Integrated use of fuzzy c-means and convex programming for capacitated multi-facility location problem

In this study a fuzzy c-means clustering algorithm based method is proposed for solving a capacitated multi-facility location problem of known demand points which are served from capacitated supply centres. It involves the integrated use of fuzzy c-means and convex programming. In fuzzy c-means, data points are allowed to belong to several clusters with different degrees of membership. This feature is used here to split demands between supply centers. The cluster number is determined by an incremental method that starts with two and designated when capacity of each cluster is sufficient for its demand. Finally, each group of cluster and each model are solved as a single facility location problem. Then each single facility location problem given by fuzzy c-means is solved by convex programming which optimizes transportation cost is used to fine-tune the facility location. Proposed method is applied to several facility location problems from OR library (Osman & Christofides, 1994) and compared with centre of gravity and particle swarm optimization based algorithms. Numerical results of an asphalt producer’s real-world data in Turkey are reported. Numerical results show that the proposed approach performs better than using original fuzzy c-means, integrated use of fuzzy c-means and center of gravity methods in terms of transportation costs.     

Natural Hairstyle Modeling and Animation

In this paper, we develop a hairstyle modeling and animation technique specifically designed for human hairs, and we report several experimental results. Using simplified cantilever beam model and one-dimensional projective differential equations of angular momenta, we give a practical solution to the problem of enormous complexity. Even though our hair animation algorithm is an approximate solution, it includes all the relevant dynamic elements such as gravity, wind, inertia, air-resistance, hair-to-head, and hair-to-hair friction forces. Collision is an important element that makes a collection of hair strands look like hair. We develop an accurate but efficient hair-to-head and hair-to-hair collision detection and treatment algorithm. The algorithm produces quite realistic results; still it runs at an interactive speed. An interesting contribution of our algorithm is that it unifies hairstyle modeling and animation into a single equation, so that (1) hairstyling can be done under the effects of gravity and other internal or external forces, and (2) original hairstyle is more or less restored even after the initial hair is tangled by the application of external forces or head movements.     

Trapping—A control phenomenon of spinning drag-free satellites

A drag-free satellite contains a proof mass in an internal cavity and is controlled in translation so that it never touches the proof mass. The satellite shields the proof mass from external forces, thus allowing the proof mass to follow a drag-free orbit. Spinning the satellite is desirable because it attenuates the effect of proof mass disturbing forces and simplifiies the attitude control. The design of a translation controller for a spinning drag-free satellite typically includes a deadspace to eliminate chatter. This design feature and the inability to locate precisely the mass center give rise to a phenomenon called trapping that potentially could waste significant amounts of propellant. A theory is developed and experimentally verified that explains the role of these factors and provides insight into the effect of other control parameters. An analog application of estimation theory to observe the center-of-mass location was evaluated and found to be a practical method to eliminate mass center uncertainties as a cause of trapping and its associated propellant wastage. It is further concluded that, by proper selection of control parameters and deadspace shape, translation control of a spinning satellite is quite feasible.     

基于空间最大类间距的像素群分割优化

目标分割是利用图像的时空先验知识对像素点进行逐点分类的一个过程,目标的固有属性体现在密度及其形状即二维平面的空间分布上。既往的阈值分割大多仅利用了目标的密度信息,而忽略了其空间分布信息。鉴于形状先验知识难以获得,提出利用双阈值分割得到临界区域和目标重心,其后以临界区域像素群距目标重心的距离作为形状的空间分布信息,并由最大类间距算法对该距离进行分割从而实现优化。实验结果显示算法在降低噪声和削弱阴影的同时,有效地改善了目标提取的完整性。     

Control and simulation of a constrained dynamic two-link system

In this paper a solution to the attitude control problem of a two-link planar system, whose angular momentum about the centre of gravity is constant, is presented. Reference trajectories for simulating the motion of the constrained dynamic system are found by specifying the internal variables of the system and solving for the corresponding external variables. It is shown that the angular momentum constraint has quasi-holonomic character because it can be employed to reduce the dimensionality of the system by eliminating half a degree of freedom. A controller is designed for the reduced dynamic system and tested by digital computer simulation. It is shown that the same controller can be used for the unreduced system if the angular momentum constraint is a linear function of the states of the system. Such an approach, however, cannot be employed if the constraint is a non-linear function of the system state. In this case a controller must be designed which stabilizes both the system and the constraint equation. Computer simulations of the diving motion of a human are presented to illustrate the control approach.     

