电子设备中吸波材料位置与尺寸的优化设计初探

为提高电子设备的电磁屏蔽能力,在其内部加贴吸波材料是一条有效途径.在材料等本身参数一定的情况下,贴装位置与尺寸对屏蔽效果有明显影响,特别对复杂结构,需要同时考虑对散热的影响.文中提出了一种优化设计模型,通过某实际机箱的数值优化,说明了模型与方法的有效性.     

Efficient automatic polishing process with a new compliant abrasive tool

In this paper, an efficient polishing process is proposed for precision polishing tasks using a new compliant abrasive tool. The polishing process is conducted by a force-controllable five-axes robot. The polishing process comprises many steps using different abrasive grain sizes. For each process step, an optimal set of polishing parameters that can efficiently reduce surface roughness is determined by the Taguchi method. The relation between the surface roughness and the polishing efficiency for each set of optimal parameters can be fitted as an R–E curve. The efficiency of a polishing step decreases with the number of polishing cycles and the surface roughness reduces to an asymptote value. The automatic polishing scheduling is fulfilled by switching to a more efficient choice among these R–E curves until the desired surface roughness is reached.     

铰链式高冲击微加速度传感器封装的有限元模拟

给出了一种新型铰链式高冲击微加速度传感器实际封装结构的有限元模拟分析。首先分析了封装前铰链式加速度传感器的振型,然后分析了封装结构在无灌封和五种不同灌封材料下的前十阶模态频率特性。灌封胶弹性模量对封装后加速度传感器整体结构的振动模态有一定的影响,封装结构同一振型的模态频率随着灌封胶弹性模量的增大而增大,但是灌封胶弹性模量很小时(E≤1 GPa)会导致加速度传感器信号失真。模拟结果表明,可以选择弹性模量足够高的材料(E>9 GPa)作为高冲击加速度传感器的灌封材料。     

An efficient algorithm for scheduling jobs on a machine with periodic maintenance

As machine maintenance is required in many industries, it is usually arranged in a planned schedule. In this paper, we discuss a scheduling problem where periodic maintenance and jobs are scheduled on a regular basis. In our research, a periodic maintenance sequence consists of several maintenance periods and each maintenance period is scheduled after a fixed time interval. The objective is to minimize the total flow time and the maximum tardiness. A heuristic that utilizes the theorem is proposed to solve the problem by providing a small set of efficient sequences. A decision-maker may choose one of the sequences according to his preference. We also propose a branch-and-bound algorithm is to find the optimal sequence. Computational results show that the presented heuristic is highly accurate and efficient.     

机械手臂结构优化设计

机械手臂的设计是目前机器人科学研究的一个热点。这里考虑手臂的抓重、材料和运动速度,对其进行优化设计。建立了优化设计的数学模型,使用MATLAB软件分析目标函数的性态并设计变量的可行域,求得机械手臂最优尺寸。在满足条件的情况下,使手臂质量最小,证明了该设计可以满足预设动作要求。     

Parallel line job shop scheduling using genetic algorithm

Parallel line job shop scheduling involves the optimal allocation and scheduling of jobs in multiple processing lines. Each job is allocated to a particular line and is processed to completion in that line. Also, all jobs allocated to a line are processed in a particular order. The objective of this paper is to find the optimal allocation of jobs to lines and also the optimal order of jobs processed in each line based on individual processing times and set up times. The optimal schedule gives the minimum makespan for the completion of all jobs. The optimization technique used is genetic algorithm.     

A simulated annealing algorithm to find approximate Pareto optimal solutions for the multi-objective facility layout problem

In this article, we consider the facility layout problem which combines the objective of minimization of the total material handling cost and the maximization of total closeness rating scores. Multi-objective optimization is the way to consider the two objectives at the same time. A simulated annealing (SA) algorithm is proposed to find the non-dominated solution (Pareto optimal) set approximately for the multi-objective facility layout problem we tackle. The Pareto optimal sets generated by the proposed algorithm was compared with the solutions of the previous algorithms for multi-objective facility layout problem. The results showed that the approximate Pareto optimal sets we have found include almost all the previously obtained results and many more approximate Pareto optimal solutions.     

