Agent-based simulation of competitive and collaborative mechanisms for mobile service chains

A new paradigm for a mobile service chain’s competitive and collaborative mechanism is proposed in this study. The main idea of the proposed approach is based on a multi-agent system with optimal profit of the pull, push, and collaborative models among the portal access service provider (PASP), the product service provider (PSP), and the mobile service provider (MSP). To address the running mechanism for the multi-agent system, an integrated system framework is proposed based on the agent evolution algorithm (AEA), which could resolve all these modes. To examine the feasibility of the framework, a prototype system based on Java-Repast is implemented. The simulation experiments show that this system can help decision makers take the appropriate strategies with higher profits. By analyzing the expectations and variances (or risks) of each player’s profit, the interaction between and among entities in the chain is well understood. It is found that in the situation where a collaborative mechanism is applied, the performance of players is better as compared to the other two situations where a competitive mechanism is implemented. If some constraints are applied, the risk will be kept at a low level.     

Waiting time distribution in a class of discrete-time cyclic service multi-queue systems

A new approximate method is developed for finding the waiting and sojourn time distributions in a class of multi-queue systems served in cyclic order at discrete intervals. An immediate application for such a model is in communication networks where a number of different traffic sources compete to access a group of transmission channels operating under a time-slotted sharing policy. This system maps naturally onto a model in which the inter-visit time has a probability mass function of phase-type. We derive a set of matrix equations with easily tractable iterative procedures for their solution and controllable accuracy in their numerical evaluation. We then validate the analytical model against simulation and discuss the validity of the assumptions. This methodology can be extended to several other polling strategies.     

Digital systems and competitive responsiveness: The dynamics of IT business value

The mechanics of competition involve perception and reaction to competitor moves. Both incur delays that can be reduced by digital systems. Using system dynamics and the Red Queen paradigm, we modeled the impact of IT investments on response delays and business value, with the following results: (a) value has significant transient components; (b) value depends on investment level and the relative delays of competitors; and (c) relative delays affect the first-mover advantage. These results show that when assessing the value of IT investments, it is important to consider (a) the temporal pattern of benefits, not just their total magnitude, and (b) the impact of ongoing moves by competitors.     

On the impact of analyzing customer information and prioritizing in a service system

This paper examines prioritization in a service system and analyzes whether, in the presence of heterogeneous customers who have different needs and a costly sorting process, it pays to prioritize. In particular, in our model, sorting is costly because the task of gathering information to prioritize jobs consumes resources. We investigate a stylized model in which there are two classes of jobs — one whose waiting cost is high, called urgent, and the other whose waiting cost is low, called non-urgent. There are two types of employees, sorters, who collect information on a job and then decide whether it is urgent or non-urgent, and processors, who execute the job or provide the service. We begin by assuming that sorters categorize customers perfectly, and we relax this assumption later in the paper. We optimize two performance metrics, waiting costs (under a given budget) and total costs, and find the conditions under which prioritization is beneficial for these two metrics.     

Optimizing server placement in distributed systems in the presence of competition

Although the problem of data server placement in parallel and distributed systems has been studied extensively, most of the existing work assumes there is no competition between servers. Hence, their goal is to minimize read, update and storage cost. In this paper, we study the server placement problem in which a new server has to compete with existing servers for user requests. Therefore, in addition to minimizing cost, we also need to maximize the benefit of building a new server.Our major results include three parts. First, for tree-structured systems, we propose an O(|V|³k) time dynamic programming algorithm to find the optimal placement of k extra servers that maximizes the benefit in a tree with |V| nodes. We also propose an O(|V|³) time dynamic programming algorithm to find the optimal placement of extra servers that maximizes the benefit, without any constraint on the number of extra servers. Second, for general connected graphs, we prove that the server placement problems are NP-complete, and present three greedy heuristic algorithms, called Greedy Add, Greedy Remove and Greedy Add-Remove, to solve them. Third, we show that if the number of requests a server can handle (i.e., server capacity) is bounded, the server placement problem is NP-complete even for tree networks. We then derive a variation of the same set of greedy heuristic algorithms, with consideration of server capacity constraint, to solve the problem.Our experiment results demonstrate that the greedy algorithms achieve good results, when compared with the upper bounds found by a linear programming algorithm. Greedy Add performs best in the unconstrained model, yielding a benefit within 12% difference from the theoretical upper bound in average. For the constrained model, Greedy Remove performs best for smaller network sizes, while Greedy Add-Remove performs best for larger network sizes. On average, the heuristic algorithms yield a benefit within 13% difference from the theoretical upper bound in the constrained model.     

