Showing papers by "National Institute of Technology, Meghalaya published in 2018"

Thermally Twistable, Photobendable, Elastically Deformable, and Self-Healable Soft Crystals.

Abstract: The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4'-azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending, and elastic deformation without fracture is reported. This material is also able to self-heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo- and thermomechanical effects and self-healing capabilities of the material are rooted in reversible trans-cis isomerization of the azopyridine unit and crystal-to-crystal phase transition. Fairly isotropic intermolecular interactions and interlocked crisscrossed molecular packing secure high elasticity of the crystals.

Frequency Regulation in Deregulated Market Using Vehicle-to-Grid Services in Residential Distribution Network

Abstract: Progress in vehicle-to-grid technology opens market for electric vehicle (EV) users to participate in the emergency reliability services, such as frequency regulation (FR). EVs can be considered as a mobile energy storage, which has the potential to compensate the uncontracted power if the contracts between the market players are breached. As all the EVs will be penetrated to the distribution network, distribution power loss along with the power limit of transformer and lines must be incorporated in the EV model. In this paper, the accuracy of conventional EV model is improved by introducing distributed network characteristics to participate in FR under deregulated environment in the presence of diverse transmission links such as ac/dc links. Fractional order plus proportional plus integral plus derivative (FOPID) controller also abbreviated as PI λ D μ controller is used for coordinated control of conventional units and EVs. Flower pollination algorithm is employed to choose the controller parameters under different scenarios. Extensive simulations have been performed to validate the superiority of the proposed control strategy. Obtained results strongly suggest that FOPID controller is far superior to conventional PID controller.

A New Heuristic for $N$ -Dimensional Nearest Neighbor Realization of a Quantum Circuit

Abstract: One of the main challenges in quantum computing is to ensure error-free operation of the basic quantum gates. There are various implementation technologies of quantum gates for which the distance between interacting qubits must be kept within a limit for reliable operation. This leads to the so-called requirement of neighborhood arrangements of the interacting qubits, often referred to as nearest neighbor (NN) constraint. This is typically achieved by inserting SWAP gates in the quantum circuits, where a SWAP gate between two qubits exchanges their states. Minimizing the number of SWAP gates to provide NN compliance is an important problem to solve. A number of approaches have been proposed in this regard, based on local and global ordering techniques. In this paper, a generalized approach for combined local and global ordering of qubits have been proposed that is based on an improved heuristic for cost estimation and is also scalable. The approach can be extended to ${N}$ -dimensional arrangement of qubits, for any arbitrary values of ${N}$ . Practical constraints, however, restrict the maximum value of ${N}$ to 3. Extensive experiments on benchmark functions have been carried out to evaluate the performance in terms of SWAP gate requirements. 3-D organization of qubits shows average reductions of 6.7% and 37.4%, respectively, in the number of SWAP gates over 2-D and 1-D organizations. Also compared to the best 2-D and 1-D results reported in the literature, on the average 8.7% and 8.4% reductions, respectively, are observed.

Microwave assisted synthesis of Co3O4 and NiO nanoplates and structural, optical, magnetic characterizations

Abstract: The surfactant and template free Co3O4 and NiO nanoplates have synthesized using microwave assisted method. Synthesized Co 3 O 4 and NiO nanoplates were characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive spectrometer (EDS) for their Structural, morphological and elemental analysis respectively. The Fourier transform infrared (FTIR) spectra of both samples were recorded for the oxide compound confirmation. Optical and magnetic characterizations were studied by using UV–Visible absorption spectroscopy, photoluminescence (PL) and vibrating sample magnetometer (VSM) respectively. Average crystallite sizes for Co 3 O 4 and NiO nanoplates were found to be 21 nm and 17 nm respectively by using Debye–Scherrer’s formula. The energy band gaps for Co 3 O 4 and NiO nanoplates were calculated using Tauc plot and values are 3.3 eV and 3.1 eV respectively. BET surface areas of Co 3 O 4 and NiO nanoplates were measured to be 29 m2/g and 92 m2/g respectively. The magnetization of Co 3 O 4 and NiO nanoplates as a function of magnetic field were recorded at room temperature showing a small hysteresis loop with coercivity of ∼ 534 and ∼ 152 Oe respectively. Microwave assisted method can be useful for the synthesis of Co 3 O 4 and NiO nano morphological materials for supercapacitor application.

