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Graph-theoretic algorithms for cyber-physical vulnerability analysis of power grid with incomplete information

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Journal of Modern Power systems and Clean Energy 2018年第5期6卷 887-899页

作者： Anurag K.sRIVAsTAVA Timothy A.ERNsTER Ren LIu Vignesh G.KRIsHNAN Department of Electrical Engineering and Computer science Washington State University u.s. army corps of engineers Dominion Power

A key focus recently has been on assessing therisk of a coordinated cyber-physical attack and minimizing the impact of a successful attack. Most of the cyberattackers will have limited system information and conventional power grid N-1 security analysis cannot be extended to assess the risk. Centrality measures are widely used in the network science and an attacker with incomplete information can use it to identify power system vulnerabilities by defining the system as a complex network but without real-time system measurements. This paper presents a graph theory based centrality indices for vulnerability assessment of the power system due to various bus and branch contingencies using limited system information and provides a preliminary defense mechanism to prevent such an attack. Proposed work answers the fundamental qu.s.ion of possible attack scenarios by balancing risk(limited information with low risk to get caught orhigh risk attack to access more system information) and impact(identifying contingencies with maximal impact on system operation). statistical comparisons are made between the graph theory measures compared to the corresponding DC power flow based N-X linear sensitivity measures. A unified N-X centrality based performance index is proposed and validated against the AC power flow based performance index by doing the real-time simulations of an N-3 attack scenario. Defensive mechanisms using topology-based performance indices are also presented.

关键词： Cyber-physical security Graph theory Transmission system Contingency Defense mechanism Incomplete information

Towards full predictions of temperature dynamics in McNary Dam forebay using OpenFOAM

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Water science and Engineering 2013年第3期6卷 317-330页

作者： Yu.s.i WANG Marcela POLITANO Ryan LAuGHERY IIHR-Hydroscience and Engineering The University of Iowa Iowa City u.s. army corps of engineers Walla Walla District Walla Walla

Hydroelectric facilities impact water temperature; low velocities in a reservoir increase residence time and enhance heat exchange in surface layers. In this study, an u.s.eady three-dimensional model was developed to predict the temperatm＇e dynamics in the McNary Dam forebay. The model is based on the open-source code OpenFOAM. RANs equations with the Bou.s.nesq approximation were used to solve the flow field. A： realizable k-ε model that accounts for the production of wind turbulence was developed. solar radiation and convective heat transfer at the free surface were included. The result of the model was compared with the field data collected on August 18, 2004. Changes in diurnal stratification were adequately predicted by the model. Observed vertical and lateral temperature distributions were accurately captured. Results indicate that the model can be used as a numerical tool to assess structural and operational alternatives to reduce the forebay temperature.

关键词： three-dimensional numerical simulation," water temperature," reservoir," thermal dynamics OpenFOAM McNary Dam forebay

Chinese Expert Consensus on Microvascular Protection strategy During Emergency Percutaneous Coronary Intervention Therapy in Patients With sT-elevation Myocardial Infarction

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Cardiology Discovery 2024年第1期4卷 5-14页

作者： Chinese society of Cardiology,Chinese Medical Association Editorial Board of Chinese Journal of Cardiology Muwei Li Yabin Wang Yaling Han Yun Zhang Feng Cao 不详 Fuwai Central China Cardiovascular Hospital Chinese People’s Liberation army General Hospital General Hospital of Northern Theater Command Qilu Hospital of shandong university

Microcirculatory dysfunction(CMD)typically occu.s.in patients with acute sT-segment elevation myocardial infarction during percutaneous coronary intervention,which is associated with more severe myocardial injury and a worse *** the advancement of intracoronary physiology and imaging technology,the prevention and therapeutic interventions of CMD have attracted more ***,relevant guidelines or consensus on CMD are lacking in *** current consensus summarizes the prevention and diagnostic strategies of emergency percutaneous coronary intervention-related CMD and gives suggestions to improve the prognosis of sT-segment elevation myocardial infarction patients based on evidence from recent clinical studies,guidelines,and consensus from international sources.

关键词： Myocardial infarction Microcirculation dysfunction Percutaneous coronary intervention

Numerical modeling of sediment flushing from Lewis and Clark Lake

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International Journal of sediment Research 2013年第2期28卷 182-193页

作者： Jungkyu AHN Chih Ted YANG Paul M.BOYD Daniel B.PRIDAL John I.REMus Civil and Environmental Engineering Department Seoul National UniversitySeoulRepublic of Korea Research Fellow Water Resources and Director of Hydroscience and Training Center Civil and Environmental Engineering DepartmentColorado State UniversityFort CollinsCOUSA80526 Borland Professor u.s.army corps of engineers OmahaNebraskaUSA Hydraulic Engineer sedimentation and Channel stabilization section U.S.Army Corps of EngineersOmahaNebraskaUSA Chief

Lewis and Clark Lake is located on the main stream of the Missouri *** reservoir is formed behind Gavins Point dam near Yankton,south Dakota,*** Lewis and Clark Lake reach extends about 40 km from the Gavins Point *** reservoir delta has been growing since the closure of Gavins Point dam in 1955 and has resulted in a 21%reduction of storage within the maximum pool of the *** several sediment management methods,drawdown flushing has been recommended as a possible management *** engineering viability of removing sediments deposited in the lake should be examined by numerical modeling before implementing a drawdown ***4 was used for this study and calibrated by using measured data from 1975 to *** cross-section changes and amount of flushed sediment were predicted with four hypothetical flow *** flushing efficiencies of all scenarios were estimated by comparing the ratios between water consumption and flushed sediment during flushing.

