Four-layer framework for combinatorial optimization problems domain

Four-layer framework for combinatorial optimization problems/models domain is suggested for applied problems structuring and solving: (1) basic combinatorial models and multicriteria decision making problems (e.g., clustering, knapsack problem, multiple choice problem, multicriteria ranking, assignment/allocation); (2) composite models/procedures (e.g., multicriteria combinatorial problems, morphological clique problem); (3) basic (standard) solving frameworks, e.g.: (i) Hierarchical Morphological Multicriteria Design (HMMD) (ranking, combinatorial synthesis based on morphological clique problem), (ii) multi-stage design (two-level HMMD), (iii) special multi-stage composite framework (clustering, assignment/location, multiple choice problem); and (4) domain-oriented solving frameworks, e.g.: (a) design of modular software, (b) design of test inputs for multi-function system testing, (c) combinatorial planning of medical treatment, (d) design and improvement of communication network topology, (e) multi-stage framework for information retrieval, (f) combinatorial evolution and forecasting of software, devices. The multi-layer approach covers ‘decision cycle’, i.e., problem statement, models, algorithms/procedures, solving schemes, decisions, decision analysis and improvement.     

System synthesis with morphological clique problem: fusion of subsystem evaluation decisions

The article focuses on the analysis and evaluation of composite systems on the basis of ordinal estimates for system components. This viewpoint corresponds to system synthesis as an integration (fusion) of local decisions into a global one. We examine hierarchical (tree-like) models for composite systems and consider the following: (1) traditional multi-criteria evaluation approaches; (2) morphological clique problem with special discrete spaces for evaluation of system excellence; and (3) generalization of morphological clique problem. The generalization of morphological clique problem is based on the following: (a) structure of compatibility between system components and its influence to problem complexity, (b) some kinds of compatibility for the components (e.g., asymmetric, negative), and (c) poset-like scales for system components (local decisions) and their aggregation into a scale for a resultant global decision. We consider four basic versions of poset-like scales for system components and several corresponding extended modified discrete spaces of system excellence. Numerical examples illustrate the material (e.g., scales, aggregation of scales, algorithms).     

A multi-application approach for synthesizing custom network-on-chips

Execution of multiple applications on Multi-Processor System-on-Chips (MPSoCs) significantly boosts performance and energy efficiency. Although various researchers have suggested Network-on-Chip (NoC) architectures for MPSoCs, the problem still needs more investigations for the case of multi-application MPSoCs. In this paper, we propose a fully automated synthesis flow in five steps for the design of custom NoC fabrics for multi-application MPSoCs. The steps include: preprocessing, core to router allocation, voltage island merging, floorplanning, and router to router connection. The proposed flow finds design solutions that satisfy the performance, bandwidth, and power constraints of all input applications. If the user decides, the proposed synthesis adds network-level reconfiguration to improve the efficiency of the obtained design solutions. With the reconfiguration option, the proposed flow comes up with adaptive NoC architectures that satisfy each application’s communication requirements while power-gate idle resources, e.g., router ports and links. If reconfiguration option is not set by the user, the proposed flow considers the top communication requirements among the applications in finding design solutions. We have used the proposed synthesis flow to design custom NoCs for several combined graphs of real-world applications and synthetic graphs. Results show that the reconfiguration option can save up to 98% in the energy-delay product (EDP) of the ultimate designs.

     

Cold-standby redundancy allocation problem with degrading components

Components in cold-standby state are usually assumed to be as good as new when they are activated. However, even in a standby environment, the components will suffer from performance degradation. This article presents a study of a redundancy allocation problem (RAP) for cold-standby systems with degrading components. The objective of the RAP is to determine an optimal design configuration of components to maximize system reliability subject to system resource constraints (e.g. cost, weight). As in most cases, it is not possible to obtain a closed-form expression for this problem, and hence, an approximated objective function is presented. A genetic algorithm with dual mutation is developed to solve such a constrained optimization problem. Finally, a numerical example is given to illustrate the proposed solution methodology.     

Automatic Reconfiguration of Petri Net Controllers for Reconfigurable Manufacturing Systems With an Improved Net Rewriting System-Based Approach

The advent of reconfigurable manufacturing systems (RMSs) has given rise to a challenging problem, i.e., how to reconfigure rapidly and validly a RMS supervisory controller in response to frequent changes in the manufacturing system configuration driven by fluctuating market. This paper presents an improved net rewriting system (INRS)-based method for automatic reconfiguration of Petri net (PN) supervisory controllers for RMS. We begin with presenting the INRS which overcomes the limitations of the net rewriting system and can dynamically change the structure of a PN without damaging its important behavioral properties. Based on INRS, a method for design reconfigurable PN controllers of RMS is introduced. Subsequently, we presented an INRS-based method for rapidly automatic reconfiguration of this class of PN controllers. In the reconfiguration method, changes in a RMS configuration can be formalized and act on an existing controller to make it reconfigure rapidly into a new one. Noticeably, no matter the design or reconfiguration, the expected behavioral properties of the resultant PN controllers are guaranteed. Thus, efforts for verification of the results can be avoided naturally. We also illustrate the reconfiguration of a PN controller for a reconfigurable manufacturing cell.     