A Self-Reliant DC Microgrid: Sizing, Control, Adaptive Dynamic Power Management, and Experimental Analysis

Abstract: This paper presents an adaptive power management and control for a self-reliant dc microgrid powered by photovoltaic (PV) array and fuel cell stack that is escorted with the supercapacitor- and electrolyzer-based hybrid energy storage device. The prime operational impediments associated with this dc microgrid are the unpredictable variations in the PV generation and load demand, fuel starvation phenomenon of the fuel cell, the time constant associated with the electrolyzer operation, and state-of-charge limitation of the supercapacitor. In this paper, the above-mentioned issues are addressed by employing an adaptive dynamic power management strategy (ADPMS) that supervises the overall power flow in the system. The ADPMS enables the co-existence of high power density and high energy density storage devices to deliver the power flow required by the loads. The expeditious support extended by the supercapacitor helps in swift regulation of the dc-link voltage during unforeseen transient load/source power variations. The electrolyzer–fuel cell combination employed in this system can supplement a battery bank and can equip high energy density and self-reliance to the system. The set-reset flip-flop based fixed frequency current controller is simple and effective in accurately tracking the reference currents established by the ADPMS. The proposed ADPMS along with the control is validated for transient unforeseen load profiles and renewable generation changes via simulation studies and its performance is also validated through an experimental analysis on a laboratory-scale dc microgrid testbed.

Development of Phasor Estimation Algorithm for P-Class PMU Suitable in Protection Applications

Abstract: This paper proposes a phasor estimation algorithm for P-class phasor measurement unit suitable in protection applications using Hilbert transform and convolution of a signal. As the protective relay requires extracted fundamental component of the phasor for its operation, the author’s introduced an algorithm to estimate a robust phasor corresponding to the fundamental component which is close to the actual signal in ${L_{2}}$ -norm. Though IEEE C37.118.1a-2014 standard does not specify the accuracy requirements of phasor under transient condition, the performance of phasor estimator is tested under different dynamic conditions as per IEEE C37.118.1a-2014 standard. The effectiveness of proposed algorithm has also been verified on modified two area power system during fault along with the data generated by the experimental setup in laboratory. The results revealed that the proposed algorithm estimates the phasor accurately irrespective of distortion present in the sinusoidal signals. Furthermore, the proposed estimator inherently filters harmonics, immune to decaying dc components, detects sharp changes in a signal during faults, and effectively works under complex modulated conditions. The above scenario appears frequently in a power system with distributed energy sources. The simplicity, robustness, and generality of the proposed algorithm suits for wide area measurement systems to measure the voltage and current phasors during disturbance in the smart power system networks.

Exploring the non-covalent binding behaviours of 7-hydroxyflavone and 3-hydroxyflavone with hen egg white lysozyme: Multi-spectroscopic and molecular docking perspectives.

Abstract: The interactions of bio-active flavonoids, 7-hydroxyflavone (7HF) and 3-hydroxyflavone (3HF) with hen egg white lysozyme (HEWL) have been established using differential spectroscopic techniques along with the help of molecular docking method. The characteristic dual fluorescence of 3HF due to the excited intramolecular state proton transfer (ESIPT) process is altered markedly upon binding with HEWL. Both the flavonoids quenched the intrinsic fluorescence of HEWL through static quenching mechanism while the binding affinity of 7HF was found to be greater than 3HF under experimental conditions. The binding constant (Kb) values were estimated to be in the order of 104 M−1 and decreased with the rise in temperature. The contributions of the thermodynamic parameters (ΔH° and ΔS°) revealed that hydrophobic forces along with hydrogen bonding played a crucial role in the interaction of HEWL with 7HF and 3HF respectively and this finding was aptly supported by the molecular docking studies. The donor (HEWL) to acceptors (7HF and 3HF) binding distances were calculated using the Foster's theory. The phenomena of blue shifting of the emission maxima of the residues indicated the increase in hydrophobicity around the Trp micro-environment upon addition of the flavonoids was observed from synchronous and 3D fluorescence measurements whereas REES study indicated the decrease in mobility of the Trp residues upon addition of the ligands. The CD, FTIR and thermal melting studies indicated the alteration in the structural stability of HEWL on ligand binding and it was found that the % α-helical content decreased on complexation with 7HF and 3HF respectively as compared to native state. The flavonoids were found to inhibit the enzymatic activity of HEWL. The molecular docking results and accessible surface area (ASA) calculations revealed that the flavonoids bind within the active site of HEWL. The negative ΔG° values obtained from experimental and molecular docking studies indicate the spontaneity of the interaction processes.

