排序方式: 共有33条查询结果,搜索用时 15 毫秒
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基于量子主方程和半群逼近方法,研究以许多无相互作用的自旋-1/2系统为工质的、由两个绝热和两个等磁场过程组成的不可逆量子制冷循环的一般性能特性。导出循环的性能系数、制冷率和输入功率等重要性能参数的表达式。应用数值求解,对受有限循环时间约束的制冷率进行了优化,计算了最大制冷率和相应的最佳性能参数,确定了性能系数的最佳区域和工质温度及两个等磁场过程时间的优化范围。进而详细分析了高温下循环的优化性能,所得结果被进一步推广,以致可直接用来描述由自旋-J系统为工质的量子制冷循环的性能。 相似文献
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应用卡诺循环的Bucher图形象地表示出三热源循环,并由图中的相似三角形直接导出三热源循环的能量守恒方程、熵守恒方程和性能系数. 相似文献
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将弱耗散假设应用于由两个绝热过程和两个多方过程组成的一类广义卡诺热机循环,求出了循环的输出功率与效率的表达式,并给出了循环在最大输出功率时效率的上下界限,由此讨论了这一类循环的性能特性. 相似文献
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A time-delayed feedback ratchet consisting of two Brownian particles interacting through the elastic spring is consid ered. The model describes the directed transport of coupled Brownian particles in an asymmetric two-well ratchet potential which can be calculated theoretically and implemented experimentally. We explore how the centre-of-mass velocity is af fected by the time delay, natural length of the spring, amplitude strength, angular frequency, external force, and the structure of the potential. It is found that the enhancement of the current can be obtained by varying the coupling strength of the delayed feedback system. When the thermal fluctuation and the harmonic potential match appropriately, directed current evolves periodically with the natural length of the spring and can achieve a higher transport coherence. Moreover, the external force and the amplitude strength can enhance the directed transport of coupled Brownian particles under certain conditions. It is expected that the polymer of large biological molecules may demonstrate a variety of novel cooperative effects in real propelling devices. 相似文献
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By using the Euler-MacLaurin formula,this paper studies the thermodynamic properties of an ideal Fermi gas confined in a D-dimensional rectangular container.The general expressions of the thermodynamic quantities with the finite-size corrections are given explicitly and the effects of the size and shape of the container on the properties of the system are discussed.It is shown that the corrections of the thermodynamic quantities due to the finite-size effects are significant to be considered for the case of strong degeneracy but negligible for the case of weak degeneracy or non-degeneracy.It is important to find that some familiar conclusions under the thermodynamic limit are no longer valid for the finite-size systems and there are some novel characteristics resulting from the finite-size effects,such as the nonextensivity of the system,the anisotropy of the pressure,and so on. 相似文献
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由余函数的特性函数求范德瓦耳斯气体的热力学性质 总被引:1,自引:0,他引:1
本文以范德瓦耳斯气体为例,介绍由热力学余函数的特性函数内压能来计算实际气体的热力学余函数和热力学性质.并指出这方法是一种既简便又有效的计算热力学函数的方法. 相似文献
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