Scanning the Issue

The second part of the current issue of IETE Journal of Research Vol 67 No 5, September - October 2021, includes 7 articles. These articles present ongoing research and developments taking place in the broad areas of computer science, microwave engineering, signal processing, biomedical engineering and electrical engineering.

The paper “Design and Low-Cost Implementation of an Electric Wheelchair Control” presents design and low-cost implementation of direction and speed controller for an electric wheelchair actuated using a permanent magnet direct current (PMDC) motor. Three different controllers are used to simulate the control of PMDC motor and parameters for real-time implementation of electric wheelchair control using PMDC motor are tuned. The authors have studied performance capability of the intelligent neural network and fuzzy logic controller and compared with proportional-integral-derivative (PID) controller with variations in speed. The PID, neural network and fuzzy logic controller are designed using Matlab-Simulink for PMDC motor and the controller parameters are tuned for driving the wheelchair in the real-time implementation using the ATmega 328P microcontroller.

In the next paper “Facial Expression Recognition Using Graph Signal Processing on HOG”, the authors have observed that the Histogram of Oriented Gradient (HOG) is an effective method for the face detection as well as the facial expression recognition. However, due to the large feature length of the facial expression, there is a challenge to decrease the size of the feature vector. The authors have presented a novel method using the graph signal processing (GSP) with the HOG to reduce the length of the feature vector and to increase the accuracy for recognizing the facial expression. The proposed method is demonstrated on CK+and JAFFE database and the experimental performance is compared with the results of other methods using the same databases.

The paper on “Discrimination of Complex Radar Targets Using the Dominant Poles Determined in the Time and Frequency Domains” compares two techniques of discriminating complex objects, using the electromagnetic scattering response in the time and frequency domains. The scattering in the time and frequency domains are computed using the Finite Difference Time Domain (FDTD) method and the Method of Moments (MoM), respectively. The dominant Natural Resonant Frequencies (NRFs) of the objects are identified, using the Matrix Pencil of Function (MPoF) algorithm from the scattering response in the time domain, and the Vector Fitting (VF) method using the response in the frequency domain. The dominant NRFs in both cases have been identified after thresholding the power contribution of each pole. A “Risk” function using the dominant poles of any two scattering objects is then defined, which aids in quantifying the discrimination. Perfectly Electrically Conducting (PEC) objects with minor variations in their geometric shape have been discriminated using the risk function. Authors have shown that both approaches, using the time and frequency domain scattering response are found to yield identical results. It has been demonstrated that a single run of the FDTD algorithm is sufficient to compute the electromagnetic response required to determine the dominant natural resonances.

The paper titled “Full-bridge LLC Resonant High-voltage DC–DC Converter with Hybrid Symmetrical Voltage Multiplier,” presents an LLC resonant high-voltage DC–DC converter based on the hybrid symmetrical voltage multiplier that consists of the full-bridge inverter circuit, one resonant tank circuit, one power transformer, and the voltage multiplier circuit. It has been reported that the proposed converter operates below resonance on the negative slope region of DC characteristics curve for realization of zero voltage switching (ZVS) operation. Within this operating region, the power switches and output diodes of the converters generally operate under the ZVS and zero current switching (ZCS) conditions, respectively. Detailed structure, design procedure, operation, and steady-state analysis of the proposed converter are described in detail in this paper. Using an experimental prototype, the proposed converter has been shown to operate under soft-switching conditions, resulting in higher efficiency. The maximum efficiency of the proposed converter of about 96% is reported at output power of 550 W.

In “Novel Technology for Lung Tumor Detection Using Nano image,” the authors proposed NBDS method-a nanotechnology based detection scheme to detect the lung tumors in nanoscale range. The shape and size of pulmonary nodules are used to diagnose lung cancer in CT images. Image processing algorithms are reported as an aid to detect and localize nodules. The input Nanoimage is enhanced by using the technique of unsharp masking with the anisotropic filter. By using toboggan algorithm, lung cancer images are segmented. Nano measuring tool for graphical user interface is developed in MATLAB software to detect the lung tumor area or lung lesion in the body (in nanometers). Image classification and feature extraction are done by K-nearest neighbor (KNN) and support vector machine (SVM) with Bag of Visual Words (BoVW) classifiers. The overall accuracy of 97% is obtained using GLCM and FOS features in MATLAB software. It has been shown that the convolutional neural network (CNN) classifier gives the maximum accuracy of 98.19% in MATLAB 2017a software, and hence, this classifier does not need the feature extraction step. Using the proposed method, the average time consumption for one lesion segmentation is under 4sec using the method proposed by the authors.

