An elitist strategy genetic algorithm using simulated annealing algorithm as local search for facility layout design

A well-planned arrangement of manufacturing departments on a two-dimensional planar region considerably increases the efficiency of its production systems, which is termed facility layout problem (FLP). Conventional layout design approach often designs intercell layout (determining exact location of each department on shop floor area) and flow path layout design of material handling system (MHS) step by step in a sequential manner. This results in suboptimal solutions for FLP. In this paper, an integrated approach is adopted to design the intercell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing total material handling cost. Sequence pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently made by longest common subsequence (LCS) methodology. An elitist strategy genetic algorithm using simulated annealing (E-GASAA) as a local search mechanism is developed and tested with four test problem instances available in the literature. Elitist strategy is incorporated to enhance convergence characteristic of the proposed algorithm. It is found that the proposed E-GASAA is able to produce best solutions consistently for the test problem instance of different sizes within acceptable computational effort. In addition to that, we tried to reduce the computational load with the help of adopted LCS computation methodology and achieved a good improvement.     

飞机钣金零件自动排料系统的设计与开发

基于最低水平线搜索排样算法,探讨了飞机钣金零件自动排料系统的设计与开发。与传统的依靠人工经验试凑排料相比,该系统可自动完成排料,同时可运用人工干预将小零件填满空白区域,从而获得了利用率较高的飞机钣金零件排料图,降低了生产成本,提高了零件的生产效率。     

飞机钣金零件自动排料系统的设计与开发

基于最低水平线搜索排样算法,探讨了飞机钣金零件自动排料系统的设计与开发。与传统的依靠人工经验试凑排料相比,该系统可自动完成排料,同时可运用人工干预将小零件填满空白区域,从而获得了利用率较高的飞机钣金零件排料图,降低了生产成本,提高了零件的生产效率。     

平行轴齿轮传动系统的紧凑布置设计

平行轴齿轮传动系统的占用空间主要取决于轴横截面上的占用面积，减小轴横截面占用面积是其紧凑布置设计的重要组成部分，而其中的关键是如何实现啮合齿轮系凸包面积的计算方法。研究了啮合齿轮系凸包面积的计算模型，配合啮合和干涉约束的定义，给出了优化模型和算法实现。结果表明可以有效地缩小传动系统的占用空间，且对此类布置设计具有一定的通用性。     

Composite Planar Tolerance Allocation with Dimensional and Geometric Specifications

A new optimal approach for planar tolerance allocation is proposed in which dimensional and orientation geometric specifications are included. To deal with the increased complexity of planar tolerance analysis, a special relevance graph (SRG) is used to represent the relationships between manufactured elements and their size and tolerance information. In addition, the SRG is also applied for the geometric dimensions and tolerances. Using a suitable algorithm, planar tolerance chains that include geometric specifications can be generated automatically during process planning. Through a graph based analysis, stacks of tolerance zones are obtained. The resultant tolerance zone contains all of the composite links of the tolerance zones. The links are assigned according to the process capacities, which can be considered as constraints. A linear optimal model is established to solve the tolerance allocation problem. A practical example is used to demonstrate the feasibility and effectiveness of the proposed method.     

A genetic algorithm for the inter-cell layout and material handling system design

The traditional optimization processes for the cell system layout (CSL) and material handling system in cellular manufacturing systems (CMSs) were carried out sequentially and separately. The solutions obtained by this means can be far from the total optimum. In this paper, an integrated approach to the problem is proposed that attempts to design CSL and flow path structure simultaneously. The cells in question are assumed to be shape-fixed and have pre-determined pickup/delivery (P/D) stations. A sequence-pair based CSL-generating algorithm allows cells to be placed at any possible position on a continuous floor plan and leads to a corresponding feasible CSL. A grid graph for the CSL is accordingly constructed to provide possible flow paths for the layout. Then, the sum of the traveling distances, determined by the shortest path algorithm, is used to evaluate the CSL. These steps are embedded into a genetic algorithm (GA) that searches the solution space to obtain optimal layouts based on the contour distances between the P/D stations. Computational results demonstrate that the run time required to solve the test problems is quite acceptable given the long-term nature of facility layout decisions. Moreover, a comparison of the computational results with the existing methods indicates that the proposed approach is a viable alternative for effectively generating layout designs for CMS.     

