In this paper, we study the rekeying issue in IEEE 802.16e WiMAX networks. The existing rekeying scheme the Multicast and Broadcast Rekeying Algorithm (MBRA) unicasts new keys to each subscriber station (SS). This scheme does not scale well since it incurs large communication overheads when the number of SSs increase. In our work, first we propose a general tree-based rekeying scheme, which is ...

This paper presents an effective way of modeling complex systems through identified functioning modes. In the proposed approach, the integration of monitoring in the manufacturing system is facilitated by the development of a generic model. The aim is to propose a monitoring system able of absorbing internal degradation of any variables and ensuring the continuity of the service. The outline of...

The main focus of this work was the simulation and optimization of a BIPV-façade-system configuration through the development of simulations using the software ”TRNSYS”. First, several limitations and constraints within the TRNSYS framework needed to be solved to develop a reliable simulation environment. Various parameters were detected which are influencing the temperature distribution over a...

The design of reconngurable systems is a hard task due to a huge amount of optimization trade-oos and constraints. Deeciencies at the higher level of conceptual decisions may result in critical bottlenecks of the system implementation. This paper explores the design space and performance evaluation criteria of reconngurable systems and introduces a concept for an evaluation framework based on t...

For many emerging applications and environments, information systems designers and implementers must consider the tradeo s between e ciency and the quality of query answers. This exibility, while allowing numerous opportunities for optimization, complicates the development of various system components and their performance evaluation. In this short paper, we rst outline the issues that arise in...

High-resolution satellite imagery provides an important new data source for building extraction. We demonstrate an integrated strategy for identifying buildings in 1-meter resolution satellite imagery of urban areas. Buildings are extracted using structural, contextual, and spectral information. First, a series of geodesic opening and closing operations are used to build a differential morpholo...

Traffic evacuation is one of the most challenging problems in a mega city due to crowded road conditions. This study focuses on developing a traffic evacuation model with decision-making capability. The model basically consists of two modules. The first one is a decision-making support module which runs very fast and provides short-forecast. The second one is a simulation module, which is used ...

The development of performance measurement and analysis techniques and tools for high-performance parallel and distributed systems has made it possible to capture a wealth of data about application and system performance behavior. These data embody the effects of interacting, performance factors found in the program, its algorithms, the architecture and hardware, and the system software, whose ...

It is well known that the complex system operation requires the use of new scientific tools and computer simulation. This paper presents a modular approach for modeling and analysis of the complex systems (in communication or transport systems area) using Hybrid Petri nets. The performance evaluation of the hybrid model is made by a simulation methodology that allows building up various functio...

The overall efficiency, reliability, and availability of a firewall is crucial in enforcing and administrating security, especially when the network is under attack. The continuous growth of the Internet, coupled with the increasing sophistication of the attacks, is placing stringent demands on firewall performance. These challenges require new designs, architecture and algorithms to optimize f...