Electronically reconfigurable parasitic antenna array for pattern selectivity

Antenna arrays are commonly used to achieve high gains and beam steering, but they require complex feeding networks. For applications demanding moderate antenna gains (≃6 dB) and planar radiating structures, printed Yagi-Uda antennas can offer many advantages, but clearly, they cannot cover the whole azimuth plane. A symmetric structure made of two Yagi-Uda antennas with two active elements, a shared reflector and two directors of variable length is here presented and demonstrated to have switched beams that cover all the azimuth plane. By lengthening the physical lengths of the directors, they turn to act as reflectors: as a result, this antenna system has the ability to switch between broadside, bidirectional end-fire and two opposite end-fire patterns. The feeding is provided by a balanced parallel strip-slot line without the need for a balun section and thus reducing the overall size of the antenna. A modified design is also presented, obtained by adding a reflector board which allows for higher gains and focused radiation reconfigurability in the half-space. Simulated and measured results of both designs are reported showing good agreement. The antenna has a compact size, wideband characteristics and directive pattern reconfigurability

Nonlinear Control Systems Simulation Using Spreadsheets

In this paper, a method for simulating nonlinear control systems using spreadsheets is presented. Various nonlinear blocks are simulated using graphics and cell formulas, and are generated by clicking on specially developed toolbar buttons. These blocks can be connected to one another using a simple and intuitive procedure again based on graphics and toolbar buttons. A complete nonlinear system can thus be created by generating and connecting its constituting basic blocks, using the simple graphics interface provided. The corresponding data may then be entered in the familiar manner as illustrated, and finally the system can be simulated literally at the click of a button. Such a system can be analyzed by calculating its time response to any input signal or by using other methods such as phase-plane trajectories. The simulation is characterized by its availability, flexibility, and simplicity. The paper provides several examples to illustrate the simulation capabilities available. The first example considers a servo with a dead-zone and a saturation amplifier, the second illustrates the steps required to obtain a phase-plane trajectory, and the third example considers a nonlinear system having a PI controller and nonlinearity consisting of soft saturation. The final example illustrates a relay-controlled servo system

Reliability of Agents' Integration in Telecommunication Networks

International audienceMulti-agent Systems (MAS), which are composed of multiple intelligent agents have been used for a long time to solve problems related to online trading, disaster response, modeling social structures, and others. Recently, MAS have found its way into networking and telecommunication networks. This paper presents a number of tests that show the improvements gained in the performance of a Diffserv network after integrating a multi-agent system. The suggested DiffServ technique adopts the standard lowest metric routing path along with an agent's behavior able to help the different routers in finding and using other possible routes than the default one, even if the cost of these new paths is higher. The adopted network, based on an extension to the J-Sim simulation environment, is used to support integration of agents and multi-agent systems within a telecommunication network. Simulation shows that agents, especially cooperative agents, are able to increase the performance of a telecommunication network

Intelligent Features Within the J-Sim Simulation Environment

International audience; This paper presents our approach integrating a high level of intelligence within telecommunication networks. Artificial intelligence has proved its efficiency in resolving complex issues in different fields like air traffic control, robotics, and medical diagnosis. However its usage in telecommunication networks is still very moderated. The main objectives of our framework is to encourage the deployment of techniques characterized by a high level of intelligence – inspired from the artificial intelligence domain in networking. For this reason, we build an extension, with intelligent capabilities, to the J-Sim simulation environment. This extension proposes an intelligent package having the essential entities required for simulating intelligent features. Using this intelligent package and the abstract node model (INET) proposed by J-Sim for network simulations, it will be possible to test the efficiency of integrating intelligent techniques in networking. Document type: Part of book or chapter of boo

A Dual Simulation Environment for Simulating MAS in Telecommunication Networks

International audienceThis paper presents a dual simulation environment for simulating different type of telecommunication networks integrating intelligent agents. Agents are considered as advanced tools for resolving complex issues in networking based on intelligent and dynamic features. To test the efficiency of these proposals, new simulation environments, integrating both agents and network components, are required. In this paper we propose an extension with intelligent capabilities to a networking platform. This dual simulation environment has been tested for implementing agents in a DiffServ network to improve its performance. Simulation results show the efficiency of integrating agents within telecommunication networks and also prove that such a dual simulation environment is needed to test new techniques based on agents and multi-agent systems in networking