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The Second Law of Thermodynamics in a Quantum Heat Engine Model
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作者 ZHANG Ting CAI Li-Feng +1 位作者 CHEN Ping-Xing LI Cheng-Zu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第3期417-420,共4页
The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world? In this paper, we calculate the change of entropy in T.D. Kieu's model for quantum... The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world? In this paper, we calculate the change of entropy in T.D. Kieu's model for quantum heat engine (QHE) and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu's initial model,nor greater than the reversible Carnot efficiency. 展开更多
关键词 second law of thermodynamics ENTROPY quantum heat engine
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Effects of the porous medium and water-silver biological nanofluid on the performance of a newly designed heat sink by using first and second laws of thermodynamics
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作者 Amin Shahsavar Sajad Entezari +1 位作者 Davood Toghraie Pouya Barnoon 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第11期2928-2937,共10页
The aim of this numerical investigation is to evaluate the laminar forced convection of biologically synthesized water-silver nanofluid through a heat sink(HS)filled with porous foam(PHS)using first and second laws of... The aim of this numerical investigation is to evaluate the laminar forced convection of biologically synthesized water-silver nanofluid through a heat sink(HS)filled with porous foam(PHS)using first and second laws of thermodynamics.The impacts of inlet velocity(V=0.5–3 m·s^-1)and volume fraction of nanofluid(φ=0–1%)on the performance metrics of HS are assessed and the outcomes are compared with those of the non-porous HS(NHS).The outcomes revealed that for both the PHS and NHS,the increase of V causes an intensification in convection coefficient,pumping power,and entropy generation due to fluid friction,while the maximum CPU temperature,thermal resistance,and entropy generation due to the heat transfer reduces by boosting V.Also,it was found that the augmentation of V results in intensification in convection coefficient,pumping power,overall hydrothermal performance,and frictional entropy generation,while the opposite is true for maximum CPU temperature,thermal resistance,and thermal entropy generation.Furthermore,it was reported that,except forφ=0.5%,the overall hydrothermal performance of NHS is better than that of PHS,while PHS has better second-law performance than NHS in all the studied cases.Also,it can be concluded that the best hydrothermal performance for PHS belongs toφ=1%and V=0.5 m·s^-1,while for NHS,these values are 1%and 2 m·s^-1. 展开更多
关键词 Porous medium Heat sink First and second laws of thermodynamics Biologically prepared water-silver nanofluid
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Applications of a Single Molecule Theory of Protein Dynamics
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作者 Yi Fang 《Journal of Biosciences and Medicines》 2024年第6期311-335,共25页
A single molecule theory for protein dynamics has been developed since 2012. It consists of the concepts of conformational Gibbs free energy function (CGF) and single molecule thermodynamic hypothesis (STH) that claim... A single molecule theory for protein dynamics has been developed since 2012. It consists of the concepts of conformational Gibbs free energy function (CGF) and single molecule thermodynamic hypothesis (STH) that claims that all stable conformations are (local or global) minimizers of CGF. These are enough to give a unified explanations and mechanisms to many aspects of protein dynamics such as protein folding;allostery;denaturation;and intrinsically disordered proteins. Formulas of CGF in water environment had been derived via quantum statistics. Applications of them to soluble proteins are: docking Gibbs free energy difference formula and a practical way to search better docking site;single molecule binding affinity;predicting and explaining why structures of a monomeric globular protein looks like a globule and is tightly packed with a hydrophobic core;a representation of the hydrophobic effect;and a wholistic view to structures of water soluble proteins. 展开更多
