectra were first taken using Fourier transform infrared spectrometer (FTIR)for the samples with ρ = 234 kg/m3. Specific extinction coefficient spectra were then obtained by applying Beer's law.Finally,by using the diffusion approximation,the specific Rossland mean extinction coefficients and radiative thermal conductivities were obtained for various temperatures. The results show that the specific spectral extinction coefficient of xonotlite is larger than 7 m2/kg in the whole measured spectra, and diffusion approximation equation is a reasonable description of radiative heat transfer in xonotlite insulation material. The specific Rossland mean extinction coefficient of xonotlite has a maximum ualue at 400 K and the radiative thermal conductivity is almost proportional to the cube of temperature.

  14. Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer

    Science.gov (United States)

    Pugel, Diane

    2011-01-01

    This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous

  15. Cellulose destruction under successive thermal and radiation treatment. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ershov, B.G.; Komarov, V.B.

    1985-02-01

    The influence of successive thermal and radiation effect on cellulose is investigated. The samples were ..gamma.. irradiated (/sup 60/Co) with a dose rate of 20 kGy/h (the absorbed doses ranged from 0 to 80 kGy) and heated up to 190 deg C. It is shown that the attainment of the same destruction depth for the heated-up cellulose occurs at noticeably lower absorbed doses than for the cellulose which has not been subjected to thermal treatment. For successive thermal and radiation treatment of cellulose the ratio S=S therm.+Ssub(rad) where S is a number of broken bonds in a macromolecule is correct. The radiation-chemical yield of cellulose destruction is determined to be: G=7.3 +- 0.1 mol/100 eV.

  16. Radiation Shielding for Nuclear Thermal Propulsion

    Science.gov (United States)

    Caffrey, Jarvis A.

    2016-01-01

    Design and analysis of radiation shielding for nuclear thermal propulsion has continued at Marshall Space Flight Center. A set of optimization tools are in development, and strategies for shielding optimization will be discussed. Considerations for the concurrent design of internal and external shielding are likely required for a mass optimal shield design. The task of reducing radiation dose to crew from a nuclear engine is considered to be less challenging than the task of thermal mitigation for cryogenic propellant, especially considering the likely implementation of additional crew shielding for protection from solar particles and cosmic rays. Further consideration is thus made for the thermal effects of radiation absorption in cryogenic propellant. Materials challenges and possible methods of manufacturing are also discussed.

  17. Global radiation on inclined surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, S.; Rattunde, R.; Krochmann, J.

    1981-02-01

    Radiation intensities and irradiances resulting from global radiation incident on inclined surfaces are important for solar energy use in heating and air conditioning of buildings. Both quantities are a function of astronomical, meteorological, and other parameters of the insolation geometry. Methods of calculation for cloudy, clear, and partly cloudy skies are described which may be carried out with the aid of programmable desk computers. Computer programs have been specially developed for this purpose. Their results are compared with other theoretical data and with data of the Hamburg Meteorological Observatory. Simplified results obtained with the aid of tables are found to be inaccurate while the computer programs provide satisfactory results.

  18. Thermal radiation effect on thermal explosion in gas containing fuel droplets

    Science.gov (United States)

    Goldfarb, Igor; Gol'dshtein, Vladimir; Kuzmenko, Grigory; Sazhin, Sergei

    1999-12-01

    The effect of thermal radiation on the dynamics of a thermal explosion of a flammable gas mixture with the addition of volatile fuel droplets is studied. This is based on an original physical model of self-ignition. The thermal radiation energy exchange between the evaporating surface of the fuel droplets and burning gas is described using the P-1 model with Marshak boundary conditions. The original system of equations describing the effects of heating, evaporation and the combustion of fuel droplets is simplified to enable their analysis using asymptotic methods. The mathematical formulation is eventually reduced to a singularly perturbed system of ordinary differential equations. This allows us to apply the advanced geometric asymptotic technique (integral manifold method) for the qualitative analysis of the behaviour of the solution. Possible types of dynamic behaviour of the system are classified and parametric regions of their existence are determined analytically. The main attention is concentrated on the situations where delays might occur before the final ignition. Our study is focused on the impact of thermal radiation on the delay time. The dimensionless parameter responsible for the impact of thermal radiation is singled out and analysed. The dependence of the delay characteristics on the physical parameters of the problem under consideration is analysed. An explicit expression for the minimum time delay of the thermal explosion of fuel droplets in the presence of thermal radiation is derived and applied to the thermal explosion of n-decane and tetralin droplets. It is pointed out that the effects of thermal radiation can be significant, especially at high temperatures, and cannot be ignored in the analysis of this phenomenon.

  19. Evaluation of arctic broadband surface radiation measurements

    OpenAIRE

    N. Matsui; C. N. Long; Augustine, J.; D. Halliwell; T. Uttal; Longenecker, D.; O. Nievergall; Wendell, J.; Albee, R.

    2011-01-01

    The Arctic is a challenging environment for making in-situ radiation measurements. A standard suite of radiation sensors is typically designed to measure the total, direct and diffuse components of incoming and outgoing broadband shortwave (SW) and broadband thermal infrared, or longwave (LW) radiation. Enhancements can include various sensors for measuring irradiance in various narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are...

  20. Effects of Thermal Radiation and Chemical Reaction on MHD Free Convection Flow past a Flat Plate with Heat Source and Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    E.Hemalatha

    2015-09-01

    Full Text Available This paper analyzes the radiation and chemical reaction effects on MHD steady two-dimensional laminar viscous incompressible radiating boundary layer flow over a flat plate in the presence of internal heat generation and convective boundary condition. It is assumed that lower surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the upper surface with a heat source that decays exponentially. The Rosseland approximation is used to describe radiative heat transfer as we consider optically thick fluids. The governing boundary layer equations are transformed into a system of ordinary differential equations using similarity transformations, which are then solved numerically by employing fourth order Runge-Kutta method along with shooting technique. The effects of various material parameters on the velocity, temperature and concentration as well as the skin friction coefficient, the Nusselt number, the Sherwood number and the plate surface temperature are illustrated and interpreted in physical terms. A comparison of present results with previously published results shows an excellent agreement.

  1. Radiative magnetized thermal conduction fronts

    Science.gov (United States)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The evolution of plane-parallel magnetized thermal conduction fronts in the interstellar medium (ISM) was studied. Separating the coronal ISM phase and interstellar clouds, these fronts have been thought to be the site of the intermediate-temperature regions whose presence was inferred from O VI absorption-line studies. The front evolution was followed numerically, starting from the initial discontinuous temperature distribution between the hot and cold medium, and ending in the final cooling stage of the hot medium. It was found that, for the typical ISM pressure of 4000 K/cu cm and the hot medium temperature of 10 to the 6th K, the transition from evaporation to condensation in a nonmagnetized front occurs when the front thickness is 15 pc. This thickness is a factor of 5 smaller than previously estimated. The O VI column densities in both evaporative and condensation stages agree with observations if the initial hot medium temperature Th exceeds 750,000 K. Condensing conduction fronts give better agreement with observed O VI line profiles because of lower gas temperatures.

  2. The thermal radiation from dynamic black holes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using the related formula of dynamic black holes, the instantaneous radiation energy density of the general spherically symmetric charged dynamic black hole and the arbitrarily accelerating charged dynamic black hole is calculated. It is found that the instantaneous radiation energy density of black hole is always proportional to the quartic of the temperature of event horizon in the same direction. The proportional coefficient of generalized Stefan-Boltzmann is no longer a constant, and it becomes a dynamic coefficient that is related to the event horizon changing rate, space-time structure near event horizon and the radiation absorption coefficient of the black hole. It is shown that there should be an internal relation between the gravitational field around black hole and its thermal radiation.

  3. Radiation and thermal stabilities of adenine nucleotides.

    Science.gov (United States)

    Demidov, V V; Potaman, V N; Solyanina, I P; Trofimov, V I

    1995-03-01

    We have investigated in detail radiation and thermal stabilities and transformations of adenosine mono- and triphosphates in liquid and frozen solid aqueous solutions within a wide range of absorbed radiation dose (up to 75 kGy) and temperature (up to 160 degrees C). Dephosphorylation is the main pathway of high temperature hydrolysis of adenine nucleotides. Basic thermodynamic and kinetic parameters of this process have been determined. Radiolysis of investigated compounds at room temperature results in scission of N-glycosidic bond with a radiation yield about of 1 mol/100 eV. Solution freezing significantly enhances radiation stability of nucleotides as well as other biomolecules. This circumstance is essential in the discussion of panspermia concepts.

  4. Design and calibration of a novel transient radiative heat flux meter for a spacecraft thermal test

    Science.gov (United States)

    Sheng, Chunchen; Hu, Peng; Cheng, Xiaofang

    2016-06-01

    Radiative heat flux measurement is significantly important for a spacecraft thermal test. To satisfy the requirements of both high accuracy and fast response, a novel transient radiative heat flux meter was developed. Its thermal receiver consists of a central thermal receiver and two thermal guarded annular plates, which ensure the temperature distribution of the central thermal receiver to be uniform enough for reasonably applying lumped heat capacity method in a transient radiative heat flux measurement. This novel transient radiative heat flux meter design can also take accurate measurements regardless of spacecraft surface temperature and incident radiation spectrum. The measurement principle was elaborated and the coefficients were calibrated. Experimental results from testing a blackbody furnace and an Xenon lamp show that this novel transient radiative heat flux meter can be used to measure transient radiative heat flux up to 1400 W/m2 with high accuracy and the response time of less than 10 s.

  5. Evaluation of Arctic broadband surface radiation measurements

    Directory of Open Access Journals (Sweden)

    N. Matsui

    2012-02-01

    Full Text Available The Arctic is a challenging environment for making in-situ surface radiation measurements. A standard suite of radiation sensors is typically designed to measure incoming and outgoing shortwave (SW and thermal infrared, or longwave (LW, radiation. Enhancements may include various sensors for measuring irradiance in narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers that keep sensors and shading devices trained on the sun along its diurnal path. High quality measurements require striking a balance between locating stations in a pristine undisturbed setting free of artificial blockage (such as from buildings and towers and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data in the Arctic include solar tracker malfunctions, rime/frost/snow deposition on the protective glass domes of the radiometers and operational problems due to limited operator access in extreme weather conditions. In this study, comparisons are made between the global and component sum (direct [vertical component] + diffuse SW measurements. The difference between these two quantities (that theoretically should be zero is used to illustrate the magnitude and seasonality of arctic radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both SW and LW measurements. Solutions to these operational problems that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols are proposed.

  6. Effects of thermal radiation and magnetic field on unsteady mixed convection flow and heat transfer over an exponentially stretching surface with suction in the presence of internal heat generation/absorption

    Directory of Open Access Journals (Sweden)

    Elsayed M.A. Elbashbeshy

    2012-10-01

    Full Text Available In this paper, the problem of unsteady laminar two-dimensional boundary layer flow and heat transfer of an incompressible viscous fluid in the presence of thermal radiation, internal heat generation or absorption, and magnetic field over an exponentially stretching surface subjected to suction with an exponential temperature distribution is discussed numerically. The governing boundary layer equations are reduced to a system of ordinary differential equations. New numerical method using Mathematica has been used to solve such system after obtaining the missed initial conditions. Comparison of obtained numerical results is made with previously published results in some special cases, and found to be in a good agreement.

  7. Radiative thermal rectification using superconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Nefzaoui, Elyes, E-mail: elyes.nefzaoui@univ-poitiers.fr; Joulain, Karl, E-mail: karl.joulain@univ-poitiers.fr; Drevillon, Jérémie; Ezzahri, Younès [Institut Pprime, Université de Poitiers-CNRS-ENSMA, 2, Rue Pierre Brousse, Bâtiment B25, TSA 41105, 86073 Poitiers Cedex 9 (France)

    2014-03-10

    Thermal rectification can be defined as an asymmetry in the heat flux when the temperature difference between two interacting thermal reservoirs is reversed. In this Letter, we present a far-field radiative thermal rectifier based on high-temperature superconducting materials with a rectification ratio up to 80%. This value is among the highest reported in literature. Two configurations are examined: a superconductor (Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}) exchanging heat with (1) a black body and (2) another superconductor, YBa{sub 2}Cu{sub 3}O{sub 7} in this case. The first configuration shows a higher maximal rectification ratio. Besides, we show that the two-superconductor rectifier exhibits different rectification regimes depending on the choice of the reference temperature, i.e., the temperature of the thermostat. Presented results might be useful for energy conversion devices, efficient cryogenic radiative insulators engineering, and thermal logical circuits’ development.

  8. High temperature thermal stability of the HfO{sub 2}/Ge (100) interface as a function of surface preparation studied by synchrotron radiation core level photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Chellappan, Rajesh Kumar, E-mail: rajesh.chellappan2@mail.dcu.ie [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Gajula, Durga Rao; McNeill, David [School of Electronics, Electrical Engineering and Computer Science, Queen' s University Belfast (United Kingdom); Hughes, Greg [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2014-02-15

    High resolution soft x-ray photoemission spectroscopy (SXPS) have been used to study the high temperature thermal stability of ultra-thin atomic layer deposited (ALD) HfO{sub 2} layers (∼1 nm) on sulphur passivated and hydrofluoric acid (HF) treated germanium surfaces. The interfacial oxides which are detected for both surface preparations following HfO{sub 2} deposition can be effectively removed by annealing upto 700 °C without any evidence of chemical interaction at the HfO{sub 2}/Ge interface. The estimated valence and conduction band offsets for the HfO{sub 2}/Ge abrupt interface indicated that effective barriers exist to inhibit carrier injection.

  9. Similarity solution to three dimensional boundary layer flow of second grade nanofluid past a stretching surface with thermal radiation and heat source/sink

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589 (Saudi Arabia); Muhammad, Taseer [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Shehzad, S. A., E-mail: ali-qau70@yahoo.com [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2015-01-15

    Development of human society greatly depends upon solar energy. Heat, electricity and water from nature can be obtained through solar power. Sustainable energy generation at present is a critical issue in human society development. Solar energy is regarded one of the best sources of renewable energy. Hence the purpose of present study is to construct a model for radiative effects in three-dimensional of nanofluid. Flow of second grade fluid by an exponentially stretching surface is considered. Thermophoresis and Brownian motion effects are taken into account in presence of heat source/sink and chemical reaction. Results are derived for the dimensionless velocities, temperature and concentration. Graphs are plotted to examine the impacts of physical parameters on the temperature and concentration. Numerical computations are presented to examine the values of skin-friction coefficients, Nusselt and Sherwood numbers. It is observed that the values of skin-friction coefficients are more for larger values of second grade parameter. Moreover the radiative effects on the temperature and concentration are quite reverse.

  10. Mathematical modeling and numerical analysis of thermal distribution in arch dams considering solar radiation effect.

    Science.gov (United States)

    Mirzabozorg, H; Hariri-Ardebili, M A; Shirkhan, M; Seyed-Kolbadi, S M

    2014-01-01

    The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams.

  11. Matrix expression of thermal radiative characteristics for an open complex

    Institute of Scientific and Technical Information of China (English)

    XU; Xiru; (徐希孺); FAN; Wenjie; (范闻捷); &; CHEN; Liangfu; (陈良富)

    2002-01-01

    The directionality of thermal radiance of a homogeneous isothermal non-black plane surface is totally decided by its directional emissivity, which depends on the complex dielectric constant and roughness of surface. It can be expressed by This paper proves that it is necessary to express emissivity by a matrix when a target becomes an inhomogeneous non-isothermal open complex with complicated inner geometric structure. The matrix describes the inner radiative interaction among components accurately and also expresses its thermal radiative directionality and structural characteristics completely. Advantages of matrix expression are as follows: first, the physical mechanics of effective emissivity of an open complex is described in a simple and perfect way; second, it becomes easy to understand the principle and method to retrieve components temperature from multi-angle thermal remotely sensed data; and third, the differences of directionalities between an open complex and a homogeneous isothermal non-black plane body are expressed by just using an effective emissivity matrix instead of an emissivity vector. Formula in classic physics is only the special case of matrix expression; therefore, the matrix is a universal unconditional expression to describe the directionality of thermal radiance.

  12. Surface wave chemical detector using optical radiation

    Science.gov (United States)

    Thundat, Thomas G.; Warmack, Robert J.

    2007-07-17

    A surface wave chemical detector comprising at least one surface wave substrate, each of said substrates having a surface wave and at least one measurable surface wave parameter; means for exposing said surface wave substrate to an unknown sample of at least one chemical to be analyzed, said substrate adsorbing said at least one chemical to be sensed if present in said sample; a source of radiation for radiating said surface wave substrate with different wavelengths of said radiation, said surface wave parameter being changed by said adsorbing; and means for recording signals representative of said surface wave parameter of each of said surface wave substrates responsive to said radiation of said different wavelengths, measurable changes of said parameter due to adsorbing said chemical defining a unique signature of a detected chemical.

  13. On the integral law of thermal radiation

    Science.gov (United States)

    Gusev, Y. V.

    2014-10-01

    The integral law of thermal radiation by finite-size emitters is studied. Two geometrical characteristics of a radiating body or a cavity, its volume and its boundary area, define two terms in its radiance. The term defined by the volume corresponds to the Stefan-Boltzmann law. The term defined by the boundary area is proportional to the third power of temperature and inversely proportional to emitter's effective size, which is defined as the ratio of its volume to its boundary area. This generalized law is valid for arbitrary temperature and effective size. It is shown that the cubic temperature contribution is observed in experiments. This term explains the intrinsic uncertainty of the NPL experiment on radiometric determination of the Stefan-Boltzmann constant. It is also quantitatively confirmed by data from the NIST calibration of cryogenic blackbodies. Its relevance to the size of source effect in optical radiometry is proposed and supported by the experiments on thermal emission from nano-heaters.

  14. Controlling thermal chaos in the mantle by positive feedback from radiative thermal conductivity

    Directory of Open Access Journals (Sweden)

    F. Dubuffet

    2002-01-01

    Full Text Available The thermal conductivity of mantle materials has two components, the lattice component klat from phonons and the radiative component krad due to photons. These two contributions of variable thermal conductivity have a nonlinear dependence in the temperature, thus endowing the temperature equation in mantle convection with a strongly nonlinear character. The temperature derivatives of these two mechanisms have different signs, with ∂klat /∂T negative and dkrad /dT positive. This offers the possibility for the radiative conductivity to control the chaotic boundary layer instabilities developed in the deep mantle. We have parameterized the weight factor between krad and klat with a dimensionless parameter f , where f = 1 corresponds to the reference conductivity model. We have carried out two-dimensional, time-dependent calculations for variable thermal conductivity but constant viscosity in an aspect-ratio 6 box for surface Rayleigh numbers between 106 and 5 × 106. The averaged Péclet numbers of these flows lie between 200 and 2000. Along the boundary in f separating the chaotic and steady-state solutions, the number decreases and the Nusselt number increases with internal heating, illustrating the feedback between internal heating and radiative thermal conductivity. For purely basal heating situation, the time-dependent chaotic flows become stabilized for values of f of between 1.5 and 2. The bottom thermal boundary layer thickens and the surface heat flow increases with larger amounts of radiative conductivity. For magnitudes of internal heating characteristic of a chondritic mantle, much larger values of f , exceeding 10, are required to quench the bottom boundary layer instabilities. By isolating the individual conductive mechanisms, we have ascertained that the lattice conductivity is partly responsible for inducing boundary layer instabilities, while the radiative conductivity and purely depth-dependent conductivity exert a stabilizing

  15. Thermodynamics and energy conversion of near-field thermal radiation: Maximum work and efficiency bounds

    Directory of Open Access Journals (Sweden)

    Latella Ivan

    2014-01-01

    Full Text Available We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.

  16. Infrared Radiation from Rough Surface

    CERN Document Server

    Ayryan, E A; Oganesyan, K B

    2016-01-01

    We consider generation of diffusive radiation by a charged particle passing through a random stack of plates in the infrared region. Diffusive radiation originates due to multiple scattering of pseudophotons on the plates. To enhance the radiation intensity one needs to make the scattering more effective. For this goal we suggest to use materials with negative dielectric constant .

  17. A toy model linking atmospheric thermal radiation and sea ice growth

    Science.gov (United States)

    Thorndike, A. S.

    1992-01-01

    A simplified analytical model of sea ice growth is presented where the atmosphere is in thermal radiative equilibrium with the ice. This makes the downwelling longwave radiation reaching the ice surface an internal variable rather than a specified forcing. Analytical results demonstrate how the ice state depends on properties of the ice and on the externally specified climate.

  18. Thermal smoothing of rough surfaces in vacuo

    Science.gov (United States)

    Wahl, G.

    1986-01-01

    The derivation of equations governing the smoothing of rough surfaces, based on Mullins' (1957, 1960, and 1963) theories of thermal grooving and of capillarity-governed solid surface morphology is presented. As an example, the smoothing of a one-dimensional sine-shaped surface is discussed.

  19. Thermal imaging method to visualize a hidden painting thermally excited by far infrared radiations

    Science.gov (United States)

    Davin, T.; Wang, X.; Chabane, A.; Pawelko, R.; Guida, G.; Serio, B.; Hervé, P.

    2015-06-01

    The diagnosis of hidden painting is a major issue for cultural heritage. In this paper, a non-destructive active infrared thermographic technique was considered to reveal paintings covered by a lime layer. An extended infrared spectral range radiation was used as the excitation source. The external long wave infrared energy source delivered to the surface is then propagated through the material until it encounters a painting zone. Due to several thermal effects, the sample surface then presents non-uniformity patterns. Using a high sensitive infrared camera, the presence of covered pigments can thus be highlighted by the analysis of the non-stationary phenomena. Reconstituted thermal contrast images of mural samples covered by a lime layer are shown.

  20. Multipole surface solitons in layered thermal media

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2008-01-01

    We address the existence and properties of multipole solitons localized at a thermally insulating interface between uniform or layered thermal media and a linear dielectric. We find that in the case of uniform media, only surface multipoles with less than three poles can be stable. In contrast, we reveal that periodic alternation of the thermo-optic coefficient in layered thermal media makes possible the stabilization of higher order multipoles.

  1. An equivalent ground thermal test method for single-phase fluid loop space radiator

    Directory of Open Access Journals (Sweden)

    Ning Xianwen

    2015-02-01

    Full Text Available Thermal vacuum test is widely used for the ground validation of spacecraft thermal control system. However, the conduction and convection can be simulated in normal ground pressure environment completely. By the employment of pumped fluid loops’ thermal control technology on spacecraft, conduction and convection become the main heat transfer behavior between radiator and inside cabin. As long as the heat transfer behavior between radiator and outer space can be equivalently simulated in normal pressure, the thermal vacuum test can be substituted by the normal ground pressure thermal test. In this paper, an equivalent normal pressure thermal test method for the spacecraft single-phase fluid loop radiator is proposed. The heat radiation between radiator and outer space has been equivalently simulated by combination of a group of refrigerators and thermal electrical cooler (TEC array. By adjusting the heat rejection of each device, the relationship between heat flux and surface temperature of the radiator can be maintained. To verify this method, a validating system has been built up and the experiments have been carried out. The results indicate that the proposed equivalent ground thermal test method can simulate the heat rejection performance of radiator correctly and the temperature error between in-orbit theory value and experiment result of the radiator is less than 0.5 °C, except for the equipment startup period. This provides a potential method for the thermal test of space systems especially for extra-large spacecraft which employs single-phase fluid loop radiator as thermal control approach.

  2. An equivalent ground thermal test method for single-phase fluid loop space radiator

    Institute of Scientific and Technical Information of China (English)

    Ning Xianwen; Wang Yuying; Zhang Jiaxun; Liu Dongxiao

    2015-01-01

    Thermal vacuum test is widely used for the ground validation of spacecraft thermal con-trol system. However, the conduction and convection can be simulated in normal ground pressure environment completely. By the employment of pumped fluid loops’ thermal control technology on spacecraft, conduction and convection become the main heat transfer behavior between radiator and inside cabin. As long as the heat transfer behavior between radiator and outer space can be equivalently simulated in normal pressure, the thermal vacuum test can be substituted by the nor-mal ground pressure thermal test. In this paper, an equivalent normal pressure thermal test method for the spacecraft single-phase fluid loop radiator is proposed. The heat radiation between radiator and outer space has been equivalently simulated by combination of a group of refrigerators and thermal electrical cooler (TEC) array. By adjusting the heat rejection of each device, the relationship between heat flux and surface temperature of the radiator can be maintained. To verify this method, a validating system has been built up and the experiments have been carried out. The results indi-cate that the proposed equivalent ground thermal test method can simulate the heat rejection per-formance of radiator correctly and the temperature error between in-orbit theory value and experiment result of the radiator is less than 0.5 ?C, except for the equipment startup period. This provides a potential method for the thermal test of space systems especially for extra-large space-craft which employs single-phase fluid loop radiator as thermal control approach.

  3. Non-thermal Hawking radiation from the Kerr black hole

    Institute of Scientific and Technical Information of China (English)

    HAN Yi-Wen; HAO Jia-Bo

    2009-01-01

    We present a short and direct derivation of Hawking radiation by using the Damour-Ruffini method, as taking into account the self-gravitational interaction from the Kerr black hole. It is found that the radiation is not exactly thermal, and because the derivation obeys conservation laws, the non-thermal Hawking radiation can carry information from the black hole. So it can be used to explain the black hole information paradox, and the process satisfies unitary.

  4. On orbit surfacing of thermal control surfaces

    Science.gov (United States)

    Racette, G. W.

    1984-01-01

    Substrates to be contaminated and contamination source were prepared. Additional information on paint spray method apparatus was obtained. Silver teflon second surface mirror samples and S 13 GLO paint samples were mounted, photographed under the microscope and measured to establish baseline data. Atomic oxygen cleaning and spray painting are being considered. Electrostatic powder and plasma spray coating systems appear to have serious drawbacks.

  5. Thermal radiosensitization in radiation-sensitive mutant mouse leukemic cells

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Toshikazu (Hiroshima Univ. (Japan). School of Dentistry)

    1994-06-01

    This study investigated thermal, radiation, and combined thermal radiation sensitization of mouse leukemic cells, L5178Y, and radiation-sensitive mutant cells, LX830. Radiation sensitivity (D[sub 0]) values were 0.41 Gy for LX830 and 1.39 Gy for L5178Y, with the ratio of D[sub 0] values in LX830 to in L5178Y being 3.4. Thus, LX830 was more radiosensitive than L5178Y. LX830 showed no shouldered survival curves. Although sublethal damage (SLD) repair was seen to the almost same degree in both LX830 and L5178Y, potential lethal damage (PLD) repair was scarcely observed in LX830. Both cell lines were similar in thermal sensitivity (T[sub 0]). Eosine staining suggested that cell killing due to hyperthermia had occurred in the interphase in both LX830 and L5178Y. L5178Y showed thermal sensitivity low in the G1 phase and high in the S phase; on the contrary, LX830 showed it high in the G1 phase and low in the S phase. Thermal radiosensitization was similar in both cell lines, although there was a great difference in radiation sensitivity between the cell lines. The difference in radiation sensitivity (D[sub 0]) between L5178Y and LX830 became small when radiation was given at the time of the maximum thermal resistance. This seemed to contribute to a decrease in radiation sensitivity in LX830. It can be concluded that thermal radiosensitization depends on thermal sensitivity and that radiation sensitivity decreases in radiation-sensitive cells when exposed to irradiation at the time of thermal resistance. (N.K.).

  6. Thermal effects of radiation from cellular telephones

    Science.gov (United States)

    Wainwright, Peter

    2000-08-01

    A finite element thermal model of the head has been developed to calculate temperature rises generated in the brain by radiation from cellular telephones and similar electromagnetic devices. A 1 mm resolution MRI dataset was segmented semiautomatically, assigning each volume element to one of ten tissue types. A finite element mesh was then generated using a fully automatic tetrahedral mesh generator developed at NRPB. There are two sources of heat in the model: firstly the natural metabolic heat production; and secondly the power absorbed from the electromagnetic field. The SAR was derived from a finite difference time domain model of the head, coupled to a model `mobile phone', namely a quarter-wavelength antenna mounted on a metal box. The steady-state temperature distribution was calculated using the standard Pennes `bioheat equation'. In the normal cerebral cortex the high blood perfusion rate serves to provide an efficient cooling mechanism. In the case of equipment generally available to the public, the maximum temperature rise found in the brain was about 0.1 °C. These results will help in the further development of criteria for exposure guidelines, and the technique developed may be used to assess temperature rises associated with SARs for different types of RF exposure.

  7. Instrument for thermal radiation flux measurement in high temperature gas flow (Cuernavaca instrument)

    Energy Technology Data Exchange (ETDEWEB)

    Afgan, N.H. [Universidade Tecnica, Lisbon (Portugal); Leontiev, A.I. [Moscow State Technical University (Russian Federation)

    1995-05-01

    A new instrument for hemispherical radiation heat flux measurement is proposed. It is based on the theory of blow of the boundary layer, taking into account that at the critical mass flow rate through the porous surface the thermal boundary layer is blown off and only radiation flux from high temperature gases reaches the porous surface. With the measurement of blow of gas flow and the temperature of the porous material, the respective heat flux is obtained. (author)

  8. Determination of Radiative Thermal Conductivity in Needlepunched Nonwovens

    Directory of Open Access Journals (Sweden)

    Rahul Vallabh

    2008-12-01

    Full Text Available Radiation heat transfer is found to be the dominant mode of heat transfer at temperatures higher than 400-500K [11]. Convection heat transfer being negligible in nonwovens, effective thermal conductivity is given by the sum of its conduction and radiation components. In this research two methods were identified to determine radiative thermal conductivity of needlepunched samples made from Nomex fibers. The first method involved the determination of radiative thermal conductivity using effective (total thermal conductivity determined using a Guarded Hot Plate (GHP instrument. In the second method radiative thermal conductivity was estimated using the extinction coefficient of samples. The extinction coefficient was determined by using direct transmission measurements made using a Fourier Transform InfraRed (FTIR spectrometer. Results confirmed that radiation was the dominant mode of heat transfer at temperatures higher than 535 K. The conduction component of effective thermal conductivity did not change much in the range of densities tested. Empirical models for predicting the temperature difference across thickness of the fabric and the radiative thermal conductivity with R-square values of 0.94 and 0.88 respectively showed that fabric density, fabric thickness, fiber fineness, fiber length, mean pore size and applied temperature were found to have significant effect on the effective thermal conductivity and its radiation component. Though a high correlation between the results of Method 1 (Guarded Hot Plate and Method 2 (FTIR was not seen, the absorbance measurements made using the FTIR spectrometer were found to have significant effect on the radiative thermal conductivity.

  9. The Thermal Sunyaev-Zeldovich Effect of Primordial Recombination Radiation

    CERN Document Server

    Kholupenko, E E; Ivanchik, A V; Varshalovich, D A

    2014-01-01

    It is well known that recombination radiation of primordial hydrogen-helium plasma leads to the distortions of the planckian spectrum shape of the cosmic microwave background radiation (CMB). We discuss the thermal Sunayev-Zeldovich (SZ) effect with taking into account primordial recombination radiation (PRR). Since in the thermal SZ effect the redistribution of the photons depends on the derivatives of the spectrum, the value of relative correction to SZ effect due to PRR significantly higher than relative corrections due to PRR in the initial spectrum. Calculations of corrections to the thermal SZ effect due to PRR show that depending on the cluster parameters: 1) in the range of frequencies $\

  10. Classical Physics of Thermal Scalar Radiation in Two Spacetime Dimensions

    CERN Document Server

    Boyer, Timothy H

    2010-01-01

    Thermal scalar radiation in two spacetime dimensions is treated within relativistic classical physics. Part I involves an inertial frame where are given the analogues both of Boltzmann's derivation of the Stefan-Boltzmann law and also Wien's derivation of the displacement theorem using the scaling of relativitic radiation theory. Next the spectrum of classical scalar zero-point radiation in an inertial frame is derived both from scale invariance and from Lorentz invariance. Part II involves the behavior of thermal radiation in a coordinate frame undergoing (relativistic) constant acceleration, a Rindler frame. The radiation normal modes in a Rindler frame are obtained. The classical zero-point radiation of inertial frames is transformed over to the coordinates of a Rindler frame. Although for zero-point radiation the two-field correlation function at different spatial points at a single time is the same between inertial and Rindler frames, the correlation function at two different times at a single Rindler sp...

  11. Evaluation of arctic broadband surface radiation measurements

    Directory of Open Access Journals (Sweden)

    N. Matsui

    2011-08-01

    Full Text Available The Arctic is a challenging environment for making in-situ radiation measurements. A standard suite of radiation sensors is typically designed to measure the total, direct and diffuse components of incoming and outgoing broadband shortwave (SW and broadband thermal infrared, or longwave (LW radiation. Enhancements can include various sensors for measuring irradiance in various narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers that rotate sensors and shading devices that track the sun. High quality measurements require striking a balance between locating sensors in a pristine undisturbed location free of artificial blockage (such as buildings and towers and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data include solar tracker malfunctions, rime/frost/snow deposition on the instruments and operational problems due to limited operator access in extreme weather conditions. In this study, a comparison is made between the global and component sum (direct [vertical component] + diffuse shortwave measurements. The difference between these two quantities (that theoretically should be zero is used to illustrate the magnitude and seasonality of radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both shortwave and longwave measurements. Solutions to these operational problems are proposed that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols.

  12. Thermal Radiation of a General Non-stationary Black Hole

    Institute of Scientific and Technical Information of China (English)

    杨成全; 任秦安; 赵峥

    1994-01-01

    The thermal radiation of the most general non-stationary black holes is discussed in this paper.The universal representatives determining the location of an event horizon and the temperature function are given.

  13. Integral Radiators for Next Generation Thermal Control Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Integral radiators integrate the primary structural system and the thermal rejection system into a dual function subsystem allowing for reduced weight. The design of...

  14. Thermal radiation in one-dimensional photonic quasicrystals with graphene

    Science.gov (United States)

    Costa, C. H.; Vasconcelos, M. S.; Fulco, U. L.; Albuquerque, E. L.

    2017-10-01

    In this work we investigate the thermal power spectra of the electromagnetic radiation through one-dimensional stacks of dielectric layers, with graphene at their interfaces, arranged according to a quasiperiodic structure obeying the Fibonacci (FB), Thue-Morse (TM) and double-period (DP) sequences. The thermal radiation power spectra are determined by means of a theoretical model based on a transfer matrix formalism for both normal and oblique incidence geometries, considering the Kirchhoff's law of thermal radiation. A systematic study of the consequences of the graphene layers in the thermal emittance spectra is presented and discussed. We studied also the radiation spectra considering the case where the chemical potential is changed in order to tune the omnidirectional photonic band gap.

  15. D Surface Generation from Aerial Thermal Imagery

    Science.gov (United States)

    Khodaei, B.; Samadzadegan, F.; Dadras Javan, F.; Hasani, H.

    2015-12-01

    Aerial thermal imagery has been recently applied to quantitative analysis of several scenes. For the mapping purpose based on aerial thermal imagery, high accuracy photogrammetric process is necessary. However, due to low geometric resolution and low contrast of thermal imaging sensors, there are some challenges in precise 3D measurement of objects. In this paper the potential of thermal video in 3D surface generation is evaluated. In the pre-processing step, thermal camera is geometrically calibrated using a calibration grid based on emissivity differences between the background and the targets. Then, Digital Surface Model (DSM) generation from thermal video imagery is performed in four steps. Initially, frames are extracted from video, then tie points are generated by Scale-Invariant Feature Transform (SIFT) algorithm. Bundle adjustment is then applied and the camera position and orientation parameters are determined. Finally, multi-resolution dense image matching algorithm is used to create 3D point cloud of the scene. Potential of the proposed method is evaluated based on thermal imaging cover an industrial area. The thermal camera has 640×480 Uncooled Focal Plane Array (UFPA) sensor, equipped with a 25 mm lens which mounted in the Unmanned Aerial Vehicle (UAV). The obtained results show the comparable accuracy of 3D model generated based on thermal images with respect to DSM generated from visible images, however thermal based DSM is somehow smoother with lower level of texture. Comparing the generated DSM with the 9 measured GCPs in the area shows the Root Mean Square Error (RMSE) value is smaller than 5 decimetres in both X and Y directions and 1.6 meters for the Z direction.

  16. Thermal Tomography of Asteroid Surface Structure

    Science.gov (United States)

    Harris, Alan W.; Drube, Line

    2016-12-01

    Knowledge of the surface thermal inertia of an asteroid can provide insight into its surface structure: porous material has a lower thermal inertia than rock. We develop a means to estimate thermal inertia values of asteroids and use it to show that thermal inertia appears to increase with spin period in the case of main-belt asteroids (MBAs). Similar behavior is found on the basis of thermophysical modeling for near-Earth objects (NEOs). We interpret our results in terms of rapidly increasing material density and thermal conductivity with depth, and provide evidence that thermal inertia increases by factors of 10 (MBAs) to 20 (NEOs) within a depth of just 10 cm. Our results are consistent with a very general picture of rapidly changing material properties in the topmost regolith layers of asteroids and have important implications for calculations of the Yarkovsky effect, including its perturbation of the orbits of potentially hazardous objects and those of asteroid family members after the break-up event. Evidence of a rapid increase of thermal inertia with depth is also an important result for studies of the ejecta-enhanced momentum transfer of impacting vehicles (“kinetic impactors”) in planetary defense.

  17. Passive Collecting of Solar Radiation Energy using Transparent Thermal Insulators, Energetic Efficiency of Transparent Thermal Insulators

    Directory of Open Access Journals (Sweden)

    Smajo Sulejmanovic

    2014-11-01

    Full Text Available This paper explains passive collection of solar radiation energy using transparent thermal insulators. Transparent thermal insulators are transparent for sunlight, at the same time those are very good thermal insulators. Transparent thermal insulators can be placed instead of standard conventional thermal insulators and additionally transparent insulators can capture solar radiation, transform it into heat and save heat just as standard insulators. Using transparent insulators would lead to reduce in usage of fossil fuels and would help protection of an environment and reduce effects of global warming, etc.

  18. Radiators in hydronic heating installations structure, selection and thermal characteristics

    CERN Document Server

    Muniak, Damian Piotr

    2017-01-01

    This book addresses key design and computational issues related to radiators in hydronic heating installations. A historical outline is included to highlight the evolution of radiators and heating technologies. Further, the book includes a chapter on thermal comfort, which is the decisive factor in selecting the ideal heating system and radiator type. The majority of the book is devoted to an extensive discussion of the types and kinds of radiators currently in use, and to identifying the reasons for the remarkable diversity of design solutions. The differences between the solutions are also addressed, both in terms of the effects of operation and of the thermal comfort that needs to be ensured. The book then compares the advantages and disadvantages of each solution, as well as its potential applications. A detailed discussion, supported by an extensive theoretical and mathematical analysis, is presented of the computational relations that are used in selecting the radiator type. The dynamics of radiator hea...

  19. Thermal and concentration stratifications effects in radiative flow of Jeffrey fluid over a stretching sheet.

    Science.gov (United States)

    Hayat, T; Hussain, Tariq; Shehzad, S A; Alsaedi, A

    2014-01-01

    In this article we investigate the heat and mass transfer analysis in mixed convective radiative flow of Jeffrey fluid over a moving surface. The effects of thermal and concentration stratifications are also taken into consideration. Rosseland's approximations are utilized for thermal radiation. The nonlinear boundary layer partial differential equations are converted into nonlinear ordinary differential equations via suitable dimensionless variables. The solutions of nonlinear ordinary differential equations are developed by homotopic procedure. Convergence of homotopic solutions is examined graphically and numerically. Graphical results of dimensionless velocity, temperature and concentration are presented and discussed in detail. Values of the skin-friction coefficient, the local Nusselt and the local Sherwood numbers are analyzed numerically. Temperature and concentration profiles are decreased when the values of thermal and concentration stratifications parameters increase. Larger values of radiation parameter lead to the higher temperature and thicker thermal boundary layer thickness.

  20. Buoyancy induced MHD transient mass transfer flow with thermal radiation

    Directory of Open Access Journals (Sweden)

    N. Ahmed

    2016-09-01

    Full Text Available The problem of a transient MHD free convective mass transfer flow past an infinite vertical porous plate in presence of thermal radiation is studied. The fluid is considered to be a gray, absorbing-emitting radiating but non-scattered medium. Analytical solutions of the equations governing the flow problem are obtained. The effects of mass transfer, suction, radiation and the applied magnetic field on the flow and transport characteristics are discussed through graphs.

  1. Thermal Tomography of Asteroid Surface Structure

    CERN Document Server

    Harris, Alan

    2016-01-01

    Knowledge of the surface thermal inertia of an asteroid can provide insight into surface structure: porous material has a lower thermal inertia than rock. We develop a means to estimate thermal inertia values of asteroids and use it to show that thermal inertia appears to increase with spin period in the case of main-belt asteroids (MBAs). Similar behavior is found on the basis of thermophysical modeling for near-Earth objects (NEOs). We interpret our results in terms of rapidly increasing material density and thermal conductivity with depth, and provide evidence that thermal inertia increases by factors of 10 (MBAs) to 20 (NEOs) within a depth of just 10 cm. Our results are consistent with a very general picture of rapidly changing material properties in the topmost regolith layers of asteroids and have important implications for calculations of the Yarkovsky effect, including its perturbation of the orbits of potentially hazardous objects and those of asteroid family members after the break-up event. Eviden...

  2. Simulation of Nuclear Thermal Radiation with High Intensity Flashlamps.

    Science.gov (United States)

    1979-01-26

    lators. Thermal test requirements often stress only one aspect of nuclear radiation at a time, i.e., maximum flux, UV exposure, etc. Hardness tests...DoE/STTF* furnace at Sandia/Albuquerque is presently capable of low *Solar Thermal Test Facility, now renamed Central Receiver Test Facil- ity (CRTF...Viewpoint," a paper presented at the annual meeting of the Solar Thermal Test Facilities Users Association, Golden, Colorado, April 11-12, 1978. 2. T

  3. TRASYS - THERMAL RADIATION ANALYZER SYSTEM (DEC VAX VERSION WITH NASADIG)

    Science.gov (United States)

    Anderson, G. E.

    1994-01-01

    The Thermal Radiation Analyzer System, TRASYS, is a computer software system with generalized capability to solve the radiation related aspects of thermal analysis problems. TRASYS computes the total thermal radiation environment for a spacecraft in orbit. The software calculates internode radiation interchange data as well as incident and absorbed heat rate data originating from environmental radiant heat sources. TRASYS provides data of both types in a format directly usable by such thermal analyzer programs as SINDA/FLUINT (available from COSMIC, program number MSC-21528). One primary feature of TRASYS is that it allows users to write their own driver programs to organize and direct the preprocessor and processor library routines in solving specific thermal radiation problems. The preprocessor first reads and converts the user's geometry input data into the form used by the processor library routines. Then, the preprocessor accepts the user's driving logic, written in the TRASYS modified FORTRAN language. In many cases, the user has a choice of routines to solve a given problem. Users may also provide their own routines where desirable. In particular, the user may write output routines to provide for an interface between TRASYS and any thermal analyzer program using the R-C network concept. Input to the TRASYS program consists of Options and Edit data, Model data, and Logic Flow and Operations data. Options and Edit data provide for basic program control and user edit capability. The Model data describe the problem in terms of geometry and other properties. This information includes surface geometry data, documentation data, nodal data, block coordinate system data, form factor data, and flux data. Logic Flow and Operations data house the user's driver logic, including the sequence of subroutine calls and the subroutine library. Output from TRASYS consists of two basic types of data: internode radiation interchange data, and incident and absorbed heat rate data

  4. TRASYS - THERMAL RADIATION ANALYZER SYSTEM (CRAY VERSION WITH NASADIG)

    Science.gov (United States)

    Anderson, G. E.

    1994-01-01

    The Thermal Radiation Analyzer System, TRASYS, is a computer software system with generalized capability to solve the radiation related aspects of thermal analysis problems. TRASYS computes the total thermal radiation environment for a spacecraft in orbit. The software calculates internode radiation interchange data as well as incident and absorbed heat rate data originating from environmental radiant heat sources. TRASYS provides data of both types in a format directly usable by such thermal analyzer programs as SINDA/FLUINT (available from COSMIC, program number MSC-21528). One primary feature of TRASYS is that it allows users to write their own driver programs to organize and direct the preprocessor and processor library routines in solving specific thermal radiation problems. The preprocessor first reads and converts the user's geometry input data into the form used by the processor library routines. Then, the preprocessor accepts the user's driving logic, written in the TRASYS modified FORTRAN language. In many cases, the user has a choice of routines to solve a given problem. Users may also provide their own routines where desirable. In particular, the user may write output routines to provide for an interface between TRASYS and any thermal analyzer program using the R-C network concept. Input to the TRASYS program consists of Options and Edit data, Model data, and Logic Flow and Operations data. Options and Edit data provide for basic program control and user edit capability. The Model data describe the problem in terms of geometry and other properties. This information includes surface geometry data, documentation data, nodal data, block coordinate system data, form factor data, and flux data. Logic Flow and Operations data house the user's driver logic, including the sequence of subroutine calls and the subroutine library. Output from TRASYS consists of two basic types of data: internode radiation interchange data, and incident and absorbed heat rate data

  5. TRASYS - THERMAL RADIATION ANALYZER SYSTEM (DEC VAX VERSION WITHOUT NASADIG)

    Science.gov (United States)

    Vogt, R. A.

    1994-01-01

    The Thermal Radiation Analyzer System, TRASYS, is a computer software system with generalized capability to solve the radiation related aspects of thermal analysis problems. TRASYS computes the total thermal radiation environment for a spacecraft in orbit. The software calculates internode radiation interchange data as well as incident and absorbed heat rate data originating from environmental radiant heat sources. TRASYS provides data of both types in a format directly usable by such thermal analyzer programs as SINDA/FLUINT (available from COSMIC, program number MSC-21528). One primary feature of TRASYS is that it allows users to write their own driver programs to organize and direct the preprocessor and processor library routines in solving specific thermal radiation problems. The preprocessor first reads and converts the user's geometry input data into the form used by the processor library routines. Then, the preprocessor accepts the user's driving logic, written in the TRASYS modified FORTRAN language. In many cases, the user has a choice of routines to solve a given problem. Users may also provide their own routines where desirable. In particular, the user may write output routines to provide for an interface between TRASYS and any thermal analyzer program using the R-C network concept. Input to the TRASYS program consists of Options and Edit data, Model data, and Logic Flow and Operations data. Options and Edit data provide for basic program control and user edit capability. The Model data describe the problem in terms of geometry and other properties. This information includes surface geometry data, documentation data, nodal data, block coordinate system data, form factor data, and flux data. Logic Flow and Operations data house the user's driver logic, including the sequence of subroutine calls and the subroutine library. Output from TRASYS consists of two basic types of data: internode radiation interchange data, and incident and absorbed heat rate data

  6. Metallic superhydrophobic surfaces via thermal sensitization

    Science.gov (United States)

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

    2017-06-01

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

  7. Thermal computations for electronics conductive, radiative, and convective air cooling

    CERN Document Server

    Ellison, Gordon

    2010-01-01

    IntroductionPrimary mechanisms of heat flowConductionApplication example: Silicon chip resistance calculationConvectionApplication example: Chassis panel cooled by natural convectionRadiationApplication example: Chassis panel cooled only by radiation 7Illustrative example: Simple thermal network model for a heat sinked power transistorIllustrative example: Thermal network circuit for a printed circuit boardCompact component modelsIllustrative example: Pressure and thermal circuits for a forced air cooled enclosureIllustrative example: A single chip package on a printed circuit board-the proble

  8. Radiation induced erosion of autoelectron emitter surface

    CERN Document Server

    Mazilova, T I; Ksenofontov, V A

    2001-01-01

    The peculiarities of erosion of the needle-shaped autoemitter surface under the effect of the helium ions bombardment are studied. The analysis of the radiation-induced formation of the surface atomic roughness testifies to the nondynamic character of shifting the surface atoms by the ions energies below the threshold of the Frenkel stable pairs formation and cathode sputtering. The quasistatic mechanism of the surface erosion due to the atoms shift into the low-coordination positions by releasing the energy of the helium internodal atoms formation is discussed

  9. Evaluation of surface energy and radiation balance systems for FIFE

    Science.gov (United States)

    Fritschen, Leo J.; Qian, Ping

    1988-01-01

    The energy balance and radiation balance components were determined at six sites during the First International Satellite Land Surface Climatology Project Field Experiment (FIFE) conducted south of Manhattan, Kansas during the summer of 1987. The objectives were: to determine the effect of slope and aspect, throughout a growing season, on the magnitude of the surface energy balance fluxes as determined by the Energy Balance Method (EBM); to investigate the calculation of the soil heat flux density at the surface as calculated from the heat capacity and the thermal conductivity equations; and to evaluate the performance of the Surface Energy and Radiation Balance System (SERBS). A total of 17 variables were monitored at each site. They included net, solar (up and down), total hemispherical (up and down), and diffuse radiation, soil temperature and heat flux density, air and wet bulb temperature gradients, wind speed and direction, and precipitation. A preliminary analysis of the data, for the season, indicate that variables including net radiation, air temperature, vapor pressure, and wind speed were quite similar at the sites even though the sites were as much as 16 km apart and represented four cardinal slopes and the top of a ridge.

  10. Development of a test device to characterize thermal protective performance of fabrics against hot steam and thermal radiation

    Science.gov (United States)

    Su, Yun; Li, Jun

    2016-12-01

    Steam burns severely threaten the life of firefighters in the course of their fire-ground activities. The aim of this paper was to characterize thermal protective performance of flame-retardant fabrics exposed to hot steam and low-level thermal radiation. An improved testing apparatus based on ASTM F2731-11 was developed in order to simulate the routine fire-ground conditions by controlling steam pressure, flow rate and temperature of steam box. The thermal protective performance of single-layer and multi-layer fabric system with/without an air gap was studied based on the calibrated tester. It was indicated that the new testing apparatus effectively evaluated thermal properties of fabric in hot steam and thermal radiation. Hot steam significantly exacerbated the skin burn injuries while the condensed water on the skin’s surface contributed to cool down the skin tissues during the cooling. Also, the absorbed thermal energy during the exposure and the cooling was mainly determined by the fabric’s configuration, the air gap size, the exposure time and the existence of hot steam. The research provides a effective method to characterize the thermal protection of fabric in complex conditions, which will help in optimization of thermal protection performance of clothing and reduction of steam burn.

  11. Heat Transfer Issues in Thin-Film Thermal Radiation Detectors

    Science.gov (United States)

    Barry, Mamadou Y.

    1999-01-01

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

  12. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  13. Radiative properties of materials with surface scattering or volume scattering: A review

    Institute of Scientific and Technical Information of China (English)

    Qunzhi ZHU; Hyunjin LEE; Zhuomin M. ZHANG

    2009-01-01

    Radiative properties of rough surfaces, parti-culate media and porous materials are important in thermal engineering and many other applications. These properties are often needed for calculating heat transfer between surfaces and volume elements in participating media, as well as for accurate radiometric temperature measure-ments. In this paper, recent research on scattering of thermal radiation by rough surfaces, fibrous insulation, soot, aerogel, biological materials, and polytetrafluor-oethylene (PTFE) is reviewed. Both theoretical modeling and experimental investigation are discussed. Rigorous solutions and approximation methods for surface scattering and volume scattering are described. The approach of using measured surface roughness statistics in Monte Carlo simulations to predict radiative properties of rough surfaces is emphasized. The effects of various parameters on the radiative properties of particulate media and porous materials are summarized.

  14. Thermal Stability and Vertical Structure of Radiation Dominated Accretion Disks

    Science.gov (United States)

    Jiang, Yanfei; Stone, J. M.; Davis, S.

    2013-01-01

    Standard thin disk model predicts that radiation dominated accretion disk is thermally unstable. However, using a radiation MHD code based on flux-limited diffusion (FLD) approximation, Hirose et al. (2009) finds that when the accretion stress provided by Magneto-rotational instability (MRI) is calculated self-consistently, the disk is actually stable. We check this surprising result with our recently developed radiation transfer module in Athena. We modify the Godunov method to include the radiation source terms and close the radiation momentum equations with variable Eddington tensor. In this way, it works in both optically thin and thick regimes, and works for both radiation or gas pressure dominated flows. As a general purpose radiation MHD code, it can also be used to study other systems, where radiation field plays an important role, such as feedback effects of stars on the interstellar medium. I will show a set of tests to demonstrate that the code is working accurately as expected for different regimes. I will describe in detail our results on the thermal stability of accretion disks in both the gas pressure dominated regime and radiation pressure dominated regime. Detailed studies of the vertical structures of the accretion disk will also be presented. I will also comment on the differences between our results and the results from FLD calculations.