Determination of the locations and capacities of sugar cane loading stations in Thailand

In this paper, we address the problem of the location of sugar cane loading stations in Thailand. A loading station is a facility for collecting cane from small farmers; the cane is then transported to a sugar mill by a large truck. An improperly located loading station can result in high investment and transportation costs in the sugar industry. A mathematical model and a heuristic algorithm were developed to determine the suitable capacity of existing loading stations, the locations and capacities of new loading stations and the allocations of cane field harvests to each loading station. The model accounted for variations in the cane yield of each field during the harvesting periods and between crop years. The objective function was the minimization of the associated costs, including the investment costs, the transportation costs and the cost of the cane yield loss if the cane is not harvested at an optimal time. The performance of the developed heuristics was assessed under various scenarios. The results were shown to deviate slightly from the solution to the mathematical model. The sensitivities of the solutions under variations of the transportation cost, yield loss cost and investment costs were studied. The model was also applied to an industrial case study. A relevant and accurate solution was obtained.     

On the formulation of competitive negotiations in Web applications: The Latin-American market case

Work on electronic negotiation has motivated the development of systems with strategies specifically designed to establish protocols for buying and selling goods on the Web. On the one hand, there are systems where agents interact with users through dialogues and animations, helping them to find products while learning from their preferences to plan future transactions. On the other hand, there are systems that employ knowledge-bases to determine the context of the interactions and to define the boundaries inherently established by the e-Commerce. This paper introduces the idea of developing an agent with both capabilities: negotiation and interaction in an e-Commerce application via virtual reality (with a view to apply it in the Latin-American market, where both the technological gap and an inappropriate approach to motivate electronic transactions are important factors). We address these issues by presenting a negotiation strategy that allows the interaction between an intelligent agent and a human consumer with Latin-American idiosyncrasy and by including a graphical agent to assist the user on a virtual basis. We think this may reduce the impact of the gap created by this new technology.     

基于约束的旅游推荐系统的研究与设计

针对旅游领域的特点和传统推荐技术的应用局限性,提出一种基于约束的旅游推荐系统的设计方案,并对系统的推荐引擎进行了详细设计。系统通过可视化的知识获取工具高效地获取旅游领域知识、推荐规则、个性化规则等知识,使用交互＆个性化代理以会话式的交互方式逐步地启发用户的偏好和需要,利用多属性效用理论对推荐结果进行排序。相比传统的推荐方法,利用基于约束的推荐技术,能够为用户提供更加准确、个性化的旅游推荐服务。     

Function and service pattern analysis for facilitating the reconfiguration of collaboration systems

Recently, manufacturing companies have been attempting to increase competitiveness in their business collaboration with cooperative companies rather than within their own companies. In order to facilitate their collaboration, they are attempting to adopt or already using a collaboration system, which supports a number of functions and services. However, it is very difficult to apply existing systems into other organizations or industrial sections without customization or reconfiguration because functional or service requirements of users usually differ according to their domain knowledge. In order to re-apply and disseminate an existing system to other companies, therefore, the system must be reconfigured by modifying, upgrading, or newly developing some portions of the system. During the customization processes, functions or services of the system must be refined in order to satisfy user requirements. For facilitating the reconfiguration of collaboration systems, in this paper, we first define user patterns, and subsequently propose a method for investigating and analyzing patterns based on data mining approach. The proposed method validates normal versus abnormal patterns that show a drastic increase in the use of a specific function or service, and automatically makes the system recognize abnormal patterns as new normal patterns when abnormal patterns continue for a long time. We conduct experiments and comparison studies using an Apriori-like approach in order to establish the effectiveness of the proposed method. We also suggest a guideline for the reconfiguration of function modules or services with a specific collaboration system.     

On the undecidability of splicing systems

The notion of splicing system has been used to abstract the process of DNA digestion by restriction enzymes and subsequent religation. A splicing system language is the formal language of all DNA strings producible by such a process. The membership problem is to devise an algorithm (if possible) to answer the question of whether or not a given DNA string belongs to a splicing system language given by initial strings and enzymes.

In this paper the concept of a sequential splicing system is introduced. A sequential splicing system differs from a splicing system in that the latter allows arbitrarily many copies of any string in the initial set whereas the sequential splicing system may restrict the initial number of copies of some strings. The main result is that there exist sequential splicing systems with recursively unsolvable membership problem. The technique of the proof is to embed Turing machine computations in the languages.     

