Some chain visibility problems in a simple polygon

In this paper, the notions of convex chain visibility and reflex chain visibility of a simple polygonP are introduced, and some optimal algorithms concerned with convex- and reflex-chain visibility problems are described. For a convex-chain visibility problem, two linear-time algorithms are exhibited for determining whether or notP is visible from a given convex chain; one is the turn-checking approach and the other is the decomposition approach based on checking edge visibilities. We also present a linear-time algorithm for finding, if any, all maximal convex chains of a given polygonP from whichP is visible, where a maximal convex chain is a convex chain which does not properly include any other convex chains. It can be made by showing that there can be at most four visible maximal convex chains inP with an empty kernel. By similar arguments, we show that the same problems for reflex chain visibility can be easily solved in linear time.     

A local evaluation of vectorized documents by means of polygon assignments and matching

This paper presents a benchmark for evaluating the raster to vector conversion systems. The benchmark is designed for evaluating the performance of graphics recognition systems on images that contain polygons (solid) within the images. Our contribution is two-fold, an object mapping algorithm to spatially locate errors within the drawing and then a cycle graph matching distance that indicates the accuracy of the polygonal approximation. The performance incorporates many aspects and factors based on uniform units while the method remains non-rigid (thresholdless). This benchmark gives a scientific comparison at polygon level of coherency and uses practical performance evaluation methods that can be applied to complete polygonization systems. A system dedicated to cadastral map vectorization was evaluated under this benchmark and its performance results are presented in this paper. By stress testing a given system, we demonstrate that our protocol can reveal strengths and weaknesses of a system. The behavior of our set of indices was analyzed when increasing image degradation. We hope that this benchmark will help assessing the state of the art in graphics recognition and current vectorization technologies.     

多式综合公交系统线网布局优化模型及仿真

结合综合公交中各式公交的适应性和服务阈值,兼顾出行者不同出行目的时间价值敏感性,建立了综合公交系统线网布局双层优化模型,上层是0-1数学规划模型,下层是用户平衡分配模型。同时,基于改进的IOA进行优化求解,克服了传统单式线网优化层次化不显著的缺陷,提高了布局优化过程求解效率。算例仿真结果表明:综合公交系统需求多样性在客观上决定综合公交系统线网的多元性和层次性,线网布局优化需考虑不同出行目的的时间价值特性,以提升系统速度和能力的连续性。同时,基于改进的IOA在多式综合公交系统线网布局优化的巨大搜索空间中可靠便捷地找到近似最优解,提高了计算效率。     

Interior layout topology optimization of a reactive muffler

This article presents a material distribution method that is tailored to the interior design of reactive mufflers. Such devices are typically acoustically small, except in the length direction, and their interior consists of a combination of pipes, expansions, contractions, and Helmholtz resonators. In order to design the interior layout using material distribution optimization, it is necessary to be able to resolve thin sound-hard materials as well as thin sheets with a given acoustic impedance, such as perforated plates, and manage small channels to Helmholtz resonators. We develop a method that uses an anisotropic design filter in combination with a fine mesh in order to control the minimum thickness separately in different directions. A two-stage post processing procedure is used to control openings to resonators, and embedded thin impedance surfaces are modeled by a mortar-element method. Numerical results demonstrate that the approach can produce mufflers with high transmission loss for a broad range of frequencies. The optimized mufflers include components that resemble combinations of expansion chambers, cylindrical pipes, and Helmholtz resonators.     

Dynamic modeling and redundant force optimization of a 2-DOF parallel kinematic machine with kinematic redundancy

High precision is still one of the challenges when parallel kinematic machines are applied to advanced equipment. In this paper, a novel planar 2-DOF parallel kinematic machine with kinematic redundancy is proposed and a method for redundant force optimization is presented to improve the precision of the machine. The inverse kinematics is derived, and the dynamic model is modeled with the Newton–Euler method. The deformations of the kinematic chains are calculated and their relationship with kinematic error of the machine is established. Then the size and direction of the redundant force acting on the platform are optimized to minimize the position error of the machine. The dynamic performance of the kinematically redundant machine is simulated and compared with its two corresponding counterparts, one is redundantly actuated and the other is non-redundant. The proposed kinematically redundant machine possesses the highest position precision during the motion process and is applied to develop a precision planar mobile platform as an application example. The method is general and suitable for the dynamic modeling and redundant force optimization of other redundant parallel kinematic machines.     

Construction of a logical control by means of optimization of the Lypunov function when an object model is indeterminate

A method of constructing a logical control using if-then rules is proposed for situations when object mathematical models are indeterminate. The heart of the method is the idea of changing the sign of the relay control when a system moves away from its equilibrium position. The fact that a system moves away (or comes closer) to the position is indicated by the time derivative sign of the Lyapunov function defined as a positively definite quadratic form. The derivative is calculated in real time as the information about an object arrives.     