  15. Living Organisms Coupling to Electromagnetic Radiation Below Thermal Noise

    Science.gov (United States)

    Stolc, Viktor; Freund, Friedemann

    2013-04-01

    Ultralow frequency (ULF) and extremely low frequency (ELF) electromagnetic (EM) radiation is part of the natural environment. Prior to major earthquakes the local ULF and global ELF radiation field is often markedly perturbed. This has detrimental effects on living organisms. We are studying the mechanism of these effects on the biochemical, cellular and organismal levels. The transfer of electrons along the Electron Transfer Chain (ETC) controls the universal reduction-oxidation reactions that are essential for fundamental biochemical processes in living cells. In order for these processes to work properly, the ETC has to maintain some form of synchronization, or coherence with all biochemical reactions in the living cells, including energy production, RNA transcription, and DNA replication. As a consequence of this synchronization, harmful chemical conflict between the reductive and the oxidative partial reactions can be minimized or avoided. At the same time we note that the synchronization allows for a transfer of energy, coherent or interfering, via coupling to the natural ambient EM field. Extremely weak high frequency EM fields, well below the thermal noise level, tuned in frequency to the electron spins of certain steps in the ETC, have already been shown to cause aberrant cell growth and disorientation among plants and animals with respect to the magnetic and gravity vectors. We investigate EM fields over a much wider frequency range, including ULF known to be generated deep in the Earth prior to major earthquakes locally, and ELF known to be fed by lightning discharges, traveling around the globe in the cavity formed between the Earth's surface and the ionosphere. This ULF/ELF radiation can control the timing of the biochemical redox cycle and thereby have a universal effect on physiology of organisms. The timing can even have a detrimental influence, via increased oxidative damage, on the DNA replication, which controls heredity.

  16. Flow of variable thermal conductivity fluid due to inclined stretching cylinder with viscous dissipation and thermal radiation

    Institute of Scientific and Technical Information of China (English)

    T HAYAT; S ASAD; A ALSAEDI

    2014-01-01

    The aim of the present study is to investigate the flow of the Casson fluid by an inclined stretching cylinder. A heat transfer analysis is carried out in the presence of thermal radiation and viscous dissipation effects. The temperature dependent thermal conductivity of the Casson fluid is considered. The relevant equations are first simplified under usual boundary layer assumptions, and then transformed into ordinary differential equations by suitable transformations. The transformed ordinary differential equations are computed for the series solutions of velocity and temperature. A convergence analysis is shown explicitly. Velocity and temperature fields are discussed for different physical parameters by graphs and numerical values. It is found that the velocity decreases with the increase in the angle of inclination while increases with the increase in the mixed convection parameter. The enhancement in the thermal conductivity and radiation effects corresponds to a higher fluid temperature. It is also found that heat transfer is more pronounced in a cylinder when it is compared with a flat plate. The thermal boundary layer thickness increases with the increase in the Eckert number. The radiation and variable thermal conductivity decreases the heat transfer rate at the surface.

  17. Three-dimensional, global, radiative GRMHD simulations of a thermally unstable disc

    Science.gov (United States)

    Mishra, B.; Fragile, P. C.; Johnson, L. C.; Kluźniak, W.

    2016-12-01

    We present results of a set of three-dimensional, general relativistic radiation magnetohydrodynamics simulations of thin accretion discs around a non-rotating black hole to test their thermal stability. We consider two cases, one that is initially radiation-pressure-dominated and expected to be thermally unstable and another that is initially gas-pressure dominated and expected to remain stable. Indeed, we find that cooling dominates over heating in the radiation-pressure-dominated model, causing the disc to collapse vertically on roughly the local cooling time-scale. We also find that heating and cooling within the disc have a different dependence on the mid-plane pressure - a prerequisite of thermal instability. Comparison of our data with the relevant thin-disc thermal equilibrium curve suggests that our disc may be headed for the thermally stable, gas-pressure-dominated branch. However, because the disc collapses to the point that we are no longer able to resolve it, we had to terminate the simulation. On the other hand, the gas-pressure-dominated model, which was run for twice as long as the radiation-pressure-dominated one, remains stable, with heating and cooling roughly in balance. Finally, the radiation-pressure-dominated simulation shows some evidence of viscous instability. The strongest evidence is in plots of surface density, which show the disc breaking up into rings.

  18. Accelerated thermal and radiative ageing of hydrogenated NBR for DRC

    Energy Technology Data Exchange (ETDEWEB)

    Mares, G. [EUROTEST S.A., Bucharest (Romania). Research, Equipment Testing, Industrial Engineering and Scientific Services; Notingher, P. [Univ. Politehnica, Bucharest (Romania). Faculty of Electrical Engineering

    1996-12-31

    The accelerated thermal and gamma radiation ageing of HNBR carbon black-T80 has been studied by measuring the residual deformation under constant deflection -- DRC, in air, using a relevant equation for the relaxation phenomena. The residual deformation under constant deflection during the process of accelerated ageing is increasing but the structure of polymer answers in the proper manner to the mechanical stress. The degradation equations were obtained, using Alfrey model for the relaxation polymer subject to compression and an Arrhenius dependence for the chemical reaction rate. The inverted relaxation time for the thermal degradation is depending on the chemical reaction rate and the dose rate of gamma radiation.

  19. Polylogarithmic representation of radiative and thermodynamic properties of thermal radiation in a given spectral range: II. Real-body radiation

    CERN Document Server

    Fisenko, Anatoliy I

    2015-01-01

    The general analytical expressions for the thermal radiative and thermodynamic properties of a real-body are obtained in a finite range of frequencies at different temperatures. The frequency dependence of the spectral emissivity is represented as a power series. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and total emissivity are expressed in terms of the polylogarithm functions. The general expressions for the thermal radiative and thermodynamic functions are applied for the study of thermal radiation of liquid and solid zirconium carbide. These functions are calculated using experimental data for the frequency dependence of the normal spectral emissivity in the visible-near infrared range at the melting (freezing) point. The gaps between the thermal radiative and thermodynamic functions of liquid and solid zirconium carbide are observed. The g...

  20. Response of nickel surface to pulsed fusion plasma radiations

    Science.gov (United States)

    Niranjan, Ram; Rout, R. K.; Srivastava, R.; Chakravarthy, Y.; Patel, N. N.; Alex, P.; Gupta, Satish C.

    2014-04-01

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  1. Thermal Stability Analysis for a Heliocentric Gravitational Radiation Detection Mission

    Science.gov (United States)

    Folkner, W.; McElroy, P.; Miyake, R.; Bender, P.; Stebbins, R.; Supper, W.

    1994-01-01

    The Laser Interferometer Space Antenna (LISA) mission is designed for detailed studies of low-frequency gravitational radiation. The mission is currently a candidate for ESA's post-Horizon 2000 program. Thermal noise affects the measurement in at least two ways. Thermal variation of the length of the optical cavity to which the lasers are stabilized introduces phase variations in the interferometer signal, which have to be corrected for by using data from the two arms separately.

  2. Thermal and radiation resistance of stabilized LDPE

    Energy Technology Data Exchange (ETDEWEB)

    Zaharescu, T., E-mail: traian_zaharescu@yahoo.co [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Jipa, S. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); ' Valahia' University of Targoviste, Faculty of Sciences, Targoviste 130024 (Romania); Henderson, D. [Trinity College, Hartford, CT 06106 (United States); Kappel, W. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Maris, D.A.; Maris, M. [' Ovidius' University, 7 Ilarie Voronca St, P.O. Box 8700, Constanta (Romania)

    2010-03-15

    The effect of capsaicin on the radiation stability of low density polyethylene was accomplished by applying the chemiluminescence procedure. The neat and modified polymer with 0.25% and 0.50% (w/w) capsaicin were exposed to gamma-irradiation in air receiving 10, 20 and 30 kGy. The synergistic effect due to the presence of metallic selenium was demonstrated. The significant improvement in oxidation induction time was obtained demonstrating the efficient antioxidant activity of capsaicin in LDPE. The simultaneous protection action of metallic selenium in LDPE/capsaicin systems brought about a supplementary enhancement in the oxidation resistance of irradiated samples.

  3. Thermal Degradation of Lead Monoxide Filled Polymer Composite Radiation Shields

    Science.gov (United States)

    Harish, V.; Nagaiah, N.

    2011-07-01

    Lead monoxide filled Isophthalate resin particulate polymer composites were prepared with different filler concentrations and investigated for physical, thermal, mechanical and gamma radiation shielding characteristics. This paper discusses about the thermo gravimetric analysis of the composites done to understand their thermal properties especially the effect of filler concentration on the thermal stability & degradation rate of composites. Pristine polymer exhibits single stage degradation whereas filled composites exhibit two stage degradation processes. Further, the IDT values as well as degradation rates decrease with the increased filler content in the composite.

  4. A Study on the Interaction Mechanism between Thermal Radiation and Materials

    Institute of Scientific and Technical Information of China (English)

    Dehong XIA; Tao YU; Chuangu WU; Qingqing CHANG; Honglei JIAO

    2005-01-01

    From the viewpoint of field synergy principle and dipole radiation theory, the interaction between the incident thermal radiation wave and materials is analyzed to reveal the mechanism of selective absorption of incident thermal radiation. It is shown that the frequency of the incident thermal radiation and the damping constant of damping oscillators in materials are of vital importance for the thermal radiation properties (reflectivity, absorptivity, transmissivity, etc.) of materials.

  5. Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

    Institute of Scientific and Technical Information of China (English)

    杜文峰; 胡文瑞

    2003-01-01

    For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere of O2-N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere of O2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

  6. Thermal characterization of nanoporous 'black silicon' surfaces

    Science.gov (United States)

    Nichols, Logan; Duan, Wenqi; Toor, Fatima

    2016-09-01

    In this work we characterize the thermal conductivity properties of nanoprous `black silicon' (bSi). We fabricate the nanoporous bSi using the metal assisted chemical etching (MACE) process utilizing silver (Ag) metal as the etch catalyst. The MACE process steps include (i) electroless deposition of Ag nanoparticles on the Si surface using silver nitrate (AgNO3) and hydrofluoric acid (HF), and (ii) a wet etch in a solution of HF and hydrogen peroxide (H2O2). The resulting porosity of bSi is dependent on the ratio of the concentration of HF to (HF + H2O2); the ratio is denoted as rho (ρ). We find that as etch time of bSi increases the thermal conductivity of Si increases as well. We also analyze the absorption of the bSi samples by measuring the transmission and reflection using IR spectroscopy. This study enables improved understanding of nanoporous bSi surfaces and how they affect the solar cell performance due to the porous structures' thermal properties.

  7. Directional Characteristics of Thermal-Infrared Beaming from Atmosphereless Planetary Surfaces - A New Thermophysical Model

    CERN Document Server

    Rozitis, Ben

    2012-01-01

    We present a new rough-surface thermophysical model (Advanced Thermophysical Model or ATPM) that describes the observed directional thermal emission from any atmosphereless planetary surface. It explicitly incorporates partial shadowing, scattering of sunlight, selfheating and thermal-infrared beaming (re-radiation of absorbed sunlight back towards the Sun as a result of surface roughness). The model is verified by accurately reproducing ground-based directional thermal emission measurements of the lunar surface using surface properties that are consistent with the findings of the Apollo missions and roughness characterised by an RMS slope of ~32 degrees. By considering the wide range of potential asteroid surface properties, the model implies a beaming effect that cannot be described by a simple parameter or function. It is highly dependent on the illumination and viewing angles as well as surface thermal properties and is predominantly caused by macroscopic rather than microscopic roughness. Roughness alter...

  8. Thermal stability of radiating fluids: The scattering problem

    Science.gov (United States)

    Bakan, Stephan

    1984-12-01

    The problem of convective instability of a radiating fluid layer with scattering is treated with an extension of the Eddington aproximation that allows the inclusion of anisotropic scattering into the solution of the radiative transfer equation. Introduction of scattering by keeping the optical depth of absorption constant reduces the critical Rayleigh number as well as the wavenumber, and thus, reduces the stabilizing influence of thermal radiation. It is shown that in cases of a narrow radiative boundary layer with a large temperature gradient, higher-order expansion terms are sometimes necessary to approximate the solution properly. In certain cases a two layer convection mode with a large critical wavenumber up to 50 sets in the first layer has two cells developing in and near the two radiative boundary layers.

  9. Normalization Of Thermal-Radiation Form-Factor Matrix

    Science.gov (United States)

    Tsuyuki, Glenn T.

    1994-01-01

    Report describes algorithm that adjusts form-factor matrix in TRASYS computer program, which calculates intraspacecraft radiative interchange among various surfaces and environmental heat loading from sources such as sun.

  10. Thermal scale modeling of radiation-conduction-convection systems.

    Science.gov (United States)

    Shannon, R. L.

    1972-01-01

    Investigation of thermal scale modeling applied to radiation-conduction-convection systems with particular emphasis on the spacecraft cabin atmosphere/cabin wall thermal interface. The 'modified material preservation,' 'temperature preservation,' 'scaling compromises,' and 'Nusselt number preservation' scale modeling techniques and their inherent limitations and problem areas are described. The compromised scaling techniques of mass flux preservation and heat transfer coefficient preservation show promise of giving adequate thermal similitude while preserving both gas and temperature in the scale model. The use of these compromised scaling techniques was experimentally demonstrated in tests of full scale and 1/4 scale models. Correlation of test results for free and forced convection under various test conditions shows the effectiveness of these scaling techniques. It is concluded that either mass flux or heat transfer coefficient preservation may result in adequate thermal similitude depending on the system to be modeled. Heat transfer coefficient preservation should give good thermal similitude for manned spacecraft scale modeling applications.

  11. Thermal radiation field of low-temperature sources

    Science.gov (United States)

    Łakomy, T.

    1989-05-01

    The asymmetric thermal radiation field of heat sources existing in industry and in the building of apartments has been determined in this work. A description was realised by vector radiant and mean radiant temperatures ( VRT, TMR) obtaining their statistic reciprocal relationships at summer and winter terms.

  12. Thermally radiative three-dimensional flow of Jeffrey nanofluid with internal heat generation and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Shehzad, S.A., E-mail: ali_qau70@yahoo.com [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Abdullah, Z. [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Abbasi, F.M. [Department of Mathematics, Comsats Institute of Information Technology, Islamabad 44000 (Pakistan); Hayat, T. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan)

    2016-01-01

    This research work addresses the three-dimensional hydromagnetic flow of Jeffrey fluid with nanoparticles. Flow is generated by a bidirectional stretching surface. The effects of thermal radiation and internal heat generation are encountered in energy expressions. More realistic convective boundary conditions at the surface are employed instead of constant surface temperature and mass species conditions. Boundary layer assumptions lead to the governing non-linear mathematical model. Resulting equations through momentum, energy and mass species are made dimensionless using suitable variables. The solution expressions of dimensionless velocities, temperature and nanoparticle concentration have been computed for the convergent series solutions. The impacts of interesting parameters on the dimensionless quantities are displayed and interpreted. The values of physical quantities are computed and analyzed. - Highlights: • Three-dimensional hydromagnetic flow of Jeffrey nanofluid is considered. • Brownian motion and thermophoresis effects are encountered. • Heat transfer analysis is performed with thermal radiation. • Results are plotted and visualized.

  13. Thermal Vacuum Test of Ice as a Phase Change Material Integrated with a Radiator

    Science.gov (United States)

    Lee, Steve A.; Leimkuehler, Thomas O.; Stephan, Ryan; Le, Hung V.

    2010-01-01

    Water may be used as radiation shielding for Solar Particle Events (SPE) to protect crewmembers in the Lunar Electric Rover (LER). Because the water is already present for radiation protection, it could also provide a mass efficient solution to the vehicle's thermal control system. This water can be frozen by heat rejection from a radiator and used as a Phase Change Material (PC1V1) for thermal storage. Use of this water as a PCM can eliminate the need for a pumped fluid loop thermal control system as well as reduce the required size of the radiator. This paper describes the testing and analysis performed for the Rover Engineering Development Unit (REDU), a scaled-down version of a water PCM heat sink for the LER. The REDU was tested in a thermal-vacuum chamber at environmental temperatures similar to those of a horizontal radiator panel on the lunar surface. Testing included complete freeze and melt cycles along with scaled transient heat load profiles simulating a 24-hour day for the rover.

  14. APPLICATION OF SURFACE GRAFTED POLY N-ISOPROPYL ACRYLAMIDE BY RADIATION TECHNOLOGY FOR PROTEIN SOLUTION CONCENTRATION

    Institute of Scientific and Technical Information of China (English)

    SUN Yishi; LI Huaizhong; LIU Pengfei; HA Hongfei

    1991-01-01

    Poly N-isopropyl acrylamide (abbreviated as PNIPA) as a kind of thermally sensitive hydrogel is utilized to concentrate Bovin Serum Albumin (BSA) solution. In order to decrease its surface adsorption to BSA in aqueous solution, surface layer grafting of the gels by radiation technology was carried out. The results showed that hydroxyl propyl methacrylate (HPMA) grafted gel exhibited a low level of BSA adsorption and still kept the original thermally sensitive properties of PNIPA hydrogels.

  15. Temperature control of thermal radiation from composite bodies

    Science.gov (United States)

    Jin, Weiliang; Polimeridis, Athanasios G.; Rodriguez, Alejandro W.

    2016-03-01

    We demonstrate that recent advances in nanoscale thermal transport and temperature manipulation can be brought to bear on the problem of tailoring thermal radiation from wavelength-scale composite bodies. We show that such objects—complicated arrangements of phase-change chalcogenide (Ge2Sb2Te5 ) glasses and metals or semiconductors—can be designed to exhibit strong resonances and large temperature gradients, which in turn lead to large and highly directional emission at midinfrared wavelengths. We find that partial directivity depends sensitively on a complicated interplay between shape, material dispersion, and temperature localization within the objects, requiring simultaneous design of the electromagnetic scattering and thermal properties of these structures. Our calculations exploit a recently developed fluctuating-volume current formulation of electromagnetic fluctuations that rigorously captures radiation phenomena in structures with strong temperature and dielectric inhomogeneities, such as those studied here.

  16. MHD three-dimensional flow of nanofluid with velocity slip and nonlinear thermal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Tasawar [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Imtiaz, Maria, E-mail: mi_qau@yahoo.com [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Alsaedi, Ahmed; Kutbi, Marwan A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2015-12-15

    An analysis has been carried out for the three dimensional flow of viscous nanofluid in the presence of partial slip and thermal radiation effects. The flow is induced by a permeable stretching surface. Water is treated as a base fluid and alumina as a nanoparticle. Fluid is electrically conducting in the presence of applied magnetic field. Entire different concept of nonlinear thermal radiation is utilized in the heat transfer process. Different from the previous literature, the nonlinear system for temperature distribution is solved and analyzed. Appropriate transformations reduce the nonlinear partial differential system to ordinary differential system. Convergent series solutions are computed for the velocity and temperature. Effects of different parameters on the velocity, temperature, skin friction coefficient and Nusselt number are computed and examined. It is concluded that heat transfer rate increases when temperature and radiation parameters are increased. - Highlights: • Three-dimensional nanofluid flow with partial slip and nonlinear thermal radiation is studied. • Increasing values of velocity slip parameter decrease the velocity profiles. • The temperature increases via larger nanoparticle volume fraction. • Surface temperature gradient increases for higher temperature and radiation parameters.

  17. Nanodiamond formation via thermal radiation from an air shock

    Science.gov (United States)

    de Carli, Paul

    2013-06-01

    Nanodiamonds have recently been found in sediments of Younger Dryas age, about 12,900 years ago. Carbon isotope ratios imply that the source of carbon was terrestrial organic matter and rule out the possibility that the diamond was of cosmic origin, e.g., from an influx of meteorites. The nanodiamonds are associated with mineral spherules (and other shapes) that have compositions and textures consistent with the rapid melting and solidification of local soil. The inferred temperatures are much too high for natural events such as forest fires. Similar deposits of nanodiamond have been found in the 65 million year old K-Pg layer associated with the ca. 200 km diameter Chicxulub impact crater. Nanodiamond have also been reported in the vicinity of the Tunguska event, presumed to be the result of an air shock produced by the interaction of a rapidly moving cosmic body with the Earth's atmosphere. We infer that the nanodiamonds were formed when the thermal radiation from the air shock pyrolyzed surface organic matter. Rapid reaction locally depleted the atmosphere of oxygen and the remaining carbon could condense as nanodiamond. A similar mechanism can be invoked to account for the formation of nanodiamond as a froduct of the detonation of ozygen-deficient high explosives.

  18. Radiative Transport Modelling of Thermal Barrier Coatings

    Science.gov (United States)

    2017-03-24

    traveled by signal and reference beam photons) is the result of signal photons travelling a distance L through the sample . Since this distance L is related...performed in both tasks together for convenience . First, we briefly discuss the random walk model, since it is relevant in the discussion on both the...Figure 7, whereby a collinear low coherence beam (shown as a red arrow) is considered to be incident onto the sample at normal incidence to the surface

  19. Bioadhesion to model thermally responsive surfaces

    Science.gov (United States)

    Andrzejewski, Brett Paul

    This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG 6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The gold substrates were imaged prior to SAM formation with atomic force micrscopy (AFM). Average surface roughness of the gold substrate was 0.44 nm, 0.67 nm, 1.65 nm for 15, 25 and 60 nm gold thickness, respectively. The height of the mixed SAM was measured by ellipsometry and varied from 13 to 28°A depending on surface mole fraction of C11EG6OH. The surface mole fraction of C11EG6OH for the mixed SAM was determined by X-ray photoelectron spectroscopy (XPS) with optimal thermal responsive behavior in the range of 0.4 to 0.6. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28°C and ˜55° at 40°C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal responsive of the mixed SAM are discussed. Lastly, rat fibroblasts were grown on the mixed SAM and imaged by phase contrast microscopy to show inhibition of attachment at temperatures below the molecular transition. Qualitative and quantitative measurements of the fibroblast adhesion data are provided that support the hypothesis of the mixed SAM exhibits a dominantly non-fouling molecular conformation at 25°C whereas it exhibits a dominantly fouling molecular conformation at 40°C. The adhesion of six model proteins: bovine serum albumin, collagen, pyruvate kinase, cholera toxin subunit B, ribonuclease, and lysozyme to the model thermally responsive mixed SAM were examined using AFM. All six proteins possessed adhesion to the pure component alkyl thiol, in

  20. Atmospheres and radiating surfaces of neutron stars with strong magnetic fields

    CERN Document Server

    Potekhin, A Y; Chabrier, G

    2016-01-01

    We review the current status of the theory of thermal emission from the surface layers of neutron stars with strong magnetic fields $B\\sim 10^{10}-10^{15}$ G, including formation of the spectrum in a partially ionized atmosphere and at a condensed surface. In particular, we describe recent progress in modeling partially ionized atmospheres of central compact objects in supernova remnants, which may have moderately strong fields $B\\sim 10^{10}-10^{11}$ G. Special attention is given to polarization of thermal radiation emitted by a neutron star surface. Finally, we briefly describe applications of the theory to observations of thermally emitting isolated neutron stars.

  1. Degradation of thermal control materials under a simulated radiative space environment

    Science.gov (United States)

    Sharma, A. K.; Sridhara, N.

    2012-11-01

    A spacecraft with a passive thermal control system utilizes various thermal control materials to maintain temperatures within safe operating limits. Materials used for spacecraft applications are exposed to harsh space environments such as ultraviolet (UV) and particle (electron, proton) irradiation and atomic oxygen (AO), undergo physical damage and thermal degradation, which must be considered for spacecraft thermal design optimization and cost effectiveness. This paper describes the effect of synergistic radiation on some of the important thermal control materials to verify the assumptions of beginning-of-life (BOL) and end-of-life (EOL) properties. Studies on the degradation in the optical properties (solar absorptance and infrared emittance) of some important thermal control materials exposed to simulated radiative geostationary space environment are discussed. The current studies are purely related to the influence of radiation on the degradation of the materials; other environmental aspects (e.g., thermal cycling) are not discussed. The thermal control materials investigated herein include different kind of second-surface mirrors, white anodizing, white paints, black paints, multilayer insulation materials, varnish coated aluminized polyimide, germanium coated polyimide, polyether ether ketone (PEEK) and poly tetra fluoro ethylene (PTFE). For this purpose, a test in the constant vacuum was performed reproducing a three year radiative space environment exposure, including ultraviolet and charged particle effects on North/South panels of a geostationary three-axis stabilized spacecraft. Reflectance spectra were measured in situ in the solar range (250-2500 nm) and the corresponding solar absorptance values were calculated. The test methodology and the degradations of the materials are discussed. The most important degradations among the low solar absorptance materials were found in the white paints whereas the rigid optical solar reflectors remained quite

  2. The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings: Models and Experiments

    Science.gov (United States)

    Zhu, Dongming; Spuckler, Charles M.

    2010-01-01

    The lattice and radiation conductivity of ZrO2-Y2O3 thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the coating apparent thermal conductivity to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature, coating material scattering, and absorption properties. High temperature scattering and absorption of the coating systems can be also derived based on the testing results using the modeling approach. A comparison has been made for the gray and nongray coating models in the plasma-sprayed thermal barrier coatings. The model prediction is found to have a good agreement with experimental observations.

  3. Transient radiative heat transfer in an inhomogeneous participating medium with Fresnel’s surfaces

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper studies the radiative heat transfer within an inhomogeneous and isot- ropically scattering medium with reflecting Fresnel’s surfaces. Thermal radiation transfers in a curve inside a medium with an inhomogeneous distribution of a re- fractive index. The inhomogenous medium is divided into n homogenous isother- mal sub-layers and in each sub-layer the radiation transfers in a straight line. By adopting a multilayer radiative transfer model and using a ray-tracing/nodal- ana- lyzing method, a radiative transfer model is built for the inhomogenous participat- ing medium. In the multilayer model, a criterion for refraction / total reflection at the interfaces between neighboring sub-layers is introduced, avoiding the integral singularity and reflection at physically inexistent interfaces (only the total reflection is considered). Transient thermal behavior is examined when the parameters of the radiative properties such as refractive indexes, extinction coefficients, and sin- gle-scattering albedoes vary continually along the thickness direction.

  4. The influence of surface type on the absorbed radiation by a human under hot, dry conditions

    Science.gov (United States)

    Hardin, A. W.; Vanos, J. K.

    2017-05-01

    Given the predominant use of heat-retaining materials in urban areas, numerous studies have addressed the urban heat island mitigation potential of various "cool" options, such as vegetation and high-albedo surfaces. The influence of altered radiational properties of such surfaces affects not only the air temperature within a microclimate, but more importantly the interactions of long- and short-wave radiation fluxes with the human body. Minimal studies have assessed how cool surfaces affect thermal comfort via changes in absorbed radiation by a human (R abs) using real-world, rather than modeled, urban field data. The purpose of the current study is to assess the changes in the absorbed radiation by a human—a critical component of human energy budget models—based on surface type on hot summer days (air temperatures > 38.5∘C). Field tests were conducted using a high-end microclimate station under predominantly clear sky conditions over ten surfaces with higher sky view factors in Lubbock, Texas. Three methods were used to measure and estimate R abs: a cylindrical radiation thermometer (CRT), a net radiometer, and a theoretical estimation model. Results over dry surfaces suggest that the use of high-albedo surfaces to reduce overall urban heat gain may not improve acute human thermal comfort in clear conditions due to increased reflected radiation. Further, the use of low-cost instrumentation, such as the CRT, shows potential in quantifying radiative heat loads within urban areas at temporal scales of 5-10 min or greater, yet further research is needed. Fine-scale radiative information in urban areas can aid in the decision-making process for urban heat mitigation using non-vegetated urban surfaces, with surface type choice is dependent on the need for short-term thermal comfort, or reducing cumulative heat gain to the urban fabric.

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

    Science.gov (United States)

    Page, Arthur T.

    2001-07-01

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

  6. Polylogarithmic Representation of Radiative and Thermodynamic Properties of Thermal Radiation in a Given Spectral Range: II. Real-Body Radiation

    Science.gov (United States)

    Fisenko, Anatoliy I.; Lemberg, Vladimir

    2015-11-01

    There are several classes of materials and space objects for which the frequency dependence of the spectral emissivity is represented as a power series. Therefore, the study of the properties of thermal radiation for these real bodies is an important task for both fundamental science and industrial applications. The general analytical expressions for the thermal radiative and thermodynamic functions of a real body are obtained in a finite range of frequencies at different temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and total emissivity are expressed in terms of the polylogarithm functions. The obtained general expressions for the thermal radiative and thermodynamic functions are applied for the study of thermal radiation of liquid and solid zirconium carbide. These functions are calculated using experimental data for the frequency dependence of the normal spectral emissivity in the visible and near-infrared range at the melting (freezing) point. The gaps between the thermal radiative and thermodynamic functions of liquid and solid zirconium carbide are observed. The general analytical expressions obtained can easily be presented in the wavenumber domain.

  7. MHD three-dimensional flow of nanofluid with velocity slip and nonlinear thermal radiation

    Science.gov (United States)

    Hayat, Tasawar; Imtiaz, Maria; Alsaedi, Ahmed; Kutbi, Marwan A.

    2015-12-01

    An analysis has been carried out for the three dimensional flow of viscous nanofluid in the presence of partial slip and thermal radiation effects. The flow is induced by a permeable stretching surface. Water is treated as a base fluid and alumina as a nanoparticle. Fluid is electrically conducting in the presence of applied magnetic field. Entire different concept of nonlinear thermal radiation is utilized in the heat transfer process. Different from the previous literature, the nonlinear system for temperature distribution is solved and analyzed. Appropriate transformations reduce the nonlinear partial differential system to ordinary differential system. Convergent series solutions are computed for the velocity and temperature. Effects of different parameters on the velocity, temperature, skin friction coefficient and Nusselt number are computed and examined. It is concluded that heat transfer rate increases when temperature and radiation parameters are increased.

  8. Methane Lunar Surface Thermal Control Test

    Science.gov (United States)

    Plachta, David W.; Sutherlin, Steven G.; Johnson, Wesley L.; Feller, Jeffrey R.; Jurns, John M.

    2012-01-01

    NASA is considering propulsion system concepts for future missions including human return to the lunar surface. Studies have identified cryogenic methane (LCH4) and oxygen (LO2) as a desirable propellant combination for the lunar surface ascent propulsion system, and they point to a surface stay requirement of 180 days. To meet this requirement, a test article was prepared with state-of-the-art insulation and tested in simulated lunar mission environments at NASA GRC. The primary goals were to validate design and models of the key thermal control technologies to store unvented methane for long durations, with a low-density high-performing Multi-layer Insulation (MLI) system to protect the propellant tanks from the environmental heat of low Earth orbit (LEO), Earth to Moon transit, lunar surface, and with the LCH4 initially densified. The data and accompanying analysis shows this storage design would have fallen well short of the unvented 180 day storage requirement, due to the MLI density being much higher than intended, its substructure collapse, and blanket separation during depressurization. Despite the performance issue, insight into analytical models and MLI construction was gained. Such modeling is important for the effective design of flight vehicle concepts, such as in-space cryogenic depots or in-space cryogenic propulsion stages.

  9. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    王锦地; 李小文; 孙晓敏; 刘强

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface, its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel. In this paper, we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel’s component parameters, and invert the model to get the component temperatures. For the inversion algorithm, we focus on how to use the information of given observations in a more effective way. The information content in data space and parameter space is defined, and the transferring of information content in inversion procedure is studied. Our forward model and inversion method are validated using indoor directional measurement data.

  10. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface,its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel.In this paper,we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel's component parameters,and invert the model to get the component temperatures.For the inversion algorithm,we focus on how to use the information of given observations in a more effective way.The information content in data space and parameter space is defined,and the transferring of information content in inversion procedure is studied.Our forward model and inversion method are validated using indoor directional measurement data.

  11. Estimation of Hourly Solar Radiation at the Surface under Cloudless Conditions on the Tibetan Plateau Using a Simple Radiation Model

    Institute of Scientific and Technical Information of China (English)

    LIANG Hong; ZHANG Renhe; LIU Jingmiao; SUN Zhian; CHENG Xinghong

    2012-01-01

    In this study,the clear sky hourly global and net solar irradiances at the surface determined using SUNFLUX,a simple parameterization scheme,for three stations (Gaize,Naqu,and Lhasa) on the Tibetan Plateau were evaluated against observation data.Our modeled results agree well with observations.The correlation coefficients between modeled and observed values were >0.99 for all three stations.The relative error of modeled results,in average was < 7%,and the root-mean-square variance was < 27 W m-2.The solar irradiances in the radiation model were slightly overestimated compared with observation data;there were at least two likely causes.First,the radiative effects of aerosols were not included in the radiation model.Second,solar irradiances determined by thermopile pyranometers include a thermal offset error that causes solar radiation to be slightly underestimated.The solar radiation absorbed by the ozone and water vapor was estimated. The results show that monthly mean solar radiation absorbed by the ozone is < 2% of the global solar radiation (< 14 W m-2).Solar radiation absorbed by water vapor is stronger in summer than in winter.The maximum amount of monthly mean solar radiation absorbed by water vapor can be up to 13% of the global solar radiation (95W m-2).This indicates that water vapor measurements with high precision are very important for precise determination of solar radiation.

  12. Investigation of gold as a material for thermal radiation shielding

    Science.gov (United States)

    Munshi, Amit Harenkumar

    CdS/CdTe thin film solar cells technology is one of the fastest growing carbon neutral energy sources in the world today. Manufacturing of CdS/CdTe solar modules is carried out at temperature in the range of 620350°C under a vacuum of 40 millitorr using a Heated Pocket Deposition (HPD) system in the materials engineering laboratory. Since this system operates in vacuum, majority of the heat loss is due to thermal radiation. The concept here is to conserve the heat by reflecting the infrared radiation back into the deposition system thus increasing the thermal efficiency. Various metals may be used but calculations show that using a Gold thin film mirror can effectively reflect almost 97% of the incident radiation, thus conserving energy required for the manufacturing process. However, a phenomenon called thermal grooving or island formation inhibits its use. Thermal grooving occurs when the stress concentration at the grain boundaries causes grain separation. This phenomenon is observed in thin gold films that are exposed to a temperature in excess of 350°C for over 3 to 5 hours. In this study, these films are exposed to temperature upto 620350°C for cycles as long as 200 hours. The goal of this research is to explore the solutions for elimination of the phenomenon of thermal grooving and thus extract maximum life out of these thin gold films for conservation of heat. After carefully exploring literature on past research and conducting experiments it was found that within the range of the films that were tested, a 2000 A350° film with a 150 A350° of Indium underlay showed the best performance after thermal annealing and testing.

  13. Non-Thermal Electromagnetic Radiation Damage to Lens Epithelium

    OpenAIRE

    Bormusov, Elvira; P.Andley, Usha; Sharon, Naomi; Schächter, Levi; Lahav, Assaf; Dovrat, Ahuva

    2008-01-01

    High frequency microwave electromagnetic radiation from mobile phones and other modern devices has the potential to damage eye tissues, but its effect on the lens epithelium is unknown at present. The objective of this study was to investigate the non-thermal effects of high frequency microwave electromagnetic radiation (1.1GHz, 2.22 mW) on the eye lens epithelium in situ. Bovine lenses were incubated in organ culture at 35°C for 10-15 days. A novel computer-controlled microwave source was us...

  14. Thermal Radio Emission from Radiative Shocks in Colliding Stellar Winds

    Science.gov (United States)

    Montes, Gabriela; González, Ricardo F.; Cantó, Jorge; Pérez-Torres, Miguel A.; Alberdi, Antonio

    2011-01-01

    We present a semi-analytic model for computing the thermal radio continuum emission from radiative shocks within colliding wind binaries. Assuming a thin shell approximation, we determine the contribution of the wind collision region (WCR) to the total thermal emission for close binaries. We investigate the effect of the binary separation and the stellar wind parameters on the total spectrum. In addition, we point out the relevance of taking into account this contribution for the correct interpretation of the observations, and the accuracy of the stellar wind parameters derived from them.

  15. Thermal Radio Emission from Radiative Shocks in Colliding Wind Binaries

    Science.gov (United States)

    Montes, G.; González, R. F.; Cantó, J.; Pérez-Torres, M. A.; Alberdi, A.

    2011-10-01

    We present a semi-analytic model for computing the thermal radio continuum emission from radiative shocks within colliding wind binaries. Assuming a thin shell approximation, we calculate the contribution of the wind collision region (WCR) to the total thermal emission for close binaries. We investigate the effect of the binary separation on the total spectrum. In addition, we point out the relevance of taking into account this contribution for the correct interpretation of the observations, and the accuracy of parameters derived from them.

  16. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Science.gov (United States)

    Seguchi, Tadao; Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko; Kudoh, Hisaaki

    2011-02-01

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 °C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  17. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Seguchi, Tadao, E-mail: seguchi@aj.wakwak.co [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Kudoh, Hisaaki [University of Tokyo, Tokai 319-1195 (Japan)

    2011-02-15

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 {sup o}C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  18. A Morphing Radiator for High-Turndown Thermal Control of Crewed Space Exploration Vehicles

    Science.gov (United States)

    Cognata, Thomas J.; Hardtl, Darren; Sheth, Rubik; Dinsmore, Craig

    2015-01-01

    Spacecraft designed for missions beyond low earth orbit (LEO) face a difficult thermal control challenge, particularly in the case of crewed vehicles where the thermal control system (TCS) must maintain a relatively constant internal environment temperature despite a vastly varying external thermal environment and despite heat rejection needs that are contrary to the potential of the environment. A thermal control system is in other words required to reject a higher heat load to warm environments and a lower heat load to cold environments, necessitating a quite high turndown ratio. A modern thermal control system is capable of a turndown ratio of on the order of 12:1, but for crew safety and environment compatibility these are massive multi-loop fluid systems. This paper discusses the analysis of a unique radiator design which employs the behavior of shape memory alloys (SMA) to vary the turndown of, and thus enable, a single-loop vehicle thermal control system for space exploration vehicles. This design, a morphing radiator, varies its shape in response to facesheet temperature to control view of space and primary surface emissivity. Because temperature dependence is inherent to SMA behavior, the design requires no accommodation for control, instrumentation, nor power supply in order to operate. Thermal and radiation modeling of the morphing radiator predict a turndown ranging from 11.9:1 to 35:1 independent of TCS configuration. Stress and deformation analyses predict the desired morphing behavior of the concept. A system level mass analysis shows that by enabling a single loop architecture this design could reduce the TCS mass by between 139 kg and 225 kg. The concept is demonstrated in proof-of-concept benchtop tests.

  19. Decoherence of matter waves by thermal emission of radiation

    CERN Document Server

    Hackermüller, L; Brezger, B; Zeilinger, Anton; Arndt, M; Hackermueller, Lucia; Hornberger, Klaus; Brezger, Bjoern; Zeilinger, Anton; Arndt, Markus

    2004-01-01

    Emergent quantum technologies have led to increasing interest in decoherence - the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory has been complemented by experiments using matter waves coupled to external photons or molecules, and by investigations using coherent photon states, trapped ions and electron interferometers. Large molecules are particularly suitable for the investigation of the quantum-classical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find...

  20. Thermal performance of a porus radial fin with natural convection and radiative heat losses

    Directory of Open Access Journals (Sweden)

    Darvishi M.T.

    2015-01-01

    Full Text Available An analytic (series solution is developed to describe the thermal performance of a porous radial fin with natural convection in the fluid saturating the fin and radiation heat loss from the top and bottom surfaces of the fin. The HAM results for the temperature distribution and base heat flux are compared with the direct numerical results and found to be very accurate.

  1. Autonomous Aerobraking Using Thermal Response Surface Analysis

    Science.gov (United States)

    Prince, Jill L.; Dec, John A.; Tolson, Robert H.

    2007-01-01

    Aerobraking is a proven method of significantly increasing the science payload that can be placed into low Mars orbits when compared to an all propulsive capture. However, the aerobraking phase is long and has mission cost and risk implications. The main cost benefit is that aerobraking permits the use of a smaller and cheaper launch vehicle, but additional operational costs are incurred during the long aerobraking phase. Risk is increased due to the repeated thermal loading of spacecraft components and the multiple attitude and propulsive maneuvers required for successful aerobraking. Both the cost and risk burdens can be significantly reduced by automating the aerobraking operations phase. All of the previous Mars orbiter missions that have utilized aerobraking have increasingly relied on onboard calculations during aerobraking. Even though the temperature of spacecraft components has been the limiting factor, operational methods have relied on using a surrogate variable for mission control. This paper describes several methods, based directly on spacecraft component maximum temperature, for autonomously predicting the subsequent aerobraking orbits and prescribing apoapsis propulsive maneuvers to maintain the spacecraft within specified temperature limits. Specifically, this paper describes the use of thermal response surface analysis in predicting the temperature of the spacecraft components and the corresponding uncertainty in this temperature prediction.

  2. Autonomous Aerobraking: Thermal Analysis and Response Surface Development

    Science.gov (United States)

    Dec, John A.; Thornblom, Mark N.

    2011-01-01

    A high-fidelity thermal model of the Mars Reconnaissance Orbiter was developed for use in an autonomous aerobraking simulation study. Response surface equations were derived from the high-fidelity thermal model and integrated into the autonomous aerobraking simulation software. The high-fidelity thermal model was developed using the Thermal Desktop software and used in all phases of the analysis. The use of Thermal Desktop exclusively, represented a change from previously developed aerobraking thermal analysis methodologies. Comparisons were made between the Thermal Desktop solutions and those developed for the previous aerobraking thermal analyses performed on the Mars Reconnaissance Orbiter during aerobraking operations. A variable sensitivity screening study was performed to reduce the number of variables carried in the response surface equations. Thermal analysis and response surface equation development were performed for autonomous aerobraking missions at Mars and Venus.

  3. Thermal instability of DLC film surface morphology - an AFM study

    Science.gov (United States)

    Maheswaran, R.; Thiruvadigal, D. John; Gopalakrishnan, C.

    2012-06-01

    The surface morphology of the DLC film during thermal annealing at particular temperature above the graphitization temperature shows blistering and buckling and also delaminates from the substrate. The DLC film shows poor thermal stability at higher temperature.

  4. Decoherence of matter waves by thermal emission of radiation.

    Science.gov (United States)

    Hackermüller, Lucia; Hornberger, Klaus; Brezger, Björn; Zeilinger, Anton; Arndt, Markus

    2004-02-19

    Emergent quantum technologies have led to increasing interest in decoherence--the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory has been complemented by experiments using matter waves coupled to external photons or molecules, and by investigations using coherent photon states, trapped ions and electron interferometers. Large molecules are particularly suitable for the investigation of the quantum-classical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies.

  5. Harmonics radiation of graphene surface plasmon polaritons in terahertz regime

    Energy Technology Data Exchange (ETDEWEB)

    Li, D., E-mail: dazhi_li@hotmail.com [Institute for Laser Technology, Suita, Osaka 565-0871 (Japan); Wang, Y. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Nakajima, M. [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Hashida, M. [Advanced Research Center for Beam Science, ICR, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Wei, Y. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Miyamoto, S. [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, Ako, Hyogo 678-1205 (Japan)

    2016-06-03

    This letter presents an approach to extract terahertz radiation from surface plasmon polaritons excited in the surface of a uniform graphene structure by an electron beam. A sidewall configuration is proposed to lift the surface plasmon mode to be close to the light line, so that some of its harmonics have chances to go above the light line and become radiative. The harmonics are considered to be excited by a train of periodic electron bunches. The physical mechanism in this scheme is analyzed with three-dimensional theory, and the harmonics excitation and radiation are demonstrated through numerical calculations. The results show that this technique could be an alternative to transform the surface plasmon polaritons into radiation. - Highlights: • An approach to extract terahertz radiation from graphene surface plasmon polaritons is presented. • A sidewall configuration is proposed to lift the surface plasmon mode. • Harmonics of surface plasmon polaritons are possible to radiate.

  6. Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jui-Yung; Basu, Soumyadipta; Yang, Yue; Wang, Liping, E-mail: liping.wang@asu.edu [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

    2016-06-07

    Recently, near-field thermal radiation has attracted much attention in several fields since it can exceed the Planck blackbody limit through the coupling of evanescent waves. In this work, near-field radiative heat transfer between two semi-infinite dual uniaxial electromagnetic metamaterials with two different material property sets is theoretically analyzed. The near-field radiative heat transfer is calculated using fluctuational electrodynamics incorporated with anisotropic wave optics. The underlying mechanisms, namely, magnetic hyperbolic mode, magnetic surface polariton, electrical hyperbolic mode, and electrical surface polariton, between two homogeneous dual uniaxial electromagnetic metamaterials are investigated by examining the transmission coefficient and the spectral heat flux. The effect of vacuum gap distance is also studied, which shows that the enhancement at smaller vacuum gap is mainly due to hyperbolic mode and surface plasmon polariton modes. In addition, the results show that the contribution of s-polarized waves is significant and should not be excluded due to the strong magnetic response regardless of vacuum gap distances. The fundamental understanding and insights obtained here will facilitate the finding and application of novel materials for near-field thermal radiation.

  7. Thermalization via heat radiation of an individual object thinner than the thermal wavelength.

    Science.gov (United States)

    Wuttke, C; Rauschenbeutel, A

    2013-07-12

    Modeling and investigating the thermalization of microscopic objects with arbitrary shape from first principles is of fundamental interest and may lead to technical applications. Here, we study, over a large temperature range, the thermalization dynamics due to far-field heat radiation of an individual, deterministically produced silica fiber with a predetermined shape and a diameter smaller than the thermal wavelength. The temperature change of the subwavelength-diameter fiber is determined through a measurement of its optical path length in conjunction with an ab initio thermodynamic model of the fiber structure. Our results show excellent agreement with a theoretical model that considers heat radiation as a volumetric effect and takes the emitter shape and size relative to the emission wavelength into account.

  8. Evaluation of thermal resistance of building insulations with reflective surfaces

    Science.gov (United States)

    Št'astník, S.

    2012-09-01

    The thermal resistance of advanced insulation materials, applied namely in civil engineering, containing reflective surfaces and air gaps, cannot be evaluated correctly using the valid European standards because of presence of the dominant nonlinear radiative heat transfer and other phenomena not included in the recommended computational formulae. The proper general physical analysis refers to rather complicated problems from classical thermodynamics, whose both existence theory and numerical analysis contain open questions and cannot be done in practice when the optimization of composition of insulation layers is required. This paper, coming from original experimental results, demonstrates an alternative simplified computational approach, taking into account the most important physical processes, useful in the design of modern insulation systems.

  9. Vacuum Ultraviolet Radiation and Atomic Oxygen Durability Evaluation of HST Bi-Stem Thermal Shield Materials

    Science.gov (United States)

    Dever, Joyce; deGroh, Kim K.

    2002-01-01

    Bellows-type thermal shields were used on the bi-stems of replacement solar arrays installed on the Hubble Space Telescope (HST) during the first HST servicing mission (SMI) in December 1993. These thermal shields helped reduce the problem of thermal gradient- induced jitter observed with the original HST solar arrays during orbital thermal cycling and have been in use on HST for eight years. This paper describes ground testing of the candidate solar array bi-stem thermal shield materials including backside aluminized Teflon(R)FEP (fluorinated ethylene propylene) with and without atomic oxygen (AO) and ultraviolet radiation protective surface coatings for durability to AO and combined AO and vacuum ultraviolet (VOV) radiation. NASA Glenn Research Center (GRC) conducted VUV and AO exposures of samples of candidate thermal shield materials at HST operational temperatures and pre- and post-exposure analyses as part of an overall program coordinated by NASA Goddard Space Flight Center (GSFC) to determine the on-orbit durability of these materials. Coating adhesion problems were observed for samples having the AO- and combined AO/UV-protective coatings. Coating lamination occurred with rapid thermal cycling testing which simulated orbital thermal cycling. This lack of adhesion caused production of coating flakes from the material that would have posed a serious risk to HST optics if the coated materials were used for the bi-stem thermal shields. No serious degradation was observed for the uncoated aluminized Teflon(R) as evaluated by optical microscopy, although atomic force microscopy (AFM) microhardness testing revealed that an embrittled surface layer formed on the uncoated Teflon(R) surface due to vacuum ultraviolet radiation exposure. This embrittled layer was not completely removed by AO erosion, No cracks or particle flakes were produced for the embrittled uncoated material upon exposure to VUV and AO at operational temperatures to an equivalent exposure of

  10. Thermal melting and ablation of silicon by femtosecond laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ionin, A. A.; Kudryashov, S. I., E-mail: sikudr@lebedev.ru; Seleznev, L. V.; Sinitsyn, D. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Bunkin, A. F.; Lednev, V. N.; Pershin, S. M. [Russian Academy of Sciences, General Physics Institute (Russian Federation)

    2013-03-15

    The space-time dynamics of thermal melting, subsurface cavitation, spallative ablation, and fragmentation ablation of the silicon surface excited by single IR femtosecond laser pulses is studied by timeresolved optical reflection microscopy. This dynamics is revealed by monitoring picosecond and (sub)nanosecond oscillations of probe pulse reflection, which is modulated by picosecond acoustic reverberations in the dynamically growing surface melt subjected to ablation and having another acoustic impedance, and by optical interference between the probe pulse replicas reflected by the spalled layer surface and the layer retained on the target surface. The acoustic reverberation periods change during the growth and ablation of the surface melt film, which makes it possible to quantitatively estimate the contributions of these processes to the thermal dynamics of the material surface. The results on the thermal dynamics of laser excitation are supported by dynamic measurements of the ablation parameters using noncontact ultrasonic diagnostics, scanning electron microscopy, atomic force microscopy, and optical interference microscopy of the modified regions appearing on the silicon surface after ablation.

  11. Thermal slip for liquids at rough solid surfaces

    Science.gov (United States)

    Zhang, Chengbin; Chen, Yongping; Peterson, G. P.

    2014-06-01

    Molecular dynamics simulation is used to examine the thermal slip of liquids at rough solid surfaces as characterized by fractal Cantor structures. The temperature profiles, potential energy distributions, thermal slip, and interfacial thermal resistance are investigated and evaluated for a variety of surface topographies. In addition, the effects of liquid-solid interaction, surface stiffness, and boundary condition on thermal slip length are presented. Our results indicate that the presence of roughness expands the low potential energy regions in adjacent liquids, enhances the energy transfer at liquid-solid interface, and decreases the thermal slip. Interestingly, the thermal slip length and thermal resistance for liquids in contact with solid surfaces depends not only on the statistical roughness height, but also on the fractal dimension (i.e., topographical spectrum).

  12. Finite dipole model for extreme near-field thermal radiation between a tip and planar SiC substrate

    Science.gov (United States)

    Jarzembski, Amun; Park, Keunhan

    2017-04-01

    Recent experimental studies have measured the infrared (IR) spectrum of tip-scattered near-field thermal radiation for a SiC substrate and observed up to a 50cm-1 redshift of the surface phonon polariton (SPhP) resonance peak [1,2]. However, the observed spectral redshift cannot be explained by the conventional near-field thermal radiation model based on the point dipole approximation. In the present work, a heated tip is modeled as randomly fluctuating point charges (or fluctuating finite dipoles) aligned along the primary axis of a prolate spheroid, and quasistatic tip-substrate charge interactions are considered to formulate the effective polarizability and self-interaction Green's function. The finite dipole model (FDM), combined with fluctuational electrodynamics, allows the computation of tip-plane thermal radiation in the extreme near-field (i.e., H / R ≲ 1 , where H is the tip-substrate gap distance and R is the tip radius), which cannot be calculated with the point dipole approximation. The FDM provides the underlying physics on the spectral redshift of tip-scattered near-field thermal radiation as observed in experiments. In addition, the SPhP peak in the near-field thermal radiation spectrum may split into two peaks as the gap distance decreases into the extreme near-field regime. This observation suggests that scattering-type spectroscopic measurements may not convey the full spectral features of tip-plane extreme near-field thermal radiation.

