检索结果-南通市图书馆

Time-domain Dynamic state Estimation for Unbalanced Three-phase Power systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Power systems and Clean Energy 2023年第2期11卷 446-454页

作者： Martin Pfeifer Felicitas Mueller steven de Jongh Frederik Gielnik Thomas Leibfried sören Hohmann Institute of Control systems(IRs) KarlsruheGermany Institute of Electrical Energy systems and High Voltage Technology(IEH)at the Karlsruhe Institute of Technology(KIT) 76131 KarlsruheGermany

In this paper,we present a time-domain dynamic state estimation for unbalanced three-phase power *** dynamic nature of the estimator stems from an explicit consideration of the electromagnetic dynamics of the network,i.e.,the dynamics of the electrical *** enables our approach to release the assumption of the network being in quasi-steady ***,based on the line dynamics,we derive a graphbased dynamic system *** handle the large number of interacting variables,we propose a port-Hamiltonian modeling *** on the port-Hamiltonian model,we then follow an observer-based approach to develop a dynamic *** estimator uses synchronized sampled value measurements to calculate asymptotic convergent estimates for the unknown bus voltages and *** design and implementation of the estimator are illustrated through the IEEE 33-bus *** simulations verify the estimator to produce asymptotic exact estimates,which are able to detect harmonic distortion and sub-second transients as arising from converterbased resources.

关键词： Dynamic state estimation power system harmonic observer port-Hamiltonian system static state estimation transient

Distributional responses to climate change for alpine species of Cyananthus and Primula endemic to the Himalaya-Hengduan Mountains

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2019年第1期41卷 26-32页

作者： Xie He Kevin s. Burgess Lian-Ming Gao de-Zhu Li Germplasm Bank of Wild species Kunming Institute of Botany Chinese Academy of Sciences CAs Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of Botany Chinese Academy of Sciences Kunming College of Life sciences University of Chinese Academy of Sciences department of Biology College of Letters & Sciences Columbus State University University System of Georgia

Global warming increases the vulnerability of plants, especially alpine herbaceous species, to local extinction. In this study, we collected species distribution information from herbarium specimens for ten selected Cyananthus and Primula alpine species endemic to the Himalaya-Hengduan Mountains(HHM).Combined with climate data from WorldClim, we used Maximum Entropy Modeling(MaxEnt) to project distributional changes from the current time period to 2070. Our predictions indicate that, under a wide range of climate change scenarios, the distributions of all species will shift upward in elevation and northward in latitude; furthermore, under these scenarios, species will expand the size of their range. For the majority of the species in this study, habitats are available to mitigate upward and northward shifts that are projected to be induced by changing climate. If current climate projections, however, increase in magnitude or continue to increase past our projection dates, suitable habitat for future occupation by alpine species will be limited as we predict range contraction or less range expansion for some of the species under more intensified climate scenarios. Our study not only underscores the value of herbarium source information for future climate model projections but also suggests that future studies on the effects of climate change on alpine species should include additional biotic and abiotic factors to provide greater resolution of the local dynamics associated with species persistence under a warming climate.

关键词： Global warming MaxEnt Range expansion Alpine species Himalaya-Hengduan Mountains

Preparation and surface Layer Modification of silicon Nanoparticles Dispersed in 2-Propanol

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1998年第12期15卷 928-930页

作者： ZHU Yong s.Iwasaki K.Kimura ZHANG Li-de Institute of solid state Physics Chinese Academy of SciencesHefei 230031 department of Material science Himeji Institute of TechnologyScience Garden CityKamigohriHyogo 678-12Japan

silicon nanoparticles dispersed in 2-propanol were prepared by using an arc plasma with gas flow method in a new designed home-made *** particles are composed of silicon crystal core covered by oxidized amorphous silicon *** composition of the particle surface layer can be modified by preparing the sample in different *** particles can be also obtained with different core composition and different size which we need.