A robust single row facility layout problem with fuzzy random variables

The facility layout problem is the optimal arrangement of facilities in the plant area. Based on layout configurations, there are several types of the facility layout problem. The single row facility layout problem (SRFLP) is one them in which facilities have to be placed along a line. Although there are exact approaches, based on the integer programming model for solving SRFLP, a huge number of variables and constraints should be used in this model. This paper presents a new exact method to SRFLP based on a new class of variables and an extended branch and bound method (B&B). First, the SRFLP is formulated by new decision variables. To solve it, a new branching scheme for B&B algorithm is presented. Subsequently, we introduce a fuzzy robust single row facility layout problem (FRSRFLP) and solve it by a real expected value method and a fuzzy stochastic chance-constrained programming based on possibility and necessity measures together with an extended B&B method. Furthermore, the proposed methods are applied for solving some benchmark problems to show their efficiency.     

Layout optimization of box girder with RBF-NNM-APSO algorithm

The layout optimization problem of complex box girder structure is solved with a new method RBF-NNM-APSO formed with the digital neural network model (NNM) of radial basis function (RBF) and adaptive particle swarm optimization (APSO) algorithm in this paper. The optimized surrogate model is proposed and applied to the configuration optimization of heavy-duty box girder of casting crane for improving the mechanical properties of the optimized object and expediting proceedings. First, the parametric command flow finite element numerical model of box girder is established. The RBF neural network is trained by constructing a mixed orthogonal experimental table of parameters, and the relationship between the design variables and the maximum stress and deformation is established. Subsequently, the trained RBF neural network design scheme is optimized by APSO algorithm. Finally, on the premise of not increasing the total mass, a new layout form of box girder is obtained.

     

Synthesis of a complete set of contracted graphs for planar non-fractionated simple-jointed kinematic chains with all possible DOFs

The contracted graph shows the primary topological structure of kinematic chains and is the foundation for constructing kinematic structures of mechanisms. In this paper, a fully-automatic method is proposed to synthesize a complete set of contracted graphs for planar non-fractionated simple-jointed kinematic chains with all possible degrees of freedom. First, based on the 4-parameter index and link assortment array, the relationships of link assortment arrays and non-fractionated contracted graphs for different types of kinematic chains are revealed. Then, the general steps to generate the adjacency matrices of contracted graphs from the synthesis equation set are given. Efficient methods to detect fractionated structures and isomorphism are also addressed. Finally, a human-machine interactive synthesis program is developed, and the complete list of both contracted graphs and valid contracted graphs for planar non-fractionated simple-jointed kinematic chains with up to 19 links and all possible degrees of freedom is presented for the first time.     

基于图论的高精度级进模跳步排样优化算法

跳步排样是高精度级进模ＣＡＤ中的重要组成部分。提出一种基于图论的跳步排样优化算法。利用工艺规则，通过起始关键点的获取，最少工步数的确定，到排样的优化，来保证级进模的工作精度。     

Rule- and PSO algorithm-based dynamic spatial rescheduling method for hull curved block construction

Due to no effective rescheduling method in hull curved block construction planning, existing scheduling planning can’t be applied in practical production effectively. Two-dimensional layout and dynamic attributes of block construction planning are considered to develop a spatial rescheduling method, which is based on the spatial points searching rule and the particle swarm optimization(PSO) algorithm. A dynamic spatial rescheduling method is proposed to solve the manufacturing problem of rush-order blocks. Through spatial rescheduling, the rescheduling start time, the current processing information set and rescheduling blocks set can be obtained automatically. By using and updating the data of these sets, the rescheduling method combines the PSO algorithm with the spatial points searching rule to determine the rescheduling start time and layout of the blocks. Three types of dynamic events, including rush-order block delay, existing block delay and existing block position changes, are used to address problems with different function goals by setting different function weights. Finally, simulations based on three types of rush-order block events are performed to validate this method, including single rush-order block, multi rush-order blocks at the same time and multi rush-order blocks at different times. The simulation results demonstrate that this method can solve the rush-order block problems in hull block construction and reduce the interference to the existing manufacturing schedule. The proposed research provides a new rescheduling method and helps instruct scheduler to make production planning in hull block construction.     