The impact of problem size on decision processes: an experimental investigation on very large choice problems with support of decision support systems

Abstract: Choice problems as a class of decision problems have attracted great attention for the last couple of decades. Among the frameworks and supporting theories used in their study, two have had the greatest impact: bounded rationality and cost–benefit. Both theories could find support from past empirical studies under different conditions or problem environments. In the past studies, problem size has been shown to play an important role in decision‐making. As problem size increases, a decision process may be detoured and the decision outcome may be different. In this paper we investigate the impact of problem size on three important aspects of the computer‐aided decision process – strategy selection, decision time/effort, and decision quality – through very large choice problems.     

Internal structure of coalitions in competitive and altruistic graphical coalitional games

This paper introduces a certain graphical coalitional game where the internal topology of the coalition depends on a prescribed communication graph structure among the agents. The game Value Function is required to satisfy four Axioms of Value. These axioms make it possible to provide a refined study of coalition structures on graphs by defining a formal graphical game and by assigning a Positional Advantage, based on the Shapley value, to each agent in a coalition based on its connectivity properties within the graph. Using the Axioms of Value the graphical coalitional game can be shown to satisfy properties such as convexity, fairness, cohesiveness, and full cooperativeness. Three measures of the contributions of agents to a coalition are introduced: marginal contribution, competitive contribution, and altruistic contribution. The mathematical framework given here is used to establish results regarding the dependence of these three types of contributions on the graph topology, and changes in these contributions due to changes in graph topology. Based on these different contributions, three online sequential decision games are defined on top of the graphical coalitional game, and the stable graphs under each of these sequential decision games are studied. It is shown that the stable graphs under the objective of maximizing the marginal contribution are any connected graph. The stable graphs under the objective of maximizing the competitive contribution are the complete graph. The stable graphs under the objective of maximizing the altruistic contribution are any tree.     

On the theory of realization of quasilinear systems described by differential equations in a Hilbert space

We consider a system-theoretic methodology of mathematical modeling involved in the structural identification of continuous nonlinear dynamic systems with programmable position control. We present various functional-analytical modifications of a characteristic criterion for exogenous (“input-output”) behavior of these systems that permit, by virtue of this criterion, model realizations in the class of quasilinear nonstationary ordinary differential equations describing states in a separable Hilbert space. The study was sponsored by the Russian Foundation for Basic Research (Grant No. 05-01-00623), Basic Research Program No. 22 of the Presidium of the Russian Academy of Sciences, Grant of the President of the Russian Federation for the Governmental Support of Scientific Schools of the Russian Federation (No. NSh-1676.2008). __________ Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 82–95, September–October 2008.     

The rise and fall of the competitive local exchange carriers in the U.S.: An institutional perspective

The debacle of the telecommunications industry at the turn of the millennium resulted in significant consequences for investors, workers, financial institutions, telecom companies, and the economy in general worldwide. In the midst of the telecom bubble, the CLECs (competitive local exchange carriers) adopted similar or identical business plans and saturated the market, which resulted in destructive competition. In this study, we investigate the isomorphic business models of the CLECs from the perspectives of the new institutional theory. We argue that the combined coercive, mimetic, and normative institutional forces exerted on the companies by the actors who controlled the funding, managed the business, and provided the information fashioned the isomorphic CLEC business models, which in turn contributed to the demise of these companies and thus the burst of the telecom bubble. Evidence of the institutional influences on CLECs and the actors exerted the influences are presented and their consequences are discussed. Qing Hu is Professor of Information Systems in the Department of Information Technology & Operations Management at Florida Atlantic University. He earned his Ph.D. in Computer Information Systems from the University of Miami. His research interests include economics of information technology (IT), IT strategy and management, and information security. His work has been published in leading academic journals including Information Systems Research, Journal of Management Information Systems, Communications of the ACM, Communications of the AIS, California Management Review, and IEEE Transactions on Software Engineering. He also serves as associate and guest-editors for a number of IS journals and major conferences. C. Derrick Huang is Assistant Professor in the Department of Information Technology & Operations Management in the College of Business at Florida Atlantic University. Previously, as a practitioner, he held executive-level positions in the area of marketing and strategic planning in a number of high-tech companies. Dr. Huang’s research interest lies in the business value and strategic impact of information technology in organizations, and his current focus is on the economics and management of information security investments. He holds Ph.D. from Harvard University.     

