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Quick Line Outage Identification in Urban Distribution Grids via Smart Meters

CSEE Journal of Power and Energy Systems 2022年第4期8卷 1074-1086页

作者： Yizheng Liao Yang Weng Cin-Woo Tan Ram RAJAGOPAL Department of Civil and Environmental Engineering Stanford UniversityStanfordCA94305USA School of Electrical Computingand Energy EngineeringArizona State UniversityTempeAZ85287USA

The growing integration of distributed energy resources(DERs)in distribution grids raises various reliability issues due to DER's uncertain and complex behaviors.With large-scale DER penetration in distribution grids,traditional outage detection methods,which rely on customers report and smart meters'“last gasp”signals,will have poor performance,because renewable generators and storage and the mesh structure in urban distribution grids can continue supplying power after line outages.To address these challenges,we propose a datadriven outage monitoring approach based on the stochastic time series analysis with a theoretical guarantee.Specifically,we prove via power flow analysis that dependency of time-series voltage measurements exhibits significant statistical changes after line outages.This makes the theory on optimal change-point detection suitable to identify line outages.However,existing change point detection methods require post-outage voltage distribution,which are unknown in distribution systems.Therefore,we design a maximum likelihood estimator to directly learn distribution parameters from voltage data.We prove the estimated parameters-based detection also achieves optimal performance,making it extremely useful for fast distribution grid outage identifications.Furthermore,since smart meters have been widely installed in distribution grids and advanced infrastructure(e.g,PMU)has not widely been available,our approach only requires voltage magnitude for quick outage identification.Simulation results show highly accurate outage identification in eight distribution grids with 17 configurations with and without DERs using smart meter data.

关键词： Power distribution network outage detection outage identification voltage measurement change point detection graphical model

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Incentive mechanism for sharing distributed energy resources

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Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 837-850页

作者： Jianxiao WANG Haiwang ZHONG Junjie QIN Wenyuan TANG Ram RAJAGOPAL Qing XIA Chongqing KANG Department of Electrical Engineering Tsinghua UniversityBeijing 100084China Department of Electrical Engineering and Computer Sciences University of CaliforniaBerkeleyCA 94720-1776USA Department of Electrical and Computer Engineering North Carolina State UniversityRaleighNC 27695USA Department of Civil and Environmental Engineering Stanford UniversityStanfordCA 94305USA

To improve the controllability and utilization of distributed energy resources(DERs),distribution-level electricity markets based on consumers’bidding and offers have been proposed.However,the transaction costs will dramatically increase with the rapid development of DERs.Therefore,in this paper,we develop an energy sharing scheme that allows users to share DERs with neighbors,and design a novel incentive mechanism for benefit allocation without users’bidding on electricity prices.In the energy sharing scheme,an aggregator organizes a number of electricity users,and trades with the connected power grid.The aggregator is aimed at minimizing the total costs by matching the surplus energy from DERs and electrical loads.A novel index,termed as sharing contribution rate(SCR),is presented to evaluate different users’contributions to the energy sharing.Then,based on users’SCRs,an efficient benefit allocation mechanism is implemented to determine the aggregator’s payment to users that incentivize their participation in energy sharing.To avoid users’bidding,we propose a decentralized framework for the energy sharing and incentive mechanism.Case studies based on real-world datasets demonstrate that the aggregator and users can benefit from the energy sharing scheme,and the incentive mechanism allocates the benefits according to users’contributions.

关键词： Distributed energy resource(DER) Energy sharing Incentive mechanism Nash bargaining

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An Evolutionary Approach to Improve the Beam Steering Performance over Conventional Approach in CHAA

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Journal of Communications and Information Networks 2023年第2期8卷 164-170页

作者： K Akhitha Gopi ram National Institute of Technology Warangal 506004India

In this work,evolutionary algorithms are applied for the first time to achieve better radiation characteristics over the conventional beamforming algorithm in the concentric hexagonal antenna array(CHAA),which improves the performance of wireless communication.Multiple signal classification(MUSIC)algorithm is employed for direction of arrival(DoA)estimation.The conventional adaptive beam steering algorithm,least mean-square(LMS)algorithm,is used to steer the beam.Further,the proposed approach is employed by novel particle swarm optimization(NPSO)to reduce sidelobe level(SLL)even further.A six-ring CHAA with 126 elements for DoA estimation and beam steering is simulated.The simulation results of the MUSIC,LMS,NPSO,and particle swarm optimization(PSO)algorithms are provided for various DoAs.

