Optimization of a multi-Constant Work-in-Process semiconductor assembly and test factory based on performance evaluation

This paper considers a semiconductor assembly and test factory which is a three-segment-Constant Work-in-Process (CONWIP) system with overlapping machines. In the system, three types of carts circulate for meeting the physical requirements. The optimization problem in setting the suitable total Work-in-Process (WIP) level and the distribution in the three loops from the view of the trade-off between the throughput and the WIP level for the system is addressed. In the proposed model, the system is firstly modeled as a three-loop closed queue network and we propose an approximate method to evaluate the performance. The accuracy of the evaluation method was illustrated by numerical experiments, indicating that the method is fairly precise. Secondly, a Genetic Algorithm is designed to obtain near optimal results based on the performance evaluation. The semiconductor assembly and test system case as well as the application procedure were carried out in detail.     

An improved ant colony optimization algorithm for solving a complex combinatorial optimization problem

This paper presents an improved ant colony optimization algorithm (IACO) for solving mobile agent routing problem. The ants cooperate using an indirect form of communication mediated by pheromone trails of scent and find the best solution to their tasks guided by both information (exploitation) which has been acquired and search (exploration) of the new route. Therefore the premature convergence probability of the system is lower. The IACO can solve successfully the mobile agent routing problem, and this method has some excellent properties of robustness, self-adaptation, parallelism, and positive feedback process owing to introducing the genetic operator into this algorithm and modifying the global updating rules. The experimental results have demonstrated that IACO has much higher convergence speed than that of genetic algorithm (GA), simulated annealing (SA), and basic ant colony algorithm, and can jump over the region of the local minimum, and escape from the trap of a local minimum successfully and achieve the best solutions. Therefore the quality of the solution is improved, and the whole system robustness is enhanced. The algorithm has been successfully integrated into our simulated humanoid robot system which won the fourth place of RoboCup2008 World Competition. The results of the proposed algorithm are found to be satisfactory.     

基于MATLAB/VB的网络故障诊断软件设计

将VB调用Matlab的方法应用到基于神经网络的网络故障诊断系统软件的设计中;以VB编写诊断系统的主界面,利用ActiveX技术调用Matlab神经网络工具箱完成对网络故障的诊断,将两者的优势有机结合,从而缩短了程序开发周期,减少了程序员的工作量;该软件具有良好人机交互界面,便于网管人员的学习和掌握,且实例验证表明利用VB调用Matlab方法开发的网络故障诊断系统,其诊断结果可靠,能够满足网络实时故障诊断的要求.     

我国仪器仪表与测量控制科技的发展

从战略高度,深刻全面地论述了仪器仪表与测量控制在当今社会的重要地位和作用、我国仪器仪表与测量控制的基本概况以及今后发展的趋势和特点,特别指出我国工业自动化仪表与控制系统以及科学仪器未来发展的关注点.同时,阐述了我国仪器仪表与测量控制近年来的重大进展,指明了我国仪器仪表与测量控制自主创新发展的方向.     

Formation Control and Tracking for Co-operative Robots with Non-holonomic Constraints

This paper mainly addresses formation control problem of non-holonomic systems in an optimized manner. Instead of using linearization to solve this problem approximately, we designed control laws with guaranteed global convergence by leveraging nonlinear transformations. Under this nonlinear transformation, consensus of non-holonomic robots can be converted into a stabilization problem, to which optimal treatment applies. This concept is then extended to the formation control and tracking problem for a team of robots following leader-follower strategy. A trajectory generator prescribes the feasible motion of virtual reference robot, a decentralized control law is used for each robot to track the reference while maintaining the formation. The asymptotic convergence of follower robots to the position and orientation of the reference robot is ensured using the Lyapunov function which is also generated using chained form differential equations. In order to witness the efficacy of the scheme, simulations results are presented for Unicycle and Car-like robots.     

Sensitivity analysis of important parameters affecting contact pressure between a respirator and a headform

Respirator comfort and fit are two important parameters for respirator design, usage, and standard development. The contact pressure (as measured between a respirator and the wearer) plays an important role in comfort and fit. This work attempts to investigate the contact mechanism and factors that affect the contact pressure. This paper focuses on mechanical factors such as strap tension, strap orientation, strap location, friction, and seal material. A finite element (FE) model-based method was developed to assess the contact pressure. The FE models for both the headform and the respirator have multiple layers. The headform is a medium size headform developed by the National Institute for Occupational Safety and Health (NIOSH) and the respirator is an MSA Affinity Ultra respirator. The results show that the positive Z directional force of strap tension that forces the respirator to move towards the headform is the most important parameter for measuring pressure distribution. Other factors such as strap orientation, friction, strap location, and softness of the seal material were found to affect the contact pressure distribution in this study. Strap orientation and friction coefficient have no significant effect on maximum pressure and maximum shear stress. The dispersive strap location increased the contact pressure on the nose-bridge area of the wearer, while concentrated location had no considerable effect on contact pressure. A softer seal material causes larger deformations and transfers the location of the maximum pressure from the nose-bridge to the tip of the nose.

Relevance to industry

This study investigates the effect of important parameters on contact pressure between a respirator and a headform. The sensitivity analysis can provide insights of the interaction between a respirator and a headform. The findings are critical to respirator designers, users, and standard developers to ensure maximal respirator fit and comfort.     

基于Web的企业内部质量审核系统设计与实现

通过对基于Ｗｅｂ的企业内部质量审核系统的设计和实现,研究基于Ｗｅｂ的应用系统开发中的系统分析方法、实现环境和开发工具等。     

软件可靠性及其评估

介绍了软件可靠性问题的来源,阐述了软件可靠性的定义、软件的失效机理、及软件可靠性与硬件可靠性间的差异,并提出了基于模糊数算术运算的软件可靠性估计方法。     

长期施用含氮化肥对大豆生育及养分吸收的影响

从1984年起,在沈阳农业大学棕壤上没有氮化肥长期定位试验。结果表明,长期施用含氯化肥在大豆整个生育期内可促进株高、茎粗、根系等地上部及地下部的生长,氯对大豆氮、磷养分的吸收无明显影响,对钾的吸收有 促进作用。