Selecting and parameterising components using knowledge based configuration and a heuristic that learns and forgets

In this paper we suggest the use of knowledge based configuration in connection with CAD systems to enhance the ability of reusing models of CAD components and to automate solution processes especially of variational design problems. Configuration systems can support design engineers in choosing components and in checking consistency. We have investigated how configuration mechanisms can be applied to the design of engineering products and introduce our heuristic relevant knowledge first (RKF). This heuristic solves many of the problems which occur with configuration in engineering domains which continuously change, e.g. as a consequence of innovation. We conclude with the presentation of experiments performed with RKF.     

可重构制造系统监督控制器的自动重构

提出了基于改进的网重写系统(Improved net rewriting system, INRS)的可重构制造系统(Reconfigurable manufacturing systems, RMS) Petri网监督控制器的自动重构方法, 以快速适应由市场需求变化所引起的制造系统构形的频繁变化. INRS解决了网重写系统存在的问题, 可动态调整给定Petri网模型的结构而不改变其行为属性. 以集合和图的组合形式定义了RMS的构形, 并提出了基于INRS的一类模块化、可重构的Petri网控制器的设计方法. 针对这类Petri网控制器, 提出了基于INRS的自动重构方法. 方法可将RMS构形的变化转变为INRS的图重写规则, 并作用于当前Petri网控制器, 使其快速、自动地重构为所求的新控制器. 所提出的Petri网控制器的设计与重构方法, 均从理论上保证了结果的正确性, 免校验. 仿真研究验证了方法的有效性.     

Semi‐isometric Registration of Line Features for Flexible Fitting of Protein Structures

In this paper, we study a registration problem that is motivated by a practical biology problem – fitting protein structures to low‐re solution density maps. We consider registration between two sets of lines features (e.g., helices in the proteins) that have undergone not a single, but multiple isometric transformations (e.g., hinge‐motions). The problem is further complicated by the presence of symmetry in each set. We formulate the problem as a clique‐finding problem in a product graph, and propose a heuristic solution that includes a fast clique‐finding algorithm unique to the structure of this graph. When tested on a suite of real protein structures, the algorithm achieved high accuracy even for very large inputs containing hundreds of helices.     

Molecular solutions for minimum and exact cover problems in the tile assembly model

The tile assembly model is a novel biological computing model where information is encoded in DNA tiles. It is an efficient way to solve NP-complete problems due to its scalability and parallelism. In this paper, we apply the tile assembly model to solve the minimum and exact set cover problems, which are well-known NP-complete problems. To solve the minimum set cover problem, we design a MinSetCover system composed of three parts, i.e., the seed configuration subsystem, the nondeterministic choice subsystem, and the detection subsystem. Moreover, we improve the MinSetCover system and propose a MinExactSetCover system for solving the problem of exact cover by 3-sets. Finally we analyze the computation complexity and perform a simulation experiment to verify the effectiveness and correctness of the proposed systems.     

Rapid design and reconfiguration of Petri net models for reconfigurable manufacturing cells with improved net rewriting systems and activity diagrams

To respond rapidly to the highly volatile market, the emerging reconfigurable manufacturing systems (RMS) have brought forward two challenging issues, namely, how to build rapid a formal model of an initial manufacturing configuration and how to yield the goal model from the existing one along with manufacturing configuration changes (reconfiguration). As for the issues, we present in this paper a method for rapid design of Petri net (PN) formalized models of RMS, intended for supervisory control and logic control of RMS, as well as a method for automated reconfiguration of the models. Firstly, we present an improved net rewriting system (INRS) for dynamically operating net transformation, unlike its predecessor-net rewriting system, where the initial behavioral properties of the underlying PN rewritten can be preserved during the transformation. Subsequently, the paper proposes the three-phase method for rapid design of initial full PN models of reconfigurable manufacturing cells (RMCs). In this method, activity diagrams of Unified Modeling Languages version 2 (UML 2) are used to describe manufacturing configurations, firstly; then the sub-activity diagrams are transformed into PN sub-models; finally, the PN sub-models are automated synthesized into a full model by the approach of INRS. Further, we present a model reconfiguration method for this class of PN models. The method compares changes in activity diagrams of the existing and goal manufacturing configurations and converts them into net rewriting rules of INRS. By applying the rules obtained, the existing PN model can reconfigure into a new one for the goal manufacturing configuration. No matter the design method or the reconfiguration method, the behavioral properties of the obtained PN models, e.g., liveness, boundedness, or reversibility, can be guaranteed and thereby the efforts of verification can be avoided. Finally, rapid design of a PN model of a reconfigurable manufacturing cell, as well as its automated reconfiguration, is illustrated with the help of an example. The result indicates the validity of the methods.     