关键词 FOLDING DENATURATION BINDING Post-Binding Deformation ALLOSTERY Dynamic second law of thermodynamics
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Connection between the Principles of Thermodynamics and the Conservation Laws: Physical Meaning of the Principles of Thermodynamics
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作者 L. I. Petrova 《Journal of Applied Mathematics and Physics》 2018年第12期2697-2704,共8页
It has been shown that the first principle of thermodynamics follows from the conservation laws for energy and linear momentum. And the second principle of thermodynamics follows from the first principle of thermodyna... It has been shown that the first principle of thermodynamics follows from the conservation laws for energy and linear momentum. And the second principle of thermodynamics follows from the first principle of thermodynamics under realization of the integrating factor (namely, temperature) and is a conservation law. The significance of the first principle of thermodynamics consists in the fact that it specifies the thermodynamic system state, which depends on interaction between conservation laws and is non-equilibrium due to a non-commutativity of conservation laws. The realization of the second principle of thermodynamics points to a transition of the thermodynamic system state into a locally-equilibrium state. Phase transitions are examples of such transitions. 展开更多
关键词 SKEW-SYMMETRIC Differential FORMS Conservation lawS First PRINCIPLE of thermodynamics Realization of Integrating Factor the second PRINCIPLE of thermodynamics the Entropy
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A Fundamental Equation of Thermodynamics that Embraces Electrical and Magnetic Potentials 被引量:2
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作者 Salama Abdel- Hady 《Journal of Electromagnetic Analysis and Applications》 2010年第3期162-168,共7页
This paper introduces an energy-analysis of the flow of electrical charges and magnetic flux in addition to the flow of heat into a thermodynamic system. The analysis depends on the results of a held experiment on a m... This paper introduces an energy-analysis of the flow of electrical charges and magnetic flux in addition to the flow of heat into a thermodynamic system. The analysis depends on the results of a held experiment on a magnet that attracted iron balls and a Faraday’s discovery as well as similarities between the laws characterizing the flow of electric charges, magnetic flux and heat. As the electric charge and magnetic flux produce entropy changes in some applications as magnetic hysteresis and capacitive deionization, we may express the electric charges and magnetic flux in terms of entropy changes times their corresponding potentials by analogy to expressing heat as a product of temperature and entropy changes. Introducing such postulates into the held energy-analysis;a new fundamental equation of thermodynamics that embraces the flow of electric charges and magnetic flux in terms of the electric and magnetic potentials was derived. The derived equation proved its truth in numerous studies of general energy interactions. Such postulates help also in defining the electric charge and magnetic flux as categories of electromagnetic waves of assigned electric or magnetic potentials and offer plausible explanations of newly discovered phenomena in the fields of electromagnetism and thermodynamics as Kerr effect and magnetic expansion. 展开更多
关键词 First and second lawS of thermodynamics Electromagnetic WAVES Heat FLUX Electric CHARGE Magnetic FLUX
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Coherent Application of a Contact Structure to Formulate Classical Non-Equilibrium Thermodynamics
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作者 Edwin Knobbe Dirk Roekaerts 《Modern Mechanical Engineering》 2017年第1期8-26,共19页