关键词： smart antenna hexagonal array PSO MUSIC algorithm LMS algorithm DoA estimation beam steering NPSO

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State of the art review on physiochemical and engineering characteristics of fly ash and its applications

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International Journal of Coal Science & Technology 2022年第1期9卷 21-45页

作者： Amit Kumar ram Supriya Mohanty Department of Civil Engineering Indian Institute of Technology(Banaras Hindu University)Varanasi 221005India

The focus of this study is to critically review the physiochemical and engineering properties of the fly ash and its applications in various fields.The utilization of fly ash has become a widespread area,but the amount of utilization is still a serious issue.It has many beneficial qualities(such as pozzolanic property,fineness,spherical shape,lightweight,etc.),which enhance its properties and make it suitable for its utilization as a new construction material.For the bulk utilization of fly ash,it should be employed in the areas independent of any other parameters.So that,the disposal problem can be reduced significantly.The knowledge of its physiochemical characteristic helps in the judgment of appropriate fly ash for any particular type of work.Fly ash can be utilized in other areas such as asphalt concrete,geopolymer concrete,ground improvement,agricultural sector,roller compacted concrete,brick,etc.that will reduce the existing ashes,and also the disposal problem can be solved appreciably.The implementation of fly ash must be avoided below the natural ground water level and below 4°C temperature conditions.

关键词： Fly ash Chemical property Engineering property Construction material

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ELLIPTIC RECONSTRUCTION AND A POSTERIORI ERROR ESTIMATES FOR FULLY DISCRETE SEMILINEAR PARABOLIC OPTIMAL CONTROL PROBLEMS

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Journal of Computational Mathematics 2022年第2期40卷 147-176页

作者： ram Manohar Rajen Kumar Sinha Department of Mathematics Indian Institute of Technology GuwahatiGuwahati-781039India

This article studies a posteriori error analysis of fully discrete finite element approximations for semilinear parabolic optimal control problems.Based on elliptic reconstruction approach introduced earlier by Makridakis and Nochetto[25],a residual based a posteriori error estimators for the state,co-state and control variables are derived.The space discretization of the state and co-state variables is done by using the piecewise linear and continuous finite elements,whereas the piecewise constant functions are employed for the control variable.The temporal discretization is based on the backward Euler method.We derive a posteriori error estimates for the state,co-state and control variables in the L^(∞)(0,T;L^(2)(Ω))-norm.Finally,a numerical experiment is performed to illustrate the performance of the derived estimators.

关键词： Semilinear parabolic optimal control problem Finite element method The backward Euler method Elliptic reconstruction A posteriori error estimates

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The potential of legume-derived proteins in the food industry

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Grain & Oil Science and Technology 2022年第4期5卷 167-178页

作者： Neta Goldstein ram Reifen The Institute of Biochemistry and Nutrition The Robert H.Smith Faculty of AgricultureFood and EnvironmentThe Hebrew University of JerusalemRehovot 76100Israel

Legume-derived proteins present an opportunity to replace existing animal-source protein in various applications. Those proteins are abundant, relatively lowcost, sustainable, not highly allergenic, and widely acceptable by consumers. In this paper, it was found that legume-derived protein’s technofunctional properties(e.g. gelation, emulsification and foaming) are being investigated, in order to assess their ability to substitute for animal-derived proteins in food systems and applications. This paper reviewed the functional attributes of legume-derived proteins, their possible applications in food systems, and their potential in the food industry. The techno-functional properties of the proteins vary among different legumes, and while some proteins properties are sufficient for industrial uses, the other may need to be modified. It was concluded that legume-derived proteins could replace some existing animal-derived protein based food systems.

关键词： Legumes Plant protein Food industry Techno-functional properties Fat and protein composition

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Macro level performance study of Ahmadabad bus rapid transit system:Janmarg

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Green Energy and Intelligent Transportation 2023年第3期2卷 30-52页

作者： Sanskar Pathak ram Krishna Upadhyay Gati Shakti Vishwavidyalaya VadodaraGujarat390004India

Amidst the rapid urbanization in the country,the importance of urban public transport has been realized by the governments.Public transport is vital to the city's economy and ensures social equity.Bus Rapid Transit System(BRTS)has emerged as an exciting way to decongest the cities,enhancing and increasing mobility and accessi-bility and promoting transit-oriented development.India's longest BRTS,Janmarg,was created with similar ob-jectives.However,the system faces reduced ridership and inhibited growth because of its hidden inefficiencies.This research aims to identify all the factors affecting ridership,accessibility,and inhibiting the system's growth even after having sufficient infrastructure.It also aims to quantitatively determine whether Janmarg could achieve its establishment's objectives on the city transportation system after thirteen years of the successful implementation of the project.The research methodology used in this work combines primary and secondary research.The factors are responsible for preventing Janmarg from achieving its objectives and utilizing its full potential are determined and recommended ways to utilize adversities effectively.Results show that this study endorses reducing ambiguities and a way forward for making a sustainable transportation system.

