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

In this study, a compact modified circular ring-based circuit analog absorber (CAA) is proposed. It comprises a resistor-loaded frequency selective surface (FSS) underneath an FR-4 substrate, and the other end is terminated with a perfect electric conductor (PEC) separated by an air-spacer. The proposed design shows a minimum -10 dB reflectance from 10.55 to 36.03 GHz (25.48 GHz bandwidth and 109.4% fractional bandwidth) with two dips at 13.5 GHz and 35.23 GHz having reflectivity -17.18 dB and -24.9 dB, respectively. The existing four-fold circular symmetry architecture shows insensitivity for different polarization angles under normal incidences and up to 45° stability for Transverse Electric (TE) and Transverse Magnetic (TM) modes under oblique incidences. The proposed cell is compact with a periodicity of 0.193λL, and a thickness of 0.09λL, where λL is the free-space wavelength corresponding to the lowest frequency of the absorption band. The novelty of the design lies in the topology of using an underneath FSS to take advantage of effective permittivity control for both broader bandwidth and better angular stability. To demonstrate the ability of the proposed design, a 28 GHz microstrip patch antenna prototype is fabricated, and its radar cross section (RCS) is measured after loading with the absorber. A 15.15 dBsm RCS reduction is observed in comparison with the PEC. The authors strongly believe that the proposed design has potential applications such as RCS reduction and radio-frequency energy harvesting. © 2022 The Author(s). Published by Cambridge University Press in association with the European Microwave Association.

World University root node

Department of Electrical Engineering

International Journal of Microwave and Wireless Technologies

A novel modified circular ring-based broadband polarization-insensitive angular stable circuit analog absorber (CAA) for RCS applications

Real-time photoplethysmogram (PPG) denoising and data compression has become most essential requirements for accurately measuring vital parameters and efficient data transmission but that may introduce different kinds of waveform distortions due to the lossy processing techniques. Subjective quality assessment tests are the most reliable way to assess the quality, but they are time expensive and also cannot be incorporated with quality-driven compression mechanism. Thus, finding a best objective distortion measure is highly demanded for automatically evaluating quality of reconstructed PPG signal that must be subjectively meaningful and simple. In this paper, we present four types of objective distortion measures and evaluate their performance in terms of quality prediction accuracy, Pearson correlation coefficient and computational time. The performance evaluation is performed on different kinds of PPG waveform distortions introduced by the predictive coding, compressed sampling, discrete cosine transform and discrete wavelet transform. On the normal and abnormal PPG signals taken from five standard databases, evaluation results showed that different subjective quality evaluation groups (5-point, 3-point and 2-point rating scale) had different best objective distortion measures in terms of prediction accuracy and Pearson correlation coefficient. Moreover, selection of a best objective distortion measure depends upon type of PPG features that need to be preserved in the reconstructed signal. © 2013 IEEE.

Fulltext

IEEE Access

Evaluation of Objective Distortion Measures for Automatic Quality Assessment of Processed PPG Signals for Real-Time Health Monitoring Devices

For the internet of medical things (IoMT) enabled long-term health monitoring and disease prediction applications, there is a demand for an automatic photoplethysmogram (PPG) signal quality assessment (SQA) for reducing false alarms and energy consumption. This paper presents a PPG-SQA method by using raw PPG signal and convolutional neural network (CNN) with optimal parameters. The main focus of this paper is to find an optimal number of filters (16, 32, 64) and number of layers (2 and 4 layers) with rectified linear unit (ReLU) activation function and to study robustness of trained CNN models by using unseen PPG datasets and different kinds of noise sources, which are not addressed in the past studies on the CNN-based PPG-SQA methods. Evaluation results showed that the 4 layer CNN-based method had the higher accuracy of 99.58% for noise-free PPG (NF-PPG) versus wrist-cup noisy PPG signal database (MA-DB01), 99.99% for NF versus random noises added PPG (RN-PPG) signals, and 75.80% for NF-PPG versus acceleration corrupted PPG signals (MA-DB02). For the unknown dataset, the 4-layer CNN model had the higher accuracy of 96.71% for NF-PPG versus MA-DB01 and 99.04% for NF versus RN-PPG, and the 2-layer CNN model had the higher accuracy of 76.16% for NF-PPG versus MA-DB02 PPG segments. Results demonstrate that the CNN-based PPG-SQA method with optimal parameters is not only improve the accuracy but can also reduce the computational load as compared with other existing methods. © 2022 IEEE.

Proceedings - 2022 International Conference on Artificial Intelligence of Things, ICAIoT 2022

CNN Based PPG Signal Quality Assessment Using Raw PPG Signal for Energy-Efficient PPG Analysis Devices in Internet of Medical Things

Automatic atrial fibrillation (AF) detection is essential for preventing stroke due to silent heart diseases. In this paper, we propose an automatic AF detection by using electrocardiogram (ECG) signals and convolutional neural network. The proposed method is tested by using the ECG signals from Physionet. On the benchmark performance metrics, the proposed method achieved an average accuracy of 98.26% for detecting AF events. The proposed method can achieve the AF event detection with a processing time of 0.77±0.037 ms with the selection of optimal hyperparameters. The method has great potential in detection of AF events in ECG signal. © 2022 IEEE.

