A cooperative control model for multiagent-based material handling systems

This paper presents an Artificial Immune System (AIS)-based model for cooperative control of multiagent systems. This cooperative control model describes collective behaviors of autonomous agents, known as the AIS agents that are exemplified by the regulated activities performed by individual agents under the computation paradigm of Artificial Immune System. The regulations and emergence of agent behaviors are derived from the immune threshold measures that determine those activities performed by the AIS agents at an individual level. These threshold measures together with the collective behavioral model defined the cooperative control of the AIS-based control framework under which AIS agents behave and act strategically according to the changing environment. The cooperative control model is presented under the three domains, namely exploration, achievement and cooperation domains where AIS agents operate. In this research, we implemented the proposed cooperative control model with a case study of automated material handling with a group of AIS agents that cooperate to achieve the defined tasks.     

A multiagent-based model for pedestrian simulation in subway stations

Multiple components such as complicated station environment, heterogeneous pedestrians and diverse interactions make it difficult to realize an effective pedestrian simulation in subway stations. A multiagent-based model is proposed on the basis of the metamodel proposed by Béhé, which includes the subway station environment abstraction model, three-level pedestrian agent model and interactive rule base. The first term incorporates some notions to satisfy the specific modeling demands of subway stations and uses the object-oriented modeling method to realize a normative, extensible and flexible simulation environment building platform. The second integrates the three levels of NOMAD model and takes staged pedestrian behaviors into account, which works well for simulating real pedestrian behaviors in subway stations. The third realizes various and staged interactions correctly and automatically. Finally, a case study of Ping'anli Station in Beijing Subway is presented and three comparison issues are introduced to validate the effectiveness of our models.     

Scheduling mobile collaborating workforce for multiple urgent events

Despite the advancement of wireless technologies that allows collaboration at different places, under emergencies, professionals are often still required to arrive at the scene to carry out critical tasks. Under many practical constraints, how to schedule mobile collaborating workforce for urgent event requirements becomes a challenging problem. In this paper, we study the optimal mobile workforce assignment problems for multiple events and propose an efficient algorithm to find an optimal workforce arrangement with respect to quick response under qualification and location constraints. A practical example is given to illustrate how our method works. We also study the exception case where there are not enough qualified users. We allow a user to take on multiple qualified tasks previously assigned to different users. But each person is restricted within one event location so as to reduce traffic transfer between different places for the quick response purpose. We analyze the computational complexity of the problem of finding an optimal assignment of mobile workforce under such restraints and solve it by means of integer linear programming.     

A multiagent-based complex systems approach for dynamic negotiation mechanism in virtual enterprise

Nowadays a sophisticated match-making mechanism is necessary for appropriate collaborations in virtual enterprise (VE). Virtual market based match-making operation enables effective partner search in terms of products allocation by distributing the scheduled resources according to the market prices, which define common scale of value across the various products. We formulate the VE match-making model as discrete resource allocation problem, and propose a complex market-oriented programming framework based on the economics of complex systems. Three types of heterogeneous agents are defined in the complex virtual market. It is described that their interactions with micro behaviour emerge a macro order of the virtual market, and the clearing price dynamism can be analysed in economic terms. The applicability of the framework into resource allocation problem for VE is also discussed.     

An intelligent Quality of Service brokering model for e-commerce

A fuzzy logic based Quality of Service (QoS) brokering model for e-commerce to manage system and network resources is presented in this study. This model takes into consideration limited bandwidth between clients and their Internet Service Providers; and similarly the client’s system capabilities. The QoS brokering system was modelled, developed, and simulated using Matlab 7.0. Its performance was evaluated using two QoS performance metrics namely the response time and the throughput. The proposed QoS brokering model is simple to implement as well as robust due to the nature of fuzzy controller. Simulation results of the proposed QoS brokering system demonstrate the effectiveness of the model in managing resources optimally and also improving the user-perceived QoS of e-commerce application.     

The mobile groups approach for the coordination of mobile agents

We present the concept of mobile groups as a basic mechanism for the reliable coordination of mobile agents. Analogously to traditional group systems, mobile groups also provide message delivery guarantees and virtual synchrony. Furthermore, they make agent mobility not only visible for the group, but also consistently ordered with other group actions (such as crashes, joins, leaves, and other migrations). The mobile groups approach represents a novel mobility support mechanism, which can be used to handle reliability of mobile agents required at both, the application and system level (e.g., for coordinating distributed agents and for reliable agent migration, respectively). In this paper, we discuss the motivations for the mobile groups approach, formally define their properties, and present a membership protocol for such groups. We also discuss some implementation issues and related performance data, and present the advantages of mobile groups against mechanisms commonly employed for the coordination of mobile agents.     

