A novel approach to coordination of multiple robots with communication failures via proximity graph

In this paper, we investigate the coordination problem of multiple robots with limited communication ranges and communication failures. A novel rendezvous algorithm via proximity graph is developed so that the robot group can achieve rendezvous when the communication links satisfy an ergodic assumption. The convergence proof of the algorithm is established based on the tools from rooted graph theory. The effectiveness of the algorithm is illustrated by numerical examples in a 3D space.     

Uniform metrical task systems with a limited number of states

We give a randomized algorithm (the “Wedge Algorithm”) of competitiveness for any metrical task system on a uniform space of k points, for any k?2, where , the kth harmonic number. This algorithm has better competitiveness than the Irani-Seiden algorithm if k is smaller than 10⁸. The algorithm is better by a factor of 2 if k<47.     

PLC的选型与系统配置

随着PLC的推广普及,种类繁多的PLC的功能、价格及适用场合也各不相同。对于从事PLC设计或应用的技术人员,要设计出性能价格比最优的控制系统,应掌握PLC的选型与系统配置的一般方法和原则,包括机型的选择、硬软件的选择、支撑条件的选择和环境适应性的选择。     

以太网交换机的选择

本文对以太网交换机的分类和性能参数进行了讨论，在此基础上给出了选择交换机的基本原则和主要依据。     

Bidirectional heuristic search with limited resources

Heuristic search strategies have useful applicable problem solving in AI. It has been observed that bidirectional heuristic search algorithms can be potentially than their unidirectional counterparts. However, the problem with bidirectional search in practice is to make the two search fronts (forward and backward) meet in the middle. De Champeaux suggested a front-to-front algorithm [3] that overcomes this problem. But the disadvantage of that algorithm is that it is computationally very expensive. In this paper, we suggest a new front-to-front algorithm that is computationally much less expensive. Our algorithm does not guarantee optimality always, but its solution quality and execution time can be controlled by some external parameters. Finally, we present some experimental results on a generic state space problem, viz. 15-puzzle, showing the effectiveness of our algorithm.     

基于Flash软件多选题的设计

本文以多选题的设计为例,介绍了Flash的制作方法,为大家提供一定的参考。     

Probabilistic robust design with linear quadratic regulators

In this paper, we study robust design of uncertain systems in a probabilistic setting by means of linear quadratic regulators (LQR). We consider systems affected by random bounded nonlinear uncertainty so that classical optimization methods based on linear matrix inequalities cannot be used without conservatism. The approach followed here is a blend of randomization techniques for the uncertainty together with convex optimization for the controller parameters. In particular, we propose an iterative algorithm for designing a controller which is based upon subgradient iterations. At each step of the sequence, we first generate a random sample and then we perform a subgradient step for a convex constraint defined by the LQR problem. The main result of the paper is to prove that this iterative algorithm provides a controller which quadratically stabilizes the uncertain system with probability one in a finite number of steps. In addition, at a fixed step, we compute a lower bound of the probability that a quadratically stabilizing controller is found.     

Scheduling projects with limited number of preemptions

A recent paper (Ballestín F, Valls V, Quintanilla S. Preemption in resource-constrained project scheduling. European Journal of Operational Research 2008;189:1136–152) revealed the potential benefits of allowing one interruption when scheduling activities in a resource-constrained project. This paper further investigates the effect of interruption on project length in more general cases. To achieve this, a new model that covers most practical applications of discrete activity preemption is proposed and a metaheuristic algorithm for the problem is developed. Computational experiments on the standard j120 and j30 sets generated using ProGen study the difference in makespan between allowing m$m$ interruptions per activity, m=0,1,2,…$m=0,1,2,\dots$ . In the second part of the paper the usefulness of preemption in the presence of due dates is analysed.     

嵌入式Linux系统的选择

随着嵌入式Linux系统的迅速发展,目前市场上已经出现许多各具特色的成型产品,如何在这众多的产品中选择一个适合开发项目的系统显得尤为重硬。文章从实时性、开发工具、应用程序开发移植等几方面对几种有代表性的嵌入式Linux系统做出分析比较,同时结合项目的情况,给出了符合实际需要的选择方案。     

Supporting mass customization with agent-based coordination

Mass customization (MC) often implies a value chain with several spatially distributed actors that require extensive coordination. Agent technology is beginning to be utilized in supply chain management because of its ability to facilitate collaboration and coordination. Thus, agents are suitable for constructing MC environments and interfacing the various participants working together to archive the common goal of producing customized goods. This paper presents a multi-agent system architecture for MC, which takes into account the coordination problems that exist in MC. Because of asymmetric and incomplete knowledge bases, agents may be limited in global planning and scheduling. Therefore, we suggest a three-tier model of coordination and utilize partial global plans for addressing the coordination problem. Finally, we provide an example application and a prototype implementation for the MC coordination. An earlier version of this paper was presented at the WeB03 workshop.     

Exogenous coordination of concurrent software components with JavaBIP

A strong separation of concerns is necessary in order to make the design of domain‐specific functional components independent from cross‐cutting concerns, such as concurrent access to the shared resources of the execution platform. Native coordination mechanisms, such as locks and monitors, allow developers to address these issues. However, such solutions are not modular; they are complex to design, debug, and maintain. We present the JavaBIP framework that allows developers to think on a higher level of abstraction and clearly separate the functional and coordination aspects of the system behavior. It implements the principles of the Behavior, Interaction, and Priority (BIP) component framework rooted in rigorous operational semantics. It allows the coordination of existing concurrent software components in an exogenous manner, relying exclusively on annotations, component APIs, and external specification files. We introduce the annotation and specification syntax of JavaBIP and illustrate its use on realistic examples, present the architecture of our implementation, which is modular and easily extensible, and provide and discuss performance evaluation results. Copyright © 2017 John Wiley & Sons, Ltd.     

