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1.
曹治觉 《物理学报》2004,53(5):1321-1324
从力学和热力学角度简要证明了滴状冷凝时壁面球冠形液滴内外压强差不同于冷凝器内部球 形液滴的内外压强差,并指出有关文献对壁面自由能增量的理解存在概念上的混乱。 关键词: 滴状冷凝 压差 自由能  相似文献   

2.
It is shown that fractional derivatives of the (integrated) invariant measure of the Feigenbaum map at the onset of chaos have power-law tails in their cumulative distributions, whose exponents can be related to the spectrum of singularities (f(α). This is a new way of characterizing multifractality in dynamical systems, so far applied only to multifractal random functions [Frisch and Matsumoto, J. Stat. Phys. 108:1181, 2002]. The relation between the thermodynamic approach [Vul, Sinai and Khanin, Russian Math. Surveys 39:1, 1984] and that based on singularities of the invariant measures is also examined. The theory for fractional derivatives is developed from a heuristic point view and tested by very accurate simulations.  相似文献   

3.
The partition function is studied for an array of axisymmetric, hard bodies (capped cylinders, etc.) with each fixed at the base on a regular one-dimensional lattice. It is shown that if a phase transition occurs in a system ofn molecules, then it also occurs in a system of two molecules for the same value of the spacing parameter. With certain additional technical assumptions the converse is also true. Results are reported specifically for a system of thin, hard rods. Necessary and sufficient conditions are shown for a first-order transition to occur in the thermodynamic limit; there is only one transition and that happens when the spacing parameter is equal to the length of the rod. As expected, there is no phase transition when the rod is contracted to a point.  相似文献   

4.
分置式微型斯特林制冷机的理论分析   总被引:3,自引:0,他引:3  
本文建立了分置式微型斯特林制冷机的理论分析模型,给出了其内部各种参数(热力参数、流动参数、传热参数)的动态变化规律;并进行了主要结构参数的优化分析;同时还给出了各组成部件变质量、非稳定流动系统的■损失计算式。可推荐给工程实际应用。  相似文献   

5.
We discuss black hole solutions of Einstein-Λ gravity in the presence of nonlinear electrodynamics in d S spacetime. Considering the correlation of the thermodynamic quantities respectively corresponding to the black hole horizon and cosmological horizon of dS spacetime and taking the region between the two horizons as a thermodynamic system, we derive effective thermodynamic quantities of the system according to the first law of thermodynamics, and investigate the thermodynamic properties of the system under the influence of nonlinearity parameter α. It is shown that nonlinearity parameter α influences the position of the black hole horizon and the critical state of the system, and along with electric charge has an effect on the phase structure of the system,which is obvious, especially as the effective temperature is below the critical temperature. The critical phase transition is proved to be second-order equilibrium phase transition by using the Gibbs free energy criterion and Ehrenfest equations.  相似文献   

6.
It is shown that the practice in extended irreversible thermodynamics of raising the physical fluxes, such asq, the heat flux density, etc. to the status of independent thermodynamic variables does not meet the basic thermodynamic requirements nor in a real situation by keeping them constant one can vary the other thermodynamic independent variables. To elucidate this point the phenomena of rigid body heat conduction is used as an illustrative expample. It is argued that the thermometric temperature of systems whether in equilibrium or in nonequilibrium is the same physical entity.  相似文献   

7.
Summary Monolayers of a protein β-lactoglobulin (βL) and two lipids distearoylphosphatidylcholine (DSPC) and dimirystoylphosphatidylcholine (DMPC) on aqueous subphase containing Na+ or Ca2+ ions are studied. The spreading isotherms and the ATR-FTIR spectra of LB plurilayers transferred, allow to deduce that α-helix conformation of β-lactoglobulin is the prevailing form. The study of bidimensional mixtures between βL with DSPC and with DMPC shows that the components are incompatible at the W/A interface. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.  相似文献   

8.
杨则金  令狐荣锋  程新路  杨向东 《物理学报》2012,61(4):46301-046301
本文使用第一性原理的GGA/RPBE方法研究了Cr2MC(M=Al, Ga)的电子结构、弹性和热力学性质. 研究发现两个化合物的体积压缩性几乎相同, 并且证实了在0—50 GPa范围内c轴始终较a轴更难以压缩并且结构始终是稳定的. 通过对内坐标的研究发现了Cr2AlC中Cr离子的内坐标始终大于Cr2GaC中Cr离子的内坐标. 使用准谐德拜模型得到的体弹模量在0 GPa下随着温度的升高而减小, 而在300 GPa下则随着温度的升高而增大. 对德拜温度的研究发现Cr2GaC的值小于Cr2AlC的值, 而对热膨胀系数、Grüneisen参数、熵和热容的计算发现Cr2GaC的值大于Cr2AlC的值. 对电子结构的分析发现Cr2GaC的s和p电子在费米能级处的值大于Cr2AlC的s和p电子的值, 而其他离子的电子分布几乎一致.  相似文献   