Efficient Mapping of Boolean Functions to Memristor Crossbar Using MAGIC NOR Gates

Abstract: Memristor is considered as a promising circuit element which can be used in many applications. Various synthesis methods for Boolean functions have been explored in the literature using memristor-based design styles. Memristor crossbar is considered as one of the most preferred structures for implementing logic functions as well as memory. In this paper, a general synthesis flow has been proposed using the MAGIC logic design style to map multioutput Boolean functions to memristor crossbars. The functions are realized as a netlist of NOR and NOT gates. Two alternate methods of evaluating the gates are used, serial and parallel, which give a tradeoff between the number of cycles and the size of the crossbar. A strategy for scheduling the gates to time steps has also been proposed to reduce the hardware overhead. The switching delays and energy requirements are estimated using SPICE simulation. Synthesis results are reported for ISCAS’85 benchmark functions that show an average reduction of 68.8% in the number of cycles, 52.8% in energy consumption, and 96.4% in the number of memristors required as compared to a very recently published work.

PCA, Kernel PCA and Dimensionality Reduction in Hyperspectral Images

Abstract: In this chapter an application of PCA, kernel PCA with their modified versions are discussed in the field of dimensionality reduction of hyperspectral images. Hyperspectral image cube is a set of images from hundreds of narrow and contiguous bands of electromagnetic spectrum from visible to near-infrared regions, which usually contains large amount of information to identify and distinguish spectrally unique materials. In hyperspectral image analysis, reducing the dimensionality is an important step where the aim is to discard the redundant bands and make it less time consuming for classification. Principal component analysis (PCA), and the modified version of PCA, i.e., segmented PCA are useful for reducing the dimensionality. A brief detail of these PCA based methods in the field of hyperspectral images with their advantages and disadvantages are discussed here. Also, dimensionality reduction using kernel PCA (one of the non linear PCA) and its modification i.e., clustering oriented kernel PCA in this field are elaborated in this chapter. Advantages and disadvantages of all these methods are experimentally evaluated over few hyperspectral data sets with different performance measures.

Mechanochemical Synthesis of Olanzapine Salts and Their Hydration Stability Study Using Powder X-ray Diffraction

Abstract: A series of olanzapine (OLN) dicarboxylic acid salts including earlier reports on olanzapinium malonate (1:1) and maleate (1:1 and 1:2) were prepared mechanochemically using liquid assisted grinding (LAG) in order to study their hydration stability. Powder X-ray diffraction was used as a characterization tool during the investigation. On the basis of the single crystal structures of respective OLN salts, a negative correlation between the dicarboxylic acid chain length and the hydration stability of the corresponding OLN salt was found. Our observations suggest that the overall crystal packing, beyond the stronger hydrogen bond synthon (N+–H···O– in OLN salts compared to O–H···N in OLN hydrates) plays an important role in designing OLN salts with better hydration stability. In addition, melting point analysis showed that OLN dicarboxylic acid salts follow melting point alteration behavior similar to the pure diacids.