Wasp swarm optimization of the c‐means clustering model

This paper deals with clustering by optimizing the c‐means clustering model. For some data sets this clustering model possesses many local optima, so conventional alternating optimization (AO) will produce bad results. For obtaining good clustering results, the minimization procedure has to be kept from being trapped in these local optima, for example, by stochastic optimization approaches. Recently, we showed that ant colony optimization (ACO) can be effectively applied to the c‐means clustering model. In this paper, we introduce a wasp swarm optimization (WSO) algorithm to optimize the c‐means clustering model. In experiments with four benchmark data sets, the new WSO clustering algorithm is compared with AO and ACO. For data sets leading to c‐means models without local optima, both WSO and AO perform better and faster than ACO. For data sets leading to multiple local optima, WSO clearly outperforms both AO and ACO. © 2008 Wiley Periodicals, Inc.     

Process supervision by means of a hybrid model

The paper concerns process supervision tasks in which a continuous-variable system has to be moved into a globally defined final state. A hybrid model is proposed that describes the discrete-event behaviour as well as the quantitative behaviour of the continuous-variable system. The model consists of a Petri net and of differential equations whose validity depends on the marking of the net. The supervisory control task is solved by searching for a path within the Petri net from the current towards the final state and by using the relevant quantitative models to determine the speed of the state transitions. The results are illustrated by means of a laboratory tank system.     

Construction site layout planning and safety management using fuzzy-based bee colony optimization model

Neural Computing and Applications - The construction site layout planning is an activity that establishes the temporary facility location, thereby enhancing the efficiency of the construction....     

Integration of reduction and expansion processes in layout optimization

A tw0-stage layout optimization procedure, consisting of reduction and expansion processes, is presented. The object in developing this procedure is to use the advantages of both processes. In the reduction process, a reduced structure with a limited number of members and joints is established by solving large scale idealized problems. An expansion process is then employed, where members and joints are added to the initial reduced structure. At this stage, relatively small problems are solved, considering general variables, all relevant constraints and the real objective function.Humboldt Prize Awardee, Essen University. Paper presented at WCSMO1, held in Goslar, Germany, 1995     

Applications of linear programming in structural layout and optimization

Various computer methods have been developed for the optimal design of indeterminate structures, but it is not possible to guarantee that the result of any method will be a global optimum, rather than merely a local optimum. By temporarily neglecting the conditions of elastic compatibility and formulating a mathematical optimization problem based on the equilibrium conditions and the stress constraints, it is possible to obtain an approximate design which avoids merely local optima. In the cases examined, this design is close to the exact global optimum obtained by enforcing the compatibility conditions and is therefore a good starting point for an optimizing procedure. Examples include a graphical solution of a simple grillage known to have multiple local optima, and a sequence of planar trusses under alternate loading conditions. Linear programming is used to find the minimum weight truss designs satisfying equilibrium; this method eliminates extraneous members and leads to better indeterminate truss configurations than does a stress-ratio type algorithm.     

Many-objective control optimization of high-rise building structures using replicator dynamics and neural dynamics model

Recently the authors presented a single-agent Centralized Replicator Controller (CRC) and a decentralized Multi-Agent Replicator Controller (MARC) for vibration control of high-rise building structures. It was shown that the use of agents and a decentralized approach enhances the vibration control system. Two key parameters in the proposed control methodologies using replicator dynamics are the total population (total available resources or the sum of actuators forces) and the growth rate. In the previous research, a sensitivity analysis was performed to determine the appropriate values for the population size and growth rate. In this paper, the aforementioned control methodologies are integrated with a multi-objective optimization algorithm in order to find Pareto optimal values for growth rates with the goal of achieving maximum structural performance with minimum energy consumption. A modified neural dynamic model of Adeli and Park is used in this research to solve the many-objective optimization problem where the Normal Boundary Intersection method is employed to find Pareto optimality. Sample results are presented using a 20-story steel benchmark structure subjected to historical and artificial accelerograms.     