This contribution presents an outline of a new mathematical formulation for Classical Non-Equilibrium Thermodynamics (CNET) based on a contact structure in differential geometry. First a non-equilibrium state space is... This contribution presents an outline of a new mathematical formulation for Classical Non-Equilibrium Thermodynamics (CNET) based on a contact structure in differential geometry. First a non-equilibrium state space is introduced as the third key element besides the first and second law of thermodynamics. This state space provides the mathematical structure to generalize the Gibbs fundamental relation to non-equilibrium thermodynamics. A unique formulation for the second law of thermodynamics is postulated and it showed how the complying concept for non-equilibrium entropy is retrieved. The foundation of this formulation is a physical quantity, which is in non-equilibrium thermodynamics nowhere equal to zero. This is another perspective compared to the inequality, which is used in most other formulations in the literature. Based on this mathematical framework, it is proven that the thermodynamic potential is defined by the Gibbs free energy. The set of conjugated coordinates in the mathematical structure for the Gibbs fundamental relation will be identified for single component, closed systems. Only in the final section of this contribution will the equilibrium constraint be introduced and applied to obtain some familiar formulations for classical (equilibrium) thermodynamics. 展开更多
关键词 NON-EQUILIBRIUM thermodynamics Gibbs FUNDAMENTAL Relation Contact Geometry second law of thermodynamics EQUILIBRIUM CONSTRAINT
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Quantum Statistics in Physical Chemistry, the Law of Mass Action and Epicatalysis
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作者 George S. Levy 《Open Journal of Physical Chemistry》 2018年第4期81-99,共19页
The law of mass action, based on maxwellian statistics, cannot explain recent epicatalysis experiments but does when generalized to non-maxwellian statistics. Challenges to the second law are traced to statistical het... The law of mass action, based on maxwellian statistics, cannot explain recent epicatalysis experiments but does when generalized to non-maxwellian statistics. Challenges to the second law are traced to statistical heterogeneity that falls outside assumptions of homogeneity and indistinguishability made by Boltzmann, Gibbs, Tolman and Von Neumann in their H-Theorems. Epicatalysis operates outside these assumptions. Hence, H-Theorems do not apply to it and the second law is bypassed, not broken. There is no contradiction with correctly understood established physics. Other phenomena also based on heterogeneous statistics include non-maxwellian adsorption, the field-induced thermoelectric effect and the reciprocal Hall effect. Elementary particles have well known distributions such as Fermi-Dirac and Bose Einstein, but composite particles such as those involved in chemical reactions, have complex intractable statistics not necessarily maxwellian and best determined by quantum modeling methods. A step by step solution for finding the quantum thermodynamic properties of a quantum composite gas, that avoids the computational requirement of modeling a large number of composite particles includes 1) quantum molecular modeling of a few particles, 2) determining their available microstates, 3) producing their partition function, 4) generating their statistics, and 5) producing the epicatalytic parameter for the generalized law of mass action. 展开更多
关键词 Adsorption BOLTZMANN ENTROPY Epicatalysis H-theOREM Heterogeneous STATISTICS law of Mass Action Non-Maxwellian Quantum thermodynamics second law
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An Alternative Demonstration of the Carnot Efficiency “Without” Using the Entropy Function
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作者 Olivier Serret 《Journal of Modern Physics》 2016年第2期185-198,共14页