2022 4th International Conference on Cognitive Computing and Information Processing, CCIP 2022

Convolutional Neural Network Based Atrial Fibrillation Detection from ECG Signal

Biological Sciences and Engineering

Cellular and Molecular Immunology

Restoration of established systemic inflammation and autoimmunity by Foxp3+ regulatory T cells

Programmed death-ligand 1 (PD-L1) plays a key role in maintaining immune tolerance and also in immune evasion of cancers and pathogens. Though the identity of stimuli that induce PD-L1 in various human innate cells and their function are relatively well studied, data on the basophils remain scarce. In this study, we have identified one of the factors, such as IFN-γ, that induces PD-L1 expression in human basophils. Interestingly, we found that basophil priming by IL-3 is indispensable for IFN-γ-induced PD-L1 expression in human basophils. However, priming by other cytokines including granulocyte-macrophage colony-stimulating factor (GM-CSF) and thymic stromal lymphopoietin (TSLP) was dispensable. Analyses of a published microarray data set on IL-3-treated basophils indicated that IL-3 enhances IFNGR2, one of the chains of the IFNGR heterodimer complex, and CD274, thus providing a mechanistic insight into the role of IL-3 priming in IFN-γ-induced PD-L1 expression in human basophils. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Cells

IFN-$\gamma$ Induces PD-L1 Expression in Primed Human Basophils

Basophils play a key role in the orientation of immune responses. Though the interaction of SARS-CoV-2 with various immune cells has been relatively well studied, the response of basophils to this pandemic virus is not characterized yet. In this study, we report that SARS-CoV-2 induces cytokine responses and in particular IL-13, in both resting and IL-3 primed basophils. The response was prominent under IL-3 primed condition. However, either SARS-CoV-2 or SARS-CoV-2-infected epithelial cells did not alter the expression of surface markers associated with the activation of basophils, such as CD69, CD13 and/or degranulation marker CD107a. We also validate that human basophils are not permissive to SARS-CoV-2 replication. Though increased expression of immune checkpoint molecule PD-L1 has been reported on the basophils from COVID-19 patients, we observed that SARS-CoV-2 does not induce PD-L1 on the basophils. Our data suggest that basophil cytokine responses to SARS-CoV-2 might help in reducing the inflammation and also to promote antibody responses to the virus.

Frontiers in Immunology

SARS-CoV-2 Induces Cytokine Responses in Human Basophils.

The toroidal inductors are known for their higher flux densities, higher inductances, low losses in the windings, and less acoustic noise. This paper proposes novel concentric toroidal inductor configurations namely concentric toroidal inductors (CTI) used as power inductors and concentric toroidal differential-mode chokes (CTDMC) employed for DM noise filtration. The presented concentric toroidal structures provide improved inductances by utilizing the window area of the toroidal core. Analytical and experimental verifications prove the increment of inductance in CTI and CTDMI when compared to the corresponding traditional inductor confiaurations. © 2022 IEEE.

1st IEEE Industrial Electronics Society Annual On-Line Conference, ONCON 2022

New Toroidal Inductor Configurations for Improved Inductance

Global maximum power point tracking (GMPPT) algorithms are employed to extract the maximum available power from the photovoltaic (PV) arrays during partial shading conditions. However, the available GMPPT algorithms in the literature have disadvantages such as low convergence rate and requirement to scan for the local peaks. To overcome these drawbacks, this paper presents a fast and simple hybrid GMPPT algorithm, which combines the advantages of the binary search and the secant algorithms. The binary search algorithm is used for the global maximum power point (GMPP) reference generation and the secant algorithm is applied for tracking the generated power reference. The superlinear convergence rate of the secant algorithm and the logarithmic convergence rate of the binary search algorithm aid in fast convergence to the GMPP. The performance of the proposed hybrid GMPPT algorithm is validated through simulations in MATLAB-Simulink and also compared with a conventional GMPPT algorithm. © 2022 IEEE.

2022 IEEE Energy Conversion Congress and Exposition, ECCE 2022

Global Maximum Power Point Tracking for Photovoltaic Systems Using Hybrid Secant and Binary Search Algorithms

Power routing imbalance through the sub modules of a cascaded isolated medium-voltage AC - low-voltage DC (MVAC-LVDC) converter is inevitable due to the unavoidable drift/mismatch in values of passive components. In this paper, a comparative overview of the power imbalance issue and its mitigating control technique along with pertinent analysis is discussed for two-stage and single-stage isolated MVAC-LVDC cascaded converters. It is observed that for a two-stage conversion architecture, apart from the 2Nf-{sw} grid-current harmonics, characteristic of a cascaded multilevel converter, some lower order switching frequency based harmonics remain. On the other hand, for the single-stage conversion architecture counterpart, the dominant switching frequency based grid-current harmonics appear at 2 f-{sw} • The respective power balance control (PBC) schemes for the two conversion architectures are found to be effective, and the PBC reinforced single-stage converter displays lower grid-side current's THD compared to its two-stage counterpart. A suitable experimental verification of the implemented PBC strategy on two-stage and single-stage cascaded converter topologies is presented to demonstrate their comparative performance. © 2022 IEEJ-IAS.