Kinematic analysis of footstep strategies in asymmetrical lifting and lowering tasks

Two footstep strategies associated with expert workers and two associated with novice workers were studied for lifting and lowering a 12 kg box. Kinematic variables, L5/S1 resultant moments and body postures of eight healthy male subjects were used to analyse the effects of the footstep strategies. A tridimensional dynamic rigid body model was used to estimate L5/S1 resultant moment, using inertial forces to estimate external forces; these procedures were validated with force platforms. Results showed that expert strategies either reduced the path of the subject's centre of gravity or reduced the asymmetry of posture at deposit. The footstep strategies showed no consistent effect on L5/S1 resultant moment. The use of different footstep strategies might be aimed at different goals, which may depend on the context. On the one hand, the reduction in the path of the subject's centre of gravity might represent a mean to reduce the effort required and avoid fatigue, which might be appropriate in some circumstances; on the other hand, the reduction of asymmetry of posture at deposit might be more appropriate in other circumstances. Footstep strategies will deserve further attention since this study showed that they can play an important role in reducing the risks of injury.

Relevance to industry

Manual materials handling is a major known source of industrial injury. Biomechanical studies of handling strategies really used by workers should help understand the loadings encountered in real handling tasks, which may lead to the identification of safer handling strategies.     

弯曲树枝和分形树根的三维模拟

枝条的逼真度在很大程度上影响着整棵树的形态效果,为了模拟出更符合自然规律的三维树,结合了分形算法和材料力学原理,提出了基于重力场的三维弯曲枝条和分形树根的模拟方法。枝条的弯曲程度体现了它的受力情况,同时也可以用杨氏弹性模量来控制其弯曲度;另一方面,采用X3D及Java,运用分形算法结合X3D的Extrusion节点模拟了分形弯曲树根的向地性。用户只需要输入相关参数就可以得到形态较为逼真的三维树。同时将树的地下部分与地上部分有机地结合在一起,模拟了基于重力场的三维树形态。实验结果表明,该方法可以比较方便地生成形态逼真的三维分形树。     

高效率医疗植入式刺激装置无线充电系统

基于对医疗植入式刺激装置外部供电或充电的核心——松耦合变压器的研究,利用有限元软件进行仿真和实际分析,提出针对植入式应用的磁路结构,得出优化后的松耦合变压器结构,并制作实际电路,对其传输效率进行对比分析。该设计可以满足高效率医疗植入式刺激装置的供电需求,同时还可用于某些密闭化学、生物装置的内部供电及特殊场合内部监控装置的供电。     

Ergonomic assessment of handle design by means of electromyography and subjective rating

Stress and strain during manual tool handling not only depend on factors such as weight to be handled, but are also determined by the design of the man-machine interface. In this study, three different handles of electric hedge-clippers were analysed; the results of a comparative investigation into the physiological cost demanded by the use of the different handles are discussed. Muscular strain was measured via surface electromyography in laboratory experiments with nine male subjects. The results showed significant differences in physiological cost depending on both work height and the handles' shape. Systematic differences in muscular strain between the utilized tools were found, despite the fact that all clippers were compensated with respect to weight and location of the centre of gravity. One of the handle designs enabled working under varying conditions (work height and direction) at a reduced level of muscular strain of the right arm. Results from the physiological evaluation were partly supported by the working persons' own subjective experience. The results of this investigation show that further ergonomic tool and handle design is necessary.     

Developing alternative design concepts in VR environments using volumetric self-organizing feature maps

The conceptual design process has not benefited from conventional computer-aided design (CAD) technology to the same degree as embodiment design because the creative activities associated with developing and communicating alternative solutions, with minimal detail, is far less formulaic in its implementation. Any CAD system that seeks to support and enhance conceptual design must, therefore, enable natural and haptic modes of human–computer interaction. A computational framework for economically representing deformable solid objects for conceptual design is described in this paper. The physics-based deformation model consists of a set of point masses, connected by a series of springs and dampers, which undergo movement through the influence of external and internal forces. The location of each mass point corresponds to a node on a 3D mesh defined by a volumetric self-organizing feature map (VSOFM). A reference mesh is first created by fitting the exterior nodes of the VSOFM to sampled data from the surface of a primitive shape, such as a cube, and then redistributing the interior nodes to reflect evenly spaced hexahedral elements. Material properties are introduced to the mesh by assigning a mass value to individual nodes and spring coefficients to the nodal connections. Several illustrations involving the redesign of an ergonomic writing pen is used to demonstrate how the proposed virtual reality-based modeling system will permit the industrial designer to interactively change the shape and function of a design concept.     