基于CAN总线的可重构SHM系统设计

针对结构健康监测(SHM)系统现场节点功能固化,不便于机动配置及后期维护等问题,提出一种基于CAN总线的可重构SHM系统架构,设计节点功能重构、网络结构重构以及资源分配重构等技术。以功能适配接口及嵌入式操作系统的软硬件协同实现节点功能重构,以自组织特征映射网实现网络结构重构的优先级聚类,以基于组件对象模型的上位监控软件实现资源的按需分配。利用该方法设计的系统具有灵活、高效和一定自主性等特点。     

Simultaneous design of membership functions and rule sets for fuzzycontrollers using genetic algorithms

This paper examines the applicability of genetic algorithms (GA's) in the simultaneous design of membership functions and rule sets for fuzzy logic controllers. Previous work using genetic algorithms has focused on the development of rule sets or high performance membership functions; however, the interdependence between these two components suggests a simultaneous design procedure would be a more appropriate methodology. When GA's have been used to develop both, it has been done serially, e.g., design the membership functions and then use them in the design of the rule set. This, however, means that the membership functions were optimized for the initial rule set and not the rule set designed subsequently. GA's are fully capable of creating complete fuzzy controllers given the equations of motion of the system, eliminating the need for human input in the design loop. This new method has been applied to two problems, a cart controller and a truck controller. Beyond the development of these controllers, we also examine the design of a robust controller for the cart problem and its ability to overcome faulty rules     

Enhanced mixed integer programming model for a transfer line design problem

Modular machining lines with multi-spindle workstations are considered. A multi-spindle head executes a set of operations. The problem of optimal design or reconfiguration of such lines is considered here. The set of all available spindle heads, operations executed by each spindle head, spindle head times and costs are assumed to be known. There are operations which can be executed by one of several candidate spindle heads, i.e., in different configuration with other operations. The problem consists in the choice of spindle heads from the given set and their assignment to workstations. The goal is to minimize the line cost while satisfying the precedence, inclusion and exclusion constraints. This problem is an extension of well known assembly line balancing and equipment selection problem. In our previous work, we proposed a MIP model which was significantly limited as to the size of the problems treated. In this paper, quite a few original approaches are suggested to improve the previous MIP model. The numerical tests reported show that the calculation time is drastically decreased, thereby expanding the model to larger and more realistic industrial problems.     

Group Search Optimizer: An Optimization Algorithm Inspired by Animal Searching Behavior

Nature-inspired optimization algorithms, notably evolutionary algorithms (EAs), have been widely used to solve various scientific and engineering problems because of to their simplicity and flexibility. Here we report a novel optimization algorithm, group search optimizer (GSO), which is inspired by animal behavior, especially animal searching behavior. The framework is mainly based on the producer-scrounger model, which assumes that group members search either for ldquofindingrdquo (producer) or for ldquojoiningrdquo (scrounger) opportunities. Based on this framework, concepts from animal searching behavior, e.g., animal scanning mechanisms, are employed metaphorically to design optimum searching strategies for solving continuous optimization problems. When tested against benchmark functions, in low and high dimensions, the GSO algorithm has competitive performance to other EAs in terms of accuracy and convergence speed, especially on high-dimensional multimodal problems. The GSO algorithm is also applied to train artificial neural networks. The promising results on three real-world benchmark problems show the applicability of GSO for problem solving.     

基于最大权团的曲面粗匹配算法

提出一种将曲面匹配问题转化为图论中的最大权团搜索问题、将最优的点对应关系用最大权团表示的曲面粗匹配算法,该算法分为点匹配、点对应图构造和最大权团生成等3个阶段.点匹配使用高曲率点和均匀采样点作为候选点,通过自旋图进行匹配计算,构造初始点对应集合;点对应图构造使用距离约束、法矢约束和唯一性约束构造图的边,并使用自旋图相关系数为顶点赋权值;最大权团生成使用基于分支限界的团搜索算法,从对应点图中提取出代表最优对应的最大权团.实验结果表明,文中算法稳定、有效、可扩展,能够进行部分曲面匹配,并且适用于欠特征曲面.     

