Abstract:

Distributed and Complex Systems are more and more vulnerable to failures on account of their growing complexity and distribution. This problem motivates the need for a fault tolerance mechanism in such systems. Hence, we focus on two areas: (1) in a Wide Area Network, and (2) in a Local Area Network.
Our paper highlights these two approaches. Indeed, the first part focuses on the problem of reliable duplication mechanism on grid environments (WAN) while the second part consists on the development of a fault tolerant distributed system in a LAN based on fuzzy cognitive maps, so to conceive a design of impact analysis and its development guaranteeing in times of answer by using the inference of the fuzzy cognitive maps.
As a first task, we define a new group communication system extending the FSR protocol which is developed by the INRIA/EPFL. Because of his interesting results in a cluster of homogenous machines, this work consists on adapting this system to the grid environments. Whereas, the following part of our paper, shows architecture of a fault-tolerant distributed system. So in order to reach our objective and achieve our research, this is our planning in this part:

• What is a group communication system?
• The group communication system FSR([ 2])
• Introducing our group communication system for grid environment denoted FSRG.
• The simulation on JSim to evaluate the performance of FSRG.

Then, as a second task, we concept a model of impact analysis of engine of rules in an environment object in which objects and their links of impact (CIs: elementary components of the information system contributing to the delivery of a service), are neither defined nor ordered and the real time restoration of analysis of impact results and presentation according to the various orchestrated processes. Thus our role is to conceive a design of impact analysis and its development guaranteeing in times of answer by using the inference of the fuzzy cognitive maps.

Abstract:

This paper presents a varactor square ring tunable bandpass filter used as a phase shifter. This proposed structure is based on coupled Micro-strip resonator. We have used Momentum software of ADS-Agilent for the optimization and simulation of our circuit. A good result was obtained; in terms of insertion loss (0.31dB−0.17dB) over tuning range and bandwidth of (450MHz−640MHz). We compute a fractional bandwidth between 19% and 25% for different value of varactor capacitance. We have obtained also a good dynamic range of phase shifting about 90° at operating frequency.

Abstract:

In This work, the design, fabrication, and measurement of a tunable microwave tapered phase shifter is presented. A mathematical model of matching tapered transmission line, based on resolution of differential equations is investigated. We noticed a wideband operating frequency from 1.0GHz to 3.0GHz with average insertion loss lower than 1.0dB and return loss is about 10dB. A dynamic range of phase shift at 2.4GHz is about 100°. An excellent agreement between simulation results and measurement is obtained, that confirm the validity of our theoretical model.