Department of Electrical Engineering

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IIT Jodhpur

In this letter, a highly selective narrowband bandpass filter (BPF) is presented in substrate integrated waveguide (SIW) technology. Higher order TE301 resonators are used to utilize their high unloaded Q-factors. A midline feeding scheme together with a bypass coupling provides three transmission zeros (TZs). Two of the zeros can be placed at band edges for high selectivity. A three-pole BPF with 3-dB fractional bandwidth of 1.1% at f0 = 8.25 GHz is fabricated. It provides at least 35-dB attenuation over 2 GHz above and below the passband starting from f0 ± 0.15 GHz. © 2001-2012 IEEE.

World University root node

IEEE Microwave and Wireless Components Letters

Narrowband Substrate Integrated Waveguide Bandpass Filter with High Selectivity

Modern power system involves growing use of open channel communication in secondary frequency regulation which introduces time delay in the automatic generation control loop which may lead to system instability. This study proposes a novel power system frequency stabiliser (PSFS) which is a modified secondary controller in order to improve the system stability in the presence of large communication delays. An auxiliary signal is added to the secondary controller to provide additional damping. The gain of the controller is obtained by meta-heuristic methods. The proposed controller is first developed on a single area hydropower system and the same is then applied on the Western System Coordinating Council 3-machine, 9-bus power system. Furthermore, to show the effectiveness of the proposed PSFS in a large practical multi-area system; it is also applied to the IEEE 39-bus system. Results show that the proposed controller significantly improves the stability of a power system operating with large communication delay which is first considered as constant and then the stability improvement with the proposed PSFS in the presence of random communication delays is also shown. The PSFS performance is tested by the results obtained with MATLAB/Simulink simulations and further verified on a real-time simulator. © The Institution of Engineering and Technology 2018.

IET Generation, Transmission and Distribution

Power system frequency stabiliser for modern power systems

A metallo-hydrogel based on histidine and Zn2+ ions is designed using coordination driven self-assembly. The hydrogel formation is instantaneous and it exhibits stimuli-responsive behaviour with respect to pH, heat and external chemicals. The gelation ability depends on the optical purity and enantiomeric excess of the amino acids. The supramolecular chirality mediated by the Zn-histidine complex and subsequent fiber formation showed sign inversion of the CD signal with respect to that of native amino acids (L- or D-) and can be tuned by changing the ratio of the two chiral species, L-, D-amino acids. The Job's plot from the circular dichroism probing supramolecular chirality confirms the 1:1 complex of Zn and histidine. The viscoelastic properties and kinetics of the hydrogel can conveniently be tuned by changing its enantiomeric excess (ee\%), concentration and the ratio of Zn and histidine. Moreover, the resulting metallo-hydrogel is thixotropic and exhibits instantaneous, intrinsic self-healing behaviour.

NEW JOURNAL OF CHEMISTRY

Chirality control of multi-stimuli responsive and self-healing supramolecular metallo-hydrogels

In computer vision and graphics, various types of symmetries are extensively studied since symmetry present in objects is a fundamental cue for understanding the shape and the structure of objects. In this work, we detect the intrinsic reflective symmetry in triangle meshes where we have to find the intrinsically symmetric point for each point of the shape. We establish correspondences between functions defined on the shapes by extending the functional map framework and then recover the point-to-point correspondences. Previous approaches using the functional map for this task find the functional correspondences matrix by solving a non-linear optimization problem which makes them slow. In this work, we propose a closed form solution for this matrix which makes our approach faster. We find the closed-form solution based on our following results. If the given shape is intrinsically symmetric, then the shortest length geodesic between two intrinsically symmetric points is also intrinsically symmetric. If an eigenfunction of the Laplace-Beltrami operator for the given shape is an even (odd) function, then its restriction on the shortest length geodesic between two intrinsically symmetric points is also an even (odd) function. The sign of a low-frequency eigenfunction is the same on the neighboring points. Our method is invariant to the ordering of the eigenfunctions and has the least time complexity. We achieve the best performance on the SCAPE dataset and comparable performance with the state-of-the-art methods on the TOSCA dataset. © 2018, Springer Nature Switzerland AG.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Fast and Accurate Intrinsic Symmetry Detection

This paper presents an adaptive control approach based on a novel multilayer fifth-order generalized integrator (MFOGI) and single-input fuzzy-tuned proportional-integral (PI) controller for single-phase two-stage grid-connected partially shaded solar photovoltaic (PV) system, where the global maximum power point (GMPP) is tracked by using a novel human psychology optimization (HPO) algorithm. The MFOGI is used to extract the fundamental component from the grid voltage, even when the grid voltage is characterized by undervoltage, overvoltage, severe harmonics distortion, frequency variations, direct current (dc) offset, etc., on a wide range. Moreover, the single-input fuzzy-tuned PI controller is used for online PI controller gains tuning during different disturbances and dynamic conditions. To ensure a fast dynamic response, a PV feed-forward component is also included in the control algorithm as well as HPO is developed for quick GMPP tracking (GMPPT). The proposed control is modeled and simulated in MATLAB platform, as well as tested on a developed prototype in the laboratory. During simulation and testing, overvoltage, undervoltage, severe harmonics distortion, and dc offset in grid voltage, as well as insolation and temperature variations on PV array are considered. The total harmonic distortions in grid current, during the different complex disturbances and dynamic situations, are found very less, in comparison to the state-of-the-art techniques and IEEE-519 standard, as well as due to the HPO algorithm, the GMPPT time is very less, which shows the superiority over state-of-the-art techniques. © 2005-2012 IEEE.

