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41.
Galloping of iced conductors under skew winds is always controlling condition. The aerodynamic parameters of iced conductors under skew winds is the key factor of galloping. This paper studies aerodynamic characteristics of crescent iced conductors under skew winds. Under skew winds aerodynamic coefficients of iced conductors carries on the examination on the traditional oblique wind decomposition method.using computational fluid dynamics software FLUENT numerical simulation and wind tunnel test on two kinds of methods, the iced conductor in under skew wind aerodynamic characteristics are studied, the wind tunnel test measured data and numerical simulation results a comparison is drawn, numerical simulation and experimental results are in good agreement. 相似文献
42.
Nonlinear characteristic of servo value is the important factor influencing hydraulic system, the model of electro-hydraulic servo pressure control system is designed. In this model, flux-equation of servo valve is specially applied and some non-linear characteristics are considered. Furthermore, SIMULINK toolbox of MATLAB language software is applied to solve mathematic model and simulation curves of some variables are obtained. The calculation results are in good agreement with the experimental results. 相似文献
43.
In machine cutting, the replacement of traditionalKGcutting solution with cryogenical cold air jet not only possesses a good cooling and lubricating efficiency, but also can avoid the occurrenceof environmental pollution. In order to clarify the manner and performance of discharged cutting chip under cryogenical cold air jet condition, an experiment was carried out for steel grade 45 in the dry and cryogenical cold air jet cutting comparatively. The effects of cryogenical cold air jet on the breaking of cutting chip are discussed. Experimental results reveal that, in the valid ranges of pressure and temperature, the cryogenical cold air jet can widen the chip broken region effectively. Different insufflating angle of cold air behaves different influence on the chip-break. From the experiment, it has been gained that the optimized jet insufflatingangle, temperature effecting range and pressure working range of cold air, which provides the foundation of industrial manufacturing. 相似文献
44.
This paper describes an application of evolutionary programming(EP) to reactive power optimization and voltage control of power systems.Some technical problems which conclude mutation sacle,fitness value and population size have been solved to make EP practical for solving the optimal power flow problems.The computational results with EP have been compared with those obtained from a conventional gradient based optimization method.The comparision shows that EP are better than conventional methods in dealing with the optimization of noncontinuous and nonsmooth funcnons.The EP show the ability to search for the global optimum in reactive optimization that has multiple optima. 相似文献
45.
The models,principle,deducing constitutive equation by means of variational method,and general solution are researched for bi moment in anisotropic spacial rod with opening thin walled seation. 相似文献
46.
研究花器官形态结构和开花特性,为白蜡授粉受精提供理论依据。本研究选取了3个白蜡品种(‘鲁蜡2号’、‘鲁蜡5号’和‘金箭’),对其开花特性、花器官构造进行观察。结果表明,白蜡品种雄株花期为11~13天,开花时间比雌株早13~15天;雌株‘鲁蜡2号’的花期为5~6天。3个白蜡品种的小花密集,开花后苞片2裂,花萼钟状4深裂,无花冠。雄花开花后露出舟形花药,花丝极短。雌花苞片开裂后露出雌蕊,柱头成熟时两裂,呈粉红色,花柱极短。扫描电镜下的3个白蜡品种苞片和花萼表面均有盾毛分布,不同品种间盾毛的形态有差异;‘金箭’、‘鲁蜡5号’的花药与花粉结构无显著差异;‘鲁蜡2号’整个雌蕊表面都有不规则褶皱分布。本研究可为进一步开展白蜡属植物的育种和种质资源创新利用研究提供参考。 相似文献
47.
According to the graphics characteristics of metallic doors & windows design and based on the research of graphics dimension restriction problems. This paper provides a new method for parameterized design of metallic doors & windows in virtue of expression solution. In this method, the restrictions of graphic elements have been changed into the parameter expressions of sizes and positions of graphic elements. Through the calculation of such expressions, the parameter driven method has been reached. Thus the parameterization of graphics can be easier and quicker than before. It can be used to setup the open parameterized graphics libraries. 相似文献
48.
水稻淀粉脱分支酶基因PUL对稻米理化品质的影响 总被引:1,自引:0,他引:1
为了研究PUL基因的变异对稻米蒸煮食味品质的影响,分别以籼稻品种桂朝2号和粳型糯稻品种苏御糯互为供体和轮回亲本,通过分子标记辅助选择,经过多代回交构建了PUL基因的近等基因系,分析了各近等基因系和轮回亲本的蒸煮品质指标。结果表明,近等基因系与轮回亲本在直链淀粉含量、胶稠度和淀粉晶体结构等指标上没有显著差异,而淀粉的热力学特性和淀粉黏滞性等指标存在显著的变化。说明PUL基因是影响稻米蒸煮品质的重要基因之一。来源于籼稻桂朝2号和粳稻苏御糯的PUL等位基因在功能上已经发生明显的分化。本研究中基于PUL基因序列差异设计的分子标记可以直接用于水稻品质的改良。 相似文献
49.
介绍了红蜡蚧的形态特征、生活习性、分布情况及危害风险性,重点综述了国内外红蜡蚧生物防治研究进展,分析了红蜡蚧生物防治方面存在的不足,并展望了今后红蜡蚧生物防治研究方向。 相似文献
50.