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蒸发式冷凝器发展和应用 总被引:26,自引:0,他引:26
本文介绍了冷凝器型式特点及应用现状,比较了不同型式的冷凝器,着重阐述了蒸发式冷凝器的结构、原理及其优点,分析了蒸发式冷凝器的发展及应用现状,总结了蒸发式冷凝器使用中存在的问题并提出了解决问题的方法,展望了蒸发式冷凝器的发展方向和应用前景。 相似文献
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基于振动的结构损伤识别方法研究进展 总被引:6,自引:1,他引:6
对近几十年来基于振动的结构损伤识别方法进行了归纳和总结,重点阐述了无模型的损伤识别方法和损伤识别的模型修正法,对损伤识别的神经网络法、小波分析法和时域法等也作了一定程度的介绍。分析了各种方法的优点和不足之处,讨论了基于振动的损伤识别技术存在的主要问题,并对进一步的研究方向作了展望。 相似文献
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客观规律的标准是相对正确的支配力关系,是实践检验具有很好复现性的规律.本文讨论和建立了主客观型标准的概念和分类关系,分析了神学、哲学、自然科学、美学、社会科学与其学科标准形成有关的发展历史,揭示标准性认识产生和发展的规律,讨论了五类学科的标准类别,提炼展示了部分典型的标准内容,以对主观认识的客观规律标准有实在的概念.本文深入讨论了主客观型标准的强弱性、标准的适用范围、标准的内容形式等特点,讨论了主客观型标准间的价值关系,从主观性与客观性、直观性与抽象性、意识与物质方面讨论了主客观型标准的哲理. 相似文献
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客观规律的标准是相对正确的支配力关系,是实践检验具有很好复现性的规律.本文讨论和建立了主客观型标准的概念和分类关系,分析了神学、哲学、自然科学、美学、社会科学与其学科标准形成有关的发展历史,揭示标准性认识产生和发展的规律,讨论了五类学科的标准类别,提炼展示了部分典型的标准内容,以对主观认识的客观规律标准有实在的概念.本文深入讨论了主客观型标准的强弱性、标准的适用范围、标准的内容形式等特点,讨论了主客观型标准间的价值关系,从主观性与客观性、直观性与抽象性、意识与物质方面讨论了主客观型标准的哲理. 相似文献
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Six refrigerants are evaluated as low GWP replacements for R404A using different configurations, including two-stage system architectures. These refrigerants are selected according to similar characteristics to R404A, and they are the mid-term alternatives R407A and R407F, and the long-term alternatives: L40 and DR-7 (with very low GWP and low flammability), N40 and DR-33 (with low GWP and no flammability). In order to have a complete comparison range, various operating conditions are considered, covering low and medium evaporator temperatures and two levels of condensation temperatures. Configurations selected are presented and the equations used to simulate the expected performance are shown. From a given cooling capacity, volumetric flow rate and COP are compared, taking R404A as baseline. The most efficient alternatives are the low-flammable refrigerants, L40 and DR-7, and when no flammability is acceptable, N40 and DR-33 are also very good options. 相似文献
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The thermodynamic analysis of a V-type Stirling-cycle refrigerator is performed. The Stirling-cycle refrigerator consists of expansion and compression spaces, cooler, heater and regenerator, and divided into 14 fixed control volumes subjected to a periodic mass flow. The conservation of mass and energy equation are written for each control volume. A computer program is prepared in FORTRAN, and the basic equations are solved iteratively. The mass, temperature and density of working fluid in each control volume are calculated for a given charge pressure, engine speed, and fixed heater and cooler surface temperatures, and the results are obtained from a PC. The heat transfer coefficients are assumed constant. The work, instantaneous pressure and COP of the Stirling-cycle refrigerator are also calculated. The steady cyclic conditions are obtained for temperature after few cycles and the results are given by diagrams. 相似文献
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标准化形式的理论谱系创建 总被引:1,自引:0,他引:1
本文对标准化形式的确定所面临的困惑进行了讨论,应用标准化的理性概念和标准化公理,推论和演绎出了20种标准化的理想形态,并对4个标准化公理进行分析,用两个标准化公理的4种关系和20种标准化理想形态,构建了标准化形态的理论谱系矩阵。应用标准化的理论形态对“简化”、“统一化”、“通用化”、“系列化”、“组合化”、“模块化”、“互换性”等原认为的标准化形态进行了理论验证,应用标准化形式的理论谱系对语言、文字、信息传输的标准化关系进行了解释。 相似文献
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Xin‐Sheng Xu Andrew Y. T. Leung Qian Gu Hao Yang Jian‐Jun Zheng 《International journal for numerical methods in engineering》2008,74(12):1848-1871
The symplectic series expansion method is extended to three‐dimensional problem for transversely isotropic piezoelectric media. The governing equations are first derived in Hamiltonian form, and symplectic eigensolutions are directly obtained through analytical method. All solutions of the problem are reduced to finding eigenvalues and eigensolutions. The classical St Venant solutions are described by zero‐eigensolutions, and the localized solutions are depicted by non‐zero‐eigensolutions. Symplectic relationships of the ortho‐normalization are used, end conditions are rewritten by eigensolutions, and a numerical scheme is formed analytically. Some numerical examples are given. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献