Department of Electrical Engineering

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IIT Jodhpur

Deteriorated quality of power leads to problems, such as equipment failure, automatic device resets, data errors, failure of circuit boards, loss of memory, power supply issues, uninterrupted power supply (UPS) systems generate alarm, corruption of software, and heating of wires in distribution network. These problems become more severe when complex (multiple) power quality (PQ) disturbances appear. Hence, this manuscript introduces an algorithm for identification of the complex nature PQ events in which it is supported by Stockwell's transform (ST) and decision tree (DT) using rules. PQ events with complex nature are generated in view of IEEE-1159 standard. Eighteen different types of complex PQ issues are considered and studied which include second, third, and fourth order disturbances. These are obtained by combining the single stage PQ events such as sag & swell in voltage, momentary interruption (MI), spike, flicker, harmonics, notch, impulsive transient (IT), and oscillatory transient (OT). The ST supported frequency contour and proposed plots such as amplitude, summing absolute values, phase and frequency-amplitude obtained by multi-resolution analysis (MRA) of signals are used to identify the complex PQ events. The statistical features such as sum factor, Skewness, amplitude factor, and Kurtosis extracted from these plots are utilized to classify the complex PQ events using rule-based DT. This is established that proposed approach effectively identifies a number of complex nature PQ events with accuracy above 98%. Performance of the proposed method is tested successfully even with noise level of 20 dB signal to noise ratio (SNR). Effectiveness of the proposed algorithm is established by comparing it with the methods reported in literature such as fuzzy c-means clustering (FCM) & adaptive particle swarm optimization (APSO), Wavelet transform (WT) & neural network (NN), spline WT & ST, ST & NN, and ST & fuzzy expert system (FES). Results of simulations are validated by comparing them with real time results computed by Real Time Digital Simulator (RTDS). Different stages for design of complex PQ monitoring device using the proposed approach are also described. It is verified that the proposed approach can effectively be employed for design of the online complex PQ monitoring devices. © 2020 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.

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Fulltext

IEEE Access

Recognition of complex power quality disturbances using S-transform based ruled decision tree

Delhi, the capital of India, suffers from heavy local emissions as well as regional transport of air pollutants, resulting in severe aerosol loadings. To determine the sources of these pollutants, we have quantified the mass concentrations of 26 elements in airborne particles, measured by an online X-ray fluorescence spectrometer with time resolution between 30 min and 1 h. Measurements of PM10 and PM2.5 (particulate matter &lt;10 μm and &lt; 2.5 μm) were conducted during two consecutive winters (2018 and 2019) in Delhi. On average, 26 elements from Al to Pb made up ~25% and ~19% of the total PM10 mass (271 μg m−3 and 300 μg m−3) in 2018 and 2019, respectively. Nine different aerosol sources were identified during both winters using positive matrix factorization (PMF), including dust, non-exhaust, an S-rich factor, two solid fuel combustion (SFC) factors and four industrial/combustion factors related to plume events (Cr-Ni-Mn, Cu-Cd-Pb, Pb-Sn-Se and Cl-Br-Se). All factors were resolved in both size ranges (but varying relative concentrations), comprising the following contributions to the elemental PM10 mass (in % average for 2018 and 2019): Cl-Br-Se (41.5%, 36.9%), dust (27.6%, 28.7%), non-exhaust (16.2%, 13.7%), S-rich (6.9%, 9.2%), SFC1 + SFC2 (4%, 7%), Pb-Sn-Se (2.3%, 1.66%), Cu-Cd-Pb (0.67%, 2.2%) and Cr-Ni-Mn (0.57%, 0.47%). Most of these sources had the highest relative contributions during late night (22:00 local time (LT)) and early morning hours (between 03:00 to 08:00 LT), which is consistent with enhanced emissions into a shallow boundary layer. Modelling of airmass source geography revealed that the Pb-Sn-Se, Cl-Br-Se and SFC2 factors prevailed for northwest winds (Pakistan, Punjab, Haryana and Delhi), while the Cu-Cd-Pb and S-rich factors originated from east (Nepal and Uttar Pradesh) and the Cr-Ni-Mn factor from northeast (Uttar Pradesh). In contrast, SFC1, dust and non-exhaust were not associated with any specific wind direction. © 2020 The Authors

