recently a new structure called groove gap waveguide (GGW) i s introduced to implement low loss microwave component devices especi ally for millimeter wave applications. This paper presents a new type of H-plane horn antenna making use of this new technology in which Back ward radiation is significantly suppressed by introducing a high impeda nce surface at the antenna aperture. The high impedance surface that w e used as the Back lobe suppressor is a corrugated surface. The designed antenna is simulated by HFSS and its radiation performance is compar ed with an ordinary GGW H-plane horn in which no Back lobe Suppression mechanism is used. Results show a significant improvement in Back lobe Suppression and gain enhancement by the proposed structure.

A 17-year-girl presented with recurrent pain in abdomen of 10-year duration. The pain used to start as dull ache on right side of her abdomen, which gradually would increase over few hours to become moderately severe. This was not associated with nausea, vomiting, abdominal distension, respiratory, bowel or urinary symptoms, jaundice or fever. The pain usually lasted for 4-6 hours and subside on its own mostly or at times with oral analgesics. Such episodes became more frequent with increasing severity of pain from last 2 years. She visited many local practitioners for same to no avail. On careful evaluation, she revealed history of significant blunt trauma to abdomen at the age of 5 years due to fall from a swing.

The nonlinear behavior analysis and chaos control for Duffing-Holmes chaotic system is discussed in this paper. In order to suppress the irregular chaotic motion, an optimal Back-stepping controller is designed. The Back-stepping method consists of parameters with positive values. The improper selection of the parameters leads to inappropriate responses or even may lead to instability of the system. In this paper, the Unified particle swarm optimization (UPSO) algorithm is utilized to determine the convenient and optimal values of the parameters. The minimized objective function via UPSO algorithm is a weighted sum of the Integral of Time multiplied Absolute Error (ITAE) and squared control signal. Fast control of chaos in a very short time and having more limited control signal for this purpose, are the great advantages of the proposed controller. Numerical simulations show the high performance of this method for chaos elimination in Duffing-Holmes system.