The next paper titled “Analysis of Photonic Crystal Diffraction Grating Based Light Trapping Structure for GaAs Solar Cell,” presents design and quantitative analysis for an efficient light-trapping structure (LTS) based on Photonic Crystals (PhC) to enhance the performance of thin-film GaAs solar cells. LTS consists of single planar Anti-Reflection coating (ARC) layer at the top assisted by 2D PhC diffraction grating and Distributed Bragg Reflector (DBR) having alternate dielectric layers at the back of the active layer. The structure has been optically analyzed for various absorption layer thicknesses and compared with Lambertian limits, and it has been shown that with the optimization of the design carefully, significant enhancement in the cell efficiency takes place for the presented LTS, especially for the devices with very thin absorption layers (typically less than 1000 nm). Further, it is demonstrated that this efficiency enhancement is attributed to the improvement in photon absorption in the wavelength range for which active layer thickness itself is not sufficient for absorption. According to the simulation analysis, the proposed cell efficiency can be enhanced 3.5 times for a 100nm cell with LTS, and this enhancement shrinks only to 1.5 times for 1500nm cell. The paper also presents the quantitative and comparative analysis of the proposed design with different compatible designs such as a cell having double layer ARC and a cell having pyramidal ARC with PhC as BR design.

The paper on “Gain and Bandwidth Enhancement of Microstrip Patch Antenna for WiMAX and WLAN Applications” presents a high-gain broadband microstrip patch antenna using a PTFE substrate of dielectric constant 2.4 with a modified radiating patch. Two different shapes of ground planes (rectangular and circular) are used under the proposed radiating patch to enhance the antenna gain. The lateral dimensions of the proposed patch are 0.52λ₀×0.51λ₀, where λ₀ is the free space wavelength at f₀ = 5.65 GHz. Total of five slits and a slot are embedded at the optimum position on the proposed patch. The effects of each slit on bandwidth and gain are demonstrated. The covered frequency band is around 2 GHz (5.5–7.5 GHz). The achieved peak gains are 7 dBi at 5.65 GHz and 9 dBi at 7.5 GHz and the percentage bandwidth is 30.77.

Additional information

Notes on contributors

Shiban K Koul

Shiban K Koul is currently an Emeritus Professor at the Indian Institute of Technology, Delhi. He served as Deputy Director (Strategy and Planning) at IIT Delhi from 2012-2016. He is currently Mentor Deputy Director (Strategy & Planning, Research) at IIT Jammu from 2018-onwards. He also served as the Chairman of Astra Microwave Products Limited, Hyderabad from 2009-2019 and Dr R P Shenoy Astra Microwave Chair Professor at IIT Delhi from 2014-2019. His research interests include RF MEMS, high frequency wireless communication, microwave engineering, microwave passive and active circuits, device modelling, millimetre and sub-millimetre wave IC design, body area networks, flexible and wearable electronics and reconfigurable microwave circuits including miniaturized antennas. Successfully completed 38 major sponsored projects, 52 consultancy projects and 61 technology development projects. He has authored/co-authored 517 research papers, 15 state-of-the art books, 4 book chapters and 2 e-books. He holds 22 patents, 6 copyrights and one trademark. He has guided 26 PhD theses and more than 120 master’s thesis. He is a Life Fellow of IEEE and Fellow of 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; Indian National Science Academy (INSA) Young Scientist Award (1986); Top Invention Award (1991) of the National Research Development Council for his contributions to the indigenous development of ferrite phase shifter technology; VASVIK Award (1994) for the development of Ka- band components and phase shifters; Ram Lal Wadhwa Gold Medal (1995) from the Institution of Electronics and Communication Engineers (IETE); Academic Excellence Award (1998) from Indian Government for his pioneering contributions to phase control modules for Rajendra Radar, Shri Om Prakash Bhasin Award (2009) in the field of Electronics and Information Technology, VASVIK Award (2012) for the contributions made to the area of Information, Communication Technology (ICT) and M N Saha Memorial Award (2013) from IETE. Email: [email protected]