A cooperative information system to support multi-expert systems development

The development of a multi-expert system (MES) is obviously a team project. This paper shows how database technology can actively and cooperatively support the development and design of a multi-expert system. The proposed solution is based on an Active and Deductive DataBase (ADDB). An extensional database records and maintains information about the project and its evolution. An intensional database, defined by a set of rules, coordinates and controls the activity of the different actors, and models relevant views on the project. This rule base can be fired automatically when an interesting event occurs and consequently either informs the members of the team concerned by this event (beginning of a new step, creation of a new product, modification of a knowledge base, etc.), or triggers another activity, or invokes other tools. This rule base can also be executed explicitly to provide its user (experts, developers, the project manager, etc.) with cooperative information concerning the project. This cooperative information improves the visibility and the intelligibility of the project and knowledge reuse.     

A generic approach to detect design patterns in model transformations using a string-matching algorithm

Software and Systems Modeling - Maintaining software artifacts is a complex and time-consuming task. Like any other program, model transformations are subject to maintenance. In a maintenance...     

Protocol Moderators as Active Middle-Agents in Multi-Agent Systems

Interaction protocols are widely recognized as an essential mechanism for coordination within multi-agent systems. There is thus a need for coordination models for specifying, validating, and implementing protocols, possibly open and concurrent, efficiently and reliably. This paper proposes such a model, which considers protocols as resources and each conversation among agents following the rules of a protocol as a well-identified process. To this end, a new kind of middle-agent, called Moderator, is introduced. A Moderator is in charge of monitoring a conversation so that it progresses according to the protocol rules, and provides agents with services to ease their involvement in the conversation. This model fits the organization-centered view of multi-agent systems as it strictly distinguishes the agent-level and the organization-level concerns with regard to interaction. In addition, the paper shows that this model is supported by a High-Level Petri Net language that covers all the steps of protocol engineering: design, validation, implementation. This paper presents this Moderator Coordination Model along four related dimensions: a conceptual model of protocols, a MAS architecture, a suitable modeling formalism, and an associated development process.     

Lack of correlation between the effects of transient exposure to glutamate and those of hypoxia/reoxygenation in immature neurons in vitro

To assess the influence of brain immaturity on the effects of oxygen deprivation and the participation of excitotoxicity, the consequences of a 6-h exposure to either hypoxia (95% N2/5% CO2) or 100 microM glutamate were studied in cultured fetal rat forebrain neurons taken at two maturational stages, i.e., 6 and 13 days in vitro. Cells were examined for their morphology, viability, energy metabolism reflected by 2-D-[3H]deoxyglucose uptake, and protein synthesis assessed by [3H]leucine incorporation. Apoptosis and necrosis were scored using the fluorescent dye 4,6-diamidino-2-phenylindole. Whereas 6-day-old neurons responded to a 6-h hypoxia by transient hypermetabolism, biphasic increase in protein synthesis, and cycloheximide-sensitive apoptotic death within 72 h postexposure, glutamate did not affect cell characteristics by the same time. In 13-day-old neurons, hypoxia induced both apoptosis (8.2%) and necrosis (22.3%). At this age, glutamate definitely reduced energy metabolism (26%) and protein synthesis (17%) by the end of exposure. The percentage of necrotic neurons reached 40.7%, but the rate of apoptosis was unchanged compared with controls. Therefore, excitotoxicity cannot account for hypoxia-induced injury in immature neurons, but its participation is suggested in older cells by the suppression of the necrotic component of hypoxia by glutamate receptor antagonists at 13 days.     

On finite damage: ductile fracture-damage evolution

The tensorial entities pertaining to the presence of a damage zone within a representative material sample are obtained from the micro-macro transition of kinematic quantities in finite deformation. It is shown that they reduce to a ‘small-damage’ tensor as the finite deformation measures reduce to their common infinitesimal counterpart.Based on an assumed local (microscopic) velocity field within a sample, the process of void growth from a spherical inclusion is then quantified by a tensorial damage evolution equation. This equation gives the rate of change of damage tensor as a function of the overall strain rate, actual damage state and some scale factor. The problem of oblate shape cavity growth in the direction of a higher (positive) overall strain component is examined.