The current issue of the IETE Journal of Research (Vol.60, No.3, May–June 2014) contains seven articles. These articles present on-going research and developments taking place in the broad areas of Communication Engineering, Electromagnetics, and Electrical Engineering.
The paper “Generic constructions and transformation of decryption consistent encryption” is concerned with the problem of encryption and decryption in a broadcast situation such that a secret message is received by a group of users securely. The method is investigated in the framework of binding encryption wherein some transformations are given to provide greater security in terms of anonymity, strong decryption consistency and non-malleability.
The next paper, on “User authentication based on keystroke dynamics”, gives a method to verify user identity using keystroke dynamics from short text obtained during a computer login task. The verification is based on two features extracted from the typing sequence. The features are used for training a GMM and neural network classifier. The performance is studied using login strings collected from legal users and intruders.
The paper on “Optimum design of an envelope tracking buck converter for radio frequency power amplifier using GaN HEMTs” is in the area of radio link design to maximize data rates with given bandwidth and other resources. The paper considers the problem of optimization of radio frequency power amplifier performance for envelope tracking and envelope elimination and restoration purposes. A filter design methodology is given for new switching devices based on Gallium Nitride with the objectives of efficiency enhancement of signal transmission and bandwidth utilization. The performance is optimized with power loss models and experimental results are given.
In the paper “Bandwidth enhancement techniques for printed rectangular monopole antenna” the authors present the study of printed rectangular monopole antennas with single, dual and triple microstrip line feed and offset feed. The effect of feed networks to enhance the impedance bandwidth is studied in detail in this paper. The effects of patch width variation on bandwidth have also been reported and both simulated and experimental results are presented.
The paper entitled “Novel technique of optimizing FOPID Controller parameters using BBBC for higher order system” presents a computer-aided technique to optimize the fractional-order proportional integral derivative (FOPID) controller parameters including the integral order and derivative order. The authors have used heuristic population based Big Bang Big Crunch (BBBC) optimization technique in the proposed scheme. Compared with the recently published work, the superiority of FOPID controller using BBBC has been demonstrated. The authors have also reported that the same algorithm can be applied for designing FOPID controllers in case of linear fractional-order continuous systems as well as linear discrete systems including both integer and fractional order.
In the paper entitled “New microstrip band pass filter designs based on stepped impedance Hilbert fractal resonators”, the authors have proposed novel microstrip band pass filters based on stepped impedance resonator (SIR) principle on each strip of Hilbert fractal geometry. The proposed filters are composed of dual microstrip resonators based on first and second iteration Hilbert fractal curves. The proposed filter designs offer small sizes and low insertion loss and offers tuning feature to control the transmission zeros to certain extent through the variation of the feed line tap positions. The filters have been developed at centre frequency of 2.4 GHz using a substrate having dielectric constant of 9.6 and thickness 0.508 mm. Simulation responses show that these filters possess good frequency response characteristics with second harmonics suppression.
In the next paper, “Novel approach to sub-graph selection over coded wireless networks with QoS constraints”, the authors have studied the problem of minimum-cost multicast with network coding, keeping the maximum end-to-end weight, such as delay, throughput, and security, along paths from the source to each destination bounded by a constant. A path-based mixed integer programming model for the problem has been used and it has been shown that the problem is non-deterministic polynomial (NP)-hard. A minimum-cost multicast with end-to-end QoS over coded packet networks is used. It has been shown that the optimal costs in the minimum-cost QoSCP problem are greater than the optimal costs in the MCMCP problem.
Related Research Data