  13. Response of nickel surface to pulsed fusion plasma radiations

    Energy Technology Data Exchange (ETDEWEB)

    Niranjan, Ram, E-mail: niranjan@barc.gov.in; Rout, R. K., E-mail: niranjan@barc.gov.in; Srivastava, R., E-mail: niranjan@barc.gov.in; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Chakravarthy, Y. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Patel, N. N. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Alex, P. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2014-04-24

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  14. Spectral emissivity measurements of land-surface materials and related radiative transfer simulations

    Science.gov (United States)

    Wan, Z.; Ng, D.; Dozier, J.

    1994-01-01

    Spectral radiance measurements have been made in the laboratory and in the field for deriving spectral emissivities of some land cover samples with a spectroradiometer and an auxiliary radiation source in the wavelength range 2.5-14.5 micrometers. A easy and quick four-step method (four steps to measure the sample and a diffuse reflecting plate surface under sunshine and shadowing conditions, respectively) has been used for simultaneous determination of surface temperature and emissivity. We emphasized in-situ measurements in combination with radiative transfer simulations, and an error analysis for basic assumptions in deriving spectral emissivity of land-surface samples from thermal infrared measurements.

  15. Impact of thermal radiation on MHD slip flow of a ferrofluid over a non-isothermal wedge

    Science.gov (United States)

    Rashad, A. M.

    2017-01-01

    This article is concerned with the problem of magnetohydrodynamic (MHD) mixed convection flow of Cobalt-kerosene ferrofluid adjacent a non-isothermal wedge under the influence of thermal radiation and partial slip. Such type of problems are posed by electric generators and biomedical enforcement. The governing equations are solved using the Thomas algorithm with finite-difference type and solutions for a wide range of magnet parameter are presented. It is found that local Nusselt number manifests a considerable diminishing for magnetic parameter and magnifies intensively in case of slip factor, thermal radiation and surface temperature parameters. Further, the skin friction coefficient visualizes a sufficient enhancement for the parameters thermal radiation, surface temperature and magnetic field, but a huge reduction is recorded by promoting the slip factor.

  16. The use of the diffusion approximation for simulating radiation and thermal processes in the skin

    Science.gov (United States)

    Kovtanyuk, A. E.; Grenkin, G. V.; Chebotarev, A. Yu.

    2017-08-01

    Radiation and thermal processes in skin exposed to solar radiation are simulated based on the diffusion model of radiative-conductive heat exchange. Using the model proposed for the parameters corresponding to radiation with a wavelength of 800 nm, the contributions of thermal radiation induced by the skin and the reflection and refraction effects are estimated, and the photoprotective properties of titanium dioxide nanoparticles (TiO2) when introduced into the stratum corneum are studied.

  17. NASA/GEWEX Surface Radiation Budget (SRB) Data and Info

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA/GEWEX Surface Radiation Budget (SRB) Release-3.0 data sets contains global 3-hourly, daily, monthly/3-hourly, and monthly averages of surface and top-of...

  18. Non-thermal Axion Dark Radiation and Constraints

    CERN Document Server

    Mazumdar, Anupam; Saikawa, Ken'ichi

    2016-01-01

    The Peccei-Quinn mechanism presents a neat solution to the strong CP problem. As a by-product, it provides an ideal dark matter candidate, "the axion", albeit with a tiny mass. Axions therefore can act as dark radiation if excited with large momenta after the end of inflation. Nevertheless, the recent measurement of relativistic degrees of freedom from cosmic microwave background radiation strictly constrains the abundance of such extra relativistic species. We show that ultra-relativistic axions can be abundantly produced if the Peccei-Quinn field was initially displaced from the minimum of the potential. This in lieu places an interesting constraint on the axion dark matter window with large decay constant which is expected to be probed by future experiments. Moreover, an upper bound on the reheating temperature can be placed, which further constrains the thermal history of our Universe.

  19. Non-thermal electromagnetic radiation damage to lens epithelium.

    Science.gov (United States)

    Bormusov, Elvira; P Andley, Usha; Sharon, Naomi; Schächter, Levi; Lahav, Assaf; Dovrat, Ahuva

    2008-05-21

    High frequency microwave electromagnetic radiation from mobile phones and other modern devices has the potential to damage eye tissues, but its effect on the lens epithelium is unknown at present. The objective of this study was to investigate the non-thermal effects of high frequency microwave electromagnetic radiation (1.1GHz, 2.22 mW) on the eye lens epithelium in situ. Bovine lenses were incubated in organ culture at 35°C for 10-15 days. A novel computer-controlled microwave source was used to investigate the effects of microwave radiation on the lenses. 58 lenses were used in this study. The lenses were divided into four groups: (1) Control lenses incubated in organ culture for 10 to15 days. (2) Electromagnetic radiation exposure group treated with 1.1 GHz, 2.22 mW microwave radiation for 90 cycles of 50 minutes irradiation followed by 10 minutes pause and cultured up to 10 days. (3) Electromagnetic radiation exposure group treated as group 2 with 192 cycles of radiation and cultured for 15 days. (4) Lenses exposed to 39.5°C for 2 hours 3 times with 24 hours interval after each treatment beginning on the second day of the culture and cultured for 11 days. During the culture period, lens optical quality was followed daily by a computer-operated scanning laser beam. At the end of the culture period, control and treated lenses were analyzed morphologically and by assessment of the lens epithelial ATPase activity. Exposure to 1.1 GHz, 2.22 mW microwaves caused a reversible decrease in lens optical quality accompanied by irreversible morphological and biochemical damage to the lens epithelial cell layer. The effect of the electromagnetic radiation on the lens epithelium was remarkably different from those of conductive heat. The results of this investigation showed that electromagnetic fields from microwave radiation have a negative impact on the eye lens. The lens damage by electromagnetic fields was distinctly different from that caused by conductive heat.

  20. Thermal self-oscillations in radiative heat exchange

    CERN Document Server

    Dyakov, Sergey; Yan, Min; Qiu, Min

    2014-01-01

    We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO$_2$ and VO$_2$ which exchange heat by thermal radiation in vacuum. The nonlinear feedback in the self-oscillating system is provided by metal-insulator transition in VO$_2$. Using the method of fluctuational electrodynamics we show that under the action of external laser of a constant power, the temperature of VO$_2$ plate oscillates around its phase transition value.

  1. Radiated Susceptibility Tests in Thermal Vacuum Chambers for Space Systems

    Science.gov (United States)

    Anon Cancela, Manuel; Hernandez-Gomez, Daniel; Vazquez-Pascual, Mercedes; Lopez-Sanz, Daniel

    2016-05-01

    INTA EMC Area has a wide experience in performing Radiated Susceptibility (RS) tests according to civilian, military and aeronautical standards in Mode Tuned Chambers (MTC) for national and international projects; besides, INTA has two Thermal Vacuum Chamber (TVC) facilities in service for Space Systems tests. In order to perform RS tests to Space Systems in a more realistic environment, INTA EMC Area has stablished an internal research program to develop a procedure to perform this kind of tests inside a TVC as a Mode Tuned Chamber (MTC). In this paper the results of the TVC-04 validation measurements as a MTC are presented.

  2. Advanced Computational Methods for Thermal Radiative Heat Transfer.

    Energy Technology Data Exchange (ETDEWEB)

    Tencer, John; Carlberg, Kevin Thomas; Larsen, Marvin E.; Hogan, Roy E.,

    2016-10-01

    Participating media radiation (PMR) in weapon safety calculations for abnormal thermal environments are too costly to do routinely. This cost may be s ubstantially reduced by applying reduced order modeling (ROM) techniques. The application of ROM to PMR is a new and unique approach for this class of problems. This approach was investigated by the authors and shown to provide significant reductions in the computational expense associated with typical PMR simulations. Once this technology is migrated into production heat transfer analysis codes this capability will enable the routine use of PMR heat transfer in higher - fidelity simulations of weapon resp onse in fire environments.

  3. Dilution of axion dark radiation by thermal inflation

    CERN Document Server

    Hattori, Hironori; Omoto, Naoya; Seto, Osamu

    2015-01-01

    Axion in the Peccei-Quinn (PQ) mechanism provides a promising solution to the strong CP problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would confront with the current dark radiation constraints. We study the possibility that a thermal inflation driven by a $U(1)$ gauged Higgs field dilutes such axions. A well motivated extra gauged $U(1)$ would be the local $B-L$ symmetry. We also discuss the implication for the case of $U(1)_{B-L}$ and available baryogenesis mechanism in such cosmology.

  4. Dilution of axion dark radiation by thermal inflation

    Science.gov (United States)

    Hattori, Hironori; Kobayashi, Tatsuo; Omoto, Naoya; Seto, Osamu

    2015-07-01

    Axions in the Peccei-Quinn (PQ) mechanism provide a promising solution to the strong C P problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would conflict with the current dark radiation constraints. We study the possibility that a thermal inflation driven by a U (1 ) gauged Higgs field dilutes such axions. A well-motivated extra gauged U (1 ) would be the local B -L symmetry. We also discuss the implication for the case of U (1 )B-L and an available baryogenesis mechanism in such cosmology.

  5. Advanced Computational Methods for Thermal Radiative Heat Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Tencer, John; Carlberg, Kevin Thomas; Larsen, Marvin E.; Hogan, Roy E.,

    2016-10-01

    Participating media radiation (PMR) in weapon safety calculations for abnormal thermal environments are too costly to do routinely. This cost may be s ubstantially reduced by applying reduced order modeling (ROM) techniques. The application of ROM to PMR is a new and unique approach for this class of problems. This approach was investigated by the authors and shown to provide significant reductions in the computational expense associated with typical PMR simulations. Once this technology is migrated into production heat transfer analysis codes this capability will enable the routine use of PMR heat transfer in higher - fidelity simulations of weapon resp onse in fire environments.

  6. Near-field thermal imaging of nanostructured surfaces

    Science.gov (United States)

    Kittel, A.; Wischnath, U. F.; Welker, J.; Huth, O.; Rüting, F.; Biehs, S.-A.

    2008-11-01

    We show that a near-field scanning thermal microscope, which essentially detects the local density of states of the thermally excited electromagnetic modes at nanometer distances from some material, can be employed for nanoscale imaging of structures on that material's surface. This finding is explained theoretically by an approach which treats the surface structure perturbatively.

  7. Thermal Performance of Hollow Clay Brick with Low Emissivity Treatment in Surface Enclosures

    Directory of Open Access Journals (Sweden)

    Roberto Fioretti

    2014-10-01

    Full Text Available External walls made with hollow clay brick or block are widely used for their thermal, acoustic and structural properties. However, the performance of the bricks frequently does not conform with the minimum legal requirements or the values required for high efficiency buildings, and for this reason, they need to be integrated with layers of thermal insulation. In this paper, the thermal behavior of hollow clay block with low emissivity treatment on the internal cavity surfaces has been investigated. The purpose of this application is to obtain a reduction in the thermal conductivity of the block by lowering the radiative heat exchange in the enclosures. The aims of this paper are to indicate a methodology for evaluating the thermal performance of the brick and to provide information about the benefits that should be obtained. Theoretical evaluations are carried out on several bricks (12 geometries simulated with two different thermal conductivities of the clay, using a finite elements model. The heat exchange procedure is implemented in accordance with the standard, so as to obtain standardized values of the thermal characteristics of the block. Several values of emissivity are hypothesized, related to different kinds of coating. Finally, the values of the thermal transmittance of walls built with the evaluated blocks have been calculated and compared. The results show how coating the internal surface of the cavity provides a reduction in the thermal conductivity of the block, of between 26% and 45%, for a surface emissivity of 0.1.

  8. Radiation-induced polymerization and grafting of {beta}(-)pinene on silica surface

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco [Lupi Chemical Research Institute, Via Casilina 1626/A, 00133 Rome (Italy)], E-mail: cdcata@flashnet.it; Ursini, Ornella; Lilla, Edo; Angelini, Giancarlo [CNR, Institute of Chemical Metodologies, Area della Ricerca di Roma 1, Monterotondo Scalo, Rome (Italy)

    2008-05-15

    Poly-{beta}-pinene (pBp) was obtained on silica surface by {gamma} radiation-induced polymerization of {beta}(-)pinene in presence of silica gel with a specific surface area of 300 m{sup 2}/g. Different radiation doses were employed in the range 50-332 kGy. The pBp-silica hybrid samples obtained have been characterized by FT-IR spectroscopy and the amount of pBp on silica surface has been determined both by gravimetric and TGA measurements. The fraction of pBp chemically grafted on silica surface has been determined by the extraction of the pBp-silica hybrid with boiling toluene and was found to be 10-20% of the total pBp formed on silica surface. The optical activity of pBp extracted from the hybrid was studied by polarimetric measurements and found slightly lower than the typical specific optical rotation of pBp polymerized in bulk with radiation. The thermal stability of the pBp-silica hybrid materials was studied by thermogravimetric and differential thermal analysis. The results show lower thermal stability for the pBp-silica hybrid in comparison to pure pBp. Evidently, silica catalyzes the thermal decomposition of pBp at lower temperatures. Use of the pBp-silica hybrid as stationary phase for liquid chromatography for chiral separations has been proposed.

  9. Effect of powder compaction on radiation-thermal synthesis of lithium-titanium 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

    Effect of powder compaction on the efficiency of thermal and radiation-thermal synthesis of lithium-substituted ferrites was investigated by X-Ray diffraction and specific magnetization analysis. It was shown that the radiation-thermal heating of compacted powder reagents mixture leads to an increase in efficiency of lithium-titanium ferrites synthesis.

  10. Surface energy budget responses to radiative forcing at Summit, Greenland

    Science.gov (United States)

    Miller, Nathaniel B.; Shupe, Matthew D.; Cox, Christopher J.; Noone, David; Persson, P. Ola G.; Steffen, Konrad

    2017-02-01

    Greenland Ice Sheet surface temperatures are controlled by an exchange of energy at the surface, which includes radiative, turbulent, and ground heat fluxes. Data collected by multiple projects are leveraged to calculate all surface energy budget (SEB) terms at Summit, Greenland, for the full annual cycle from July 2013 to June 2014 and extend to longer periods for the radiative and turbulent SEB terms. Radiative fluxes are measured directly by a suite of broadband radiometers. Turbulent sensible heat flux is estimated via the bulk aerodynamic and eddy correlation methods, and the turbulent latent heat flux is calculated via a two-level approach using measurements at 10 and 2 m. The subsurface heat flux is calculated using a string of thermistors buried in the snow pack. Extensive quality-control data processing produced a data set in which all terms of the SEB are present 75 % of the full annual cycle, despite the harsh conditions. By including a storage term for a near-surface layer, the SEB is balanced in this data set to within the aggregated uncertainties for the individual terms. November and August case studies illustrate that surface radiative forcing is driven by synoptically forced cloud characteristics, especially by low-level, liquid-bearing clouds. The annual cycle and seasonal diurnal cycles of all SEB components indicate that the non-radiative terms are anticorrelated to changes in the total radiative flux and are hence responding to cloud radiative forcing. Generally, the non-radiative SEB terms and the upwelling longwave radiation component compensate for changes in downwelling radiation, although exact partitioning of energy in the response terms varies with season and near-surface characteristics such as stability and moisture availability. Substantial surface warming from low-level clouds typically leads to a change from a very stable to a weakly stable near-surface regime with no solar radiation or from a weakly stable to neutral

  11. Radiation, Thermal Gradient and Weight: a threefold dilemma for PLATO

    Science.gov (United States)

    Magrin, Demetrio; Ragazzoni, Roberto; Bruno, Giordano; Piazza, Daniele; Borsa, Francesco; Ghigo, Mauro; Mogulsky, Valery; Bergomi, Maria; Biondi, Federico; Chinellato, Simonetta; Dima, Marco; Farinato, Jacopo; Greggio, Davide; Gullieuszik, Marco; Marafatto, Luca; Viotto, Valentina; Munari, Matteo; Pagano, Isabella; Sicilia, Daniela; Basso, Stefano; Spiga, Daniele; Bandy, Timothy; Brändli, Mathias; Benz, Willy; De Roche, Thierry; Rieder, Martin; Brandeker, Alexis; Klebor, Maximilian; Schweitzer, Mario; Wieser, Matthias; Erikson, Anders; Rauer, Heike

    2016-07-01

    The project PLAnetary Transits and Oscillations of stars (PLATO) is one of the selected medium class (M class) missions in the framework of the ESA Cosmic Vision 2015-2025 program. The mean scientific goal of PLATO is the discovery and study of extrasolar planetary systems by means of planetary transits detection. The opto mechanical subsystem of the payload is made of 32 normal telescope optical units (N-TOUs) and 2 fast telescope optical units (FTOUs). The optical configuration of each TOU is an all refractive design based on six properly optimized lenses. In the current baseline, in front of each TOU a Suprasil window is foreseen. The main purposes of the entrance window are to shield the following lenses from possible damaging high energy radiation and to mitigate the thermal gradient that the first optical element will experience during the launch from ground to space environment. In contrast, the presence of the window increases the overall mass by a non-negligible quantity. We describe here the radiation and thermal analysis and their impact on the quality and risks assessment, summarizing the trade-off process with pro and cons on having or dropping the entrance window in the optical train.

  12. Study of mass loss of spacecraft polymeric thermal control coatings under electron and proton radiations

    Science.gov (United States)

    Khasanshin, Rashid; Novikov, Lev; Galygin, Alexander

    Polymeric composites have a number of properties that give a possibility to apply them as spacecraft external coatings. In space environment, however, such materials become one of the main sources of volatile products that form the outer spacecraft atmosphere and are able to con-dense on contamination-sensitive surfaces of onboard equipment. Thermal control coatings oc-cupy a considerable part of a satellite surface and are mostly subjected to ionizing radiations ac-companying by outgassing. The main stages of the process are the following: formation of vola-tile radiolysis products, diffusion of the products to free material surface, and desorption. Radia-tion-induced destruction and outgassing of material increase its permeability and accelerate mi-gration processes in it. Experimental data of effect of radiation on mass loss of polymeric composites used as thermal control coatings was analyzed and interpreted in the work. As a particular case, it was shown that mass loss of a polymeric composite irradiated by protons is greater than by electrons if energies and flux densities of the particles are the same. It can be explained that volatile products, in the first case, generate within a thin near-surface layer of material which permeability increases together with the absorbed dose, and quickly escape in vacuum. In the second case, a bulk of volatile products emerges far enough from the free surface of material which permeability increases slower as compared with proton radiation. Therefore, migration time of volatile products to the free surface grows and quantity of chemical reactions which they are involved in increases. To analyze and interpret experimental data, a mathematical model describing mass loss of polymeric composites subject to its growth of permeability under radiation is proposed. Based upon analysis of experiments and numerical simulation results, thresholds of fluen-cies and flux densities of electron and proton were determined. Exceeding these

  13. Observed Asteroid Surface Area in the Thermal Infrared

    Science.gov (United States)

    Nugent, C. R.; Mainzer, A.; Masiero, J.; Wright, E. L.; Bauer, J.; Grav, T.; Kramer, E.; Sonnett, S.

    2017-02-01

    The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emitted flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.

  14. Small business innovation program. Phase 1: Selective thermal radiators

    Science.gov (United States)

    Hauer, C. R.

    1980-05-01

    Experiments used ion implantation to modify the radiation and evaporation surface properties of tungsten filaments operating at about 2800 K. Tungsten filaments ion implanted with carbon at low energy showed an ability to dissipate more energy than unimplanted tungsten filaments when operated in parallel prior to filament failure. Infrared reflectance measurements of a blackbody source indicated anomolous behavior, in that the reflectance and emittance of the surface appeared to be a strong function of the wavelength in the vicinity of the period. There appeared to be a concomitant shift toward longer wavelengths in the peak of the reflected blackbody radiance spectrum when a periodically structured reflector was used.

  15. Modeling simulation of the thermal radiation for high-speed flight vehicles' aero-optical windows

    Science.gov (United States)

    Chen, Lei; Zhang, Liqin; Guo, Mingjiang

    2015-10-01

    When high-speed flight vehicles fly in the atmosphere, they can generate serious aero-optical effect. The optical window temperature rises sharply because of aerodynamic heating. It will form radiation interference that can lead infrared detectors to producing non-uniform radiation backgrounds, decreasing system SNR and detection range. Besides, there exits temperature difference due to uneven heating. Under the thermo-optical and elastic-optical effects, optical windows change into inhomogeneous mediums which influence the ray propagation. In this paper, a model of thermal radiation effect was built by a finite element analysis method. Firstly, the optical window was divided into uniform grids. Then, radiation distribution on the focal planes at different angles of the window's normal line and optical axis was obtained by tracing light rays of each grid. Finally, simulation results indicate that radiation distribution reflects the two directions-the length and width-of temperature distribution, and the change of angle causes the center of radiation distribution to shift to one direction of the image surface under the same window temperature.

  16. Magnetohydrodynamic three-dimensional flow of viscoelastic nanofluid in the presence of nonlinear thermal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589 (Saudi Arabia); Muhammad, Taseer, E-mail: taseer_qau@yahoo.com [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Alsaedi, A.; Alhuthali, M.S. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2015-07-01

    Magnetohydrodynamic (MHD) three-dimensional flow of couple stress nanofluid in the presence of thermophoresis and Brownian motion effects is analyzed. Energy equation subject to nonlinear thermal radiation is taken into account. The flow is generated by a bidirectional stretching surface. Fluid is electrically conducting in the presence of a constant applied magnetic field. The induced magnetic field is neglected for a small magnetic Reynolds number. Mathematical formulation is performed using boundary layer analysis. Newly proposed boundary condition requiring zero nanoparticle mass flux is employed. The governing nonlinear mathematical problems are first converted into dimensionless expressions and then solved for the series solutions of velocities, temperature and nanoparticles concentration. Convergence of the constructed solutions is verified. Effects of emerging parameters on the temperature and nanoparticles concentration are plotted and discussed. Skin friction coefficients and Nusselt number are also computed and analyzed. It is found that the thermal boundary layer thickness is an increasing function of radiative effect. - Highlights: • Three-dimensional boundary layer flow of viscoelastic nanofluid is examined. • Nonlinear thermal radiation is analyzed. • Brownian motion and thermophoresis effects are present. • Recently developed condition requiring zero nanoparticle mass flux is implemented. • Construction of convergent solutions of nonlinear flow is possible.

  17. Laser pulse heating of surfaces and thermal stress analysis

    CERN Document Server

    Yilbas, Bekir S; Al-Aqeeli, Nasser; Al-Qahtani, Hussain M

    2013-01-01

    This book introduces laser pulse heating and thermal stress analysis in materials surface. Analytical temperature treatments and stress developed in the surface region are also explored. The book will help the reader analyze the laser induced stress in the irradiated region and presents solutions for the stress field. Detailed thermal stress analysis in different laser pulse heating situations and different boundary conditions are also presented. Written for surface engineers.

  18. Improvements to a Response Surface Thermal Model for Orion

    Science.gov (United States)

    Miller, Stephen W.; Walker, William Q.

    2011-01-01

    A study was performed to determine if a Design of Experiments (DOE)/Response Surface Methodology could be applied to on-orbit thermal analysis and produce a set of Response Surface Equations (RSE) that predict Orion vehicle temperatures within 10 F. The study used the Orion Outer Mold Line model. Five separate factors were identified for study: yaw, pitch, roll, beta angle, and the environmental parameters. Twenty-three external Orion components were selected and their minimum and maximum temperatures captured over a period of two orbits. Thus, there are 46 responses. A DOE case matrix of 145 runs was developed. The data from these cases were analyzed to produce a fifth order RSE for each of the temperature responses. For the 145 cases in the DOE matrix, the agreement between the engineering data and the RSE predictions was encouraging with 40 of the 46 RSEs predicting temperatures within the goal band. However, the verification cases showed most responses did not meet the 10 F goal. After reframing the focus of the study to better align the RSE development with the purposes of the model, a set of RSEs for both the minimum and maximum radiator temperatures was produced which predicted the engineering model output within +/-4 F. Therefore, with the correct application of the DOE/RSE methodology, RSEs can be developed that provide analysts a fast and easy way to screen large numbers of environments and assess proposed changes to the RSE factors.

  19. Surface Radiation from GOES: A Physical Approach; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Habte, A.; Sengupta, M.; Wilcox, S.

    2012-09-01

    Models to compute Global Horizontal Irradiance (GHI) and Direct Normal Irradiance (DNI) have been in development over the last 3 decades. These models can be classified as empirical or physical, based on the approach. Empirical models relate ground based observations with satellite measurements and use these relations to compute surface radiation. Physical models consider the radiation received from the earth at the satellite and create retrievals to estimate surface radiation. While empirical methods have been traditionally used for computing surface radiation for the solar energy industry the advent of faster computing has made operational physical models viable. The Global Solar Insolation Project (GSIP) is an operational physical model from NOAA that computes GHI using the visible and infrared channel measurements from the GOES satellites. GSIP uses a two-stage scheme that first retrieves cloud properties and uses those properties in a radiative transfer model to calculate surface radiation. NREL, University of Wisconsin and NOAA have recently collaborated to adapt GSIP to create a 4 km GHI and DNI product every 30 minutes. This paper presents an outline of the methodology and a comprehensive validation using high quality ground based solar data from the National Oceanic and Atmospheric Administration (NOAA) Surface Radiation (SURFRAD) (http://www.srrb.noaa.gov/surfrad/sitepage.html) and Integrated Surface Insolation Study (ISIS) http://www.srrb.noaa.gov/isis/isissites.html), the Solar Radiation Research Laboratory (SRRL) at National Renewable Energy Laboratory (NREL), and Sun Spot One (SS1) stations.

  20. Spectral Radiative Properties of Two-Dimensional Rough Surfaces

    Science.gov (United States)

    Xuan, Yimin; Han, Yuge; Zhou, Yue

    2012-12-01

    Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.

  1. Thermal radiation antennas made of multilayer structures containing negative index metamaterials

    NARCIS (Netherlands)

    Maksimovic, M.; Hammer, M.; Jaksic, Z.; Greiner, C.M.; Waechter, C.A.

    2008-01-01

    We investigate the thermal antenna behavior of emissive/absorptive substrates coated by passive optical multilayer systems that contain negative refractive index metamaterials (NIM). Spectral and angular distributions of the thermal radiation emittance for periodic defect-containing multilayer with

  2. Thermal radiation antennas made of multilayer structures containing negative index metamaterials

    NARCIS (Netherlands)

    Maksimovic, Milan; Lohmeyer, Manfred; Jaksic, Z.; Greiner, C.M.; Waechter, C.A.

    2008-01-01

    We investigate the thermal antenna behavior of emissive/absorptive substrates coated by passive optical multilayer systems that contain negative refractive index metamaterials (NIM). Spectral and angular distributions of the thermal radiation emittance for periodic defect-containing multilayer with

  3. Parylene-based active micro space radiator with thermal contact switch

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Ai; Suzuki, Yuji [Department of Mechanical Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-03-03

    Thermal management is crucial for highly functional spacecrafts exposed to large fluctuations of internal heat dissipation and/or thermal boundary conditions. Since thermal radiation is the only means for heat removal, effective control of radiation is required for advanced space missions. In the present study, a MEMS (Micro Electro Mechanical Systems) active radiator using the contact resistance change has been proposed. Unlike previous bulky thermal louvers/shutters, higher fill factor can be accomplished with an array of electrostatically driven micro diaphragms suspended with polymer tethers. With an early prototype developed with parylene MEMS technologies, radiation heat flux enhancement up to 42% has been achieved.

  4. COHERENT INFORMATION ON THERMAL RADIATION NOISE CHANNEL: AN APPROACH OF INTEGRAL WITHIN ORDERED PRODUCT OF OPERATORS

    Institute of Scientific and Technical Information of China (English)

    陈小余; 仇佩亮

    2001-01-01

    An analytical expression is given to the coherent information of the thermal radiation signal transmitted over the thermal radiation noise channel, one of the most essential quantum Gaussian channels. Focusing on the single normal mode of the thermal radiation signal and noise, we resolve the entangled state density operator, which characterizes quantum information transmission, into a direct product of two parts, with each part being a thermal radiation density operator. The calculation is aided by the technique known as "integral within ordered product of operators".

  5. Non-thermal Radiation Processes in Relativistic Outflows from AGN

    Science.gov (United States)

    Lefa, Eva

    2012-11-01

    Non-thermal, leptonic radiation processes have been extensively studied for the interpretation of the observed radiation from jets of Active Galactic Nuclei (AGN). This work addresses the synchrotron and Inverse Compton scattering (ICS) mechanisms, and investigates the potential of a self-consistent, time-dependent approach to currently unsolved problems. Furthermore, it examines how deviations from standard, one-zone models can modify the radiated spectrum. A detailed analysis of the shape of the ICS spectrum is also performed. In the first part a possible interpretation of the hard γ-ray blazar spectra in the framework of leptonic models is investigated. It is demonstrated that hard γ-ray spectra can be generated and maintained in the presence of energy losses, under the basic assumption of a narrow electron energy distribution (EED). Broader spectra can also be modeled if multiple zones contribute to the emission. In such a scheme, hard flaring events, like the one in Mkn 501 in 2009, can be successfully interpreted within a "leading blob" scenario, when one or few zones of emission become dominant. In the second part the shape of the Compton spectrum close to the maximum cutoff is investigated. Analytical approximations for the spectral shape in the cutoff region are derived for various soft photon fields, providing a direct link between the parent EED and the upscattered spectrum. Additionally, a generalization of the beaming pattern for various processes is derived, which accounts for non-stationary, anisotropic and non-homogeneous EEDs. It is shown that anisotropic EEDs may lead to radiated spectra substantially different from the isotropic case. Finally, a self-consistent, non-homogeneous model describing the synchrotron emission from stratified jets is developed. It is found that transverse jet stratification leads to characteristic features in the emitted spectrum different to expectations in homogeneous models.

  6. An overview of micro/nanoscaled thermal radiation and its applications

    Science.gov (United States)

    Xuan, Yimin

    2014-04-01

    With the rapid development of micro/nanoscaled technologies, we are confronted with more and more challenges related to small-scale thermal radiation. Thorough understanding and handling of micro/nanoscaled radiative heat transfer is vital for many fields of modern science and technology. For example, proper utilization of near-field thermal radiation phenomenon greatly improves light-electric conversion efficiency. This review introduces theoretical and experimental investigation on near-field thermal radiation, especially progress in application and control of micro/nanoscaled radiative heat transfer, which addresses problems in developing renewable and sustainable energy techniques.

  7. Surface Coatings for Low Emittance in the Thermal Surveillance Band

    Science.gov (United States)

    1984-08-01

    radiation emanating from the sky during the day and at night [13]; 2 - (2) -the geometry, surface topography, and surface cleanliness of the target and the... surface cleanliness . A description of terms and definitions used in reflectometry is provided by Judd [19] and Overington (20]. Measurement standards

  8. An Analysis of Thermally-Related Surface Rainfall Budgets Associated with Convective and Stratiform Rainfall

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yushu; Xiaofan LI

    2011-01-01

    Both water vapor and heat processes play key roles in producing surface rainfall.While the water vapor effects of sea surface temperature and cloud radiative and microphysical processes on surface rainfall have been investigated in previous studies,the thermal effects on rainfall are analyzed in this study using a series of two-dimensional equilibrium cloud-resolving model experiments forced by zonally-uniform,constant,large-scale zonal wind and zero large-scale vertical velocity.The analysis of thermally-related surface rainfall budget reveals that the model domain mean surface rain rate is primarily associated with the mean infrared cooling rate.Convective rainfall and transport of hydrometeor concentration from convective regions to raining stratiform regions corresponds to the heat divergence over convective regions,whereas stratiform rainfall corresponds to the transport of hydrometeor concentration from convective regions and heat divergence over raining stratiform regions.The heat divergence over convective regions is mainly balanced by the heat convergence over rainfall-free regions,which is,in turn,offset by the radiative cooling over rainfall-free regions.The sensitivity experiments of rainfall to the effects of sea surface temperature and cloud radiative and microphysical processes show that the sea surface temperature and cloud processes affect convective rainfall through the changes in infrared cooling rate over rainfall-free regions and transport rate of heat from convective regions to rainfall-free regions.

  9. Free Convective Nonaligned Non-Newtonian Flow with Non-linear Thermal Radiation

    Science.gov (United States)

    Rana, S.; Mehmood, R.; Narayana, PV S.; Akbar, N. S.

    2016-12-01

    The present study explores the free convective oblique Casson fluid over a stretching surface with non-linear thermal radiation effects. The governing physical problem is modelled and transformed into a set of coupled non-linear ordinary differential equations by suitable similarity transformation, which are solved numerically with the help of shooting method keeping the convergence control of 10-5 in computations. Influence of pertinent physical parameters on normal, tangential velocity profiles and temperature are expressed through graphs. Physical quantities of interest such as skin friction coefficients and local heat flux are investigated numerically.

  10. Thermally Driven Winds from Radiatively Inefficient Accretion Flows

    CERN Document Server

    Kawabata, Ryoji

    2009-01-01

    Radiatively inefficient accretion flows (RIAFs) are common feature of low-luminosity accretion flows, including quiescent states of X-ray binaries and low-lunimosity active galactic nuclei. Thermally driven winds are expected from such hot accretion flows. By assuming that the flow has self-similarity structure in the radial direction, we solve the vertical structure of the wind and accretion flows simultaneously and evaluate the mass loss rates by wind. We find that the ratio of the outflow rate to the accretion rate is approximately unity for a viscosity parameter, alpha lesssim 0.1, despite some uncertainties in the angular momentum and temperature distributions. That is, the accretion rate in the RIAFs is roughly proportional to the radius. Moreover, we elucidate the effect of cooling by wind on the underneath accretion flow, finding that this effect could be important for calculating energy spectrum of the RIAF. Observational implications are briefly discussed in the context of Sgr A*.

  11. Two-temperature radiative shocks with electron thermal conduction

    Science.gov (United States)

    Borkowski, Kazimierz J.; Shull, J. Michael; Mckee, Christopher F.

    1989-01-01

    The influence of electron thermal conduction on radiative shock structure is studied for both one- and two-temperature plasmas. The dimensionless ratio of the conductive length to the cooling length determines whether or not conduction is important, and shock jump conditions with conduction are established for a collisionless shock front. Approximate solutions are obtained, with the assumptions that the ionization state of the gas is constant and the cooling rate is a function of temperature alone. In the absence of magnetic fields, these solutions indicate that conduction noticeably influences normal-abundance interstellar shocks with velocities 50-100 km/s and dramatically affects metal-dominated shocks over a wide range of shock velocities.

  12. Pure-oxygen radiative shocks with electron thermal conduction

    Science.gov (United States)

    Borkowski, Kazimierz J.; Shull, J. Michael

    1990-01-01

    Steady state radiative shock models in gas composed entirely of oxygen are calculated with the purpose of explaining observations of fast-moving knots in Cas A and other oxygen-rich SNRs. Models with electron thermal conduction differ significantly from models in which conduction is neglected. Conduction reduces postshock electron temperatures by a factor of 7-10 and flattens temperature gradients. The O III ion, whose forbidden emission usually dominates the observed spectra, is present over a wide range of shock velocities, from 100 to 170 km/s. The electron temperature in the O III forbidden line formation region is 30,000 K, in agreement with the 20,000 K derived from observations. All models with conduction have extensive warm (T above 4000 K) photoionization zones, which provides better agreement with observed optical O I line strengths.

  13. Thermal self-oscillations in radiative heat exchange

    Science.gov (United States)

    Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.

    2015-02-01

    We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO2 and VO2 which exchange heat by thermal radiation in vacuum. The non-linear feedback in the self-oscillating system is provided by metal-insulator transition in VO2. Using the method of fluctuational electrodynamics, we show that under the action of an external laser of a constant power, the temperature of VO2 plate oscillates around its phase transition value. The period and amplitude of oscillations depend on the geometry of the structure. We found that at 500 nm vacuum gap separating bulk SiO2 plate and 50 nm thick VO2 plate, the period of self-oscillations is 2 s and the amplitude is 4 K, which is determined by phase switching at threshold temperatures of phase transition.

  14. Automotive Underhood Thermal Management Analysis Using 3-D Coupled Thermal-Hydrodynamic Computer Models: Thermal Radiation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Pannala, S; D' Azevedo, E; Zacharia, T

    2002-02-26

    The goal of the radiation modeling effort was to develop and implement a radiation algorithm that is fast and accurate for the underhood environment. As part of this CRADA, a net-radiation model was chosen to simulate radiative heat transfer in an underhood of a car. The assumptions (diffuse-gray and uniform radiative properties in each element) reduce the problem tremendously and all the view factors for radiation thermal calculations can be calculated once and for all at the beginning of the simulation. The cost for online integration of heat exchanges due to radiation is found to be less than 15% of the baseline CHAD code and thus very manageable. The off-line view factor calculation is constructed to be very modular and has been completely integrated to read CHAD grid files and the output from this code can be read into the latest version of CHAD. Further integration has to be performed to accomplish the same with STAR-CD. The main outcome of this effort is to obtain a highly scalable and portable simulation capability to model view factors for underhood environment (for e.g. a view factor calculation which took 14 hours on a single processor only took 14 minutes on 64 processors). The code has also been validated using a simple test case where analytical solutions are available. This simulation capability gives underhood designers in the automotive companies the ability to account for thermal radiation - which usually is critical in the underhood environment and also turns out to be one of the most computationally expensive components of underhood simulations. This report starts off with the original work plan as elucidated in the proposal in section B. This is followed by Technical work plan to accomplish the goals of the project in section C. In section D, background to the current work is provided with references to the previous efforts this project leverages on. The results are discussed in section 1E. This report ends with conclusions and future scope of

  15. The surface roughness of (433) Eros as measured by thermal-infrared beaming

    Science.gov (United States)

    Rozitis, B.

    2017-01-01

    In planetary science, surface roughness is regarded to be a measure of surface irregularity at small spatial scales, and causes the thermal-infrared beaming effect (i.e. re-radiation of absorbed sunlight back towards to the Sun). Typically, surface roughness exhibits a degeneracy with thermal inertia when thermophysical models are fitted to disc-integrated thermal-infrared observations of asteroids because of this effect. In this work, it is demonstrated how surface roughness can be constrained for near-Earth asteroid (433) Eros (i.e. the target of NASA's NEAR Shoemaker mission) when using the Advanced Thermophysical Model with thermal-infrared observations taken during an `almost pole-on' illumination and viewing geometry. It is found that the surface roughness of (433) Eros is characterized by an rms slope of 38 ± 8° at the 0.5-cm spatial scale associated with its thermal-infrared beaming effect. This is slightly greater than the rms slope of 25 ± 5° implied by the NEAR Shoemaker laser ranging results when extrapolated to this spatial scale, and indicates that other surface shaping processes might operate, in addition to collisions and gravity, at spatial scales under one metre in order to make asteroid surfaces rougher. For other high-obliquity asteroids observed during `pole-on' illumination conditions, the thermal-infrared beaming effect allows surface roughness to be constrained when the sub-solar latitude is greater than 60°, and if the asteroids are observed at phase angles of less than 40°. They will likely exhibit near-Earth asteroid thermal model beaming parameters that are lower than expected for a typical asteroid at all phase angles up to 100°.

  16. Development of the laser absorption radiation thermometry technique to measure thermal diffusivity in addition to temperature

    Science.gov (United States)

    Levick, Andrew; Lobato, Killian; Edwards, Gordon

    2003-01-01

    A comparative technique based on photothermal radiometry has been developed to measure thermal diffusivity of semi-infinite targets with arbitrary geometry. The technique exploits the principle that the frequency response of the temperature modulation induced by a periodic modulated heating source (in this case a laser spot) scales with thermal diffusivity. To demonstrate this technique, a photothermal radiometer has been developed, which detects modulated thermal radiance at a wavelength of 2 μm due to a small temperature modulation induced on the target surface by a modulated erbium fiber laser of power 1 W. Two frequency responses were measured for platinum and oxidized Inconel 600 targets (the frequency response is a scan of the amplitude of the modulated thermal radiance over laser modulation frequency). Scaling the two responses with respect to frequency gives a ratio of thermal diffusivities Dplatinum/DInconel of 4.45(33) which compares with a literature value of 4.46(50). The aim is to combine this technique with laser absorption radiation thermometry to produce multithermal property instrument for measuring "industrial" targets.

  17. Harmonics radiation of graphene surface plasmon polaritons in terahertz regime

    Science.gov (United States)

    Li, D.; Wang, Y.; Nakajima, M.; Hashida, M.; Wei, Y.; Miyamoto, S.

    2016-06-01

    This letter presents an approach to extract terahertz radiation from surface plasmon polaritons excited in the surface of a uniform graphene structure by an electron beam. A sidewall configuration is proposed to lift the surface plasmon mode to be close to the light line, so that some of its harmonics have chances to go above the light line and become radiative. The harmonics are considered to be excited by a train of periodic electron bunches. The physical mechanism in this scheme is analyzed with three-dimensional theory, and the harmonics excitation and radiation are demonstrated through numerical calculations. The results show that this technique could be an alternative to transform the surface plasmon polaritons into radiation.

  18. Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Phosphor Thermometry

    Science.gov (United States)

    Eldridge, Jeffrey I.

    2016-01-01

    While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness for jet engine components are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. Phosphor thermometry offers several advantages for mapping temperatures of air film cooled surfaces. While infrared thermography has been typically applied to study air film cooling effectiveness, temperature accuracy depends on knowing surface emissivity (which may change) and correcting for effects of reflected radiation. Because decay time-based full-field phosphor thermometry is relatively immune to these effects, it can be applied advantageously to temperature mapping of air film-cooled TBC-coated surfaces. In this presentation, an overview will be given of efforts at NASA Glenn Research Center to perform temperature mapping of air film-cooled TBC-coated surfaces in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and the strengths and limitations of this method for studying air film cooling effectiveness are discussed.

  19. Investigation of thermal effect on exterior wall surface of building material at urban city area

    Directory of Open Access Journals (Sweden)

    Mohd Fadhil Md Din, Hazlini Dzinun, M. Ponraj, Shreeshivadasan Chelliapan, Zainura Zainun Noor, Dilshah Remaz, Kenzo Iwao

    2012-01-01

    Full Text Available This paper describes the investigation of heat impact on the vertical surfaces of buildings based on their thermal behavior. The study was performed based on four building materials that is commonly used in Malaysia; brick, concrete, granite and white concrete tiles. The thermal performances on the building materials were investigated using a surface temperature sensor, data logging system and infrared thermography. Results showed that the brick had the capability to absorb and store heat greater than other materials during the investigation period. The normalized heat (total heat/solar radiation of the brick was 0.093 and produces high heat (51% compared to granite, confirming a substantial amount of heat being released into the atmosphere through radiation and convection. The most sensitive material that absorbs and stores heat was in the following order: brick > concrete > granite > white concrete tiles. It was concluded that the type of exterior wall material used in buildings had significant impact to the environment.

  20. Investigation of thermal effect on exterior wall surface of building material at urban city area

    Energy Technology Data Exchange (ETDEWEB)

    Md Din, Mohd Fadhil; Dzinun, Hazlini; Ponraj, M.; Chelliapan, Shreeshivadasan; Noor, Zainura Zainun [Institute of Environmental Water Resources and Management (IPASA), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Remaz, Dilshah [Faculty of Built Environment, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Iwao, Kenzo [Nagoya Institute of Technology, Nagoya (Japan)

    2012-07-01

    This paper describes the investigation of heat impact on the vertical surfaces of buildings based on their thermal behavior. The study was performed based on four building materials that is commonly used in Malaysia; brick, concrete, granite and white concrete tiles. The thermal performances on the building materials were investigated using a surface temperature sensor, data logging system and infrared thermography. Results showed that the brick had the capability to absorb and store heat greater than other materials during the investigation period. The normalized heat (total heat/solar radiation) of the brick was 0.093 and produces high heat (51% compared to granite), confirming a substantial amount of heat being released into the atmosphere through radiation and convection. The most sensitive material that absorbs and stores heat was in the following order: brick > concrete > granite > white concrete tiles. It was concluded that the type of exterior wall material used in buildings had significant impact to the environment.

  1. Emergent geometry, thermal CFT and surface/state correspondence

    Science.gov (United States)

    Gan, Wen-Cong; Shu, Fu-Wen; Wu, Meng-He

    2017-09-01

    We study a conjectured correspondence between any codimension-two convex surface and a quantum state (SS-duality for short). By applying thermofield double formalism to the SS-duality, we show that thermal geometries naturally emerge as a result of hidden quantum entanglement between two boundary CFTs. We therefore propose a general framework to emerge the thermal geometry from CFT at finite temperature, without knowing many details about the thermal CFT. As an example, the case of 2d CFT is considered. We calculate its information metric and show that it is either BTZ black hole or thermal AdS as expected.

  2. Millimeter radiation from a 3D model of the solar atmosphere I. Diagnosing chromospheric thermal structure

    CERN Document Server

    Loukitcheva, Maria; Carlsson, Mats; White, Stephen

    2015-01-01

    Aims. We use advanced 3D NLTE radiative magnetohydrodynamic simulations of the solar atmosphere to carry out detailed tests of chromospheric diagnostics at millimeter and submillimeter wavelengths. Methods. We focused on the diagnostics of the thermal structure of the chromosphere in the wavelength bands from 0.4 mm up to 9.6 mm that can be accessed with the Atacama Large Millimeter/Submillimeter Array (ALMA) and investigated how these diagnostics are affected by the instrumental resolution. Results. We find that the formation height range of the millimeter radiation depends on the location in the simulation domain and is related to the underlying magnetic structure. Nonetheless, the brightness temperature is a reasonable measure of the gas temperature at the effective formation height at a given location on the solar surface. There is considerable scatter in this relationship, but this is significantly reduced when very weak magnetic fields are avoided. Our results indicate that although instrumental smearin...

  3. Second Law Analysis for Variable Viscosity Hydromagnetic Boundary Layer Flow with Thermal Radiation and Newtonian Heating

    Directory of Open Access Journals (Sweden)

    Oluwole Daniel Makinde

    2011-08-01

    Full Text Available The present paper is concerned with the analysis of inherent irreversibility in hydromagnetic boundary layer flow of variable viscosity fluid over a semi-infinite flat plate under the influence of thermal radiation and Newtonian heating. Using local similarity solution technique and shooting quadrature, the velocity and temperature profiles are obtained numerically and utilized to compute the entropy generation number. The effects of magnetic field parameter, Brinkmann number, the Prandtl number, variable viscosity parameter, radiation parameter and local Biot number on the fluid velocity profiles, temperature profiles, local skin friction and local Nusselt number are presented. The influences of the same parameters and the dimensionless group parameter on the entropy generation rate in the flow regime and Bejan number are calculated, depicted graphically and discussed quantitatively. It is observed that the peak of entropy generation rate is attained within the boundary layer region and plate surface act as a strong source of entropy generation and heat transfer irreversibility.

  4. The Surface Roughness of (433) Eros as Measured by Thermal-Infrared Beaming

    CERN Document Server

    Rozitis, Ben

    2016-01-01

    In planetary science, surface roughness is regarded to be a measure of surface irregularity at small spatial scales, and causes the thermal-infrared beaming effect (i.e. re-radiation of absorbed sunlight back towards to the Sun). Typically, surface roughness exhibits a degeneracy with thermal inertia when thermophysical models are fitted to disc-integrated thermal-infrared observations of asteroids because of this effect. In this work, it is demonstrated how surface roughness can be constrained for near-Earth asteroid (433) Eros (i.e. the target of NASA's NEAR Shoemaker mission) when using the Advanced Thermophysical Model with thermal-infrared observations taken during an "almost pole-on" illumination and viewing geometry. It is found that the surface roughness of (433) Eros is characterised by an RMS slope of 38 $\\pm$ 8{\\deg} at the 0.5-cm spatial scale associated with its thermal-infrared beaming effect. This is slightly greater than the RMS slope of 25 $\\pm$ 5{\\deg} implied by the NEAR Shoemaker laser ran...

  5. Thermal annealing of natural, radiation-damaged pyrochlore

    Energy Technology Data Exchange (ETDEWEB)

    Zietlow, Peter; Mihailova, Boriana [Hamburg Univ. (Germany). Dept. of Earth Sciences; Beirau, Tobias [Hamburg Univ. (Germany). Dept. of Earth Sciences; Stanford Univ., CA (United States). Dept. of Geological Sciences; and others

    2017-03-01

    Radiation damage in minerals is caused by the α-decay of incorporated radionuclides, such as U and Th and their decay products. The effect of thermal annealing (400-1000 K) on radiation-damaged pyrochlores has been investigated by Raman scattering, X-ray powder diffraction (XRD), and combined differential scanning calorimetry/thermogravimetry (DSC/TG). The analysis of three natural radiation-damaged pyrochlore samples from Miass/Russia [6.4 wt% Th, 23.1.10{sup 18} α-decay events per gram (dpg)], Panda Hill/Tanzania (1.6 wt% Th, 1.6.10{sup 18} dpg), and Blue River/Canada (10.5 wt% U, 115.4.10{sup 18} dpg), are compared with a crystalline reference pyrochlore from Schelingen (Germany). The type of structural recovery depends on the initial degree of radiation damage (Panda Hill 28%, Blue River 85% and Miass 100% according to XRD), as the recrystallization temperature increases with increasing degree of amorphization. Raman spectra indicate reordering on the local scale during annealing-induced recrystallization. As Raman modes around 800 cm{sup -1} are sensitive to radiation damage (M. T. Vandenborre, E. Husson, Comparison of the force field in various pyrochlore families. I. The A{sub 2}B{sub 2}O{sub 7} oxides. J. Solid State Chem. 1983, 50, 362, S. Moll, G. Sattonnay, L. Thome, J. Jagielski, C. Decorse, P. Simon, I. Monnet, W. J. Weber, Irradiation damage in Gd{sub 2}Ti{sub 2}O{sub 7} single crystals: Ballistic versus ionization processes. Phys. Rev. 2011, 84, 64115.), the degree of local order was deduced from the ratio of the integrated intensities of the sum of the Raman bands between 605 and 680 cm{sup -1} divided by the sum of the integrated intensities of the bands between 810 and 860 cm{sup -1}. The most radiation damaged pyrochlore (Miass) shows an abrupt recovery of both, its short- (Raman) and long-range order (X-ray) between 800 and 850 K, while the weakly damaged pyrochlore (Panda Hill) begins to recover at considerably lower temperatures (near 500 K

  6. Decorative Surfaces Obtained through Thermal Zyncking

    Directory of Open Access Journals (Sweden)

    Tamara Radu

    2010-06-01

    Full Text Available The surface morphology of the galvanized sheets is formed after the solidification of the melted metal, carried along the carrier strap during its extraction from the zinc bath. The surface layer quality depends on the fluidity of the melting, on its superficial tension and on the solidification characteristics, according to the chemical composition of the melting. The elements of micro-alloys can improve the surface of galvanized steel with qualities such as: uniformity, texture, luminosity. Depending on the combination elements of micro-alloying the surface can have different types of metallic layers with an important effect on the coating morphology. The research we made revealed the important effect it had for alloys with Al, Sn, Bi, Pb on the coating layer morphology.

  7. Relationships between surface solar radiation and wheat yield in Spain

    Science.gov (United States)

    Hernandez-Barrera, Sara; Rodriguez-Puebla, Concepción

    2017-04-01

    Here we examine the role of solar radiation to describe wheat-yield variability in Spain. We used Partial Least Square regression to capture the modes of surface solar radiation that drive wheat-yield variability. We will show that surface solar radiation introduces the effects of teleconnection patterns on wheat yield and also it is associated with drought and diurnal temperature range. We highlight the importance of surface solar radiation to obtain models for wheat-yield projections because it could reduce uncertainty with respect to the projections based on temperatures and precipitation variables. In addition, the significance of the model based on surface solar radiation is greater than the previous one based on drought and diurnal temperature range (Hernandez-Barrera et al., 2016). According to our results, the increase of solar radiation over Spain for 21st century could force a wheat-yield decrease (Hernandez-Barrera et al., 2017). Hernandez-Barrera S., Rodríguez-Puebla C. and Challinor A.J. 2016 Effects of diurnal temperature range and drought on wheat yield in Spain. Theoretical and Applied Climatology. DOI: 10.1007/s00704-016-1779-9 Hernandez-Barrera S., Rodríguez-Puebla C. 2017 Wheat yield in Spain and associated solar radiation patterns. International Journal of Climatology. DOI: 10.1002/joc.4975

  8. [Relationship between surface UV radiation and air pollution in Beijing].