IEEE Transactions on Industrial Informatics

Implementation of Multilayer Fifth-Order Generalized Integrator-Based Adaptive Control for Grid-Tied Solar PV Energy Conversion System

In this letter, we study the physical layer secrecy performance of the classic Wyner's wiretap model over double Rayleigh fading channels for vehicular communications links. We derive novel and closed-form expressions for the average secrecy capacity (ASC) taking into account the effects of fading, path loss, and eavesdropper location uncertainty. The asymptotic analysis for ASC is also conducted. The derived expressions can be used for secrecy capacity analysis of a number of scenarios including vehicular-to-vehicular (V2V) communications. The obtained results reveal the importance of taking the eavesdropper location uncertainty into consideration while designing V2V communication systems. © 2012 IEEE.

Fulltext

IEEE Wireless Communications Letters

On Physical Layer Security of Double Rayleigh Fading Channels for Vehicular Communications

A robust continuous control for tracking a step reference signal without any overshoot and arbitrarily small rise time is proposed for a linear multivariable system. Integral sliding mode technique with the super-twisting sliding mode is used to make the control robust against the matched disturbances with bounded derivatives. Moore's eigenstructure assignment is used to compute nominal control part of the integral sliding mode technique which makes the system output to track the step reference with arbitrarily small rise time and without any overshoot under some mild assumptions. The efficacy of the proposed control is validated using simulation results on benchmark quadruple tank model. © The Institution of Engineering and Technology 2018.

IET Control Theory and Applications

Robust non-overshooting tracking using continuous control for linear multivariable systems

BiFeO3 thin films are deposited on FTO coated glass substrates using a simple sol-gel process, limiting thickness about 70 nm and Ag/BiFeO3/FTO RRAM devices are prepared. The devices showed low-voltage bipolar switching with the maximum Ion/Ioff ratio ∼450, and low set and reset voltages ∼1.1 V and −1.5 V, respectively. The devices are stable against on-off cycles with ∼104 s retention time without any significant degradation. The variations in the set and reset voltages are 0.4 V and 0.6 V, respectively. We found that ohmic and trap-controlled space charge limited conductions are responsible for low and high resistance states, respectively. The resistive switching mechanism is attributed to the formation and rupturing of the metal filament during the oxidation and reduction of Ag ions for the set and reset states. The devices showed strong robustness against environmental conditions even after ten months from their synthesis and first measurements, exhibiting good reproducibility, retention and endurance. © 2018 Elsevier Ltd

Department of Physics

Superlattices and Microstructures

Robust non-volatile bipolar resistive switching in sol-gel derived BiFeO3 thin films

The physical mechanism of highly efficient photoluminescence (PL) emission from p-type silicon is described by a comparative study of the effectiveness of the etching parameters in an electrochemical anodization technique. Two series of porous silicon samples were prepared in a combination of anodization current and time, to maintain the total amount of anodic charge transfer constant. Photoluminescence studies show that irrespective of the amount of charge transfer, the samples prepared with comparatively higher current density show an efficient PL as well as stronger blueshift in the emission energy vis-à-vis the samples prepared for longer durations. An overall decrease in crystallite size, as estimated by Raman spectral analysis, was observed for both series of samples with the progress of charge transfer. Comparative analysis shows a marginal difference in crystallite size for both series of samples in the initial state of charge transfer, whereas major differences arise at higher values. This is explained with the formation of silicon suboxide on the porous surface at higher current density, leading to initiation of side wall reaction, and higher reduction rate in crystallite size as well as strong luminescence due to the carrier quantum confinement effect. © 2017, Springer Science+Business Media Dordrecht.

Silicon

Efficient PL Emission from p-type Porous Silicon: A Comparative Study for Selection of Effective Anodization Parameters

In this paper, design of Substrate Integrated Coaxial Line (SICL) fed printed dipole antenna for Ka band application is demonstrated. The proposed antenna efficiently utilizes the out of phase surface current in the central and outer conductor of the SICL to excite the dipole antenna. The use of SICL removes the need of using balun to feed the dipole antenna and makes the feeding network simpler. The metal plate at the top layer acts as reflector for the dipole antenna which helps to enhance the gain of the antenna upto 5.38 dBi with a broad bandwidth of 2.37 GHz. The antenna is implemented in low profile planar substrate making it suitable for practical application in Ka band. © 2017 IEEE.