三级圆柱齿轮传动的优化设计算法

以总中心距最小为目标的三级圆柱齿轮传动优化设计的数学模型包含有连续变量和离散变量,分析各设计变量之间的啮合关系和约束条件,并考虑各设计变量对优化目标的影响能力,通过在传动比和整体性约束等因素上解除各级传动间的耦合关系,将三级传动优化设计问题转换为传动比分配优化设计与单级齿轮传动优化设计问题的重复求解,并采用可行城的枚举优化算法实现单级齿轮传动优化设计,简化了求解运算.     

复杂工程系统的合理分解、灵敏度分析和优化设计

本文介绍一种适合于求解复杂工程系统的“分解——协调”优化方法。基本思想是把一个复杂工程系统分解成一系列容易求解的子系统,子系统之间的耦合由上下层之间的输入和输出量的灵敏度来协调,各子系统可根据自身的问题性质采用相应的优化方法来求解。该方法不仅适用于求解单学科的大型工程系统,而且适用于求解由多学科耦合的复杂工程系统,如果采用分散的计算机网络或并行处理器进行工作,这就与典型的工程设计组织形式相一致。该方法是在CAD环境下解决复杂工程系统优化设计问题的一种颇有前途的方法。     

大规模优化设计在HAJIF系统中的实现

针对分析模型精细化带来的大规模变量结构优化设计问题,深入系统地研究了大规模结构优化设计求解理论,并在HAJIF(航空结构强度分析与优化设计软件系统)中予以实现。HAJIF是一个十分有用的分析及优化软件,然而随着工程问题的日益庞大,该系统表现出设计规模受限的技术瓶颈,从而限制了它的广泛应用。本文通过一系列的理论改进突破了HAJIF系统中的一些关键问题,使得当前系统可处理设计变量达到10万量级。这些方法包括约束删除、约束区域化、变量处理、敏度分析等。     

混合不确定性鲁棒协同优化设计方法

为了改善鲁棒协同优化设计中约束函数鲁棒性评估的精确度,提出一种混合不确定性鲁棒协同优化设计方法.针对区间分布不确定性优化问题,该方法通过灵敏度分析方法修正子学科中的鲁棒约束函数,使不确定性因素不仅包括各输入变量的不确定性,还包括鲁棒协同优化求解过程中共享设计变量不一致带来的模型不确定性.数值算例的优化结果表明,混合不确定性鲁棒协同优化方法显著改善了约束函数鲁棒性评估的精确性.将该方法应用到一个卫星结构优化设计问题中,并采用自适应模拟退火算法求解,验证了该方法对复杂工程系统鲁棒优化设计问题的适用性.     

基于iSIGHT的多学科优化方法研究

多学科协同建模、仿真、优化是提高复杂产品设计质量的有效途径之一,针对在机构设计中过度考虑安全因素,导致材料浪费的问题,研究了在iSIGHT多学科优化平台上利用CAD／CAE学科软件搭建的装载机执行机构的多柔体虚拟样机模型。介绍了面向模型的多领域协同仿真技术及基于系统过程集成和命令文件解析的建模技术。应用多学科变量耦合优化算法有效地解决了子系统之间的耦合和并行优化设计。从结果分析中可以看出,用该方法有效地实现了装载机执行机构的轻量化设计。     

电子装备机电热多场耦合问题初探

介绍了普遍存在的多物理场场耦合问题.首先,给出了几个主要且常用物理场的数学描述,讨论了它们之间的场耦合关系,进而研究了多场耦合的建模问题.对电子装备中存在的多场耦合及其建模问题作了专门论述.其次,介绍了多场耦合问题的求解策略与方法,涉及到不同场网格之间的匹配、滑移及信息传递等问题.再者,阐述了多场耦合优化设计问题,给出了一种多场耦合问题的优化设计模型.     

高维多目标优化设计的灰色微粒群算法

提出了一种基于混合离散变量多目标优化设计求解方法,该方法应用灰色相对关联度将多目标优化问题转化为单目标优化问题,再用改进微粒群算法求解.开发了混合离散变量优化的灰色改进微粒群法程序.该方法能合理地处理优化设计中混合离散变量的取值问题,通过对标准微粒群算法改进,引入动态罚函数,算法具有很强的全局寻优能力.优化设计实例表明,该算法对优化设计问题的特性无特殊要求,具有较好的普适性,而且程序运行可靠,全局收敛能力强.     

流体动压轴承多目标优化设计的改进灰色微粒群算法

针对齿轮箱流体动压轴承多目标优化问题,提出了一种基于混合离散变量多目标优化设计求解方法,该方法应用灰色综合关联度将多目标优化问题转化为单目标优化问题,再用改进微粒群算法求解,开发了混合离散变量优化的灰色改进微粒群法程序.该方法能合理地处理优化设计中混合离散变量的取值问题,通过对标准微粒群算法改进,引入动态罚函数,构造一种新的适应函数,算法具有很强的全局寻优能力.优化设计实例表明,该算法对优化设计问题的特性无特殊要求,具有较好的普适性,而且程序运行可靠,全局收敛能力强.     