Department of Civil & Infrastructure Engineering

Science of the Total Environment

Real-time measurement and source apportionment of elements in Delhi's atmosphere

In this work, we address the problem of extracting high dimensional, soft semantic feature descriptors for every pixel in an image using a deep learning framework. Existing methods rely on a metric learning objective called multi-class N-pair loss, which requires pairwise comparison of positive examples (same class pixels) to all negative examples (different class pixels). Computing this loss for all possible pixel pairs in an image leads to a high computational bottleneck. We show that this huge computational overhead can be reduced by learning this metric based on superpixels. This also conserves the global semantic context of the image, which is lost in pixel-wise computation because of the sampling to reduce comparisons. We design an end-to-end trainable network with a loss function and give a detailed comparison of two feature extraction methods: pixel-based and superpixel-based. We also investigate hard semantic labeling of these soft semantic feature descriptors. © Springer Nature Singapore Pte Ltd 2020.

Communications in Computer and Information Science

Fast semantic feature extraction using superpixels for soft segmentation

Reflection symmetry is a very commonly occurring feature in both natural and man-made objects, which helps in understanding objects better and makes them visually pleasing. Detection of reflection symmetry is a fundamental problem in the field of computer vision and computer graphics which aids in understanding and representing reflective symmetric objects. In this work, we attempt the problem of detecting the 3D global reflection symmetry of a 3D object represented as a point cloud. The main challenge is to handle outliers, missing parts, and perturbations from the perfect reflection symmetry. We propose a descriptor-free approach, in which, we pose the problem of reflection symmetry detection as an optimization problem and provide a closed-form solution. We show that the proposed method achieves state-of-the-art performance on the standard dataset. © 2020 Elsevier Ltd

Pattern Recognition

3DSymm: Robust and Accurate 3D Reflection Symmetry Detection

A 12-bit, programmable hybrid ADC for CMOS image sensor is proposed in this paper. The hybrid ADC internally uses cyclic-SAR architecture and results in an area efficient and high speed design. To minimize the total column ADC area, the elements of cyclic ADC are reused for SAR operation. The 12-bit programmable ADC can be operated either in high resolution mode or high speed mode depending on the number of bits allocated per stage. The prototype CMOS image sensor is designed and fabricated in AMS 350 nm CMOS OPTO process. A three-transistor pixel architecture followed by column parallel-readout circuit is implemented in a 9 µm column pitch. A prototype 128 × 96 image sensor consumes 62.7 mW of power at 3.3 V power supply. © 2020 IEEE

Proceedings - IEEE International Symposium on Circuits and Systems

A CMOS image sensor with column-parallel cyclic-SAR ADC

This paper proposes to design a robust controller for a class of nonlinear networked control systems using aperiodic feedback information. The parameter variation and system nonlinearity are considered as sources of uncertainty. To tackle uncertainty in system dynamics, a linear robust control law is derived using optimal control theory. Two different architectures of closed-loop systems are considered. In the first one, system and controller are not collocated; instead they are interconnected by means of a shared communication network. In the second architecture, however, sensors and controller are connected through a shared communication channel. In both architectures, the feedback loop is closed through the network. To save network bandwidth, the state and input information are transmitted aperiodically through the feedback loop. To this aim, the paper adopts an event-triggered control approach to reduce the transmission overhead. We show that the designed event-triggered controller achieves a trade-off between control performance and saving network bandwidth in the presence of uncertainty. The developed control algorithm is implemented and validated numerically on a classical nonlinear system. © 2020 IEEE.

IECON Proceedings (Industrial Electronics Conference)

Robust Stabilization of a Class of Networked Nonlinear Systems via Parsimonious Communication and Actuation

This article proposes a framework to design a robust controller for a class of nonlinear networked control systems using aperiodic feedback information. Here, the nonlinearity and parameter variations of system model are considered as sources of uncertainty. To tackle the uncertainty in system dynamics, a linear robust control law is derived by applying the optimal control theory. Two different architectures of closed-loop systems are considered. In the first one, system and controller are not collocated; instead they are interconnected by means of a shared communication network. In the second architecture, system, controller and actuator are all collocated with their respective outputs available at all time - instead, sensors and controller are connected through a shared communication channel. In both architectures, the feedback loop is closed through the network. Owing to its shared nature, the network may suffer from bandwidth limitations. To save the network bandwidth, state and input information are transmitted aperiodically within the feedback loop. With this aim, the paper adopts an event-triggered control technique so as to reduce the transmission overhead. Applying Input-to-State Stability theory, we derive two different event-triggered robust control laws that stabilize the uncertain nonlinear system. Finally, we show that the designed event-triggered controllers satisfy the trade-off between control performance and saving in network bandwidth in the presence of uncertainty. The developed control algorithm is implemented and validated through numerical simulations. © 2013 IEEE.