快开盲板新型头盖的应力分析及优化设计

针对快开盲板的一种新型的变厚度头盖 ,运用有限元应力分析寻求出最大应力点 ,并对其关键尺寸DN和R的关系进行优化 ,得出其R与DN的最佳关系点 ,得出这一最优关系下的最大应力近似计算关系 ,为这一新型盲板头盖的应用打下基础。     

Scheduling of jobs and maintenance in a textile company

In this paper we consider a periodic maintenance scheduling problem in a textile company. In our research, a periodic maintenance schedule consists of several maintenance periods and each maintenance period is scheduled after a periodic time interval. The purpose of this paper is to find a schedule that minimizes the maximum tardiness subject to periodic maintenance and nonresumable jobs. An efficient heuristic is developed to provide the near optimal schedule for the problem. A branch-and-bound algorithm is also proposed to find the optimal schedule. Some important theorems associated with the problem are implemented in the algorithm. Computational results show that the proposed heuristic is highly accurate and efficient.     

Optimal positioning of irregular shapes in stamping die strip

The nesting of two-dimensional shapes is a common problem, where raw material has to be economically cut. As for the single-pass single-row strip layout, several algorithms, based on established methods, have been proposed. Moreover, it should be noticed that the optimum layout should also consider a few constraints, like grain orientation for subsequent forming operation, correct bridge width, and the commercial roll of metal width in order to make solutions applicable in real industrial environments. Most of the procedures until now shown in literature are quite complex and often ignore these real constraints. They usually make use of sliding techniques and are not able to effectively work with relatively multiple-connected figures. In particular, most of the different proposed procedures are based on the No Fit Polygon (NFP) computation of non-convex polygons, which often generates holes. This work is a proposal for a more efficient method, which can be used in heuristic procedures. In order to overcome some faults of most of the former methods presented in literature, in this paper a new geometric entity called ??No Fit Path?? (NFPh) of non-convex polygons is applied. It allows researchers to find solutions of nesting problems even when there are NFP faults due to degenerate solutions. Moreover, the No Fit Path allows researchers to easily read, modify, or share their results, overcoming all those problems arising from the usual large amount of information and from the different origins and formats of the obtained data. Given two non-convex polygons, the algorithm is able to calculate their NFPh very quickly and without any approximation by a polygon clipping method. In this paper a totally automated procedure has been developed. This procedure firstly obtains the ??No Fit Path?? (NFPh); secondly, between all the existing positions on the NFPh, the algorithm searches the optimal one, minimizing the global waste. The proposed approach also allows designers to set an optimal orientation of the shapes on the roll of metal, taking account of the grain orientation in order to obtain the best mechanical characteristics for the cut pieces.     

3D打印中的模型分割与打包

为了提高3D打印技术中三维模型的打印效率,减少打印材料耗费,缩短打印时间,提出了一种全局最优的模型分割与打包算法。首先,将给定模型分割为若干金字塔形状的分块。然后利用一种改进的禁忌搜索算法寻找最优打包方案,尽可能地减少支撑材料的体积,根据分块体积给出利于全局优化的初始解,并通过控制邻域生成规则以及候选解集,使得搜索更加高效并大幅提高寻优速度。最后,将打印成型的各部件拼合成整体。实验结果表明:生成的打包方案节省了14%~38%的打印时间,节省了21%-46%的打印材料。该方法模型分割产生的分块个数少、打包高效合理,不仅有效地提高打印效率,还减少了打印时间和支撑材料消耗。     

基于多目标优化的扁挤压筒结构设计

在组合式扁挤压筒的结构尺寸设计中，为确保挤压筒最佳工作性能的同时，最大程度地减少过盈装配后内腔产生的变形，提出了多目标优化的概念。结合有限元模拟技术和BP神经网络方法，建立了变过盈量下三层组合式扁挤压筒结构尺寸与各层等效应力分布、内腔位移之间的非线性映射模型，采用多目标遗传算法对其进行优化。优化时，采用了向量评价法、最佳个体保存策略和小生境技术，得到了均匀分布的Pareto最优解，根据定义的满意度函数，选出了最终的满意解。结果表明，在该满意解下，扁挤压筒既实现了等强度设计，又保证了内腔的尺寸精度。     

Product Mix Optimization for Semiconductor Manufacturing Based on AHP and ANP Analysis

In a competitive market, a company needs to utilize its available capacity efficiently in order to acquire high profit. The purpose of this paper is to present effective approaches to find a set of product mix optimal for the company to achieve the optimal manufacturing. Analytic hierarchy process (AHP) and analytic network process (ANP) approaches are taken to analyse multiple process inputs and outputs, incorporating experts’ opinion on their priority of importance, to obtain optimal product mixes for semiconductor production. The results provide guidance to the fabricator regarding strategies for accepting orders to maximize the manufacturing efficiency and the profit, while simultaneously considering other important input and output factors for maintaining manufacturing smoothness.     

