Volume1, Number3, 2000


 

 

Title:

A solution for a Deterministic QoS in multimedia Systems

Author:

Laurent George, Dana Marinca, PascaleMinet

Abstract:

We are interested in multimedia systems providing VoD (Video on Demand) and NvoD (Near Video on Demand) with a deterministic Quality of Service (QoS). The first aim of this paper is to define and guarantee the QoS suitable for multimedia systems. We consider sporadic traffics composed of different unicast or multicast flows. The second  aim is to propose an admission control ensuring a deterministic guarantee of QoS. The QoS parameters of accepted traffics are met, as long as traffics are in conformance to their specification. This admission control optimizes the guaranteed sojourn times in each visited node to accept more traffics without compromising the end-to-end deadlines of already accepted traffics. We show how to admit a new flow when each visited node cancels the received jitter and schedules flows according to NP-EDF. The complexity of the admission control is shown to be pseudo-polynomial.

 

 

Title:

Self-stabilizing Distributed Spanning Tree and Leader Election Algorithm

Author:

Ivan Lavallee

Abstract:

In the following we show how to design an autoadaptative and self stabilizing distributed algorithm. The meaning of  “adaptativity” is that the algorithm accepts the topological changes occurring in the network. This authorizes the algorithm to work on dynamical networks or to support any crash or failure of sites or communication lines. The algorithm is also self stabilizing. The background concepts are from our previous works on the Spanning Tree distributed algorithms (see [14,15]) on anonymous or identified networks. We suppose here the link register model for processes’ communications. We show how to obtain a Spanning Tree distributed algorithm despite topological variations and corruptions in the contents of variables. This algorithm supposes that there only is tamed daemon but we have showed in [12] how to exorcize daemons in a link register environment. The algorithm simultaneously elects a process. The algorithm is symmetrical. That is to say that any process executes the same code. The only change is the process  identifier. There is no a priori preferential process.

 

 

Title:

Implementation of a Self-Organising Fuzzy Sliding-Mode Controller Using a Multi-Thread Architecture

Author:

Wei Huang, Warren Jasper, Adward Grant, Gordon Lee

Abstract:

Modeling and control of a nonlinear system with time delays is a challenging problem, particularly when the system has unknown parameters. The problem can be partitioned into a parameter identification component and a nonlinear control formulation. Each of these tasks require an efficient computational approach, particularly when the system must be modeled and controlled on-line in real-time. This paper presents a new method for nonlinear control using a self-organizing fuzzy sliding mode architecture. Parameter identification is performed on-line using a recursive least-squares approach. To make the algorithm more efficient for real-time implementation, particularly since the approach requires simultaneous tasking, a multi-thread structure is employed. In order to analyze the method, the parameter-identifier/self-organizing fuzzy sliding mode controller is applied to a dyeing process which contains several of the nonlinear effects (time delays, complex dynamics, uncertainties) that may be faced in real world applications. Results of the control architecture using the multi-thread computing for a dyeing process illustrate the efficiency of this approach.

 

 

Title:

Composing Fair Objects

Author:

Geoff W. Hamilton

Abstract:

When specifying large systems, we would like to be able to specify small components independently, and to be able to compose them in such a way that their specified properties are preserved. The concept of a fair object, which incorporates the specification of both safety and liveness properties, has previously been proposed as a suitable such unit of specification. In this paper, we provide a more formal treatment of fair objects. We show that the liveness properties of fair objects are often not preserved under composition, and we define a simple test to determine whether this is the case. We then show how liveness properties can be restored in some cases when they are broken, through the addition of fairness constrains.

 

 

Title:

A FIPA Compliant Agent Platform for Federated Information Systems

Author:

Maurizio Panti, Loris Penserini, Luca Spalazzi, Sal Valenti

Abstract:

A Territorial Framing Plan (TFP) is an open and cooperative system, outlining a reference model that allows describing social, economical and cultural phenomena coming into the plan and their actual manifestations. In the light of current research insights and available technology, it appears that a TFP may be adequately modeled through a Federated Information System approach. In this paper we will discuss the implementation of a platform based on software agents for federated information systems. The platform has been developed trying to fulfill the FIPA specifications with special emphasis on: portability, use of standard protocols both for intra and extra platform communication, autonomy and dinamicity, support of cooperation among agents.

 

 

Title:

Foundational Aspects of Agent Coordination

Author:

Bertil Ekdahl

Abstract:

Many papers in multiagent systems concern the coordination of computerized agents, who are mutually connected and have the ability to transmit signals to each other as a way of coordination. Such agents are regarded as communicating devices and communication is the means of coordination. However, communication, in the sense of making something known or to exchange information, news, ideas, etc., with somebody, is a linguistic activity, which involves understanding, that is, semantics, and must be carried out between parts that have the ability to transmit ideas, i.e. concept.

     Using the linguistic complementarity as a general notion of explanation I analyze the concept of communication in this context, and conclude that communication between computerized agents is restricted to the kind of signaling that are meaningful between formal systems. The point stressed here is that one should very carefully distinguish between communication in its human sense and when this concept is used in the context of computerized agents restricted to using signals with fixed interpretation.