Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

This Chapter presents behavioral analysis of ohmic contact micromachined switches. In this Chapter, electrostatically actuated micromachined switch configurations that can be easily integrated in uniplanar circuits are presented. The design procedure and fabrication process of micromachined switch topologies that can control the propagating modes of multimodal uniplanar structures (based on a coplanar waveguide (CPW)) are be described in detail. Generalized electrical (multimodal) and mechanical models will be presented and applied to the switch design and simulation. The switch-simulated results are compared to measurements, confirming the expected performances. Mostly cantilever types of switches are chosen in this study and analysis procedure is described with lumped model representation. Different types of ohmic-contact switches are discussed in this Chapter with extensive set of measurement stages. It includes switch profile analysis where surface profile and initial deformation are measured using Optical Profilometer, mechanical resonance frequency measurement and characterization using Laser Doppler Vibrometer (LDV), characterization of switch actuation and release voltages using LCR meter under a DC probe station, switching and release time measurements utilizing a proposed set up, linearity and temperature stability analysis and characterizations within a laboratory environments, S-parameter measurements using RF probe station with a Vector Network Analyzer (VNA) followed by the power handling capability and its analysis within a laboratory environments. Switch performances are discussed against each measurement stages. Functionalities of ohmic contact broadband switches are discussed with behavioral analysis. Comparison between simulated versus all measured responses are discussed up to a reasonable extent. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

World University root node

Department of Electrical Engineering

Micromachined Circuits and Devices

Micromachined Single-Pole-Single Throw Switches

This work presents a broadband linear-cross polarizer for K and Ka-band applications. The design consists of a simple asymmetric widths based meander-line metasurface printed on a thin FR-4 grounded-dielectric substrate. Normal incidence demonstrates 90% Polarization Conversion Ratio (PCR) Bandwidth (BW) of 20.64 GHz from 18.31 to 38.95 GHz with 72.1% Fractional Bandwidth (FBW). Due to the destructive interference involved at greater oblique angles, reflective polarizers experience severe degradation of 90% PCR BW response. The proposed polarizer is obliquely stable up to 43° for Transverse Electric (TE), 45° for Transverse Magnetic (TM) incidence with a lesser 90% PCR BW reduction of only 13.95% (TE) and 15.25% (TM) compared to normal incidence.

IEEE Transactions on Antennas and Propagation

Broadband Chiral-type Linear to Linear Reflecting Polarizer With Minimal Bandwidth Reduction at Higher Oblique Angles for Satellite Applications

An Ultra-Wideband (UWB) Antipodal Vivaldi Antenna (AVA) is introduced here for microwave imaging applications. The AVA accomplishes high transmission capacity from 1.2-14 GHz with a maximum gain of 13 dBi at 10 GHz. The antenna is utilized for the identification of a metal object located inside a human stomach cross-section modelled in the simulator. A suitable imaging algorithm is devised to identify the material inside the stomach. The algorithm can locate the exact coordinates of the metallic objects along with their actual dimensions used in the simulations. Further, the resolution of the image has been improved. © 2022 IEEE.

2022 IEEE Wireless Antenna and Microwave Symposium, WAMS 2022

Metallic Object Detection Inside Human Stomach With Antipodal Vivaldi Antenna Utilizing Microwave Imaging Technique

This Chapter presents different types of micromachined antennas at mm-wave frequencies. The design and fabrication of a Ka-band inset-fed microstrip patch antenna on a suspended 2 µm thick silicon-dioxide membrane using silicon bulk-micromachining technique have been discussed. The complete antenna structure is realized using post - CMOS and post-MMIC compatible metal dielectric deposition techniques. The parametric study to obtain the optimized inset length is also presented. Three different patch antennas integrated with micromachined SPDT and SP9T switches are presented at 60 GHz for different wireless applications at ISM band of 60 GHz. The utilization of SPDT switch in front end transmit/receive module is discussed with experimental investigation. The SP9T based antenna is a preliminary prototype for the proof of concept of antenna sectoring at 60 GHz for ISM applications. A 77 GHz micromachined polarization reconfigurable antenna is discussed, and it has capability to generate all polarization states. This antenna illustrates a measured return loss of &gt;20 dB, −10 dB bandwidth of 10% and 14.3% in LP and CP cases respectively, at 77 GHz. A minimum best value of 1.1 dB axial ratio is accomplished at 77 GHz in circularly polarized state from this antenna. Next design and development of active micromachined antenna is presented. Finally, this Chapter concludes with design guideline for designing and developing micromachined cavity antenna including antenna arrays. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Micromachined Antennas

This paper investigates the potential impact of inverter based resources (IBRs) on the well known negative sequence impedance (NSI) element (32Q) based directional relaying scheme. CIGRE-14 bus test system with IBRs is modeled on PSCAD environment. Both the inverter control along with the directional relay scheme are modeled in detail. The test results indicate that the conventional 32Q element will find its limitations in the presence of IBRs. Absence of significant level of negative sequence fault current along with changed angular relationship between negative sequence voltage and current are found out to be the primary causes behind such relay mal-operations. Further, the impact of connections of interconnecting transformer are also analyzed. © 2022 IEEE.

