求解结构动力响应的算法比较

给出了用于求解结构动力响应的基于不协调时间有限元方法的算法公式。以及采用三次Ｈｅｒｍｉｔｅ插值多项式逼近状态变量。应用时间不连续的Ｇａｌｅｒｋｉｎ方法推导出的一个单步递推断算法公式。同时给出了与Ｎｅｗｍａｋ的梯形法则、ＨＨＴ－α等几种算法的数值比较。     

F165型发动机曲轴箱的强度与力学模型分析

用有限单元法对Ｆ１６５型发动机曲轴箱应力分布进行了计算和分析,并建立了曲轴箱的力学简化模型,通过测试验证了该模型的合理性。同时,对曲轴箱的薄弱环节提出了改进方案,从而提高了曲轴箱的工作性能和寿命。     

油缸未焊接部位的应力强度因子分析

应力强度因子K是断裂力学分析的一个重要内容,本文将油缸底盖与缸体间的未焊接部位视为内含圆筒形裂纹,在裂纹处采用了“1／4”弯曲奇异单元进行三维有限元分析,由裂纹面上的位移外推应力强度因子计算式,计算了油缸受内压和轴向载荷的K值。此研究为三维裂纹体的进一步分析打下了基础,是油缸优化设计关键的一步。其计算方法也可运用于类似结构的压力容器。     

济南近郊侧柏林内降水组成、降水再分配和悬浮颗粒沉积作用初报( 英文)

该文利用离子交换色谱 (HPIC)、ICP -MS和ICP -AES等方法 ,对济南近郊侧柏林内雨水和雪水样品的阳离子组成、阳离子含量、元素组成、元素含量、pH、电导率以及氮氧化物含量进行了测定 .对比分析发现 ,干径流、冠径流和空旷地雨水的电导率、元素组成、元素含量以及离子组成和离子含量呈现明显差异 .比如 ,干径流中钙离子的含量为 150 7mg·L- 1,而空旷地和冠径流的钙离子含量分别为 6 6 4mg·L- 1和 119mg·L- 1.干径流的电导率为 96 2 μs·cm- 1,空旷地的电导率则为 56 0 μs·cm- 1.雪水和雨水的结果比较表明 ,雪水的电导率、pH值、离子含量和元素含量都明显低于雨水 .比如 ,雪水的平均pH值为 4 8,而雨水的平均 pH值为 6 9.针叶叶面冲洗液的分析测定发现 ,有大量悬浮颗粒沉积于叶片表面 .钙、镁、钾、钠 4种阳离子的叶面沉积量达到 35 87kg·hm- 2 ,显示了侧柏林对悬浮颗粒的沉淀池作用     

Similar Boundary Element Method in Elastodynamics

For the boundary element method of elastodynamics, some properties of matrices are discussed in case of similar boundary elements and the similar boundary element method is presented. In a series of similar boundary elements, when the corresponding matrices of a boundary element are obtained, the ones of other boundary elements in the series can be obtained by proportion. Then the coefficient matrix of the last system of linear algebraic equations can be obtained by the method of superposition. Compared with the general boundary element method, the computing speed can be raised by the similar boundary element method given in this paper.     

Boundary Element Methods with Non-overlapping Doma in Decomposition for Elastodynamics

This paper presents the numerical implementation of boundary element method incorporated into a non overlapping domain decomposition method for solving the Navier equations of linear elastodynamics problems by Fourier transformation. Several examples are presented.     

Some Notes on the Variational Principles of Mechanics and Their Applications

This paper discusses the limitations of extension of classical Hamiltonian Principle to continuous systems, then reviews the new developments of operational theory in functional analysis and variational principles in non equilibrium thermodynamics based on field variation. Complementary dual variational principles including adjoined variational methods and generalized Green function method are bases of finite element analysis and boundary element analysis as well. From the point of view of physics, variational principles of macroscopic non equilibrium thermodynamic can be applied to all continuous mechanical systems. However, they have some limitations in application scope and remain to be developed.     

党参种子的离散元仿真参数标定与试验验证

为设计及优化党参机械化播种设备,提供基础仿真参数,本文对甘肃省种植的两种党参种子(渭党1号和甘党2号)通过试验法确定其基本物理参数(形状尺寸、质量密度、体积密度、千粒重、含水率)和接触力学参数(恢复系数、静摩擦系数);通过斜面滚动试验结合EDEM仿真,预测党参种子与ABS塑料板间的滚动摩擦系数;通过调整党参种子模型间的...     

Study on the variation of trace elements and oxidative stress in diaphragm of the diabetic rats

AIM:To investigate the relationship between trace elements and oxidative stress in diabetic diaphragm. METHODS: Contents of copper(Cu), manganese(Mn), zinc(Zn), iron(Fe),cadmium(Cd),chromium(Cr),cobalt(Co),molybdenum(Mo) and lithium(Li) in the alloxan-induced diabetic rat diaphragm muscles were measured by atomic absorption spectrophotometer, andtheir superoxide dismutase(SOD) activities and malondiadehyde(MDA) contents were detected. RESULTS: The contents of Cu, Zn, Cr and Li were lower and the Fe and Cd were higher in diabetic rat diaphragm muscles than that of the control group, but there were no significant differences in Mn, Co and Mo, between control and diabetic group. SOD activities decreased significantly and MDA contents increased significantly in diaphragm of diabetic rats as compared with the control group.In addition,in diabetic rats diaphragm, there was a positive correlation between Zn and SOD, and negative correlation between Zn and MDA, and Cd and SOD. CONCLUSION: Changes of the contents of Cu, Zn, Fe, Cd, Cr, Li and the increase of oxidative stress in diaphragm were found in the early diabetes, and Zn, Cd play an importment role in oxidative stress of diabetic diaphragm.     

重金属致植物矿质营养元素代谢异常的生理效应

重金属胁迫会导致植物体细胞的矿质营养元素缺乏、代谢过程紊乱,甚至可引起植物的死亡。综述了重金属导致植物体的某些矿质元素代谢异常的生理效应。