关键词： Janmarg Ridership Travel mode Passenger behavior

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On the spatio-temporal variation in b-value after 25 April 2015 Gorkha,Nepal earthquake

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Geodesy and Geodynamics 2022年第5期13卷 525-533页

作者： ram Krishna Tiwari Harihar Paudyal Daya Shanker Central Department of Physics Tribhuvan UniversityKirtipurKathmanduNepal Birendra Multiple Campus Tribhuvan UniversityBharatpurChitwanNepal Department of Earthquake Engineering Indian Institute of Technology RoorkeeRoorkeeUttarakhandIndia

In the present study,the spatial-temporal distribution of b-value along the five faults area(the Judi fault,Thaple fault,Kathmandu fault,Motihari-Gauri Shanker fault,and Motihari-Everest fault)was investigated after the Gorkha earthquake(M7.8).The earthquake catalog of 10,500 events was prepared by compiling the published catalogs.The study area is bounded in the central Himalaya from 26.5°to 29°in latitude direction and 84°to 87°in longitude direction.The frequency magnitude distribution shows the variation of the b-value along with fault areas from 0.45 to 0.69,indicating a common characteristic of aftershock sequences.In particular,the Judi fault area,Thaple fault area,and Motihari-Everest fault area are characterized by the low b-values of 0.45±0.02,0.48±0.02,and 0.55±0.04,respectively.These regions could be the source region for future earthquakes.The low b-value observed for fault areas are also consistent with the thrust faulting pattern in the region as indicated by the focal mechanism of mainshock and major aftershocks.The temporal variation of b-value shows inevitable fluctuations during25 April to 12 May 2015.Among the area selected,the Motihari-Everest fault area is in critical strain(mechanically locked)conditions,as indicated by the stepwise energy release pattern.

关键词： Frequency-magnitude distribution Time series analysis Thrust fault Stress Central Himalaya

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Choice of precipitant and calcination temperature of precursor for synthesis of NiCo_2O_4 for control of CO–CH_4 emissions from CNG vehicles

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Journal of Environmental Sciences 2018年第3期30卷 62-71页

作者： Suverna Trivedi ram Prasad Department of Chemical Engineering &Technology Indian Institute of Technology (BHU)

Compressed natural gas（CNG）is most appropriate an alternative of conventional fuel for automobiles.However,emissions of carbon-monoxide and methane from such vehicles adversely affect human health and environment.Consequently,to abate emissions from CNG vehicles,development of highly efficient and inexpensive catalysts is necessary.Thus,the present work attempts to scan the effects of precipitants（Na2CO3,KOH and urea）for nickel cobaltite（Ni Co2O4）catalysts prepared by co-precipitation from nitrate solutions and calcined in a lean CO-air mixture at 400℃.The catalysts were used for oxidation of a mixture of CO and CH4（1：1）.The catalysts were characterized by X-ray diffractometer,Brunauer–Emmett–Teller surface-area,X-ray photoelectron spectroscopy;temperature programmedreductionandScanningelectronmicroscopycoupledwith Energy-Dispersive X-Ray Spectroscopy.The Na2CO3was adjudged as the best precipitant for production of catalyst,which completely oxidized CO-CH4mixture at the lowest temperature（T（100）=350℃）.Whereas,for catalyst prepared using urea,T（100）=362℃.On the other hand the conversion of CO-CH4mixture over the catalyst synthesized by KOH limited to 97%even beyond 400℃.Further,the effect of higher calcination temperatures of 500 and600℃ was examined for the best catalyst.The total oxidation of the mixture was attained at higher temperatures of 375 and 410℃ over catalysts calcined at 500 and 600℃ respectively.Thus,the best precipitant established was Na2CO3and the optimum calcination temperature of 400℃ was found to synthesize the Ni Co2O4catalyst for the best performance in CO-CH4oxidation.

关键词： CNG vehicular emissions CO-CH4 oxidation NiG0204 Precipitants Calcinations

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喜马拉雅东段及其周边地区地震b值和分形维数时空分布特征

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Applied Geophysics 2022年第3期19卷 458-469,472页

基于1964—2020年1373次地震(Mc=4.0),采用滑动窗口方法对喜马拉雅山脉东段及其周边地区(26°N–31°N和87°E–98°E)地震b值和分形维数时空特征进行分析。论文将研究区划分为3个子区,即A区(87°E–92°E),B区(92°E–94°E)和C区(94°... 详细信息

基于1964—2020年1373次地震(Mc=4.0),采用滑动窗口方法对喜马拉雅山脉东段及其周边地区(26°N–31°N和87°E–98°E)地震b值和分形维数时空特征进行分析。论文将研究区划分为3个子区,即A区(87°E–92°E),B区(92°E–94°E)和C区(94°E–98°E)。在A区包括尼泊尔东部,b值要高于其他区域,说明该区域可能存在高应力集聚和凹凸体。同时,A区地震具有高空间(Dc>1.5)和低时间分形维数(Dt<0.31),说明地震孕育断层接近于2维结构,且震中具有群聚群发特征。A区、C区地震b值与空间分形维度弱负相关,两者在B区则呈弱正相关。基于b值和分形维数,论文解释了喜马拉雅山脉东段孕震结构的时空变化的特征,可为理解区域强震发生规律提供理论基础。

关键词：喜马拉雅山脉东段断层 b值分形维度地震聚类

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