一种星空背景的运动补偿方法

运动背景补偿技术是提高运动星空背景下弱小目标检测精度的关键技术之一。本文提出了一种基于块匹配与质心提取法相结合的星空背景运动补偿技术。该方法在样本运动参数估计阶段直接剔除异常点;为了减少块匹配过程中每个待匹配位置的运算次数,保持块匹配的精度,又引入了连续排除算法,降低了计算复杂度。实验验证了该方法的有效性和优越性,证明了该方法能有效地提高目标的信噪比并且降低差分残余图像灰度均值。     

利用邻接矩阵的幂序列进行运动链和机构的同构判定

从同构的图论意义出发,提出了一个新的运动链结构不变量,进而提出了利用邻接矩阵的幂序列进行运动链同构判定的方法。它与现有的其他方法相比,具有直观、简便和显明图论依据的特点,且该方法不仅可以实现运动链的同构判定,而且可以成功地判定一般图的同构。在此基础上,本文最后给出了从同一运动链中识别出不同机构的两个方法。     

An algorithm of image segmentation for overlapping grain image

1Introduction Imagesegmentationisprimaryissueinim ageprocessing,atthesametimeitisprincipal probleminlowlevelvisionincomputervision field.Itisthekeytechnologytoprocessimage analysis,imagecomprehensionandimagedepic tionsuccessfully.Imagesegmentationmeans thatpendingprocessingimageisdividedinto severaldifferentareaswhichhavespecialmean ingandhavenotintersectantmutual.Theimage segmentationisinwideuse,butuptonow,thereisnotuniversalmethod,andthereisnot objectivecriterionwhichjudgethatifitissuc cessf…     

平面点集凸包图改进算法

对平面点集凸包图的构造算法进行了详细的研究 ,利用凸包图两条最基本的性质 ,通过做辅助线对已有算法进行改进并扩展其应用范围 ,实现了对平面点集任意形状包络图的构造     

混沌最小二乘法及其在机构近似综合中的应用

结合MATLAB6.5.1高级程序设计语言采用简单的最小二乘法迭代,并将非线性方程视为非线性的动力学系统,利用使系统产生混沌的Julia集的点求解方程的全实数解,而Julia集的点集用二周期逆像函数求得,再在其邻域内求解即可.运用该算法编写了MATLAB程序,对平面四杆机构近似综合问题进行了研究,从而找到了实现最大精确点时该问题的全部的解,为实际机构的设计提供了多种选择方案,为机构学设计提供了全新的方法.     

冲裁件优化排样算法的研究

通过对冲裁件优化排样问题的分析,提出了一种新的求解算法。其原理是先用等距水平线分割零件轮廓,得到一系列轮廓的特征点,然后利用其特性可快速确定零件轮廓在满足排样约束时的相互位置关系,通过与之匹配的高效算法可求得排样参数,获得最优排样方案。该算法除可完成一般的单排、双排、对头排等排样外,还可求解冲裁件嵌套排样问题,具有计算速度快、求解精度高、结果可靠等优点。     

Group-based multiple pipe routing method for aero-engine focusing on parallel layout

External pipe routing for aero-engine in limited three-dimensional space is a typical nondeterministic polynomial hard problem, where the parallel layout of pipes plays an important role in improving the utilization of layout space, facilitating pipe assembly, and maintenance. This paper presents an automatic multiple pipe routing method for aero-engine that focuses on parallel layout. The compressed visibility graph construction algorithm is proposed first to determine rapidly the rough path and interference relationship of the pipes to be routed. Based on these rough paths, the information of pipe grouping and sequencing are obtained according to the difference degree and interference degree, respectively. Subsequently, a coevolutionary improved differential evolution algorithm, which adopts the coevolutionary strategy, is used to solve multiple pipe layout optimization problem. By using this algorithm, pipes in the same group share the layout space information with one another, and the optimal layout solution of pipes in this group can be obtained in the same evolutionary progress. Furthermore, to eliminate the minor angle deviation of parallel pipes that would cause assembly stress in actual assembly, an accurate parallelization processing method based on the simulated annealing algorithm is proposed. Finally, the simulation results on an aero-engine demonstrate the feasibility and effectiveness of the proposed method.     

实用型冲压毛坯优化排样系统的研究与开发

针对冲压毛坯排样设计中的各种工程约束 ,结合生产实际 ,提出了 Auto CAD环境下实用毛坯优化排样系统的总体框架 ,并对系统开发中的难点——图形处理与排样算法 ,提出了解决图形干涉问题的毛坯图形等距放大算法 ,对排样参数计算算法进行了改进 ,克服了传统“一步平移算法”的缺陷     

STEP到VRML格式转化中实体三角剖分的快速算法

针对 STEP到 VRML 文件格式转换的需求 ,提出了一种改进的平面多连通域到单连通域的快速切分方法 ,并介绍一种适合 VRML 应用的任意二维平面域快速三角剖分算法 ,该算法生成的三角形较少