9.
ABSTRACT

We study the molecular-scale features of the solid surface that result in the spontaneous motion of a nanodroplet due to the periodic variation of temperature. We first employ a thermodynamic model to predict the variation of solid–fluid interfacial properties that can result in the above motion. The model identifies a composite (surface couple) made of two surfaces that are characterised by a large difference between the entropic parts of the solid–liquid interfacial free energies. In order to understand the molecular-scale features of the two surfaces that may form a surface couple, we performed grand canonical Monte Carlo simulations of Lennard Jones fluid and crystalline surfaces made of Lennard Jones-like atoms. We then used the cumulant expansions of the perturbation formulas to divide the interfacial entropy into two parts: The one that is directly affected by the solid–fluid attraction (direct part), and the other (indirect part) that is indirectly affected by the solid–fluid attraction via the alteration of interfacial fluctuations. Our results indicate that two surfaces form a surface couple if the differences between their chemical natures lead to large differences in the indirect part of the interfacial entropy, while the direct part remains relatively unaffected.  相似文献   

10.
回顾了有限时间热力学的发展史,从物理学和工程学两个角度全面评述了其理论和应用研究发展现状,重点介绍了有限时间和/或有限尺寸约束条件下热力过程和装置的性能优化问题,指出了广义热力学优化将是其发展方向。  相似文献   

11.
In this article a brief review of the theory of one-dimensional nonlinear lattice is presented. Special attension is paid for the lattice of particles with exponential interaction between nearest neighbors (the Toda lattice). The historical exposition of findings of the model system, basic equations of motion, special solutions, and the general method of solutions are given as chronologically as possible. Some reference to the Korteweg-de Vries equation is also given. The article consists of three parts. Firstly, the idea of dual system is presented. It is shown that the roles of masses and springs of a harmonic linear chain can be exchanged under certain condition without changing the eigenfrequencies. Secondly, the idea is applied to the anharmonic lattice and an integrable lattice with exponential interaction force between adjacent particles is obtained. Special solutions to the equations of motion and general method of solution are shown. In the last part, some studies on the Yang-Yang’s thermodynamic formalism is given.  相似文献   

12.
有限时间热力学理论和应用的发展现状   总被引:41,自引:0,他引:41  
陈林根 Chih.  W 《物理学进展》1998,18(4):395-422
回顾了有限时间热力学的发展史,从物理学和工程学两个角度全面评述了其理论和应用研究发展现状,重点介绍了有限时间和/或有限尺寸约束条件下热力过程和装置的性能优化问题,指出了广义热力学优化将是其发展方向。  相似文献   

13.
In this paper, we visit the thermodynamic criticality and thermodynamic curvature of the charged AdS black hole in a new phase space. It is shown that when the square of the total charge of the charged black hole is considered as a thermodynamic quantity, the charged AdS black hole also admits a van der Waals-type critical behavior without the help of thermodynamic pressure and thermodynamic volume. Based on this, we study the fine phase structures of the charged AdS black hole with fixed AdS background in the new framework. On the one hand, we give the phase diagram structures of the charged AdS black hole accurately and analytically, which fills up the gap in dealing with the phase transition of the charged AdS black holes by taking the square of the charge as a thermodynamic quantity. On the other hand, we analyse the thermodynamic curvature of the black hole in two coordinate spaces. The thermodynamic curvatures obtained in two different coordinate spaces are equivalent to each other and are also positive. Based on an empirical conclusion under the framework of thermodynamic geometry, we speculate that when the square of charge is treated as an independent thermodynamic quantity, the charged AdS black hole is likely to present a repulsive between its molecules. More importantly, based on the thermodynamic curvature, we obtain a universal exponent at the critical point of phase transition.  相似文献   