Synthesis of Au-V2O5 composite nanowires through the shape transformation of a vanadium(III) metal complex for high-performance solid-state supercapacitors

Abstract: A simple redox transformation between a vanadium(III) metal complex and gold(III) chloride aided by a cost-effective modified hydrothermal procedure has been adopted for the synthesis of Au-V2O5 composite nanowires. The stability of pseudocapacitive electrode materials in acidic electrolytes is a major challenge. However, the synthesized Au-V2O5 composite nanowires are stable in acidic electrolyte when compared to the precursor component, V2O5. Electrochemical measurement shows a specific capacitance of 419 F g−1 at 1 A g−1 current density in 0.5 M H2SO4 solution for the synthesized composite nanowires. However, the precursor component V2O5 shows a lower specific capacitance under identical conditions. The synthesized composite nanowires, as a pseudocapacitive electrode material, respond to a wide range of working potential windows (+1.6 V), resulting in maximum energy and power densities of 53.33 W h kg−1 and 3.85 kW kg−1 respectively. Moreover, the Au-V2O5 nanowires show high cyclic stability (89% specific capacitance retention) for up to 5000 consecutive charge–discharge (CD) cycles at 10 A g−1 constant current density, due to the composite formation by redox transformation, which reflects the stability of the composite in acidic electrolyte.

A Robust Fault Detection and Discrimination Technique for Transmission Lines

Abstract: The complex and large power systems of modern time with distributed generation are more prone to the faults Conventionally, the zone based primary and backup protection relies mainly on the information of positive sequence impedance sensed by the relay to protect these lines The phenomena such as power swings, load encroachment, etc, can also result into low impedance and can trigger the cascade tripping of relays In this paper, we proposed a robust fault detection and discrimination (RFDD) technique for transmission lines, which utilizes a robust method of phasor estimation to compute accurate fault impedance along with a feature value extracted from the samples of voltage and current signals The effectiveness of the proposed RFDD technique has been tested and validated on IEEE 14-bus system, six generator 23-bus system and reduced NEREB 29-bus Indian power system with distributed generation using Siemens PSS/Sincal software The results from simulation explore that RFDD technique can enhance the capability of distance protection relays for the future electric grids

Characterization of non-covalent binding of 6-hydroxyflavone and 5,7-dihydroxyflavone with bovine hemoglobin: Multi-spectroscopic and molecular docking analyses.

Abstract: Flavonoids are biologically imperative compounds used as anti-oxidants, anti-cancer, anti-bacterial agents etc. The current work reports comprehensive binding studies of two important flavonoids, 6-hydroxyflavone and 5,7-dihydroxyflavone (chrysin) with bovine hemoglobin (BHb) at 298K and 308K, in aqueous medium using UV-vis spectroscopy, steady state fluorescence, circular dichroism (CD) measurements, Fourier Transform infrared spectroscopy (FT-IR) and molecular docking studies. Both 6-hydroxyflavone and chrysin can quench the intrinsic fluorescence intensity of BHb via static quenching mechanism. The values of binding constant (Kb) for BHb-chrysin complex (3.177±0.992×104M-1, at 298K) was found to be greater than that of BHb-6-hydroxyflavone complex (2.874±0.863×104M-1, at 298K) and the Kb values decreased with the rise in temperature. The thermodynamic parameters indicated that hydrophobic forces and H-bonding play crucial role in BHb-6-hydroxyflavone complexation whereas electrostatic interaction plays the major role in the binding of BHb and chrysin. The binding distances from donor BHb to the acceptor ligands (6-hydroxyflavone and chrysin) were estimated using the Foster's theory and the possibility of non-radiative energy transfer from BHb to 6-hydroxyflavone/chrysin was observed. The ligands, 6-hydroxyflavone and chrysin induced conformational change around Trp residues in BHb as confirmed by synchronous and 3D fluorescence results. CD and FT-IR studies indicated that the % α-helicity of BHb was enhanced due to 6-hydroxyflavone/chrysin binding. Both the flavonoids showed remarkable inhibitory effect towards BHb glycation. Hydrophobic probe (8-anilino-1-naphthalenesulfonic acid, ANS) displacement and molecular docking studies revealed that the ligands bind within the hydrophobic pocket of BHb.