35 GHz dielectric resonator stabilised gunn oscillator

A 35 GHz dielectric resonator oscillator(DRO) using GaAs Gunn diode in microstrip configuration has been designed and developed. The oscillator, with an integral waveguide-to-microstrip transition, delivered an output greater than 18 dBm. Phase noise of the oscillator is found to be better than ?80 dBc/Hz at 100 KHz away from the carrier. A frequency drift of about ±25 MHz has been observed over the temperature range from ?10 °C to 50 °C.     

Function dependent fully testable programmable logic array

Two techniques for designing function-dependent easily testable programmable logic arrays are presented. The techniques can detect all the multiple stuck-at, crosspoint and bridging faults, as compared with most of the existing techniques where some of the faults, especially bridging faults, remain undetected.<>     

Spectrum efficiency analysis for microcellular mobile radio systems

Spectrum efficiency is analysed in a microcellular mobile radio environment considering an appropriate model for UHF ground-wave path loss. The influence of cluster size and reuse distance on the spectrum efficiency is investigated by obtaining the probability of cochannel interference for uncorrelated Rayleigh fading interferers and Rician fading desired signal. The effect of traffic intensity is also considered in evaluating the spectrum efficiency.<>     

Synergistic interaction of 2-amino 4-methyl benzothiazole (AMBT) and benzotriazole (BTZ) offers excellent protection to mild steel exposed in acid atmosphere at elevated temperatures: Electrochemical,computational and surface studies

The synergistic interactions and corrosion protection properties of 2-amino 4-methyl benzothiazole, (AMBT) and 1, 2, 3-benzotriazole (BTZ) have been studied for mild steel in HCl at elevated temperatures. The extent of synergistic interaction increases with temperature. The methods of study include the conventional weight loss studies, computational screening, surface characterization and electrochemical studies. Quantum chemical approach was used to calculate some electronic properties of the molecules and to ascertain the synergistic interaction, inhibitive effect and molecular structures. The corrosion inhibition efficiencies and the global chemical reactivity relate to parameters like total energy, E_HOMO, E_LUMO and gap energy (ΔE). Condensed atom Fukui functions also calculated using DFT at B3LYP/6-31G* level, and were found to be correlating with the experimental results.     

Experimental study of embedded insulated antennas

Experimental studies are reported of several coaxial structures useful us embedded antennas and transmission lines. These include the insulated coaxial line with extended inner conductor, the insulated dipole with choke section, and the insulated sleeve dipole. The purpose of the experiments is to confirm theoretical calculations that involve numerous approximations.     

Reliable and Secure Cooperative Communication for Wireless Sensor Networks Making Use of Cooperative Jamming with Physical Layer Security

Interference is generally considered as the redundant and unwanted occurrence in wireless communication. This research work proposes a novel cooperative jamming mechanism for scalable networks like wireless sensor networks which makes use of friendly interference to confuse the eavesdropper and increase its uncertainty about the source message. The communication link is built with the help of Information theoretic source and channel coding mechanisms. The whole idea is to make use of normally inactive relay nodes in the selective Decode and Forward cooperative communication and let them work as cooperative jamming sources to increase the equivocation of the eavesdropper. In this work, eavesdropper’s equivocation is compared with the main channel in terms of mutual information and secrecy capacity.     

Triple Band Annular Ring Loaded Stacked Circular Patch Microstrip Antenna

In this paper a novel structure of annular ring loaded stacked circular patch microstrip antenna is theoretically analysed to observe various parameters such as return loss, input impedance, gain, directivity and radiation pattern. It is found that antenna possess three band of operation which signify the compactness and multiband operation of antenna. The antenna is resonating at three operating frequencies 1.720, 2.950, 3.060 GHz. The proposed theory is verified by simulation using Ansoft’s HFSS and theoretical results are in good agreement with simulated results. The antenna is useful for multi-services operations such as WLAN, GSM, UMTS, and WiMAX services.     

A hybrid fuzzy neural network-expert system for a short term unit commitment problem

The major aim of this paper is to develop a hybrid model to determine the unit commitment schedule of generating units. It is proposed to produce the unit commitment schedules in two steps. In the first step, the input layer of the neural network is designed to adopt nonlinear fuzzy membership values of the load demand profile. In the second step, an adaptive expert system is used to manipulate the schedules by using rule-base and inference mechanism. To demonstrate the effectiveness of this model, extensive studies have been performed for different load profiles belonging to the power systems of Tamilnadu consisting of thermal, nuclear, hydro, wind and diesel power plants.     

Mobility Impact on Cluster Based MAC Layer Protocols in Wireless Sensor Networks

Wireless sensor networks (WSNs) enable a wide variety of applications resulting in still increasing requirements for the protocols supporting the operations. The medium access control (MAC) layer protocols are essential for improving the performance of an application and its quality of service because MAC protocols influence channel capacity utilization, network delay, energy consumption, and scalability. The contribution of this paper is two novel cluster-based time division multiple access (TDMA) scheduling MACs for WSNs and an analysis of the mobility impact on both. The proposed MAC layer protocols support real time applications where the cluster-based scheduling improves the scalability and also improves the performance in varying network conditions. The paper presents the design, implementation and performance evaluation of the proposed cluster based TDMA scheduling algorithms green conflict free (GCF) and multicolor-GCF (M-GCF) for high complexity and high requirement applications of WSNs under both low and high mobility conditions. The comparative evaluation shows that the M-GCF algorithm has better slot sharing and less conflicts with reduced communication energy consumption, delay, and good throughput under static and low mobility conditions while the GCF algorithm has better performance in high mobility scenarios. The paper also defines the mobility threshold that decides the use of the GCF- and M-GCF algorithms according to the mobility requirement of application.