关键词： preparing apparatus amorphous

Dark Contributions to h→μ^(+)μ^(-) in the Presence of a μ-Flavored Vector-Like Lepton

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2023年第4期40卷 91-94页

作者： Bibhabasu de department of Physics ICFAI University TripuraKamalghat-799210India

A simple extension of the standard model(sM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest possible explanation for the dark matter(DM) *** the real singlet scalar to be a viable DM candidate,it has been shown that the muon Yukawa coupling can have a negative contribution at the oneloop order if the 2^(nd) generation sM leptons are allowed to couple with the VLL *** stringent direct detection bounds corresponding to a real singlet scalar DM can easily be relaxed if the sM quark sector was augmented with a dimension-6 operator at some new physics(NP) scale Λ_(NP).Thus,this model presents a significant phenomenological study where the muon Yukawa coupling can be corrected within a real singlet scalar DM *** considered parameter space can be tested/constrained through the high luminosity run of the LHC(HL-LHC) and future direct detection experiments.

关键词： scalar singlet allowed

Fagus sylvatica and Quercus pyrenaica:Two neighbors with few things in common

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2023年第2期10卷 162-175页

作者： sergio de Tomás Marín Jesús Rodríguez-Calcerrada salvador Arenas-Castro Iván Prieto Guillermo González Luis Gil Enrique G.de la Riva department of Ecology Brandenburgische Technische Universität Cottbus-SenftenbergKonrad-Wachsmann-Allee 603046CottbusGermany Forest Genetics and Ecophysiology Research Group School of Forestry EngineeringUniversidad Politécnica de MadridMadridSpain Area of Ecology Botany DepartmentEcology and Plant PhysiologyFaculty of SciencesUniversidad de CórdobaCórdobaSpain Ecology department Faculty of Biology and Environmental SciencesUniversidad de LeónLeónSpain

Background:The Iberian Peninsula comprises one of the largest boundaries between Mediterranean and Eurosiberian vegetation,known as sub-Mediterranean *** ecotone hosts many unique plant species and communities and constitutes the low-latitude(warm)margin of numerous central European species which co-occur with Mediterranean *** of the main species found in this region are the Eurosiberian European beech(Fagus sylvatica L.)and the Mediterranean Pyrenean oak(Quercus pyrenaica Willd.).It remains unclear how the different physiological and adaptive strategies of these two species reflect their niche partitioning within a subMediterranean community and to what extent phenotypic variation(intraspecific variability)is driving niche partitioning across Eurosiberian and Mediterranean ***:We quantified functional niche partitioning,based on the n-dimensional hypervolume to nine traits related to resource acquisition strategies(leaf,stem and root)plus relative growth rate as an additional wholeplant trait,and the environmental niche similarity between Pyrenean oak and European ***,we analyzed the degree of phenotypic variation of both target species and its relationship with relative growth rates(RGR)and environmental *** recruitment was measured for both target species as a proxy for the average ***:species’functional space was highly segregated(13.09%overlap),mainly due to differences in niche breadth(59.7%)rather than niche replacement(25.6%),and beech showed higher trait variability,i.e.,had larger functional ***,both species shared the environmental space,i.e.,environmental niches were *** plant traits were not related to abiotic variables or RGR,neither did RGR to plant ***:Both target species share similar environmental space,however,show notably different functional resource-use strategies,promoting a high complementarity that contributes to maintaining a high functiona

关键词： Environmental niche European beech Forest dynamics Functional niche Hypervolume Pyrenean oak species coexistence sub-Mediterranean community

NATURAL BOUNDARY INTEGRAL METHOD AND ITs NEW deVELOPMENT

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2004年第2期22卷 309-318页

作者： de-haoYu LsEC InstituteofComputationalMathematicsAcademyofMathematicsandSystemScienceChineseAcademyofSciencesBeijing100080China

In this paper, the natural boundary integral method, and some related methods, including coupling method of the natural boundary elements and finite elements, which is also called DtN method or the method with exact artificial boundary conditions, domain decomposition methods based on the natural boundary reduction, and the adaptive boundary element method with hyper-singular a posteriori error estimates, are discussed.

