Derivations and Centroids of Four Dimensional Associative Algebras

In this paper, we focus on derivations and centroids of four dimensional associative algebras. Using an existing classification result of low dimensional associative algebras, we describe the derivations and centroids of four dimensional associative algebras. We also identify algebra(s) that belong to the characteristically nilpotent class among the algebras of four dimensional associative algebras.Comment: 20 pages, 2 tables, Accepted in International Journal of Pure and Applied Mathematic

Design of Frequency Reconfigurable Multiband Compact Antenna using two PIN diodes for WLAN/WiMAX Applications

YesIn this paper, we present a simple reconfigurable multiband antenna with two PIN diode switches for WiMAX/WLAN applications. The antenna permits reconfigurable switching in up to ten frequency bands between 2.2 GHz and 6 GHz, with relative impedance bandwidths of around 2.5% and 8%. The proposed antenna has been simulated using CST microwave studio software and fabricated on an FR-4 substrate. It is compact, with an area of 50 × 45 mm2, and has a slotted ground substrate. Both measured and simulated return loss characteristics of the optimized antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications. Moreover, there is good agreement between the measured and simulated result in terms of radiation pattern and gain.Engineering and Physical Science Research Council through Grant EP/E022936A

The Design of a Uniplanar Printed Triple Band-Rejected UWB Antenna using Particle Swarm Optimization and the Firefly Algorithm

YesA compact planar monopole antenna is proposed for ultra-wideband applications. The antenna has a microstrip line feed and band-rejected characteristics and consists of a ring patch and partial ground plane with a defective ground structure of rectangular shape. An annular strip is etched above the radiating element and two slots, one C-shaped and one arc-shaped, are embedded in the radiating patch. The proposed antenna has been optimized using bio-inspired algorithms, namely Particle Swarm Optimization and the Firefly Algorithm, based on a new software algorithm (Antenna Optimizer). Multi-objective optimization achieves rejection bands at 3.3 to 3.7 GHz for WiMAX, 5.15 to 5.825 GHz for the 802.11a WLAN system or HIPERLAN/2, and 7.25 to 7.745 GHz for C-band satellite communication systems. Validated results show wideband performance from 2.7 to 10.6 GHz with S11 ˂ -10 dB. The antenna has compact dimensions of 28 × 30 mm2. The radiation pattern is comparatively stable across the operating band with a relatively stable gain except in the notched bands.This work was supported in part by the United Kingdom Engineering and Physical Science Research Council (EPSRC) under Grant EP/E022936A, TSB UK under grant application KTP008734 and the Iraqi Ministry of Higher Education and Scientific Research