An ontology-based metamodel for multiagent-based simulations

Multiagent-based simulations enable us to validate different use-case scenarios in a lot of application domains. The idea is to develop a realistic virtual environment to test particular domain-specific procedures. This paper presents our general framework for interactive multiagent-based simulations in virtual environments. The major contribution of this paper is the integration of the notion of ontology as a core element to the design process of a behavioral simulation. The proposed metamodel describes the concepts of a multiagent simulation using situated agents moving in a semantically enriched 3D environment. The agents perceive the geometric and semantic data in the surrounding environment. They are also able to act in this environment by using high-level actions, which are described by the ontology of the environment. The concepts relating to the environment, the agent, and the entire simulation models are presented. Additionally, guidelines are given to exploit the simulation results to characterize the agents. Finally, a simple application of the metamodel is presented, based upon the use of Industry Foundation Classes.     

A model checking-based approach for security policy verification of mobile systems

This article describes an approach for the automated verification of mobile systems. Mobile systems are characterized by the explicit notion of location (e.g., sites where they run) and the ability to execute at different locations, yielding a number of security issues. To this aim, we formalize mobile systems as Labeled Kripke Structures, encapsulating the notion of location net that describes the hierarchical nesting of the threads constituting the system. Then, we formalize a generic security-policy specification language that includes rules for expressing and manipulating the code location. In contrast to many other approaches, our technique supports both access control and information flow specification. We developed a prototype framework for model checking of mobile systems. It works directly on the program code (in contrast to most traditional process-algebraic approaches that can model only limited details of mobile systems) and uses abstraction-refinement techniques, based also on location abstractions, to manage the program state space. We experimented with a number of mobile code benchmarks by verifying various security policies. The experimental results demonstrate the validity of the proposed mobile system modeling and policy specification formalisms and highlight the advantages of the model checking-based approach, which combines the validation of security properties with other checks, such as the validation of buffer overflows.     

Ontology-driven visualization system for semantic searching

Technical manuals are very diverse, ranging from software to commodities, general instructions and technical manuals that deal with specific domains such as mechanical maintenance. Due to the vast amount of documentation, finding the information is a tedious and time consuming task, especially for the mechanics. It is also difficult to grasp relationships among contents in manuals. Many researchers have adopted ontology to solve these problems and semantically represent contents of manuals. However, if ontology becomes very large and complex, it is not easy to work with ontology. Visualization has been an effective way to grasp and manipulate ontology. In this research, we propose a new ontology model to represent and retrieve contents from the manuals. We have also designed a visualization system based on our proposed ontology. In order to model the ontology, we have analyzed aircraft maintenance process, extracted the concepts and defined relationships between concepts. After modeling ontology schema, all instances of ontology are created by instance creator. From here, raw data of maintenance manuals are preprocessed to well-formed format. Next, we create a set of rule mapping well-formed document and ontology schema. For the Component class, instance creator uses a classifier to separate all parts into Component and Primitive part class. If population task is complete, validity of data for created instances will be checked by JENA engine. The inference process will create inferred triples based on the ontology schema, and then the triples are saved into a triple repository. Our system then will use this triples repository to search necessary information and visualize the search results. We use the Prefuse toolkit to visualize the search results. With this, the mechanics can intuitively grasp the relationship between maintenance manuals using the provided information. This will allow the mechanics to easily obtain information for given tasks, reduce their time to search related information and understand the information through visualization.     

Soft computing techniques for web services brokering

To enhance and improve the interoperability of meteorological Web Services, we are currently developing an Integrated Web Services Brokering System (IWB). IWB uses a case-based classifier to automatically discover Web Services. In this paper, we explore the use of rough set techniques for selecting features prior to classification. We demonstrate the effectiveness of this feature technique by comparing it with a leading non-rough set (Information Gain) feature selection technique.     