14.
刘晓莹 《物理学报》2007,56(8):4337-4341
利用Wentzel-Kramers-Brillouin近似计算了Taub-NUT时空事件视界附近自旋为1/2,1,3/2,2等无质量场的熵密度、压强和能量密度.结果表明,自旋场附近的热力学量不仅具有与平直时空相同的主导项,还多了两项自旋依赖的附加项. 关键词: Taub-NUT时空 自旋场 热力学量  相似文献   

15.
运用外势中弱相互作用玻色体系的理论结论,研究弱磁场中弱相互作用玻色气体的高温热力学性质,给出系统总能和热容量的解析式,分析粒子之间的相互作用及磁场对系统热力学性质的影响.研究结果表明,排斥(吸引)对粒子和能量的空间分布有集中(分散)作用,并使得系统的化学势、总能、热容量都增大(减小);加强磁场既可使得粒子和能量的空间分布趋于分散又可削弱相互作用对粒子和能量空间分布的影响.相互作用对各个特征量的影响也有着不同的个性表现.  相似文献   

16.
Hydrogen‐rich compounds are extensively explored as candidates for a high‐temperature superconductors. Currently, the measured critical temperature of 203 K in hydrogen sulfide (H3S) is among the highest over all‐known superconductors. In present paper, using the strong‐coupling Eliashberg theory of superconductivity, we compared in detail the thermodynamic properties of two samples containing different hydrogen isotopes H3S and D3S at 150 GPa. Our research indicates that it is possible to reproduce the measured values of critical temperature 203 K and 147 K for H3S and D3S by using a Coulomb pseudopotential of 0.123 and 0.131, respectively. However, we also discuss a scenario in which the isotope effect is independent of pressure and the Coulomb pseudopotential for D3S is smaller than for H3S. For both scenarios, the energy gap, specific heat, thermodynamic critical field and related dimensionless ratios are calculated and compared with other conventional superconductors. We shown that the existence of the strong‐coupling and retardation effects in the systems analysed result in significant differences between values obtained within the framework of the Eliashberg formalism and the prediction of the Bardeen‐Cooper‐Schrieffer theory.  相似文献   

17.
18.
The level densities of even-odd and even-even isotopes^161,162Dy,^166Er and ^171,172Yb were calculated using microscopic theory of interacting fermions and compared with experiments.It is found that the data can be well reproduced with level density formalism for nuclei with static deformation.The nuclear temperature as well as the reproduced with level density formalism for nuclei with static deformation.The nuclear temperature as well as the entropy of nuclear system as a function of excitation energy has been extracted from the BCS theory.It is shown that the entropy exhibits an S-formed shape as a function of excitation energy.This is interpreted as a phase transition.Procedure of treating the even-odd and even-even nuclear systems has been presented and discussed.  相似文献   

19.
由弱磁场中弱相互作用费米气体的配分函数,导出有限粒子数条件下系统的配分函数G(β,N ).在此基础上,运用统计平均方法求解有限粒子数弱相互作用费米气体热力学量的解析表达式,给出各种温度条件下的热力学性质.研究结果表明,有限粒子数效应使各个热力学量都产生了一个修正项,除温度趋于0外,粒子数对化学势的修正项有直接影响,对内能和热容量的修正项并不产生直接影响.并且有限粒子数效应总是降低化学势,从而使化学势的0点向低温漂移,粒子数增大,会削弱这种效应,粒子间的相互排斥会加强这种效应.  相似文献   

20.
采用基于粒子群优化算法的结构预测程序CALYPSO, 并结合第一性原理的VASP程序, 在175 GPa发现NbSi2的奇异立方高压相. 在此结构中, Nb原子形成金刚石结构, 而Si原子则形成正四面体镶嵌在金刚石结构中. 声子谱计算结果表明该结构是动力学稳定的. 电子结构分析表明, 六角相和立方相NbSi2均为金属, 对金属性贡献较大的是Nb原子, 而且Nb和Si原子之间存在明显的p-d杂化现象, 电荷更多地聚集在Si四面体中. 利用“应力应变”方法, 计算了NbSi2的弹性常数, 分析了其体积模量、剪切模量、杨氏模量和德拜温度等热动力学性质随压力的变化并进行了详细的讨论. 根据剪切模量和体积模量的比值分析了NbSi2两种相结构的脆性和延展性, 发现压力会导致六角相NbSi2的延展性增加, 但对立方相结构的延展性影响较小; 采用经验算法计算了NbSi2两种相结构硬度变化情况, 结合这一比值进行了详细的分析. 弹性各向异性计算结果表明, 随着压力增加, 六角结构的各向异性增强, 而立方结构的各向异性减小.  相似文献   

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