流体动压滑动轴承优化设计 (三)优化设计的数学模型

应用最优化方法求解机械工程中的设计问题,首先要根据设计问题的性质和特点将设计问题用数学的形式加以描述,即构造出优化设计问题的数学模型。然后选择适用的最优化方法对所构造的数学模型求解获得最佳方案。正确建立数学模型是优化设计的重要环节,它包括:设计变量的选择,目标函数的建立和约束条件的组成三个部分。鉴于机械设计中涉及的因素多、范围广、关系复杂,要写出描述设计问题的目标函数和约束条件的数学表达式,往往是有困难的。有时虽能写出表达式,其数学关系也非常复杂。流体动压滑动轴承优化设计数学模型的建立便是其中一例。     

基于DCCA-NSEn的系统耦合网络建模与评估

针对流程工业生产系统监测点多,各监测点间具有相关性的特点,提出了一种基于去趋势交叉分析-网络结构熵(detrended cross-correlation analysis-net structure entropy,简称DCCA-NSEn)的复杂机电系统多变量耦合网络建模与状态评估的方法。该方法利用DCCA算法计算多变量两两之间的相关性,构建反映多变量耦合关系的加权网络模型,对监测序列进行滑移求解,得到系统耦合关系网络动态演化模型。利用NSEn方法分析耦合关系网络的结构熵,根据熵随时间的变化趋势对复杂机电系统的服役演化状态进行评估。笔者选取某压缩机组的真实生产数据进行DCCA-NSEn方法验证,然后用耦合去趋势波动分析(coupling detrended fluctuation analysis,简称CDFA)方法对同一组生产数据进行多变量分析,对两方法的分析结果进行对比。结果表明:与DCCA方法相比,本方法具有多变量同时监测评估的优势;与同样是多变量分析的CDFA方法相比,本方法具有评估效果稳定,对系统的异常状态检测效果更明显的优势。     

一种可靠度计算的离散方法

机械系统的应力和强度往往是ｎ维随机变量的函数，可靠度难以求出。本文提出的离散方法，将大大减轻计算负担。通过蒙特卡罗模拟，证明这种方法在计算复杂系统的可靠度上，不仅简单，而且精确。     

电厂球磨机的模糊神经网络控制

广泛应用于火电厂的钢球磨煤机制粉系统是一典型的多变量非线性时变系统．各控制量之间存在着严重的耦合．这些因素使得基于常规PID方法设计的控制方案达不到控制作用。本文设计了一个模糊神经控制器并进行了仿真研究。并且用改进的粒子群优化算法对控制器的初值进行离线优化训练、最后的仿真结果表明优化后的模糊神经网络控制器对本文控制对象具有良好的控制性能，该控制方法可用于磨煤机制粉系统这类复杂过程的控制。     

超声电机多定子同步驱动技术的研究

研究多定子超声电机同步驱动技术,通过多定子同步驱动增加电机的驱动力(矩),解决目前单定子驱动电机输出功率不大的问题,并且以两个定子同步驱动为例,分别给出了采用分立元件、AVR以及DSP 3种器件设计驱动电路的方法,比较分析了各自的优缺点,并指出多定子同步驱动可有效提高电机运行的可靠性和稳定性,探讨了同步驱动技术今后的发展趋势。     

Study on the dynamic model and simulation of a flexible mechanical arm considering its random parameters

Randomness exists in engineering Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain So the behavior or response of the mechanical system is uncertain In this paper, the uncertain parameters are treated as random variables So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method Thus multibody dynamics simulation results can be obtained in statistics A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters (such as position, orientation, velocity, acceleration etc) of the key parts of a mechanical multibody system belong to their tolerance values A flexible mechanical arm with random parameters is studied in this paper The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm At the same time the end effector’s locating reliability is calculated with cncular tolerance area The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems     

Modelling and analysis of FMS productivity variables by ISM,SEM and GTMA approach

Productivity has often been cited as a key factor in a flexible manufacturing system (FMS) performance, and actions to increase it are said to improve profitability and the wage earning capacity of employees. Improving productivity is seen as a key issue for survival and success in the long term of a manufacturing system. The purpose of this paper is to make a model and analysis of the productivity variables of FMS. This study was performed by different approaches viz. interpretive structural modelling (ISM), structural equation modelling (SEM), graph theory and matrix approach (GTMA) and a cross-sectional survey within manufacturing firms in India. ISM has been used to develop a model of productivity variables, and then it has been analyzed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) are powerful statistical techniques. CFA is carried by SEM. EFA is applied to extract the factors in FMS by the statistical package for social sciences (SPSS 20) software and confirming these factors by CFA through analysis of moment structures (AMOS 20) software. The twenty productivity variables are identified through literature and four factors extracted, which involves the productivity of FMS. The four factors are people, quality, machine and flexibility. SEM using AMOS 20 was used to perform the first order four-factor structures. GTMA is a multiple attribute decision making (MADM) methodology used to find intensity/quantification of productivity variables in an organization. The FMS productivity index has purposed to intensify the factors which affect FMS.     