基于BIRCH聚类的物流配送设施选址算法

物流配送设施的选址对于物流成本、在途时间影响巨大.其特点包括：配送设施选址和配送路线交互影响、多层级选址、配送设施存件数量均衡性等.本文通过分析物流配送设施选址的特点设计了一个基于BIRCH聚类的物流配送设施选址算法,融合了BIRCH聚类算法和基于Dijkstra距离的重心法,为物流配送设施选址提供了更好的方案,大幅节约长期运营成本.     

Control of flexible joint robots via external linearization approach

Based on the feedback linearization structure algorithm of differential geometric nonlinear control theory, an external linearization approach to the control of multilink flexible joint robots is considered in this article. The resulting externally linearized and input-output decoupled closed-loop system contains a linear subsystem and a nonlinear subsystem. The linear part describing the rigid motor motions is suitable for the design of nominal trajectory following control. However, the nonlinear joint deformation subsystem will cause perturbations in the nominal trajectory. To actively damp out the elastic vibrations and to render the complete closed-loop system robust to uncertainty in system parameters, a combined LQR stabilizer and servocompensator is used as the internal stabilization and error correcting control. The tracking errors of the end effector caused by the quasi-static joint deflections due to gravity can be compensated for by taking into account the nominal deflections in the trajectory planning and LQ regulation. A three-link PUMA type arm is tested via simulation.     

Multi-channel satellite cloud image fusion in the tetrolet transform domain

A novel multi-channel satellite cloud image fusion algorithm constructed in the tetrolet transform domain is proposed. Tetrolet is successfully applied in image denoising, image sparse representation, and image restoration. In this paper, tetrolet transform was introduced into the field of satellite cloud image fusion since its sparse degree is high. Tetrolet can describe the geometric structure feature of the satellite cloud image very well. First, tetrolet transform must be implemented into the multi-channel satellite cloud images to obtain low- and high-frequency coefficients and corresponding covering distribution values. Then, a Laplacian pyramid algorithm must be used to decompose the low-frequency portion in the tetrolet domain by averaging the values of its top layer and taking the maximum absolute values of the other layers. While reconstruction is implemented in this stage, the algorithm takes the maximum standard deviation of the high-frequency parts for each block in the tetrolet domain. Last, an inverse tetrolet transform must be used to obtain the final fused image. This paper compares the proposed image fusion algorithm to three similar image fusion algorithms: the curvelet image fusion algorithm, the non-subsampled contourlet transform (NSCT) image fusion algorithm, and the tetrolet image fusion algorithm. Mutual information, joint entropy, mean structural similarity (MSSIM), standard deviation, and average relative deviation are used as objective criteria to evaluate the quality of the fused images. In order to verify the efficiency of the proposed algorithm, the fusion cloud image is used to determine the centre location of eye and non-eye typhoons. Experimental results show that the proposed algorithm performs well when fusing the information in multi-channel satellite cloud images and improves the precision of locating the typhoon’s centre. The proposed algorithm’s comprehensive performance is superior to similar image fusion algorithms.     

Fuzzy adaptive anisotropic filter for medical images

Abstract: An adaptive anisotropic diffusion filter for images is proposed in this paper. First, the gradient of an image was calculated by a novel fuzzy‐rule‐based gradient operator. Accordingly, the centre of gravity of a histogram of the gradient image was estimated and it was assigned as an edge threshold. In conventional anisotropic filters, the conduction coefficients have to be selected by an operator. However, in this study, the centre of gravity of the histogram was assigned as the conduction coefficient of the anisotropic filter. Consequently, an adaptive anisotropic image filter which automatically sets its conduction coefficient without user intervention was developed. The image filter achieved was tested with various medical images.     