关键词： Drawdown flushing Flushing efficiency GsTARs computer model Reservoir sedimentation sediment transport Lewis and Clark Lake

Erosion rate of sand and mud mixtures

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International Journal of sediment Research 2020年第6期35卷 563-575页

作者： Chamil Perera Jarrell smith Weiming Wu David Perkey Anthony Priestas Department of Civil and Environmental Engineering Clarkson University Coastal and Hydraulics Laboratory US Army Corps of Engineers

Erosion of mixed cohesive and noncohesive sediments is studied using the erosion test instrument *** sediment mixtures are composed of well-sorted quartz sand(0.25-0.5 mm) and one of the three used mu.s.kaolinite,kaolinite-bentonite and Mississippi River *** mud contents cover from 0 to 100%.The measured data of erosion rate and bed shear stress are used to examine the segmented linear,nonlinear,and exponential erosion *** parameters of each erosion model are related to the physical properties of sediment mixtures,including clay fraction,mud fraction,mixture dry density,and mud dry *** is found that the three models can fit well with the data,and their parameters have strong relations with the mud fraction and mud dry density,to a less extent with the clay fraction,but not with the mixture dry density.

关键词： Cohesive sediments Noncohesive sediments sand and mud mixtures segmented linear model Nonlinear model Exponential model

Tunable electron and phonon properties of folded single-layer molybdenum disulfide

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Nano Research 2018年第3期11卷 1541-1553页

作者： Jie Peng Peter W. Chung Madan Dubey Raju R. Namburu Department of Mechanical Engineering University of Maryland College Park MD 20742 USA sensors & Electron Devices Directorate U.S. Army Research Laboratory Adelphi MD 20783 USA Computational & Information sciences Directorate U.S. Army Research Laboratory Aberdeen Proving Ground MD 21005 USA

A unique feature of transition metal dichalcogenides is their single-layer form, which enables folding. Although folding has been found to significantly affect the photoluminescence spectrum and some in-plane properties, only limited insight has been gained on how to modulate those properties. In this report, we examine the structure of folds of a single sheet of Mos2 and the dependence of the ground-s tate electronic and phonon transport properties on the wrapping length. As the folded structure is effectively a bilayer that terminates in a loop, the wrapping length modulates the relative size of the bilayer region to the closed loop along the edge. A combination of computational methods, including approaches based on variational mechanics, classical potentials, and density functional theory, are employed. Highly accurate calculations of the reference folded structure are first carried out to show that the folded structure is largely insensitive to the wrapping length. The folded structures are su.s.quently used to estimate the electronic band gap, which is found to vary significantly as a function of the wrapping length, and converges from below to the limit value corresponding to an infinite bilayer. The gap valu.s.range from 0.43 to 1.09 eV, with a crossover to an indirect gap, which suggests that the transitions must be lattice-assisted, similar to the transitions in the bilayer and bulk forms. However, the phonons, while affected by the formation of the folded structure, are insensitive to the wrapping length. In fact, the overall thermal transport behavior along the folding axis is unchanged. The possibility of modulating the gap value while keeping the thermal properties unchanged opens up new exciting avenu.s.for further applications of this emerging material.

关键词： molybdenum disulfide folded structure electronic band structure thermal conductivity phonon

New therapeutic target NCF1-directed multi-bioactive conjugate therapies prevent preterm birth and adverse pregnancy outcomes

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science Bulletin 2024年第16期69卷 2604-2621页

作者： Juan Cheng Xiaoyan Jia Limei Yang siqi Zhang Zhiyu Chen Qian Gui Ting Li Zedan Pu Hongbo Qi Jianxiang Zhang Chongqing Key Laboratory of Maternal and Fetal Medicine The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016China Women and Children’s Hospital of Chongqing Medical university Chongqing 401147China Department of Obstetrics The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016China Department of Pharmaceutics College of PharmacyThird Military Medical University(Army Medical University)Chongqing 400038China Department of Orthopedics The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016China Yu-Yue Pathology scientific Research Center Chongqing 400039China state Key Laboratory of Trauma and Chemical Poisoning Third Military Medical University(Army Medical University)Chongqing 400038China

