Scanning the Issue

The current issue of the IETE Journal of Research (Vol.64, No.5, Sep.-Oct. 2018) contains 14 articles. These articles present the ongoing research and developments taking place in the broad areas of Power Systems, Signal Processing, Microwave Engineering, Computer Science and Engineering, Control Systems and Wireless Communication.

The paper on “A new sliding-mode approach to control the active and reactive powers with variable switching frequency for grid-connected converter,” presents a method for direct power control of the instantaneous active and reactive powers for three-phase grid-connected converters. It combines direct power control with sliding mode control and variable switching based on look-up table. This method eliminates the requirement of a rotating coordinate transformation and angular information of the grid voltage. The method has been realized on an experimental test bench and the power quality has been evaluated under steady-state and transient operations. The inferences drawn from the study are presented.

The next paper on “An accurate and simple approach to detect eye centers in low resolution face images,” presents an algorithm for accurate detection of the center of the eye in low resolution face images. The utility of the algorithm is in the design of real-time eye gaze tracking applications. It uses the image gradients algorithm for detection. An attractive aspect of the algorithm is its simple approach while giving accuracies that are comparable to algorithms that have much higher computational complexity and training requirements.

In “An enhanced gain dual-polarized dielectric resonator antenna array with high isolation for C-band applications,” the design of a high gain dual-polarized two-element cylindrical dielectric resonator antenna array is presented for the 6.0-6.6 GHz band. The advantages of the given design are highlighted. The gain, radiation efficiency performance, radiation pattern, isolation of antenna, and other parameters of performance are given for the design and experimental realization.

The paper on “Comparison of cost, power consumption, and spectrum utilization in protected fixed-and flexi-grid optical networks,” presents a simulation study of flexible elastic optical networks (EON) for network resilience under different parametric conditions and topologies. The EON has the property of squeezed protection that is useful. The EON is compared with wavelength-switched optical network (WSON) in terms of cost, power consumption and spectrum utilization, and inferences are made from this comparison study about the suitability of EON.

The following paper on “Comparison of reduced part count multilevel inverters (RPC-MLIs) for grid interfacing,” looks at specific topologies for the application of RPC-MLIs. A relevant perspective is provided on RPC-MLIs in view of their usefulness due to the good properties. The paper provides the analyses and comparisons in terms of number of switches, driver circuits, switching losses and other parameters, from which observations are made. A specific topology is proposed for high and medium voltage applications and for transformer-less and filter-less direct grid integration systems.

In “Detection and characterization of bearing faults from the frequency domain features of vibration,” the authors study the suitability of frequency domain features to monitor the vibrations in running machinery leading to the detection and analysis of bearing faults in machinery. A vibration monitoring method for the detection of bearing faults is attractive due to the non-intrusive nature of the method. A statistical analysis of the frequency domain features is presented to quantify their significance in the detection of bearing faults.

In the next paper titled “Genetic-algorithm based energy-efficient clustering (GAEEC) for homogeneous wireless sensor networks,” an algorithm is presented for improving the stability duration and overall lifetime of a wireless sensor network. This is a requirement due to the battery-operated sensors. The energy consumption varies in inter-cluster and intra-cluster communications due to several factors, leading to heterogeneous energy consumption patterns, that eventually leads to reduced network lifetime. The paper studies the proposed protocol using simulations and compares it with a state-of-the-art algorithm.

The paper titled “Reduction of peak-to-average power ratio of OFDM system using triangular distribution based modified companding scheme,” gives a non-linear companding transform technique to reduce the peak-to-average power (PAPR) ratio of OFDM systems. It is well-known that OFDM modulation technique has large PAPR of the transmitted signal that results in performance degradation. The proposed technique is also studied for PAPR reduction performance for other digital modulation techniques. Analytical and simulation studies have been presented to compare the PAPR reduction, BER performance and bandwidth efficiency of these modulation techniques, from which inferences are made in the paper.

