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ADAPTIVITY IN SPACE AND TIME FOR MAGNETOQUASISTATICS

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Journal of Computational Mathematics 2009年第5期27卷 642-656页

作者： Markus Clemens jens Lang Delia Teleaga Georg Wimmer Helmut-Schmidt-Universitat Hamburg Holstenhofweg 8522043 HamburgGermany Technische Universitat Darmstadt Schlossgartenstraβe 764289 DarmstadtGermany

This paper addresses fully space-time adaptive magnetic field computations. We describe an adaptive Whitney finite element method for solving the magnetoquasistatic formulation of Maxwell＇s equations on unstructured 3D tetrahedral grids. Spatial mesh re- finement and coarsening are based on hierarchical error estimators especially designed for combining tetrahedral H（curl）-conforming edge elements in space with linearly implicit Rosenbrock methods in time. An embedding technique is applied to get efficiency in time through variable time steps. Finally, we present numerical results for the magnetic recording write head benchmark problem proposed by the Storage Research Consortium in Japan.

关键词： Magnetoquasistatics Space-time adaptivity Edge elements Rosenbrock meth-ods Hierarchical error estimator SRC benchmark problem.

Using resistance distance from circuit theory to model dispersal through habitat corridors

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Journal of Plant Ecology 2018年第3期11卷 385-393页

作者： Jan Thiele Sascha Buchholz jens Schirmel Institute of Landscape Ecology University of MünsterHeisenbergstr.2Münster 48149Germany Department of Ecology TU BerlinRothenburgstr.12Berlin 12165Germany Berlin-brandenburg Institute of Advanced Biodiversity Research(BBIB) Altensteinstr.34Berlin 14195Germany Institute of Environmental Sciences University Koblenz-LandauFortstr.7Landau 76829Germany

Aims Resistance distance(RD),based on circuit theory,is a promising metric for modelling effects of landscape configuration on dispersal of organ-isms and the resulting population and community *** values of RD reflect the likelihood of a random walker to reach from a source to a certain destination in the *** it has successfully been used to model genetic structures of animal populations,where it most often outperforms other isolation metrics,there are hardly any applications to plants and,in particular,to plant community *** aims were to test if RD was a suitable metric for studying dispersal processes of plants in narrow habitat corridors(linear landscape ele-ments[LLE]).This would be the case,if dispersal processes(seed dis-persal and migration)resembled random ***,we compared the model performance of RD against least-cost distance(LCD)and Euclidean distance(ED).Finally,we tested the suitability of different cost surfaces for calculations of LCD and *** We used data from 50 vegetation plots located on semi-natural LLE(field margins,ditches,road verges)in eight agricultural landscapes of Northwest *** mapped LLE,including hedges and tree rows,from aerial images in a Geographic Information System,con-verted the maps into raster layers,and assigned resistance values to the raster cells,where all cells outside of LLE received infinite resist-ance and,thus,represented barriers to *** all pairs of plots within study areas,we calculated Jaccard similarity assuming that it was a proxy(or correlate)of dispersal events between ***,we calculated RD and LCD of the network of LLE and ED between the *** modelled the effects of distance metrics on community similarity using binomial generalized linear mixed *** Findings ED was clearly the least suitable isolation ***,we found that RD performed better than LCD at modelling Jaccard *** varied markedly betwee

关键词： connectivity floristic similarity isolation landscape migration least-cost distance

Fully integrated and broadband Si-rich silicon nitride wavelength converter based on bragg scattering intermodal four-wave mixing

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Photonics Research 2024年第3期12卷 I0001-I0010页

作者： VALERIO VITALI THALÍA DOMÍNGUEZ BUCIO HAO LIU JOSÉMANUEL LUQUE GONZÁLEZ frANCISCO JURADO-ROMERO ALEJANDRO ORTEGA-MOÑUX GLENN CHURCHILL JAMES C.GATES JAMES HILLIER NIKOLAOS KALFAGIANNIS DANIELE MELATI jens H.SCHMID ILARIA CRISTIANI PAVEL CHEBEN J.GONZALO WANGÜEMERT-PÉREZ ÑIGO MOLINA-FERNÁNDEZ frEDERIC GARDES COSIMO LACAVA PERIKLIS PETROPOULOS Optoelectronics Research Centre University of SouthamptonSouthampton SO171BJUK Electrical Computer and Biomedical Engineering DepartmentUniversity of PaviaPavia 27100Italy Telecommunication Research Institute(TELMA) Universidad de MálagaCEI Andalucı´a TECHE.T.S.I.Telecomunicación29010 MálagaSpain School of Science and Technology Nottingham Trent UniversityNottingham NG118NSUK Department of Electrical Engineering Eindhoven University of TechnologyEindhoven 5600 MBThe Netherlands Department of Materials Science and Engineering University of IoanninaIoannina 45110Greece Centre de Nanosciences et de Nanotechnologies UniversitéParis-SaclayCNRS91120 PalaiseauFrance Advanced Electronics and Photonics Research Center National Research Council CanadaOttawaOntario K1A 0R6Canada

Intermodal four-wave mixing(FWM)processes have recently attracted significant interest for all-optical signal processing applications thanks to the possibility to control the propagation properties of waves exciting distinct spatial modes of the same *** allows,in principle,to place signals in different spectral regions and satisfy the phase matching condition over considerably larger bandwidths compared to intramodal ***,the demonstrations reported so far have shown a limited bandwidth and suffered from the lack of on-chip components designed for broadband manipulation of different *** demonstrate here a silicon-rich silicon nitride wavelength converter based on bragg scattering intermodal FWM,which integrates mode conversion,multiplexing and de-multiplexing functionalities *** system enables wavelength conversion between pump waves and a signal located in different telecommunication bands(separated by 60 nm)with a 3 dB bandwidth exceeding 70 nm,which represents,to our knowledge,the widest bandwidth ever achieved in an intermodal FWM-based system.