    Science.gov (United States)

    An, Jun-lin; Wang, Yue-si; Li, Xin; Sun, Yang; Shen, Shuang-he

    2008-04-01

    Based on the data of solar radiation and air pollutants collected in Beijing, the relationship between surface ultraviolet (UV) radiation and the content of air pollutants were analyzed, using the radiative transfer model TUV4.4 (Tropospheric Ultraviolet Visible). The results show that average total ozone content is 329 DU and higher in winter and spring, lower in summer and autumn. The inverse relationship exists between ground level UV radiation and total ozone content. This study also shows that a substantial reduction (up to 50%) in the UV radiation on days with high levels of air pollution. Larger fluctuations are found in UV radiation in the summer. The effects of clouds and air pollution on UV are higher than on total solar radiation, and the reduction in UV is about twice as large as the total solar radiation values. Strong reduction in the UV radiation reaching the ground is associated with the increase of tropospheric ozone and nitrogen oxides in Beijing. The correlation coefficient between ozone concentration and decrease in UV radiation is 0.70 in the early afternoon.

  9. Ground-based measurement of surface temperature and thermal emissivity

    Science.gov (United States)

    Owe, M.; Van De Griend, A. A.

    1994-01-01

    Motorized cable systems for transporting infrared thermometers have been used successfully during several international field campaigns. Systems may be configured with as many as four thermal sensors up to 9 m above the surface, and traverse a 30 m transect. Ground and canopy temperatures are important for solving the surface energy balance. The spatial variability of surface temperature is often great, so that averaged point measurements result in highly inaccurate areal estimates. The cable systems are ideal for quantifying both temporal and spatial variabilities. Thermal emissivity is also necessary for deriving the absolute physical temperature, and measurements may be made with a portable measuring box.

  10. Hawking non-thermal and Purely thermal radiations of Kerr-de Sitter black hole by Hamilton-Jacobi method

    CERN Document Server

    Hossain, M Ilias

    2013-01-01

    Incorporating Parikh and Wilczek's opinion to the Kerr de-Sitter (KdS) black hole Hawking non-thermal and purely thermal radiations have been investigated using Hamilton-Jacobi method. We have taken the background spacetime of KdS black hole as dynamical, involving the self-gravitation effect of the emitted particles, energy and angular momentum has been taken as conserved and show that the tunneling rate is related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The explored results gives a correction to the Hawking radiation of KdS black hole.

  11. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp; Nishikawa, Kazutaka; Iizuka, Hideo [Toyota Central Research and Development Labs, Nagakute, Aichi 480-1192 (Japan)

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  12. Universal modal radiation laws for all thermal emitters.

    Science.gov (United States)

    Miller, David A B; Zhu, Linxiao; Fan, Shanhui

    2017-04-25

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

  13. The Remote Sensing of Surface Radiative Temperature over Barbados.

    Science.gov (United States)

    remote sensing of surface radiative temperature over Barbados was undertaken using a PRT-5 attached to a light aircraft. Traverses across the centre of the island, over the rugged east coast area, and the urban area of Bridgetown were undertaken at different times of day and night in the last week of June and the first week of December, 1969. These traverses show that surface variations in long-wave radiation emission lie within plus or minus 5% of the observations over grass at a representative site. The quick response of the surface to sunset and sunrise was

  14. Transient radiative heat transfer in an inhomogeneous participating medium with Fresnel's surfaces

    Institute of Scientific and Technical Information of China (English)

    YI HongLiang; TAN HePing

    2008-01-01

    This paper studies the radiative heat transfer within an inhomogeneous and isot-ropically scattering medium with reflecting Fresnel's surfaces. Thermal radiation transfers in a curve inside a medium with an inhomogeneous distribution of a re-fractive index. The inhomogenous medium is divided into n homogenous isother-mal sub-layers and in each sub-layer the radiation transfers in a straight line. By adopting a multilayer radiative transfer model and using a ray-tracing/nodal-ana-lyzing method, a radiative transfer model is built for the inhomogenous participat-ing medium. In the muItilayer model, a criterion for refraction / total reflection at the interfaces between neighboring sub-layers is introduced, avoiding the integral singularity and reflection at physically inexistent interfaces (only the total reflection is considered). Transient thermal behavior is examined when the parameters of the radiative properties such as refractive indexes, extinction coefficients, and sin-gle-scattering albedoes vary continually along the thickness direction.

  15. On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

    Directory of Open Access Journals (Sweden)

    S. Otto

    2010-11-01

    Full Text Available Realistic size equivalence and shape of Saharan mineral dust particles are derived from on in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006, dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10%. At the bottom of the atmosphere (BOA the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal forcing by 55/5% at the TOA over ocean/land and 15% at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20%. Large dust particles significantly contribute to all the radiative effects reported.

  16. Thermal electromagnetic radiation in heavy-ion collisions

    Science.gov (United States)

    Rapp, R.; van Hees, H.

    2016-08-01

    We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator ( ρ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to a) the fireball lifetime through the dilepton yield in the low invariant-mass window 0.3 GeV ≤ M ≤ 0.7 GeV, and b) the early temperatures of the fireball through the slope of the invariant-mass spectrum in the intermediate-mass region (1.5 GeV < M < 2.5 GeV). The investigation of the pertinent excitation function suggests that the beam energies provided by the NICA and FAIR projects are in a promising range for a potential discovery of the onset of a first-order phase transition, as signaled by a non-monotonous behavior of both low-mass yields and temperature slopes.

  17. Thermal electromagnetic radiation in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R. [Texas A and M University, Cyclotron Institute and Department of Physics and Astronomy, College Station, TX (United States); Hees, H. van [Goethe-Universitaet Frankfurt, Institut fuer Theoretische Physik, Frankfurt (Germany); Frankfurt Institute of Advanced Studies (FIAS), Frankfurt (Germany)

    2016-08-15

    We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator (ρ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to (a) the fireball lifetime through the dilepton yield in the low invariant-mass window 0.3 GeV ≤ M ≤ 0.7 GeV, and (b) the early temperatures of the fireball through the slope of the invariant-mass spectrum in the intermediate-mass region (1.5 GeV < M < 2.5 GeV). The investigation of the pertinent excitation function suggests that the beam energies provided by the NICA and FAIR projects are in a promising range for a potential discovery of the onset of a first-order phase transition, as signaled by a non-monotonous behavior of both low-mass yields and temperature slopes. (orig.)

  18. Thermal Electromagnetic Radiation in Heavy-Ion Collisions

    CERN Document Server

    Rapp, R

    2016-01-01

    We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator ($\\rho$ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to (a) the fireball lifetime through the dilepton yield in the low invariant-mass window $0.3 \\; \\mathrm{GeV} \\leq M \\leq 0.7 \\; \\mathrm{GeV}$, and (b) the early temperatures of the fireball through th...

  19. Hawking Non-thermal and Thermal Radiations of Schwarzschild Anti-de Sitter Black Hole by Hamilton-Jacobi method

    CERN Document Server

    Rahman, M Atiqur

    2013-01-01

    The massive particles tunneling method has been used to investigate the Hawking non-thermal and purely thermal radiations of Schwarzschild Anti-de Sitter (SAdS) black hole. Considering the spacetime background to be dynamical, incorporate the self-gravitation effect of the emitted particles the imaginary part of the action has been derived from Hamilton-Jacobi equation. Using the conservation laws of energy and angular momentum we have showed that the non-thermal and purely thermal tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The result obtained for SAdS black hole is also in accordance with Parikh and Wilczek\\rq s opinion and gives a correction to the Hawking radiation of SAdS black hole.

  20. Hawking non-thermal and thermal radiations of Schwarzschild anti-de Sitter black hole by Hamilton-Jacobi method

    Science.gov (United States)

    Rahman, M. Atiqur; Hossain, M. Ilias

    2013-06-01

    The massive particles tunneling method has been used to investigate the Hawking non-thermal and purely thermal radiations of Schwarzschild Anti-de Sitter (SAdS) black hole. Considering the spacetime background to be dynamical, incorporate the self-gravitation effect of the emitted particles the imaginary part of the action has been derived from Hamilton-Jacobi equation. Using the conservation laws of energy and angular momentum we have showed that the non-thermal and purely thermal tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The result obtained for SAdS black hole is also in accordance with Parikh and Wilczek's opinion and gives a correction to the Hawking radiation of SAdS black hole.

  1. External Thermal Insulation Composite Systems: Critical Parameters for Surface Hygrothermal Behaviour

    Directory of Open Access Journals (Sweden)

    Eva Barreira

    2014-01-01

    Full Text Available External Thermal Insulation Composite Systems (ETICS are often used in Europe. Despite its thermal advantages, low cost, and ease of application, this system has serious problems of biological growth causing the cladding defacement. Recent studies pointed that biological growth is due to high values of surface moisture content, which mostly results from the combined effect of exterior surface condensation, wind-driven rain, and drying process. Based on numerical simulation, this paper points the most critical parameters involved in hygrothermal behaviour of ETICS, considering the influence of thermal and hygric properties of the external rendering, the effect of the characteristics of the façade, and the consequences of the exterior and interior climate on exterior surface condensation, wind-driven rain, and drying process. The model used was previously validated by comparison with the results of an “in situ” campaign. The results of the sensitivity analyses show that relative humidity and temperature of the exterior air, atmospheric radiation, and emissivity of the exterior rendering are the parameters that most influence exterior surface condensation. Wind-driven rain depends mostly on horizontal rain, building’s height, wind velocity, and orientation. The drying capacity is influenced by short-wave absorbance, incident solar radiation, and orientation.

  2. Stellar and Extragalactic Radiation at the Earth’s Surface

    Indian Academy of Sciences (India)

    Jean-Claude Pecker; Jayant V. Narlikar

    2006-03-01

    Reviving a calculation made by Eddington in the 1920s, and using the most recent and comprehensive databases available on stars and galaxies, including more than 2,500,000 stars and around 20,000 galaxies we have computed their total radiation received at the Earth just outside its atmosphere. This radiation density, if thermalized, would be equivalent to a temperature of 4.212 K. The comparability of this temperature to that of the cosmic microwave background (2.723 K) may either be a pure coincidence or may hold a key to some as yet unknown, aspect of the universe.

  3. Radiative transfer modeling of surface chemical deposits

    Science.gov (United States)

    Reichardt, Thomas A.; Kulp, Thomas J.

    2016-05-01

    Remote detection of a surface-bound chemical relies on the recognition of a pattern, or "signature," that is distinct from the background. Such signatures are a function of a chemical's fundamental optical properties, but also depend upon its specific morphology. Importantly, the same chemical can exhibit vastly different signatures depending on the size of particles composing the deposit. We present a parameterized model to account for such morphological effects on surface-deposited chemical signatures. This model leverages computational tools developed within the planetary and atmospheric science communities, beginning with T-matrix and ray-tracing approaches for evaluating the scattering and extinction properties of individual particles based on their size and shape, and the complex refractive index of the material itself. These individual-particle properties then serve as input to the Ambartsumian invariant imbedding solution for the reflectance of a particulate surface composed of these particles. The inputs to the model include parameters associated with a functionalized form of the particle size distribution (PSD) as well as parameters associated with the particle packing density and surface roughness. The model is numerically inverted via Sandia's Dakota package, optimizing agreement between modeled and measured reflectance spectra, which we demonstrate on data acquired on five size-selected silica powders over the 4-16 μm wavelength range. Agreements between modeled and measured reflectance spectra are assessed, while the optimized PSDs resulting from the spectral fitting are then compared to PSD data acquired from independent particle size measurements.

  4. Radiative Transfer Model for Contaminated Rough Surfaces

    Science.gov (United States)

    2013-02-01

    plot of Figure 8 shows three sharp spectral features (in the LWIR region) that were used for calibration . 1000 1500 2000 2500 3000 3500 0 0.1 0.2...transfer, reflectance, rough surface, BRDF, Kramers-Kronig, penetration depth, fill factor, infrared, LWIR , MWIR, absorption coefficient, scattering...and the calibrated α are plotted in red, and green, respectively

  5. The effects of thermal radiation and viscous dissipation on MHD heat and mass diffusion flow past an oscillating vertical plate embedded in a porous medium with variable surface conditions

    Directory of Open Access Journals (Sweden)

    Kishore P.M.

    2012-01-01

    Full Text Available This investigation is undertaken to study the hydromagnetic flow of a viscous incompressible fluid past an oscillating vertical plate embedded in a porous medium with radiation, viscous dissipation and variable heat and mass diffusion. Governing equations are solved by unconditionally stable explicit finite difference method of DuFort - Frankel’s type for concentration, temperature, vertical velocity field and skin - friction and they are presented graphically for different values of physical parameters involved. It is observed that plate oscillation, variable mass diffusion, radiation, viscous dissipation and porous medium affect the flow pattern significantly.

  6. 3D SURFACE GENERATION FROM AERIAL THERMAL IMAGERY

    Directory of Open Access Journals (Sweden)

    B. Khodaei

    2015-12-01

    Full Text Available Aerial thermal imagery has been recently applied to quantitative analysis of several scenes. For the mapping purpose based on aerial thermal imagery, high accuracy photogrammetric process is necessary. However, due to low geometric resolution and low contrast of thermal imaging sensors, there are some challenges in precise 3D measurement of objects. In this paper the potential of thermal video in 3D surface generation is evaluated. In the pre-processing step, thermal camera is geometrically calibrated using a calibration grid based on emissivity differences between the background and the targets. Then, Digital Surface Model (DSM generation from thermal video imagery is performed in four steps. Initially, frames are extracted from video, then tie points are generated by Scale-Invariant Feature Transform (SIFT algorithm. Bundle adjustment is then applied and the camera position and orientation parameters are determined. Finally, multi-resolution dense image matching algorithm is used to create 3D point cloud of the scene. Potential of the proposed method is evaluated based on thermal imaging cover an industrial area. The thermal camera has 640×480 Uncooled Focal Plane Array (UFPA sensor, equipped with a 25 mm lens which mounted in the Unmanned Aerial Vehicle (UAV. The obtained results show the comparable accuracy of 3D model generated based on thermal images with respect to DSM generated from visible images, however thermal based DSM is somehow smoother with lower level of texture. Comparing the generated DSM with the 9 measured GCPs in the area shows the Root Mean Square Error (RMSE value is smaller than 5 decimetres in both X and Y directions and 1.6 meters for the Z direction.

  7. Near-field radiative thermal control with graphene covered on different materials

    Science.gov (United States)

    Wang, Ao; Zheng, Zhiheng; Xuan, Yimin

    2016-09-01

    Based on the structure of double-layer parallel plates, this paper demonstrates that thermal radiation in near field is greatly enhanced due to near-field effects, exceeding Planck‧s blackbody radiation law. To study the effect of graphene on thermal radiation in near field, the authors add graphene layer into the structure and analyze the ability of graphene to control near-field thermal radiation with different materials. The result indicates that the graphene layer effectively suppresses the near-field thermal radiation between metal plates or polar-dielectric plates, having good ability of thermal insulation. But for doped-silicon plates, depending on the specific models, graphene has different control abilities, suppressing or enhancing, and the control abilities mainly depend on the material graphene is attached to. The authors also summarize some common rules about the different abilities of graphene to control the near-field thermal radiation. In consideration of the thickness of 0.34 nm of monolayer graphene, this paper points out that graphene plays a very important role in controlling the near-field thermal radiation.

  8. Drop formation by thermal fluctuations at an ultralow surface tension.

    Science.gov (United States)

    Hennequin, Y; Aarts, D G A L; van der Wiel, J H; Wegdam, G; Eggers, J; Lekkerkerker, H N W; Bonn, Daniel

    2006-12-15

    We present experimental evidence that drop breakup is caused by thermal noise in a system with a surface tension that is more than 10(6) times smaller than that of water. We observe that at very small scales classical hydrodynamics breaks down and the characteristic signatures of pinch-off due to thermal noise are observed. Surprisingly, the noise makes the drop size distribution more uniform, by suppressing the formation of satellite droplets of the smallest sizes. The crossover between deterministic hydrodynamic motion and stochastic thermally driven motion has repercussions for our understanding of small-scale hydrodynamics, important in many problems such as micro- or nanofluidics and interfacial singularities.

  9. Ground Plane and Near-Surface Thermal Analysis for NASA's Constellation Program

    Science.gov (United States)

    Gasbarre, Joseph F.; Amundsen, Ruth M.; Scola, Salvatore; Leahy, Frank F.; Sharp, John R.

    2008-01-01

    Most spacecraft thermal analysis tools assume that the spacecraft is in orbit around a planet and are designed to calculate solar and planetary fluxes, as well as radiation to space. On NASA Constellation projects, thermal analysts are also building models of vehicles in their pre-launch condition on the surface of a planet. This process entails making some modifications in the building and execution of a thermal model such that the radiation from the planet, both reflected albedo and infrared, is calculated correctly. Also important in the calculation of pre-launch vehicle temperatures are the natural environments at the vehicle site, including air and ground temperatures, sky radiative background temperature, solar flux, and optical properties of the ground around the vehicle. A group of Constellation projects have collaborated on developing a cohesive, integrated set of natural environments that accurately capture worst-case thermal scenarios for the pre-launch and launch phases of these vehicles. The paper will discuss the standardization of methods for local planet modeling across Constellation projects, as well as the collection and consolidation of natural environments for launch sites. Methods for Earth as well as lunar sites will be discussed.

  10. The radiation of surface wave energy: Implications for volcanic tremor

    Science.gov (United States)

    Haney, M. M.; Denolle, M.; Lyons, J. J.; Nakahara, H.

    2015-12-01

    The seismic energy radiated by active volcanism is one common measurement of eruption size. For example, the magnitudes of individual earthquakes in volcano-tectonic (VT) swarms can be summed and expressed in terms of cumulative magnitude, energy, or moment release. However, discrepancies exist in current practice when treating the radiated energy of volcano seismicity dominated by surface waves. This has implications for volcanic tremor, since eruption tremor typically originates at shallow depth and is made up of surface waves. In the absence of a method to compute surface wave energy, estimates of eruption energy partitioning between acoustic and seismic waves typically assume seismic energy is composed of body waves. Furthermore, without the proper treatment of surface wave energy, it is unclear how much volcanic tremor contributes to the overall seismic energy budget during volcanic unrest. To address this issue, we derive, from first principles, the expression of surface wave radiated energy. In contrast with body waves, the surface wave energy equation is naturally expressed in the frequency domain instead of the time domain. We validate our result by reproducing an analytical solution for the radiated power of a vertical force source acting on a free surface. We further show that the surface wave energy equation leads to an explicit relationship between energy and the imaginary part of the surface wave Green's tensor at the source location, a fundamental property recognized within the field of seismic interferometry. With the new surface wave energy equation, we make clear connections to reduced displacement and propose an improved formula for the calculation of surface wave reduced displacement involving integration over the frequency band of tremor. As an alternative to reduced displacement, we show that reduced particle velocity squared is also a valid physical measure of tremor size, one based on seismic energy rate instead of seismic moment rate. These

  11. Local thermal properties of the surface of Vesta

    Science.gov (United States)

    Capria, M. T.; Tosi, F.; Capaccioni, F.; De Sanctis, M. C.; Palomba, E.; Ammannito, E.; Carraro, F.; Fonte, S.; Titus, T. N.; Combe, J.-P.; Toplis, M.; Sunshine, J.; Fulchignoni, M.; Russel, C. T.; Raymond, C. A.

    2012-04-01

    Temperature information has been obtained from the Dawn/VIR (Visible InfraRed imaging spectrometer) spectra acquired during the Vesta campaign. When combined with a thermophysical model, these temperatures can be used to derive surface thermal properties. Thermal properties are sensitive to several physical characteristics of the surface that are not all spatially resolved. Thus, the derivation of surface temperatures and thermal inertia can lead to the characterization of surface and sub-surface properties of Vesta and the determination of regolith properties. The model we are using solves the heat conduction equation and provide the temperature as a function of thermal conductivity, albedo, emissivity, density and specific heat. The model is applied to the actual shape of Vesta: for any given location, characterized by a well-defined illumination condition and a given UTC time to compute the thermal inertia that results in model temperatures providing a best-fit to surface temperatures as retrieved by VIR. The model has been already applied to the first Vesta full-disk data to derive the global average thermal inertia of Vesta. The values obtained are typical of fine-grained, unconsolidated materials (i.e. dust) and suggest a surface in which a dust layer is wide-spread on coarser regolith. The model is now being applied on small regions of the surface of Vesta. Specific regions are selected because they are interesting for some reason or appear different from the surroundings, such as, for example, dark and bright spots and other peculiar features. Given a location, the thermophysical code is applied until the obtained temperatures are matching (best-fit techniques are used) the temperatures derived from the VIR spectra. The thermal inertia, thermal conductivity, albedo and roughness values are then assumed to be characterizing the location under analysis. The results of the model must be carefully checked and interpreted by taking into account the context (from

  12. Mathematical modeling of temperature mapping over skin surface and its implementation in thermal disease diagnostics.

    Science.gov (United States)

    Deng, Zhong-Shan; Liu, Jing

    2004-09-01

    In non-invasive thermal diagnostics, accurate correlations between the thermal image on skin surface and interior human pathophysiology are often desired, which require general solutions for the bioheat equation. In this study, the Monte Carlo method was implemented to solve the transient three-dimensional bio-heat transfer problem with non-linear boundary conditions (simultaneously with convection, radiation and evaporation) and space-dependent thermal physiological parameters. Detailed computations indicated that the thermal states of biological bodies, reflecting physiological conditions, could be correlated to the temperature or heat flux mapping recorded at the skin surface. The effect of the skin emissivity and humidity, the convective heat transfer coefficient, the relative humidity and temperature of the surrounding air, the metabolic rate and blood perfusion rate in the tumor, and the tumor size and number on the sensitivity of thermography are comprehensively investigated. Moreover, several thermal criteria for disease diagnostic were proposed based on statistical principles. Implementations of this study for the clinical thermal diagnostics are discussed.

  13. Enhancement and tunability of near-field radiative heat transfer mediated by surface plasmon polaritons in thin plasmonic films

    CERN Document Server

    Boriskina, Svetlana V; Huang, Yi; Zhou, Jiawei; Chiloyan, Vazrik; Chen, Gang

    2016-01-01

    The properties of thermal radiation exchange between hot and cold objects can be strongly modified if they interact in the near field where electromagnetic coupling occurs across gaps narrower than the dominant wavelength of thermal radiation. Using a rigorous fluctuational electrodynamics approach, we predict that ultra-thin films of plasmonic materials can be used to dramatically enhance near-field heat transfer. The total spectrally integrated film-to-film heat transfer is over an order of magnitude larger than between the same materials in bulk form and also exceeds the levels achievable with polar dielectrics such as SiC. We attribute this enhancement to the significant spectral broadening of radiative heat transfer due to coupling between surface plasmon polaritons (SPPs) on both sides of each thin film. We show that the radiative heat flux spectrum can be further shaped by the choice of the substrate onto which the thin film is deposited. In particular, substrates supporting surface phonon polaritons (...

  14. Influence of thermal radiation and Joule heating in the Eyring-Powell fluid flow with the Soret and Dufour effects

    Science.gov (United States)

    Hayat, T.; Ali, Sh.; Alsaedi, A.; Alsulami, H. H.

    2016-11-01

    A two-dimensional magnetohydrodynamic boundary layer flow of the Eyring-Powell fluid on a stretching surface in the presence of thermal radiation and Joule heating is analyzed. The Soret and Dufour effects are taken into account. Partial differential equations are reduced to a system of ordinary differential equations, and series solutions of the resulting system are derived. Velocity, temperature, and concentration profiles are obtained. The skin friction coefficient and the local Nusselt and Sherwood numbers are computed and analyzed.

  15. Experimental and CFD analyses of a thermal radiation shield dimple plate for cryogenic pump application

    Science.gov (United States)

    Scannapiego, M.; Day, C.

    2015-12-01

    Large customized cryogenic pumps are used in fusion reactors to evacuate the plasma exhaust from the torus. Cryopumps usually consist of an active pumping surface area cooled below 5 K and shielded from direct outer thermal radiation by plates cooled at 80K. In nuclear fusion applications, cryopumps are exposed to excessively high heat fluxes during pumping operation, and follow-up regeneration cycles with rapid warm-up and cool-down phases. Therefore, high cryogenic operational mass flows are required and thus pressure drop and heat transfer characteristics become key issues for the design of the pump cryogenic circuits. Actively cooled dimple plates are a preferred design solution for the thermal radiation shield. A test plate with a rhomb pattern of dimples has been manufactured and tested in terms of pressure drop with a dedicated test facility using water. In the present work, computational fluid dynamics (CFD) models of the test dimple plate have been performed, and computed pressure drops have been compared to experimental results. Despite the complexity of the geometry, a good agreement with the experimental results was found. Then, the validated CFD approach has been further extended to relevant operation conditions, using gaseous helium at cryogenic temperature as working fluid. The resulting pressure drop and heat transfer characteristics are finally presented.

  16. Surface Structure in an Accretion Disk Annulus with Comparable Radiation and Gas Pressure

    CERN Document Server

    Blaes, Omer; Krolik, Julian H

    2007-01-01

    We have employed a 3-d energy-conserving radiation MHD code to simulate the vertical structure and thermodynamics of a shearing box whose parameters were chosen so that the radiation and gas pressures would be comparable. The upper layers of this disk segment are magnetically-dominated, creating conditions appropriate for both photon bubble and Parker instabilities. We find little evidence for photon bubbles, even though the simulation has enough spatial resolution to see them and their predicted growth rates are high. On the other hand, there is strong evidence for Parker instabilities, and they appear to dominate the evolution of the magnetically supported surface layers. The disk photosphere is complex, with large density inhomogeneities at both the scattering and effective (thermalization) photospheres of the evolving horizontally-averaged structure. Both the dominant magnetic support and the inhomogeneities are likely to have strong effects on the spectrum and polarization of thermal photons emerging fro...

  17. Thermal discrete dipole approximation for the description of thermal emission and radiative heat transfer of magneto-optical systems

    Science.gov (United States)

    Abraham Ekeroth, R. M.; García-Martín, A.; Cuevas, J. C.

    2017-06-01

    We present here a generalization of the thermal discrete dipole approximation (TDDA) that allows us to describe the near-field radiative heat transfer between finite objects of arbitrary shape that exhibit magneto-optical (MO) activity. We also extend the TDDA approach to describe the thermal emission of a finite object with and without MO activity. Our method is also valid for optically anisotropic materials described by an arbitrary permittivity tensor and we provide simple closed formulas for the basic thermal quantities that considerably simplify the implementation of the TDDA method. Moreover, we show that by employing our TDDA approach one can rigorously demonstrate Kirchhoff's radiation law relating the emissivity and absorptivity of an arbitrary MO object. Our work paves the way for the theoretical study of the active control of emission and radiative heat transfer between MO systems of arbitrary size and shape.

  18. Surface dose with grids in electron beam radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, K.-H.; Huang, C.-Y.; Lin, J.-P.; Chu, T.-C. E-mail: tcchu@mx.nthu.edu.tw

    2002-03-01

    This investigation attempts to solve the problem of the lack of skin-sparing effect in electron radiation therapy and to increase the tolerance of skin to radiation using the grid technique. Electron grid therapy involves the mounting of a Cerrobend grid in the electron cone. Film dosimetry was employed to measure the relative surface dose and the percentage depth dose profile of electron grid portals. Various grid hole diameters (d=0.45, 1.0, 1.5 cm) and grid hole spacings (s=0.4, 0.2 cm) were considered for electron beams from 6 to 14 MeV. Experimental results indicate that the electron grid technique can reduce the relative surface dose in electron radiation therapy. Degradations of the relative surface dose depend on the percentage of open area in the grid portal. A proper grid design allows the surface dose to be reduced and the range of nonhomogeneous doses to be limited to a depth at which the target volume can receive a homogeneous dose. The grid technique can lower the surface dose in electron radiation therapy.

  19. Assessing thermal conductivity of composting reactor with attention on varying thermal resistance between compost and the inner surface.

    Science.gov (United States)

    Wang, Yongjiang; Niu, Wenjuan; Ai, Ping

    2016-12-01

    Dynamic estimation of heat transfer through composting reactor wall was crucial for insulating design and maintaining a sanitary temperature. A model, incorporating conductive, convective and radiative heat transfer mechanisms, was developed in this paper to provide thermal resistance calculations for composting reactor wall. The mechanism of thermal transfer from compost to inner surface of structural layer, as a first step of heat loss, was important for improving insulation performance, which was divided into conduction and convection and discussed specifically in this study. It was found decreasing conductive resistance was responsible for the drop of insulation between compost and reactor wall. Increasing compost porosity or manufacturing a curved surface, decreasing the contact area of compost and the reactor wall, might improve the insulation performance. Upon modeling of heat transfers from compost to ambient environment, the study yielded a condensed and simplified model that could be used to conduct thermal resistance analysis for composting reactor. With theoretical derivations and a case application, the model was applicable for both dynamic estimation and typical composting scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. An inverse method for flue gas shielded metal surface temperature measurement based on infrared radiation

    Science.gov (United States)

    Zhang, B.; Xu, C. L.; Wang, S. M.

    2016-07-01

    The infrared temperature measurement technique has been applied in various fields, such as thermal efficiency analysis, environmental monitoring, industrial facility inspections, and remote temperature sensing. In the problem of infrared measurement of the metal surface temperature of superheater surfaces, the outer wall of the metal pipe is covered by radiative participating flue gas. This means that the traditional infrared measurement technique will lead to intolerable measurement errors due to the absorption and scattering of the flue gas. In this paper, an infrared measurement method for a metal surface in flue gas is investigated theoretically and experimentally. The spectral emissivity of the metal surface, and the spectral absorption and scattering coefficients of the radiative participating flue gas are retrieved simultaneously using an inverse method called quantum particle swarm optimization. Meanwhile, the detected radiation energy simulated using a forward simulation method (named the source multi-flux method) is set as the input of the retrieval. Then, the temperature of the metal surface detected by an infrared CCD camera is modified using the source multi-flux method in combination with these retrieved physical properties. Finally, an infrared measurement system for metal surface temperature is built to assess the proposed method. Experimental results show that the modified temperature is closer to the true value than that of the direct measured temperature.

  1. Near-field radiative heat transfer between arbitrarily-shaped objects and a surface

    CERN Document Server

    Edalatpour, Sheila

    2016-01-01

    A fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented. The surface interactions are treated analytically via Sommerfeld's theory of electric dipole radiation above an infinite plane. The volume integral equation for the electric field is discretized using the thermal discrete dipole approximation (T-DDA). The framework is verified against exact results in the sphere-surface configuration, and is applied to analyze near-field radiative heat transfer between a complex-shaped probe and an infinite plane both made of silica. It is found that when the probe tip size is approximately equal to or smaller than the gap d separating the probe and the surface, coupled localized surface phonon (LSPh)-surface phonon-polariton (SPhP) mediated heat transfer occurs. In this regime, the net spectral heat rate exhibits four resonant modes due to LSPhs along the minor axis of the probe while the net tota...

  2. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    Bin Luo; Shuang-Nan Zhang

    2004-01-01

    In normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma.We calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions.Our results show that the total radiation power is always lower if the motion of ions is considered.We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow(ADAF)model:we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.

  3. The role of radiation transport in the thermal response of semitransparent materials to localized laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Colvin, Jeffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shestakov, Aleksei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stolken, James [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vignes, Ryan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-09

    Lasers are widely used to modify the internal structure of semitransparent materials for a wide variety of applications, including waveguide fabrication and laser glass damage healing. The gray diffusion approximation used in past models to describe radiation cooling is not adequate for these materials, particularly near the heated surface layer. In this paper we describe a computational model based upon solving the radiation transport equation in 1D by the Pn method with ~500 photon energy bands, and by multi-group radiationdiffusion in 2D with fourteen photon energy bands. The model accounts for the temperature-dependent absorption of infrared laser light and subsequent redistribution of the deposited heat by both radiation and conductive transport. We present representative results for fused silica irradiated with 2–12 W of 4.6 or 10.6 µm laser light for 5–10 s pulse durations in a 1 mm spot, which is small compared to the diameter and thickness of the silica slab. Furthermore, we show that, unlike the case for bulk heating, in localized infrared laser heatingradiation transport plays only a very small role in the thermal response of silica.

  4. Radiative thermal rectification between SiC and SiO2.

    Science.gov (United States)

    Joulain, Karl; Ezzahri, Younès; Drevillon, Jérémie; Rousseau, Benoît; De Sousa Meneses, Domingos

    2015-11-30

    By means of fluctuational electrodynamics, we calculate radiative heat flux between two planar materials respectively made of SiC and SiO2. More specifically, we focus on a first (direct) situation where one of the two materials (for example SiC) is at ambient temperature whereas the second material is at a higher one, then we study a second (reverse) situation where the material temperatures are inverted. When the two fluxes corresponding to the two situations are different, the materials are said to exhibit thermal rectification, a property with potential applications in thermal regulation. Rectification variations with temperature and separation distance are reported here. Calculations are performed using material optical data experimentally determined by Fourier transform emission spectrometry of heated materials between ambient temperature (around 300 K) and 1480 K. It is shown that rectification is much more important in the near-field domain, i.e. at separation distances smaller than the thermal wavelength. In addition, we see that the larger is the temperature difference, the larger is rectification. Large rectification is finally interpreted due to a weakening of the SiC surface polariton when temperature increases, a weakening which affects much less SiO2 resonances.

  5. Surface modification of fluorocarbon polymers by synchrotron radiation

    CERN Document Server

    Kanda, K; Matsui, S; Ideta, T; Ishigaki, H

    2003-01-01

    The surface modification of a poly (tetrafluoroethylene) sheet was carried out by synchrotron radiation in the soft X-ray region. The poly (tetrafluoroethylene) substrate was exposed to synchrotron radiation while varying the substrate temperature from room temperature to 200degC. The contact angle of the modified surfaces with a water drop decreased from 96deg to 72deg by the irradiation at room temperature, while the contact angle increased to 143deg by the irradiation at the substrate temperature of 200degC. Scanning electron microscopy suggested that this repellence was ascribable to the microstructure of the poly (tetrafluoroethylene) surface. We succeeded in controlling the wettability of the poly (tetrafluoroethylene) surface from hydrophobic to hydrophilic by irradiation of the soft X-ray light. (author)

  6. Modeling the impact of solid surfaces in thermal degradation processes

    NARCIS (Netherlands)

    Tuma, Christian; Laino, Teodoro; Martin, Elyette; Stolz, Steffen; Curioni, Alessandro

    2013-01-01

    First-principles simulations are carried out to generate reaction profiles for the initial steps of the thermal decomposition of glycerol, propylene glycol, and triacetin over the surfaces of pseudo-amorphous carbon and silica, crystalline zirconia [001], and crystalline alumina (0001).

  7. Sea surface temperature mapping using a thermal infrared scanner

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Pandya, R.M.; Mathur, K.M.; Charyulu, R.J.K.; Rao, L.V.G.

    1 metre water column below the sea surface. A thermal infrared scanner developed by the Space Applications Centre (ISRO), Ahmedabad was operated on board R.V. Gaveshani in April/May 1984 for mapping SST over the eastern Arabian Sea. SST values...

  8. Heat gain from thermal radiation through protective clothing with different insulation, reflectivity and vapour permeability

    NARCIS (Netherlands)

    Bröde, P.; Kuklane, K.; Candas, V.; Hartog, E.A. den; Griefahn, B.; Holmér, I.; Meinander, H.; Nocker, W.; Richards, M.; Havenith, G.

    2010-01-01

    The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were

  9. Radiation effect on thermal explosion in a gas containing evaporating fuel droplets

    Energy Technology Data Exchange (ETDEWEB)

    Goldfarb, I.; Gol' dshtein, V.; Katz, D. [Department of Mathematics, Faculty of Natural Sciences, Ben Gurion University of the Negev, Grossman Building, P.O.B. 653, Beer Sheva 84105 (Israel); Sazhin, S. [School of Engineering, Faculty of Science and Engineering, University of Brighton, Cockcroft Building, Brighton BN2 4GJ (United Kingdom)

    2007-02-05

    The dynamics of thermal explosion in a fuel droplets/hot air mixture is investigated using the geometrical version of the method of integral manifolds. The results are applied to the modelling of the ignition process in diesel engines. Effects of the thermal radiation, semi-transparency of droplets and oxidizer are taken into account. In contrast to the previous studies, the difference between gas temperature (responsible for convective heating of droplets) and external temperature (responsible for radiative heating of droplets) is taken into account. The dynamics of the explosion is presented in terms of the dynamics of a multi-scale, singularly perturbed system. The relevant parametric regions of this system are analyzed. Explicit analytical formulae for the ignition delay in the presence of thermal radiation are derived. It is shown that the effect of thermal radiation can lead to considerable reduction (up to about 30%) of the total ignition delay time. (author)

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

    Science.gov (United States)

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

    2016-12-01

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

  11. Surface Emissivity Maps for Use in Satellite Retrievals of Longwave Radiation

    Science.gov (United States)

    Wilber, Anne C.; Kratz, David P.; Gupta, Shashi K.

    1999-01-01

    Accurate accounting of surface emissivity is essential for the retrievals of surface temperature from remote sensing measurements, and for the computations of longwave (LW) radiation budget of the Earth?s surface. Past studies of the above topics assumed that emissivity for all surface types, and across the entire LW spectrum is equal to unity. There is strong evidence, however, that emissivity of many surface materials is significantly lower than unity, and varies considerably across the LW spectrum. We have developed global maps of surface emissivity for the broadband LW region, the thermal infrared window region (8-12 micron), and 12 narrow LW spectral bands. The 17 surface types defined by the International Geosphere Biosphere Programme (IGBP) were adopted as such, and an additional (18th) surface type was introduced to represent tundra-like surfaces. Laboratory measurements of spectral reflectances of 10 different surface materials were converted to corresponding emissivities. The 10 surface materials were then associated with 18 surface types. Emissivities for the 18 surface types were first computed for each of the 12 narrow spectral bands. Emissivities for the broadband and the window region were then constituted from the spectral band values by weighting them with Planck function energy distribution.

  12. A fast, exact code for scattered thermal radiation compared with a two-stream approximation. [radiative transfer model

    Science.gov (United States)

    Cogley, A. C.; Pandey, D. K.; Bergstrom, R. W.

    1980-01-01

    A two-stream accuracy study for internally (thermal) driven problems is presented by comparison with a recently developed 'exact' adding/doubling method. The resulting errors in external (or boundary) radiative intensity and flux are usually larger than those for the externally driven problems and vary substantially with the radiative parameters. Error predictions for a specific problem are difficult. An unexpected result is that the exact method is computationally as fast as the two-stream approximation for nonisothermal media.

  13. Weathering of coil-coatings: UV radiation and thermal effects

    Directory of Open Access Journals (Sweden)

    Castela, A. S.

    2003-12-01

    Full Text Available The effect of heat and of QUV ageing on coil coatings was tested by electrochemical impedance, and the results compared with surface analysis of the polymers by FTIR and XPS. It was shown that UV radiation is more relevant than heat to chemical degradation. A different correlation between water permeation and chemical degradation was observed depending on the coating thickness: for the thinner coatings, the higher UV degradation has corresponded to increased water absorption, whereas in the thicker coating, the bulk effect of heat was more relevant to water permeation.

    El efecto del calor y del envejecimiento, QUV, sobre recubrimiemtos de bobinas se probó mediante la impedancia electroquímica, y los resultados se compararon con análisis superficiales de los polímeros usando FTIR y XPS. Se encontró que la radiación UV es más importante que el calor en la degradación química. Una correlación diferente, entre agua infiltrada y degradación química, se observó, dependiendo del espesor del recubrimiento: para los recubrimientos más delgados, mayor degradación UV correspondió a un incremento de absorción de agua; en cambio, para los recubrimientos más gruesos, el efecto del calor fue más importante para la infiltración del agua.

  14. Biocompatibility of Er:YSGG laser radiated root surfaces

    Science.gov (United States)

    Benthin, Hartmut; Ertl, Thomas P.; Schmidt, Dirk; Purucker, Peter; Bernimoulin, J.-P.; Mueller, Gerhard J.

    1996-01-01

    Pulsed Er:YAG and Er:YSGG lasers are well known to be effective instruments for the ablation of dental hard tissues. Developments in the last years made it possible to transmit the laser radiation at these wavelengths with flexible fibers. Therefore the application in the periodontal pocket may be possible. The aim of this study was to evaluate the in-vitro conditions to generate a bioacceptable root surface. Twenty extracted human teeth, stored in an antibiotic solution, were conventionally scaled, root planed and axially separated into two halves. Two main groups were determined. With the first group laser radiation was carried out without and in the second group with spray cooling. The laser beam was scanned about root surface areas. Laser parameters were varied in a selected range. The biocompatibility was measured with the attachment of human gingival fibroblasts and directly compared to conventionally treated areas of the root surfaces. The fibroblasts were qualified and counted in SEM investigations. On conventionally treated areas gingival fibroblasts show the typical uniform cover. In dependance on the root roughness after laser treatment the fibroblasts loose the typical parallel alignment to the root surface. With spray cooling a better in-vitro attachment could be obtained. Without spray cooling the higher increase in temperature conducted to less bioacceptance by the human gingival fibroblasts to the root surface. These results show the possibility of producing bioacceptable root surfaces with pulsed laser radiation in the range of very high water absorption near 3 micrometer.

  15. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    Science.gov (United States)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  16. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    Science.gov (United States)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 10(exp 13) to 10(exp 15) n per square centimeters. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 10(exp 15) to 10(exp 16) n per square centimeters with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  17. HIGH VELOCITY THERMAL GUN FOR SURFACE PREPARATION AND TREATMENT

    Directory of Open Access Journals (Sweden)

    I.A. Gorlach

    2012-01-01

    Full Text Available Many surface preparation and treatment processes utilise compressed air to propel particles against surfaces in order to clean and treat them. The effectiveness of the processes depends on the velocity of the particles, which in turn depends on the pressure of the compressed air. This paper describes a thermal gun built on the principles of High Velocity Air Fuel (HVAF and High Velocity Oxy Fuel (HVOF processes. The designed apparatus can be used for abrasive blasting, coating of surfaces, cutting of rocks, removing rubber from mining equipment, cleaning of contaminations etc.

  18. Two-Phase Thermal Switching System for a Small, Extended Duration Lunar Surface Science Platform

    Science.gov (United States)

    Bugby, David C.; Farmer, Jeffery T.; OConnor, Brian F.; Wirzburger, Melissa J.; Abel, Elisabeth D.; Stouffer, Chuck J.

    2010-01-01

    This paper describes a novel thermal control system for the Warm Electronics Box (WEB) on board a small lunar surface lander intended to support science activities anywhere on the lunar surface for an extended duration of up to 6 years. Virtually all lander electronics, which collectively dissipate about 60 W in the reference mission, are contained within the WEB. These devices must be maintained below 323 K (with a goal of 303 K) during the nearly 15-earth-day lunar day, when surface temperatures can reach 390K, and above 263 K during the nearly 15-earth-day lunar night, when surface temperatures can reach 100K. Because of the large temperature swing from lunar day-to-night, a novel thermal switching system was required that would be able to provide high conductance from WEB to radiator(s) during the hot lunar day and low (or negligible) conductance during the cold lunar night. The concept that was developed consists of ammonia variable conductance heat pipes (VCHPs) to collect heat from WEB components and a polymer wick propylene loop heat pipe (LHP) to transport the collected heat to the radiator(s). The VCHPs autonomously maximize transport when the WEB is warm and autonomously shut down when the WEB gets cold. The LHP autonomously shuts down when the VCHPs shut down. When the environment transitions from lunar night to day, the VCHPs and LHP autonomously turn back on. Out of 26 analyzed systems, this novel arrangement was able to best achieve the combined goals of zero control power, autonomous operation, long life, low complexity, low T, and landed tilt tolerance.

  19. Radiation-Induced Nano-Explosions at the Solid Surface:Near Surface Radiation Damage in CR-39 Polymer

    Institute of Scientific and Technical Information of China (English)

    Mukhtar Ahmed Rana

    2011-01-01

    @@ New measurements of fission fragment and alpha particle induced surface damage in the most sensitive and commonly used nuclear track detector CR-39 are presented here.Precisely designed and optimized exposure and chemical etching experiments are employed to unfold the structure of radiation induced surface damage (RISD).Delay in the startup of the chemical etching of latent tracks or surface radiation damage is measured and is found to contain important information about the structure of the surface damage.Simple atomic scale pictures of RISD and its chemical etching are developed in an empirical manner.Theoretical model and experimental findings coherently compose a realistic picture of early or ferntosecond evolution of RISD.

  20. Thermostimulated THz Radiation Emission of GaAs at Surface Plasmon-Phonon Polariton Frequencies

    Directory of Open Access Journals (Sweden)

    Edmundas ŠIRMULIS

    2014-06-01

    Full Text Available The THz radiation reflection, absorption and emission spectra of conductive n-GaAs/air surface are considered. The influence of thermostimulated surface plasmon-phonon (SPP polariton oscillations on THz radiation reflection, absorption and emission of high conductivity GaAs polished plates with electron density n = 7∙1017 cm–3 and 4∙1018 cm–3 and thickness of 350 mm is studied experimentally. The frequencies of thermostimulated transverse and longitudinal optical phonons and SPP oscillations, which characterize a heated lattice state, were determined. It is found that the heated highly doped interface layer (GaAs/air emits the THz radiation at selected frequencies of SPP oscillations in the (7 – 8 THz and (10 – 15 THz ranges. It is shown that thermal heating of the GaAs/air interface enhances the absorption of the incident THz radiation. The huge decrease of the incident radiation reflectivity at the SPP frequencies with an increase of GaAs temperature is observed experimentally. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6318

  1. Emergent geometry, thermal CFT and surface/state correspondence

    CERN Document Server

    Gan, Wen-Cong; Wu, Meng-He

    2016-01-01

    We study a conjectured correspondence between any codimension two convex surface and a quantum state (SS-duality for short). By generalizing thermofield double formalism to continuum version of the multi-scale entanglement renormalization ansatz (cMERA) and using the SS-duality, we propose a general framework to emerge the thermal geometry from CFT at finite temperature. As an example, the case of $2d$ CFT is considered carefully. We calculate its information metric and show that it is the BTZ black hole or the thermal AdS as expectation.

  2. Surface ultraviolet radiation over east Siberia: seasonal variations

    Directory of Open Access Journals (Sweden)

    A. V. Mikhalev

    Full Text Available The results of spectral measurements of the daily near-noon surface direct solar ultraviolet radiation in the wavelength range of 295–345 nm obtained in Irkutsk (East Siberia for the time interval of 1998–2000 are presented. For the period under consideration, the seasonal UV radiation variations are analysed that are associated with the total ozone dynamics, the transition of cyclonic and anticyclonic (Siberian anticyclone periods, the presence of snow cover, and other factors. The analysis reveals an asymmetric behaviour of the seasonal course in ground-level UV radiation around the time of the summer solstice, with seasonal variation dependence on the wavelength. We have determined the irregular variations of surface UV radiation that is typical for the region, with their properties dependent on the season and on the spectral range analysed. The similarity of the above noted features from year to year was revealed.

    Key words. Atmospheric composition and structure (Transmission and scattering of radiation; instruments and techniques – Meteorology and atmospheric dynamics (middle atmosphere dynamics

  3. Thermal radiation of laser heated niobium clusters Nb(+)(N), 8 ⩽ N ⩽ 22.

    Science.gov (United States)

    Hansen, Klavs; Li, Yejun; Kaydashev, Vladimir; Janssens, Ewald

    2014-07-14

    The thermal radiation from small, laser heated, positively charged niobium clusters has been measured. The emitted power was determined by the quenching effect on the metastable decay, employing two different experimental protocols. The radiative power decreases slightly with cluster size and shows no strong size-to-size variations. The magnitude is 40-50 keV/s at the timescale of several microseconds, which is the measured crossover time from evaporative to radiative cooling.

  4. Thermal Radiation Laws of a q-deformed Boson System in m Dimensions

    Science.gov (United States)

    Zeng, QiJun; Ge, Jing; Luo, Hao; Luo, YongSong

    2017-09-01

    Within the theoretical framework of multidimensional space and q bosons, we generalize our hypothesis of regarding the CMBR as the radiation of q bosons, and investigate the thermal radiation laws of a q boson system in m dimensions. Utilizing the new radiation laws, we make a numerical calculation and the results show that these new laws have some special features. We consider that this work may provide more insight into the theory of q bosons and the study on the CMBR.

  5. The influence of thermal radiation on MHD station-point flow past a stretching sheet with heat generation

    Institute of Scientific and Technical Information of China (English)

    Jing Zhu; Lian-Cun Zheng; Xin-Xin Zhang

    2011-01-01

    This letter is concerned with the plane and axisymmetric stagnation-point flows and heat transfer of an electrically-conducting fluid past a stretching sheet in the presence of the thermal radiation and heat generation or absorption. The analytical solutions for the velocity distribution and dimensionless temperature profiles are obtained for the various values of the ratio of free stream velocity and stretching velocity,heat source parameter,Prandtl number,thermal radiation parameter,the suction and injection velocity parameter and magnetic parameter and dimensionality index in the series form with the help of homotopy analysis method(HAM). Convergence of the series is explicitly discussed. In addition,shear stress and heat flux at the surface are calculated.

  6. A comparison of different entransy flow definitions and entropy generation in thermal radiation optimization

    Institute of Scientific and Technical Information of China (English)

    Zhou Bing; Cheng Xue-Tao; Liang Xin-Gang

    2013-01-01

    In thermal radiation,taking heat flow as an extensive quantity and defining the potential as temperature T or the blackbody emissive power U will lead to two different definitions of radiation entransy flow and the corresponding principles for thermal radiation optimization.The two definitions of radiation entransy flow and the corresponding optimization principles are compared in this paper.When the total heat flow is given,the optimization objectives of the extremum entransy dissipation principles (EEDPs) developed based on potentials T and U correspond to the minimum equivalent temperature difference and the minimum equivalent blackbody emissive power difference respectively.The physical meaning of the definition based on potential U is clearer than that based on potential T,but the latter one can be used for the coupled heat transfer optimization problem while the former one cannot.The extremum entropy generation principle (EEGP) for thermal radiation is also derived,which includes the minimum entropy generation principle for thermal radiation.When the radiation heat flow is prescribed,the EEGP reveals that the minimum entropy generation leads to the minimum equivalent thermodynamic potential difference,which is not the expected objective in heat transfer.Therefore,the minimum entropy generation is not always appropriate for thermal radiation optimization.Finally,three thermal radiation optimization examples are discussed,and the results show that the difference in optimization objective between the EEDPs and the EEGP leads to the difference between the optimization results.The EEDP based on potential T is more useful in practical application since its optimization objective is usually consistent with the expected one.

  7. Relevance of decadal variations in surface radiative fluxes for climate change

    Science.gov (United States)

    Wild, Martin

    2013-05-01

    Recent evidence suggests that radiative fluxes incident at Earth's surface are not stable over time but undergo significant changes on decadal timescales. This is not only found in the thermal spectral range, where an increase in the downwelling flux is expected due to the increasing greenhouse effect, but also in the solar spectral range. Observations suggest that surface solar radiation, after a period of decline from the 1950s to the 1980s ("global dimming"), reversed into a "brightening" since the mid-1980s at widespread locations, often in line with changes in anthropogenic air pollution. These decadal variations observed in both solar and thermal surface radiative fluxes have the potential to affect various aspects of climate change. Discussed here are specifically the evidence for potential effects on global warming, as seen in asymmetries in hemispheric warming rates as well as in differences in the decadal warming rates over land and oceans. These variations in observed warming rates fit well to our conceptual understanding of how aerosol and greenhouse gas-induced changes in the surface radiative fluxes should affect global warming. Specifically, on the Northern Hemisphere, the suppression of warming from the 1950s to the 1980s fits to the concurrent dimming and increasing air pollution, while the accelerated warming from the 1980s to 2000 matches with the brightening and associated reduction in pollution levels. The suppression of warming from the 1950s to the 1980s is even somewhat stronger over oceans than over land, in line with the conceptual idea that aerosol-induced dimming and brightening tendencies may be enhanced through cloud aerosol interactions particularly over the pristine ocean areas. On the Southern Hemisphere, the absence of significant pollution levels as well as trend reversals therein, fit to the observed stable warming rates over the entire 1950 to 2000 period.