A System to Define and Allocate Health Care Resources on a Territory to Improve the Life Quality of the Populations in Developing Countries

In this paper the health resource allocation problem is discussed. An object-oriented system is proposed and its implemented prototype is illustrated. It consists of two parts: a Geographical Information System, which is able to acquire and store both geographical and social-epidemiological information (including the resource distribution on that territory), and a Decision Support System, able to decide, using optimization algorithms, the new resource allocation in order to obtain a quasi-optimal solution for the cost/benefit ratio minimization problem, after having fixed the goal (e.g., the decrease of the incidence of a given disease) and constraints (e.g., a fixed budget, a given set of available resources, etc.). The object-oriented database which is part of the system can simulate and store different scenarios, depending on the different goals and constraints defined in input, by means of a user friendly interface.     

Optimal design of reconfigurable parallel machining systems

A reconfigurable machining system is usually a modularized system, and its configuration design concerns the selections of modules and the determination of geometric dimensions in some specific modules. All of its design perspectives from kinematics, dynamics, and control have to be taken into considerations simultaneously, and a multidisciplinary design optimization (MDO) tool is required to support the configuration design process. This paper presents a new MDO tool for reconfigurable machining systems, and it includes the following works: (i) the literatures on the computer-aided design of reconfigurable parallel machining systems have been reviewed with a conclusion that the multidisciplinary design optimization is essential, but no comprehensive design tool is available to reconfigurable parallel machining systems; (ii) a class of reconfigurable systems called reconfigurable tripod-based machining system has been introduced, its reconfiguration problem is identified, and the corresponding design criteria have been discussed; (iii) design analysis in all of the disciplines including kinematics, dynamics, and control have been taken into considerations, and design models have been developed to evaluate various design candidates; in particular, the innovative solutions to direct kinematics, stiffness analysis for the design configurations of tripod-based machines with a passive leg, and concise dynamic modelling have been provided; and (iv) A design optimization approach is proposed to determine the best solution from all possible configurations. Based on the works presented in this paper, a computer-aided design and control tool have been implemented to support the system reconfiguration design and control processes. Some issues relevant to the practical implementation have also been discussed.     

A systematic approach to a self-generating fuzzy rule-table forfunction approximation

In this paper, a systematic design is proposed to determine fuzzy system structure and learning its parameters, from a set of given training examples. In particular, two fundamental problems concerning fuzzy system modeling are addressed: 1) fuzzy rule parameter optimization and 2) the identification of system structure (i.e., the number of membership functions and fuzzy rules). A four-step approach to build a fuzzy system automatically is presented: Step 1 directly obtains the optimum fuzzy rules for a given membership function configuration. Step 2 optimizes the allocation of the membership functions and the conclusion of the rules, in order to achieve a better approximation. Step 3 determines a new and more suitable topology with the information derived from the approximation error distribution; it decides which variables should increase the number of membership functions. Finally, Step 4 determines which structure should be selected to approximate the function, from the possible configurations provided by the algorithm in the three previous steps. The results of applying this method to the problem of function approximation are presented and then compared with other methodologies proposed in the bibliography.     

Determining Attributes to Maximize Visibility of Objects

In recent years, there has been significant interest in the development of ranking functions and efficient top-k retrieval algorithms to help users in ad hoc search and retrieval in databases (e.g., buyers searching for products in a catalog). We introduce a complementary problem: How to guide a seller in selecting the best attributes of a new tuple (e.g., a new product) to highlight so that it stands out in the crowd of existing competitive products and is widely visible to the pool of potential buyers. We develop several formulations of this problem. Although the problems are NP-complete, we give several exact and approximation algorithms that work well in practice. One type of exact algorithms is based on Integer Programming (IP) formulations of the problems. Another class of exact methods is based on maximal frequent item set mining algorithms. The approximation algorithms are based on greedy heuristics. A detailed performance study illustrates the benefits of our methods on real and synthetic data.     

A sociotechnical method for designing work systems

The paper describes a new method for allocating work between and among humans and machines. The method consists of a series of stages, which cover how the overall work system should be organized and designed; how tasks within the work system should be allocated (human-human allocations); and how tasks involving the use of technology should be allocated (human-machine allocations). The method makes use of a series of decision criteria that allow end users to consider a range of factors relevant to function allocation, including aspects of job, organizational, and technological design. The method is described in detail using an example drawn from a workshop involving the redesign of a naval command and control (C2) subsystem. We also report preliminary details of the evaluation of the method, based on the views of participants at the workshop. A final section outlines the contribution of the work in terms of current theoretical developments within the domain of function allocation. The method has been applied to the domain of naval C2 systems; however, it is also designed for generic use within function allocation and sociotechnical work systems.