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Relay performance verification using fault event records

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Protection and Control of Modern Power Systems 2018年第1期3卷 235-244页

作者： swagata Das Sundaravaradan Navalpakkam Ananthan Surya Santoso Schweitzer Engineering Laboratories PullmanUSA Department of Electrical and Computer Engineering The University of Texas at AustinAustinUSA

Introduction:Event reports recorded by intelligent electronic devices(IEDs)such as digital relays and fault recorders during disturbances depict the status and system parameters of the power *** relay settings and unknown system parameters can lead to relay misoperation but information regarding these are available by performing a comprehensive analysis of fault ***,it is necessary to regularly make a comprehensive assessment of the functioning of the relay to ensure reliable *** description:The objective of this paper is to demonstrate various aspects of evaluating relay performance and verifying circuit parameters which are used in relay settings using field data in two case *** and Evaluation:While scrutinizing the relay’s operation,this paper also presents key insights on verifying circuit parameters using the same relay event ***:The lessons learned from the case studies presented in this paper will equip a protection engineer to inspect the operation of a relay during a transmission line fault,help gain a better understanding of the fault event and take possible actions to prevent future occurrence of similar events.

关键词： Event report Fault analysis Relay

Modeling of tunneling current density of GeC based double barrier multiple quantum well resonant tunneling diode

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Journal of Semiconductors 2018年第10期39卷 34-38页

作者： swagata Dey Vedatrayee Chakraborty Bratati Mukhopadhyay Gopa Sen Institute of Radio Physics and Electronics University of CalcuttaKolkata 700009India B.p.Poddar Institute of Management and Technology(ECE Dept) Kolkata 700052India

The double barrier quantum well（DBQW） resonant tunneling diode（RTD） structure made of SiGeSn/GeC/SiGeSn alloys grown on Ge substrate is analyzed. The tensile strained Ge（1-z）Cz on Si（1-x-y）GexSny heterostructure provides a direct band gap type I configuration. The transmission coefficient and tunneling current density have been calculated considering single and multiple quantum wells. A comparative study of tunnelling current of the proposed structure is done with the existing RTD structure based on GeSn/SiGeSn DBH. A higher value of the current density for the proposed structure has been obtained.

关键词： DBQW MQW RTD NDR tunneling current density

Effects of urea,metal ions and surfactants on the binding of baicalein with bovine serum albumin

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Journal of Pharmaceutical Analysis 2016年第4期6卷 256-267页

作者： Atanu Singha Roy Amit Kumar Dinda Nitin Kumar Pandey swagata Dasgupta Department of Chemistry Indian Institute of Technology

The interaction of baicalein with bovine serum albumin（BSA） was investigated with the help of spectroscopic and molecular docking *** binding affinity of baicalein towards BSA was estimated to be in order of 10~5 M^（-1） from fluorescence quenching *** ΔH°（-5.66 ＋ 0.14 kJ/mol） and positive（ΔS°）（＋ 79.96 ＋ 0.65J/mol K） indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positive ΔS°.The hydrophobic association of baicalein with BSA diminishes in the presence of sodium dodecyl sulfate（SDS） due to probable hydrophobic association of baicalein with SDS,resulting in a negative ΔS°（-40.65 ＋ 0.87 J/mol K）.Matrix-assisted laser desorption ionization/time of flight（MALDI-TOF） experiments indicate a 1：1 complexation between baicalein and *** unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime *** was observed that the presence of urea ruptured the non-covalent interaction between baicalein and *** presence of metal ions（Ag~＋,Mg^（2＋）,Ni^（2＋）,Mn^（2＋）,Co^（2＋） and Zn^（2＋）） increased the binding affinity of ligand towards *** changes in conformational aspects of BSA after ligand binding were also investigated using circular dichroism（CD） and Fourier transform infrared（FT-IR） spectroscopic *** selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1（subdomain MA） of BSA.

