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This paper concerns the second law analysis of free convective squeezing flow of a chemically reacting Casson fluid confined between two parallel disks with Hall and Ion slip effects. The upper one is impermeable and the lower disk is porous. The linear momentum, energy balance and mass partial differential equations converted as system of ODEs by similarity transformations and tackled with shooting method via fourth order Runge‐Kutta scheme. The impact of various dimensionless geometric and fluid parameters on the velocity fields, temperature and concentration fields, entropy generation and Bejan numbers are studied and presented in the form of pictorially. The present results are correlated with already published outcomes for viscous case and found to be good agreement. The Bejan number of the fluid enhances with Ion slip parameter, whereas the concentration profile of the fluid is decreases with increasing of the Casson fluid parameter. The entropy generation of the fluid is enhanced with Eckert number whereas the Bejan number is decreased with suction/blowing parameter 相似文献
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In this paper, we study close connections that exist between the Riccati operator (differential) equation that arises in linear
control systems and the symplectic group and its subsemigroup of symplectic Hamiltonian operators. A canonical triple factorization
is derived for the symplectic Hamiltonian operators, and their closure under multiplication is deduced from this property.
This semigroup of Hamiltonian operators, which we call the symplectic semigroup, is studied from the viewpoint of Lie semigroup
theory, and resulting consequences for the theory of the Riccati equation are delineated. Among other things, these developments
provide an elementary proof for the existence of a solution of the Riccati equation for all t ≥ 0 under rather general hypotheses.
2000 Mathematics Subject Classification. 49N10, 93B27, 93B03, 22E15. 相似文献
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J.-P. Thouvenot 《Journal of Dynamical and Control Systems》1999,5(3):431-436
We show that when two transformations satisfy the weak Pinsker property, those among their joinings which also satisfy this property are dense. In particular, the
-bar distance can be arbitrarily well approached while staying in the class. 相似文献
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炉外小管道是除锅炉本体受热面管子之外的重要管道,它的爆管将直接导致安全事故。本文分析了它产生的原因,并提出了预防措施,供电厂工作人员及有关技术人员参考 相似文献
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本文对文献[1]中所提出的液压熵与回热加热系统的微循环理论进行了分析,对该理论提出了一些疑问,并阐述了自己的一些看法。 相似文献
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引入无量纲熵产数NS表示换热器热力完善程度,对换热器进行性能熵产分析与评价,研究了表征换热器换热性能的特性参数:进口温度比α、预热温度比β、水当量比W、效能ε、传热单元数NTU及流型对换热性能的影响及相关关系。研究表明,NS值随α增大而增大;提高β值(大于临界值),可降低NS值;NTU值应大于1,考虑经济性,其值不宜过大;W<1的非平衡流是造成有效能损失的原因;应使W趋于1;ε值大于0.5而趋于1,可减少不可逆性及提高换热率。通过熵产分析,可揭示换热器能耗产生的原因,确定热力参数的优化匹配,达到节能目的。 相似文献
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基于熵权法与正态云模型的大坝安全综合评价 总被引:2,自引:0,他引:2
针对目前大坝安全评价方法中均未考虑评价指标的模糊性和随机性问题,引入正态云模型理论,将其与熵权法相结合,建立了基于熵权法与正态云模型的大坝安全综合评价模型,综合考虑大坝变形、渗流及环境三方面因素构建了大坝风险安全评价体系,根据既定体系,确定大坝风险安全评价等级及云模型参数,代入大坝实测资料由正向云发生器建立评价指标的隶属度矩阵,采用熵权法确定各评价指标权重,并由评价指标的权重矩阵和评价指标的隶属度矩阵给出大坝在各安全评价等级下的隶属度。实例应用结果表明,大坝安全评价等级为低风险,与实际状况一致,可见所建模型可行、有效。 相似文献
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水电EPC工程项目通常签订固定总价合同,总承包商在项目实施过程中面临巨大的成本风险,因此针对水电EPC工程项目的特点进行成本风险的分析与评价尤为重要。在建立成本风险评价指标体系基础上,运用熵权法计算各指标权重,找出关键风险影响因素,从而为总承包商合理确定投标报价、施工成本预算,以及施工过程中的成本管理提供了科学依据。 相似文献
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运用修正的解析模型计算得到叶片冷却空气需求量和温度分布,并从热力学第二定律角度出发,阐述了动、静叶冷却过程的熵增情况,详细分析了冷却空气在冷却通道内的内部摩擦、导热损失模型以及冷却空气与燃气掺混时的内能和动能损失模型.对不同定义下的燃气轮机透平效率进行了比较、探讨,研究了叶片冷却对透平效率的影响,并对其进行了修正.算例结果表明,冷却导致的一系列不可逆熵增使得透平效率发生了2% -3%左右的下降.因此,在研究中需对冷却导致的透平效率变化进行修正,使得结果更加准确. 相似文献
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以宜昌水文站为例,针对不同时期河流生态系统对水文条件的需求,基于熵权、生态适宜性理论,构建了长江干流宜昌站近50年逐日适时划分水文指标模型,分析了流量、时间、频率、变化率等主要水文指数对河流生态流量的影响。结果表明,该方法可行。 相似文献
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Gamal M. Abdel-Rahman Rashed 《亚洲传热研究》2021,50(2):1697-1711
The present work, the entropy generation due to radiation and variable viscosity magnetohydrodynamic effects with a porous medium in a circular pipe, has been obtained and studied numerically. The governing continuity, momentum, and energy equations in cylindrical coordination are converted into a system of nonlinear ordinary differential equations by means of similarity transformation. The resulting system of coupled nonlinear ordinary differential equations is solved numerically by a Runge-Kutta method and shooting technique. Numerical results are presented for velocity, temperature profiles, pressure profile, entropy generation rates, and Bejan number for different physical parameters of the problem. Also, the effects of the pertinent parameters on the skin friction and the rate of heat transfer are obtained and discussed numerically and illustrated graphically. 相似文献
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