  8. Optimum Location of Thermal Radiation Shield in Superconducting Rotating Machines

    Science.gov (United States)

    Saikiran, P. A.; Rao, V. V.

    2017-02-01

    Superconducting rotating machines have rotor maintained at low temperatures, below the critical temperature of the superconductor. This establishes large temperature difference between the cold rotor and surroundings, resulting in large heat leak into rotor through conduction, convection and radiation. Minimizing this heat leak is essential to reduce the power expense of cryogenic cooling system. A radiation shield is anchored at a suitable location on torque tube to minimize the radiation heat leak into the cold rotor. This paper presents a methodology to determine the optimum location of this anchor-point of radiation shield for a given geometry, which minimizes the total heat leak into cold rotor. The location of radiation shield is found to be depending on emissivity of cold rotor.

  9. Radiative contribution to thermal conductance in animal furs and other woolly insulators.

    Science.gov (United States)

    Simonis, Priscilla; Rattal, Mourad; Oualim, El Mostafa; Mouhse, Azeddine; Vigneron, Jean-Pol

    2014-01-27

    This paper deals with radiation's contribution to thermal insulation. The mechanism by which a stack of absorbers limits radiative heat transfer is examined in detail both for black-body shields and grey-body shields. It shows that radiation energy transfer rates should be much faster than conduction rates. It demonstrates that, for opaque screens, increased reflectivity will dramatically reduce the rate of heat transfer, improving thermal insulation. This simple model is thought to contribute to the understanding of how animal furs, human clothes, rockwool insulators, thermo-protective containers, and many other passive energy-saving devices operate.

  10. Magnetic nanofluid natural convection in the presence of thermal radiation considering variable viscosity

    Science.gov (United States)

    Sheikholeslami, Mohsen; Rokni, Houman B.

    2017-05-01

    Magnetohydrodynamic nanofluid flow and convective heat transfer are studied considering thermal radiation. Effects of magnetic field and shape of nanoparticles on viscosity and thermal conductivity of the nanofluid are taken into account. The solutions of final equations are obtained by the control volume-based finite-element method (CVFEM). Roles of shape of nanoparticles, radiation parameter, ferrofluid volume fraction, Hartmann and Rayleigh numbers are presented graphically. Results demonstrate that selecting the Platelet shape for Fe3O4 nanoparticles leads to maximum Nusselt number. Rate of heat transfer increases with increasing Rayleigh number and radiation parameter but it decreases with increasing Hartmann number.

  11. Effect of Ni content on thermal and radiation resistance of VVER RPV steel

    Science.gov (United States)

    Shtrombakh, Ya. I.; Gurovich, B. A.; Kuleshova, E. A.; Frolov, A. S.; Fedotova, S. V.; Zhurko, D. A.; Krikun, E. V.

    2015-06-01

    In this paper thermal stability and radiation resistance of VVER-type RPV steels for pressure vessels of advanced reactors with different nickel content were studied. A complex of microstructural studies and mechanical tests of the steels in different states (after long thermal exposures, provoking embrittling heat treatment and accelerated neutron irradiation) was carried out. It is shown that nickel content (other things being equal) determines the extent of materials degradation under influence of operational factors: steels with a lower nickel concentration demonstrate a higher thermal stability and radiation resistance.

  12. Experimental Characterization of a Composite Morphing Radiator Prototype in a Relevant Thermal Environment

    Science.gov (United States)

    Bertagne, Christopher L.; Chong, Jorge B.; Whitcomb, John D.; Hartl, Darren J.; Erickson, Lisa R.

    2017-01-01

    For future long duration space missions, crewed vehicles will require advanced thermal control systems to maintain a desired internal environment temperature in spite of a large range of internal and external heat loads. Current radiators are only able to achieve turndown ratios (i.e. the ratio between the radiator's maximum and minimum heat rejection rates) of approximately 3:1. Upcoming missions will require radiators capable of 12:1 turndown ratios. A radiator with the ability to alter shape could significantly increase turndown capacity. Shape memory alloys (SMAs) offer promising qualities for this endeavor, namely their temperature-dependent phase change and capacity for work. In 2015, the first ever morphing radiator prototype was constructed in which SMA actuators passively altered the radiator shape in response to a thermal load. This work describes a follow-on endeavor to demonstrate a similar concept using highly thermally conductive composite materials. Numerous versions of this new concept were tested in a thermal vacuum environment and successfully demonstrated morphing behavior and variable heat rejection, achieving a turndown ratio of 4.84:1. A summary of these thermal experiments and their results are provided herein.

  13. Clear-sky radiative closure for the Cabauw Baseline Surface Radiation Network site, the Netherlands

    NARCIS (Netherlands)

    Wang, P.; Knap, W.H.; Kuipers Munneke, P.; Stammes, P.

    2009-01-01

    In this paper a clear-sky shortwave closure analysis is presented for the Baseline Surface Radiation Network (BSRN) site of Cabauw, Netherlands (51.97°N, 4.93°E). The analysis is based on an exceptional period of fine weather during the first half of May 2008, resulting in a selection of 72 comparis

  14. Clear-sky radiative closure for the Cabauw Baseline Surface Radiation Network site, the Netherlands

    NARCIS (Netherlands)

    Wang, P.; Knap, W.H.; Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; Stammes, P.

    2009-01-01

    In this paper a clear-sky shortwave closure analysis is presented for the Baseline Surface Radiation Network (BSRN) site of Cabauw, Netherlands (51.97°N, 4.93°E). The analysis is based on an exceptional period of fine weather during the first half of May 2008, resulting in a selection of 72

  15. Tailoring radiation damage in ZnO by surface modification

    Science.gov (United States)

    Myers, M. T.; Charnvanichborikarn, S.; Myers, M. A.; Lee, J. H.; Wang, H.; Biener, M. M.; Shao, L.; Kucheyev, S. O.

    2013-07-01

    Heavy-ion irradiation of (0 0 0 1) ZnO crystals results in unusual damage buildup, including an additional (intermediate) peak in damage-depth profiles measured by ion channeling, the formation of near-surface nanocavities, and stoichiometric imbalance. All these effects are thought to be associated with the influence of the sample surface on dynamic annealing processes. Here, by using ion channeling and transmission electron microscopy, we find that placing an ~7 nm thick AlO(OH) layer on the (0 0 0 1) ZnO surface results in (i) suppression of cavity formation, (ii) a reduced intermediate defect peak intensity, and (iii) a decreased level of disorder extending up to ~100 nm from the ZnO surface for room-temperature bombardment with 500 keV Xe ions. Our results demonstrate the potential to control radiation damage in ZnO by surface manipulation.

  16. Surface treatment of CFRP composites using femtosecond laser radiation

    Science.gov (United States)

    Oliveira, V.; Sharma, S. P.; de Moura, M. F. S. F.; Moreira, R. D. F.; Vilar, R.

    2017-07-01

    In the present work, we investigate the surface treatment of carbon fiber-reinforced polymer (CFRP) composites by laser ablation with femtosecond laser radiation. For this purpose, unidirectional carbon fiber-reinforced epoxy matrix composites were treated with femtosecond laser pulses of 1024 nm wavelength and 550 fs duration. Laser tracks were inscribed on the material surface using pulse energies and scanning speeds in the range 0.1-0.5 mJ and 0.1-5 mm/s, respectively. The morphology of the laser treated surfaces was investigated by field emission scanning electron microscopy. We show that, by using the appropriate processing parameters, a selective removal of the epoxy resin can be achieved, leaving the carbon fibers exposed. In addition, sub-micron laser induced periodic surface structures (LIPSS) are created on the carbon fibers surface, which may be potentially beneficial for the improvement of the fiber to matrix adhesion in adhesive bonds between CFRP parts.

  17. Surface dielectric relaxation: probing technique and its application to thermal activation dynamics of polymer surface.

    Science.gov (United States)

    Ishii, Masashi

    2010-09-01

    For dynamic analyses of a polymer surface, a dielectric relaxation measurement technique with parallel electrodes placed away from the surface was developed. In this technique, a liquid heating medium was filled in the space between the polymer surface and the electrodes. The construction that maintains the surface can clarify the physical interactions between the liquid and the bare surface and controlling the temperature of the liquid reveals the thermal activation property of the surface. The dielectric relaxation spectrum of the surface convoluted into the bulk and liquid spectra can be obtained by a reactance analysis and the surface spectrum is expressed with an equivalent resistance-capacitance parallel circuit. On the basis of the electromechanical analogy, the electric elements can be converted into mechanical elements that indicate the viscoelasticity of the polymer surface. Using these measurement and analysis techniques, the electric and mechanical properties of the surface of a gelatinized chloroprene rubber sample were analyzed.

  18. Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

    2015-12-01

    Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

  19. Determination of thermal/dynamic characteristics of lava flow from surface thermal measurements

    Science.gov (United States)

    Ismail-Zadeh, Alik; Melnik, Oleg; Korotkii, Alexander; Tsepelev, Igor; Kovtunov, Dmitry

    2016-04-01

    Rapid development of ground based thermal cameras, drones and satellite data allows getting repeated thermal images of the surface of the lava flow. Available instrumentation allows getting a large amount of data during a single lava flow eruption. These data require development of appropriate quantitative techniques to link subsurface dynamics with observations. We present a new approach to assimilation of thermal measurements at lava's surface to the bottom of the lava flow to determine lava's thermal and dynamic characteristics. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. Using an adjoint method we develop a numerical approach to the mathematical problem based on the determination of the missing boundary condition and lava flow characteristics. Numerical results show that in the case of smooth input data lava temperature and velocity can be determined with a high accuracy. A noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. The proposed approach to assimilate measured data brings an opportunity to estimate thermal budget of the lava flow.

  20. Experimental study of the surface thermal signature of gravity currents: application to the assessment of lava flow effusion rate

    Science.gov (United States)

    Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

    2011-12-01

    During an effusive volcanic eruption, the crisis management is mainly based on the prediction of lava flows advance and its velocity. As the spreading of lava flows is mainly controlled by its rheology and the eruptive mass flux, the key question is how to evaluate them during the eruption (rather than afterwards.) A relationship between the heat flux lost by the lava at its surface and the eruption rate is likely to exist, based on the first-order argument that higher eruption rates should correspond to larger power radiated by a lava flow. The semi-empirical formula developed by Harris and co-workers (e.g. Harris et al., Bull. Volc. 2007) is currently used to estimate lava flow rate from satellite surveys yielding the surface temperatures and area of the lava flow field. However, this approach is derived from a static thermal budget of the lava flow and does not explicitly model the time-evolution of the surface thermal signal. Here we propose laboratory experiments and theoretical studies of the cooling of a viscous axisymmetric gravity current fed at constant flux rate. We first consider the isoviscous case, for which the spreading is well-know. The experiments using silicon oil and the theoretical model both reveal the establishment of a steady surface thermal structure after a transient time. The steady state is a balance between surface cooling and heat advection in the flow. The radiated heat flux in the steady regime, a few days for a basaltic lava flow, depends mainly on the effusion rate rather than on the viscosity. In this regime, one thermal survey of the radiated power could provide a consistent estimate of the flow rate if the external cooling conditions (wind) are reasonably well constrained. We continue to investigate the relationship between the thermal radiated heat flux and the effusion rate by using in the experiments fluids with temperature-dependent viscosity (glucose syrup) or undergoing solidification while cooling (PEG wax). We observe a

  1. THERMAL FRACTURE OF FUNCTIONALLY GRADED PLATE WITH PARALLEL SURFACE CRACKS

    Institute of Scientific and Technical Information of China (English)

    Yuezhong Feng; Zhihe Jin

    2009-01-01

    This work examines the fracture behavior of a functionally graded material (FGM) plate containing parallel surface cracks with alternating lengths subjected to a thermal shock. The thermal stress intensity factors (TSIFs) at the tips of long and short cracks are calculated using a singular integral equation technique. The critical thermal shock △T_c that causes crack initiation is calculated using a stress intensity factor criterion. Numerical examples of TSIFs and △T_c for an Al_2O_3/Si_3N_4 FGM plate are presented to illustrate the effects of thermal property gradation, crack spacing and crack length ratio on the TSIFs and △T_c. It is found that for a given crack length ratio, the TSIFs at the tips of both long and short cracks can be reduced significantly and △T_c can be enhanced by introducing appropriate material gradation. The TSIFs also decrease dramatically with a decrease in crack spacing. The TSIF at the tips of short cracks may be higher than that for the long cracks under certain crack geometry conditions. Hence, the short cracks instead of long cracks may first start to grow under the thermal shock loading.

  2. Improving Energy Efficiency In Thermal Oil Recovery Surface Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Murthy Nadella, Narayana

    2010-09-15

    Thermal oil recovery methods such as Cyclic Steam Stimulation (CSS), Steam Assisted Gravity Drainage (SAGD) and In-situ Combustion are being used for recovering heavy oil and bitumen. These processes expend energy to recover oil. The process design of the surface facilities requires optimization to improve the efficiency of oil recovery by minimizing the energy consumption per barrel of oil produced. Optimization involves minimizing external energy use by heat integration. This paper discusses the unit processes and design methodology considering thermodynamic energy requirements and heat integration methods to improve energy efficiency in the surface facilities. A design case study is presented.

  3. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats

    Directory of Open Access Journals (Sweden)

    Haitham S. Mohammed

    2013-03-01

    Full Text Available In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day. EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS and rapid eye movement sleep (REM sleep revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

  4. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats.

    Science.gov (United States)

    Mohammed, Haitham S; Fahmy, Heba M; Radwan, Nasr M; Elsayed, Anwar A

    2013-03-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

  5. INTEGRAL RADIATORS FOR NEXT GENERATION THERMAL CONTROL SYSTEMS Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of spacecraft thermal control systems is to maintain internal and external temperature within acceptable boundaries while minimizing impact on vehicle...

  6. Martian sub-surface ionising radiation: biosignatures and geology

    Directory of Open Access Journals (Sweden)

    J. M. Ward

    2007-07-01

    Full Text Available The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionising radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Here, we present modelling results of the absorbed radiation dose as a function of depth through the Martian subsurface, suitable for calculation of biomarker persistence. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments.

    We present calculations of the dose-depth profile in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost, solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude, and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and discuss particle deflection by the crustal magnetic fields.

  7. Martian sub-surface ionising radiation: biosignatures and geology

    Directory of Open Access Journals (Sweden)

    L. R. Dartnell

    2007-02-01

    Full Text Available The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionizing radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Previous research has attempted to address the question of biomarker persistence by inappropriately using dose profiles weighted specifically for cellular survival. Here, we present modelling results of the unmodified physically absorbed radiation dose as a function of depth through the Martian subsurface. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments.

    We present calculations of the dose-depth profile from galactic cosmic rays in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost, solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude, and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and briefly treat particle deflection by the crustal magnetic fields.

  8. Solar radiation calculation methodology for building exterior surfaces

    Energy Technology Data Exchange (ETDEWEB)

    De la Flor, Francisco Jose Sanchez; Ortiz Cebolla, Rafael; Luis Molina Felix, Jose; Alvarez Dominguez, Servando [E S. Ingenieros. Grupo de Termotecnia, Avda. de los descubrimientos, s/n 41092 Sevilla (Spain)

    2005-11-01

    The present article shows a new methodology of calculation of the direct, diffuse and reflected incident solar radiation, in all type of surfaces, either in open urban environments or inside buildings. This methodology is applicable in problems related to solar access (space heating in buildings, shadowing of open spaces), solar gains (space cooling in buildings), and daylighting. Solar radiation is the most important contribution to the surface and volumetric energy balance during the daytime. Particularly, solar radiation is the main contributor to heat gains in buildings, especially in residential buildings, where internal gains are very low. Utilization of daylight in buildings may result in significant savings in electricity consumption for lighting while creating a higher quality indoor environment. Additional energy savings may also be realized during cooling season, when reduction of internal heat gains due to electric lighting results in a corresponding reduction of cooling energy consumption. The analysis of the existing calculation methods and proposed in the scientific bibliography for the calculation of the solar radiation in problems of solar access in winter, solar gains in summer, and daylighting, takes us to the necessity of outlining a new and complete methodology. This new methodology is applicable to all these problems with a great accuracy and calculation speed. (author)

  9. Salts and radiation products on the surface of Europa

    CERN Document Server

    Brown, M E

    2013-01-01

    The surface of Europa could contain the compositional imprint of a underlying interior ocean, but competing hypotheses differ over whether spectral observations from the Galileo spacecraft show the signature of ocean evaporates or simply surface radiation products unrelated to the interior. Using adaptive optics at the W.M. Keck Observatory, we have obtained spatially resolved spectra of most of the disk of Europa at a spectral resolution ~40 times higher than seen by the Galileo spacecraft. These spectra show a previously undetected distinct signature of magnesium sulfate salts on Europa, but the magnesium sulfate is confined to the trailing hemisphere and spatially correlated with the presence of radiation products like sulfuric acid and SO2. On the leading, less irradiated, hemisphere, our observations rule out the presence of many of the proposed sulfate salts, but do show the presence of distorted water ice bands. Based on the association of the potential MgSO4, detection on the trailing side with other ...

  10. Degradation of Teflon(tm) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    Science.gov (United States)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1998-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(R) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(R) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(R) FEP.

  11. Degradation of Teflon(trademark) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    Science.gov (United States)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1999-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(trademark) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(trademark) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(trademark) FEP.

  12. Shuttle active thermal control system development testing. Volume 7: Improved radiator coating adhesive tests

    Science.gov (United States)

    Reed, M. W.

    1973-01-01

    Silver/Teflon thermal control coatings have been tested on a modular radiator system projected for use on the space shuttle. Seven candidate adhesives have been evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint on or spray on adhesives. The coatings attached with four of the adhesives, two silicones and two urethanes, had no changes develop during the thermal vacuum test. The two silicone adhesives, both of which were applied to the silver/Teflon as transfer laminates to form a tape, offered the most promise based on application process and thermal performance. Each of the successful silicone adhesives required a heat and pressure cure to adhere during the cryogenic temperature excursion of the thermal-vacuum test.

  13. Glass transition near the free surface studied by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sikorski, M.

    2008-06-15

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-{mu}m length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  14. Combined non-gray conductive and radiative heat transfer simulation of a single glass window subjected to solar and thermal radiation

    Directory of Open Access Journals (Sweden)

    Khoukhi Maatouk

    2015-01-01

    Full Text Available Combined nongray conductive and radiative heat transfer in single glass window using the Radiation Element Method by Ray Emission Model REM2, has been investigated in one dimensional case. The optical constants of the glass window have been determined by using Fourier Transform Infrared Spectrophotometer (FTIR. The absorption and emission within the glass layer are taken into consideration. The boundary surfaces of the glass are specular. Spectral dependence of radiation properties of the glass is taken into account. Both collimated and diffuse solar and thermal irradiations are applied at boundary surfaces, using the spectral solar model proposed by Bird. The simulation has been performed for one position of the sun at noon true solar time on the 5th of July for three locations in Japan, Sendai, Tokyo, and Sapporo cities. Steady state temperature and heat flux distributions within the glass layer for each position of the sun of the three locations are obtained. The radiative heat flux through the glass mediums is the predominant mode compared with the conductive one. Therefore, the temperature distributions within the glass layer are not linear in shape.

  15. Thermal dynamics-based mechanism for intense laser-induced material surface vaporization

    Indian Academy of Sciences (India)

    N Kumar; S Dash; A K Tyagi; Baldev Raj

    2008-09-01

    Laser material processing involving welding, ablation and cutting involves interaction of intense laser pulses of nanosecond duration with a condensed phase. Such interaction involving high brightness radiative flux causes multitude of non-linear events involving thermal phase transition at soild–liquid–gas interfaces. A theoretical perspective involving thermal dynamics of the vaporization process and consequent non-linear multiple thermal phase transitions under the action of laser plasma is the subject matter of the present work. The computational calculations were carried out where titanium (Ti) was treated as a condensed medium. The solution to the partial differential equations governing the thermal dynamics and the underlying phase transition event in the multiphase system is based on non-stationary Eulerian variables. The Mach number depicts significant fluctuations due to thermal instabilities associated with the laser beam flux and intensity. A conclusive amalgamation has been established which relates material surface temperature profile to laser intensity, laser flux and the pressure in the plasma cloud.

  16. The role of a convective surface in models of the radiative heat transfer in nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, M.M., E-mail: mansurdu@yahoo.com; Al-Mazroui, W.A.; Al-Hatmi, F.S.; Al-Lawatia, M.A.; Eltayeb, I.A.

    2014-08-15

    Highlights: • The role of a convective surface in modelling with nanofluids is investigated over a wedge. • Surface convection significantly controls the rate of heat transfer in nanofluid. • Increased volume fraction of nanoparticles to the base-fluid may not always increase the rate of heat transfer. • Effect of nanoparticles solid volume fraction depends on the types of constitutive materials. • Higher heat transfer in nanofluids is found in a moving wedge rather than in a static wedge. - Abstract: Nanotechnology becomes the core of the 21st century. Nanofluids are important class of fluids which help advancing nanotechnology in various ways. Convection in nanofluids plays a key role in enhancing the rate of heat transfer either for heating or cooling nanodevices. In this paper, we investigate theoretically the role of a convective surface on the heat transfer characteristics of water-based nanofluids over a static or moving wedge in the presence of thermal radiation. Three different types of nanoparticles, namely copper Cu, alumina Al{sub 2}O{sub 3} and titanium dioxide TiO{sub 2} are considered in preparation of nanofluids. The governing nonlinear partial differential equations are made dimensionless with the similarity transformations. Numerical simulations are carried out through the very robust computer algebra software MAPLE 13 to investigate the effects of various pertinent parameters on the flow field. The obtained results presented graphically as well as in tabular form and discussed from physical and engineering points of view. The results show that the rate of heat transfer in a nanofluid in the presence of thermal radiation significantly depends on the surface convection parameter. If the hot fluid side surface convection resistance is lower than the cold fluid side surface convection resistance, then increased volume fraction of the nanoparticles to the base fluid may reduces the heat transfer rate rather than increases from the surface of

  17. Estimation of Solar Radiation Incident on Horizontal and Tilted Surfaces For 7 Colombian Zones

    OpenAIRE

    Corredor, L.M

    2013-01-01

    This paper discusses a procedure that was adopted for the development of a linear regression model for estimating solar radiation on horizontal surfaces for 7 Colombian zones. The correlations, the simulated global solar radiation on tilted surface and the simulated diffuse solar radiation on a horizontal surface for each zone are shown. The values of sunshine-hours and the solar radiation were taken from January 2012 to January 2013. The solar radiation values...

  18. Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface.

    Science.gov (United States)

    Zhang, Aizhong; Maki, Kara L; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Hindman, Holly B; Aquavella, James V; Zavislan, James M

    2015-03-01

    In this study, we explore the usage of ocular surface temperature (OST) decay patterns to distinguished between dry eye patients with aqueous deficient dry eye (ADDE) and meibomian gland dysfunction (MGD). The OST profiles of 20 dry eye subjects were measured by a long-wave infrared thermal camera in a standardized environment (24 °C, and relative humidity (RH) 40%). The subjects were instructed to blink every 5 s after 20 ∼ 25 min acclimation. Exponential decay curves were fit to the average temperature within a region of the central cornea. We find the MGD subjects have both a higher initial temperature (p thermal impulse perturbation (TIP) model. We conclude that long-wave-infrared thermal imaging is a plausible tool in assisting with the classification of dry eye patient.

  19. Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khandekar, Chinmay; Rodriguez, Alejandro W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540 (United States); Lin, Zin [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02139 (United States)

    2015-04-13

    We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.

  20. Surface aerosol radiative forcing derived from collocated ground-based radiometric observations during PRIDE, SAFARI, and ACE-Asia.

    Science.gov (United States)

    Hansell, Richard A; Tsay, Si-Chee; Ji, Qiang; Liou, K N; Ou, Szu-Cheng

    2003-09-20

    An approach is presented to estimate the surface aerosol radiative forcing by use of collocated cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Puerto Rico Dust Experiment 2000, South African Fire Atmosphere Research Initiative (SAFARI) 2000, and Aerosol Characterization Experiment-Asia 2001. We show that aerosol optical depths from the Multiple-Filter Rotating Shadowband Radiometer data match closely with those from the Cimel sunphotometer data for two SAFARI-2000 dates. The observed aerosol radiative forcings were interpreted on the basis of results from the Fu-Liou radiative transfer model, and, in some cases, cross checked with satellite-derived forcing parameters. Values of the aerosol radiative forcing and forcing efficiency, which quantifies the sensitivity of the surface fluxes to the aerosol optical depth, were generated on the basis of a differential technique for all three campaigns, and their scientific significance is discussed.

  1. Radiation and Thermal Ageing of Nuclear Waste Glass

    Energy Technology Data Exchange (ETDEWEB)

    Weber, William J [ORNL

    2014-01-01

    The radioactive decay of fission products and actinides incorporated into nuclear waste glass leads to self-heating and self-radiation effects that may affect the stability, structure and performance of the glass in a closed system. Short-lived fission products cause significant self-heating for the first 600 years. Alpha decay of the actinides leads to self-radiation damage that can be significant after a few hundred years, and over the long time periods of geologic disposal, the accumulation of helium and radiation damage from alpha decay may lead to swelling, microstructural evolution and changes in mechanical properties. Four decades of research on the behavior of nuclear waste glass are reviewed.

  2. Mechanism of Hydrophilicity by Radiation-Induced Surface Activation

    Science.gov (United States)

    Honjo, Yoshio; Furuya, Masahiro; Takamasa, Tomoji; Okamoto, Koji

    When a metal oxide is irradiated by gamma rays, the irradiated surface becomes hydrophilic. This surface phenomenon is called as radiation-induced surface activation (RISA) hydrophilicity. In order to investigate gamma ray-induced and photoinduced hydrophilicity, the contact angles of water droplets on a titanium dioxide surface were measured in terms of irradiation intensity and time for gamma rays of cobalt-60 and for ultraviolet rays. Reciprocals of the contact angles increased in proportion to the irradiation time before the contact angles reached its super-hydrophilic state. The irradiation time dependency is equal to each other qualitatively. In addition, an effect of ambient gas was investigated. In pure argon gas, the contact angle remains the same against the irradiation time. This clearly indicates that certain humidity is required in ambient gas to take place of RISA hydrophilicity. A single crystal titanium dioxide (100) surface was analyzed by X-ray photoelectron spectrometry (XPS). After irradiation with gamma rays, a peak was found in the O1s spectrum, which indicates the adsorption of dissociative water to a surface 5-fold coordinate titanium site, and the formation of a surface hydroxyl group. We conclude that the RISA hydrophilicity is caused by chemisorption of the hydroxyl group on the surface.

  3. Laser-induced thermal desorption of aniline from silica surfaces

    Science.gov (United States)

    Voumard, Pierre; Zenobi, Renato

    1995-10-01

    A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109-1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.

  4. Nonlinear Radiative Heat Transfer in Blasius and Sakiadis Flows Over a Curved Surface

    Science.gov (United States)

    Naveed, M.; Abbas, Z.; Sajid, M.

    2017-01-01

    This study investigates the heat transfer characteristics for Blasius and Sakiadis flows over a curved surface coiled in a circle of radius R having constant curvature. Effects of thermal radiation are also analyzed for nonlinear Rosseland approximation which is valid for all values of the temperature difference between the fluid and the surface. The considered physical situation is represented by a mathematical model using curvilinear coordinates. Similar solutions of the developed partial differential equations are evaluated numerically using a shooting algorithm. Fluid velocity, skin-friction coefficient, temperature and local Nusselt number are the quantities of interest interpreted for the influence of pertinent parameters. A comparison of the present and the published data for a flat surface validates the obtained numerical solution for the curved geometry.

  5. Air Temperature estimation from Land Surface temperature and solar Radiation parameters

    Science.gov (United States)

    Lazzarini, Michele; Eissa, Yehia; Marpu, Prashanth; Ghedira, Hosni

    2013-04-01

    Air Temperature (AirT) is a fundamental parameter in a wide range of applications such as climate change studies, weather forecast, energy balance modeling, efficiency of Photovoltaic (PV) solar cells, etc. Air temperature data are generally obtained through regular measurements from meteorological stations. The distribution of these stations is normally sparse, so the spatial pattern of this parameter cannot be accurately estimated by interpolation methods. This work investigated the relationship between Air Temperature measured at meteorological stations and spatially contiguous measurements derived from Remote Sensing techniques, such as Land Surface Temperature (LST) maps, emissivity maps and shortwave radiation maps with the aim of creating a continuous map of AirT. For LST and emissivity, MSG-SEVIRI LST product from Land Surface Analysis Satellite Applications Facility (LSA-SAF) has been used. For shortwave radiation maps, an Artificial Neural Networks ensemble model has been developed and previously tested to create continuous maps from Global Horizontal Irradiance (GHI) point measurements, utilizing six thermal channels of MSG-SEVIRI. The testing sites corresponded to three meteorological stations located in the United Arab Emirates (UAE), where in situ measurements of Air Temperature were available. From the starting parameters, energy fluxes and net radiation have been calculated, in order to have information on the incoming and outgoing long-wave radiation and the incoming short-wave radiation. The preliminary analysis (day and Night measurements, cloud free) showed a strong negative correlation (0.92) between Outgoing long-wave radiation - GHI and LST- AirT, with a RMSE of 1.84 K in the AirT estimation from the initial parameters. Regression coefficients have been determined and tested on all the ground stations. The analysis also demonstrated the predominant impact of the incoming short-wave radiation in the AirT hourly variation, while the incoming

  6. Differential transformation method for studying flow and heat transfer due to stretching sheet embedded in porous medium with variable thickness, variable thermal conductivity, and thermal radiation

    Institute of Scientific and Technical Information of China (English)

    M M KHADER; A M MEGAHED

    2014-01-01

    This article presents a numerical solution for the flow of a Newtonian fluid over an impermeable stretching sheet embedded in a porous medium with the power law surface velocity and variable thickness in the presence of thermal radiation. The flow is caused by non-linear stretching of a sheet. Thermal conductivity of the fluid is assumed to vary linearly with temperature. The governing partial differential equa-tions (PDEs) are transformed into a system of coupled non-linear ordinary differential equations (ODEs) with appropriate boundary conditions for various physical parameters. The remaining system of ODEs is solved numerically using a differential transformation method (DTM). The effects of the porous parameter, the wall thickness parameter, the radiation parameter, the thermal conductivity parameter, and the Prandtl number on the flow and temperature profiles are presented. Moreover, the local skin-friction and the Nusselt numbers are presented. Comparison of the obtained numerical results is made with previously published results in some special cases, with good agreement. The results obtained in this paper confirm the idea that DTM is a powerful mathematical tool and can be applied to a large class of linear and non-linear problems in different fields of science and engineering.

  7. Thermal annealing of laser damage precursors on fused silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L

    2012-03-19

    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  8. Experimental Study on Coherence of Thermal Radiation of Thin Film Structures

    Institute of Scientific and Technical Information of China (English)

    LIANG Xin-Gang; HAN Mao-Hua

    2006-01-01

    @@ The spectral, angular and polarization characteristics of thermal radiation from plane-parallel Si films are studied experimentally. Pronounced spectral and angular peaks demonstrate the presence of thermal radiation coherence.Two kinds of multilayer films are designed to obtain favourable radiant properties. The ZrO2-Ge-ZnS film has a broad anti-reflection band in the wavelength range from 3.5μm to 8μm. The spectral and angular emissivities of the MgF2-ZnS-Ge-Al film are tremendously enhanced compared with those of an uncoated aluminium film.This can be helpful to the design of elements that generate controlled thermal radiation.

  9. Optimization of Thermal Neutron Converter in SiC Sensors for Spectral Radiation Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Krolikowski, Igor; Cetnar, Jerzy [Department of Nuclear Energy, Faculty of Energy and Fuels at AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Issa, Fatima; Ferrone, Raffaello; Ottaviani, Laurent [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231, 13397 Marseille Cedex 20 (France); Szalkai, Dora; Klix, Axel [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology, Karlsruhe 76344 (Germany); Vermeeren, Ludo [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Lyoussi, Abdalla [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France); Saenger, Richard [Etudes et Productions Schlumberger, Clamart (France)

    2015-07-01

    Optimization of the neutron converter in SiC sensors is presented. The sensors are used for spectral radiation measurements of thermal and fast neutrons and optionally gamma ray at elevated temperature in harsh radiation environment. The neutron converter, which is based on 10B, allows to detect thermal neutrons by means of neutron capture reaction. Two construction of the sensors were used to measure radiation in experiments. Sensor responses collected in experiments have been reproduced by the computer tool created by authors, it allows to validate the tool. The tool creates the response matrix function describing the characteristic of the sensors and it was used for detailed analyses of the sensor responses. Obtained results help to optimize the neutron converter in order to increase thermal neutron detection. Several enhanced construction of the sensors, which includes the neutron converter based on {sup 10}B or {sup 6}Li, were proposed. (authors)

  10. Assessing Consistency in Radiated Thermal Output of Beef Steers by Infrared Thermography

    Directory of Open Access Journals (Sweden)

    Nigel Cook

    2016-07-01

    Full Text Available Measurements of radiated thermal output are claimed to reflect the metabolic efficiency of mammals. This is important in food-producing animals because a measure of metabolic efficiency may translate to desirable characteristics, such as growth efficiency or residual feed intake, and permit the grouping of animals by metabolic characteristics that can be more precisely managed. This study addresses the question of whether radiated thermal parameters are characteristic of individual animals under normal and metabolically-challenging conditions. Consistency in radiated thermal output was demonstrated over a period of four weeks on condition that a sufficiently representative sample of measurements could be made on individual animals. The study provided evidence that infrared thermography could be used as an automated, rapid, and reliable tool for assessing thermoregulatory processes.

  11. Radiation and thermal polymerization of allyl(p-allylcarbonate) benzoate

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-V, D., E-mail: dlopez@siu.buap.m [Facultad de Ciencias Quimicas, Benemerita Universidad Autonoma de Puebla, Antiguo Edificio de la Fac. de Cs., Quimica. Av. San Claudio y Boulevard de la 14 sur, Col. San Manuel, Puebla, Pue., CP 72500 (Mexico); Herrera-G, A.M., E-mail: mherrera@uaeh.reduaeh.m [Centro de Inv. en Materiales y Metalurgia, UAEH. Km 4.5, C.U., CP 42184, Pachuca de S. Hidalgo (Mexico); Castillo-Rojas, S., E-mail: castillo@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 DF (Mexico)

    2011-03-15

    Bulk polymerization of novel allyl(p-allylcarbonate) benzoate was investigated using different sources of energy, such as gamma rays, ultraviolet rays as well as thermal polymerization. The poly(allyl(p-allylcarbonate) benzoate) obtained is a cross-linking, transparent, thermoset polycarbonate. Compositions of the monomer and the polycarbonate were analyzed by infrared spectroscopy, elemental analysis, and {sup 1}H NMR spectroscopy.

  12. Local thermal property analysis by scanning thermal microscopy of an ultrafine-grained copper surface layer produced by surface mechanical attrition treatment

    Energy Technology Data Exchange (ETDEWEB)

    Guo, F.A. [Suzhou Institute for Nonferrous Metals Processing Technology, No. 200 Shenxu Road, Suzhou Industrial Park, Suzhou 215021 (China) and Unite de Thermique et d' Analyse Physique, Laboratoire d' Energetique et d' Optique, Universite de Reims, BP 1039, 51687 Reims Cedex 2 (France)]. E-mail: guofuan@yahoo.com; JI, Y.L. [Suzhou Institute for Nonferrous Metals Processing Technology, No. 200 Shenxu Road, Suzhou Industrial Park, Suzhou 215021 (China); Trannoy, N. [Unite de Thermique et d' Analyse Physique, Laboratoire d' Energetique et d' Optique, Universite de Reims, BP 1039, 51687 Reims Cedex 2 (France); Lu, J. [LASMIS, Universite de Technologie de Troyes, 12 Rue Marie Curie, Troyes 10010 (France)

    2006-06-15

    Scanning thermal microscopy (SThM) was used to map thermal conductivity images in an ultrafine-grained copper surface layer produced by surface mechanical attrition treatment (SMAT). It is found that the deformed surface layer shows different thermal conductivities that strongly depend on the grain size of the microstructure: the thermal conductivity of the nanostructured surface layer decreases obviously when compared with that of the coarse-grained matrix of the sample. The role of the grain boundaries in thermal conduction is analyzed in correlation with the heat conduction mechanism in pure metal. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that SThM can be used as a tool for the thermal property and microstructural analysis of ultrafine-grained microstructures.

  13. Characters of surface deformation and surface wave in thermal capillary convection

    Institute of Scientific and Technical Information of China (English)

    DUAN; Li; KANG; Qi; HU; Wenrei

    2006-01-01

    In the field of fluid mechanics, free surface phenomena is one of the most important physical processes. In the present research work, the surface deformation and surface wave caused by temperature difference of sidewalls in a rectangular cavity have been investigated. The horizontal cross-section of the container is 52 mm×42 mm, and there is a silicon oil layer of height 3.5 mm in the experimental cavity. Temperature difference between the two side walls of the cavity is increased gradually, and the flow on the liquid layer will develop from stable convection to un-stable convection. An optical diagnostic system consisting of a modified Michelson interferometer and image processor has been developed for study of the surface deformation and surface wave of thermal capillary convection. The Fourier transformation method is used to interferometer fringe analysis. The quantitative results of surface deformation and surface wave have been calculated from a serial of the interference fringe patterns. The characters of surface deformation and surface wave have been obtained. They are related with temperature gradient and surface tension. Surface deformation is fluctuant with time, which shows the character of surface wave. The cycle period of the wave is 4.8 s, and the amplitudes are from 0 to 0.55 μm. The phase of the wave near the cool side of the cavity is opposite and correlative to that near the hot side. The present experiment proves that the surface wave of thermal capillary convection exists on liquid free surface, and it is wrapped in surface deformation.

  14. Thermal radiation and nonthermal radiation of the slowly changing dynamic Kerr-Newman black hole

    Institute of Scientific and Technical Information of China (English)

    Meng Qing-Miao; Wang Shuai; Jiang Ji-Jian; Deng De-Li

    2008-01-01

    Using the related formula of dynamic black hole, we have calculated the instantaneous radiation energy density of the slowly changing dynamic Kerr-Newman black hole. It is found that the instantaneous radiation energy density of a black hole is always proportional to the quartic of the temperature of the event horizon in the same direction. By using the Hamilton-Jacobin equation of scalar particles in the curved spacetime, the spontaneous radiation of the slowly changing dynamic Kerr-Newman black hole is studied. The energy condition for the occurrence of the spontaneous radiation is obtained.

  15. Systematics Study on Thermal Capture Radiation Cross Section for Fission Nuclides

    Institute of Scientific and Technical Information of China (English)

    TAO; Xi; WU; Hai-cheng; WANG; Ji-min

    2012-01-01

    <正>The research of the neutron capture radiation cross section is surveyed. The systematics of capture radiation cross section contains single energy cross section systematics, excitation function, and spectra systematics. This work gathers the experimental cross sections of actinide nuclei at the thermal energy, and evaluated data. 382 nuclei of ENDF/BⅦ.0, 398 nuclei of JENDL-4.0, 232 nuclei of CENDL-3.1, and the evaluation data of BNL are surveyed. Based on the evaluation, a set of capture cross sections for actinide nuclei at thermal energy is recommended.

  16. Investigation of thermal oxidative break-down of polyethylene films modified with grafted polyacrylonitrile. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Krul, L.P.; Gert, E.V. (Belorusskij Gosudarstvennyj Univ., Minsk)

    1981-11-01

    Thermal oxidative destruction of polyethylene (PE) films modified by radiation (..gamma..-radiation, dose rate is 0.56 Mrad/hr) liquid-phase graft polymerization of acrylonitrile (AN) has been studied. Comparative stability of grafted copolymers, homopolymers and mechanical mixtures of PE and PAN (polyacrylonitrile) to thermal oxidative destruction is studied using the derivatographic method. It is shown that graft of PAN considerably decelerates the development of oxidative and destructive processes in PE, at that, the efficiency of PE chain stabilization increases with the increase of grafted PAN amount. The sample with PAN content x=0.367 (in parts of the mass of grafted film) possesses the highest stability.

  17. Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

    Energy Technology Data Exchange (ETDEWEB)

    Pool, Vanessa L.; Dou, Benjia; Van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

    2017-01-17

    Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 degrees C, can be significantly reduced to 40 s at 170 degrees C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2.

  18. Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

    Science.gov (United States)

    Pool, Vanessa L.; Dou, Benjia; Van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

    2017-01-01

    Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 °C, can be significantly reduced to 40 s at 170 °C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2. PMID:28094249

  19. Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

    Science.gov (United States)

    Pool, Vanessa L.; Dou, Benjia; van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

    2017-01-01

    Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 °C, can be significantly reduced to 40 s at 170 °C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2.

  20. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    Science.gov (United States)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-07-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  1. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  2. The World Radiation Monitoring Center of the Baseline Surface Radiation Network: Status 2017

    Science.gov (United States)

    Driemel, Amelie; König-Langlo, Gert; Sieger, Rainer; Long, Charles N.

    2017-04-01

    The World Radiation Monitoring Center (WRMC) is the central archive of the Baseline Surface Radiation Network (BSRN). The BSRN was initiated by the World Climate Research Programme (WCRP) Working Group on Radiative Fluxes and began operations in 1992. One of its aims is to provide short and long-wave surface radiation fluxes of the best possible quality to support the research projects of the WCRP and other scientific projects. The high quality, uniform and consistent measurements of the BSRN network can be used to monitor the short- and long-wave radiative components and their changes with the best methods currently available, to validate and evaluate satellite-based estimates of the surface radiative fluxes, and to verify the results of global climate models. In 1992 the BSRN/WRMC started at ETH Zurich, Switzerland with 9 stations. Since 2007 the archive is hosted by the Alfred-Wegener-Institut (AWI) in Bremerhaven, Germany (http://www.bsrn.awi.de/) and comprises a network of currently 59 stations in contrasting climatic zones, covering a latitude range from 80°N to 90°S. Of the 59 stations, 23 offer the complete radiation budget (down- and upwelling short- and long-wave data). In addition to the ftp-service access instituted at ETH Zurich, the archive at AWI offers data access via PANGAEA - Data Publisher for Earth & Environmental Science (https://www.pangaea.de). PANGAEA guarantees the long-term availability of its content through a commitment of the operating institutions. Within PANGAEA, the metadata of the stations are freely available. To access the data itself an account is required. If the scientist accepts to follow the data release guidelines of the archive (http://bsrn.awi.de/data/conditions-of-data-release/) he or she can get an account from amelie.driemel@awi.de. Currently, more than 9,400 station months (>780 years) are available for interested scientists (see also https://dataportals.pangaea.de/bsrn/?q=LR0100 for an overview on available data

  3. Thermal instability of GaSb surface oxide

    Science.gov (United States)

    Tsunoda, K.; Matsukura, Y.; Suzuki, R.; Aoki, M.

    2016-05-01

    In the development of InAs/GaSb Type-II superlattice (T2SL) infrared photodetectors, the surface leakage current at the mesa sidewall must be suppressed. To achieve this requirement, both the surface treatment and the passivation layer are key technologies. As a starting point to design these processes, we investigated the GaSb oxide in terms of its growth and thermal stability. We found that the formation of GaSb oxide was very different from those of GaAs. Both Ga and Sb are oxidized at the surface of GaSb. In contrast, only Ga is oxidized and As is barely oxidized in the case of GaAs. Interestingly, the GaSb oxide can be formed even in DI water, which results in a very thick oxide film over 40 nm after 120 minutes. To examine the thermal stability, the GaSb native oxide was annealed in a vacuum and analyzed by XPS and Raman spectroscopy. These analyses suggest that SbOx in the GaSb native oxide will be reduced to metallic Sb above 300°C. To directly evaluate the effect of oxide instability on the device performance, a T2SL p-i-n photodetector was fabricated that has a cutoff wavelength of about 4 μm at 80 K. As a result, the surface leakage component was increased by the post annealing at 325°C. On the basis of these results, it is possible to speculate that a part of GaSb oxide on the sidewall surface will be reduced to metallic Sb, which acts as an origin of additional leakage current path.

  4. NON-THERMAL RADIATION FROM A NON-KERR-NEWMAN BLACK HOLE

    Institute of Scientific and Technical Information of China (English)

    谢实崇; 杨雪特; 杨树政; 林理彬

    2001-01-01

    In the spacetime of a charged spinning black hole, the distribution of particle energy levels has been studied. Near the event horizon of such a black hole a crossing of the particle energy levels exists, which leads to the occurrence of non-thermal radiation of the black hole. This quantum effect is non-thermal and also different from those of the Kerr and Kerr-Newman black holes.

  5. Abnormal thermal effects on the surface plasmon resonance of Ag nanoparticles on the surface of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Han; Ding, Ruiqiang [State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Li, Meicheng, E-mail: mcli@ncepu.edu.cn [State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Suzhou Institute, North China Electric Power University, Suzhou 215123 (China); Li, Yingfeng; Yang, Ganghai; Song, Dandan; Yu, Yue; Trevor, Mwenya [State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

    2015-06-01

    The thermal effects on the surface plasmon resonance (SPR) of Ag nanoparticles on the silicon surface have been studied. It is found that unusual blue shifts and narrowing of the SPR troughs occur as the temperature increases from 323 K to 363 K. At low temperature range (from 273 K to 323 K), the SPR troughs have the normal red shifts and broadening as in previous studies. The change of SPR is attributed to the thermal induced electron transport between particles and substrate, and is analyzed using samples with different particle sizes. This work reveals the mechanism of thermal effects on the plasmonic properties of Ag nanoparticles on the surface of silicon and offers useful information for designing of SPR devices. - Highlights: • Unusual blue shift of the SPR troughs is observed at 343 K. • Red shift of the SPR troughs is observed at 323 K. • The mechanism relies on the thermal induced surface electron transport. • Particle sizes play an important role in the change of the SPR troughs.

  6. Thermal hehavior of Surface Mounted Devices (SMD) packaging

    Science.gov (United States)

    Bloch, Werner; Moeller, Werner

    The thermal behavior of Surface Mounted Devices (SMD) packaging was investigated on an easily variable type. The effect of basic materials, chip carriers, and bonding, soldering, glueing and casting techniques was examined, considering the most important quantities, switching time and power. The test results show that cooling measures in the chip domain, such as chip bonding, chip casting, and chip carrier lining, are especially efficient for short switching times. The basic materials, even with heat sinks, become only important for longer switching times. The chip temperature of a conventional FR4/LCCC packaging was halved by the application of novel packaging materials, without changing the cooling mechanisms and the power.

  7. Surface interactions with electromagnetic spectrum relevant to solar thermal propulsion

    Science.gov (United States)

    Bonometti, Joseph Alexander John

    1997-11-01

    Elements of solar thermal rocket propulsion systems were experimentally examined to quantify the most significant physical parameters related to concentrating and capturing solar energy. A detailed examination of the sun's electromagnetic flux impingement upon a solar concentrator, redirection to a secondary reflector or refractor optic and absorption in an opaque cavity surface are presented. Research performed includes the analysis and design of a unique high temperature solar laboratory at the University of Alabama in Huntsville, its construction and subsequent operation. The entire facility was a prerequisite to conducting this experimental research and is the result of an initial two-year research effort. Four primary elements were experimentally examined and their relationship to the solar heating profile analyzed to optimize it for use in a solar thermal upper stage. The first was the comparison of concentrator types to define the incident energy profile with the conclusion that their type or quality was insignificant to the thermal heating profile in an absorber cavity. Rigid, thin-film and Fresnel concentrators were experimentally assessed. The second element was the evaluation of the absorber geometry's length-to-diameter ratio of a cylindrical cavity and included the addition of a secondary optic. The secondary optic was recognized as a requirement in the solar thermal rocket and could either improve the flux distribution on the cavity wall using a refractor with extractor rod, or hinder it as in using a parabolic reflector. The third was direct measurement of absorber material properties at elevated temperatures. Reflectivity, absorptivity and emissivity were determined for rhenium at 1000 Kelvin. The reflectivity measurements included both diffuse and specular reflection components and sample coupons of rhenium and niobium were shown to decrease in reflectivity when heated to temperatures approaching 1200 degrees Kelvin. The methodology was unique in

  8. Radiation injury of boron neutron capture therapy using mixed epithermal- and thermal neutron beams in patients with malignant glioma

    Energy Technology Data Exchange (ETDEWEB)

    Kageji, T. E-mail: kageji@clin.med.tokushima-u.ac.jp; Nagahiro, S.; Mizobuchi, Y.; Toi, H.; Nakagawa, Y.; Kumada, H

    2004-11-01

    The purpose of this study was to clarify the radiation injury in acute or delayed stage after boron neutron capture therapy (BNCT) using mixed epithermal- and thermal neutron beams in patients with malignant glioma. Eighteen patients with malignant glioma underwent mixed epithermal- and thermal neutron beam and sodium borocaptate between 1998 and 2004. The radiation dose (i.e. physical dose of boron n-alpha reaction) in the protocol used between 1998 and 2000 (Protocol A, n=8) prescribed a maximum tumor volume dose of 15 Gy. In 2001, a new dose-escalated protocol was introduced (Protocol B, n=4); it prescribes a minimum tumor volume dose of 18 Gy or, alternatively, a minimum target volume dose of 15 Gy. Since 2002, the radiation dose was reduced to 80-90% dose of Protocol B because of acute radiation injury. A new Protocol was applied to 6 glioblastoma patients (Protocol C, n=6). The average values of the maximum vascular dose of brain surface in Protocol A, B and C were 11.4{+-}4.2 Gy, 15.7{+-}1.2 and 13.9{+-}3.6 Gy, respectively. Acute radiation injury such as a generalized convulsion within 1 week after BNCT was recognized in three patients of Protocol B. Delayed radiation injury such as a neurological deterioration appeared 3-6 months after BNCT, and it was recognized in 1 patient in Protocol A, 5 patients in Protocol B. According to acute radiation injury, the maximum vascular dose was 15.8{+-}1.3 Gy in positive and was 12.6{+-}4.3 Gy in negative. There was no significant difference between them. According to the delayed radiation injury, the maximum vascular dose was 13.8{+-}3.8 Gy in positive and was 13.6{+-}4.9 Gy in negative. There was no significant difference between them. The dose escalation is limited because most patients in Protocol B suffered from acute radiation injury. We conclude that the maximum vascular dose does not exceed over 12 Gy to avoid the delayed radiation injury, especially, it should be limited under 10 Gy in the case that tumor

  9. Sensitivity of thermal inertia calculations to variations in environmental factors. [in mapping of Earth's surface by remote sensing

    Science.gov (United States)

    Kahle, A. B.; Alley, R. E.; Schieldge, J. P.

    1984-01-01

    The sensitivity of thermal inertia (TI) calculations to errors in the measurement or parameterization of a number of environmental factors is considered here. The factors include effects of radiative transfer in the atmosphere, surface albedo and emissivity, variations in surface turbulent heat flux density, cloud cover, vegetative cover, and topography. The error analysis is based upon data from the Heat Capacity Mapping Mission (HCMM) satellite for July 1978 at three separate test sites in the deserts of the western United States. Results show that typical errors in atmospheric radiative transfer, cloud cover, and vegetative cover can individually cause root-mean-square (RMS) errors of about 10 percent (with atmospheric effects sometimes as large as 30-40 percent) in HCMM-derived thermal inertia images of 20,000-200,000 pixels.

  10. Sensitivity of thermal inertia calculations to variations in environmental factors. [in mapping of Earth's surface by remote sensing

    Science.gov (United States)

    Kahle, A. B.; Alley, R. E.; Schieldge, J. P.

    1984-01-01

    The sensitivity of thermal inertia (TI) calculations to errors in the measurement or parameterization of a number of environmental factors is considered here. The factors include effects of radiative transfer in the atmosphere, surface albedo and emissivity, variations in surface turbulent heat flux density, cloud cover, vegetative cover, and topography. The error analysis is based upon data from the Heat Capacity Mapping Mission (HCMM) satellite for July 1978 at three separate test sites in the deserts of the western United States. Results show that typical errors in atmospheric radiative transfer, cloud cover, and vegetative cover can individually cause root-mean-square (RMS) errors of about 10 percent (with atmospheric effects sometimes as large as 30-40 percent) in HCMM-derived thermal inertia images of 20,000-200,000 pixels.

