Search

Rescheduling disrupted railway traffic is computationally hard even for small problem instances. Disruptions may not be known beforehand and can manifest themselves even when trains are en-route, and they are usually resolved by human experts. Wide geographical distribution, a dynamically changing environment, complex interdependencies between multiple components, operational criticality and uncertainty being characteristic of railway transportation, human resolutions are inconsistent, scale-inefficient and potentially infeasible with deadlocks. We present a multi-agent system (MAS) model for dynamic and real-time rescheduling (DRR) of bi-directional railway traffic on a single track in this paper. A computational framework to dynamically dispatch the disrupted trains in real-time, based on instantaneous system parameters and to reschedule conflicting trains with inherent deadlock avoidance is incorporated in the agents’ model. A learning architecture is implemented as a proof-of concept to resolve disruptions quickly and to enhance autonomy. The model is evaluated against integer optimal solutions generated by a Mixed-Integer Linear Programming (MILP) model using realistic data. Detailed discussions on architecture, implementation using JADE (Java Agent DEvelopment) toolkit, experimental results, performance analysis, evaluation of the model, insights and limitations are reported. The numerical performance measures of the model are total weighted delay of all trains at their destination terminals and computational time for resolution. The distinguishing research contributions in this paper are a MAS architecture for railway rescheduling, dynamic dispatch priority assignment using bidding and a learning procedure that enhances autonomy. [ABSTRACT FROM AUTHOR]

With the rapid advance of e-learning, the online peer help is playing increasingly important role. This paper explores the application of MAS to an online peer help system (MAPS). In the design phase, the architecture of MAPS is proposed, which consists of a set of agents including the personal agent, the course agent, the diagnosis agent, the DF agent and the communication agent. Through cooperation and negotiation, these agents are able to provide just-in-time and personalized peer help service on demand. In particular, it makes easy to perform such tasks as registering, searching and subscribing help services in a flexible fashion in MAPS. To clearly dem-onstrate the interactivity and message passing among agents, an UML sequence diagram is used to illustrate the peer help process. On this basis, the agent modeling approach is also discussed. In the phase of implementation, the JADE based agent behavior model was described in detail and the imple-mentation platform was also proposed. In the end, a demon-stration is used to exhibit the feasibility and reasonability of the proposed model and approach. [ABSTRACT FROM AUTHOR]

Abstract: Researches on Ambient Intelligent and Ubiquitous Computing using wireless technologies have increased in the last years. In this work, we review several scenarios to define a multi-agent architecture that support the information needs of these new technologies, for heterogeneous domain. Our contribution consists of designing in a methodological way a Context Aware System (involving location services) using agents that can be used in very different domains. We describe all the steps followed in the design of the agent system. We apply a hybridizing methodology between GAIA and AUML. Additionally we propose a way to compare different agent architectures for Context Aware System using agent interactions. So, in this paper, we describe the assignment of weight values to agents interaction in two different MAS architectures for Context Aware problems solving different scenarios inspired in FIPA standard negotiation protocols. [Copyright &y& Elsevier]

This article introduces the notion of environment programming in software multi-agent systems (MAS) and describes a concrete computational and programming model based on the artifact abstraction and implemented by the CArtAgO framework. Environment programming accounts for conceiving the computational environment where agents are situated as a first-class abstraction for programming MAS, namely a part of the system that can be designed and programmed-aside to agents-to encapsulate functionalities that will be exploited by agents at runtime. From a programming and software engineering perspective, this is meant to improve the modularity, extensibility and reusability of the MAS as a software system. By adopting the A&A meta-model, we consider environments populated by a dynamic set of computational entities called artifacts, collected in workspaces. From the agent viewpoint, artifacts are first-class entities of their environment, representing resources and tools that they can dynamically instantiate, share and use to support individual and collective activities. From the MAS programmer viewpoint, artifacts are a first-class abstraction to shape and program functional environments that agents will exploit at runtime, including functionalities that concern agent interaction, coordination, organisation, and the interaction with the external environment. The article includes a description of the main concepts concerning artifact-based environments and related CArtAgO technology, as well as an overview of their application in MAS programming. [ABSTRACT FROM AUTHOR]

Abstract: The objective of the work undertaken here is to endow an agent-oriented methodology with a semi-automatic tool for helping designers when drawing up the agents composing an adaptive multi-agent system (AMAS). This tool acts as a guide for enabling designers to influence the emergent global behaviour of an AMAS by acting on the local behaviour of its cooperative agents. The preliminary approach proposed in this article can be seen as a feasibility study aiming at developing a textual guide by considering the principles of the AMAS theory. Simulation of the behaviour of healthy and cancerous cells is used as a base for this study. [ABSTRACT FROM AUTHOR]

