In this work we consider the problem of pursuit evasion games (PEGs) where a group of pursuers is required to detect, chase and capture a group of evaders with the aid of a sensor network in minimum time. Differently from standards PEGs where the environment and the location of evaders is unknown and a probabilistic map is built based on the pursuer’s onboard sensors, here we consider a scenario where a sensor network, previously deployed in the region of concern, can detect the presence of moving vehicles and can relay this information to the pursuers. Here we propose a general framework for the design of a hierarchical control architecture that exploits the advantages of a sensor network by combining both centralized and decentralized real-time control algorithms. We also propose a coordination scheme for the pursuers to minimize the time-to-capture of all evaders. In particular, we focus on PEGs with sensor networks orbiting in space for artificial space debris detection and removal.

The Unified Modeling Language (UML) is fast becoming an industry standard for object-oriented modeling and analysis. Applying the UML to model, analyze and design dependable systems require methods and tools for model checking that are integrated with the UML and its support environment. Recent advances in model-checking technologies have led to the development of approaches and tools to check the correctness of security protocols as well as check the correctness properties (such as deadlock properties) of architectural abstractions of component based systems implementing specific styles of coordination. This paper focuses on use of a specific model-checking technology, SPIN, in model checking architectures specified using UML. In particular the paper develops an approach to check desired properties of a class of distributed component based software architectures characterized by indirect connection via mediators and shared space. The approach is demonstrated in the context of an architectural design implementing the NetBill protocol for e-commerce.

In mission critical applications of distributed information systems, autonomous information resources are coordinated to meet the information demands of client specific decision-support views. The current approach to view coordination relies on design-time trade-offs to select a static view coordination policy from a set of available policies. This approach is not robust and does not respond well in a dynamic environment with shared infrastructure, and dynamically changing missions, priorities, preferences, and constraints. This paper introduces, NAVCo, a negotiation-based adaptive view coordination approach that allows view coordination policies To be dynamically negotiated and adapted at run-time in response to dynamically changing conditions.

A major problem in requirements engineering is obtaining requirements that address the concerns of multiplestakeholders.An approach to such a problem is the Theory-W based Spiral Model.This paper focuses on the problem of developing a support system for such a model.In particular

A description is given of how information stored in databases can be used to support reasoning using an assumption-based reasoning system with truth maintenance. The basic notion behind this type of reasoning is that the problem solver can draw inferences on the basis of assumptions in the absence of information to the contrary. These inferences are nonmonotonic, in the sense they may be contradicted by update to the information base and hence lose their validity status. The objective is to describe some techniques for maintenance in databases to extend an assumption based truth maintenance system to make use of large amounts of data stored in databases. There are two levels of truth maintenance taking place in the system. Truth maintenance occurs at the level of the database and at the level of explicit facts derived or asserted. The focus is on the computational techniques that are necessary at the former level.>

This paper presents an approach to extending the relational system RTMS into one supporting a frame-based knowledge-representation system. A deductive front-end is used for extraction of implicit information from the explicit data stored in RTMS. The proposed extensions to the relational model include the relationships of aggregation and generalization, set-valued attributes, and virtual relations defined using axioms. We will present a query language that takes advantage of these extensions. A user can make a query against virtual relations as well as base relations. The queries can consist of new constructs introduced by the semantic front-end. The system is implemented on TI's Explorer Lisp Machine.