  11. Modeling the surface stored thermal energy in asphalt concrete pavements

    Directory of Open Access Journals (Sweden)

    Matić Bojan J.

    2016-01-01

    Full Text Available Regression analysis is used to develop models for minimal daily pavement surface temperature, using minimal daily air temperature, day of the year, wind speed and solar radiation as predictors, based on data from Awbari, Lybia,. Results were compared with existing SHRP and LTPP models. This paper also presents the models to predict surface pavement temperature depending on the days of the year using neural networks. Four annual periods are defined and new models are formulated for each period. Models using neural networks are formed on the basis of data gathered on the territory of the Republic of Serbia and are valid for that territory. [Projekat Ministarstva nauke Republike Srbije, br. TR 36017

  12. Surface and Electrical Properties of Electro-Coagulated Thermal Waste

    Science.gov (United States)

    Yesilkaya, S. S.; Okutan, M.; Içelli, O.; Yalçın, Z.

    2015-05-01

    The Electro-Coagulated Thermal Waste (ECTW) sample of the impedance spectroscopy investigation for electrical modulus and conductivity are presented. Electrical properties via temperature and frequency dependent impedance spectroscopy were investigated. Real and imaginary parts of electrical modulus were measured at various frequencies and a related Cole-Cole plot was acquired as well. The surface resistivity of the ECTW was measured by the four-point probe measurement technique, yielding a relatively high surface resistivity. As a result of this study, an effective building shielding material, which is a cost effective alternative, is proposed. The activation energy values were calculated from the Arrhenius plots at different frequencies. The transition region in this plot may be attributed to activation of ionic conductivity at lower temperatures.

  13. Simultaneous inversion of multiple land surface parameters from MODIS optical-thermal observations

    Science.gov (United States)

    Ma, Han; Liang, Shunlin; Xiao, Zhiqiang; Shi, Hanyu

    2017-06-01

    Land surface parameters from remote sensing observations are critical in monitoring and modeling of global climate change and biogeochemical cycles. Current methods for estimating land surface variables usually focus on individual parameters separately even from the same satellite observations, resulting in inconsistent products. Moreover, no efforts have been made to generate global products from integrated observations from the optical to Thermal InfraRed (TIR) spectrum. Particularly, Middle InfraRed (MIR) observations have received little attention due to the complexity of the radiometric signal, which contains both reflected and emitted radiation. In this paper, we propose a unified algorithm for simultaneously retrieving six land surface parameters - Leaf Area Index (LAI), Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), land surface albedo, Land Surface Emissivity (LSE), Land Surface Temperature (LST), and Upwelling Longwave radiation (LWUP) by exploiting MODIS visible-to-TIR observations. We incorporate a unified physical radiative transfer model into a data assimilation framework. The MODIS visible-to-TIR time series datasets include the daily surface reflectance product and MIR-to-TIR surface radiance, which are atmospherically corrected from the MODIS data using the Moderate Resolution Transmittance program (MODTRAN, ver. 5.0). LAI was first estimated using a data assimilation method that combines MODIS daily reflectance data and a LAI phenology model, and then the LAI was input to the unified radiative transfer model to simulate spectral surface reflectance and surface emissivity for calculating surface broadband albedo and emissivity, and FAPAR. LST was estimated from the MIR-TIR surface radiance data and the simulated emissivity, using an iterative optimization procedure. Lastly, LWUP was estimated using the LST and surface emissivity. The retrieved six parameters were extensively validated across six representative sites with

  14. Low Cost Radiator for Fission Power Thermal Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA GRC is developing fission power system technology for future space transportation and surface power applications. The early systems are envisioned in the 10 to...

  15. Low Cost Radiator for Fission Power Thermal Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA Glenn Research Center (GRC) is developing fission power system technology for future space transportation and surface power applications. The early systems are...

  16. Thermal evolution of a radiating anisotropic star with shear

    CERN Document Server

    Naidu, N F; Govinder, K S

    2006-01-01

    We study the effects of pressure anisotropy and heat dissipation in a spherically symmetric radiating star undergoing gravitational collapse. An exact solution of the Einstein field equations is presented in which the model has a Friedmann-like limit when the heat flux vanishes. The behaviour of the temperature profile of the evolving star is investigated within the framework of causal thermodynamics. In particular, we show that there are significant differences between the relaxation time for the heat flux and the relaxation time for the shear stress.

  17. Comment on "Universal Thermal Radiation Drag on Neutral Objects"

    CERN Document Server

    Maia-Neto, P A

    2004-01-01

    In a recent letter [Phys. Rev. Lett. 91, 220801 (2003)], V. Mkrtchian and co-workers calculated the radiation pressure force on a moving body, assuming the electromagnetic field to be at temperature $T,$ and the velocity to be much smaller than $c.$ They considered both dielectrics and conductors, and related the effect to Casimir dissipative forces. Here we claim that their approach may only apply in the Rayleigh-Ganz scattering regime, which corresponds to very small particles and/or electromagnetically rarefied media. Moreover, we argue that their interpretation in terms of the Casimir effect is misleading, since vacuum fluctuations do not contribute in the (implicitly assumed) regime of uniform motion.

  18. Simultaneous Thermal and Gamma Radiation Aging of Cable Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Fifield, Leonard S.; Liu, Shuaishuai; Bowler, Nicola

    2016-12-19

    Polymers used in nuclear power plant electrical cable systems experience aging and degradation over time due to environmental stress including heat and gamma irradiation. Prediction of long-term cable performance has been based on results of short-term accelerated laboratory aging studies, but questions remain regarding the correlation of accelerated aging to long-term, in-plant aging. This work seeks to increase understanding of the combined effects of heat and radiation on cable polymer material aging toward addressing these questions.

  19. A nonventing cooling system for space environment extravehicular activity, using radiation and regenerable thermal storage

    Science.gov (United States)

    Bayes, Stephen A.; Trevino, Luis A.; Dinsmore, Craig E.

    1988-01-01

    This paper outlines the selection, design, and testing of a prototype nonventing regenerable astronaut cooling system for extravehicular activity space suit applications, for mission durations of four hours or greater. The selected system consists of the following key elements: a radiator assembly which serves as the exterior shell of the portable life support subsystem backpack; a layer of phase change thermal storage material, n-hexadecane paraffin, which acts as a regenerable thermal capacitor; a thermoelectric heat pump; and an automatic temperature control system. The capability for regeneration of thermal storage capacity with and without the aid of electric power is provided.

  20. Impact of buildings on surface solar radiation over urban Beijing

    Science.gov (United States)

    Zhao, Bin; Liou, Kuo-Nan; Gu, Yu; He, Cenlin; Lee, Wee-Liang; Chang, Xing; Li, Qinbin; Wang, Shuxiao; Tseng, Hsien-Liang R.; Leung, Lai-Yung R.; Hao, Jiming

    2016-05-01

    The rugged surface of an urban area due to varying buildings can interact with solar beams and affect both the magnitude and spatiotemporal distribution of surface solar fluxes. Here we systematically examine the impact of buildings on downward surface solar fluxes over urban Beijing by using a 3-D radiation parameterization that accounts for 3-D building structures vs. the conventional plane-parallel scheme. We find that the resulting downward surface solar flux deviations between the 3-D and the plane-parallel schemes are generally ±1-10 W m-2 at 800 m grid resolution and within ±1 W m-2 at 4 km resolution. Pairs of positive-negative flux deviations on different sides of buildings are resolved at 800 m resolution, while they offset each other at 4 km resolution. Flux deviations from the unobstructed horizontal surface at 4 km resolution are positive around noon but negative in the early morning and late afternoon. The corresponding deviations at 800 m resolution, in contrast, show diurnal variations that are strongly dependent on the location of the grids relative to the buildings. Both the magnitude and spatiotemporal variations of flux deviations are largely dominated by the direct flux. Furthermore, we find that flux deviations can potentially be an order of magnitude larger by using a finer grid resolution. Atmospheric aerosols can reduce the magnitude of downward surface solar flux deviations by 10-65 %, while the surface albedo generally has a rather moderate impact on flux deviations. The results imply that the effect of buildings on downward surface solar fluxes may not be critically significant in mesoscale atmospheric models with a grid resolution of 4 km or coarser. However, the effect can play a crucial role in meso-urban atmospheric models as well as microscale urban dispersion models with resolutions of 1 m to 1 km.

  1. Impact of buildings on surface solar radiation over urban Beijing

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bin; Liou, Kuo-Nan; Gu, Yu; He, Cenlin; Lee, Wee-Liang; Chang, Xing; Li, Qinbin; Wang, Shuxiao; Tseng, Hsien-Liang R.; Leung, Lai-Yung R.; Hao, Jiming

    2016-05-12

    The rugged surface of an urban area due to varying buildings can interact with solar beams and affect both the magnitude and spatiotemporal distribution of surface solar fluxes. Here we systematically examine the impact of buildings on downward surface solar fluxes over urban Beijing by using a 3-D radiation parameterization that accounts for 3-D building structures vs. the conventional plane-parallel scheme. We find that the resulting downward surface solar flux deviations between the 3-D and the plane-parallel schemes are generally ±1–10 W m-2 at 800 m grid resolution and within ±1 W m-2 at 4 km resolution. Pairs of positive–negative flux deviations on different sides of buildings are resolved at 800 m resolution, while they offset each other at 4 km resolution. Flux deviations from the unobstructed horizontal surface at 4 km resolution are positive around noon but negative in the early morning and late afternoon. The corresponding deviations at 800 m resolution, in contrast, show diurnal variations that are strongly dependent on the location of the grids relative to the buildings. Both the magnitude and spatiotemporal variations of flux deviations are largely dominated by the direct flux. Furthermore, we find that flux deviations can potentially be an order of magnitude larger by using a finer grid resolution. Atmospheric aerosols can reduce the magnitude of downward surface solar flux deviations by 10–65 %, while the surface albedo generally has a rather moderate impact on flux deviations. The results imply that the effect of buildings on downward surface solar fluxes may not be critically significant in mesoscale atmospheric models with a grid resolution of 4 km or coarser. However, the effect can play a crucial role in meso-urban atmospheric models as well as microscale urban dispersion models with resolutions of 1 m to 1 km.

  2. Radiative thermal escape in intermediate band solar cells

    Directory of Open Access Journals (Sweden)

    A. Luque

    2011-06-01

    Full Text Available To achieve high efficiency, the intermediate band (IB solar cell must generate photocurrent from sub-bandgap photons at a voltage higher than that of a single contributing sub-bandgap photon. To achieve the latter, it is necessary that the IB levels be properly isolated from the valence and conduction bands. We prove that this is not the case for IB cells formed with the confined levels of InAs quantum dots (QDs in GaAs grown so far due to the strong density of internal thermal photons at the transition energies involved. To counteract this, the QD must be smaller.

  3. Using Thermal Radiation in Detection of Negative Obstacles

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.

    2009-01-01

    A method of automated detection of negative obstacles (potholes, ditches, and the like) ahead of ground vehicles at night involves processing of imagery from thermal-infrared cameras aimed at the terrain ahead of the vehicles. The method is being developed as part of an overall obstacle-avoidance scheme for autonomous and semi-autonomous offroad robotic vehicles. The method could also be applied to help human drivers of cars and trucks avoid negative obstacles -- a development that may entail only modest additional cost inasmuch as some commercially available passenger cars are already equipped with infrared cameras as aids for nighttime operation.

  4. Thermal anomaly at the Earth's surface associated with a lava tube

    Science.gov (United States)

    Piombo, Antonello; Di Bari, Marco; Tallarico, Andrea; Dragoni, Michele

    2016-10-01

    Lava tubes are frequently encountered in volcanic areas. The formation of lava tubes has strong implications on the volcanic hazard during effusive eruptions. The thermal dissipation of lava flowing in a tube is reduced in respect to the lava flowing in an open channel so the lava may threaten areas that would not be reached by flows in open channels: for this reason it is important to detect the presence of lava tubes. In this work we propose a model to detect the presence and the characteristics of lava tubes by their thermal footprint at the surface. We model numerically the temperature distribution and the heat flow, both in the steady and the transient state, and we take into account the principal thermal effects due to the presence of an active lava tube, i.e. the conduction to the ground and the atmosphere, the convection and the radiation in the atmosphere. We assume that lava fluid is at high temperature, in motion inside a sloping tube under the gravity force. The thermal profile across the tube direction, in particular the width of the temperature curve, allows to evaluate the depth of the tube. The values of maximum temperature and of tube depth allow to estimate the area of the tube section. The shape of the temperature curve and its asymmetry can give information about the geometry of the tube. If we observe volcanic areas at different times by thermal cameras, we can detect anomalies and evaluate their causes during an eruption; in particular, we can evaluate whether they are due to active lava flows or not and what is their state. For lava tubes, we can connect thermal anomalies with lava tube position, characteristics and state.

  5. Interpretation of Impact Features on the Surface of the WFPC-2 Radiator

    Science.gov (United States)

    Anz-Meador, P. D.; Christiansen, Eric L.; Kou, J.-C.

    2011-01-01

    An examination of the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC-2) radiator assembly was conducted at NASA Goddard Space Flight Center (GSFC) during the summer of 2009. Immediately apparent was the predominance of impact features resident only in the thermal paint layer; similar phenomenology was observed during a prior survey of the WFPC-1 radiator. As well, larger impact features displayed spallation zones, darkened areas, and other features not encountered in impacts onto bare surfaces. Whereas the characterization of impact features by depth and diameter on unpainted surfaces has been long established, the mitigation provided by the painted layer presented a challenge to further analysis of the WFPC-2 features; a literature search revealed no systematic characterization of the ballistic limit equations of painted or coated surfaces. In order to characterize the impactors responsible for the observed damage, an understanding of the cratering and spallation phenomenology of the painted surface was required. To address that challenge, NASA sponsored a series of hypervelocity calibration shots at the White Sands Test Facility (WSTF). This effort required the following activities: the production, painting, and artificial ageing of test coupons in a manner similar to the actual radiator; the determination of the test matrix parameters projectile diameter and material (mass density), impact velocity, and impact angle, so as to enable both an adequate characterization of the impact by projectile and impact geometry and support hydrocode modeling to fill in and extend the applicability of the calibration shots; the selection of suitable projectiles; logistics; and an analysis of feature characteristics upon return of the coupons. This paper reports the results of the test campaign and presents ballistic limit equations for painted surfaces. We also present initial results of our interpretation methodologies.

  6. Changes in biologically active ultraviolet radiation reaching the Earth's surface.

    Science.gov (United States)

    McKenzie, Richard L; Björn, Lars Olof; Bais, Alkiviadis; Ilyasad, Mohammad

    2003-01-01

    Since publication of the 1998 UNEP Assessment, there has been continued rapid expansion of the literature on UV-B radiation. Many measurements have demonstrated the inverse relationship between column ozone amount and UV radiation, and in a few cases long-term increases due to ozone decreases have been identified. The quantity, quality and availability of ground-based UV measurements relevant to assessing the environmental impacts of ozone changes continue to improve. Recent studies have contributed to delineating regional and temporal differences due to aerosols, clouds, and ozone. Improvements in radiative transfer modelling capability now enable more accurate characterization of clouds, snow-cover, and topographical effects. A standardized scale for reporting UV to the public has gained wide acceptance. There has been increased use of satellite data to estimate geographic variability and trends in UV. Progress has been made in assessing the utility of satellite retrievals of UV radiation by comparison with measurements at the Earth's surface. Global climatologies of UV radiation are now available on the Internet. Anthropogenic aerosols play a more important role in attenuating UV irradiances than has been assumed previously, and this will have implications for the accuracy of UV retrievals from satellite data. Progress has been made inferring historical levels of UV radiation using measurements of ozone (from satellites or from ground-based networks) in conjunction with measurements of total solar radiation obtained from extensive meteorological networks. We cannot yet be sure whether global ozone has reached a minimum. Atmospheric chlorine concentrations are beginning to decrease. However, bromine concentrations are still increasing. While these halogen concentrations remain high, the ozone layer remains vulnerable to further depletion from events such as volcanic eruptions that inject material into the stratosphere. Interactions between global warming and

  7. Sensitivity enhancement of surface thermal lens technique with a short-wavelength probe beam: Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaorong [Institute of Optics and Electronics, Chinese Academy of Sciences and Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Bincheng [Institute of Optics and Electronics, Chinese Academy of Sciences and Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209 (China)

    2015-02-15

    Surface thermal lens is a highly sensitive photothermal technique to measure low absorption losses of various solid materials. In such applications, the sensitivity of surface thermal lens is a key parameter for measuring extremely low absorption. In this paper, we experimentally investigated the influence of probe beam wavelength on the sensitivity of surface thermal lens for measuring the low absorptance of optical laser components. Three probe lasers with wavelength 375 nm, 633 nm, and 1570 nm were used, respectively, to detect the surface thermal lens amplitude of a highly reflective coating sample excited by a cw modulated Gaussian beam at 1064 nm. The experimental results showed that the maximum amplitude of surface thermal lens signal obtained at corresponding optimized detection distance was inversely proportional to the wavelength of the probe beam, as predicted by previous theoretical model. The sensitivity of surface thermal lens could, therefore, be improved by detecting surface thermal lens signal with a short-wavelength probe beam.

  8. The physics of non-thermal radiation in microquasars

    CERN Document Server

    Bosch-Ramon, V

    2008-01-01

    Microquasars are binary systems that harbor a normal star and a compact object (black-hole or neutron star), and show relativistic outflows (or jets). The matter that forms these jets is of likely stellar origin, previously expelled from the star and trapped in the potential well of the compact object. This matter is accreted by the compact object, forming a disk due to its angular momentum, and is eventually ejected in the form of a bipolar outflow (the jets), which generates radio emission and could also be a very high-energy emitter. To study and understand the radiation from microquasars, there is a set of elements that can play a major role and are to be taken into account: the photons and the expelled matter from the star in the case of high-mass systems; the accreted matter radiation; the jet; the magnetic field carried by the jet or filling the binary system; and the medium surrounding the microquasar at large scales (~pc). In this lecture, we consider these elements of the microquasar scenario and br...

  9. On-surface radiation condition for multiple scattering of waves

    CERN Document Server

    Acosta, Sebastian

    2013-01-01

    The formulation of the on-surface radiation condition (OSRC) is extended to handle wave scattering problems in the presence of multiple obstacles. The new multiple-OSRC simultaneously accounts for the outgoing behavior of the wave fields, as well as, the multiple wave reflections between the obstacles. Like boundary integral equations (BIE), this method leads to a reduction in dimensionality (from volume to surface) of the discretization region. However, as opposed to BIE, the proposed technique leads to boundary integrals with smooth kernels. In addition, under appropriate conditions, this approach leads to approximate explicit (up to numerical integration) formulas for the solution, avoiding the need to invert any operator or matrix. As a result, the computational effort is significantly reduced. This approach may serve as a fast method to explore parameter-spaces or as an inexpensive pre-conditioner for Krylov iterative solutions of BIE.

  10. On surface Raman scattering and luminescence radiation in boron carbide.

    Science.gov (United States)

    Werheit, H; Filipov, V; Schwarz, U; Armbrüster, M; Leithe-Jasper, A; Tanaka, T; Shalamberidze, S O

    2010-02-01

    The discrepancy between Raman spectra of boron carbide obtained by Fourier transform Raman and conventional Raman spectrometry is systematically investigated. While at photon energies below the exciton energy (1.560 eV), Raman scattering of bulk phonons of boron carbide occurs, photon energies exceeding the fundamental absorption edge (2.09 eV) evoke additional patterns, which may essentially be attributed to luminescence or to the excitation of Raman-active processes in the surface region. The reason for this is the very high fundamental absorption in boron carbide inducing a very small penetration depth of the exciting laser radiation. Raman excitations essentially restricted to the boron carbide surface region yield spectra which considerably differ from bulk phonon ones, thus indicating structural modifications.

  11. Thermal radiation effect on the extinction properties of electric arcs in HV circuit breakers

    Directory of Open Access Journals (Sweden)

    Ziani Abderrahmane

    2009-01-01

    Full Text Available During the formation of the electric arc at the opening of a high voltage circuit breaker, the generated plasma will be the seat of a very important thermal exchange. Models founded only on conduction and convection thermal transfers don't reproduce the whole thermal exchanges that are governing the extinction process. This paper is devoted to the development of a model of the electric arc extinction in a high voltage circuit breaker taking in account the thermal radiation of the plasma, in addition to the conduction and convection phenomena. The Stefan-Boltzman equation is coupled with the heat equation, and both equations are solved simultaneously in order to follow the evolution of the arc voltage and the conductance of the thermal plasma. The obtained results are found in good agreement with experimental recordings.

  12. Interplay of radiative and nonradiative transitions in surface hopping with radiation-molecule interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bajo, Juan José [Departamento de Química-Física I, Universidad Complutense de Madrid, 28040 Madrid (Spain); Granucci, Giovanni, E-mail: giovanni.granucci@unipi.it; Persico, Maurizio [Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via Risorgimento 35, 56126 Pisa (Italy)

    2014-01-28

    We implemented a method for the treatment of field induced transitions in trajectory surface hopping simulations, in the framework of the local diabatization scheme, especially suited for on-the-fly dynamics. The method is applied to a simple one-dimensional model with an avoided crossing and compared with quantum wavepacket dynamics. The results show the importance of introducing a proper decoherence correction to surface hopping, in order to obtain meaningful results. Also the energy conservation policy of standard surface hopping must be revised: in fact, the quantum wavepacket energetics is well reproduced if energy absorption/emission is allowed for in the hops determined by radiation-molecule coupling. To our knowledge, this is the first time the issues of decoherence and energy conservation have been analyzed in depth to devise a mixed quantum-classical method for dynamics with molecule-field interactions.

  13. Safe, Non-Corrosive Dielectric Fluid for Stagnating Radiator Thermal Control System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Paragon proposes to develop a single-loop, non-toxic, stagnating active pumped loop thermal control design for NASA's Orion or Lunar Surface Access Module (LSAM)...

  14. Heat gain from thermal radiation through protective clothing with different insulation, reflectivity and vapour permeability

    NARCIS (Netherlands)

    Bröde, P.; Kuklane, K.; Candas, V.; Hartog, E.A. den; Griefahn, B.; Holmér, I.; Meinander, H.; Nocker, W.; Richards, M.; Havenith, G.

    2010-01-01

    The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considere

  15. Radiation and Thermal Analysis of Superconducting Quadrupoles in the Interaction Region of Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Drozhdin, A.I.; Kashikhin, V.V.; Kashikhin, V.S.; Lopes, M.L.; Mokhov, N.V.; Zlobin, A.V.; /Fermilab; Seryi, Andrei; /SLAC

    2011-10-14

    Radiation heat deposition in the superconducting magnets of the Interaction Region (IR) of a linear collider can be a serious issue that limits the magnet operating margins and shortens the material lifetime. Radiation and thermal analyses of the IR quadrupoles in the incoming and extraction beam lines of the ILC are performed in order to determine the magnet limits. This paper presents an analysis of the radial, azimuthal and longitudinal distributions of heat deposition in the incoming and disrupted beam doublets. Operation margins of the magnets based on NbTi superconductor are calculated and compared. The radiation and thermal analysis of the ILC IR quadrupoles based on Rutherford type cables was performed. It was found that the peak radiation heat deposition takes place in the second extraction quadrupole QFEX2. The maximum power density in the coil is {approx}17mW/g. This is rather high, comparing to the proton machines (LHC). However, the fast radial decay of the heat deposition together with the high thermal conductivity of the Rutherford type cable limits the coil temperatures to a moderate level. It was determined that both 2-layer and 4-layer QFEX2 magnet designs have thermal margins of a factor of {approx}4 at the nominal gradient of 31.3 T/m. Because of the large margins, these magnets can easily accommodate possible changes in the IR optics and heat deposition levels.

  16. On computations for thermal radiation in MHD channel flow with heat and mass transfer.

    Science.gov (United States)

    Hayat, T; Awais, M; Alsaedi, A; Safdar, Ambreen

    2014-01-01

    This study examines the simultaneous effects of heat and mass transfer on the three-dimensional boundary layer flow of viscous fluid between two infinite parallel plates. Magnetohydrodynamic (MHD) and thermal radiation effects are present. The governing problems are first modeled and then solved by homotopy analysis method (HAM). Influence of several embedded parameters on the velocity, concentration and temperature fields are described.

  17. Non-Thermal Corrections to Hawking Radiation Versus the Information Paradox

    CERN Document Server

    Dvali, Gia

    2015-01-01

    We provide a model-independent argument indicating that for a black hole of entropy N the non-thermal deviations from Hawking radiation, per each emission time, are of order 1/N, as opposed to exp(-N). This fact abolishes the standard a priory basis for the information paradox.

  18. Effect of Thermal Radiation on the Integrity of Pressurized Aircraft Evacuation Slides and Slide Materials

    Science.gov (United States)

    1981-03-01

    Pres sureI 19. Security Classif. (of this reort) 20. Security Classif. (of this pegs ) 21. No. of Pagos J~ ’E tce UnlsiidUnclassified :179 Ffig DOT F... deta from the new integrity of pressurized evacuation laboratory test method. slide materials exposed to thermal radiation; (2) develop a practical

  19. Progress Towards Optimally Efficient Schemes for Monte Carlo Thermal Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Smedley-Stevenson, R P; Brooks III, E D

    2007-09-26

    In this summary we review the complementary research being undertaken at AWE and LLNL aimed at developing optimally efficient algorithms for Monte Carlo thermal radiation transport based on the difference formulation. We conclude by presenting preliminary results on the application of Newton-Krylov methods for solving the Symbolic Implicit Monte Carlo (SIMC) energy equation.

  20. Polylogarithmic representation of radiative and thermodynamic properties of thermal radiation in a given spectral range: I. Blackbody radiation

    CERN Document Server

    Fisenko, Anatoliy I

    2014-01-01

    Using polylogarithm functions the exact analytical expressions for the radiative and thermodynamic properties of blackbody radiation, such as the Wien displacement law, Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies are constructed. The obtained expressions allow us to tabulate these functions in various finite frequency bands at different temperatures for practical applications. As an example, the radiative and thermodynamic functions using experimental data for the monopole spectrum of the Cosmic Microwave Background (CMB) radiation measured by the COBE FIRAS instrument in the 60 - 600 GHz frequency interval at the temperature T = 2.725 K are calculated. The expressions obtained for the radiative and thermodynamic functions can be easily presented in wavelength and wavenumber domains.

  1. Effects of Radiation and Chemical Reaction on MHD Convective Flow over a Permeable Stretching Surface with Suction and Heat Generation

    Directory of Open Access Journals (Sweden)

    Penem Mohan KRISNA

    2014-03-01

    Full Text Available In this study, we analyze the effects of thermal radiation and chemical reaction on the steady 2 dimensional stagnation point flow of a viscous incompressible electrically conducting fluid over a stretching surface, with suction and heat generation. The partial differential equations governing the flow are solved numerically by using the shooting technique. The effects of various parameters on velocity, temperature, and concentration profiles, as well as Nusselt number, Skin friction coefficient, and Sherwood number, are examined, and presented graphically and through tables. It is found that velocity, temperature, and rate of heat transfer of the fluid are influenced more by radiation and chemical reaction parameters, along with applied magnetic field.

  2. Effect of a Temperature Mode of Radiation-thermal Sintering the Structure and Magnetic Properties of Mn-Zn-ferrites

    Directory of Open Access Journals (Sweden)

    V.G. Kostishyn

    2015-12-01

    Full Text Available 2000NM Mn-Zn-ferrites have been produced by radiation-thermal sintering (RTS. We have studied the effect of RTS on the electromagnetic properties of ferrites. X-ray diffraction have been used to investigate general aspects of phase transformations during the radiation-thermal sintering of green compacts.

  3. A conductive surface coating for Si-CNT radiation detectors

    Science.gov (United States)

    Valentini, Antonio; Valentini, Marco; Ditaranto, Nicoletta; Melisi, Domenico; Aramo, Carla; Ambrosio, Antonio; Casamassima, Giuseppe; Cilmo, Marco; Fiandrini, Emanuele; Grossi, Valentina; Guarino, Fausto; Angela Nitti, Maria; Passacantando, Maurizio; Santucci, Sandro; Ambrosio, Michelangelo

    2015-08-01

    Silicon-Carbon Nanotube radiation detectors need an electrically conductive coating layer to avoid the nanotube detachment from the silicon substrate and uniformly transmit the electric field to the entire nanotube active surface. Coating material must be transparent to the radiation of interest, and must provide the drain voltage necessary to collect charges generated by incident photons. For this purpose various materials have been tested and proposed in photodetector and photoconverter applications. In this article interface properties and electrical contact behavior of Indium Tin Oxide films on Carbon Nanotubes have been analyzed. Ion Beam Sputtering has been used to grow the transparent conductive layer on the nanotubes. The films were deposited at room temperature with Oxygen/Argon mixture into the sputtering beam, at fixed current and for different beam energies. Optical and electrical analyses have been performed on films. Surface chemical analysis and in depth profiling results obtained by X-ray Photoelectron Spectroscopy of the Indium Tin Oxide layer on nanotubes have been used to obtain the interface composition. Results have been applied in photodetectors realization based on multi wall Carbon Nanotubes on silicon.

  4. A conductive surface coating for Si-CNT radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, Antonio, E-mail: antonio.valentini@ba.infn.it [Dipartimento di Fisica, Università degli Studi di Bari, Via Orabona 4, 70125 Bari (Italy); Valentini, Marco [INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Ditaranto, Nicoletta [Dipartimento di Chimica, Università degli Studi di Bari, Via Amendola 173, 70126 Bari (Italy); Melisi, Domenico [INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Aramo, Carla, E-mail: aramo@na.infn.it [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Ambrosio, Antonio [CNR-SPIN U.O.S. di Napoli and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Casamassima, Giuseppe [Dipartimento di Fisica, Università degli Studi di Bari, Via Orabona 4, 70125 Bari (Italy); INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Cilmo, Marco [INFN, Sezione di Napoli, and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Fiandrini, Emanuele [INFN, Sezione di Perugia, and Dipartimento di Fisica, Università degli Studi di Perugia, Piazza Università 1, 06100 Perugia (Italy); Grossi, Valentina [INFN, Sezione di L’Aquila, and Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio 10 Coppito, 67100 L’Aquila (Italy); and others

    2015-08-01

    Silicon–Carbon Nanotube radiation detectors need an electrically conductive coating layer to avoid the nanotube detachment from the silicon substrate and uniformly transmit the electric field to the entire nanotube active surface. Coating material must be transparent to the radiation of interest, and must provide the drain voltage necessary to collect charges generated by incident photons. For this purpose various materials have been tested and proposed in photodetector and photoconverter applications. In this article interface properties and electrical contact behavior of Indium Tin Oxide films on Carbon Nanotubes have been analyzed. Ion Beam Sputtering has been used to grow the transparent conductive layer on the nanotubes. The films were deposited at room temperature with Oxygen/Argon mixture into the sputtering beam, at fixed current and for different beam energies. Optical and electrical analyses have been performed on films. Surface chemical analysis and in depth profiling results obtained by X-ray Photoelectron Spectroscopy of the Indium Tin Oxide layer on nanotubes have been used to obtain the interface composition. Results have been applied in photodetectors realization based on multi wall Carbon Nanotubes on silicon. - Highlights: • ITO was deposited by Ion Beam Sputtering on MWCNT. • ITO on CNT makes an inter-diffusion layer of the order of one hundred nanometers. • Improvements of quantum efficiency of photon detectors based on CNT with ITO.

  5. Thermal radiation of heterogeneous combustion products in the model rocket engine plume

    Science.gov (United States)

    Kuzmin, V. A.; Maratkanova, E. I.; Zagray, I. A.; Rukavishnikova, R. V.

    2015-05-01

    The work presents a method of complex investigation of thermal radiation emitted by heterogeneous combustion products in the model rocket engine plume. Realization of the method has allowed us to obtain full information on the results in all stages of calculations. Dependence of the optical properties (complex refractive index), the radiation characteristics (coefficients and cross sections) and emission characteristics (flux densities, emissivity factors) of the main determining factors and parameters was analyzed. It was found by the method of computational experiment that the presence of the gaseous phase in the combustion products causes a strongly marked selectivity of emission, due to which the use of gray approximation in the calculation of thermal radiation is unnecessary. The influence of the optical properties, mass fraction, the function of particle size distribution, and the temperature of combustion products on thermal radiation in the model rocket engine plume was investigated. The role of "spotlight" effect-increasing the amount of energy of emission exhaust combustion products due to scattering by condensate particles radiation from the combustion chamber-was established quantitatively.

  6. Tunable wideband-directive thermal emission from SiC surface using bundled graphene sheets

    Science.gov (United States)

    Inampudi, Sandeep; Mosallaei, Hossein

    2017-09-01

    Coherent thermal radiation emitters based on diffraction gratings inscribed on surface of a polar material, such as silicon carbide, always possess high angular dispersion resulting in wideband-dispersive or monochromatic-directive emission. In this paper, we identify roots of the high angular dispersion as the rapid surface phonon polariton (SPhP) resonance of the material surface and the misalignment of the dispersion curve of the diffraction orders of the grating with respect to light line. We minimize the rapid variation of SPhP resonance by compensating the material dispersion using bundled graphene sheets and mitigate the misalignment by a proper choice of the grating design. Utilizing a modified form of rigorous coupled wave analysis to simultaneously incorporate atomic-scale graphene sheets and bulk diffraction gratings, we accurately compute the emissivity profiles of the composite structure and demonstrate reduction in the angular dispersion of thermal emission from as high as 30∘ to as low as 4∘ in the SPhP dominant wavelength range of 11-12 μ m . In addition, we demonstrate that the graphene sheets via their tunable optical properties allow a fringe benefit of dynamical variation of the angular dispersion to a wide range.

  7. Relativistic stellar jets: dynamics and non-thermal radiation

    Directory of Open Access Journals (Sweden)

    Bosch-Ramon Valentí

    2013-12-01

    Full Text Available Relativistic stellar jets, produced in binary systems called microquasars, propagate through media with different spatial scales releasing their energy in the form of work and radiation from radio to gamma rays. There are several medium-interaction scenarios that these jets can face. In particular, in relativistic stellar jets the presence of a star is an unavoidable element whose importance deserves to be studied. In the case of highmass stars, their powerful winds are likely to interact dynamically with the jet, but also low-mass stars in the post-main sequence phase can present dense winds that will act as an obstacle for the jet propagation. In this work, we present a semi-qualitative discussion on the importance of the star for the evolution of relativistic stellar jets.

  8. Thermal control of sequential on-surface transformation of a hydrocarbon molecule on a copper surface

    Science.gov (United States)

    Kawai, Shigeki; Haapasilta, Ville; Lindner, Benjamin D.; Tahara, Kazukuni; Spijker, Peter; Buitendijk, Jeroen A.; Pawlak, Rémy; Meier, Tobias; Tobe, Yoshito; Foster, Adam S.; Meyer, Ernst

    2016-09-01

    On-surface chemical reactions hold the potential for manufacturing nanoscale structures directly onto surfaces by linking carbon atoms in a single-step reaction. To fabricate more complex and functionalized structures, the control of the on-surface chemical reactions must be developed significantly. Here, we present a thermally controlled sequential three-step chemical transformation of a hydrocarbon molecule on a Cu(111) surface. With a combination of high-resolution atomic force microscopy and first-principles computations, we investigate the transformation process in step-by-step detail from the initial structure to the final product via two intermediate states. The results demonstrate that surfaces can be used as catalysing templates to obtain compounds, which cannot easily be synthesized by solution chemistry.

  9. Thermal radiation of Er doped dielectric crystals: Probing the range of applicability of the Kirchhoff law

    CERN Document Server

    Tanyi, Ekembu K; Narimanov, Evgenii E; Noginov, M A

    2016-01-01

    The Kirchhoff law of thermal radiation, relating emissivity {\\epsilon} and absorptance {\\alpha}, has been originally formulated for opaque bodies in thermodynamic equilibrium with the environment. However, in many systems of practical importance, both assumptions are often not satisfied. In this work, we revisit the century-old law and examine the limits of its applicability in an example of Er:YAG and Er:YLF dielectric crystals, potential radiation converters for thermophotovoltaic applications. In our experiments, the (80 at.%) Er:YAG crystal was opaque between 1.45 {\\mu}m and 1.64 {\\mu}m. In this spectral range, its absorptance {\\alpha}({\\lambda}) is spectrally flat and differentiates from unity only by a small amount of reflection. The shape of the emissivity spectrum {\\epsilon}({\\lambda}) closely matches that of absorptance {\\alpha}({\\lambda}), suggesting that the Kirchhoff law can adequately describe thermal radiation of opaque bodies, even if the requirement of thermodynamic equilibrium is not satisfie...

  10. Baseline Surface Radiation Network (BSRN) quality control of solar radiation data on the Gangneung-Wonju National University radiation station

    Science.gov (United States)

    Zo, Il-Sung; Jee, Joon-Bum; Kim, Bu-Yo; Lee, Kyu-Tae

    2017-02-01

    Gangneung-Wonju National University (GWNU) radiation station has been collecting data on global, direct, and diffuse solar radiation since 2011. We conducted a quality control (QC) assessment of GWNU data collected between 2012 and 2014, using procedures outlined by the Baseline Surface Radiation Network (BSRN). The QC process involved the comparison of observations, the correction of observational equipment, the examination of physically possible limits, and the comparative testing of observations and model calculations. Furthermore, we performed a shading check of the observational environment around the GWNU solar station. For each solar radiation element (observed every minute), we performed a QC check and investigated any flagged problems. 98.31% of the data were classified as good quality, while the remaining 1.69% were flagged as bad quality based on the shading check and comparison tests. We then compared the good-quality data to the global solar radiation data observed at the Gangwon Regional Office of Meteorology (GROM). After performing this comparison, the determination coefficient (R2; 0.98) and standard deviation (SD; 0.92 MJ m-2) increased compared to those computed before the QC check (0.97 and 1.09 MJ m-2). Even considering the geographical differences and weather effects between the two stations, these results are statistically significant. However, we also confirmed that the quality of the GROM data deteriorated in relation to weather conditions because of poor maintenance. Hence, we conclude that good-quality observational data rely on the maintenance of both observational equipment and the surrounding environment under optimal conditions.

  11. A Novel Approach to Thermal Design of Solar Modules: Selective-Spectral and Radiative Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xingshu; Dubey, Rajiv; Chattopadhyay, Shashwata; Khan, Mohammad Ryyan; Chavali, Raghu Vamsi; Silverman, Timothy J.; Kottantharayil, Anil; Vasi, Juzer; Alam, Muhammad Ashraful

    2016-11-21

    For commercial solar modules, up to 80% of the incoming sunlight may be dissipated as heat, potentially raising the temperature 20-30 degrees C higher than the ambient. In the long run, extreme self-heating may erode efficiency and shorten lifetime, thereby, dramatically reducing the total energy output by almost ~10% Therefore, it is critically important to develop effective and practical cooling methods to combat PV self-heating. In this paper, we explore two fundamental sources of PV self-heating, namely, sub-bandgap absorption and imperfect thermal radiation. The analysis suggests that we redesign the optical and thermal properties of the solar module to eliminate the parasitic absorption (selective-spectral cooling) and enhance the thermal emission to the cold cosmos (radiative cooling). The proposed technique should cool the module by ~10 degrees C, to be reflected in significant long-term energy gain (~ 3% to 8% over 25 years) for PV systems under different climatic conditions.

  12. Thermal Assessment of Landsat-7 ETM+ Radiative Cooler in Instrument and Spacecraft Thermal Vacuum Tests and in Flight

    Science.gov (United States)

    Choi, Michael K.

    1999-01-01

    During the radiative cooler cool-down phase of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument thermal vacuum test #3, the coldest temperature that the Cold Focal Plane Array (CFPA) achieved was 89.5 K. The cold stage/CFPA temperature decreased from 315 K to 89.5 K in 80 hours. In the spacecraft and instrument integrated thermal vacuum test, the cold stage/CFPA temperature decreased from 315 K to 86.9 K in 80 hours, and was still decreasing at a rate of 0.08 K/hr when the cool-down was terminated. The cool-down was faster, and a colder CFPA temperature was obtained. In flight, the cooler cool- down was even faster, and colder. The cold stage/CFPA temperature decreased from 315 K to 89.7 K in 33 hours, and was still decreasing at a rate of 1 K/hr when cool- down was terminated at 89.7 K. The factors that affected the ETM+ cooler cool-down are the radiation heat sink temperature for the cold stage and intermediate stage, parasitic radiation heat load to the cooler, parasitic conduction heat load to the cooler, and cooler outgas time preceding cooler cool-down.

  13. Thermal Assessment of Landsat-7 ETM+ Radiative Cooler in Instrument and Spacecraft Thermal Vacuum Tests and in Flight

    Science.gov (United States)

    Choi, Michael K.

    1999-01-01

    During the radiative cooler cool-down phase of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument thermal vacuum test #3, the coldest temperature that the Cold Focal Plane Array (CFPA) achieved was 89.5 K. The cold stage/CFPA temperature decreased from 315 K to 89.5 K in 80 hours. In the spacecraft and instrument integrated thermal vacuum test, the cold stage/CFPA temperature decreased from 315 K to 86.9 K in 80 hours, and was still decreasing at a rate of 0.08 K/hr when the cool-down was terminated. The cool-down was faster, and a colder CFPA temperature was obtained. In flight, the cooler cool- down was even faster, and colder. The cold stage/CFPA temperature decreased from 315 K to 89.7 K in 33 hours, and was still decreasing at a rate of 1 K/hr when cool- down was terminated at 89.7 K. The factors that affected the ETM+ cooler cool-down are the radiation heat sink temperature for the cold stage and intermediate stage, parasitic radiation heat load to the cooler, parasitic conduction heat load to the cooler, and cooler outgas time preceding cooler cool-down.

  14. Grey-body surface radiation coupled with conduction and convection for general geometries

    Science.gov (United States)

    Engelman, Michael; Jamnia, Mohammad-Ali

    1991-11-01

    This paper presents a numerical technique for the simulation of the effects of grey-diffuse surface radiation on the temperature field of fluid flows using FIDAP, a general purpose incompressible, viscous fluid code. The radiating surface relationships assume a non-participating medium, constant surface temperature and heat fluxes at the discretized elemental level. The technique involves the decoupling of energy and radiation exchange equations. A concept of macrosurfaces, each containing a number of radiating boundary surfaces, is introduced. These boundary macroelements then carry the information from the radiating boundary into the fluid regime. A number of simulations illustrating the algorithm are presented.

  15. Thermal conditions on the International Space Station: Heat flux and temperature investigation of main radiators for the Alpha Magnetic Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Min, E-mail: alice.m.xie@icloud.com; Gao, Jianmin; Wu, Shaohua; Qin, Yukun

    2016-09-11

    The investigation on heat flux can clarify the thermal condition and explain temperature behavior on the main radiators of the Alpha Magnetic Spectrometer (AMS). In this paper, a detailed investigation of heat flux on the AMS main radiators is proposed. The heat transfer process of the AMS main radiators is theoretically analyzed. An updated thermal model of the AMS on the International Space Station (ISS) is developed to calculate the external heat flux density on the AMS main radiators. We conclude the ISS components and operations affect on the solar flux density of the AMS main radiators by reflecting or shading solar illumination. According to the energy conservation on the AMS main radiators, the temperature variation mainly depends on the solar flux change. The investigations are conducive to reference for the long-duration thermal control of the AMS, and knowledge for the thermal conditions on the ISS.

  16. Thermal conditions on the International Space Station: Heat flux and temperature investigation of main radiators for the Alpha Magnetic Spectrometer

    Science.gov (United States)

    Xie, Min; Gao, Jianmin; Wu, Shaohua; Qin, Yukun

    2016-09-01

    The investigation on heat flux can clarify the thermal condition and explain temperature behavior on the main radiators of the Alpha Magnetic Spectrometer (AMS). In this paper, a detailed investigation of heat flux on the AMS main radiators is proposed. The heat transfer process of the AMS main radiators is theoretically analyzed. An updated thermal model of the AMS on the International Space Station (ISS) is developed to calculate the external heat flux density on the AMS main radiators. We conclude the ISS components and operations affect on the solar flux density of the AMS main radiators by reflecting or shading solar illumination. According to the energy conservation on the AMS main radiators, the temperature variation mainly depends on the solar flux change. The investigations are conducive to reference for the long-duration thermal control of the AMS, and knowledge for the thermal conditions on the ISS.

  17. Status of the Development of Low Cost Radiator for Surface Fission Power - II

    Science.gov (United States)

    Tarau, Calin; Maxwell, Taylor; Anderson, William G.; Wagner, Corey; Wrosch, Matthew; Briggs, Maxwell H.

    2016-01-01

    NASA Glenn Research Center (GRC) is developing fission power system technology for future Lunar and Martian surface power applications. The systems are envisioned in the 10 to 100kWe range and have an anticipated design life of 8 to 15 years with no maintenance. NASA GRC is currently setting up a 55 kWe non-nuclear system ground test in thermal-vacuum to validate technologies required to transfer reactor heat, convert the heat into electricity, reject waste heat, process the electrical output, and demonstrate overall system performance. The paper reports on the development of the heat pipe radiator to reject the waste heat from the Stirling convertors. Reducing the radiator mass, size, and cost is essential to the success of the program. To meet these goals, Advanced Cooling Technologies, Inc. (ACT) and Vanguard Space Technologies, Inc. (VST) are developing a single facesheet radiator with heat pipes directly bonded to the facesheet. The facesheet material is a graphite fiber reinforced composite (GFRC) and the heat pipes are titanium/water Variable Conductance Heat Pipes (VCHPs). By directly bonding a single facesheet to the heat pipes, several heavy and expensive components can be eliminated from the traditional radiator design such as, POCO"TM" foam saddles, aluminum honeycomb, and a second facesheet. As mentioned in previous papers by the authors, the final design of the waste heat radiator is described as being modular with independent GFRC panels for each heat pipe. The present paper reports on test results for a single radiator module as well as a radiator cluster consisting of eight integral modules. These tests were carried out in both ambient and vacuum conditions. While the vacuum testing of the single radiator module was performed in the ACT's vacuum chamber, the vacuum testing of the eight heat pipe radiator cluster took place in NASA GRC's vacuum chamber to accommodate the larger size of the cluster. The results for both articles show good agreement

  18. Can radiation therapy treatment planning system accurately predict surface doses in postmastectomy radiation therapy patients?

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Sharon [National University of Singapore, Yong Loo Lin School of Medicine (Singapore); Back, Michael [Northern Sydney Cancer Centre, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Tan, Poh Wee; Lee, Khai Mun; Baggarley, Shaun [National University, Cancer Institute, Department of Radiation Oncology, National University, Hospital, Tower Block (Singapore); Lu, Jaide Jay, E-mail: mdcljj@nus.edu.sg [National University of Singapore, Yong Loo Lin School of Medicine (Singapore); National University, Cancer Institute, Department of Radiation Oncology, National University, Hospital, Tower Block (Singapore)

    2012-07-01

    Skin doses have been an important factor in the dose prescription for breast radiotherapy. Recent advances in radiotherapy treatment techniques, such as intensity-modulated radiation therapy (IMRT) and new treatment schemes such as hypofractionated breast therapy have made the precise determination of the surface dose necessary. Detailed information of the dose at various depths of the skin is also critical in designing new treatment strategies. The purpose of this work was to assess the accuracy of surface dose calculation by a clinically used treatment planning system and those measured by thermoluminescence dosimeters (TLDs) in a customized chest wall phantom. This study involved the construction of a chest wall phantom for skin dose assessment. Seven TLDs were distributed throughout each right chest wall phantom to give adequate representation of measured radiation doses. Point doses from the CMS Xio Registered-Sign treatment planning system (TPS) were calculated for each relevant TLD positions and results correlated. There were no significant difference between measured absorbed dose by TLD and calculated doses by the TPS (p > 0.05 (1-tailed). Dose accuracy of up to 2.21% was found. The deviations from the calculated absorbed doses were overall larger (3.4%) when wedges and bolus were used. 3D radiotherapy TPS is a useful and accurate tool to assess the accuracy of surface dose. Our studies have shown that radiation treatment accuracy expressed as a comparison between calculated doses (by TPS) and measured doses (by TLD dosimetry) can be accurately predicted for tangential treatment of the chest wall after mastectomy.

  19. Projections onto the Pareto surface in multicriteria radiation therapy optimization

    Energy Technology Data Exchange (ETDEWEB)

    Bokrantz, Rasmus, E-mail: bokrantz@kth.se, E-mail: rasmus.bokrantz@raysearchlabs.com [Optimization and Systems Theory, Department of Mathematics, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden and RaySearch Laboratories, Sveavägen 44, Stockholm SE-103 65 (Sweden); Miettinen, Kaisa [Optimization and Systems Theory, Department of Mathematics, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden and University of Jyvaskyla, Department of Mathematical Information Technology, FI-400 14 University of Jyvaskyla (Finland)

    2015-10-15

    Purpose: To eliminate or reduce the error to Pareto optimality that arises in Pareto surface navigation when the Pareto surface is approximated by a small number of plans. Methods: The authors propose to project the navigated plan onto the Pareto surface as a postprocessing step to the navigation. The projection attempts to find a Pareto optimal plan that is at least as good as or better than the initial navigated plan with respect to all objective functions. An augmented form of projection is also suggested where dose–volume histogram constraints are used to prevent that the projection causes a violation of some clinical goal. The projections were evaluated with respect to planning for intensity modulated radiation therapy delivered by step-and-shoot and sliding window and spot-scanned intensity modulated proton therapy. Retrospective plans were generated for a prostate and a head and neck case. Results: The projections led to improved dose conformity and better sparing of organs at risk (OARs) for all three delivery techniques and both patient cases. The mean dose to OARs decreased by 3.1 Gy on average for the unconstrained form of the projection and by 2.0 Gy on average when dose–volume histogram constraints were used. No consistent improvements in target homogeneity were observed. Conclusions: There are situations when Pareto navigation leaves room for improvement in OAR sparing and dose conformity, for example, if the approximation of the Pareto surface is coarse or the problem formulation has too permissive constraints. A projection onto the Pareto surface can identify an inaccurate Pareto surface representation and, if necessary, improve the quality of the navigated plan.

  20. Thermal Diodes Based on Near-Field Radiation

    Science.gov (United States)

    2015-10-01

    rectifiers and switches. 21 Approved for public release; distribution unlimited. 1. E. Rousseau , A. Siria, G. Jourdan, S. Volz, F. Comin, J. Chevrier...4. A. Narayanaswamy and G. Chen, "Surface modes for near field thermophotovoltaics," Applied Physics Letters 82, 3544-3546 (2003). 5. E. Rousseau , A...Lett. 2008, 93 (4), 043109. (7) Rousseau , E.; Siria, A.; Jourdan, G.; Volz, S.; Comin, F.; Chevrier, J.; Greffet, J.-J. Nat. Photon. 2009, 3 (9

  1. A Near-Infrared and Thermal Imager for Mapping Titan's Surface Features

    Science.gov (United States)

    Aslam, S.; Hewagma, T.; Jennings, D. E.; Nixon, C.

    2012-01-01

    Approximately 10% of the solar insolation reaches the surface of Titan through atmospheric spectral windows. We will discuss a filter based imaging system for a future Titan orbiter that will exploit these windows mapping surface features, cloud regions, polar storms. In the near-infrared (NIR), two filters (1.28 micrometer and 1.6 micrometer), strategically positioned between CH1 absorption bands, and InSb linear array pixels will explore the solar reflected radiation. We propose to map the mid, infrared (MIR) region with two filters: 9.76 micrometer and 5.88-to-6.06 micrometers with MCT linear arrays. The first will map MIR thermal emission variations due to surface albedo differences in the atmospheric window between gas phase CH3D and C2H4 opacity sources. The latter spans the crossover spectral region where observed radiation transitions from being dominated by thermal emission to solar reflected light component. The passively cooled linear arrays will be incorporated into the focal plane of a light-weight thin film stretched membrane 10 cm telescope. A rad-hard ASIC together with an FPGA will be used for detector pixel readout and detector linear array selection depending on if the field-of-view (FOV) is looking at the day- or night-side of Titan. The instantaneous FOV corresponds to 3.1, 15.6, and 31.2 mrad for the 1, 5, and 10 micrometer channels, respectively. For a 1500 km orbit, a 5 micrometer channel pixel represents a spatial resolution of 91 m, with a FOV that spans 23 kilometers, and Titan is mapped in a push-broom manner as determined by the orbital path. The system mass and power requirements are estimated to be 6 kg and 5 W, respectively. The package is proposed for a polar orbiter with a lifetime matching two Saturn seasons.