An embeddable mobile agent platform supporting runtime code mobility,interaction and coordination of mobile agents and host systems

Agent technology is emerging as an important concept for the development of distributed complex systems. A number of mobile agent systems have been developed in the last decade. However, most of them were developed to support only Java mobile agents. In order to provide distributed applications with code mobility, this article presents a library, the Mobile-C library, that allows a mobile agent platform, Mobile-C, to be embeddable in an application to support mobile C/C++ codes carried by mobile agents. Mobile-C uses a C/C++ interpreter as its Agent Execution Engine (AEE). Through the Mobile-C library, Mobile-C can be embedded into an application to support mobile C/C++ codes carried by mobile agents. Using mobile C/C++ codes, it is easy to interface a variety of low-level hardware devices and legacy systems. Through the Mobile-C library, Mobile-C can run on heterogeneous platforms with various operating systems. The Mobile-C library has a small footprint to meet the stringent memory capacity for applications in mechatronic and embedded systems. The Mobile-C library contains different categories of Application Programming Interfaces (APIs) in both binary and agent spaces to facilitate the design of mobile agent based applications. In addition, a rich set of existing APIs for the C/C++ interpreter employed as the AEE allows an application to have complete information and control over the mobile C/C++ codes residing in Mobile-C. With the synchronization mechanism provided by the Mobile-C library for both binary and agent spaces, simultaneous processes across both spaces can be coordinated to get correct runtime order and avoid unexpected race condition. The study of performance comparisons indicates that Mobile-C is about two times faster than JADE in agent migration. The application of the Mobile-C library is illustrated by dynamic runtime control of a mobile robot’s behavior using mobile agents.     

A transaction model and multiversion concurrency control for mobile database systems

Transaction management on Mobile Database Systems (MDS) has to cope with a number of constraints such as limited bandwidth, low processing power, unreliable communication, and mobility etc. As a result of these constraints, traditional concurrency control mechanisms are unable to manage transactional activities to maintain availability. Innovative transaction execution schemes and concurrency control mechanisms are therefore required to exploit the full potential of MDS. In this paper, we report our investigation on a multi-versions transaction processing approach and a deadlock-free concurrency control mechanism based on multiversion two-phase locking scheme integrated with a timestamp approach. We study the behavior of the proposed model with a simulation study in a MDS environment. We have compared our schemes using a reference model to argue that such a performance comparison helps to show the superiority of our model over others. Experimental results demonstrate that our model provide significantly higher throughput by improving degree of concurrency, by reducing transaction wait time, and by minimizing restarts and aborts.     

Energy-saving compilation for mobile systems

This paper presents an algorithm for optimization of programs at the compilation stage that analyzes execution of various program segments at available processor frequencies and selects an energy-effective schedule of frequencies with regard to the constraints of the arising additional time of operation. This algorithm is complemented by an operating-system manager that controls setting of a desired processor mode and resolves conflicts in multi-program environment.     

MARS: a programmable coordination architecture for mobile agents

Mobile agents offer much promise, but agent mobility and Internet openness make coordination more difficult. Mobile Agent Reactive Spaces (MARS), a Linda-like coordination architecture with programming features, can handle a heterogeneous network while still allowing simple and flexible application design     

Movement coordination for single-track robot systems

We consider problems associated with the coordination of movement within a multiple-robot system in which all motion is restricted to a single track. Our objective is to minimize the reconfiguration time, that is, the total time required to move a collection of robots from an initial to a goal configuration. We show that various models give rise to a wide range of problem complexities. For these problems we design and analyze optimization and approximation strategies.     

Location management techniques for mobile systems

Locating users in mobile environment is an essential problem in PCS that becomes more challenging as the network size increases and the user population grows. In third generation mobile systems, the signaling traffic and processing overhead of location updates is expected to grow tremendously leading to poor performance. Therefore location management schemes should aim at reducing the cost of updates. Yet, the lookup delay should be kept minimum. This paper aims at classifying the various approaches used for location management of mobile users by grouping them into two main categories. The first category comprises techniques that focused on reducing the cost of looking up a user and adjusted the update process accordingly. These are classified into replication, caching and selective paging techniques. The second category consists of techniques that focused on reducing the cost of updates and maneuvered the update policy to reduce the lookup cost by informing the system with the maximum possible information about user's mobility. This could be achieved by the use of statistic collection, estimation or prediction processes. We classify those schemes into three main classes: schemes based on forwarding pointers, learning-based schemes and prediction-based schemes. By investigating the technical significance of each class a new direction for future research is proposed which favors the second category of location techniques and emphasis the importance of adopting suitable learning and prediction techniques to optimize the overall location cost.