Robust stabilization of a class of nonlinear systems via aperiodic sensing and actuation

Nuclear wastes contain high nitrate concentration along with radionuclides like U (VI). Also, several reports suggest the presence of U (VI) and nitrate as co-contaminants in groundwater. The denitrifying bacteria consortia at MFC cathode produced phosphatase enzyme, which catalyzed the controlled release of phosphate from glycerol 3 phosphate. The inorganic phosphate combined with U (VI) resulting in insoluble uranyl phosphate. Ninety percent of initial U (VI) added in the biocathode could be recovered as Uranyl phosphate. XRD analysis confirmed the presence of uranyl phosphate precipitating at the cathode. Nitrate acted as an electron acceptor at the cathode, enabling completion of the MFC circuit and simultaneous nitrate and U (VI) removal. Since the process was performed in the MFC; the remediation was accompanied by power output. The power density of 2.91 Wm−3 and nitrate removal rate of 0.130 kg NO3−-N m−3 d−1 was achieved. The 16S rDNA based community analysis revealed a high abundance of Pseudomonas species in biocathode. This study demonstrates the applicability of MFC for simultaneous nitrate and U (VI) removal while producing electrical energy. © 2020 Elsevier B.V.

Department of Bioscience & Bioengineering

Chemical Engineering Journal

Microbial fuel cell for simultaneous removal of uranium (VI) and nitrate

A four port dipole antenna array at sub-6 GHz band (3400-3600 MHz) for mobile phone application with enhanced coverage efficiency is presented in this paper. Here a method for characterizing multiple dipole antenna in a cellular handset has been introduced. Coverage efficiency is studied for the antenna topology for its performance analysis. The array consists of four antennas placed along the four edges of the substrate. The dipole antennas placed at the oppositely faced edges are similar in dimension i.e. antenna 1 3 and antenna 2 4 are of same dimension and thus the antenna in opposite locations radiate in same manner. A common ground plane is used at the center of the substrate to isolate the antennas and also reduces mutual coupling between the antennas. The ground plane also helps in increasing the gain of the antenna. The dipole antennas 1 and 3 exhibit a fractional bandwidth of 8.47% and gain of 3.8 dBi providing vertical polarization and the dipole antennas 2 and 4 exhibit a fractional bandwidth of 6.2% and gain of 6.1 dBi providing horizontal polarization. Thereby the proposed array covers most part of the azimuthal plane. This antenna system may find its application in 5G MIMO systems particularly in smartphone applications at sub-6 GHz band. © 2020 Indian Radio Science Society.

2020 URSI Regional Conference on Radio Science, URSI-RCRS 2020 - Proceedings

Design of Printed Dipole Antenna for Enhanced Coverage Efficiency

In this Letter, a novel compact slot antenna has been realised using substrate integrated coaxial line (SICL) cavity. SICL technology helps to achieve cavity size of 0.41λ0 × 0.48λ0 while maintaining its inherent advantage of self shielded and low loss transmission line at millimetre frequencies. A SICL cavity is designed by shorting the middle conductor at the two edges and keeping the other two edges separated from the sidewall. The eigenmode analysis affirms the presence of a dominant TEM mode at 28 GHz along with the presence of SICL even and odd modes. A half wavelength diagonal slot is etched on the bottom plate of the cavity to disturb the TEM mode surface current at 28 GHz. Measurement results show the SICL cavity backed slot antenna exhibits a gain of 5.6 dBi at 28.6 GHz and high front-to-back ratio better than 17 dB. The SICL-based cavity exhibits millimetre wave resonance with much smaller size, which helps to improve the compactness of the design. The proposed antenna can be used for millimetre wave applications like handheld mobile devices at millimetre-wave frequencies. © 2020 The Institution of Engineering and Technology.