Entropy function is used to demonstrate the Carnot efficiency, even if it is not always easy to understand its bases: the reversible movement or the reversible heat transfer. Here, it is proposed to demonstrate the Ca... Entropy function is used to demonstrate the Carnot efficiency, even if it is not always easy to understand its bases: the reversible movement or the reversible heat transfer. Here, it is proposed to demonstrate the Carnot efficiency “without” using the Entropy function. For this, it is necessary to enhance two concepts: heat transfer based on the source temperature and work transfer based on external pressure. This is achieved through 1) a balance exchanged heat, based on the source temperature and the system temperature, and 2) a balance exchanged work, based on the external pressure and the internal pressure. With these enhanced concepts, Laplace function and Carnot efficiency can be demonstrated without using the Entropy function (S). This is only a new formalism. Usual thermodynamics results are not changed. This new formalism can help to get a better description of realistic phenomena, like the efficiency of a realistic cycle. 展开更多
关键词 ENTROPY Carnot efficiency Laplace law Heat Work thermodynamic Engine Cycle efficiency
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Changes in Tropical Cyclone Number in the Western North Pacific in a Warming Environment as Implied by Classical Thermodynamics 被引量:1
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作者 Xiaogang Zhou Chongjian Liu +2 位作者 Ying Liu Hui Xu Xiuming Wang 《International Journal of Geosciences》 2011年第1期29-35,共7页
Observational analyses show that the equatorial trough in the western North Pacific (WNP) is a well-known origin for tropical cyclones (TC) which have tended to weaken in intensity and decrease in number during the la... Observational analyses show that the equatorial trough in the western North Pacific (WNP) is a well-known origin for tropical cyclones (TC) which have tended to weaken in intensity and decrease in number during the last several decades under global warming. A scientific problem then arises as to why higher sea surface temperatures (SSTs), one of the necessary conditions for typhoon genesis, can cause a weakened equatorial trough and a decreased TC number. In this paper, the WNP is taken as an example to illustrate a possible mechanism for the above-mentioned seemingly counterintuitive phenomena and explain the causality between the unusually heterogeneous pattern of SSTs in a warming environment and TC number in the WNP. This mechanism is based substantially on the second law of thermodynamics. 展开更多
关键词 second law of thermodynamics Global WARMING thermal Wind Relation Sea Surface Temperature
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THE UNIFIED ELASTIC-VISCOSIC-PLASTIC THEORY OF SOLIDS
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作者 金问鲁 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1999年第3期254-261,共8页
In this paper, mt unified elastic-viscosic-plastic theory which can compute the change of elastic, viscosic and plastic state of each point in the body is proposed. The theory is based on the laws of thermodynamics an... In this paper, mt unified elastic-viscosic-plastic theory which can compute the change of elastic, viscosic and plastic state of each point in the body is proposed. The theory is based on the laws of thermodynamics and the pseudo elastic postulate. lit the paper, the constitutive equations and variational principles are deduced. From which, the finite element method of both space and time may be easily formulated. Note that, by choosing the material parameters properly, the plastic constitutive equations currently used may be given. 展开更多
关键词 the first and second laws of thermodynamics pseudo elastic postulate
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Motion machines of second kind
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作者 Georgi Krastev Kiril Kolikov Yordan Epitropov 《Natural Science》 2012年第4期252-257,共6页
The second law of thermodynamics, i.e. the law stating that the entropy in isolated macroscopic system can never decrease, is tightly connected to the work of the device called perpetual motion machine of second kind.... The second law of thermodynamics, i.e. the law stating that the entropy in isolated macroscopic system can never decrease, is tightly connected to the work of the device called perpetual motion machine of second kind. Often this law is also defined as the inability to construct such a device. In the current paper we give complete, independent and consistent definitions of static, stationary and changing physical field. Based on that for the first time we give summarising, correct and complete definitions of natural resource machine and perpetual motion machine of second kind as well as motion machine of second kind in the set of tardyons and luxons. We present a principal structure of a motion machine of second kind using which we show that the Clausius statement and its equivalent statements in the thermodynamics can be violated for a practically big interval-time even under equilibrium fluctuations. 展开更多