A systematic approach to manufacturing packaging logistics

Packaging is one of the most important activities in the distribution systems and supply chains. Nevertheless, it attracts little attention of people, especially in the manufacturing sector because packaging has been intensively used as a protective agent only. One of the prime factors that inhibit manufacturing efficiency and productivity is treating packaging activities as an individual task. In other words, traditional packaging is usually considered as a cost driven center rather than a value added component throughout the manufacturing and distribution processes. If we reconsider the packaging design in a systematic approach, it is easy to develop more cost effective solutions for manufacturing processing that can support handling and distribution as well as providing protection of the product. By the same token, it will bring additional values to a company because of the improvement in manufacturing and distribution efficiency. The aim of the paper is to review and reorganize the major functions and roles of the packaging played in the manufacturing and logistics system and suggest a methodology for a systematic approach to packaging logistics. The proposed approach is demonstrated through a case study. How to transform an existing packaging system to the proposed one is also suggested.     

Influence of nonlinear characteristics of electromagnet and normal force of a linear induction motor on a magnetically levitated vehicle

In the literature related to maglev vehicles, most studies have primarily discussed the trade-off between a levitation system and guideway smoothness, such as deflection and surface roughness, and the optimization of a levitation controller. A dynamic model integrated with a kinematic vehicle, electromagnetic suspension system, guideway profile, and levitation controller model has been widely used for this purpose. However, in addition to guideway smoothness and stiffness, the normal force of a Linear induction motor (LIM) that is installed in the same bogie frame and drives the maglev vehicle can be regarded as a disturbance element affecting a levitation system. In addition, a linear model of an electromagnetic force is usually used in linear approximations around the nominal equilibrium point, in spite of its nonlinear characteristics. In this study, to analyze the interaction between electromagnetic and normal forces of the LIM, a dynamic model coupled with the normal force calculated from finite element analysis was developed. In addition, to comparatively analyze levitation stability by considering the linear and nonlinear characteristics of electromagnets, the non-linear electromagnetic forces measured in the experiment are coupled to the dynamic model. From the simulation results, it was confirmed that although a slight increase in current was observed with the LIM model when compared to without the LIM model, it produced no adverse effect on levitation stability. In simulation, considering the non-linear characteristics of an electromagnet, it was confirmed that the nominal current of the linear model converged to a higher value than the designed nominal current when the vehicle was standing still, whereas the nominal current of the non-linear was similar to the designed one.     

转子碰摩的非线性运动特征及相关维数分析

在分析Ｊｅｆｆｃｏｔｔ转子碰摩模型的振动响应时,若不考虑静子振动,则碰摩转子系 统的运动具有高度非线性。本文探索了采用非线性和混沌信号的时域处理方法,通 过对碰摩转子系统响应的时间序列相空间重构及其相关维数估计,分析了碰摩转子 系统几种典型运动状态及其相应的相关维数。理论分析和计算结果表明,所估计的 相关维数在不同状态下有着显著的差别,可以对碰摩转子系统不同的状态进行分 类,对碰摩转子运动特性的研究提供了一种新的方法。     

扩展拉格朗日乘子粒子群算法解决工程优化问题

工程上很多优化问题,如容器设计、波纹管、板翅式换热器的结构优化设计等,皆为非线性约束优化设计问题,常采用惩罚函数法处理约束条件;为获得问题最优解,该方法需要合理确定初始惩罚因子,且需要动态惩罚因子无穷大。扩展拉格朗日乘子法是一种改进的惩罚函数法,可以克服惩罚函数法的不足,获得全局最优解,但目前对其研究和应用有限。对拉格朗日乘子法与粒子群算法相结合处理非线性约束问题进行研究,提出惩罚因子更新策略,确定扩展拉格朗日乘子粒子群算法合理的操作过程。标准测试函数结果显示：提出的方法及策略实现了扩展拉格朗日乘子粒子群算法解决非线性约束问题,并得到了问题的全局最优解;其在容器及波纹管系列优化设计中的应用进一步显示,提出的方法在处理非线性约束工程实际问题时,运行稳定可靠,可快捷获得问题的全局最优解或近似最优解。     

叶片泵常见故障分析

叶片泵结构简单、小巧，常用于机床的润滑液系统中。本文介绍了叶片泵的常见结构和工作原理。分析了叶片泵的常见故障。给出了维修实例，该维修实例验证了常见故障的分析和排除方法，为叶片泵常见故障的维修提供途径。