共查询到18条相似文献,搜索用时 281 毫秒
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文献[1]指出,在物质流的能量方程中,pv这一项不是物质所携有的一种能量(流动能),而是克服压力所作的流动功.但是现有的物质系统的(火用)和(火无)的计算公式(例如文献[2])中,仍然将pv这一项视为物质流所携有的一种能量.文献[3]得到了一个(火用)和(火无)的统一公式.但是文献[3]将pv这一项视为环境功l_am.还有,文献[3]的(火无)的统一公式中不包括u_am,这也是不合理的. 相似文献
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《工程热物理学报》2021,42(6):1492-1498
网络热力学起源于热力系统分析,但其广泛应用却是在生命系统等非热系统领域,这是因为网络热力学方法需要从能量的角度分析系统,而热力系统中的热量在输运过程中具有物质属性,因此必须有新的能量形式。若将热量视作"流",而将温度视为"力",那么流与力的乘积就为(火积)流。(火积)具有能量的内涵,(火积)流就可以被视为热力系统的能量流。并且,在能量输运过程中,其他形式的能量如功量也可以视为一种物质。由此,在(火积)流的统一视角下,各种形式的能量在网络中便可得到有机结合。分析结果表明,对于换热系统以及热力系统,基于网络热力学的能量流法也可以表达系统的物理本质。在(火积)流的视角下,能量流键图可以很好地反映热力系统的拓扑结构。例如对于热机-热泵供热联合循环,热机与热泵之间的功量交换过程即使是可逆过程,也会存在(火积)的损失或产生,这从能量流键图中可以被直观地刻画出来。 相似文献
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A. Shnirelman 《Communications in Mathematical Physics》2000,210(3):541-603
Weak solution of the Euler equations is an L2-vector field u(x, t), satisfying certain integral relations, which express incompressibility and the momentum balance. Our conjecture is that some weak solutions are limits of solutions of viscous and compressible fluid equations, as both viscosity and compressibility tend to zero; thus, we believe that weak solutions describe turbulent flows with very high Reynolds numbers. Every physically meaningful weak solution should have kinetic energy decreasing in time. But the existence of such weak solutions have been unclear, and should be proven. In this work an example of weak solution with decreasing energy is constructed. To do this, we use generalized flows (GF), introduced by Y. Brenier. GF is a sort of a random walk in the flow domain, such that the mean kinetic energy of particles is finite, and the particle density is constant. We construct a GF such that fluid particles collide and stick; this sticking is a sink of energy. The GF which we have constructed is a GF with local interaction; this means that there are no external forces. The second important property is that the particle velocity depends only on its current position and time; thus we have some velocity field, and we prove that this field is a weak solution with decreasing energy of the Euler equations. The GF is constructed as a limit of multiphase flows (MF) with the mass exchange between phases. 相似文献
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In this paper, by introducing some proper transformations, the applied range of the homogenous balance (HB) method is extended. With the help ofMathematica, we obtain three auto-Bäcklund transformations (BT) for the generalized Fithugh-Nagumo equation, the generalized Burgers-Fisher equation, the generalized Burgers-Huxley equation, respectively, by use of the extended HB method. From these BTs, some exact solutions for these equations are derived. 相似文献
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R. Graham 《Zeitschrift für Physik B Condensed Matter》1980,40(1):149-155
Previous work on Fokker Planck equations with manifest detailed balance is generalized to include also the case without manifest detailed balance. The two cases are unified by exhibiting a general time reversal transformation with respect to which any Fokker Planck equation satisfies detailed balance, provided its steady state distribution exists. We also introduce a new method for solving some Fokker Planck equations with nonvanishing steady state drift by analytic continuation of the solution of a hermitian eigenvalue problem. 相似文献
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R. Graham 《Zeitschrift für Physik B Condensed Matter》1980,40(1-2):149-155
Previous work on Fokker Planck equations with manifest detailed balance is generalized to include also the case without manifest detailed balance. The two cases are unified by exhibiting a general time reversal transformation with respect to which any Fokker Planck equation satisfies detailed balance, provided its steady state distribution exists. We also introduce a new method for solving some Fokker Planck equations with nonvanishing steady state drift by analytic continuation of the solution of a hermitian eigenvalue problem. 相似文献
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单耗分析理论与结构系数法的对比分析 总被引:2,自引:0,他引:2
本文简要阐述了结构系数法和能源利用的单耗分析理论,并针对链式系统进行了初步的对比分析;尽管都是基于热力学第二定律的分析方法,并且它们的结果有一定的相似性,但结构系数法存在某些错误。比较而言,单耗分析理论显得更全面,也更实用。本文以锅炉供热系统为对象进行了详细的单耗分析,对系统中间子系统的(火用)耗损变化所带来的影响进行了详细的分析,结果证明结构系数法所作的“某一子系统(火用)效率变化,其他子系统(火用)效率不变”的假设是不恰当的, 其结论也是不准确的。 相似文献