The next paper on “Refinement of HMM model parameters for Punjabi automatic speech recognition (PASR) system,” addresses the problem of Hidden Markov model (HMM) training for speech recognition. It presents two classifier systems using HMM, ie. Genetic algorithm based HMM (GA-HMM) and Differential evolution based HMM (DE-HMM) that modifies the feature vectors that contribute to reduction in training complexity from large databases. The method is compared with classical HMM on benchmark database to assess performance improvement in pattern matching tests on Punjabi speech.

In “Robust estimator design for control of electropneumatic system,” the authors present an estimation method for speed and acceleration signals corresponding to higher order sliding mode time derivatives, in the control loop of a dynamic system. The optimal control of electropneumatic systems generally requires the feedback of these two signals. The proposed method compromises between the requirements of precision and noise robustness. The paper presents simulation and experimental analysis, and demonstrates its effectiveness in the control of a electropneumatic system.

The next paper “Second-order measures of performance of dual SC macro-diversity system with unbalanced BSs exposed to CCI in composite fading channels,” studies the dynamic characteristics of micro- and macro-diversity of wireless channels in the presence of co-channel interference (CCI). The relevance of unbalanced base-station scenario is discussed. The paper presents the infinite-series expressions for second-order performance measures for base-stations. Closed-form expressions are presented for the second order performance measures for Rayleigh distribution assumptions for the co-channel interference and under conditions of unbalanced base-stations. The infinite-series expressions exhibit rapid convergence that is useful in real-time implementation cases.

The next paper on “Security enrichment with trust multipath routing and key management approach in WMN,” addresses the problem of security vulnerabilities in wireless mesh networks by presenting securing routing protocols for the transmission of video frames. A trust management scheme comprising of two components viz. direct trust and indirect trust, is integrated that enhances the security in path selection. The trust management scheme in the protocol is studied in simulation environment and compared with other trust management schemes in terms of several parameters, and inferences are drawn from it.

In the paper “Spatio-temporal network-constrained trajectory data model and service reliability assessment,” the spatio-temporal data of vehicles’ movement obtained from GPS survey is analyzed to improve the efficiency of transport service. Based on the study of real data, suitable inferences are drawn.

Finally, in the paper on “Time-domain solution for corner diffraction of UWB signals by flat plate structures with the higher order diffraction included,” presents a time-domain solution for the corner diffraction from finite-edge flat plate structures of ultra-wideband signals. The diffraction by edges of a horn antenna is presented. The paper compares the time-domain solution with frequency-domain solution techniques to establish the efficacy of the presented solution.

Additional information

Notes on contributors

Shiban K. Koul

Shiban K Koul is Dr. R.P.Shenoy Astra Microwave Chair Professor at the Indian Institute of Technology, Delhi. He served as Deputy Director (Strategy and Planning) at IIT Delhi from 2012-2016. Currently, he is the Mentor Deputy Director (Strategy & Planning, International affairs and R&D) at IIT Jammu. He is also the Chairman of Astra Microwave Products Limited, Hyderabad. His research interests include: RF MEMS, High Frequency Wireless Communication, Microwave Engineering, Microwave Passive and Active Circuits, Device modeling, Millimeter wave IC design and Reconfigurable microwave circuits including antennas. Completed 34 major sponsored projects, 52 consultancy projects and 56 Technology Development Projects. Authored 375 Papers, 8 state-of-the art books and 3 book Chapters. He holds 10 patents and 6 copyrights. He is a Fellow of IEEE, INAE and IETE. He is the Chief Editor of IETE Journal of Research, Associate Editor of the International Journal of Microwave and Wireless Technologies, Cambridge University Press. He served as a Distinguished Microwave Lecturer of IEEE MTT-S for the period 2012-2014.

Recipient of numerous awards including IEEE MTT Society Distinguished Educator Award (2014); Teaching Excellence Award (2012) from IIT Delhi; Award for contributions made to the growth of smart material technology (2012) by the ISSS, Bangalore, Vasvik Award (2012) for the contributions made to the area of Information, Communication Technology (ICT) and M N Saha Memorial Award (2013) from IETE.

E-mail: [email protected]