Energy exchange processes between electrons and photons in the strong radiation fields encountered in some astrophysical objects. IV

Astrophysics ◽  
1990 ◽  
Vol 30 (3) ◽  
pp. 387-395
Author(s):  
G. T. Ter-Kazaryan
Keyword(s):  
Energy Exchange ◽  
Radiation Fields ◽  
Exchange Processes ◽  
Astrophysical Objects ◽  
Strong Radiation

Occupational Hot Exposures: Body Physiology and An Approach to Numerical Assessment

1989 ◽  
Vol 203 (3) ◽  
pp. 133-141 ◽  
Author(s):  
R C McLean ◽  
G H Galbraith ◽  
D Stewart
Keyword(s):  
Heat Stress ◽  
Working Conditions ◽  
Heat Balance ◽  
Energy Exchange ◽  
Environmental Parameters ◽  
The Body ◽  
Assessment Procedure ◽  
Exchange Processes ◽  
Numerical Assessment ◽  
Physiological Reactions

This paper summarizes the factors which influence the energy exchange processes between an individual and his surroundings and the mechanisms by which the body attempts to maintain itself in a heat balance situation. Thereafter, the important physiological reactions to hot working conditions are described and, on this basis, a numerical assessment procedure is proposed. Examples are given of the use of this method in investigating the possibility of heat stress and estimating the time for which an acclimatized worker can safely be exposed in such circumstances. An increase in the permissible exposure time through a manipulation of the environmental parameters is also considered.

scholarly journals Accretion-Disk Corona Advected by External Radiation Drag

1998 ◽  
Vol 188 ◽  
pp. 413-414
Author(s):  
Y. Watanabe ◽  
J. Fukue
Keyword(s):  
Angular Momentum ◽  
Radiation Field ◽  
Accretion Disk ◽  
Accretion Disks ◽  
External Radiation ◽  
Radiation Fields ◽  
Almost All ◽  
Strong Radiation ◽  
Radiative Interaction ◽  
Standard Disk

Accretion-disk corona (ADC) is required from observational as well as theoretical reasons. In almost all of traditional studies, however, a stationary corona has been assumed; i.e., the corona gas corotates with the underlying (Keplerian) accretion disk, and the radial motion is ignored. Recently, in the theory of accretion disks a radiative interaction between the gas and the external radiation field has attracted the attention of researchers. In particular the radiation drag between the gas and the external radiation field becomes important from the viewpoint of the angular-momentum removal. We thus examine the effect of radiation drag on the accretion-disk corona above/below the accretion disk (Watanabe, Fukue 1996a, b). We suppose that an accretion disk can be described by the standard disk, and that radiation fields are produced by the central luminous source and the accretion disk, itself. In general an accretion-disk corona under the influence of strong radiation fields dynamically infalls (advected) toward the center.

Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method

1996 ◽  
Vol 312 ◽  
pp. 149-172 ◽  
Author(s):  
Michael A. Gallis ◽  
John K. Harvey
Keyword(s):  
Monte Carlo ◽  
Chemical Reactions ◽  
Energy Exchange ◽  
Chemical Reactivity ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Exchange Processes ◽  
Simulation Monte Carlo

In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented and compared with results from experiments and other DSMC calculations. The latter use traditional methods for the modelling of chemical reactions and energy exchange. The differences are discussed and evaluated.

scholarly journals Rotational disruption of dust grains by radiative torques in strong radiation fields

2019 ◽  
Vol 3 (8) ◽  
pp. 766-775 ◽  
Author(s):  
Thiem Hoang ◽  
Le Ngoc Tram ◽  
Hyeseung Lee ◽  
Sang-Hyeon Ahn
Keyword(s):  
Dust Grains ◽  
Radiation Fields ◽  
Strong Radiation

Synthesis, structure, and nonrigidity of Os4(CO)15, Os4(CO)13(PMe3)[P(OMe)3], and Os4(CO)14(CNBut)

1995 ◽  
Vol 73 (7) ◽  
pp. 1223-1235 ◽  
Author(s):  
Frederick W.B. Einstein ◽  
Victor J. Johnston ◽  
Andrew K. Ma ◽  
Roland K. Pomeroy
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Energy Exchange ◽  
Variable Temperature ◽  
Carbonyl Cluster ◽  
Space Group ◽  
Exchange Processes ◽  
Nuclear Magnetic Resonance Spectra ◽  
Osmium Carbonyl ◽  
C Nmr

The binary carbonyl Os4(CO)15, 1, has been prepared by the addition of Os(CO)5 to Os3(CO)10(cyclooctene)2 at −15 °C. The related clusters Os4(CO)13(PMe3)[P(OMe)3], 2, and Os4(CO)14(CNBu′), 3, have been synthesized from Os4(CO)13(PMe3) and Os4(CO)15(CNBu′), respectively. The crystal structures of 1, 2, and 3 reveal similar planar metal skeletons with short (2.774 (1) − 2.793 (2) Å) and long (2.978 (2) − 3.019 (2) Å) peripheral Os—Os bonds; the hinge Os—Os bond in 1–3 ranges in length from 2.936 (2) to 2.948 (1) Å. The variable temperature 13C nuclear magnetic resonance spectra of 1 and 3 show that both are highly nonrigid in solution even at −120 °C. The mechanism of nonrigidity is believed to be an all-equatorial, merry-go-round carbonyl exchange. The variable temperature 13C nmr spectra of 2 indicate it is rigid on the nmr time scale in solution at −45 °C. Carbonyl exchange is, however, observed in the spectrum at −6 °C. From the mode of collapse of the signals it is believed that the lowest energy exchange processes in 3 involve axial-equatorial, merry-go-round CO exchanges in the two planes that each contain a short Os—Os bond. Crystallographic data for compound 1: space group C2/c; a = 12.802 (3) Å, b = 10.217 (3) Å, c = 16.380 (5) Å, β = 91.39 (2)°; R = 0.044, 1204 observed reflections. For compound 2: space group P21/c; a = 11.106 (7) Å, b = 16.931 (5) Å, c = 16.481 (5) Å, β = 97.71 (5)°; R = 0.051, 2117 observed reflections. For compound 3: space group P21/n; a = 11.747 (3) Å, b = 18.009 (5) Å, c = 12.448 (2) Å, β = 92.65 (2)°; R = 0.054, 2131 observed reflections. Keywords: osmium, carbonyl, cluster, nonrigidity.

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