MOPSO算法及其在地下水监测网布局优化中的应用

在已有多目标粒子群优化算法（CMOPSO）研究和分析的基础上,为提高算法的聚合性和分布性,设计了一种新的精英档案维护及全局最优值选取策略,同时,使用动态全局最优值设置策略对原有算法的粒子速度更新公式进行扩展,以增强粒子的搜索能力,克服早熟现象。通过对疏勒河项目区地下水监测网空间布局多目标优化计算,表明该算法是求解大规模复杂多目标优化问题的一种有效手段。     

Analysis of steel bolted connections by means of a nonsmooth optimization procedure

A nonsmooth optimization procedure is herein proposed for the investigation of the bearing resistance of steel bolted connections. Taking into account the presence of nonlinear effects such as e.g. plasticity and interface interaction, and describing the resistance in bearing strength by means of a nonmonotone multi-valued reaction-displacement law obtained by experimental testing, the problem is formulated as a hemivariational inequality one. The latter is equivalent to a substationarity problem of the potential energy of the connection under investigation. This problem can be effectively treated numerically by applying an appropriately chosen nonconvex, nonsmooth optimization algorithm and in particular, the NSOLIB optimization algorithm based on the proximal bundle method has been applied. Two numerical examples whose results are compared to experimental testing results demonstrate the effectiveness of the proposed method.     

On controllability and trajectory tracking of a kinematic vehicle model

This paper presents some further results concerning the issues of controllability and trajectory tracking regarding a front-wheel drive vehicle kinematic model. A simple procedure for computing an open-loop control strategy that transfers the system between given initial and final states, is presented. In particular, the input function is computed by means of a set of linear algebraic equations. The resulting motion planning procedure allows us to present a control scheme for solving the trajectory (a time-parameterized reference signal) tracking problem. Various applications of the approach in forward and backward motions are considered, and simulation results are presented.     

基于新鲜度的冷链物流配送多目标优化模型*

针对传统选址模型忽视客户对物流服务水平满意程度这方面的不足,建立考虑客户满意度的基于新鲜度对损失成本影响的冷链配送中心选址模型。本文以客户满意度来表示物流的服务质量并结合易腐品的新鲜度对时间的敏感性特征,建立了最小化物流成本和最大化客户满意度的多目标优化模型,采用主要目标法将模型转化成单目标模型进行求解。求解算例所得的多组非劣解反映了物流成本与客户满意度之间的悖反关系,同时包含了以物流成本最小化为目标的传统选址模型的最优解,表明了多目标模型的优越性。对比结果说明新鲜度条件下建立的冷链物流配送网络模型比传统模型节省了更多的物流成本,进而验证了该模型的正确性。     

Solving the kinematics and dynamics of a modular spatial hyper-redundant manipulator by means of screw theory

In this contribution, a systematic methodology for solving the kinematic and dynamic analyses of a modular spatial hyper-redundant manipulator built with an optional number of serially connected three-legged in-parallel manipulators are presented. First, the kinematics and dynamics of the base module are carried out using the theory of screws and the principle of virtual work. Next, the expressions obtained for the base module are extended without significant effort to the spatial hyper-redundant manipulator under study. Finally, the proposed methodology of analysis is applied to a 18 degrees of freedom hyper-redundant manipulator.     

Performance optimization of integrated job-driven and resilience factors by means of a quantitative approach

Job-driven factors affect overall productivity and describe the characteristics influencing human performance. Resilience engineering (RE) is the capability of systems and groups to cope with disturbances and disruptions to enhance their performance. This study employs data envelopment analysis (DEA) approach to optimize the overall performance of a ceramic tile company by considering resilience and job-driven factors. The required data were collected via a standard questionnaire whose reliability was examined by statistical methods. In this regard, sensitivity analysis was performed to determine the most important factors. DEA results showed that job stress, job burnout, and management commitment play a central role in the investigated system. The overall results indicated that job-driven factors have a higher weight than resilience factors. This is one of the first studies that concurrently examine job-driven and resilience factors. Second, the present study uses DEA method in a ceramic tile manufacturer to achieve optimum performance. Third, the weights of all factors are computed for optimum redesign and re-engineering. Fourth, decision-makers may identify weak areas and strong points of their systems with respect to job-driven and resilience factors.     

The derivation of a kinematic model from the dynamic model of the motion of a riderless bicycle

This work deals with the modelling and control of a riderless bicycle (see Figure 1). It is assumed here that the bicycle is controlled by a pedalling torque, a directional torque, and by a rotor mounted on the crossbar that generates a tilting torque.In particular, a kinematic model of the bicycle's motion is derived by using its dynamic model. Then, using this kinematic model, a constraint point-to-point control problem is dealt with.     

微粒群算法在产品组件布局设计中的应用

提出了一种基于微粒群算法的自适应优化布局求解算法,该算法以组件特征模型为基础,在微粒群算法中引入人机交互技术,从整体上自动优化布局方案,以满足约束条件为目标。并以手机组件的布局求解为例,对该算法进行了验证。理论和实例分析表明,该算法能有效地生成多个手机组件布局方案。