关键词： Artificial boundary Domain decomposition Hypersingular a posteriori estimates Natural boundary integral

ANALYsIs AND EsTIMATION OF HYDRAULIC sTABILITY OF FRANCIs HYDRO TURBINE

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2004年第2期16卷 194-200页

作者： LAIXi-de schoolofEngrgyandenvironment XihuaUniversityChengdu610039Chinae-mail：tigerlai@***

With the development of large-capacity hydro turbines, the hydraulicinstability of hydro turbines has become one of the most important problems that affect the stableoperation of the hydro-electric units. The hydraulic vibration and unstable operation of Francishydro turbines are primarily caused by the unsteady pressure pulsations inside draft tubes. Theforced rotating vortex core at the runner exit and the channel vortices inside Francis turbinerunners are origins of the unsteady pressure pulsations when operating at partial load. This paperbriefly analyzes the hydraulic instability of operation caused by the vortex core and channelvortices at partial load, then, presents a way to estimate the hydraulic stability by calculation ofthe flow behavior at the runner exit. The validity of estimation is examined by comparison withexperimental data. This will be helpful to evaluate the alternative design and predict the hydraulicstability for both the prototype and model hydro turbines.

关键词： francis hydro turbines hydraulic stability vortex core performanceestimation

Distribution of the related weevil species sitophilus oryzae and s. zeamais in Brazil

在线全文

学校读者我要写书评

暂无评论

Insect science 2013年第6期20卷 763-770页

作者： Alberto s. Correa Luiz Orlando de Oliveira Lucas s. Braga Raul Narciso C. Guedes departamento de Entomologia Universidade Federal de Vicosa Vicosa Brazil departamento de Bioquimica e Biologia Molecular Universidade Federal de Vicosa Vicosa Brazil

The genus sitophilus （Coleoptera： Curculionidae） encompasses species of great economic importance as stored grain pests worldwide. Among these species, the maize and the rice weevils （sitophilus zeamais and sitophilus oryzae, respectively） are partic- ularly important in warmer climates. These two weevils exhibit closely morphological and ecological resemblance making difficult their proper identification and recognition of their distribution in grain-producing regions. Both species are recorded in south America and particularly in Brazil, but their respective distribution and prevalence were not yet assessed in the region. Therefore, several insect samples throughout Brazil were collected and subjected to morphological identification using male genitalia and also using molec- ular identification with species-specific primers designed for clear recognition of both the species. The primers were designed for the specific amplification of a gene fragment of the cytochrome oxidase subunit I, which exhibited high specificity during our prelimi- nary experiments with insects from six populations of known species （either s. zeamais or s. oryzae）. Both identification strategies provided the same results indicating preva- lence of the maize weevil s. zeamais throughout the country. Two hypotheses may explain such prevalence：（i） the likely host preference ofs. zeamais for maize because this is the most cultivated cereal in Brazil, and （ii） the prevalence ofs. zeamais in tropical regions as compared with s. oryzae, which is more disseminated in subtropical and temperate regions.

关键词： cytochrome oxidase subunit I distribution maize weevil rice weevil south America

Wireless capsule endoscopy: Perspectives beyond gastrointestinal bleeding

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第42期20卷 15664-15673页

作者： Eduardo Redondo-Cerezo Antonio Damián sánchez-Capilla Paloma de La Torre-Rubio Javier de Teresa Endoscopy Unit Department of Gastroenterology University Hospital Virgen de Las Nieves department of Gastroenterology University Hospital Virgen de Las Nieves

Wireless capsule endoscopy(CE) is a technology developed for the endoscopic exploration of the small bowel. The first capsule model was approved by the Food and Drug Administration in 2001, and its first and essential indication was occult gastrointestinal(GI) bleeding. Over subsequent years, this technology has been refined to provide superior resolution, increased battery life, and capabilities to view different parts of the GI tract. Indeed, cases for which CE proved useful have increased significantly over the last few years, with new indications for the small bowel and technical improvements that have expanded its use to other parts of the GI tract, including the esophagus and colon. The main challenges in the development of CE are new devices with the ability to provide therapy, air inflation for a better vision of the small bowel, biopsy sampling systems attached to the capsule and the possibility to guide and move the capsule with an external motion control. In this article we review the current and new indications of CE, and the evolving technological changes shaping this technology, which has a promising potential in the coming future of gastroenterology.

关键词： Wireless capsule endoscopy Obscure gastrointestinal bleeding small bowel tumors Colon capsule endoscopy Esophageal capsule endoscopy