关键词 Tardyons Luxons Physical Field second law of thermodynamics Perpetual MOTION Machine of second KIND
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Playing Rock, Paper, Scissors in Non-Transitive Statistical Thermodynamics
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作者 George S. Levy 《Journal of Applied Mathematics and Physics》 2017年第5期1174-1197,共24页
Does non-transitivity in information theory have an analog in thermodynamics? A non-transitive game, “Swap”, is used as a toy thermodynamic model to explore concepts such as temperature, heat flow, equilibrium and e... Does non-transitivity in information theory have an analog in thermodynamics? A non-transitive game, “Swap”, is used as a toy thermodynamic model to explore concepts such as temperature, heat flow, equilibrium and entropy. These concepts, found to be inadequate for non-transitive thermodynamic, need to be generalized. Two kinds of temperatures, statistical and kinetic, are distinguished. Statistical temperature is a parameter in statistical distributions. Kinetic temperature is proportional to the expected kinetic energy based on its distribution. Identical for Maxwell-Boltzmann statistics, these temperatures differ in non-Maxwellian statistics when a force is present. Fourier’s law of conduction and entropy should be expressed using statistical temperature, not kinetic temperature. Kinetic temperature is always scalar but statistical temperature and statistical entropy in non-transitive systems have circulation, thereby allowing continuous and circular heat flow. Entropy is relative to underlying statistics, in analogy to the Kullback-Leibler divergence in information theory. The H-theorem, limited by assumptions of homogeneity and indistinguishability, only covers statistically homogeneous systems. The theorem does not cover non-transitive, statistically heterogeneous systems combining different distributions such as Maxwell-Boltzmann, biased half-Maxwell-Boltzmann, Fermi-Dirac and Bose-Einstein. The second law can be preserved if generalized by expressing it in terms of statistical temperature and statistical entropy. 展开更多
关键词 STATISTICAL thermodynamics Non-Transitivity second law Detailed Balance Kinetic TEMPERATURE STATISTICAL TEMPERATURE Non-Transitive Game Non-Transitive thermodynamics Entropy Arrow of Time
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Using Quantum Statistics to Win at Thermodynamics, and Cheating in Vegas
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作者 George S. Levy 《Journal of Applied Mathematics and Physics》 2018年第10期2166-2179,共14页
Gambling is a useful analog to thermodynamics. When all players use the same dice, loaded or not, on the average no one wins. In thermodynamic terms, when the system is homogeneous—an assumption made by Boltzmann in ... Gambling is a useful analog to thermodynamics. When all players use the same dice, loaded or not, on the average no one wins. In thermodynamic terms, when the system is homogeneous—an assumption made by Boltzmann in his H-Theorem—entropy never decreases. To reliably win, one must cheat, for example, use a loaded dice when everyone else uses a fair dice;in thermodynamics, one must use a heterogeneous statistical strategy. This can be implemented by combining within a single system, different statistics such as Maxwell-Boltzmann’s, Fermi-Dirac’s and Bose-Einstein’s. Heterogeneous statistical systems fall outside of Boltzmann’s assumption and therefore can bypass the second law. The Maxwell-Boltzmann statistics, the equivalent of an unbiased fair dice, requires a gas column to be isothermal. The Fermi-Dirac and Bose-Einstein statistics, the equivalent of a loaded biased dice, can generate spontaneous temperature gradients when a field is present. For example, a thermoelectric junction can produce a spontaneous temperature gradient, an experimentally documented phenomenon. A magnetic field parallel to, and an electric field perpendicular to a surface produce a spontaneous current along the surface, perpendicular to both fields (Reciprocal Hall Effect). Experimental data collected by several independent researchers is cited to support the theory. 展开更多