Abstract: The development of MAS can be facilitated with the introduction of simulations into the development process. The integration of simulations has been addressed by some agent oriented methodologies, generally defining mappings from the original Multi-Agent specification to concrete simulators like Repast or Sesame. This paper contributes with a deeper integration where the methodology becomes a generator of ad hoc simulators for the MAS under development. This is possible with the aid of Model Driven Engineering principles which derives executable Multi-Agent Systems automatically from a Multi-Agent System specification. [ABSTRACT FROM AUTHOR]

Interaction is at the core of multi-agent systems. We use agent environment as a general term to denote the medium for agent interaction. Over the last years, the agent environment has been subject of active research. In this paper, we reflect on the role of the agent environment in multi-agent systems from a middleware perspective. Our study yields the following observations: (1) multi-agent system engineers consider distributed middleware (RMI, CORBA, etc.) as the basic platform for developing multi-agent systems, (2) common middleware services (security, persistency, etc.) are only minimally considered in multi-agent systems, (3) domain-specific middleware for multi-agent systems such as communication services and support for stigmergic coordination are typically developed as stand-alone services and as such difficult to compose with other services. From these observations, we derive a number of challenges for research on environments in multi-agent systems: (1) to amplify reuse, application-specific services should be further consolidated into domain-specific services, (2) the problem of integration must be tackled, i.e. horizontal integration among domain-specific services for multi-agent systems, and vertical integration of domain-specific services upwards with the agents, and downwards with the common middleware services and the underlying distributed platform, (3) to support dynamic changing requirements of the system at hand, flexible composition and dynamic adaptation of services must be supported by the agent environment. [ABSTRACT FROM AUTHOR]

Adaptivity is very often an important goal for software systems. This paper reviews existing approaches to achieving adaptivity in object oriented systems, particularly those using design patterns, and concludes that there are further opportunities for improving adaptivity in agent systems. The approach described proposes that agents should be coupled with the environment, rules and laws about agent behaviour being externalised in a continuously re-configurable knowledge repository. Tools have been implemented to support the re-configuration. Once new requirements are specified by business experts via the tools, the system automatically adapts its behaviour in the environment, without additional effort from developers. This novel approach pulls together a knowledgebase, configuration tools, and business experts as an integral environment through which the MAS achieves re-configurability ranging from overall infrastructure to individual policy sets. This fosters cost effective software evolution because much of the effort resulting from changes to business strategies and collaborations can be shifted from developers to customers, code change not being required since the environment maintains the dynamics instead. [ABSTRACT FROM AUTHOR]

Recent research in the multi-agent systems field has highlighted the relevance of complex interaction models such as multi-party communication and context awareness. Nevertheless, there are no generic interaction model and infrastructure that enable to apply them in a standardized way. Emerging as a first-order abstraction, the environment, in the sense of a common medium for the agents, is a suitable paradigm to support these new interaction models. We present an operational model called Environment as Active Support of Interaction, that enables each agent to actively modify the environment according to its interaction needs. This model provides a suitable framework for the regulation of MAS interactions, and priority policies are given to manage the rules. An algorithm is proposed and assessed with an example stemming from the ambient intelligence domain. [ABSTRACT FROM AUTHOR]

The Facility Location Problem (FLP) requires locating facilities in order to optimize some performance criteria. This problem occurs in many practical settings where facilities provide a service, such as the location of plants, bus-stops, fire stations, etc. Particularly, we deal with the continuous version of location problem where facilities have to be located in an Euclidean plane. This paper contributes to research on location problems by exploring a new approach based on reactive multiagent systems. The proposed model relies on a set of agents situated in a common environment which interact and attempt to reach a global optimization goal. The interactions between agents and their environment, which are based on the artificial potential fields approach, allow to locally optimize the agent’s locations. The optimization of the whole system is the outcome of a process of agents self-organization. Then, we present how the model can be extended to the multi-level version of the location problem. Finally, the approach is evaluated to check its relevance. These evaluations concern both presented versions of the location problem. [ABSTRACT FROM AUTHOR]

The key role of environment as a first-class abstraction in the engineering of MAS (multi-agent systems) is today generally acknowledged in the MAS community. However, the support for the notion of environment in today AOSE (agent-oriented software engineering) methodologies is still either absent, weak, or incomplete at best. In this paper we first review, classify, and compare existing AOSE methodologies according to their support for the notion of MAS environment. Then we suggest a general approach for extending existing AOSE methodologies toward full environment support. [ABSTRACT FROM AUTHOR]

Advances in network and distributed technology has revolutionized the advent of multi-systems. Nowadays, agent technology has been applied in revising and restructuring the complex software systems. Trust plays a key role in multi-agent systems as agents will be representing or acting on behalf of users or owners with different goals and motivations. Tasks are delegated to software agents that achieve their common goals based on interaction among themselves. Current trust models focus on the limited aspect of stakeholders trust in multi-agent systems; for example security issues of the entities involved in system while ignoring the other issues such as knowledgeability, usability, persistency, accessibility, performance, collaboration, realism and integrity. This paper identifies the quality attributes of Multi-agent system, which foster the stakeholders trust in the system and hence establishes the multifaceted definition of trust in MAS. Building trust from the quality attributes would encourage the developer to induce these quality attributes in the MAS development life cycle and produce a system whose foundation will be the stakeholders trust. This paper also prioritizes the quality attributes of MAS in order of their impact on stakeholders' trust. [ABSTRACT FROM AUTHOR]