Preterm birth(PTB)is a leading cause of neonatal morbidity and mortality worldwide,yet the cellular and molecular mechanisms driving this condition remain undeciphered,thus limiting discovery of new ***-depth analyses of human and mouse tissu.s.associated with PTB,in combination with cellular studies,indicated that aberrantly high-expressed neutrophil cytoplasmic factor(NCF)1 leads to oxidative distress,recruitment,and pro-inflammatory activation of neutrophils and macrophages,while sequentially overexpressed pro-inflammatory mediators induce contractions of uterine smooth muscle cells(usMCs)as well as apoptosis of usMCs and amniotic epithelial cells,thereby causing *** to these new findings,we rationally engineered an amphiphilic macromolecular conjugate LPA by covalently integrating low-molecular-weight heparin,a reactive oxygen species-responsive/scavenging component,and an anti-inflammatory *** bioengineered macromolecular conjugate can selfassemble into multi-bioactive nanoparticles(LPA NP).In a mouse model of PTB,LPA NP effectively delayed PTB and inhibited adverse pregnancy outcomes,by regulating NCF1-mediated oxidativeinflammatory cascades,i.e.,attenuating oxidative stress,inhibiting inflammatory cell activation,reducing local inflammation,and decreasing contraction/apoptosis of myometrial *** LPA NP into temperature-responsive,self-healing,and bioadhesive hydrogel further potentiated its in vivo efficacies after intravaginal delivery,by prolonging retention time,sustaining nanotherapy release,and increasing bioavailability in the placenta/***,both the conjugate/nanotherapy and hydrogel formulations exhibited excellent safety profiles in pregnant mice,with negligible side effects on the mother and offspring.

关键词： Preterm birth Neutrophil cytoplasmic factor Bioactive conjugate Nanotherapy Hydrogel therapy

Anthropogenic impacts to the sediment budget of são Francisco River navigation channel using sWAT

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International Journal of Agricultural and Biological Engineering 2015年第3期8卷 140-157页

作者： Calvin T.Creech Rafael Brito siqueira James P.selegean Carol Miller Wayne state university DetroitMichigan 48202United States Com panhia de Desenvolvimento dos Vales do são Francisco e do Parnaíba(CODEVAsF) Brasília 70830Brazil united states army corps of engineers Detroit DistrictDetroitMichigan 48226United States united states army corps of engineers Mobile Di strictMobile 36628AlabamaUnited States

The são Francisco River Basin,located in eastern Brazil,has undergone a significant amount of anthropogenic changes in the last several decades,such as agricultural expansion,irrigation activities,mining,and the construction of large ***,these changes have altered the historic sediment budget and have led to an aggradation of sediments in the navigation channel,impacting the ability to efficiently ship agricultural commodities to regional *** an effort to aid decision makers in future waterway navigation planning,an international partnership between the Brazilian government agency CODEVAsF and the us army corps of engineers(usACE)was *** this partnership a sWAT model of the 630000 km2 são Francisco River basin was developed to better understand both the historic and current sediment budget within the navigation *** sWAT model of the são Francisco River Basin was calibrated for hydrology and sediment *** discharges were calibrated at 17 Agência Nacional deÁgu.s.ANA)gages,with Nash-sutcliffe efficiency(NsE)valu.s.ranging from 0.42 to 0.75 for an eleven year *** loads were calibrated to an ANA sediment gage located in the Middle são Francisco River Navigation Channel,with a PBIAs(Percent Bias)of *** on model results,the aggradation rate of sediment in the são Francisco River and major tributaries has increased by approximately 20 Mt since Pre-European settlement of the basin(from approximately 7 Mt/a to 27 Mt/a).This increase has contributed to an impaired navigation channel due to shoaling of sandy sediments in the navigation channel.

关键词： sediment budget aggradation rate são Francisco River anthropogenic impact sWAT

Discrete-time dynamic graphical games:model-free reinforcement learning solution

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Control Theory and Technology 2015年第1期13卷 55-69页

作者： Mohammed I.ABOuHEAF Frank L.LEWIs Magdi s.MAHMOuD Dariusz G.MIKu.s.I systems Engineering Department King Fahd University of Petroleum & Mineral uTA Research Institute University of Texas at ArlingtonFort Worth Texas U.S.A. state Key Laboratory of synthetical Automation for Process Industries Northeastern University Ground Vehicle Robotics (GVR) U.S. Army TARDEC Warren MI U.S.A.

This paper introduces a model-free reinforcement learning technique that is used to solve a class of dynamic games known as dynamic graphical games. The graphical game results from to make all the agents synchronize to the state of a command multi-agent dynamical systems, where pinning control is used generator or a leader agent. Novel coupled Bellman equations and Hamiltonian functions are developed for the dynamic graphical games. The Hamiltonian mechanics are used to derive the necessary conditions for optimality. The solution for the dynamic graphical game is given in terms of the solution to a set of coupled Hamilton-Jacobi-Bellman equations developed herein. Nash equilibrium solution for the graphical game is given in terms of the solution to the underlying coupled Hamilton-Jacobi-Bellman equations. An online model-free policy iteration algorithm is developed to learn the Nash solution for the dynamic graphical game. This algorithm does not require any knowledge of the agents＇ dynamics. A proof of convergence for this multi-agent learning algorithm is given under mild assumption about the inter-connectivity properties of the graph. A gradient descent technique with critic network structures is used to implement the policy iteration algorithm to solve the graphical game online in real-time.

关键词： Dynamic graphical games Nash equilibrium discrete mechanics optimal control model-free reinforcementlearning policy iteration