基于遗传算法的车间布局优化研究

针对某公司压力机装配车间设备布局问题,采用遗传算法进行优化设计。在其过程中首先建立数学模型,并设置约束条件、目标函数等因素。然后利用matlab软件将原车间布局作为初始种群,通过选择、交叉、变异等操作,运行成更合理的车间布局方案,优化方案证明了算法的实用性。     

基于自适应遗传算法的大型关重件车间布局优化

针对大型关重件生产车间的多行布局问题,建立了同时考虑物流费用与物流时间的多目标优化数学模型,运用了一种改进的自适应遗传算法,其交叉概率和变异概率可随群体的适应度自动改变,使算法避免陷入局部最优;加入精英保留策略,使每代中的最优个体都能够得到保留,避免交叉和变异操作遗失全局最优解.最后结合某船用曲轴车间实例,分别运用该算...     

基于虚拟现实的车间布局系统的研究

依据车间布局的最小物流费用原则,建立了布局优化的数学模型,并对该模型应用遗传算法进行求解.根据车间布局优化的特点,设计了混合编码的方法,并改进了选择算子、交叉算子和变异算子等遗传操作算子.最后给出了一个算法求解实例,并采用虚拟现实技术将计算结果形象地呈现出来.文中所提出的方法能够很好地解决车间设备布局问题.     

车间多行布局精准建模与多目标优化研究

基于车间布局总物料搬运成本最小和面积利用率最大的设计原则,同时考虑制造车间主干道、功能区横竖放置及自适应行距等因素,建立了生产车间多行直线布局的多目标优化精准数学模型,采用改进的多种群遗传算法(multiple population genetic algorithm, MPGA)进行求解。在求解过程中,采用移民算子联系种群,实现种群间的信息交换和协同进化,研究交叉和变异概率控制参数,以确保全局和局部搜索的精度。实例结果表明,该模型实用性强且求解算法稳定性好、收敛精度高。     

基于改进自适应遗传算法的柔性作业车间调度问题研究

为了克服遗传算法在解决柔性作业车间调度问题中收敛速度慢、易陷入局部最优的缺陷,根据柔性作业车间调度问题的特点,提出一种具有自适应交叉概率与变异概率的改进自适应遗传算法。将交叉概率与个体适应度值相关,将变异概率同时与个体适度值与进化代数相关,采用有效的编码、解码机制,引入精英保留策略。通过对两个基准问题进行仿真分析,验证了改进自适应遗传算法的有效性。     

车间多排设备布局问题的优化研究

在车间多排设备布局问题上往往存在限制条件多、设计方案不合理的情况。针对车间多排设备布局问题的特性,提出一种车间布局优化模型,并且利用遗传算法变异策略优势改进粒子群算法,使得设计方案更加合理。首先,将车间设备进行坐标化,建立了基于总物流成本最小的目标函数。经过综合分析,量化了各工序之间的物流关系。然后根据消防通道、设备占地与间距等非物流因素采用分级惩罚思想建立各种约束。此外,利用随机生存的初始种群,采用加入遗传算法的自适应变异策略的粒子群算法搜索最优车间布局。最后,通过一个案例研究了该模型的工作原理。与系统布置设计(Systematic Layout Planning, SLP)方法和遗传算法(Genetic Algorithm, GA)相比,该方法在解决多排设备布局问题效果更好。     

飞机结构件加工车间多层次式布局与优化研究

车间布局设计是一个具有非线性、NP-hard等特征的组合优化问题。结合飞机结构件生产多品种、小批量、短工序的特点,提出多层次式布局与优化策略,该策略从以下三层次进行:结合人机工程学,进行机床单元布局;根据机床数量以及型号进行功能区划分和功能区布局;以物流时间最短为目标进行总体布局,通过系统布置设计得出较优的初始解,利用遗传算法进行优化计算,得到最优布局方案。层次布局策略便于机床分区管理,减少直接布局的机床数量,更易获得令人满意的车间布局。最后,通过实例验证了多层次式布局与优化策略的有效性。     

基于差分进化与块结构邻域的作业车间调度优化

作业车间调度问题是一类非常重要的生产调度问题,具有广泛的工程应用背景.针对优化最大完成时间指标,研究通过交换或插入关键路径块结构中的工序产生可行解的方法,提出基于块结构的交换邻域和插入邻域.结合问题的结构特点和基本差分进化算法的原理,提出一种解决作业车间调度问题的离散差分进化算法.该算法采用基于操作的编码方式,设计了离散的变异算子和交叉算子,能够直接产生可行调度解.进而提出一种自适应的多邻域局部搜索算法,并将其嵌入离散差分进化算法中来改善优化质量;基于典型算例的仿真试验验证了所提算法的有效性和优越性.     

基于单级倒立摆的遗传神经网络控制研究

由于倒立摆是一个高阶次、非线性和自然不稳定系统,为了改善单级倒立摆的稳定性问题,提出一种改进遗传算法的RBF(径向基函数)神经网络控制方法.该方法以传统遗传算法为基础,通过对适应度值的自适应缩放、交叉率和变异率自适应调整等策略实现对RBF神经网络基函数参数和权值的优化.通过单级倒立摆仿真实验分析表明,虽然改进遗传算法的...     

基于改进遗传算法的PID参数优化在闪蒸罐压力控制中的应用

由于在加氢裂化过程中闪蒸罐压力控制存在非线性、大滞后等问题,运用常规比例-积分-微分(Proportion-IntegralDerivative,PID)控制效果较差,虽然传统遗传算法可以优化PID参数,提高控制精度,但是收敛速度慢,整定时间长,限制了其在闪蒸罐压力控制中的应用。针对以上问题,提出了一种通过改进遗传算法优化PID参数的新型方法,该方法以传统遗传算法为基础,通过对适应度值的自适应缩放、交叉率和变异率分别按Sigmoid函数和高斯分布函数自适应调整等策略来提高遗传算法的全局搜索能力和收敛速度,从而实现对PID控制参数的优化。仿真结果表明,用改进遗传算法优化后的闪蒸罐压力PID控制具有更好的自适应性和鲁棒性,使系统调节时间减少到86 s,超调量减少到0. 141 8%,有效地改善了系统的动、静态特性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.