摩托车传动副轴断裂分析

采用化学成分分析、断口分析、金相检验和硬度测定等方法,对断裂的某摩托车传动副轴进行了分析.结果表明,传动副轴的断裂是疲劳断裂.心部组织中的带状铁素体是引起断裂的主要原因.     

西方规划思路与体制对修改中国规划法的参考

规划法既要有理论基础,也要切合实际需要,既要考虑长远,又要照顾目前。本文综合西方(特别是英语世界)的经验,分西方规划思路传统和规划工作体制来讨论,配合中国国情,指出一些教训和启发。     

一种机器人多传感器联合系统的逻辑和代数分析方法

从信息单元处理流程和缓冲设计的角度探讨了机器人多传感器联合系统的逻辑和代数分析方法.在分析几种典型的多传感器的结构和缓冲设计模型的基础上,文章引入基于Petri Nets的逻辑表达方法和基于[Max, ]半环的代数分析方法.以自主式移动机器人的多传感器联合系统为背景,文章系统探讨了多传感器联合系统的逻辑和代数分析方法的具体应用.实验数据表明,这种多传感器联合系统的逻辑和代数分析方法可以满足自主式移动机器人系统分析和仿真的需要     

镁合金疲劳的研究进展

对近年来有关镁合金疲劳的研究进行了总结,考察了材料性质、腐蚀介质、高温环境等多种因素对镁合金疲劳性能的影响,并对裂纹萌生及扩展方式进行了分析,归纳了提高镁合金疲劳性能的方法--改善材料质量及表面强化处理或涂层处理,对镁合金疲劳性能的研究进行了展望.     

Transferability of Charpy Absorbed Energy to Fracture Toughness Based on Weibull Stress Criterion

The relationship between Charpy absorbed energy and the fracture toughness by means of the (crack tip opening displacement (CTOD)) method was analyzed based on the Weibull stress criterion. The Charpy absorbed energy and the fracture toughness were measured for the SN490B steel under the ductile-brittle transition temperature region. For the instrumented Charpy impact test, the curves between the loading point displacement and the load against time were recorded. The critical Weibull stress was taken as a fracture controlled parameter, and it could not be affected by the specimen configuration and the loading pattern based on the local approach. The parameters controlled brittle fracture are obtained from the Charpy absorbed energy results, then the fracture toughness for the compact tension (CT) specimen is predicted. It is found that the results predicted are in good agreement with the experimental. The fracture toughness could be evaluated by the Charpy absorbed energy, because the local approach give     

具有外部扰动分布时滞的不确定性Markov跳变系统的指数稳定性

本文讨论了更为广泛的具有分布型时滞,双线性马尔可夫过程跳变参数的不确定性系统。分析了该系统的鲁棒均方指数稳定性。设计了鲁棒反馈镇定控制器。基于LMI方法,得到了系统均方指数稳定的充分条件。在一定程度上推广了离散时滞下的相应系统的结果。     

Cracking energy estimation of ultra low-k package using novel prediction approach combined with global-local modeling technique

Interfacial crack/delamination, due to the presence of dissimilar material systems, is one of the major concerns of thermo-mechanical reliability for the development of next node technology in integrated circuits (IC) devices. The cracking energy results from many back end of line (BEOL) and packaging processes at various temperature differences is prone to drive the crack advance. To investigate the sensitivity of crack propagation in low-k dielectric materials, a robust estimation of J-integral approach combined with a rectangular path of integral contour is performed using finite element analysis (FEA). By means of the verification of 4-point bending test (4-PBT), excellent agreements are obtained as compared with the experimental data. Moreover, a multiscale modeling technique is proposed to resolve the difficulty of model construction as from bridge device level to packaging level. The sub-modeling procedures developed specifically for the impact prediction of interfacial crack in complicated Cu/low-k interconnects. The analytic results indicate the foregoing methodology is valuable to forecast the physical behavior and reliability of advanced IC devices in the nano scaled size. On the basis of the presented results in this research, an approximated criterion for determining the dimensions of sub-model is suggested and demonstrated as well.     

内建电场调控BaTiO_3-TiO_2光催化性能研究

采用水热法制备BaTiO_3-TiO_2复合材料,以罗丹明B为降解对象,研究BaTiO_3退火处理对BaTi O3-TiO_2复合材料光催化性能的影响。结果表明:BaTiO_3退火后所制备的BaTiO_3-TiO_2复合材料光催化活性比纯TiO_2、BaTiO_3以及BaTiO_3退火前的复合材料好。退火后BaTiO_3颗粒尺寸增大,四方相所占的比重增加,内建电场增大,提高复合材料界面处TiO_2光生载流子的分离率,表现出更优的光催化活性。     

Synthesis of the fluid machinery network in a circulating water system

Energy consumption of the fluid machinery network in a circulating water system takes up a large part of energy consumption in the process industry, so optimization on the network will enhance the economic and environmental performance of the industry. In this paper, a synthesis approach is proposed to obtain the optimal network structure. The effective height curves are used as tools to perform energy analysis, so that the potential placement of water turbines and auxiliary pumps can be determined with energy benefit. Then economic optimization is carried out, by the mathematical model with the total cost as the objective function, to identify the branches for water turbines and auxiliary pumps with economic benefit. In this way, the optimal fluid machinery network structure can be obtained. The results of case study indicate that the proposed synthesis approach to optimize the fluid machinery network will obtain more remarkable benefits on economy, compared to optimizing only the water turbine network or pump network. The results under different flowrates of circulating water reveal that using a water turbine to recover power or adding an auxiliary pump to save energy in branches are only suitable to the flowrate in a certain range.     

基于工况风险评估的叉车门架多工况拓扑优化

以某3T型内燃叉车的标准门架为例,实现了典型工况下门架系统的整体非线性有限元分析;基于工况数据（工作时长、结构应力及形变位移）,提出了工况风险评估方法及工况风险指标（RI）的概念;依据工况风险指标,提出了一种分配多工况拓扑优化权重系数的方法;采用折中规划法,以多工况下门架加权柔度最小为目标函数对门架结构进行拓扑优化;根据优化结果对门架结构进行改进设计,并进行了有限元分析。研究结果表明：风险评估法较传统平均分配法能得到更优的目标值;与原门架结构相比,新门架结构在3种典型工况下的最大应力分别减小10.05%、10.25%和1.58%,最大位移分别减小13.17%、12.93%和8.28%,质量减小7 kg。