Agent communication languages (ACLs) should allow the developer to adopt human-like communication mechanisms in agent programming, facilitating the development of distributed protocols in multi-agent systems (MASs). However, to implement robust protocols, ACLs should provide a way to deal with the failures of agents, as MASs are prone to the same failures that can occur in any distributed software system. In this paper, we address this issue showing how an asynchronous ACL that provides high-level mechanisms to deal with crash failures of agents can be effectively used to specify fault tolerant protocols. [ABSTRACT FROM AUTHOR]

In this article, we discuss how to shape a MAS infrastructure to support an agent-oriented, role-based access control model (RBAC-MAS). First, we introduce the RBAC model, and show how it can be extended to capture the essential features of agent systems. Then, we extrapolate the core requirements of an infrastructure for RBAC-MAS, and depict a possible approach based on ACCs (agent coordination contexts). The conceptual framework for an RBAC-MAS infrastructure exploiting ACCs is subsequently formalized through a process-algebraic description of the main infrastructure entities: This is meant to serve as a formal specification of both the infrastructure and the language for expressing roles, operations, and policies in RBAC-MAS. [ABSTRACT FROM AUTHOR]

Abstract  Recent research on highly distributed control methods for complex systems have produced a series of philosophies based on negotiation, that bring together process engineering with computer science. Among these control philosophies, the ones based on multi-agent systems (MAS) have become especially relevant. Furthermore, among a number of MAS implementations, those that use different types of agents at different conceptual/managerial levels are commonly applied. However, these MAS models have the drawback of an excessive dependence on up-to-date information about the products and other elements that move within the system. A new technology has come out that can help solve this problem: radio-frequency identification enhanced information management systems (RFID-IMS). One of these is Auto-ID/EPCglobal technology. This paper shows how a MAS model can be used for controlling a machining system incorporating RFID-IMS technology. The resulting system becomes an RFID-enhanced intelligent manufacturing system (RFID-IMS II). [ABSTRACT FROM AUTHOR]

An architecture for building up agile collaborative manufacturing systems (ACMS), which is based on common object request broker architecture (CORBA) and multi-agent system (MAS) paradigm, is proposed in the current paper. First, the diverse manufacturing resources, which may be heterogeneous and physically distributed, are MAS-based agentified and CORBA-based encapsulated as the resource agents. Second, the source agents are registered at the system manager agent (SMA) as member agents and subsequently integrated under the proposed architecture to form an ACMS. Third, the member agents communicate and interact with each other to conduct collaborative manufacturing by means of agent interoperation and human-machine interaction. In order to validate the methodology, an experimental system is developed, where several heterogeneous manufacturing resources are well-integrated via their agents in a plug-and-play manner to establish an ACMS prototype. The experiments demonstrate that the proposed architecture, characterized by distribution and openness, provides a feasible solution for developing ACMS, where integratability, reconfigurability, flexibility and agility are achieved. [ABSTRACT FROM AUTHOR]

This paper presents a new approach of using multi-agent system (MAS) to build a software engineering environment to support unit testing process for extreme programming (XP). The MAS reference model by Foundation for Intelligent Physical Agents (FIPA) is extended in this paper. The extended components are: 1) agent roles, 2) storage components, and 3) ontology. The FIPA-complied Java Agent Development framework (JADE) agent platform is used in implementation. The Darpa agent mark-up language (DAML) is used as process data format, including ontology. And, JENA API by Hewlett-Packard (HP) is used to store DAML ontology. Further, examples are given to show feasibility of this approach. The expected benefits of this agent-based approach are to: 1) Improve environment flexibility and reliability, 2) Facilitate XP practices, and 3) Use DAML format that is suitable for agents. [ABSTRACT FROM AUTHOR]

Abstract A methodology based on topology theory to model a semantic network for a collaborative system is given. This framework is used to support the creation of a semantic network and to define the associated intelligent cooperative system. Our methodology is illustrated via a set of agents whose knowledge-base is a semantic network. By a series of functions applied on a base of entities, issued from the application domain, a family of sets are synthesized with their subspaces correlated. The resultant subspaces and their relations form a network of elementary and complex concepts that can be naturally represented with the IDEF1x language. A prototype Multi-Agent System (MAS), set up with the Zeus platform,1 was developed for the Process Plan domain, which was used as a case study. Full correspondence among the subspaces, the semantic network IDEF1x information model and the MAS implementation is obtained by employing this framework. [ABSTRACT FROM AUTHOR]