  2. Radiation Environment and Surface Radiolytic Interactions at Mimas

    Science.gov (United States)

    Cooper, J. F.; Sittler, E. C.; Lipatov, A. S.; Sturner, S. J.; Paranicas, C.; Cooper, P. D.

    2010-01-01

    thermal conductivity of the ice, potentially contributing to reported thermal anomalies from Cassini infrared map observations. Low amplitude of trailing-leading asymmetry in optical albedo and color maps at Mimas is suggestive of relative weakness of asymmetrical effects from low-energy ions. Greater induced asymmetries are expected and observed for the moons beyond Enceladus in the middle magnetospheric region of hot plasma ions at much greater fluxes than at Mimas. Low density (1.15 g/cc) of this moon indicates paucity of mineral salts and radiogenic heating to maintain subsurface liquids, so Enceladus-like cryovolcanism as a resurfacing process is unlikely despite closer proximity to Saturn, greater tidal forcing, and more intense surface irradiation than for Enceladus.

  3. High Thermal Conductivity Polymer Matrix Composites (PMC) for Advanced Space Radiators

    Science.gov (United States)

    Shin, E. Eugene; Bowman, Cheryl; Beach, Duane

    2007-01-01

    High temperature polymer matrix composites (PMC) reinforced with high thermal conductivity (approx. 1000 W/mK) pitch-based carbon fibers are evaluated for a facesheet/fin structure of large space radiator systems. Significant weight reductions along with improved thermal performance, structural integrity and space durability toward its metallic counterparts were envisioned. Candidate commercial resin systems including Cyanate Esters, BMIs, and polyimide were selected based on thermal capabilities and processability. PMC laminates were designed to match the thermal expansion coefficient of various metal heat pipes or tubes. Large, but thin composite panels were successfully fabricated after optimizing cure conditions. Space durability of PMC with potential degradation mechanisms was assessed by simulated thermal aging tests in high vacuum, 1-3 x 10(exp -6) torr, at three temperatures, 227 C, 277 C, and 316 C for up to one year. Nanocomposites with vapor-grown carbon nano-fibers and exfoliated graphite flakes were attempted to improve thermal conductivity (TC) and microcracking resistance. Good quality nanocomposites were fabricated and evaluated for TC and durability including radiation resistance. TC was measured in both in-plan and thru-the-thickness directions, and the effects of microcracks on TC are also being evaluated. This paper will discuss the systematic experimental approaches, various performance-durability evaluations, and current subcomponent design and fabrication/manufacturing efforts.

  4. A short history of nomograms and tables used for thermal radiation calculations

    Science.gov (United States)

    Stewart, Seán. M.; Johnson, R. Barry

    2016-09-01

    The theoretical concept of a perfect thermal radiator, the blackbody, was first introduced by the German physicist Gustav Robert Kirchhoff in 1860. By the latter half of the nineteenth century it had become the object of intense theoretical and experimental investigation. While an attempt at trying to theoretically understand the behavior of radiation emitted from a blackbody was undertaken by many eminent physicists of the day, its solution was not found until 1900 when Max Planck put forward his now famous law for thermal radiation. Today, of course, understanding blackbody behavior is vitally important to many fields including infrared systems, illumination, pyrometry, spectroscopy, astronomy, thermal engineering, cryogenics, and meteorology. Mathematically, the form Planck's law takes is rather cumbersome meaning calculations made with it before the advent of modern computers were rather tedious, dramatically slowing the process of computation. Fortunately, during those early days of the twentieth century researchers quickly realized Planck's equation, and the various functions closely related to it, readily lend themselves to being given a graphical, mechanical, or numerically tabulated form for their evaluation. The first of these computational aids to appear were tables. These arose shortly after Planck introduced his equation, were produced in the greatest number, and remained unsurpassed in their level of accuracy compared to all other aids made. It was also not long before nomograms designed to aid thermal radiation calculations appeared. Essentially a printed chart and requiring nothing more than a straightedge to use, nomograms were cheap and extremely easy to use. Facilitating instant answers to a range of quantities relating to thermal radiation, a number were produced and the inventiveness displayed in some was quite remarkable. In this paper we consider the historical development of many of the nomograms and tables developed and used by generations

  5. Quantitative reconstruction of thermal and dynamic characteristics of lava flow from surface thermal measurements

    Science.gov (United States)

    Korotkii, Alexander; Kovtunov, Dmitry; Ismail-Zadeh, Alik; Tsepelev, Igor; Melnik, Oleg

    2016-06-01

    We study a model of lava flow to determine its thermal and dynamic characteristics from thermal measurements of the lava at its surface. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. We develop a numerical approach to the mathematical problem in the case of steady-state flow. Assuming that the temperature and the heat flow are prescribed at the upper surface of the model domain, we determine the flow characteristics in the entire model domain using a variational (adjoint) method. We have performed computations of model examples and showed that in the case of smooth input data the lava temperature and the flow velocity can be reconstructed with a high accuracy. As expected, a noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. Also we analyse the influence of optimization methods on the solution convergence rate. The proposed method for reconstruction of physical parameters of lava flows can also be applied to other problems in geophysical fluid flows.

  6. Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind

    Science.gov (United States)

    de la Cita, V. M.; Bosch-Ramon, V.; Paredes-Fortuny, X.; Khangulyan, D.; Perucho, M.

    2017-02-01

    Context. Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters owing to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal emission. Aims: We study numerically the impact of the presence of inhomogeneities or clumps in the stellar wind on the high-energy non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. Methods: We compute the trajectories and physical properties of the streamlines in the shocked pulsar wind without clumps, with a small clump, and with a large clump. This information is used to characterize the injection and the steady state distribution of non-thermal particles accelerated at shocks formed in the pulsar wind. The synchrotron and inverse Compton emission from these non-thermal particles is calculated, accounting also for the effect of gamma-ray absorption through pair creation. A specific study is done for PSR B1259-63/LS2883. Results: When stellar wind clumps perturb the two-wind interaction region, the associated non-thermal radiation in the X-ray band, of synchrotron origin, and in the GeV-TeV band, of inverse Compton origin, is affected by several equally important effects: (i) strong changes in the plasma velocity direction that result in Doppler boosting factor variations; (ii) strengthening of the magnetic field that mainly enhances the synchrotron radiation; (iii) strengthening of the pulsar wind kinetic energy dissipation at the shock, potentially available for particle acceleration; and (iv) changes in the rate of adiabatic losses that affect the lower energy part of the non-thermal particle population. The radiation above 100 GeV detected, presumably, during the post-periastron crossing of the Be star disc in PSR B1259-63/LS2883, can be roughly reproduced assuming that the crossing of the disc is modelled as the encounter with a large inhomogeneity. Conclusions

  7. Molecular cloud formation via thermal instability of finite resistive viscous radiating plasma with finite Larmor radius corrections

    Science.gov (United States)

    Kaothekar, Sachin

    2017-06-01

    The effect of radiative heat-loss function and finite ion Larmor radius (FLR) corrections on the thermal instability of infinite homogeneous viscous plasma has been investigated incorporating the effects of thermal conductivity and finite electrical resistivity for the formation of a molecular cloud. The general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. Furthermore the wave propagation along and perpendicular to the direction of external magnetic field has been discussed. Stability of the medium is discussed by applying Routh Hurwitz's criterion and it is found that thermal instability criterion determines the stability of the medium. We find that the presence of radiative heat-loss function and thermal conductivity modify the fundamental criterion of thermal instability into radiatively driven thermal instability criterion. In longitudinal direction FLR corrections, viscosity, magnetic field and finite resistivity have no effect on thermal instability criterion. The presence of radiative heat-loss function and thermal conductivity modify the fundamental thermal instability criterion into radiatively driven thermal instability criterion. Also the FLR corrections modify the growth rate of the Alfven mode. For transverse wave propagation FLR corrections, radiative heat-loss function, magnetic field and thermal conductivity modify the thermal instability criterion. From the curves it is clear that heat-loss function, FLR corrections and viscosity have stabilizing effect, while finite resistivity has destabilizing effect on the thermal modes. Our results show that the FLR corrections and radiative heat-loss functions affect the evolution of interstellar molecular clouds and star formation.

  8. Effects of ultraviolet and protons radiations on thermal control coatings after contamination

    Science.gov (United States)

    Faye, D.; Marco, J.

    2003-09-01

    The impact of molecular deposits from spacecraft materials outgassing is not only dependent on sensitive surface nature and contaminant type but also on space environment parameters. In order to study the combined effects of contamination and solar radiation, ground tests have been performed on thermal control coatings: innovative ones such as Flexible and Rigid Solar Reflectors (FSR and RSR), and classic ones such as Optical Solar Reflectors (OSR) and Second Surface Mirrors (SSM). During a first phase, samples of these cold coatings have been exposed to an outgassing flux of different widely used materials: - a PU1 black paint, - a conformal coating MAPSIL 213B, - a structural adhesive Scotchweld EC2216 and to an outgassing flux coming from the mixture of these three materials. During a second phase, the samples have been exposed through two successive tests (either under UV or protons) to a simulated space environment corresponding to one year satellite GEO orbit on North / South faces. Material degradation has been evaluated by in-situ reflectance spectra in the range 250-2500 nm (UV test) and in the range 250-840 nm (Protons test). Negligible changes occurred during initial air to vacuum transition whereas significant recoveries of degradations occurred when returning to ambient atmospheric pressure. The observed degradation is the most important in the UV-visible range independently of the contaminants and substrates. It is partly due to contaminants and substrates for silicone cold coatings FSRs, RSRs, mainly due to contaminants for OSRs, SSMs and mainly due to substrates in the case of paints.

  9. Developments in modelling of thermal radiation from pool and jet fires

    NARCIS (Netherlands)

    Boot, H.

    2016-01-01

    In the past decades, the standard approach in the modelling of consequences of pool and jet fires would be to describe these fires as tilted cylindrical shaped radiating flame surfaces, having a specific SEP (Surface Emissive Power). Some fine tuning on pool fires has been done by Rew and Hulbert in

  10. Thermal neutron imaging through XRQA2 GAFCHROMIC films coupled with a cadmium radiator

    Energy Technology Data Exchange (ETDEWEB)

    Sacco, D. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); INAIL – DIT, Via di Fontana Candida n.1, 00040 Monteporzio Catone (Italy); Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); Bortot, D. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria16, 20133 Milano (Italy); Palomba, M. [ENEA Casaccia, Via Anguillarese, 301, S. Maria di Galeria, 00123 Roma (Italy); Pola, A. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria16, 20133 Milano (Italy); Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); Gentile, A. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); Strigari, L. [Laboratory of Medical Physics, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144 Roma (Italy); Pressello, C. [Department of Medical Physics, Azienda Ospedaliera San Camillo Forlanini, Circonvallazione Gianicolense 87, 00152 Roma (Italy); Soriani, A. [Laboratory of Medical Physics, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144 Roma (Italy); Gómez-Ros, J.M. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain)

    2015-10-21

    A simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 10{sup 9}–10{sup 10} cm{sup −2}, using the ex-core radial thermal neutron column of the ENEA Casaccia – TRIGA reactor. The results are presented in this work.

  11. Thermal neutron imaging through XRQA2 GAFCHROMIC films coupled with a cadmium radiator

    Science.gov (United States)

    Sacco, D.; Bedogni, R.; Bortot, D.; Palomba, M.; Pola, A.; Introini, M. V.; Lorenzoli, M.; Gentile, A.; Strigari, L.; Pressello, C.; Soriani, A.; Gómez-Ros, J. M.

    2015-10-01

    A simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 109-1010 cm-2, using the ex-core radial thermal neutron column of the ENEA Casaccia - TRIGA reactor. The results are presented in this work.

  12. Experimental investigation of transient thermal behavior of an airship under different solar radiation and airflow conditions

    Science.gov (United States)

    Li, De-Fu; Xia, Xin-Lin; Sun, Chuang

    2014-03-01

    Knowledge of the thermal behavior of airships is crucial to the development of airship technology. An experiment apparatus is constructed to investigate the thermal response characteristics of airships, and the transient temperature distributions of both hull and inner gas are obtained under the irradiation of a solar simulator and various airflow conditions. In the course of the research, the transient temperature change of the experimental airship is measured for four airflow speeds of 0 m/s (natural convection), 3.26 m/s, 5.5 m/s and 7.0 m/s, and two incident solar radiation values of 842.4 W/m2 and 972.0 W/m2. The results show that solar irradiation has significant influence on the airship hull and inner gas temperatures even if the airship stays in a ground airflow environment where the heat transfer is dominated by radiation and convection. The airflow around the airship is conducive to reduce the hull temperature and temperature nonuniformity. Transient thermal response of airships rapidly varies with time under solar radiation conditions and the hull temperature remains approximately constant in ˜5-10 min. Finally, a transient thermal model of airship is developed and the model is validated through comparison with the experimental data.

  13. Electromagnetohydrodynamic flow of blood and heat transfer in a capillary with thermal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, A. [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Shit, G.C., E-mail: gopal_iitkgp@yahoo.co.in [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Institute of Mathematical Sciences, Chennai 600113 (India)

    2015-03-15

    This paper presents a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall. The effect of thermal radiation and velocity slip condition have been taken into account. A rigorous mathematical model for describing Joule heating in electro-osmotic flow of blood including the Poisson–Boltzmann equation, the momentum equation and the energy equation is developed. The alterations in the thermal transport phenomenon, induced by the variation of imposed electromagnetic effects, are thoroughly explained through an elegant mathematical formalism. Results presented here pertain to the case where the height of the capillary is much greater than the thickness of electrical double layer comprising the stern and diffuse layers. The essential features of the electromagnetohydrodynamic flow of blood and associated heat transfer characteristics through capillary are clearly highlighted by the variations in the non-dimensional parameters for velocity profile, temperature profile and the Nusselt number. The study reveals that the temperature of blood can be controlled by regulating Joule heating parameter. - Highlights: • Electromagnetohydrodynamic flow of blood in capillary is studied. • Potential electric field is applied for driving elecroosmotic flow of blood. • Effect of thermal radiation, Joule heating and velocity slip is investigated. • Thermal radiation bears the significant change in the temperature field.

  14. Effect of Ionizing Beta Radiation on the Mechanical Properties of Poly(ethylene under Thermal Stress

    Directory of Open Access Journals (Sweden)

    Bednarik Martin

    2016-01-01

    Full Text Available It was found in this study, that ionizing beta radiation has a positive effect on the mechanical properties of poly(ethylene. In recent years, there have been increasing requirements for quality and cost effectiveness of manufactured products in all areas of industrial production. These requirements are best met with the polymeric materials, which have many advantages in comparison to traditional materials. The main advantages of polymer materials are especially in their ease of processability, availability, and price of the raw materials. Radiation crosslinking is one of the ways to give the conventional plastics mechanical, thermal, and chemical properties of expensive and highly resistant construction polymers. Several types of ionizing radiation are used for crosslinking of polymers. Each of them has special characteristics. Electron beta and photon gamma radiation are used the most frequently. The great advantage is that the crosslinking occurs after the manufacturing process at normal temperature and pressure. The main purpose of this paper has been to determine the effect of ionizing beta radiation on the tensile modulus, strength and elongation of low and high density polyethylene (LDPE and HDPE. These properties were examined in dependence on the dosage of the ionizing beta radiation (non-irradiated samples and those irradiated by dosage 99 kGy were compared and on the test temperature. Radiation cross-linking of LDPE and HDPE results in increased tensile strength and modulus, and decreased of elongation. The measured results indicate that ionizing beta radiation treatment is effective tool for improvement of mechanical properties of LDPE and HDPE under thermal stress.

  15. Magnetohydrodynamic flow of Carreau fluid over a convectively heated surface in the presence of non-linear radiation

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Masood [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Hashim, E-mail: hashim_alik@yahoo.com [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Hussain, M. [Department of Sciences and Humanities, National University of Computer and Emerging Sciences, Islamabad 44000 (Pakistan); Azam, M. [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan)

    2016-08-15

    This paper presents a study of the magnetohydrodynamic (MHD) boundary layer flow of a non-Newtonian Carreau fluid over a convectively heated surface. The analysis of heat transfer is further performed in the presence of non-linear thermal radiation. The appropriate transformations are employed to bring the governing equations into dimensionless form. The numerical solutions of the partially coupled non-linear ordinary differential equations are obtained by using the Runge-Kutta Fehlberg integration scheme. The influence of non-dimensional governing parameters on the velocity, temperature, local skin friction coefficient and local Nusselt number is studied and discussed with the help of graphs and tables. Results proved that there is significant decrease in the velocity and the corresponding momentum boundary layer thickness with the growth in the magnetic parameter. However, a quite the opposite is true for the temperature and the corresponding thermal boundary layer thickness. - Highlights: • We investigated the Magnetohydrodynamic flow of Carreau constitutive fluid model. • Impact of non-linear thermal radiation is further taken into account. • Runge-Kutta Fehlberg method is employed to obtain the numerical solutions. • Fluid velocity is higher in case of hydromagnetic flow in comparison with hydrodynamic flow. • The local Nusselt number is a decreasing function of the thermal radiation parameter.

  16. Land surface thermal characterization of Asian-pacific region with Japanese geostationary satellite

    Science.gov (United States)

    Oyoshi, K.; Tamura, M.

    2010-12-01

    Land Surface Temperature (LST) is a significant indicator of energy balance at the Earth's surface. It is required for a wide variety of climate, hydrological, ecological, and biogeochemical studies. Although LST is highly variable both temporally and spatially, it is impossible for polar-orbiting satellite to detect hourly changes in LST, because the satellite is able to only collect data of the same area at most twice a day. On the other hand, geostationary satellite is able to collect hourly data and has a possibility to monitor hourly changes in LST, therefore hourly measurements of geostationary satellite enables us to characterize detailed thermal conditions of the Earth's surface and improve our understanding of the surface energy balance. Multi-functional Transport Satellite (MTSAT) is a Japanese geostationary satellite launched in 2005 and covers Asia-Pacific region. MTSAT provides hourly data with 5 bands including two thermal infrared (TIR) bands in the 10.5-12.5 micron region. In this research, we have developed a methodology to retrieve hourly LST from thermal infrared data of MTSAT. We applied Generalized Split-window (GSW) equation to estimate LST from TIR data. First, the brightness temperatures measured at sensor on MTSAT was simulated by radiative transfer code (MODTRAN), and the numerical coefficients of GSW equation were optimized based on the simulation results with non-linear minimization algorithm. The standard deviation of derived GSW equation was less than or equal to 1.09K in the case of viewing zenith angle lower than 40 degree and 1.73K in 60 degree. Then, spatial distributions of LST have been mapped optimized GSW equation with brightness temperatures of MTSAT IR1 and IR2 and emissivity map from MODIS product. Finally, these maps were validated with MODIS LST product (MOD11A1) over four Asian-pacific regions such as Bangkok, Tokyo, UlanBator and Jakarta , It is found that RMSE of these regions were 4.57K, 2.22K, 2.71K and 3.92K

  17. Effect of surface modification of Grewia optiva fibres on their physicochemical and thermal properties

    Indian Academy of Sciences (India)

    Amar S Singha; Ashvinder K Rana

    2012-12-01

    This paper deals with the surface modification of Grewia optiva fibre through benzoylation and graft copolymerization process. Benzoylation of Grewia optiva fibre has been carried out on mercerized fibre with varying concentrations of benzoyl chloride solution. Graft copolymerization of acrylonitrile (AN) onto Grewia optiva fibre was carried out with ceric ammonium nitrate as the redox initiator in aqueous medium under the influence of microwave radiation. Raw, graft copolymerized and benzoylated fibres were subjected to evaluation of some of their properties like swelling behaviour, moisture absorbance and chemical resistance behaviour. It has been observed that 5% benzoyl chloride treated and graft copolymerized Grewia optiva show more resistance towards moisture, water and chemicals when compared with that of raw fibre. Further morphological, structural changes, thermal stability and crystallinity of raw, graft copolymerized, pretreated and benzoylated fibres have also been studied by SEM, FTIR, TGA and XRD techniques.

  18. Thermal instability (or not?) in three-dimensional, global, radiative GRMHD simulations of geometrically thin discs

    CERN Document Server

    Mishra, B; Johnson, L C; Kluźniak, W

    2016-01-01

    We present results of a set of three-dimensional, general relativistic radiation magnetohydro- dynamics simulations of thin accretion discs to test their thermal stability. We consider two cases, one that is initially radiation-pressure dominated and expected to be thermally unstable and another that is initially gas-pressure dominated and expected to remain stable. Indeed, we find that cooling dominates over heating in the radiation-pressure-dominated case, causing the disc to collapse vertically on the local cooling timescale. On the other hand, the gas-pressure- dominated case, which was run for twice as long as the radiation-pressure-dominated case, remains stable, with heating and cooling roughly in balance. Because the radiation-pressure- dominated disc collapses to the point that we are no longer able to resolve it, we had to terminate the simulation. Thus, we do not know for sure whether it might find a much thinner, stable solution or if it will make a transition to unstable expansion and exhibit lim...

  19. Thermal and radiative characteristics of oxyfluoride glass singly doped with lanthanide ions

    Institute of Scientific and Technical Information of China (English)

    Barbara; Gra(z)yna; DOMINIAK-DZIK; RYBA-ROMANOWSKI

    2010-01-01

    Rare earths-doped oxyfluoride glasses based on germanium oxide and lead fluoride were prepared from commercial raw materials.The glasses with general composition of 50GeO2-(50-x-y)PbO-yPbF2-xLnF3(Ln=Pr3+-Yb3+),contained different concentrations of optically active dopants(x=0.2 mol.% and 2 mol.%)and PbF2(y≤15 mol.%).The differential thermal analysis(DTA)was used to determine both thermal characteristic and thermal stability properties of the glasses in the function of the kind of dopant,its concentration,and a glass composition.Characteristic glass temperatures such as glass transition temperature(Tg),glass crystallization temperature(Tc)and temperature corresponding to the maximum of the crystallization rate(Tpc)were evaluated.On the basis of obtained results,the thermal stabilities of glasses under study were evaluated using various thermal stability criteria(Dietzel factor △T,Saad-Poulain factors H' and S').It was found that the increase in rare earth fluoride contents influenced thermal characteristics when the characteristic temperatures of the individual glass was shifted towards higher values.The effect of the PbF2 content and the kind of rare earth impurity on the glass stability was observed.Absorption spectra of lanthanide-doped glasses were measured at room temperature and used to determine the phenomenological intensity parameters Ωt and next,to estimate radiative properties of lanthanide ions in this matrix.Radiative transition probabilities of luminescent states of Ln3+,branching ratios and radiative lifetimes were determined.The variation of the Ωt along the lanthanide series was presented and discussed.

  20. Restoration and Reexamination of Data from the Apollo 11, 12, 14, and 15 Dust, Thermal and Radiation Engineering Measurements Experiments

    Science.gov (United States)

    McBride, Marie J.; Williams, David R.; Kent, H.; Turner, Niescja

    2012-01-01

    As part of an effort by the Lunar Data Node (LDN) we are restoring data returned by the Apollo Dust, Thermal, and Radiation Engineering Measurements (DTREM) packages emplaced on the lunar surface by the crews of Apollo 11, 12, 14, and 15. Also commonly known as the Dust Detector experiments, the DTREM packages measured the outputs of exposed solar cells and thermistors over time. They operated on the surface for up to nearly 8 years, returning data every 54 seconds. The Apollo 11 DTREM was part of the Early Apollo Surface Experiments Package (EASEP), and operated for a few months as planned following emplacement in July 1969. The Apollo 12, 14, and 15 DTREMs were mounted on the central station as part of the Apollo Lunar Surface Experiments Package (ALSEP) and operated from deployment until ALSEP shutdown in September 1977. The objective of the DTREM experiments was to determine the effects of lunar and meteoric dust, thermal stresses, and radiation exposure on solar cells. The LDN, part of the Geosciences Node of the Planetary Data System (PDS), operates out of the National Space Science Data Center (NSSDC) at Goddard Space Flight Center. The goal of the LDN is to extract lunar data stored on older media and/or in obsolete formats, restore the data into a usable digital format, and archive the data with PDS and NSSDC. For the DTREM data we plan to recover the raw telemetry, translate the raw counts into appropriate output units, and then apply calibrations. The final archived data will include the raw, translated, and calibrated data and the associated conversion tables produced from the microfilm, as well as ancillary supporting data (metadata) packaged in PDS format.

  1. Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind

    CERN Document Server

    de la Cita, Víctor M; Paredes-Fortuny, Xavier; Khangulyan, Dmitry; Perucho, Manel

    2016-01-01

    Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters due to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal emission. We study numerically the impact of the presence of inhomogeneities or clumps in the stellar wind on the high-energy non-thermal radiation of high-mass binaries hosting a non-accreting pulsar. We compute the trajectories and physical properties of the streamlines in the shocked pulsar wind without clumps, with a small clump, and with a large one. This information is used to compute the synchrotron and inverse Compton emission from the non-thermal populations, accounting also for the effect of gamma-ray absorption through pair creation. A specific study is done for PSR B1259-63/LS2883. When stellar wind clumps perturb the two-wind interaction region, the associated non-thermal radiation in the X-ray band,of synchrotron origin, and in the GeV-TeV ba...

  2. Prediction of soot and thermal radiation in a model gas turbine combustor burning kerosene fuel spray at different swirl levels

    Science.gov (United States)

    Ghose, Prakash; Patra, Jitendra; Datta, Amitava; Mukhopadhyay, Achintya

    2016-05-01

    Combustion of kerosene fuel spray has been numerically simulated in a laboratory scale combustor geometry to predict soot and the effects of thermal radiation at different swirl levels of primary air flow. The two-phase motion in the combustor is simulated using an Eulerian-Lagragian formulation considering the stochastic separated flow model. The Favre-averaged governing equations are solved for the gas phase with the turbulent quantities simulated by realisable k-ɛ model. The injection of the fuel is considered through a pressure swirl atomiser and the combustion is simulated by a laminar flamelet model with detailed kinetics of kerosene combustion. Soot formation in the flame is predicted using an empirical model with the model parameters adjusted for kerosene fuel. Contributions of gas phase and soot towards thermal radiation have been considered to predict the incident heat flux on the combustor wall and fuel injector. Swirl in the primary flow significantly influences the flow and flame structures in the combustor. The stronger recirculation at high swirl draws more air into the flame region, reduces the flame length and peak flame temperature and also brings the soot laden zone closer to the inlet plane. As a result, the radiative heat flux on the peripheral wall decreases at high swirl and also shifts closer to the inlet plane. However, increased swirl increases the combustor wall temperature due to radial spreading of the flame. The high incident radiative heat flux and the high surface temperature make the fuel injector a critical item in the combustor. The injector peak temperature increases with the increase in swirl flow mainly because the flame is located closer to the inlet plane. On the other hand, a more uniform temperature distribution in the exhaust gas can be attained at the combustor exit at high swirl condition.

  3. Earth's thermal radiation sensors for attitude determination systems of small satellites

    Science.gov (United States)

    Vertat, I.; Linhart, R.; Masopust, J.; Vobornik, A.; Dudacek, L.

    2017-07-01

    Satellite attitude determination is a complex process with expensive hardware and software and it could consume the most of resources (volume, mass, electric power), especially of small satellites as CubeSats. Thermal radiation infrared detectors could be one of useful sensors for attitude determination systems in such small satellites. Nowadays, these sensors are widely used in contact-less thermometers and thermo-cameras resulting in a low-cost technology. On low Earth orbits the infrared thermal sensors can be utilized for coarse attitude determination against a relative warm and close Earth's globe.

  4. Effects of Radiation and Long-Term Thermal Cycling on EPC 1001 Gallium Nitride Transistors

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These include radiation, extreme temperatures, and thermal cycling, to name a few. Data obtained on long-term thermal cycling of new un-irradiated and irradiated samples of EPC1001 gallium nitride enhancement-mode transistors are presented. This work was done by a collaborative effort including GRC, GSFC, and support the NASA www.nasa.gov 1 JPL in of Electronic Parts and Packaging (NEPP) Program

  5. Electrochromic Radiator Coupon Level Testing and Full Scale Thermal Math Modeling for Use on Altair Lunar Lander

    Science.gov (United States)

    Bannon, Erika T.; Bower, Chad E.; Sheth, Rubik; Stephan, Ryan

    2010-01-01

    In order to control system and component temperatures, many spacecraft thermal control systems use a radiator coupled with a pumped fluid loop to reject waste heat from the vehicle. Since heat loads and radiation environments can vary considerably according to mission phase, the thermal control system must be able to vary the heat rejection. The ability to "turn down" the heat rejected from the thermal control system is critically important when designing the system. Electrochromic technology as a radiator coating is being investigated to vary the amount of heat rejected by a radiator. Coupon level tests were performed to test the feasibility of this technology. Furthermore, thermal math models were developed to better understand the turndown ratios required by full scale radiator architectures to handle the various operation scenarios encountered during a mission profile for the Altair Lunar Lander. This paper summarizes results from coupon level tests as well as the thermal math models developed to investigate how electrochromics can be used to increase turn down ratios for a radiator. Data from the various design concepts of radiators and their architectures are outlined. Recommendations are made on which electrochromic radiator concept should be carried further for future thermal vacuum testing.

  6. Attenuating the surface Urban Heat Island within the Local Thermal Zones through land surface modification.

    Science.gov (United States)

    Wang, Jiong; Ouyang, Wanlu

    2017-02-01

    Inefficient mitigation of excessive heat is attributed to the discrepancy between the scope of climate research and conventional planning practice. This study approaches this problem at both domains. Generally, the study, on one hand, claims that the climate research of the temperature phenomenon should be at local scale, where implementation of planning and design strategies can be more feasible. On the other hand, the study suggests that the land surface factors should be organized into zones or patches, which conforms to the urban planning and design manner. Thus in each zone, the land surface composition of those excessively hot places can be compared to the zonal standard. The comparison gives guidance to the modification of the land surface factors at the target places. Specifically, this study concerns the Land Surface Temperature (LST) in Wuhan, China. The land surface is classified into Local Thermal Zones (LTZ). The specifications of temperature sensitive land surface factors are relative homogeneous in each zone and so is the variation of the LST. By extending the city scale analysis of Urban Heat Island into local scale, the Local Surface Urban Heat Islands (LSUHIs) are extracted. Those places in each zone that constantly maintain as LSUHI and exceed the homogenous LST variation are considered as target places or hotspots with higher mitigation or adaptation priority. The operation is equivalent to attenuate the abnormal LST variation in each zone. The framework is practical in the form of prioritization and zoning, and mitigation strategies are essentially operated locally.

  7. Thermal expansion compensator having an elastic conductive element bonded to two facing surfaces

    Science.gov (United States)

    Determan, William (Inventor); Matejczyk, Daniel Edward (Inventor)

    2012-01-01

    A thermal expansion compensator is provided and includes a first electrode structure having a first surface, a second electrode structure having a second surface facing the first surface and an elastic element bonded to the first and second surfaces and including a conductive element by which the first and second electrode structures electrically and/or thermally communicate, the conductive element having a length that is not substantially longer than a distance between the first and second surfaces.

  8. A short review of radiation-induced raft-mediated graft copolymerization: A powerful combination for modifying the surface properties of polymers in a controlled manner

    Science.gov (United States)

    Barsbay, Murat; Güven, Olgun

    2009-12-01

    Surface grafting of polymeric materials is attracting increasing attention as it enables the preparation of new materials from known and commercially available polymers having desirable bulk properties such as thermal stability, elasticity, permeability, etc., in conjunction with advantageous newly tailored surface properties such as biocompatibility, biomimicry, adhesion, etc. Ionizing radiation, particularly γ radiation is one of the most powerful tools for preparing graft copolymers as it generates radicals on most substrates. With the advent of living free-radical polymerization techniques, application of γ radiation has been extended to a new era of grafting; grafting in a controlled manner to achieve surfaces with tailored and well-defined properties. This report presents the current use of γ radiation in living free-radical polymerization and highlights the use of both techniques together as a combination to present an advance in the ability to prepare surfaces with desired, tunable and well-defined properties.

  9. A short review of radiation-induced raft-mediated graft copolymerization: A powerful combination for modifying the surface properties of polymers in a controlled manner

    Energy Technology Data Exchange (ETDEWEB)

    Barsbay, Murat [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey)], E-mail: mbarsbay@hacettepe.edu.tr; Gueven, Olgun [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey)], E-mail: guven@hacettepe.edu.tr

    2009-12-15

    Surface grafting of polymeric materials is attracting increasing attention as it enables the preparation of new materials from known and commercially available polymers having desirable bulk properties such as thermal stability, elasticity, permeability, etc., in conjunction with advantageous newly tailored surface properties such as biocompatibility, biomimicry, adhesion, etc. Ionizing radiation, particularly {gamma} radiation is one of the most powerful tools for preparing graft copolymers as it generates radicals on most substrates. With the advent of living free-radical polymerization techniques, application of {gamma} radiation has been extended to a new era of grafting; grafting in a controlled manner to achieve surfaces with tailored and well-defined properties. This report presents the current use of {gamma} radiation in living free-radical polymerization and highlights the use of both techniques together as a combination to present an advance in the ability to prepare surfaces with desired, tunable and well-defined properties.

  10. The Effect of Simulated Lunar Dust on the Absorptivity, Emissivity, and Operating Temperature on AZ-93 and Ag/FEP Thermal Control Surfaces

    Science.gov (United States)

    Gaier, James R.; Siamidis, John; Panko, Scott R.; Rogers, Kerry J.; Larkin, Elizabeth M. G.

    2008-01-01

    JSC-1AF lunar simulant has been applied to AZ-93 and AgFEP thermal control surfaces on aluminum or composite substrates in a simulated lunar environment. The temperature of these surfaces was monitored as they were heated with a solar simulator and cooled in a 30 K coldbox. Thermal modeling was used to determine the absorptivity ( ) and emissivity ( ) of the thermal control surfaces in both their clean and dusted states. Then, a known amount of power was applied to the samples while in the coldbox and the steady state temperatures measured. It was found that even a submonolayer of simulated lunar dust can significantly degrade the performance of both white paint and second-surface mirror type thermal control surfaces under these conditions. Contrary to earlier studies, dust was found to affect as well as . Dust lowered the emissivity by as much as 16 percent in the case of AZ-93, and raised it by as much as 11 percent in the case of AgFEP. The degradation of thermal control surface by dust as measured by / rose linearly regardless of the thermal control coating or substrate, and extrapolated to degradation by a factor 3 at full coverage by dust. Submonolayer coatings of dust were found to not significantly change the steady state temperature at which a shadowed thermal control surface will radiate.

  11. Cloudy sky shortwave radiative closure for a Baseline Surface Radiation Network site

    Science.gov (United States)

    Wang, Ping; Knap, Wouter H.; Stammes, Piet

    2011-04-01

    A shortwave radiative closure analysis for cloudy skies is presented for the Cabauw Baseline Surface Radiation Network (BSRN) site (51.97°N, 4.93°E). The cloudy cases are carefully selected to be overcast, single-layer, homogeneous, nonprecipitating water clouds. We selected in total 639 cases on 9 days between May 2008 and May 2009 and on 30 January 2007. The Doubling-Adding KNMI (DAK) code is used to simulate global irradiances. The cloud optical thickness is derived from the cloud liquid water path from microwave radiometer (MWR) measurements and the MODIS L2 cloud effective radius product. The scattering phase matrix of the cloud particles is calculated using a Mie code with the two-parameter Gamma size distribution. The MWR integrated water vapor column and an aerosol climatology are also used in the simulations. The cloudy cases cover a large range of liquid water path (30-400 g/m2), water vapor column (0.7-3.1 cm), and solar zenith angle (41°-75°). The mean difference between simulated global irradiances and BSRN measurements is 6 W/m2 (5%), with a standard deviation of 14 W/m2 (13%). This difference is within the uncertainties of the model input parameters and measurement errors. The correlation coefficient between the measured and simulated global irradiances is 0.95. The good closure results demonstrate the high quality of the MODIS effective radius data and MWR liquid water path data and the accuracy of the DAK model for the selected water cloud cases. Furthermore, the effects of clouds, aerosols, water vapor, and surface albedo on the global irradiance have been analyzed carefully. The sensitivity study shows that in order to achieve the closure with an uncertainty of a few W/m2, more frequent effective radius data, simultaneous aerosol and cloud measurements, and surface albedo measurements are essential.

  12. Self-generated clouds of micron-sized particles as a promising way of a Solar Probe shielding from intense thermal radiation of the Sun

    Science.gov (United States)

    Dombrovsky, Leonid A.; Reviznikov, Dmitry L.; Kryukov, Alexei P.; Levashov, Vladimir Yu

    2017-10-01

    An effect of shielding of an intense solar radiation towards a solar probe with the use of micron-sized SiC particles generated during ablation of a composite thermal protection material is estimated on a basis of numerical solution to a combined radiative and heat transfer problem. The radiative properties of particles are calculated using the Mie theory, and the spectral two-flux model is employed in radiative transfer calculations for non-uniform particle clouds. A computational model for generation and evolution of the cloud is based on a conjugated heat transfer problem taking into account heating and thermal destruction of the matrix of thermal protection material and sublimation of SiC particles in the generated cloud. The effect of light pressure, which is especially important for small particles, is also taken into account. The computational data for mass loss due to the particle cloud sublimation showed the low value about 1 kg/m2 per hour at the distance between the vehicle and the Sun surface of about four radii of the Sun. This indicates that embedding of silicon carbide or other particles into a thermal protection layer and the resulting generation of a particle cloud can be considered as a promising way to improve the possibilities of space missions due to a significant decrease in the vehicle working distance from the solar photosphere.

  13. Finite-element solution for a combined radiative-conductive analysis with mixed diffuse-specular surface characteristics. [of spaceborne telescope

    Science.gov (United States)

    Lee, H.-P.; Jackson, C. E., Jr.

    1975-01-01

    The finite-element method has been applied to solve a combined radiative-conductive heat transfer problem for a large space telescope similar to those used in orbiting satellites. The derivation of the underlying matrices and associated solution algorithm for a 2-D triangular element is presented in detail. The resulting expressions for this triangular element typify such an analysis, which yields constitutive matrices when the heat equation is cast in the matrix form. The relevant matrices include those pertaining to thermal conductance, internal heat generation, radiative exchanges, and all possible external thermal loadings. Emphasis is placed on the treatment of non-linear radiative interchange between surfaces in an enclosure having mixed diffuse-specular surface characteristics. Essential differences in governing equations describing these distinctive surface characteristics are identified. Concluding remarks are drawn from an example simulating a Cassegrainian space telescope.

  14. Casimir-Polder forces in the presence of thermally excited surface modes

    CERN Document Server

    Laliotis, Athanasios; Maurin, Isabelle; Ducloy, Martial; Bloch, Daniel

    2014-01-01

    The temperature dependence of the Casimir-Polder interaction addresses fundamental issues for understanding vacuum and thermal fluctuations. It is highly sensitive to surface waves which, in the near field, govern the thermal emission of a hot surface. Here we use optical reflection spectroscopy to monitor the atom-surface interaction between a Cs*(7D3/2) atom and a hot sapphire surface at a distance ~ 100 nm. In our experiments, that explore a large range of temperatures (500-1000K) the hot surface is at thermal equilibrium with the vacuum. The observed increase of the interaction with temperature, by up to 50 %, relies on the coupling between atomic virtual transitions in the infrared range and thermally excited surface-polariton modes. We extrapolate our findings to a broad distance range, from the isolated free atom to the short distances relevant to physical chemistry. Our work also opens the prospect of controlling atom surface interactions by engineering thermal fields.

  15. Enhancing VHTR Passive Safety and Economy with Thermal Radiation Based Direct Reactor Auxiliary Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Haihua Zhao; Hongbin Zhang; Ling Zou; Xiaodong Sun

    2012-06-01

    One of the most important requirements for Gen. IV Very High Temperature Reactor (VHTR) is passive safety. Currently all the gas cooled version of VHTR designs use Reactor Vessel Auxiliary Cooling System (RVACS) for passive decay heat removal. The decay heat first is transferred to the core barrel by conduction and radiation, and then to the reactor vessel by thermal radiation and convection; finally the decay heat is transferred to natural circulated air or water systems. RVACS can be characterized as a surface based decay heat removal system. The RVACS is especially suitable for smaller power reactors since small systems have relatively larger surface area to volume ratio. However, RVACS limits the maximum achievable power level for modular VHTRs due to the mismatch between the reactor power (proportional to volume) and decay heat removal capability (proportional to surface area). When the relative decay heat removal capability decreases, the peak fuel temperature increases, even close to the design limit. Annular core designs with inner graphite reflector can mitigate this effect; therefore can further increase the reactor power. Another way to increase the reactor power is to increase power density. However, the reactor power is also limited by the decay heat removal capability. Besides the safety considerations, VHTRs also need to be economical in order to compete with other reactor concepts and other types of energy sources. The limit of decay heat removal capability set by using RVACS has affected the economy of VHTRs. A potential alternative solution is to use a volume-based passive decay heat removal system, called Direct Reactor Auxiliary Cooling Systems (DRACS), to remove or mitigate the limitation on decay heat removal capability. DRACS composes of natural circulation loops with two sets of heat exchangers, one on the reactor side and another on the environment side. For the reactor side, cooling pipes will be inserted into holes made in the outer or

  16. A practical algorithm for estimating surface soil moisture using combined optical and thermal infrared data

    Science.gov (United States)

    Leng, Pei; Song, Xiaoning; Duan, Si-Bo; Li, Zhao-Liang

    2016-10-01

    Surface soil moisture (SSM) is a critical variable for understanding the energy and water exchange between the land and atmosphere. A multi-linear model was recently developed to determine SSM using ellipse variables, namely, the center horizontal coordinate (x0), center vertical coordinate (y0), semi-major axis (a) and rotation angle (θ), derived from the elliptical relationship between diurnal cycles of land surface temperature (LST) and net surface shortwave radiation (NSSR). However, the multi-linear model has a major disadvantage. The model coefficients are calculated based on simulated data produced by a land surface model simulation that requires sufficient meteorological measurements. This study aims to determine the model coefficients directly using limited meteorological parameters rather than via the complicated simulation process, decreasing the dependence of the model coefficients on meteorological measurements. With the simulated data, a practical algorithm was developed to estimate SSM based on combined optical and thermal infrared data. The results suggest that the proposed approach can be used to determine the coefficients associated with all ellipse variables based on historical meteorological records, whereas the constant term varies daily and can only be determined using the daily maximum solar radiation in a prediction model. Simulated results from three FLUXNET sites over 30 cloud-free days revealed an average root mean square error (RMSE) of 0.042 m3/m3 when historical meteorological records were used to synchronously determine the model coefficients. In addition, estimated SSM values exhibited generally moderate accuracies (coefficient of determination R2 = 0.395, RMSE = 0.061 m3/m3) compared to SSM measurements at the Yucheng Comprehensive Experimental Station.

  17. Unsteady MHD free convective Couette flow between vertical porous plates with thermal radiation

    Directory of Open Access Journals (Sweden)

    Basant K. Jha

    2015-10-01

    Full Text Available This study investigates the unsteady MHD free convective Couette flow of viscous incompressible electrically conducting fluid between two infinite vertical porous plates in the presence of transverse magnetic field and thermal radiation. Solutions for time dependent energy and momentum equations are obtained by the implicit finite difference method. To check the accuracy of the numerical solutions, steady state solutions for energy and momentum equations are obtained by using the perturbation method. The effect of various parameters controlling the physical situation is discussed with the aid of line graphs. Significant results from this study are that both velocity and temperature increase with the increase in thermal radiation parameter and time. A series of numerical experiments show that steady state velocity and temperature occur when the dimensionless time approaches the values of Prandtl number of the fluid. During the course of numerical computation, an excellent agreement was found between unsteady and steady state solutions at large value of time.

  18. Magnetic field and thermal radiation effects on steady hydromagnetic Couette flow through a porous channel

    Directory of Open Access Journals (Sweden)

    Chigozie Israel-Cookey

    2010-09-01

    Full Text Available This paper investigates effects of thermal radiation and magnetic field on hydromagnetic Couette flow of a highly viscous fluid with temperature-dependent viscosity and thermal conductivity at constant pressure through a porous channel. The influence of the channel permeability is also assessed. The relevant governing partial differential equations have been transformed to non-linear coupled ordinary differential equations by virtue of the steady nature of the flow and are solved numerically using a marching finite difference scheme to give approximate solutions for the velocity and temperature profiles. We highlight the effects of Nahme numbers, magnetic field, radiation and permeability parameters on both profiles. The results obtained are used to give graphical illustrations of the distribution of the flow variables and are discussed.

  19. Radiation and Thermal Cycling Effects on EPC1001 Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif Z.; Lauenstein, Jean M.; Casey, Megan C.; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These include radiation, extreme temperatures, and thermal cycling, to name a few. Information pertaining to performance of electronic parts and systems under hostile environments is very scarce, especially for new devices. Such data is very critical so that proper design is implemented in order to ensure mission success and to mitigate risks associated with exposure of on-board systems to the operational environment. In this work, newly-developed enhancement-mode field effect transistors (FET) based on gallium nitride (GaN) technology were exposed to various particles of ionizing radiation and to long-term thermal cycling over a wide temperature range. Data obtained on control (un-irradiated) and irradiated samples of these power transistors are presented and the results are discussed.

  20. Asymptotic diffusion limit of cell temperature discretisation schemes for thermal radiation transport

    Energy Technology Data Exchange (ETDEWEB)

    Smedley-Stevenson, Richard P., E-mail: richard.smedley-stevenson@awe.co.uk [AWE PLC, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Department of Earth Science and Engineering, Imperial College London, SW7 2AZ (United Kingdom); McClarren, Ryan G., E-mail: rmcclarren@ne.tamu.edu [Department of Nuclear Engineering, Texas A & M University, College Station, TX 77843-3133 (United States)

    2015-04-01

    This paper attempts to unify the asymptotic diffusion limit analysis of thermal radiation transport schemes, for a linear-discontinuous representation of the material temperature reconstructed from cell centred temperature unknowns, in a process known as ‘source tilting’. The asymptotic limits of both Monte Carlo (continuous in space) and deterministic approaches (based on linear-discontinuous finite elements) for solving the transport equation are investigated in slab geometry. The resulting discrete diffusion equations are found to have nonphysical terms that are proportional to any cell-edge discontinuity in the temperature representation. Based on this analysis it is possible to design accurate schemes for representing the material temperature, for coupling thermal radiation transport codes to a cell centred representation of internal energy favoured by ALE (arbitrary Lagrange–Eulerian) hydrodynamics schemes.

  1. Reduction in emittance of thermal radiator coatings caused by the accumulation of a Martian dust simulant

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, D. Keith; Witte, Larry C.; Hinke, Jaime [Department of Mechanical Engineering, University of Houston, Houston, TX 77204-4006 (United States); Hurlbert, Kathryn [NASA, Johnson Space Center (United States)

    2006-12-15

    Measurements were made of the effective emittance of three types of radiator coatings as a Martian dust simulant was added to the radiator surfaces. The apparatus consisted of multiple radiator coupons on which Carbondale Red Clay dust was deposited. The coupon design employed guard heating to achieve the accuracy required for acceptable emittance calculations. The apparatus was contained in a vacuum chamber that featured a liquid-nitrogen cooled shroud that simulated the Martian sky temperature. Three high-emittance radiator coatings were tested: two while silicate paints, Z-93P and NS-43G, and a silver Teflon film. Radiator temperatures ranged from 250 to 350K with sky temperatures from 185 to 248K. As dust was added to the radiator surfaces, the effective emittance of all three coatings decreased from initial values near 0.9 to a value near 0.4. A low-emittance control surface, polished aluminum, demonstrated a rise in effective emittance for thin dust layers, and then a decline as the dust layer thickened. This behavior is attributed to the conductive resistance caused by the dust layer. (author)

  2. Index of thermal stress for cows (ITSC) under high solar radiation in tropical environments.

    Science.gov (United States)

    Da Silva, Roberto Gomes; Maia, Alex Sandro C; de Macedo Costa, Leonardo Lelis

    2015-05-01

    This paper presents a new thermal stress index for dairy cows in inter-tropical regions, with special mention to the semi-arid ones. Holstein cows were measured for rectal temperature (T R), respiratory rate (F R) and rates of heat exchange by convection (C), radiation (R), skin surface evaporation (E S) and respiratory evaporation (E R) in the north eastern region of Brazil, after exposure to sun for several hours. Average environmental measurements during the observations were air temperature (T A) 32.4 °C (24.4-38.9°), wind speed (U) 1.8 m.s(-1) (0.01-11.0), relative humidity 63.6 % (36.8-81.5) and short-wave solar radiation 701.3 W m(-2) (116-1,295). The effective radiant heat load (ERHL) was 838.5 ± 4.9 W m(-2). Values for the atmospheric transmittance (τ) were also determined for tropical regions, in order to permit adequate estimates of the solar radiation. The average value was τ = 0.611 ± 0.004 for clear days with some small moving clouds, with a range of 0.32 to 0.91 in the day period from 1000 to 1300 hours. Observed τ values were higher (0.62-0.66) for locations near the seacoast and in those regions well-provided with green fields. Effects of month, location and time of the day were all statistically significant (P < 0.01). A total of 1,092 data were obtained for cows exposed for 1 to 8 h to sun during the day; in 7 months (February, March, April, July, August, September and November), 4 days per month on the average. A principal component analysis summarised the T R, F R, C, R, E S and E R measurements into just one synthetic variable (y 1); several indexes were then obtained by multiple regression of y 1 on the four environmental variables and its combinations, by using Origin 8.1 software (OriginLab Corp.). The chosen equation was the index of thermal stress for cows, ITSC = 77.1747 + 4.8327 T A - 34.8189 U + 1.111 U (2) + 118.6981 P V - 14.7956 P V (2) - 0.1059 ERHL with r (2) = 0.812. The

  3. OPERATION HARDTACK. Project 8.2. Thermal Radiation from High-Altitude Bursts

    Science.gov (United States)

    1985-09-01

    FR100A maffnetic tape playback and Epsco analog-to-digital converter 40 2.22 Block diagram of data reduction facility, thermal radiation...for each shot. ’ - ’ For detailed data reduction In the laboratory, an Epsco timing sequence and buffer stor- . " . .. * age eystem (Figure 2.21...play back the data tapes Into f ^ an Epsco Datrac B6135, which accomplished the analog-to-dlgltal conversion. The system included an input amplifier

  4. Non-thermal corrections to Hawking radiation versus the information paradox

    Energy Technology Data Exchange (ETDEWEB)

    Dvali, Gia [Arnold Sommerfeld Center for Theoretical Physics, Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen (Germany); Max-Planck-Institut fuer Physik, Muenchen (Germany); Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY (United States)

    2016-01-15

    We provide a model-independent argument indicating that for a black hole of entropy N the non-thermal deviations from Hawking radiation, per each emission time, are of order 1/N, as opposed to e{sup -N}. This fact abolishes the standard a priory basis for the information paradox. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Thermal Injury in Human Subjects Due to 94-GHz Radio Frequency Radiation Exposures

    Science.gov (United States)

    2016-02-24

    AFRL-RH-FS-TR-2016-0001 Thermal Injury in Human Subjects Due to 94-GHz Radio Frequency Radiation Exposures James E. Parker General...them. This report was cleared for public release by the 88th ABW Public Affairs Office and is available to the general public, including foreign ...This report is published in the interest of scientific and technical information exchange , and its

  6. Precise estimation of total solar radiation on tilted surface

    African Journals Online (AJOL)

    rajeev

    Key words: Correction factor, meteorological parameters, solar radiation. INTRODUCTION ... Incident solar radiation is calculated directly from the geometry of the model and using hourly recordings of direct beam and diffuse horizontal solar ...