关键词： Bovine serum albumin(BSA) Baicalein Binding constant Fluorescence spectroscopy Molecular docking

A review of carbon dots and their composite materials for electrochemical energy technologies

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Carbon Energy 2021年第5期3卷 795-826页

作者： Yiming Liu swagata Roy Samrat Sarkar Jiaqiang Xu Yufeng Zhao Jiujun Zhang Institute for Sustainable Energy/College of Sciences Shanghai UniversityShanghaiChina

Carbon dots(CDs)and their composites as energy storage materials and electrocatalysts have emerged as new types of quasi-zero-dimensional carbon *** can provide a large specific surface area,numerous electron-electron hole pairs,adjustable heteroatom doping,rich surface functional groups,and so ***,the roles and functional mechanisms of CDs and their composite materials in the enhancement of electrochemical performance remain unclear and need to be understood in *** on the most recent literature,this paper comprehensively reviews the synthesis methods and applications of various categories of CDs and their composites as electrode materials of supercapacitors,lithium-ion batteries,sodium-ion batteries,and potassium-ion batteries,and as electrocatalysts for hydrogen evolution,oxygen evolution,and oxygen reduction reactions in metal-air batteries,fuel cells,and water *** facilitate further research and development,several important aspects related to CDs and their composite materials are summarized with analysis of the technical challenges in practical applications and discussion of the possible development perspectives.

关键词： carbon dots electrocatalysis energy storage preparation

Importance of charge self-consistency in first-principles description of strongly correlated systems

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npj Computational Materials 2021年第1期7卷 1949-1956页

作者： swagata Acharya Dimitar Pashov Alexander N.Rudenk Malte Rösner Mark van Schilfgaarde Mikhail I.Katsnelson Institute for Molecules and Materials Radboud UniversityNijmegen 6525 AJThe Netherlands Theory and Simulation of Condensed Matter King's College LondonThe StrandLondon WC2R2LSUK National Renewable Energy Laboratory Golden80401 ColoradoUSA

First-principles approaches have been successful in solving many-body Hamiltonians for real materials to an extent when correlations are weak or *** the electronic correlations become stronger often embedding methods based on first-principles approaches are used to better treat the correlations by solving a suitably chosen many-body Hamiltonian with a higher level *** success of such embedding theories,often referred to as second-principles,is commonly measured by the quality of self-energy E which is either a function of energy or momentum or ***,E should,in principle,also modify the electronic eigenfunctions and thus change the real space charge *** such practices are not prevalent,some works that use embedding techniques do take into account these *** such cases,choice of partitioning,of the parameters defining the correlated Hamiltonian,of double-counting corrections,and the adequacy of low-level Hamiltonian hosting the correlated subspace hinder a systematic and unambiguous understanding of such ***,for a large variety of correlated systems,strong correlations are largely confined to the charge *** an adequate non local low-order theory is important,and the high-order local correlations embedding contributes become *** we study the impact of charge self-consistency within two example cases,TiSez and CrBrs,and show how real space charge re-distribution due to correlation effects taken *** within a first-principles Green's function-based many-body perturbative approach is key in driving qualitative changes to the final electronic structure of these materials.

关键词： theory charge principles

A robust carbon coating of Na_(3)V_(2)(PO_(4))_(3)cathode material for high performance sodium-ion batteries

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Chinese Chemical Letters 2021年第11期32卷 3570-3574页

作者： Liying Shen Yong Li swagata Roy Xiuping Yin Wenbo Liu Shanshan Shi Xuan Wang Xuemin Yin Jiujun Zhang Yufeng Zhao College of Sciences&Institute for Sustainable Energy Shanghai UniversityShanghai 200444China

Na_(3)V_(2)(PO_(4))_(3)is a very prospective sodium-ion batteries(SIBs)electrode material owing to its NASICON structure and high reversible ***,on account of its intrinsic poor electronic conductivity,Na_(3)V_(2)(PO_(4))_(3)electrode materials confront with some significant limitations like poor cycle and rate performance which inhibit their practical applications in the energy ***,a simple two-step method has been implemented for the successful preparation of carbon-coated Na_(3)V_(2)(PO_(4))_(3)*** synthesized sample shows a remarkable electrochemical performance of 124.1 mAh/g at 0.1 C(1 C=117.6 mA/g),retaining 78.5 mAh/g under a high rate of 200 C and a long cycle-performance(retaining 80.7 mAh/g even after 10000 cycles at 20 C),outperforming the most advanced cathode materials as reported in literatures.