分布式问题求解中的妥协策略

基于多agent系统的分布式约束满足(CSP)问题的求解进程依赖于agent间的有效交互。该文针对着色问题(GCP)的分布式求解,提出了agent妥协的概念。通过妥协,两个相邻agent改变了各自原有的局部目标,实现了相邻约束的满足。模拟实验表明,妥协策略有助于提高分布式GCP问题的求解性能。该文还讨论了不同的妥协实现方式对性能的影响。     

Predicting the optimum number, location, and signal sound level of auditory warning devices for manufacturing facilities

An analytical method for predicting the optimum number, location, and signal sound level of auditory warning devices is proposed. Factors which influence the perception of alarm signals, namely, ambient sound level, machining workstations (locations and their generated sound levels), workers' locations, and recommended signal sound level reaching workers are considered in the development of the objective function and constraints. Solving the multiple alarm location problem with a nonlinear programming technique yields the minimum number of auditory warning devices, their locations, and the minimum required sound level of warning signals. Two examples are given to demonstrate the applications of the predictive model.

Relevance to industry

The method presented in this paper enables engineers to determine the optimum number and location of auditory warning devices for manufacturing facilities to ensure adequate perception of warning signals. Since the proposed method is analytical in nature, it helps reduce trial-and-error effort normally spent in locating the alarm devices, thus saving both time and money.     

Design of multivariable feedback systems with infinite gain margin and decoupling

This letter discusses the problem of designing a feedback compensator that attains the infinite gain margin under the uncertainties of feedback gains. A sufficient condition is given for the existence of compensators and then it is shown that the condition becomes necessary subject to the requirement that the feedback system is decoupled. The nonlinear case is also discussed.     

多追捕者-单-逃跑者追逃问题实现成功捕获的约束条件

针对包含有n个追捕者及1个逃跑者的2维平面多机器人追逃问题,对实现成功捕获的约束条件进行了研究.经过理论分析得出:在机器人拥有全局视野的情况下,即使单一逃跑者性能优于每个追捕者,只要满足追捕者与逃跑者的速率比大于sin(π/n),逃跑机器人落在追捕机器人所构成的凸多边形内部且逃跑者和追捕者构成的相邻追-逃阿波罗尼奥斯圆满足两两相交(相切)这2个约束条件,则追捕者通过选择合适的追捕策略就一定可以实现成功抓捕.此外,还给出了在此约束条件下的追捕者和逃跑者的追逃策略.多组仿真实验同样证明了本文提出的约束条件是正确的.     

A hybrid parallel solver for systems of multivariate polynomials using CPUs and GPUs

This paper deals with a problem of finding valid solutions to systems of polynomial constraints. Although there have been several quite successful algorithms based on domain subdivision to resolve this problem, some major issues are still demanding further research. Prime obstacles in developing an efficient subdivision-based polynomial constraint solver are the exhaustive, although hierarchical, search of the zero-set in the parameter domain, which is computationally demanding, and their scalability in terms of the number of variables. In this paper, we present a hybrid parallel algorithm for solving systems of multivariate constraints by exploiting both the CPU and the GPU multicore architectures. We dedicate the CPU for the traversal of the subdivision tree and the GPU for the multivariate polynomial subdivision. By decomposing the constraint solving technique into two different components, hierarchy traversal and polynomial subdivision, each of which is more suitable to CPUs and GPUs, respectively, our solver can fully exploit the availability of hybrid, multicore architectures of CPUs and GPUs. Furthermore, our GPU-based subdivision method takes advantage of the inherent parallelism in the multivariate polynomial subdivision. We demonstrate the efficacy and scalability of the proposed parallel solver through several examples in geometric applications, including Hausdorff distance queries, contact point computations, surface–surface intersections, ray trap constructions, and bisector surface computations. In our experiments, the proposed parallel method achieves up to two orders of magnitude improvement in performance compared to the state-of-the-art subdivision-based CPU solver.     

State-of-the-art of design,evaluation, and operation methodologies in product service systems

Product service systems (PSS) – integration of products and services – with aims to achieve economic profit and reduce environmental impacts, is a hot issue in academia. The purpose of this study is to comprehend the state-of-the-art in the field of PSS design, evaluation, and operation methodologies (PSS-DEOM) by conducting a systematic literature review. Up to 258 publications related to PSS-DEOM were reviewed and divided into three categories: PSS design methodologies (PSS-DM), PSS evaluation methodologies (PSS-EM), and PSS operation methodologies (PSS-OM). Based on the findings, future research trends were proposed and discussed.