关键词 Entropy Game H-theOREM Field-Induced thermoelectric EFFECT Reciprocal Hall EFFECT second law thermodynamics theRMOELECTRICS Homogeneity INDISTINGUISHABILITY
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Performance and Optimization of a Small Hybrid Solar-Thermal Collector
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作者 Amy Lebar Heather E. Dillon 《Smart Grid and Renewable Energy》 2018年第12期259-271,共13页
A hybrid solar collector was designed to investigate the effects of combining two different solar collector techniques on the overall collector’s effectiveness. While most solar collectors focus only on one solar col... A hybrid solar collector was designed to investigate the effects of combining two different solar collector techniques on the overall collector’s effectiveness. While most solar collectors focus only on one solar collection method, the small hybrid system uses a flat plate collector in conjunction with five evacuated tubes to absorb the most energy possible from both direct and diffuse solar radiation. Data was collected over four months while the system operated at different flow rates and with various levels of available insolation from the sun to evaluate the performance of the solar collector. To understand the relative contribution of the flat plate collector and the evacuated tubes, temperature differences across each part of the system were measured. The results indicate the average first law efficiency of the hybrid system is 43.3%, significantly higher than the performance of the flat plate alone. An exergy analysis was performed for this system to assess the performance of the flat plate system by itself. Results of the second law analysis were comparable to the exergetic efficiencies of other experimental collectors, around 4%. Though the efficiencies were in the expected range, they reveal that further improvements to the system are possible. 展开更多
关键词 Solar thermal Energy FLAT Plate COLLECTOR Evacuate Tube COLLECTOR EXERGY second law of thermodynamics
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On Thermodynamic Analysis of Substances with Negative Coefficient of Thermal Expansion
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作者 Kal Renganathan Sharma 《Engineering(科研)》 2013年第11期844-849,共6页
There are reports in the literature on the discovery of novel materials that were observed to shrink upon heating. Treatment of these materials in the same manner as the materials with positive coefficient of thermal ... There are reports in the literature on the discovery of novel materials that were observed to shrink upon heating. Treatment of these materials in the same manner as the materials with positive coefficient of thermal expansion can lead to the misinterpretation of the laws of thermodynamics. This is because volume expansivity is usually defined at constant pressure. Negative values for volume expansivity can be shown using Maxwell’s reciprocity relations to lead to negative values for absolute temperature for ideal gas. For real systems, using Helmholz free energy analysis at equilibrium an expression for the volume expansivity was derived. It can be seen that this expression would be always positive for real physical changes, either heating or cooling. Isentropic volume expansivity is proposed as better suited for analysis of materials with negative thermal expansion, NTE and composites used in space such as Hubble telescope and Chandra telescope with zero coefficient of thermal expansion. This kind of a switch from isobaric to isentropic has precedence in the history of development of speed of sound. 展开更多
关键词 NEGATIVE thermal EXPANSION NTE Materials Helmholz Free Energy second law of thermodynamics Speed of SOUND Volume Expansivity
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de Rham-Gabadadze-Tolley(dRGT)黑洞的热力学与弱宇宙监督假设
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作者 李慧玲 杨承宇 《沈阳师范大学学报(自然科学版)》 CAS 2024年第1期93-96,共4页