2022 22nd National Power Systems Conference, NPSC 2022

Revisiting Performance of Negative Sequence Directional Relay (32Q) in the Presence of Inverter Based Resources

Perovskite-silicon tandem solar cells show enhanced efficiencies due to the broader absorption of the solar spectrum. Luminescent coupling is generally observed in multi-junction solar cells, where a fraction of emitted photons from the higher bandgap optically active layer are absorbed by the lower bandgap optically active layer and converted to photocurrent. Therefore, it is necessary to model the current-voltage characteristics of perovskite-silicon tandem solar cells to understand the impact of luminescent coupling on the performance of these devices. In our work, we have a semi-analytical framework to obtain the current-voltage characteristics of multijunction perovskite-silicon tandem solar cell, accounting for the presence and absence of luminescent coupling. We have compared the calculated current-voltage characteristics with experimentally measured data reported in literature. © 2022 IEEE.

Proceedings of the IEEE Conference on Nanotechnology

Analysis of perovskite-silicon tandem solar cells using a semi-analytical model

While there have been extensive reports in literature regarding the synthesis of porous silicon layers using electrochemical anodization for their use in different applications, systematic studies regarding the influence of the substrate dopant concentration and the electrolyte composition on the pore dimensions have not not been extensively investigated. In this work, we have systematically looked at the influence of dopant concentration and different electrolyte compositions on the pore dimensions of the porous silicon layer, along with varying input current density and reaction time. © 2022 IEEE.

2022 IEEE Nanotechnology Materials and Devices Conference, NMDC 2022

Modulation of Porous Silicon Morphology: Correlation with Dopant Concentration and Electrolyte Composition

The vital signs can vary significantly depending on the daily physical activities, which may not be due to defects of the organs. Under remote human health-monitoring applications, for reliable disease diagnosis, recorded biomedical signals such as an electrocardiogram (ECG) and a photoplethysmogram (PPG) must be indexed with physical activity information, as it is unknown to the physicians and also to the computer-aided diagnostic system. Since deep-learning (DL) networks were explored for various vital signs extraction and disease classification, we present an effective convolutional neural network (CNN)-based human activity recognition (HAR) method by exploring suitable hyperparameters. CNN-based methods are evaluated using the acceleration signals taken from the standard HAR benchmark database, University of California, Irvine (UCI) with accuracy (ACC), model size (in kB), and processing time (PT), and also implemented on the Raspberry Pi 4 (R-Pi-4) to study real-time feasibility. Evaluation results showed that higher HAR accuracy can be achieved with the activation function of the exponential linear unit (ELU) for the 2-layer CNN with a segment size of 2.5 s (ACC of 89.05% and PT of 0.142 ms), the 4-layer CNN with a segment size of 1 s (ACC of 91.66% and PT of 0.541 ms), and the 6-layer CNN with a segment size of 2 s (ACC of 91.18% and PT of 1.672 ms). Results demonstrated that the selection of an optimal number of layers and hyperparameters plays a major role in achieving higher accuracy with lower computational time on both personal computer central processing unit (PC-CPU) and R-Pi computing platforms, which were not addressed in past studies. © 2001-2012 IEEE.

IEEE Sensors Journal

Convolutional Neural Network-Based Human Activity Recognition for Edge Fitness and Context-Aware Health Monitoring Devices

The soft-switched modulation techniques presented in recent literature for single-phase half-bridge matrix-based dual-active-bridge (MB-DAB) ac-dc converter either suffers from incomplete soft-switching or computationally and memory expensive numerical technique requirement. An analytical expression-based modulation scheme for half-bridge MB-DAB, which is directly implementable on a microprocessor, is presented in this article that is capable of achieving near full-cycle ZVS turn-on of all MOSFETs and unity power-factor (UPF) operation. The theoretical derivations, working principles, and loss modeling are presented through suitable formulations. A 2.2-kW(pk) hardware prototype is fabricated, for which a PSIM simulation model is also developed using the MOSFET manufacturer's SPICE models and other components' datasheet parameters. The experimental results demonstrate near full-cycle ZVS turn-on over a wide load range (12\%-100\%), UPF operation, and 96.6\% conversion efficiency at full-load in agreement with the simulation results, which validate the proposed modulation approach.

IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS

Analytical Expression-Based Modulation for Soft-Switched Matrix-Based Dual-Active-Bridge (S2MB-DAB) Single-Phase AC-DC Converter

In the context of an (n,k,m) convolutional code where k is the number of message symbols, n the number of code symbols and m the memory, Martinian [1] introduced the concept of information debt whose value at time t is the number of additional coded symbols needed to decode all prior message symbols. The same paper shows the existence of (n,k,m) convolutional codes that can recover all prior message symbols whenever the symbol-erasure pattern is such that the maximum time interval τ between successive returns to zero of the information debt function is at most m. The parameter τ also represents the worst-case delay in decoding a message symbol. In the present paper, we study (n,k,m) convolutional codes that possess the analogous property for the case τ > m whenever it is possible to do so. We will refer to such codes as information-debt-optimal streaming (iDOS) codes. We prove the existence of periodically time-varying iDOS codes for all possible {n,k,m,τ} parameters. We also show that m-MDS codes and Maximum Distance Profile convolutional codes are iDOS codes for certain parameter ranges. As a by-product of our existence result, the minimum memory needed for a particular class of streaming codes studied earlier in the literature, is determined. © 2022 IEEE.