On fatigue damage accumulation and material degradation in composite materials

Phenomenological aspects of fatigue damage accumulation and material degredation in composite materials are examined. A damage variable is introduced to define phenomenologically the degree of damage, and a fatigue damage accumulation model is developed in which a power-law relationship between the rate of damage development, fatigue stress level, and the current level of damage is proposed. Evaluation of the model for a random short-fiber SMC (sheet moulding compounds) materials indicates good correlation between the present model and experimental results. The model can be used to assess the behavior of materials degradation and fatigue damage development in composite materials.     

Three-dimension flaw detection for the welded seams of pressure vessels

This article deals with the three-dimensional analysis of internal flaws occurring in the welded seams of pressure vessels so as to determine the real location of the defects. For this purpose stereoscopic twin radiographs were used. Owing to the fact that radiographs are taken with films in circular form whereas the films have to be assessed in the flat condition, it is necessary to establish the relevant analytic relation between the circular and the flat film. To this end some equations were first established for the image points of the assumed flat film and that of the circular film, leading to the relevant formulae for ascertaining the spacial point location of the defect in the welded seam. Defects of different locations bring about different photocouple-points. The real location of the defect can be determined through its coordinates, Z_A, X_A and Y_A obtained through film observation and calculation.     

基于模糊PID控制的InGaAs光电探测器的温控系统

InGaAs光电探测器性能的好坏与环境温度的变化密切相关,为了使探测器能有良好的工作特性,其工作环境温度必须具有高稳定度。温度控制系统以MSP430F149为控制核心,使用参数自整定的模糊PID控制算法,以脉宽调制的方式驱动半导体制冷器工作,实现对光电探测器的高精度温度控制。并对模糊PID控制的控制效果进行了SIMULINK仿真,最后在InGaAs光电探测器上进行了温度控制的实验。实验结果表明设计的温度控制系统可以达到±0.02℃的高精度控制,完全符合实际应用需要。     

渭河陕西段径流系列的一致性分析

水文资料是工程设计的基础资料,其资料的一致性直接影响工程设计结果的合理性。本文采用渭河陕西段林家村,咸阳,华县三站1951—2010年的年径流资料,定性分析、定量检验了其序列的一致性。结果表明：①径流序列的趋势、突变及参数等的变化并不足以表明其一致性的改变,需要进一步的检验;②通过定量检验表明：1969—1971年的突变并未通过显著性为0．05的一致性检验,而1991—1994年的突变却通过了显著性为0．05的一致性检验,说明渭河陕西段径流序列的一致性改变发生在1991—1994年间。     

和田河流域水环境污染及其防治

和田河流域属典型的大陆性干旱气候,作为干旱地区内陆河塔里木河的第三大支流,在新疆实行最严格的水资源管理制度的刚性约束条件下,保护水资源,解决流域水污染防治问题尤为至关重要。本文以和田河流域2007—2010年各时期水质监测数据为主要依据,对和田河流域水环境质量现状和未来进行了系统调查分析与预测评价,通过河流水体纳污能力的对比分析,表明尚可满足和田河水环境容量的纳污要求,不会对和田河水生态环境造成大的影响。最后提出了防治对策。     

复式断面明渠水流三维数值模拟

复式断面渠道水流流场结构比较复杂,本文用耦合式求解器对复式断面明渠水流的三维流场进行了模拟.采用交错网格,界面上的动量差值采用Roe格式,紊流数学模型选用雷诺应力模型.将计算结果与实验结果进行比较,两者的吻合度较好,从而验证了数学模型的可靠性,最后又对复式断面明渠横剖面上水流运动特性进行了分析.     

Shot peening simulation using discrete and finite element methods

Modeling shot peening process is very complex as it involves the interaction of metallic surfaces with a large number of shots of very small diameter. Conventionally such problems are solved using the finite element software (such as ABAQUS) to predict the stresses and strains. However, the number of shots involved and the number of elements required in a real-life components for a 100% coverage that lasts a considerable duration of peening make such an approach impracticable. Ideally, a method that is suitable for obtaining residual compressive stresses (RCS) and the amount of plastic deformations with the least computational effort seems a dire need.In this paper, an attempt has been made to address this issue by using the discrete element method (DEM) in combination with the finite element method (FEM) to obtain reasonably accurate predictions of the residual stresses and plastic strains. In the proposed approach, the spatial information of force versus time from the DEM simulation is utilized in the FE Model to solve the shot peening problem as a transient problem. The results show that the RCS distribution obtained closely matches with that of the computationally intensive direct FEM simulation. It has also been established, in this paper, that this method works well even in the situations where the robust unit cell approaches are found to be difficult to handle.     

阳离子染料匀染剂的合成与应用研究

本文对阳离子染料的上染特性曲线以及加入匀染剂TAN(1227)的上染特性曲线进行对比研究,合成了两种阳离子匀染剂十二烷基二甲基羟乙基氯化胺(LHAC)和十二烷基二甲基乙基溴化铵(LEAB),其匀染性能较为理想。另外,分别对阳离子匀染剂的复配物以及阳离子匀染剂与非离子匀染剂的复配物进行应用实验。结果表明,复配物的匀染性能都明显优于单独使用的阳离子匀染剂。从而为高性能阳离子匀染剂的研制和开发提供了依据。     

基于改进粒子群优化神经网络的电机故障诊断

为了更加准确快速地诊断出三相异步电动机运行过程中发生的各类故障,在采用小波包分析提取异步电机故障特征向量的基础上,提出了一种混沌动态权重粒子群算法(CDW-PSO)优化BP神经网络的故障诊断方法,构建电机的神经网络故障诊断模型,采用混沌动态权重粒子群算法优化神经网络的结构参数。实验分析表明,采用该方法用于电机故障诊断,诊断速度快、准确性高、可靠性好。     

基于径流侵蚀功率的流域次暴雨输沙模型研究——以岔巴沟流域为例

流域次暴雨侵蚀产沙模型研究是国内外土壤侵蚀研究的重点领域之一。提出了基于径流深和洪峰流量模数两个流域次暴雨洪水特征参数的径流侵蚀功率的概念;利用岔巴沟曹坪水文站1959至1990年间历年实测的次暴雨洪水径流泥沙资料,系统研究了该流域次暴雨径流侵蚀功率与流域输沙模数之间的相关关系,建立和验证了基于径流侵蚀功率的岔巴沟流域次暴雨输沙模型。结果表明,岔巴沟流域次暴雨径流侵蚀功率与流域输沙模数之间具有极显著的幂函数相关关系;模型验证期的次暴雨输沙模数模拟值与实测值之间具有较好的一致性。