离心泵叶轮三维造型

离心泵叶轮是离心泵的最主要的部件,它的设计与造型至关重要。通过利用读入数据和、pro/e,对离心泵叶轮进行三维造型,为下一步的分析计算打下基础。     

带分流叶片的离心泵叶轮三维贴体网格生成

采用泊松方程进行带分流叶片的离心泵叶轮内三维贴体网格的自动生成 ,并通过源项控制来满足网格的正交性及调整网格疏密。计算时根据边界处网格线正交的控制角和控制距离的几何约束确定边界条件 ,利用分块粘接技术生成了带分流叶片离心泵叶轮内的三维分块结构化贴体网格 ,从而提高了流场流动分析中前处理环节的效率和精度 ,能使在湍流计算中广泛应用的壁面函数法的条件容易满足 ,并能使普遍采用的压力第二边界条件直接用于计算中 ,还能满足差分要求 ,减小离散误差。     

低比转数离心泵叶轮出口紊流流动结构分析

在叶轮内三维紊流流动数值计算的基础上，从介质能量的观点，分析了不同工况下低比转数离心泵叶轮出口处的紊流流动结构。数值计算采用SIMPLEC算法，在贴体坐标系下求解Navier—Stokes方程，紊流模型采用标准的κ—ε模型。计算结果表明，在叶轮的出口附近靠近吸力面一侧存在一个低能区，而压力面一侧能量相对较高。这与有关文献中所指出的离心风机的“射流—尾流”结构相对应。当偏离设计工况时，该低能区的范围和强度略有增加，相对应的叶轮效率也降低。计算结果与水泵在这些工况下的效率实验结果相一致，说明低能区的存在是影响低比转数离心泵效率的重要因素。     

用转轮内三元流动计算对泵叶轮进行改型设计

在有厚翼栅奇点解法的基础上，利用一种考虑叶片厚度影响的叶片式水力机械转轮内准三元流动新的分析方法、准确计算了泵叶轮叶片表面上的速度与压力变化分布规律，获得了许多水力性能评估参数；通过评价这些参数，对叶片型线进行了修改，获得了比较满意的结果。为叶轮的改型设计提供了一条较有价值的新途径。     

高速柴油机曲轴扭/弯/纵三维振动的试验研究

利用开发的轴系扭 /弯 /纵三维振动测试装置 ,对典型的直列 6缸车用柴油机进行了轴系扭 /弯 /纵三维振动的测试研究。通过对轴系振动的测试结果进行幅频特性分析以及相干函数分析 ,从试验研究的角度分析了轴系扭 /弯 /纵三维振动的相互影响的特点。同时 ,研究了轴系的三维振动与机体裙部振动的关系。     

云龙河拱坝施工过程的三维有限元

采用三维弹塑性非线性有限元法，对云龙河拱坝施工过程的实际浇筑、封拱和水库蓄水过程的坝体应力及变形进行了仿真分析，同时分析了施工过程的坝肩层间错层带的变形。计算结果表明施工过程的坝体变形较小，坝体有限元等效应力满足规范要求，坝肩层间错层带错动变形很小，说明大坝结构设计合理，坝肩无错动危险。计算成果为工程项目的实施提供了技术依据，同时对类似工程分析具有借鉴作用。     

惯性沉降分离室内三维定常气流流动数值计算

为了解气流在4ZTL-1800型割前摘脱稻（麦）联合收获机惯性沉降分离室内的运动规律，从流体力学和湍流理论出发，建立了气体运动微分方程式及k-ε湍流模型，并利用Fluent软件对惯性沉降分离室内三维定常气流进行了数值计算，得到了气体在惯性沉降分离室内的流动特征。根据其特征对分离室结构进行了改进设计，数值计算结果表明改进后惯性沉降分离室内的气流流场得到了改善。     

The Exploitation of Nematode-Responsive Plant Genes in Novel Nematode Control Methods

The molecular interactions between plants and sedentary nematodes are undergoing intense study, not only for reasons of fundamental research but also for the potential benefits to agriculture. The present technology allows the transformation of an increasing number of crop plants, providing new ways to introduce resistance against plant-parasitic nematodes. The ability of sedentary nematodes to induce specialized feeding sites in plant roots is one of the most fascinating aspects of this host–parasite interaction. Molecular approaches have been initiated to identify and characterize plant genes altered in expression after infection by sedentary nematodes. The results obtained indicate that many genes indeed become up-regulated upon nematode infection. Surprisingly, several so-called constitutive promoters that are normally used to achieve high expression in plant cells are completely ‘silenced’ in the feeding sites within days after nematode infection. Generally, there are two options available for the genetic engineering of nematode resistance: the synthesis of anti-nematode proteins or the localized production of a cytotoxic protein that interferes with the development of feeding cells. Nematode-induced promoters are very useful for the production by plants of sufficiently high levels of anti-nematode proteins at feeding sites. Alternatively, interfering with feeding-cell development is somewhat similar to the hypersensitive response evoked by nematodes in a naturally resistant plant. Here, destruction of specific plant cells can be achieved by the localized expression of a cytotoxin such as barnase, a potent ribonuclease. This approach, however, calls for a highly specific ‘non-leaky’ promoter, which is active only in the feeding cells. Another possibility is to use a two-component system, where the leakiness of the promoter in other tissues is counterbalanced by the constitutive expression of a neutralizing gene.