Electromagnetic Radiation: A Carrier of Energy and Entropy*

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Gian Paolo Beretta ◽  
Elias P. Gyftopoulos
Keyword(s):  
Electromagnetic Radiation ◽  
Radiation Field ◽  
Temperature Difference ◽  
Stable Equilibrium ◽  
Black Bodies ◽  
Different Temperatures ◽  
Interacting Systems

Starting from the properties of the electromagnetic radiation field at stable equilibrium, we derive expressions for the flows of energy and entropy between two black bodies at different temperatures, interacting only through electromagnetic radiation. We find that in general the interaction through radiation is nonwork but not heat. It is heat only if the temperature difference between the interacting systems is infinitesimal.

Simulation analysis of propellant in electromagnetic radiation field

2021 ◽  
Author(s):  
Tuan Zhao ◽  
Jianhua Chen ◽  
Hongzhi Yao ◽  
Xiangfei Ji ◽  
Wei Rem
Keyword(s):  
Electromagnetic Radiation ◽  
Radiation Field ◽  
Simulation Analysis

What is Diffusion?

1994 ◽  
Vol 116 (2) ◽  
pp. 136-139 ◽  
Author(s):  
E. P. Gyftopoulos ◽  
M. I. Flik ◽  
G. P. Beretta
Keyword(s):  
Stable Equilibrium ◽  
Equilibrium States ◽  
Diffusion Interaction ◽  
Energy Entropy ◽  
Two Systems ◽  
Interacting Systems ◽  
Pass Through

In earlier publications, heat Q← is defined as an interaction that is entirely distinguishable from work W→. The energy exchanged Q← is TQ times the entropy exchanged S←, where TQ is the almost common temperature of the interacting systems. Here, we define diffusion as another interaction that is entirely distinguishable from both work and heat, and that involves exchanges of energy, entropy, and amount of a constituent. It is an interaction between two systems A and B that pass through stable equilibrium states while their respective parameters remain fixed, and that have almost equal temperatures TA ≈ TB ≈ TD and almost equal total potentials μA ≈ μB ≈ μD of the diffusing constituent. The exchanges of entropy S→, energy E→, and amount of constituent n→ out of one system satisfy the relation S→ = (E→ −μDn→)/TD. In the limit of n→ = 0, a diffusion interaction becomes heat.

Effect of electromagnetic radiation on the Lamb shift

1952 ◽  
Vol 214 (1116) ◽  
pp. 137-142 ◽  
Keyword(s):  
Electromagnetic Radiation ◽  
Radiation Field ◽  
Lamb Shift ◽  
Black Body ◽  
Black Body Radiation ◽  
External Radiation ◽  
Discrete States ◽  
The Continuum

If there is an external radiation field surrounding the atom, it influences the value of the Lamb shift. It is shown that for black-body radiation at temperature comparable to 10 5 degrees, the change in the Lamb shift due to the influence of radiation is of the same order as the Lamb shift itself. Whereas the transitions to the continuum largely contribute to the Lamb shift (in the absence of radiation), the change in the Lamb shift is largely due to transitions to discrete states.

Molecular Dynamics Study on Effect of Interface Between Silicon and Silicon Carbide Crystals on Phonon Heat Conduction on Nanoscale

2019 ◽  
Author(s):  
Xianhua Nie ◽  
Li Zhao ◽  
Shuai Deng ◽  
Yue Zhang ◽  
Zhenyu Du
Keyword(s):  
Molecular Dynamics ◽  
Silicon Carbide ◽  
Heat Conduction ◽  
Temperature Difference ◽  
Reference Group ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Average Temperature ◽  
Different Temperatures ◽  
Materials Used

Abstract Both silicon (Si) and silicon carbide (SiC) are promising materials used in nano-electro-mechanical system (NEMS), however, the understanding on its phonon heat conduction is rare, which restrict the performance improvement of NEMS. Moreover, the effects of the interface between crystals, which could significantly impact the phonon transport, on heat conduction are not sufficient in the existing publication pool. In this paper, two systems, Si/Si and Si/SiC, are simulated at different temperatures and temperature differences using molecular dynamics simulation and the results were analyzed. The temperature of Si inside Si/SiC system was set at 280K, and the temperatures of SiC were set as a certain absolute value based on temperature difference setting. Meanwhile, 6 groups of temperature difference are applied as simulated conditions. In addition, simulated results from Si/Si system are also applied in comparative analysis as a reference group. The results suggested that the existence of the interface of Si/SiC system would reduce the capability of heat conduction compared to the heat conduction of Si/Si and reverse temperature differences are discovered. When the average temperature is higher than 280K, the heat conduction rate of Si/SiC system is higher than that of Si/Si system initially and as the temperature differences between crystals increases to 60.90K, the heat conduction rate of Si/Si system is higher than that of Si/SiC system. Similar conclusion can also be obtained when the average temperature is lower than 280K. This work provides an open opportunity to study the effect of interface on phonon heat conduction between crystals at typical temperature differences and average temperatures.

Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

2021 ◽  
Author(s):  
Rui Ding ◽  
Qiang Sun ◽  
Hailiang Jia ◽  
Liyun Tang ◽  
Delu Li
Keyword(s):  
Compressive Strength ◽  
Temperature Difference ◽  
Room Temperature ◽  
Shear Failure ◽  
Total Porosity ◽  
High Porosity ◽  
Quenching Temperature ◽  
Red Sandstone ◽  
Different Temperatures ◽  
Development And Utilization

Abstract Liquid nitrogen (LN2) fracturing is beneficial to the development and utilization of geothermal energy. In this paper, the red sandstone was heated from room temperature to different temperatures (25°C-800°C) and then cooled with LN2. After attaining the room temperature, NMR, uniaxial compression, and acoustic emission (AE) tests were conducted, and results were compared for different samples. The results showed that with the increase in quenching temperature difference, the volume of micropores decreased gradually, while the volume of fine pores, mesopores, macropores and total porosity increased, resulting in the reduction of the compressive strength. Higher quenching temperature difference also reduced the sample’s total time to fail, and the failure mode was transformed from single inclined shear failure to conical failure. This is because the thermal stress (caused by the rapid cooling of LN2) expanded the original cracks of the sandstone, leading to high porosity and low compressive strength of the heat-treated and quenched samples.

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