关键词： Sodium-ion batteries NASICON Na_(3)V_(2)(PO_(4))_(3) Cathode Carbon-coated

A Comparative Study of Closure of Tympanic Membrane Perforation between Chemical Cauterization and Fat Plug Myringoplasty

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International Journal of Otolaryngology and Head & Neck Surgery 2013年第6期2卷 248-252页

作者： Manabendra Debnath swagata Khanna Department of ENT Gauhati Medical College & Hospital Guwahati India

The purpose of closure of small dry tympanic membrane perforations is to restore the continuity of the tympanic membrane in order to improve hearing and decrease the incidence of middle ear infections. Small and cost effective procedures like Chemical Cauterization and Fat Plug Myringoplasty have been found to be effective in healing small central perforations with significant hearing improvement. A study was carried out in 69 patients with central perforations in the Department of ENT, Gauhati Medical College & Hospital for the duration of 1 year from August 11 to July 12. Out of 69 patients, 36 underwent Chemical Cauterization and 33 Fat Plug Myringoplasty. Pre-and post-operative hearing assessments of each patient were done and statistically analyzed. The success rate was found to be 83.33% and 90.9% respectively. In both groups, there was statistically significant hearing improvement with a P value 0.01. From our study, it was found that the two procedures are simple, reliable and also lessened the morbidity of the patient. Thus we recommend the use of these two official procedures for the treatment of central perforations of tympanic membrane less than 5 mm.

关键词： Fat Plug Myringoplasty Chemical Cauterization Paper Patching Central Perforations

Angiolymphoid Hyperplasia with Eosinophilia—A Case Report

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International Journal of Otolaryngology and Head & Neck Surgery 2012年第2期1卷 44-47页

作者： Pankaj Kumar Doloi swagata Khanna Department of ENT Gauhati Medical College & Hospital Guwahati Assam India ENT Head & Neck Clinic Swagat ESRI Guwahati Assam India

Angiolymphoid hyperplasia with eosinophilia is a rare, benign vascular tumor affecting principally the head and neck region of young adult females. Microscopic analysis reveals hyperplastic blood vessels lined by a hypertrophic endothelium. An inflammatory infiltrate rich in eosinophils is also present. Etiology of the lesion is unknown. Various treatment modalities have been described. We present a case successfully treated by excision and local steroid infiltration.

关键词： Angiolymphoid Hyperplasia with Eosinophilia (ALHE) Epithelioid Haemangioma Histiocytoid Haemangioma Kimura’s Disease

Corrosion Behaviour of Aluminium Engine Block in 3.5% NaCl Solution

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Journal of Materials Science and Chemical Engineering 2014年第10期2卷 52-58页

作者： M. S. Kaiser swagata Dutta Directorate of Advisory Extension and Research Services Bangladesh University of Engineering and Technology Dhaka Bangladesh Institute of Appropriate Technology Bangladesh University of Engineering and Technology Dhaka Bangladesh

In the present work, the corrosion behavior of aluminium alloy engine block in 3.5% NaCl solution was studied. The work was carried out using conventional gravimetric measurements and complemented by scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. The results obtained indicate that the main process the alloy undergoes, under the medium of exposure studied, is related to localized corrosion that takes place as a consequence of the process of alkalinization around the cathodic precipitates existing in the alloy. The alloy suffers a process of corrosion localized to the area surrounding the precipitates of the Al (Si, Mg) and Al-Mg, which resulted in hemispherical pits. This identification was confirmed by SEM and EDX analysis. No evidence was found of the formation of crystallographic pitting for exposure times up to 54 days. Gravimetric analysis confirmed that with varying exposure periods the weight loss of the alloy increases and the corrosion rate decreases with time.

关键词： Localized Corrosion Gravimetric Analysis Aluminium-Silicon Alloys SEM EDX