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水利工程合同执行中变更项目及费用探析 总被引:1,自引:0,他引:1
为合理确定水利工程合同变更中的项目及费用,介绍了工程变更的定义、产生的种类、范围和内容,运用对比合同条款的方法分析了变更细目确定及工程量计算要点,通过工程实例研究了变更项目适用合同单价及不平衡报价、材料价差、工程增量调价处理情况,对变更项目类似合同单价和不适用合同单价提出了解决方法,取得了实践经验,可供同类工程借鉴. 相似文献
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在国内石油产量只能保持相对稳定的背景下,随着经济的持续快速发展,大量进口石油是不可避免的。作为供应安全的主要对策之一就是力图使进口来源多元化。笔者曾强调要在进口地区、国家、途径(海和陆)、方式(现货和期货、多种形式的合同和协议)、品种(原油的酸油和甜油、各种油品)等多方面作到多元化,特称之为广义多元化。 相似文献
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中国国家技术进口公司(NTIC)于1986年12月中旬发布了从John Brown(约翰布朗)公司进口价值超过7200万美元的热电联供装置的合同。进口设备包括:5台Frame6B燃气轮机和余热锅炉、二套汽轮机发电机装置和气体燃料的压缩设备。隶属于JBE项目的分合同者包括:西门子公司(Siemens)提供汽轮机设备,BrushElectric(Brush电力公司)提供发电机设备,Standard Faset-Lentjes提供锅炉设备。所有五台热量回收蒸汽发生器(HRSG)都是对于相同的主蒸汽参数——压力为4 相似文献
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公伯峡水电站左岸泄洪洞进口边坡高程 1 981 m以下地质情况复杂 ,断层交错 ,对洞脸边坡和左边坡塌方锚固处理很有特点 ,同时对进口成洞、渐变段开挖和锚固的处理措施及参数 ,很具有代表性。特别是对地质构造和岩体稳定分析处理都有独特的特点 ;既保证边坡稳定和成洞安全 ,又保证了工期。岩体构造、地质构造分析和锚固参数对相类似的工程都有很高参考价值和借鉴意义 相似文献
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Sameh Shaaban 《国际能源研究杂志》2017,41(12):1767-1780
Despite the fact that wave energy is available at no cost, it is always desired to harvest the maximum possible amount of this energy. The axial flow air turbines are commonly used with oscillating water column devices as a power take‐off system. The present work introduces a blade profile optimization technique that improves the air turbine performance while considering the complex 3D flow phenomena. This technique produces non‐standard blade profiles from the coordinates of the standard ones. It implements a multi‐objective optimization algorithm in order to define the optimum blade profile. The proposed optimization technique was successfully applied to a biplane Wells turbine in the present work. It produced an optimum blade profile that improves the turbine torque by up to 9.3%, reduces the turbine damping coefficient by 10%, and increases the turbine operating range by 5%. The optimized profile increases the annual average turbine power by up to 3.6% under typical sea conditions. Moreover, new blade profiles were produced from the wind turbine airfoil data and investigated for use with the biplane Wells turbine. The present work showed that two of these profiles could be used with low wave energy seas. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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简要叙述了上海汽轮有限公司(STC)冷加工制造工艺的发展,重点介绍了汽缸、转子、叶片等汽轮机关键零件先进的加工技术,同时介绍了80年代中期以来引进的具有世界先进水平的设备以及STC依靠自己力量制造的高效率、低成本的设备。这些性能良好的设备加上先进的加工技术使STC冷加工制造技术达到90年代国际水平。 相似文献
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Because of their aeroelastic behavior, swept wind turbine blades offer the potential to increase energy capture and lower fatigue loads. This article describes work to develop a dynamic analysis code for swept wind turbine blades. This work was an outgrowth of a U.S. Department of Energy contract on swept blades, where the authors used the Adams? dynamic software (MSC Software Corporation, Santa Ana, CA, USA). The new code is based on the National Renewable Energy Laboratory's FAST code and allows for lower cost analysis and faster computation times for swept blades. The additions to the FAST code include the geometry and mode shapes required for the bending and twisting motion of the swept blade. In addition, a finite element program to determine mode shapes for the swept blade was developed. Comparisons of results obtained with the new code and analytical solutions for a curved cantilever beam show good agreement in local torsional deflections. Comparisons with field data obtained for a 750 kW wind turbine with swept blades were complicated by uncertainties in the test wind speed and turbine controller settings.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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阐述了引进型300MW、600MW汽轮机次末级“474”、“475”叶片安全性分析的思路,指出了“474”、“475”叶片二阶频率振型的不同是“474”叶片失效、“475”叶片安全运行的关键。 相似文献
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Wind turbine aerodynamics and loads control in wind shear flow 总被引:1,自引:0,他引:1
Wind turbine is subjected to some asymmetrical effects like wind shear, which will lead to unsteady blade airloads and performance. Fatigue loads can lead to damage of turbine components and eventually to failures. It is evident that the variation of the velocity over the rotor disc has an influence on the blade and introduces both flap-wise and edge-wise fatigue damage on the blade as a result of moment fluctuations in the two directions. The flap-wise moments on the blade are the origin of the rotor yaw and tilt moments which transmit to the turbine structure through the drive train to the yaw system and the tower. A lifting surface method with time marching free wake model is used to investigate the periodic unsteady nature in the wind shear. Individual pitch control (IPC) that is applied nowadays is the most advanced active control to reduce the fatigue. The blade airloads and performance of the turbine are also predicted under IPC control. It is found that IPC of the fluctuating blade root flap-wise moment can reduce the flap-wise fatigue damage remarkably while the blade root edge-wise moments are less sensitive to the varying blade pitch than the blade root flap-wise moments. 相似文献
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明确铸件定向凝固过程中的温度变化规律.可以避免重型燃气轮机定向叶片铸造中出现的一些缺陷。文章选取了与某重型燃机第1级涡轮动叶尺寸相近的试板.采用定向凝固高温合金DZ445.研究了该试板在实际工业生产用定向结晶炉中的定向凝固过程,结果表明:在距离水冷铜盘位置〉50mm后固液界面形态将发生大的转变,温度梯度逐渐变小,〉100mm后温度梯度基本保持不变.这为后续制定叶片抽拉工艺给出了参考。该实验还通过热电偶获得的定向凝固过程中温度一时间曲线与ProCAST模拟结果基本一致.验证了模拟边界条件和设置参数的准确性.后续可以用于模拟结构复杂的叶片定向凝固过程.指导实际生产工艺. 相似文献