有质量引力理论作为修正引力理论之一,对探究宇宙加速膨胀,以及解释暗能量和暗物质问题等有重要意义.本文研究了在常规相空间中de Rham-Gabadadze-Tolley(dRGT)有质量引力下球对称黑洞的热力学第一定律、热力学第二定律与弱宇宙监督假... 有质量引力理论作为修正引力理论之一,对探究宇宙加速膨胀,以及解释暗能量和暗物质问题等有重要意义.本文研究了在常规相空间中de Rham-Gabadadze-Tolley(dRGT)有质量引力下球对称黑洞的热力学第一定律、热力学第二定律与弱宇宙监督假设是否成立;并通过图像探究熵的微分变化量随事件视界r_(d)变化的影响,以及与dRGT黑洞无量纲自由参数α,β与引力子质量对该图像的影响.在研究过程中,通过引入标量粒子的能量G动量关系,来验证黑洞热力学第一定律是否成立,通过观察事件视界对熵的微分变化量的影响,来验证黑洞热力学第二定律是否成立.研究发现,黑洞在吸收粒子的同时,其视界半径始终存在,从而使奇点始终没有裸露出来.结果表明,在dRGT有质量引力下球对称黑洞的热力学第一定律,热力学第二定律与弱宇宙监督假设均成立. 展开更多
关键词 弱宇宙监督假设 热力学第一定律 热力学第二定律 de Rham-Gabadadze-Tolley(dRGT)黑洞
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The Generalized Thermodynamic Temperature and the New Expressions of the First and the Second Law of Thermodynamics 被引量:3
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作者 HU Yacai CHEN Qi HU Yayuan 《Journal of Thermal Science》 SCIE EI CAS CSCD 2016年第1期1-6,共6页
The classical thermodynamics reflects the significant relationship between the heat and the temperature. On the basis of the relationships, according to the mathematical derivation, this paper structures the conceptio... The classical thermodynamics reflects the significant relationship between the heat and the temperature. On the basis of the relationships, according to the mathematical derivation, this paper structures the conceptions of generalized heat, generalized thermodynamic temperature, generalized entropy and so on. The series of conceptions in the classical thermodynamics is merely a special case of the generalized thermodynamics. Based on these conceptions of generalized thermodynamics, this paper presents the new expressions of the first law and the second law of thermodynamics. In other words, these expressions are endued with new explanations. The Eq. LZ = kTS given by this paper provides theoretical basis for these new expressions. 展开更多
关键词 Generalized thermodynamic temperature First law of thermodynamics second law of thermodynamics Generalized Carnot cycle Generalized Clausius inequality
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IMPROVEMENT OF A GLOBAL SPECTRAL MODEL BY INTRODUCING THE SECONDLAW OF THERMODYNAMICS
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作者 柳崇健 张道民 +1 位作者 李金龙 纪立人 《Acta meteorologica Sinica》 SCIE 1995年第1期95-100,共6页
The second law of thermodynamics has never been taken into account in the traditional hydrodynamics and numer- ical weather prediction models,which is a serious oversight in the history of mechanics.Introducing the th... The second law of thermodynamics has never been taken into account in the traditional hydrodynamics and numer- ical weather prediction models,which is a serious oversight in the history of mechanics.Introducing the thermodynamic irreversibility into the hydrodynamic systems,the theory and method proposed in this study would not only lead the outputs of a numerical weather prediction model to noticeable improvement,but lead the structure of hydrodynamics to deepgoing transformation. 展开更多
关键词 the second law of thermodynamics numerical weather prediction HYDRODYNAMICS
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复合钢结构不均匀受力下弹性形变预测与仿真
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作者 吕晓丹 高山凤 《计算机仿真》 2024年第8期466-470,共5页
不均匀受力容易导致复合钢结构中的局部应力集中、变形不均等问题,进而导致结构的失稳和损坏。为了保障复合钢结构的安全使用,提出复合钢结构不均匀受力下形变弹性预测仿真。结合熵增原理与热力第一、第二定律,通过分析不均匀受力状态... 不均匀受力容易导致复合钢结构中的局部应力集中、变形不均等问题,进而导致结构的失稳和损坏。为了保障复合钢结构的安全使用,提出复合钢结构不均匀受力下形变弹性预测仿真。结合熵增原理与热力第一、第二定律,通过分析不均匀受力状态下的复合钢结构内部能量分布情况,明确复合钢结构弹性形变分布情况。基于复合钢结构弹性形变过程中的力学分析,对弹性形变发生过程中的刚性振动现象展开分析,并利用广义力对因弹性形变造成的复合钢振动形态事实描述,获取其弹性形变动力学参数。将获取的参数输入反向传播(Back Propagation, BP)神经网络并对其训练,使BP神经网络具备复合钢结构形变弹性预测能力。通过反向权值修正,优化BP神经网络的预测精度,实现复合钢结构不均匀受力下形变弹性的精准预测。实验证明所提方法预测效果精准,且形变弹性分布预测结果与实际基本一致,为复合钢结构的广泛应用提供重要保障。 展开更多
关键词 熵增原理 热力第一定律 热力第二定律 刚性振动 神经网络
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基于耗散功的角度对热力学第二定律的教学探讨
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作者 屠飞泉 万猛 黄启洪 《遵义师范学院学报》 2024年第3期110-112,共3页
热力学第二定律的本质是自然界中自发实现的与热现象相关的过程都是不可逆的,而不可逆过程总伴随着能量“质”的下降。文章通过引入耗散功来描述一般封闭体系的热力学第二定律,这是从能量的角度而不是像通常那样基于熵的视角去描述热力... 热力学第二定律的本质是自然界中自发实现的与热现象相关的过程都是不可逆的,而不可逆过程总伴随着能量“质”的下降。文章通过引入耗散功来描述一般封闭体系的热力学第二定律,这是从能量的角度而不是像通常那样基于熵的视角去描述热力学第二定律。作者推导了耗散功所满足的关系,再通过三个简单的例子来说明对于非准静态等温过程其耗散功大于零。这些结论将有助于学生更好地掌握热力学第二定律。 展开更多
关键词 自由能 耗散功 热力学第二定律
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