  7. Surface Radiation Budget (SURFRAD) Network 1-Hour Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radiation measurements at SURFRAD stations cover the range of the electromagnetic spectrum that affects the earth/atmosphere system. Direct solar radiation is...

  8. Numerical investigation of CO2 emission and thermal stability of a convective and radiative stockpile of reactive material in a cylindrical pipe

    Directory of Open Access Journals (Sweden)

    Ramoshweu Solomon Lebelo

    2015-12-01

    Full Text Available In this article, we investigate the combined effects of emission of CO2 and O2 depletion on thermal stability in a long cylindrical pipe of combustible reactive material. The cylindrical pipe loses heat by convection and radiation at the surface, and the nonlinear differential equations governing the heat and mass transfer problem are tackled numerically using Runge–Kutta–Fehlberg method coupled with shooting technique. The effects of various thermo-physical parameters on the temperature, CO2 and O2 fields, and thermal stability are presented graphically and discussed quantitatively.

  9. Impact of anisotropic slip on transient three dimensional MHD flow of ferrofluid over an inclined radiate stretching surface

    Directory of Open Access Journals (Sweden)

    A.M. Rashad

    2017-04-01

    Full Text Available The present study explores the impact of anistropic slip on transient three dimensional MHD flow of Cobalt-kerosene ferrofluid over an inclined radiate stretching surface. The governing partial differential equations for this study are solved by the Thomas algorithm with finite-difference type. The impacts of several significant parameters on flow and heat transfer characteristics are exhibited graphically. The conclusion is revealed that the local Nusselt number is significantly promoted due to influence of thermal radiation whereas diminished with elevating the solid volume fraction, magnet parameter and slip factors. Further, the skin friction coefficients visualizes a considerable enhancement with boosting the magnet and radiation parameters, but a prominent reduction is recorded by elevating the solid volume fraction and slip factors.

  10. Passive-solar directional-radiating cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Schertz, William W. (Batavia, IL)

    1986-01-01

    A radiative cooling system for use with an ice-making system having a radiating surface aimed at the sky for radiating energy at one or more wavelength bands for which the atmosphere is transparent and a cover thermally isolated from the radiating surface and transparent at least to the selected wavelength or wavelengths, the thermal isolation reducing the formation of condensation on the radiating surface and/or cover and permitting the radiation to continue when the radiating surface is below the dewpoint of the atmosphere, and a housing supporting the radiating surface, cover and heat transfer means to an ice storage reservoir.

  11. Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody.

    Science.gov (United States)

    Zhu, Linxiao; Raman, Aaswath P; Fan, Shanhui

    2015-10-06

    A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities.

  12. Finite Element Simulation Code for Computing Thermal Radiation from a Plasma

    Science.gov (United States)

    Nguyen, C. N.; Rappaport, H. L.

    2004-11-01

    A finite element code, ``THERMRAD,'' for computing thermal radiation from a plasma is under development. Radiation from plasma test particles is found in cylindrical geometry. Although the plasma equilibrium is assumed axisymmetric individual test particle excitation produces a non-axisymmetric electromagnetic response. Specially designed Whitney class basis functions are to be used to allow the solution to be solved on a two-dimensional grid. The basis functions enforce both a vanishing of the divergence of the electric field within grid elements where the complex index of refraction is assumed constant and continuity of tangential electric field across grid elements while allowing the normal component of the electric field to be discontinuous. An appropriate variational principle which incorporates the Sommerfeld radiation condition on the simulation boundary, as well as its discretization by the Rayleigh-Ritz technique is given. 1. ``Finte Element Method for Electromagnetics Problems,'' Volakis et al., Wiley, 1998.

  13. Comparison of Two Models for Radiative Heat Transfer in High Temperature Thermal Plasmas

    Directory of Open Access Journals (Sweden)

    Matthieu Melot

    2011-01-01

    Full Text Available Numerical simulation of the arc-flow interaction in high-voltage circuit breakers requires a radiation model capable of handling high-temperature participating thermal plasmas. The modeling of the radiative transfer plays a critical role in the overall accuracy of such CFD simulations. As a result of the increase of computational power, CPU intensive methods based on the radiative transfer equation, leading to more accurate results, are now becoming attractive alternatives to current approximate models. In this paper, the predictive capabilities of the finite volume method (RTE-FVM and the P1 model are investigated. A systematic comparison between these two models and analytical solutions are presented for a variety of relevant test cases. Two implementations of each approach are compared, and a critical evaluation is presented.

  14. Inverse effect in simultaneous thermal and radiation aging of EVA insulation

    Directory of Open Access Journals (Sweden)

    G. Przybytniak

    2015-04-01

    Full Text Available Poly(ethylene-co-vinyl acetate (EVA insulation of the cable applied in nuclear power plants was accelerated aged by gamma-rays at two various temperatures, namely 55 and 85°C. Radiation degradation in the dose range of 0–1500 kGy was monitored using a Differential Scanning Calorimetry method by measuring oxidative induction temperature (OITp, gel fraction, mechanical and electrical tests. It was confirmed that a dose rate effect in the range of 420–1500 Gy/h was negligible whereas progress of degradation with increasing dose was strongly temperature dependent. For the insulation accelerated aged at 85°C the OITp and permittivity measurements confirmed lower degradation than for the specimens radiation treated at 55°C at the same dose rates. It was postulated that an inverse thermal effect resulted from radiation induced cross-linking facilitated by melting of EVA crystallites at 85°C.

  15. Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

    Science.gov (United States)

    Mortley, Aba; Bonin, H. W.; Bui, V. T.

    2007-12-01

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging 13C solid state NMR spectra imply limited sample degradation with increasing radiation.

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

    CERN Document Server

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

    2015-01-01

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

  17. Entropy Generation Analysis for Variable Thermal Conductivity MHD Radiative Nanofluid Flow through Channel

    Directory of Open Access Journals (Sweden)

    Md. Sarwar Alam

    2016-01-01

    Full Text Available The present work inspects the entropy generation on radiative heat transfer in the flow of variable thermal conductivity optically thin viscous Cu–water nanofluid with an external magnetic field through a parallel isothermal plate channel. Our approach uses the power series from the governing non-linear differential equations for small values of thermal conductivity variation parameter which are then analysed by various generalizations of Hermite- Padé approximation method. The influences of the pertinent flow parameters on velocity, temperature, thermal conductivity criticality conditions and entropy generation are discussed quantitatively both numerically and graphically. A stability analysis has been performed for the rate of heat transfer which signifies that the lower solution branch is stable and physically acceptable, whereas the upper solution branch is unstable.

  18. Thermal photon radiation in high multiplicity p+Pb collisions at the Large Hadron Collider

    CERN Document Server

    Shen, C; Denicol, G S; Jeon, S; Gale, C

    2015-01-01

    The collective behaviour of hadronic particles has been observed in high multiplicity proton-lead collisions at the Large Hadron Collider (LHC), as well as in deuteron-gold collisions at the Relativistic Heavy-Ion Collider (RHIC). In this work we present the first calculation, in the hydrodynamic framework, of thermal photon radiation from such small collision systems. Owing to their compact size, these systems can reach temperatures comparable to those in central nucleus-nucleus collisions. The thermal photons can thus shine over the prompt background, and increase the low $p_T$ direct photon spectrum by a factor of 2-3 in 0-1% p+Pb collisions at 5.02 TeV. This thermal photon enhancement can therefore serve as a clean signature of the existence of a hot quark-gluon plasma during the evolution of these small collision systems, as well as validate hydrodynamic behavior in small systems.

  19. Near field radiative thermal transfer between nano-structured periodic materials

    CERN Document Server

    Chalabi, Hamidreza; Brongersma, Mark L

    2013-01-01

    This paper provides a method based on rigorous coupled wave analysis for the calculation of the radiative thermal capacitance between a layer that is patterned with arbitrary, periodically repeating features and a planar one. This method is applied to study binary gratings and arrays of beams with a rectangular cross section. The effects of the structure size and spacing on the thermal capacitance are investigated. In all of these calculations, a comparison is made with an effective medium theory which becomes increasingly accurate as the structure sizes fall well below the relevant resonance wavelength. Results show that new levels of control over the magnitude and spectral contributions to thermal capacitance can be achieved with corrugated structures relative to planar ones.

  20. Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

    Science.gov (United States)

    Talento, Stefanie; Barreiro, Marcelo

    2016-08-01

    This study investigates the Intertropical Convergence Zone (ITCZ) response to extratropical thermal forcing applied to an atmospheric general circulation model coupled to slab ocean and land models. We focus on the relative roles of the atmosphere, tropical sea surface temperatures (SSTs) and continental surface temperatures in the ITCZ response to the imposed forcing. The forcing consists of cooling in one hemisphere and warming in the other poleward of 40°, with zero global average. Three sets of experiments are performed: in the first the slab ocean and land models are applied globally; in the second the tropical SSTs are kept fixed while the slab land model is applied globally; in the third, in addition, surface temperatures over Africa are kept fixed. Realistic boundary surface conditions are used. We find that the ITCZ shifts towards the warmer hemisphere and that the stronger the forcing, the larger the shift. When the constraint of fixed tropical SST is imposed we find that the ITCZ response is strongly weakened, but it is still not negligible in particular over the Atlantic Ocean and Africa where the precipitation anomalies are of the order of 20 and 60 %, respectively, of the magnitude obtained without the SST restriction. Finally, when the constraint of the African surface temperature is incorporated we find that the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures. The clear-sky longwave radiation feedback is highlighted as the main physical mechanism operating behind the land-based extratropical to tropical communication.

  1. Tracing the differences between Vulcanian and Strombolian explosions using infrasonic and thermal radiation energy

    Science.gov (United States)

    Marchetti, E.; Ripepe, M.; Harris, A. J. L.; Delle Donne, D.

    2009-03-01

    Eruptive plume dynamics is a direct expression of explosive style, where duration and altitude of eruptive clouds and dispersion of erupted products is proportional to the degree of fragmentation. We present an analysis of infrasonic and thermal records for explosions at Villarrica (Chile), Stromboli (Italy), Santiaguito and Fuego (Guatemala) volcanoes. Across these four systems magma composition spans from basaltic to dacitic and explosive activity is typically described as ranging from Strombolian to Vulcanian. We use this analysis to provide a quantitative, geophysically-based description of, and discrimination between, the different explosive styles that characterize the four volcanoes. While infrasound is directly related to the emission of over-pressurized gas, and thus solely reflects the plume emission, both plume emission and ascent are detected thermally. Thus, the two data sets together provide a complete description of the plume dynamics. In particular, while infrasound solely reflects the gas-thrust phase driving plume emission, thermal radiation energy is also affected by buoyancy during plume ascent. Thermal radiation energy estimated for explosions at Stromboli and Villarrica (10 4-10 7 J) is lower than that for events at Santiaguito and Fuego (10 8-10 9 J), but infrasonic energies overlap. This suggests a greater contribution of buoyancy for eruptive clouds at Santiaguito and Fuego when compared with Stromboli and Villarrica. We further investigated the plume dynamics by comparing infrasonic energy, which reflects gas-thrust ( EGT), with the difference between thermal radiation and infrasonic energies, which mostly reflects buoyancy ( EB). Our data distribution reveals two separate clusters. Explosions at Stromboli and Villarrica share low values of buoyancy, pointing to a gas-thrust dominated emission, efficient coupling of the infrasonic source to the atmosphere, and a Strombolian-type source process to generate a plume rich in coarse fragments

  2. Practical Calculation of Thermal Deformation and Manufacture Error uin Surface Grinding

    Institute of Scientific and Technical Information of China (English)

    周里群; 李玉平

    2002-01-01

    The paper submits a method to calculate thermal deformation and manufacture error in surface grinding.The author established a simplified temperature field model.and derived the thermal deformaiton of the ground workpiece,It is found that there exists not only a upwarp thermal deformation,but also a parallel expansion thermal deformation.A upwarp thermal deformation causes a concave shape error on the profile of the workpiece,and a parallel expansion thermal deformation causes a dimension error in height.The calculations of examples are given and compared with presented experiment data.

  3. The Effects of Landcover Pattern on Urban Surface Net Radiation Retrieved by Remote Sensing

    Science.gov (United States)

    Zhao, X.

    2015-12-01

    Taking Xiamen city as the study area, this research retrieved surface net radiation using meteorological data and Landsat 5 TM images of the four seasons in the year 2009. Meanwhile the 65 different landscape metrics of each analysis unit were acquired using landscape analysis method. Then the most effective landscape metrics affecting surface net radiation were determined by correlation analysis, partial correlation analysis, stepwise regression method, etc. At both class and landscape levels, this paper comprehensively analyzed the temporal and spatial variations of the surface net radiation as well as the effects of land cover pattern on it in Xiamen from a multi-seasonal perspective. The results showed that: Xiamen's surface net radiation is the maximum in summer, followed by spring, autumn. The surface net radiation in winter is the minimum. Net radiation flux is higher for water and forestland and is lower for built-up land and bare land, etc. The spatial composition of land cover pattern shows significant influence on surface net radiation. The proportion of bare land and the proportion of forest land are effective and important factors which affect the changes of surface net radiation all the year round. But the spatial allocation of land cover pattern has no significant influence on surface net radiation. Moreover, the proportion of forest land is more capable for explaining surface net radiation than the proportion of bare land. Its total annual explanatory ability is better than the latter. So the proportion of forest land is the most important and continuously effective factor which affects and explains the cross-seasonal differences of surface net radiation. This study is helpful in exploring the formation and evolution mechanism of urban heat island. It also gave theoretical hints and realistic guidance for urban planning and sustainable development.

  4. Hawking non-thermal and thermal radiations of Reissner Nordström anti-de Sitter black hole by Hamilton-Jacobi method

    Science.gov (United States)

    Ilias Hossain, M.; Atiqur Rahman, M.

    2013-09-01

    We have investigated Hawking non-thermal and purely thermal Radiations of Reissner Nordström anti-de Sitter (RNAdS) black hole by massive particles tunneling method. The spacetime background has taken as dynamical, incorporate the self-gravitation effect of the emitted particles the imaginary part of the action has derived from Hamilton-Jacobi equation. We have supposed that energy and angular momentum are conserved and have shown that the non-thermal and thermal tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The results for RNAdS black hole is also in the same manner with Parikh and Wilczek's opinion and explored the new result for Hawking radiation of RNAdS black hole.

  5. Experimental and Numerical Investigation of Design Parameters for Hydronic Embedded Thermally Active Surfaces

    DEFF Research Database (Denmark)

    Marcos-Meson, Victor; Pomianowski, Michal Zbigniew; E. Poulsen, Søren

    2015-01-01

    This paper evaluates the principal design parameters affecting the thermal performance of embedded hydronic Thermally Active Surfaces (TAS), combining the Response Surface Method (RSM) with the Finite Elements Method (FEM). The study ranks the combined effects of the parameters on the heat flux...

  6. Photoemission and LEED study of the Sn/Rh(111) surface--early oxidation steps and thermal stability.

    Science.gov (United States)

    Hanyš, Petr; Píš, Igor; Mašek, Karel; Sutara, František; Matolín, Vladimír; Nehasil, Václav

    2012-01-11

    We have deposited two monolayers of Sn onto Rh(111) single crystal. After the deposition, no ordered structure was revealed by low energy electron diffraction (LEED). We oxidized the obtained system in a low-pressure oxygen atmosphere at 420 K. The oxidized sample was then gradually heated to study the thermal stability of the oxide layer. We characterized the system by synchrotron radiation stimulated photoelectron spectroscopy and LEED. Valence band and core level photoelectron spectra of rhodium, tin and oxygen were used to study the oxidation of the Sn-Rh(111) surface and its behaviour upon annealing. A low stoichiometric oxide of Sn was created on the surface. The oxidation process did not continue towards creation of SnO(2) with higher oxygen dose. The annealing at 970 K caused decomposition of the surface oxide of Sn and creation of an ordered (√3 × √3)R30° Sn-Rh(111) surface alloy.

  7. Radiative Effects of Water Clouds on Heat, Cloud Microphysical and Surface Rainfall Budgets Associated with Pre-Summer Torrential Rainfall

    Directory of Open Access Journals (Sweden)

    Jia Liu

    2014-01-01

    Full Text Available This study investigates thermal, cloud microphysical and surface-rainfall responses to the radiative effects of water clouds by analyzing two pairs of two-dimensional cloud-resolving model sensitivity experiments of a pre-summer heavy rainfall event. In the presence of the radiative effects of ice clouds, exclusion of the radiative effects of water clouds reduces the model domain mean rain rate through the mean hydrometeor increase, which is associated with the decreases in the melting of graupel and cloud ice caused by enhanced local atmospheric cooling. In the absence of the radiative effects of ice clouds, removal of the radiative effects of water clouds increases model domain mean rain rate via the enhancements in the mean net condensation and the mean hydrometeor loss. The enhanced mean net condensation and increased mean latent heat are related to the strengthened mean infrared radiative cooling in the lower troposphere. The increased mean hydrometeor loss associated with the reduction in the melting of graupel is caused by the enhanced local atmospheric cooling.

  8. Effect of number of stack on the thermal escape and non-radiative and radiative recombinations of photoexcited carriers in strain-balanced InGaAs/GaAsP multiple quantum-well-inserted solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, Taketo; Fukuyama, Atsuhiko; Ikari, Tetsuo [Faculty of Engineering, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan); Suzuki, Hidetoshi [Interdisciplinary Research Organization, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 889-2192 (Japan); Fujii, Hiromasa; Nakano, Yoshiaki [Research Center for Advanced Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan); Sugiyama, Masakazu [School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2015-02-28

    Three non-destructive methodologies, namely, surface photovoltage (SPV), photoluminescence, and piezoelectric photothermal (PPT) spectroscopies, were adopted to detect the thermal carrier escape from quantum well (QW) and radiative and non-radiative carrier recombinations, respectively, in strain-balanced InGaAs/GaAsP multiple-quantum-well (MQW)-inserted GaAs p-i-n solar cell structure samples. Although the optical absorbance signal intensity was proportional to the number of QW stack, the signal intensities of the SPV and PPT methods decreased at high number of stack. To explain the temperature dependency of these signal intensities, we proposed a model that considers the three carrier dynamics: the thermal escape from the QW, and the non-radiative and radiative carrier recombinations within the QW. From the fitting procedures, it was estimated that the activation energies of the thermal escape ΔE{sub barr} and non-radiative recombination ΔE{sub NR} were 68 and 29 meV, respectively, for a 30-stacked MQW sample. The estimated ΔE{sub barr} value agreed well with the difference between the first electron subband and the top of the potential barrier in the conduction band. We found that ΔE{sub barr} remained constant at approximately 70 meV even with increasing QW stack number. However, the ΔE{sub NR} value monotonically increased with the increase in the number of stack. Since this implies that non-radiative recombination becomes improbable as the number of stack increases, we found that the radiative recombination probability for electrons photoexcited within the QW increased at a large number of QW stack. Additional processes of escaping and recapturing of carriers at neighboring QW were discussed. As a result, the combination of the three non-destructive methodologies provided us new insights for optimizing the MQW components to further improve the cell performance.

  9. The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.; Hollenbeck, J.L.

    2000-11-01

    Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory metal and nickel-base materials. Emittance measurements following 4000 hours of vacuum annealing at 1100 C show that only the ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, and Al{sub 2}O{sub 3} + TiO{sub 2} coatings have the desired thermal stability, and maintain emissivity values higher than 0.8. These coatings are graybody emitters, and provide a high emissivity value in the wavelength range that is relevant to the TPV cells. The highest emissivity values were observed for the Al{sub 2}O{sub 3} + TiO{sub 2} coatings, with post-anneal values higher than graphite.

  10. Radiative heat transfer at nanoscale mediated by surface plasmons for highly doped silicon.

    OpenAIRE

    Rousseau, Emmanuel; Laroche, Marine; Greffet, Jean-Jacques

    2009-01-01

    International audience; In this letter, we revisit the role of surface plasmons for nanoscale radiative heat transfer between doped silicon surfaces. We derive a new accurate and closed-form expression of the radiative near-field heat transfer. We also analyse the flux and find that there is a doping level that maximizes the heat flux.

  11. The "Chocolate Experiment"--A Demonstration of Radiation Absorption by Different Colored Surfaces

    Science.gov (United States)

    Fung, Dennis

    2015-01-01

    In the typical "cookbook" experiment comparing the radiation absorption rates of different colored surfaces, students' hands are commonly used as a measurement instrument to demonstrate that dull black and silvery surfaces are good and poor absorbers of radiation, respectively. However, college students are often skeptical about using…

  12. The "Chocolate Experiment"--A Demonstration of Radiation Absorption by Different Colored Surfaces

    Science.gov (United States)

    Fung, Dennis

    2015-01-01

    In the typical "cookbook" experiment comparing the radiation absorption rates of different colored surfaces, students' hands are commonly used as a measurement instrument to demonstrate that dull black and silvery surfaces are good and poor absorbers of radiation, respectively. However, college students are often skeptical about using…

  13. Application of high refractive index and/or chromogenic layers to control solar and thermal radiations

    Science.gov (United States)

    Suzuki, Motofumi; Nishiura, Kensuke; Masunaka, Shoma; Muroi, Naoto; Namura, Kyoko

    2016-09-01

    In this presentation, we demonstrate that high refractive index materials such as β-FeSi2 and/or chromogenic materials such as VO2 are the key to control solar and thermal radiations. β-FeSi2 is known as an eco-friendly semiconductor and for sputtered polycrystalline β-FeSi2 thin films, we recently found that λ 0.3 in IR region, while n is higher than 5. On the other hand, another interesting optical property of β-FeSi2 is that both n and k are considerably high in visible to NIR region ( λ designed multilayers consisting of β-FeSi2/SiO2/β-FeSi2/W, where the upper β-FeSi2 layer absorbs VIS and NIR (λ <= 1.0 μm) and the bottom β-FeSi2 layer/W absorbs IR (1.0 <= λ <=2.0 μm). The optimized multilayers absorb more than 90% of solar energy and the eminence at 450 °C is lower than 10%. The perfect absorbers with high refractive index layers are useful for applications to solar selective absorbers for solar thermal power generation and spectrally selective thermal emitters for thermophotovoltaic power generation, IR heaters, radiation cooling. Replacing one of β-FeSi2 layers with a chromogenic material allows active control of solar and thermal radiation. In the presentation, we also demonstrate the active perfect absorbers including a VO2 layer in NIR region.

  14. Thermal radiation effects on magnetohydrodynamic free convection heat and mass transfer from a sphere in a variable porosity regime

    KAUST Repository

    Prasad, Vallampati Ramachandra Ramachandra

    2012-02-01

    A mathematical model is presented for multiphysical transport of an optically-dense, electrically-conducting fluid along a permeable isothermal sphere embedded in a variable-porosity medium. A constant, static, magnetic field is applied transverse to the cylinder surface. The non-Darcy effects are simulated via second order Forchheimer drag force term in the momentum boundary layer equation. The surface of the sphere is maintained at a constant temperature and concentration and is permeable, i.e. transpiration into and from the boundary layer regime is possible. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. Increasing porosity (ε) is found to elevate velocities, i.e. accelerate the flow but decrease temperatures, i.e. cool the boundary layer regime. Increasing Forchheimer inertial drag parameter (Λ) retards the flow considerably but enhances temperatures. Increasing Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. Thermal radiation is seen to reduce both velocity and temperature in the boundary layer. Local Nusselt number is also found to be enhanced with increasing both porosity and radiation parameters. © 2011 Elsevier B.V.

  15. Analysis of the hydrothermal behavior and entropy generation in a regenerative cooling channel considering thermal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoodi, M., E-mail: mostafamahmoodi@engineer.com [Department of Aerospace Engineering, Malek-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Kandelousi, Sh., E-mail: m.Kandelousi.sh@gmail.com [Department of Mechanical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-09-15

    Highlights: • Heat transfer enhancement of kerosene–alumina nanofluid is studied. • DTM is applied to solve the governing equations. • Nu is an increasing function of Rd, ϕ. • Be is a decreasing function of R, Ec. - Abstract: A semi-analytical investigation is performed into the force convection heat transfer characteristics and entropy generation of kerosene–alumina nanofluid in a channel of semi cryogenic engine. Thermal radiation effect is considered in energy equation. The governing equations are reduced to ordinary equation by means of similarity solution and solve by Differential Transformation Method. Velocity, temperature and concentration profiles as well as the skin friction coefficient, Nusselt number and Bejan number are determined for different values of pertinent parameters such as Radiation parameter, nanofluid volume fraction, Viscosity parameter and Eckert number. Results indicate that entropy generation is an increasing function of Viscosity parameter and Eckert number while it is a decreasing function of Radiation parameter. Also it can be concluded that Nusselt number enhances with augment of Radiation parameter and nanofluid volume fraction while it decreases with increase of Radiation and Viscosity parameter parameters.

  16. Optimum comfort limits determination through the characteristics of asymmetric thermal radiation in a heated floor space, "ondol".

    Science.gov (United States)

    Yoon, Y J; Park, S D; Sohn, J Y

    1992-09-01

    This study was undertaken to evaluate the effects of the asymmetric radiation on thermal comfort, and to suggest the optimum comfort limits in a radiant heating space. The index of V.R.T. (Vector Radiant Temperature) was used to describe the environmental quality of the heated floor space. Optimum comfort limits of this space were suggested through both theoretical and empirical studies. It is recommended to use not only man's sensation of the ambient air but also that of the floor surface for the determination of the optimum comfort limits on the heated floor space such as an "Ondol" in Korea. In the present study the optimum comfort limits were suggested in terms of the V.R.T. The optimum limits obtained were as follows: the vector radiant temperature 11.0 approximately 15.0 K.

  17. Effects of buoyancy and thermal radiation on MHD flow over a stretching porous sheet using homotopy analysis method

    Directory of Open Access Journals (Sweden)

    Yahaya Shagaiya Daniel

    2015-09-01

    Full Text Available This paper investigates the theoretical influence of buoyancy and thermal radiation on MHD flow over a stretching porous sheet. The model which constituted highly nonlinear governing equations is transformed using similarity solution and then solved using homotopy analysis method (HAM. The analysis is carried out up to the 5th order of approximation and the influences of different physical parameters such as Prandtl number, Grashof number, suction/injection parameter, thermal radiation parameter and heat generation/absorption coefficient and also Hartman number on dimensionless velocity, temperature and the rate of heat transfer are investigated and discussed quantitatively with the aid of graphs. Numerical results obtained are compared with the previous results published in the literature and are found to be in good agreement. It was found that when the buoyancy parameter and the fluid velocity increase, the thermal boundary layer decreases. In case of the thermal radiation, increasing the thermal radiation parameter produces significant increases in the thermal conditions of the fluid temperature which cause more fluid in the boundary layer due to buoyancy effect, causing the velocity in the fluid to increase. The hydrodynamic boundary layer and thermal boundary layer thickness increase as a result of increase in radiation.

  18. Thermalization of noninteracting quantum systems coupled to blackbody radiation: A Lindblad-based analysis

    Science.gov (United States)

    Ostilli, Massimo; Presilla, Carlo

    2017-06-01

    We study the thermalization of an ensemble of N elementary, arbitrarily complex, quantum systems, mutually noninteracting but coupled as electric or magnetic dipoles to a blackbody radiation. The elementary systems can be all the same or belong to different species, distinguishable or indistinguishable, located at fixed positions or having translational degrees of freedom. Even if the energy spectra of the constituent systems are nondegenerate, as we suppose, the ensemble unavoidably presents degeneracies of the energy levels and/or of the energy gaps. We show that, due to these degeneracies, a thermalization analysis performed by the popular quantum optical master equation reveals a number of serious pathologies, possibly including a lack of ergodicity. On the other hand, a consistent thermalization scenario is obtained by introducing a Lindblad-based approach, in which the Lindblad operators, instead of being derived from a microscopic calculation, are established as the elements of an operatorial basis with squared amplitudes fixed by imposing a detailed balance condition and requiring their correspondence with the dipole transition rates evaluated under the first-order perturbation theory. Due to the above-mentioned degeneracies, this procedure suffers a basis arbitrariness, which, however, can be removed by exploiting the fact that the thermalization of an ensemble of noninteracting systems cannot depend on the ensemble size. As a result, we provide a clear-cut partitioning of the thermalization time into dissipation and decoherence times, for which we derive formulas giving the dependence on the energy levels of the elementary systems, the size N of the ensemble, and the temperature of the blackbody radiation.

  19. Comparison of Observed Surface Temperatures of 4 Vesta to the KRC Thermal Model

    Science.gov (United States)

    Titus, T. N.; Becker, K. J.; Anderson, J. A.; Capria, M. T.; Tosi, F.; DeSanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.-P.; McCord, T. B.; Li, J.-Y.; Russell, C. T.; Ryamond, C. A.; Mittlefehldt, D.; Toplis, M.; Forni, O.; Sykes, M. V.

    2012-01-01

    In this work, we will compare ob-served temperatures of the surface of Vesta using data acquired by the Dawn [1] Visible and Infrared Map-ping Spectrometer (VIR-MS) [2] during the approach phase to model results from the KRC thermal model. High thermal inertia materials, such as bedrock, resist changes in temperature while temperatures of low thermal inertia material, such as dust, respond quickly to changes in solar insolation. The surface of Vesta is expected to have low to medium thermal inertia values, with the most commonly used value being extremely low at 15 TIU [4]. There are several parameters which affect observed temperatures in addition to thermal inertia: bond albedo, slope, and surface roughness. In addition to these parameters, real surfaces are rarely uniform monoliths that can be described by a single thermal inertia value. Real surfaces are often vertically layered or are mixtures of dust and rock. For Vesta's surface, with temperature extremes ranging from 50 K to 275 K and no atmosphere, even a uniform monolithic surface may have non-uniform thermal inertia due to temperature dependent thermal conductivity.

  20. Impact of an angiotensin analogue in treating thermal and combined radiation injuries

    Science.gov (United States)

    Jadhav, Sachin Suresh

    Background: In recent years there has been a growing concern regarding the use of nuclear weapons by terrorists. Such incidents in the past have shown that radiation exposure is often accompanied by other forms of trauma such as burns, wounds or infection; leading to increased mortality rates among the affected individuals. This increased risk with combined radiation injury has been attributed to the delayed wound healing observed in this injury. The Renin-Angiotensin System (RAS) has emerged as a critical regulator of wound healing. Angiotensin II (A-II) and Angiotensin (1-7) [A(1-7)] have been shown to accelerate the rate of wound healing in different animal models of cutaneous injury. Nor-Leu3-Angiotensin (1-7) [Nor-Leu3-A (1-7)], an analogue of A(1-7), is more efficient than both A-II and A(1-7) in its ability to improve wound healing and is currently in phase III clinical trials for the treatment of diabetic foot ulcers. Aims: The three main goals of this study were to; 1) Develop a combined radiation and burn injury (CRBI) model and a radiation-induced cutaneous injury model to study the pathophysiological effects of these injuries on dermal wound healing; 2) To treat thermal and CRBI injuries using Nor-Leu 3-A (1-7) and decipher the mechanism of action of this peptide and 3) Develop an in-vitro model of CRBI using dermal cells in order to study the effect of CRBI on individual cell types involved in wound healing. Results: CRBI results in delayed and exacerbated apoptosis, necrosis and inflammation in injured skin as compared to thermal injury by itself. Radiation-induced cutaneous injury shows a radiation-dose dependent increase in inflammation as well as a chronic inflammatory response in the higher radiation exposure groups. Nor-Leu3-A (1-7) can mitigate thermal and CRBI injuries by reducing inflammation, oxidative stress and DNA damage while increasing the rate of proliferation of dermal stem cells and re-epithelialization of injured skin. The in

  1. A Useful Tool for Atmospheric Correction and Surface Temperature Estimation of Landsat Infrared Thermal Data

    Science.gov (United States)

    Rivalland, Vincent; Tardy, Benjamin; Huc, Mireille; Hagolle, Olivier; Marcq, Sébastien; Boulet, Gilles

    2016-04-01

    Land Surface temperature (LST) is a critical variable for studying the energy and water budgets at the Earth surface, and is a key component of many aspects of climate research and services. The Landsat program jointly carried out by NASA and USGS has been providing thermal infrared data for 40 years, but no associated LST product has been yet routinely proposed to community. To derive LST values, radiances measured at sensor-level need to be corrected for the atmospheric absorption, the atmospheric emission and the surface emissivity effect. Until now, existing LST products have been generated with multi channel methods such as the Temperature/Emissivity Separation (TES) adapted to ASTER data or the generalized split-window algorithm adapted to MODIS multispectral data. Those approaches are ill-adapted to the Landsat mono-window data specificity. The atmospheric correction methodology usually used for Landsat data requires detailed information about the state of the atmosphere. This information may be obtained from radio-sounding or model atmospheric reanalysis and is supplied to a radiative transfer model in order to estimate atmospheric parameters for a given coordinate. In this work, we present a new automatic tool dedicated to Landsat thermal data correction which improves the common atmospheric correction methodology by introducing the spatial dimension in the process. The python tool developed during this study, named LANDARTs for LANDsat Automatic Retrieval of surface Temperature, is fully automatic and provides atmospheric corrections for a whole Landsat tile. Vertical atmospheric conditions are downloaded from the ERA Interim dataset from ECMWF meteorological organization which provides them at 0.125 degrees resolution, at a global scale and with a 6-hour-time step. The atmospheric correction parameters are estimated on the atmospheric grid using the commercial software MODTRAN, then interpolated to 30m resolution. We detail the processing steps

  2. Interaction effects of radiation and convection measured by a thermal manikin wearing protective clothing with different radiant properties

    NARCIS (Netherlands)

    Havenith, G.; Wang, X.; Candas, V.; Hartog, E. den; Griefahn, B.; Holmér, I.; Meinander, H.; Richards, M.

    2005-01-01

    As part of the EU funded research project THERMPROTECT ('Thermal properties of protective clothing and their use') this paper deals with manikin experiments on the effects of heat radiation at different wind speeds, considering aspects related to the reflectivity of the clothing. A heated thermal

  3. Coherent thermal radiation in thin films and its application in the emissivity design of multilayer films

    Institute of Scientific and Technical Information of China (English)

    LIANG XinGang; HAN MaoHua

    2007-01-01

    The Infrared transmission spectra of a 0.54-μm-thick Ge film and a 20-μm-thick Si film were experimentally measured.As the incident radiation was in the wavelength range from 1.5 μm to 10 μm,the Ge film demonstrated a strongly spectral coherence.However,thermal radiation of the Ge film was found to be spatially incoherent due to its extreme thinness.The Si film exhibited significantly spectral and spatial coherence.The results confirmed that thermal radiation of a monolayer film could be coherent spectrally and spatially if the film thickness was comparable with the wavelength.The optical characteristic matrix method was applied to calculate the transmission spectra of the Si and Ge film,and the results agreed well with the measurements.This method was further used to analyze two multilayer films composed of five low emissive layers.Their emissivities were found to be highly emissive at a certain zenith angle,and the emissive peak could be controlled by careful selection of film thickness.

  4. Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism

    Directory of Open Access Journals (Sweden)

    Subenoy Chakraborty

    2015-06-01

    Full Text Available The tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking’s periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.

  5. Investigation of Solar Hybrid Electric/Thermal System with Radiation Concentrator and Thermoelectric Generator

    Directory of Open Access Journals (Sweden)

    Edgar Arturo Chávez Urbiola

    2013-01-01

    Full Text Available An experimental study of a solar-concentrating system based on thermoelectric generators (TEGs was performed. The system included an electrical generating unit with 6 serially connected TEGs using a traditional semiconductor material, Bi2Te3, which was illuminated by concentrated solar radiation on one side and cooled by running water on the other side. A sun-tracking concentrator with a mosaic set of mirrors was used; its orientation towards the sun was achieved with two pairs of radiation sensors, a differential amplifier, and two servomotors. The hot side of the TEGs at midday has a temperature of around 200°C, and the cold side is approximately 50°C. The thermosiphon cooling system was designed to absorb the heat passing through the TEGs and provide optimal working conditions. The system generates 20 W of electrical energy and 200 W of thermal energy stored in water with a temperature of around 50°C. The hybrid system studied can be considered as an alternative to photovoltaic/thermal systems, especially in countries with abundant solar radiation, such as Mexico, China, and India.

  6. Analysis of thermal radiation in ion traps for optical frequency standards

    CERN Document Server

    Doležal, Miroslav; Nisbet-Jones, Peter B R; King, Steven A; Jones, Jonathan M; Klein, Hugh A; Gill, Patrick; Lindvall, Thomas; Wallin, Anders E; Merimaa, Mikko; Tamm, Christian; Sanner, Christian; Huntemann, Nils; Scharnhorst, Nils; Leroux, Ian D; Schmidt, Piet O; Burgermeister, Tobias; Mehlstäubler, Tanja E; Peik, Ekkehard

    2015-01-01

    In many of the high-precision optical frequency standards with trapped atoms or ions that are under development to date, the AC Stark shift induced by thermal radiation leads to a major contribution to the systematic uncertainty. We present an analysis of the inhomogeneous thermal environment experienced by ions in various types of ion traps. Finite element models which allow the determination of the temperature of the trap structure and the temperature of the radiation were developed for 5 ion trap designs, including operational traps at PTB and NPL and further optimized designs. Models were refined based on comparison with infrared camera measurement until an agreement of better than 10% of the measured temperature rise at critical test points was reached. The effective temperature rises of the radiation seen by the ion range from 0.8 K to 2.1 K at standard working conditions. The corresponding fractional frequency shift uncertainties resulting from the uncertainty in temperature are in the 10-18 range for ...

  7. Analysis of Radiative Radial Fin with Temperature-Dependent Thermal Conductivity Using Nonlinear Differential Transformation Methods

    Directory of Open Access Journals (Sweden)

    Mohsen Torabi

    2013-01-01

    Full Text Available Radiative radial fin with temperature-dependent thermal conductivity is analyzed. The calculations are carried out by using differential transformation method (DTM, which is a seminumerical-analytical solution technique that can be applied to various types of differential equations, as well as the Boubaker polynomials expansion scheme (BPES. By using DTM, the nonlinear constrained governing equations are reduced to recurrence relations and related boundary conditions are transformed into a set of algebraic equations. The principle of differential transformation is briefly introduced and then applied to the aforementioned equations. Solutions are subsequently obtained by a process of inverse transformation. The current results are then compared with previously obtained results using variational iteration method (VIM, Adomian decomposition method (ADM, homotopy analysis method (HAM, and numerical solution (NS in order to verify the accuracy of the proposed method. The findings reveal that both BPES and DTM can achieve suitable results in predicting the solution of such problems. After these verifications, we analyze fin efficiency and the effects of some physically applicable parameters in this problem such as radiation-conduction fin parameter, radiation sink temperature, heat generation, and thermal conductivity parameters.

  8. Direct solar thermal energy storage using a semitransparent PCM. Indoor experiment under constant incident radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Makoto; Bando, Yoshiyuki; Kuraishi, Michio; Hahne, E.W.P.

    1987-07-10

    The effect of the optical thickness of a translucent PCM (phase change material) on the temperature distribution and the thermal energy storage efficiency was studied for a passive system of solar thermal energy storage, in which a plane layer of the PCM was directly heated and melted by the solar radiation. Paraffin wax was used as the PCM and a black dye was added to change its absorption coefficient. Samples comprised of the PCM layer and the insulating layer with the adiabatic rear side were tested using a sun simulator capable of constant incident radiation. A theoretical analysis was made by applying the concept of overall specific heat. As the results, the theoretical analysis was proved to be valid, and further it was clarified that the optical thickness of the PCM had a strong influence on the temperature distribution and the thermal energy storage efficiency. The PCM with small optical thickness was found to have greater efficiency because of inner melting. (8 figs, 2 tabs, 7 refs)

  9. The Effect of Non-Lambertian Surface Reflectance on Aerosol Radiative Forcing

    Energy Technology Data Exchange (ETDEWEB)

    Ricchiazzi, P.; O' Hirok, W.; Gautier, C.

    2005-03-18

    Surface reflectance is an important factor in determining the strength of aerosol radiative forcing. Previous studies of radiative forcing assumed that the reflected surface radiance is isotropic and does not depend on incident illumination angle. This Lambertian reflection model is not a very good descriptor of reflectance from real land and ocean surfaces. In this study we present computational results for the seasonal average of short and long wave aerosol radiative forcing at the top of the atmosphere and at the surface. The effect of the Lambertian assumption is found through comparison with calculations using a more detailed bi-direction reflectance distribution function (BRDF).

  10. Tuning thermal transport in ultrathin silicon membranes by surface nanoscale engineering.

    Science.gov (United States)

    Neogi, Sanghamitra; Reparaz, J Sebastian; Pereira, Luiz Felipe C; Graczykowski, Bartlomiej; Wagner, Markus R; Sledzinska, Marianna; Shchepetov, Andrey; Prunnila, Mika; Ahopelto, Jouni; Sotomayor-Torres, Clivia M; Donadio, Davide

    2015-04-28

    A detailed understanding of the connections of fabrication and processing to structural and thermal properties of low-dimensional nanostructures is essential to design materials and devices for phononics, nanoscale thermal management, and thermoelectric applications. Silicon provides an ideal platform to study the relations between structure and heat transport since its thermal conductivity can be tuned over 2 orders of magnitude by nanostructuring. Combining realistic atomistic modeling and experiments, we unravel the origin of the thermal conductivity reduction in ultrathin suspended silicon membranes, down to a thickness of 4 nm. Heat transport is mostly controlled by surface scattering: rough layers of native oxide at surfaces limit the mean free path of thermal phonons below 100 nm. Removing the oxide layers by chemical processing allows us to tune the thermal conductivity over 1 order of magnitude. Our results guide materials design for future phononic applications, setting the length scale at which nanostructuring affects thermal phonons most effectively.

  11. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers

    Science.gov (United States)

    Hearon, Keith; Smith, Sarah E.; Maher, Cameron A.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-02-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities—that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because the thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150 °C for up to 5 h or to 125 °C for up to 24 h if stabilized with 10,000 ppm BQ and could also be heated to 125 °C for up to 5 h if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization of

  12. Evaluation of surface energy and radiation balance systems on the Konza Prairie

    Science.gov (United States)

    Fritschen, Leo J.

    1987-01-01

    Four Surface Energy and Radiation Balance Systems (SERBS) were installed and operated for two weeks in Kansas during July of 1986. Surface energy and radiation balances were investigated on six sites on the Konza Prairie about 3 km south of Manhattan, Kansas. Measurements were made to allow the computation of these radiation components: total solar and diffuse radiation, reflected solar radiation, net radiation, and longwave radiation upward and downward. Measurements were made to allow the computation of the sensible and latent heat fluxes by the Bowen ratio method using differential psychrometers on automatic exchange mechanisms. The report includes a description of the experimental sites, data acquisition systems and sensors, data acquisitions system operating instructions, and software used for data acquisition and analysis. In addition, data listings and plots of the energy balance components for all days and systems are given.

  13. Estimation of Solar Radiation Incident on Horizontal and Tilted Surfaces For 7 Colombian Zones

    Directory of Open Access Journals (Sweden)

    Corredor, L.M

    2013-09-01

    Full Text Available This paper discusses a procedure that was adopted for the development of a linear regression model for estimating solar radiation on horizontal surfaces for 7 Colombian zones. The correlations, the simulated global solar radiation on tilted surface and the simulated diffuse solar radiation on a horizontal surface for each zone are shown. The values of sunshine-hours and the solar radiation were taken from January 2012 to January 2013. The solar radiation values obtained were compared with the measured values. The obtained mean absolute percentage error was below 5%. The results of the global solarradiation show that the areas of greatest solar potential areTibú> Baranoa> ICP> GRB> Morichal> Castilla> Guamues and the months of the year with the highest solar radiation are June, July and August.

  14. Atmospheric impacts on climatic variability of surface incident solar radiation

    Directory of Open Access Journals (Sweden)

    K. C. Wang

    2012-10-01

    Full Text Available The Earth's climate is driven by surface incident solar radiation (Rs. Direct measurements have shown that Rs has undergone significant decadal variations. However, a large fraction of the global land surface is not covered by these observations. Satellite-derived Rs has a good global coverage but is of low accuracy in its depiction of decadal variability. This paper shows that daily to decadal variations of Rs, from both aerosols and cloud properties, can be accurately estimated using globally available measurements of Sunshine Duration (SunDu. In particular, SunDu shows that since the late 1980's Rs has brightened over Europe due to decreases in aerosols but dimmed over China due to their increases. We found that variation of cloud cover determines Rs at a monthly scale but that aerosols determine the variability of Rs at a decadal time scale, in particular, over Europe and China. Because of its global availability and long-term history, SunDu can provide an accurate and continuous proxy record of Rs, filling in values for the blank areas that are not covered by direct measurements. Compared to its direct measurement, Rs from SunDu appears to be less sensitive to instrument replacement and calibration, and shows that the widely reported sharp increase in Rs during the early 1990s in China was a result of instrument replacement. By merging direct measurements collected by Global Energy Budget Archive with those derived from SunDu, we obtained a good coverage of Rs over the Northern Hemisphere. From this data, the average increase of Rs from 1982 to 2008 is estimated to be 0.87 W m−2 per decade.

  15. Modelling thermal radiation from one-meter diameter methane pool fires

    Science.gov (United States)

    Consalvi, J. L.; Demarco, R.

    2012-06-01

    The first objective of this article is to implement a comprehensive radiation model in order to predict the radiant fractions and radiative fluxes on remote surfaces in large-scale methane pool fires. The second aim is to quantify the importance of Turbulence-Radiation Interactions (TRIs) in such buoyant flames. The fire-induced flow is modelled by using a buoyancy-modified k-ɛ model and the Steady Laminar Flamelet (SLF) model coupled with a presumed probability density function (pdf) approach. Spectral radiation is modelled by using the Full-Spectrum Correlated-k (FSCK) method. TRIs are taken into account by considering the Optically-Thin Fluctuation Approximation (OTFA). The emission term and the mean absorption coefficient are closed by using a presumed pdf of the mixture fraction, scalar dissipation rate and enthalpy defect. Two 1m-diameter fires with Heat Release Rates (HRR) of 49 kW and 162 kW were simulated. Predicted radiant fractions and radiative heat fluxes are found in reasonable agreement with experimental data. The importance of TRIs is evidenced, computed radiant fractions and radiative heat fluxes being considerably higher than those obtained from calculations based on mean properties. Finally, model results show that the complete absorption coefficient-Planck function correlation should be considered in order to properly take into account the influence of TRIs on the emission term, whereas the absorption coefficient self-correlation in the absorption term reduces significantly the radiant fractions.

  16. Prediction of solar global radiation on a surface tilted to the south

    Science.gov (United States)

    Kudish, Avraham I.; Evseev, Efim G.

    2008-08-01

    Solar global and diffuse radiation intensities are, in general, measured on horizontal surfaces, whereas stationary solar conversion systems (both flat plate solar collector and PV) are tilted towards the sun in order to maximize the amount of solar radiation incident on the collector surface. Consequently, the solar radiation incident on a surface tilted to the south (northern hemisphere) must be determined by converting the solar radiation intensities measured on a horizontal surface to that incident on the tilted surface of interest. There exist a large number of models designed to perform such a conversion. Eleven such models have been tested utilizing data measured in Beer Sheva, Israel. The data consist of hourly solar global and diffuse radiation on a horizontal surface, normal incidence beam and global radiation on a south-oriented surface tilted at 40°. The individual model performance is assessed by an inter-comparison between the calculated and measured solar global radiation on the south-oriented surface tilted at 40° using both graphical and statistical methods. The relative performance of the different models under different sky conditions, i.e., clear, partially cloudy and cloudy as defined by the hourly clearness index value, has been studied.

  17. Simulation of radiation dose distribution and thermal analysis for the bulk shielding of an optimized molten salt reactor

    Institute of Scientific and Technical Information of China (English)

    张志宏; 夏晓彬; 蔡军; 王建华; 李长园; 葛良全; 张庆贤

    2015-01-01

    The Chinese Academy of Science has launched a thorium-based molten-salt reactor (TMSR) research project with a mission to research and develop a fission energy system of the fourth generation. The TMSR project intends to construct a liquid fuel molten-salt reactor (TMSR-LF), which uses fluoride salt as both the fuel and coolant, and a solid fuel molten-salt reactor (TMSR-SF), which uses fluoride salt as coolant and TRISO fuel. An optimized 2 MWth TMSR-LF has been designed to solve major technological challenges in the Th-U fuel cycle. Preliminary conceptual shielding design has also been performed to develop bulk shielding. In this study, the radiation dose and temperature distribution of the shielding bulk due to the core were simulated and analyzed by performing Monte Carlo simulations and computational fluid dynamics (CFD) analysis. The MCNP calculated dose rate and neutron and gamma spectra indicate that the total dose rate due to the core at the external surface of the concrete wall was 1.91 µSv/h in the radial direction, 1.16 µSv/h above and 1.33 µSv/h below the bulk shielding. All the radiation dose rates due to the core were below the design criteria. Thermal analysis results show that the temperature at the outermost surface of the bulk shielding was 333.86 K, which was below the required limit value. The results indicate that the designed bulk shielding satisfies the radiation shielding requirements for the 2 MWth TMSR-LF.

  18. Ultrasonic analysis of acute thermal and radiation injury - A pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Goans, R.E. [MJW Corporation, Amherst, NY 14228 (United States); Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112 (United States)], E-mail: ronald.goans@comcast.net; Goans, R.H. [Department of Mathematics, University of Tennessee, Knoxville, TN 37996 (United States); Goans, R.E. [Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Christensen, D.M. [Radiation Emergency Assistance Center/Training Site (REAC/TS), Oak Ridge, TN 37830 (United States)

    2007-07-15

    Medical injury from a terrorist event (IND, RDD) is likely to involve both radiation damage and thermal trauma (combined injury). A high-frequency ultrasound technique has previously been developed to function as a clinical tool to distinguish partial-thickness from full-thickness thermal burns in a porcine model and the method was later extended for use in clinical burn units. In a traditional clinical setting, the technique has shown sufficient sensitivity to quantitate extension of a partial-thickness burn to a full-thickness burn through cutaneous infection. The ultrasound method has been extended in a pilot study to analyze radiation-induced cutaneous injury. Analysis of radiation-induced skin injury is more difficult than for thermal injury. However, further development of the method has shown a time-dependent response curve for the scattered ultrasound signal after irradiation of Wistar rat tails to 40 Gy with a 120 KeV X-ray spectrum. Statistically significant changes (p<0.05) in the magnitude of the reflected ultrasound spectrum have been noted less than 6 h-post-irradiation. The scattered intensity response curve peaks near the appearance of the first clinical sign (erythema) at 12 days post-irradiation. The mechanism of ultrasound sensitivity appears to involve changes in the tissue acoustic impedance post-irradiation possibly due to hyperemia, vascular damage and leakage. Because of the penetrating power and resolution of recent ultrasound equipment, this technique is expected to be extendable to analysis of irradiated deep organs, of large- and medium-size blood vessels, and to possible analysis of combined injury.

  19. Solar irradiance changes and photobiological effects at Earth's surface following astrophysical ionizing radiation events

    CERN Document Server

    Thomas, Brian C; Snyder, Brock R

    2015-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the TUV radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radi...

  20. Mechanical properties of cables exposed to simultaneous thermal and radiation aging

    Energy Technology Data Exchange (ETDEWEB)

    Jacobus, M.J. (Sandia National Labs., Albuquerque, NM (USA)); Fuehrer, G.F. (Science and Engineering Associates, Inc., Albuquerque, NM (USA))

    1990-01-01

    Sandia National Laboratories is conducting long-term aging research on representative samples of nuclear power plant Class 1E cables. The objectives of this program are to determine the suitability of these cables for extended life (beyond the 40-year design basis) and to assess various cable condition monitoring (CM) techniques for predicting remaining cable life. This paper provides the results of mechanical measurements that were performed on cable specimens cross-linked polyethylene neoprene jackets: chlorinated polyethylene jackets, fiberglass braid jackets, and chlorosulfonated polyethylene jackets aged at relatively mild, simultaneous thermal and radiation exposure conditions for periods of up to nine months. After aging, some of the aged samples, as well as some unaged samples, were exposed to accident gamma radiation at ambient temperature. The mechanical measurements discussed in this paper include tensile strength, ultimate elongation, and compressive modulus. 10 refs., 22 figs., 2 tabs.