Peer-to-peer semantic coordination

Semantic coordination, namely the problem of finding an agreement on the meaning of heterogeneous schemas, is one of the key issues in the development of the Semantic Web. In this paper, we propose a method for discovering semantic mappings across hierarchical classifications (HCs) based on a new approach, which shifts the problem of semantic coordination from the problem of computing linguistic or structural similarities (what most other proposed approaches do) to the problem of deducing relations between sets of logical formulae that represent the meaning of concepts belonging to different schema. We show how to apply the approach and the algorithm to an interesting family of schemas, namely hierarchical classifications, and present the results of preliminary tests on two types of hierarchical classifications, web directories and catalogs. Finally, we argue why this is a significant improvement on previous approaches.     

Multi-leader coordination algorithm for networks with switching topology and quantized information

This paper analyzes the stability and convergence properties of a proportional–integral protocol for coordination of a network of agents with dynamic information flow and quantized information exchange. In the setup adopted, each agent is only required to exchange its coordination state with its neighboring agents, and the desired reference rate is only available to a group of leaders. We show that the integral term of the protocol allows the agents to learn the reference rate, rather than have it available a priori, and also provides disturbance rejection capabilities. The paper addresses the case where the graph that captures the underlying network topology is not connected during some interval of time or even fails to be connected at all times.     

Communication complexity in a 3-computer model

It is proved that the probabilistic communication complexity of the identity function in a 3-computer model isO(n).This research was supported by Latvian Science Council Grant No. 93.599.     

Motion coordination for industrial robotic systems with redundant degrees of freedom

This work investigates how to distribute in an optimum fashion the desired movement of the end-effector of an industrial robot with respect to the workpiece, when there are redundant degrees of freedom, such as a positioning table. The desired motion is given as a series of acceleration functions in respective time intervals. The constraints of the optimisation are the available acceleration limit of axes, such as the table axes, the upper bounds to velocity and displacement of each axis and the avoidance of singular point areas of the robot, as defined by its manufacturer. The optimisation criterion is minimum total work for the motion. A genetic algorithm was used to solve the problem. The fitness function of the genetic algorithm calls a kinematics and dynamics simulation model of the robotic installation constructed in Matlab™, in order to compute the work consumed and to check possible violation of constraints. Examples of straight line and circular movement are given to prove the concept. Results are encouraging, yet demand on computing power is high.     

Unbounded parallel-batch scheduling with family jobs and delivery coordination

We study a scheduling problem that integrates parallel-batch production with family jobs and job delivery at the same time. The jobs are first processed on an unbounded parallel-batch machine and then delivered in batches to their specified customers by a transportation vehicle. We assume that jobs from different families (customers) cannot be processed together by the batch machine and also transported together by the vehicle. The objective is to minimize the time when the vehicle finishes delivering the last delivery batch to its customer and returns to the machine. We first show that the problem is NP-hard, and then propose for it a heuristic algorithm with a worst-case performance ratio of 3/2.     

Disturbed Exploitation compact Differential Evolution for limited memory optimization problems

This paper proposes a novel and unconventional Memetic Computing approach for solving continuous optimization problems characterized by memory limitations. The proposed algorithm, unlike employing an explorative evolutionary framework and a set of local search algorithms, employs multiple exploitative search within the main framework and performs a multiple step global search by means of a randomized perturbation of the virtual population corresponding to a periodical randomization of the search for the exploitative operators. The proposed Memetic Computing approach is based on a populationless (compact) evolutionary framework which, instead of processing a population of solutions, handles its statistical model. This evolutionary framework is based on a Differential Evolution which cooperatively employs two exploitative search operators: the first is based on a standard Differential Evolution mutation and exponential crossover, and the second is the trigonometric mutation. These two search operators have an exploitative action on the algorithmic framework and thus contribute to the rapid convergence of the virtual population towards promising candidate solutions. The action of these search operators is counterbalanced by a periodical stochastic perturbation of the virtual population, which has the role of “disturbing” the excessively exploitative action of the framework and thus inhibits its premature convergence. The proposed algorithm, namely Disturbed Exploitation compact Differential Evolution, is a simple and memory-wise cheap structure that makes use of the Memetic Computing paradigm in order to solve complex optimization problems. The proposed approach has been tested on a set of various test problems and compared with state-of-the-art compact algorithms and with some modern population based meta-heuristics. Numerical results show that Disturbed Exploitation compact Differential Evolution significantly outperforms all the other compact algorithms present in literature and reaches a competitive performance with respect to modern population algorithms, including some memetic approaches and complex modern Differential Evolution based algorithms. In order to show the potential of the proposed approach in real-world applications, Disturbed Exploitation compact Differential Evolution has been implemented for performing the control of a space robot by simulating the implementation within the robot micro-controller. Numerical results show the superiority of the proposed algorithm with respect to other modern compact algorithms present in literature.     

An incentive model of duopoly with government coordination

A static market model of duopoly, with the government influencing the market, is formulated as a Stackelberg game with one leader and two Nash followers. By using a strategy which is a function of the decisions of the Nash duopolists, the government may induce them to virtually cooperate. Marginal cost, price, elasticity of demand, total profits and consumers' welfare, when this incentive mechanism is used, are compared to the corresponding quantities under voluntary cooperation.