板翅换热器入口位置不同翅片排列方式对流体流动与换热的影响

目的：研究板翅换热器入口位置（入口段、导流段以及换热段）在不同翅片排列方式下,换热器流道内流体流动以及温度变化情况,期望得到能够实现
　　最优传热效果的板翅换热器入口位置合理的翅片排列方式。方法：1.构建7种不同入口翅片排列（入口段：导流段：换热段分别为5：8：11,5：8：6,5：8：21,5：4：11,5：16：11,9：8：11和3：8：11）,研究不同翅片排列下换热器入口位置流场以及温度场变化。2.分析板翅换热器入口位置6种不同网格划分结果（网格数分别为11962,39344,2120,207998,90738和54496）对计算误差的影响,验证网格收敛性。结论：通过分析板翅换热器入口位置不同翅片排列方式下换热器入口位置流场与温度场变化可以看出,相比入口段与换热段,导流段翅片排列对换热器温度场影响较大。强化导流段翅片排列可以使换热器获得更好的传热效果。     

不可逆斯特林制冷机的（εR）max

研究一类含有热阻和回热损失的斯特林制冷机的（εR)max，得到一些新的性能参数，可为斯特林制冷机最佳工况的选择和优化设计提供理论指导。     

基于ArcGIS Engine林火蔓延模拟算法的比较分析

算法选择对林火蔓延的模拟具有重要作用,既影响模拟的精度与效率,也限制模拟的实用性.对传统的边界插值算法进行优化,并与迷宫算法进行对比分析.研究表明,从耗时方面分析,与边界插值算法（5、7、16 s）相比,迷宫算法在3个时段的耗时（204、458、1 325 s）较长;且随着模拟时间的增加,迷宫算法的耗时呈现倍数增长.从模拟结果的精度上看,边界插值算法虽然模拟结果较为粗糙,但能从整体上反映林火蔓延的趋势,火场覆盖率为59.75%.迷宫算法的模拟蔓延边界细节较为接近实际的蔓延边界,能够反映林火蔓延的详细动态变化,且火场覆盖率达79.51%.     

一般理想气体卡诺循环效率的讨论

概述了热容量为常量的理想气体的卡诺循环效率 .从一般理想气体的绝热方程出发 ,推导出热容量不是常量的理想气体卡诺循环的效率 ,并进一步从熵的角度说明卡诺定理 ,得出一切卡诺循环的效率必然都等于工作物质为理想气体时的效率 .     

新闻搜索系统的研究

电子新闻系统是Internet的重要应用之一。为使用户能从众多的新闻组消息中快捷地查找到所需信息，本文建立了基于通用分布式搜索引擎的新闻组搜索系统模型，研究了News信息获取器的工作机制和用户的查询机制。     

Coupled models of heat transfer and phase transformation for the run-out table in hot rolling

Mathematical models are been proposed to simulate the thermal and metallurgical behaviors of the strip occtLrring on the run-out table （ROT） in a hot strip mill. A variational method is utilized for the discretization of the governing transient conduction-convection equation, with heat transfer coefficients adaptively determined by the actual mill data. To consider the thermal effect of phase transformation during cooling, a constitutive equation for describing austenite decomposition kinetics of steel in air and water cooling zones is coupled with the heat transfer model. As the basic required inputs in the numerical simulations, thermal material properties are experimentally measured for three carbon steels and the least squares method is used to statistically derive regression models for the properties, including specific heat and thermal conductivity. The numerical simulation and experimental results show that the setup accuracy of the temperature prediction system of ROT is effectively improved.     

高阶Apostol-Bernoulli函数的一些恒等式

Apostol-Bernoulli函数及其推广形式是研究某些特殊函数的基础,在特殊函数理论研究中占有极其重要的地位。研究了高阶Apostol-Bernoulli函数的性质,利用高阶Apostol-Bernoulli函数的指数生成函数与高阶Apostol-Euler函数的指数生成函数的关系,给出了Apostol-Bernoulli函数的两个表述式及一个推论。     

Research on a simulated 60 kW PEMFC cogeneration system for domestic application

INTRODUCTION Distributed cogeneration technology is a hot topic in electrical and energy industries (Ferguson and Ugursal, 2004). China’s need to limit the power usage in some places to meet the peak power demand in summer of recent years stimulated and supported increasing research on distributed generation tech- nologies. Fuel cells, as renewable energy sources, are considered one of the most promising sources of distributed electrical power. Operational fuel cell systems have perform…     

The Importance of Language in Students' Reasoning About Heat in Thermodynamic Processes

Researchers believe that the way that students talk, specifically the language that they use, can offer a window into their reasoning processes. Yet the connection between what students are saying and what they are actually thinking can be ambiguous. We present the results of an exploratory interview study with 10 participants, designed to investigate the role of language in university physics students' reasoning about heat in thermodynamic processes. The study revealed two key findings: (1) students' approaches to solving certain heat-related problems are related to the way in which they explicitly define the word ‘heat’ and (2) students' tendency to reason with heat as a state function in inappropriate contexts appears to be connected to a model of heat implicitly encoded in language. This model represents heat or heat energy/thermal energy as a substance that moves from one location to another. In this model, students talk about thermodynamic systems as ‘containers' of heat, and temperature is a measure of the amount of heat ‘in' an object.     

祛银方联合雷公藤多甙片治疗寻常型银屑病疗效观察

目的:观察祛银方联合雷公藤多甙片治疗寻常型银屑病临床疗效及安全性。方法:74例寻常型银屑病血热证患者随机分为祛银方联合雷公藤多甙片治疗组和雷公藤多甙片对照组。治疗4周后,评价治疗前后患者临床疗效、生活质量指数(DLQI)评分、中医临床症候症状等方面的改变,同时观察不良反应。结果:治疗后治疗组、对照组临床总有效率分别为87%、73%;两组生活质量指数(DLQI)均低于治疗前(P0.01),治疗后两组的DLQI评分有显著性差异(P0.01);治疗组中医症候均有显著性差异(P0.01);对照组除瘙痒症候治疗有显著性差异外(P0.01),余均无显著性差异(P0.05)。结论:祛银方联合雷公藤多甙片治疗寻常型银屑病具有良好的临床效果,尤其在改善中医症状如瘙痒、口渴等方面效果显著,能有效减轻雷公藤的毒副作用,起到减毒增效的作用。