Topology optimization of a PCB substrate considering mechanical constraints and heat conductivity

A material mixing method was suggested to obtain an optimal topology for a multiple material structure with multiple thermal criteria, based on Evolutionary Structural Optimization (ESO). To examine the validity of the method, it was applied to a printed circuit board (PCB) substrate. The overall efficiency of material usage in a PCB substrate was measured in terms of the combination of thermal stress and heat flux density by using a combination strategy with weighting factors. A Pareto optimal topology solution having multiple thermal criteria was obtained. The effects of weighting factors for multiple thermal criteria as well as mechanical boundary conditions on optimal topologies were investigated. It was found that as the weighting factor for heat flux density becomes larger, the sizes of holes at the center portion become larger in order to dissipate thermal energy much more efficiently. It was also found that as the magnitudes of the heat conduction are getting larger, a similar tendency of the optimal topologies is obtained to the above. The thermal stress on the clamped four sides is larger than that on the two sides clamped. It is verified that the suggested material mixing method works very well for topology optimization of a PCB substrate for various mechanical boundary conditions with multiple thermal criteria.     

可靠性约束下的包装生产线运行参数优化

针对包装生产线运行参数的选择与优化问题进行了研究,根据包装生产线的结构特点,构建了各耦合单元的可靠性与运行参数之间的映射关系,建立了可靠性约束下的包装生产线运行参数优化模型。以订单周期内包装生产线的有效运行速度为优化目标,采用自适应遗传算法求解最佳运行速度。实验结果表明,所提出的可靠性建模方法对研究可靠性约束下包装生产线的运行参数优化问题是有效和实用的。     

功率分流混合电动车辆动力系工作优化(Ⅱ)

本文讨论如何处理好控制混合电动车辆的动力系,基于多目标优化推荐了一个功率分流混合电动车辆的优化工作。开发了一个准静态动力系模型,探索了整个工作选择的空间,以便找到一个可达到的最佳工作可选择的组合。采用这种概念,开发了二种模拟:模拟一是基于等量燃油消耗量最小,其二是采用动态优化。按结果的分析和比较,按最小的等量燃油消耗找出几乎最高的效率,作为按优化控制模拟求得理论上最大的性能。结果除了在高动力负荷工况外不表示显著的差异。根据这个分析,同时为车辆在纯电动车辆工作模式推荐了一个临界值。     

功率分流混合电动车辆动力系工作优化

本文讨论如何处理好控制混合电动车辆的动力系,基于多目标优化推荐了一个功率分流混合电动车辆的优化工作.开发了一个准静态动力系模型,探索了整个工作选择的空间,以便找到一个可达到的最佳工作可选择的组合.采用这种概念,开发了二种模拟:模拟一是基于等量燃油消耗量最小,其二是采用动态优化.按结果的分析和比较,按最小的等量燃油消耗找出几乎最高的效率,作为按优化控制模拟求得理论上最大的性能.结果除了在高动力负荷工况外不表示显著的差异.根据这个分析,同时为车辆在纯电动车辆工作模式推荐了一个临界值.     

基于非线性有限元的箱口密封设计

采用非线性有限元分析软件MARC,建立了包装箱箱口密封有限元模型,分析了橡胶圈结构形式和材料硬度对箱口密封效果的影响。分析认为接触面积大小是决定这类包装箱密封特性的主要因素,因此选用材料较软及凸台与橡胶圈接触面积较大的结构方案有利于密封效果的提高。     

应用模糊综合评判实现电池自动涂膜机的创新设计

提出了碱锰电池自动涂膜机的设计原理及设计方案，针对碱锰电池自动涂膜机的多种设计方案，运用二级模糊综合评判方法建立评判模型，对自动涂膜机各因素集和备择集进行了综合评价，最终获得了最优解，体现了模糊综合评判法的有效性，从而对自动涂膜机进行了创新设计。在此基础上，制造出功能最优的自动涂膜机，应用于生产上料平稳，工作正常，故障率低。各指标达到设计要求。