基于改进的K-means聚类的多区域物流中心选址算法

针对当前多区域物流中心选址需建立配送中心个数不定、位置、覆盖范围不明的问题,本文提出了一种改进的k-means聚类算法,以城市经济引力模型为基础,将城市运输距离与居民消费能力的指标相结合,重新定义对象之间相似性度量的距离因子.并将密度思想引入k-means算法,提出类内差分均值的概念确定最优聚类数.实现分区后,分别在这些区域中利用重心法对配送中心进行最终的确定.最后实例分析了在西部地区37个城市创建物流配送中心的选址过程,并通过和传统的k-means聚类的选址结果对比,说明改进后的算法不仅可以节省配送时间,而且大大降低了运输成本,有很好的经济利用价值.     

A new front updating solution applied to some engineering problems

Summary An automatic mesh generation dealing with domains of an arbitrary shape could be realized by an advancing front method. The mesh generator based on this method creates triangle elements inside a domain starting with the polygonal (polyhedral in 3D) discretisation of its border. In this paper an original algorithm for the front updating procedures as a part of the mesh generator is presented. The proposed algorithm provides an efficient mesh generation procedure. It has been verified on the various domains with complex geometry and with nonuniform distribution of edge nodes such as the discretisation of the switched reluctance motor and power cable configuration, respectively. The related finite element calculations are carried out.     

Bayesian shape model for facial feature extraction and recognition

A facial feature extraction algorithm using the Bayesian shape model (BSM) is proposed in this paper. A full-face model consisting of the contour points and the control points is designed to describe the face patch, using which the warping/normalization of the extracted face patch can be performed efficiently. First, the BSM is utilized to match and extract the contour points of a face. In BSM, the prototype of the face contour can be adjusted adaptively according to its prior distribution. Moreover, an affine invariant internal energy term is introduced to describe the local shape deformations between the prototype contour in the shape domain and the deformable contour in the image domain. Thus, both global and local shape deformations can be tolerated. Then, the control points are estimated from the matching result of the contour points based on the statistics of the full-face model. Finally, the face patch is extracted and normalized using the piece-wise affine triangle warping algorithm. Experimental results based on real facial feature extraction demonstrate that the proposed BSM facial feature extraction algorithm is more accurate and effective as compared to that of the active shape model (ASM).     

基于遗传算法优化植物仿真的应用研究

L-System不仅可以模拟单株植物,而且可以模拟一片森林。由于森林中的树木形状不仅受内部信息的影响,还受外界多种因素影响。所以森林仿真是一个多参数的问题,遗传算法是解决多参数的问题有力工具。文章中使用遗传算法优化森林中树木的仿真。     

A Model for Locating Park-and-Ride Facilities on Urban Networks Based on Maximizing Flow Capture: A Case Study of Isfahan, Iran

Traffic congestion is one of the main problems in large cities for which several approaches have been proposed. Park-and-ride is one of the best approaches that can remove traffic from the traffic network. Park-and-ride facilities are an important part of urban mass transit systems, effectively extending the service area and attracting commuters and other people who may not otherwise have used mass transit. However, its efficiency depends on its location in the urban network. In this research, we focus on travel time of shortest paths instead of the distance criterion for computing network traffic and develop a model for finding the best location(s) for siting park-and-ride systems so as to minimize the network traffic. The model is formulated based on population points, potential sites for park-and-ride establishment, and several Central Business District (CBDs). Then we present a Genetic algorithm that has been proved to be efficient in solving large size problems. Finally, the proposed model is used to locate park-and-ride facilities in the city of Isfahan, Iran.     

可探测社区稳定结构的局部社区发现算法

社交网络的动态变化使社区发现的精确度面临更高挑战。目前提出的大部分算法都是以寻求模块度最优解来发现社区,但往往会忽略所发现的社区结构是否稳定。根据力学平衡原理即当一个物体所受内部力和外部力平衡的条件下可达稳定状态,因此基于点的稳定性机制,判断节点来自社区内部连边数量与来自外部社区连边数量的最大值是否保持平衡,提出一种可探测稳定结构的局部社区发现算法。网络的稳定性大小与社区的结构有很大的关系,因此将网络的稳定性作为一种新的评价社区结构优良的标准。通过在真实网络和人工集成网络上进行实验对比发现提出的算法的社区结构稳定度比其他算法高,同时能发现精确度高的社区。