关键词： scattering pump modal

A concurrent optimization approach for energy efficient multiple axis positioning tasks

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Journal of Control and Decision 2016年第4期3卷 223-247页

作者： Christian Hansen jens Kotlarski Tobias Ortmaier Institute of Mechatronic Systems Leibniz Universitat HannoverHanoverGermany

Automated production systems typically comprise numerous electrical servo drives,many of which conduct positioning motions,*** handling or manipulation *** power electronics of modern multi-axis systems often comprise coupled DC-links,enabling for internal exchange of recuperative brake ***,the motion sequences of manipulators are often commanded at maximum dynamics for minimum time motion,neglecting possible optimization potential,*** idle time,leading to inefficient energy management.A robust trajectory optimization approach based on the particle swarm algorithm and well-established path planning methods is presented for the adaption of multi-axis positioning tasks with only two parameters per axis and positioning motion during system *** results prove that,depending on the positioning task and chosen optimization constraints,energy demands are distinctly *** approach is applicable to diverse multi-axis configurations and enables for considerable energy savings without additional hardware invest.

关键词： Multiple axis systems electrical servo drive energy efficient control trajectory optimization positioning tasks

Intraspecific trait variation in three common grass species reveals fine-scale species adjustment to local environmental conditions

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Journal of Plant Ecology 2018年第6期11卷 887-898页

作者： Tina Buchmann jens Schumacher Christiane Roscher UFZ Helmholtz Centre for Environmental ResearchTheodor-Lieser-Strasse 4Halle 06120Germany Institute of Mathematics StochasticsFriedrich Schiller University JenaErnst-Abbe-Platz 2Jena 07743Germany UFZ Helmholtz Centre for Environmental ResearchPhysiological DiversityPermoserstraße 15Leipzig 04318Germany German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig Deutscher Platz 5eLeipzig 04103Germany

Aims Studies along environmental gradients have shown that intraspecific trait variation(ITV)may contribute considerably to community-level trait ***,we lack knowledge about how the extent of ITV varies on a local scale and whether a varying extent of ITV is related to differences in local environmental site and plant commu-nity *** We investigated plant height,specific leaf area(SLA),leaf dry mat-ter content(LDMC)and leaf greenness of three common grass spe-cies(Arrhenatherum elatius,Dactylis glomerata,Poa pratensis)in 12 mown grasslands in a local study area around Jena(Thuringia,Germany)across three spatially hierarchical sampling levels:between sites,between subplots within site and within *** Findings Arrhenatherum elatius and *** had higher means in plant height and a lower variation in leaf traits than *** major proportions of variation in leaf traits of *** and *** were found within subplots,while the traits of *** varied mainly between *** correlations across the hierarchical sam-pling levels were highly consistent in ***,but more variable in *** and *** site and plant commu-nity characteristics mostly explained a larger proportion of variation in trait means in *** than in *** and ***,while metrics of ITV were generally less *** results suggest that trait variation in *** and *** is more strongly related to within-site conditions(*** interactions),while differences in local environmental conditions between sites have a strong impact on trait variation in *** our study was limited to three grass species,further studies with a greater number of species are required to make generalizations about the importance of biotic interactions and environmental conditions as drivers of ITV at local scale.

关键词： grass species intraspecific trait variation leaf traits

Ethyl-iophenoxic acid as a quantitative bait marker for small mammals

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Integrative Zoology 2022年第6期17卷 981-990页

作者： Kyra JACOBLINNERT Christian IMHOLT Detlef SCHENKE jens JACOB Julius Kühn Institute(JKI) Federal Research Centre for Cultivated PlantsInstitute for Plant Protection in Horticulture and ForestsVertebrate ResearchMünsterGermany Department of Behavioral Biology University of OsnabrückOsnabrückGermany Julius Kühn Institute(JKI) Federal Research Centre for Cultivated PlantsInstitute for Ecological ChemistryPlant Analysis and Stored Product ProtectionBerlinGermany

Bait markers are indispensable for ecological research but in small mammals,most markers are invasive,expensive and do not enable quantitative analyses of ***-iophenoxic acid(Et-IPA)is a non-toxic,quantitative bait marker,which has been used for studying bait uptake in several carnivores and *** developed a bait with Et-IPA,assessed its palatability to common voles(Microtus arvalis),and determined the dose-residue-relation for this important agricultural pest rodent ***-IPA concentrations of 40 to 1280μg Et-IPA per g bait were applied to wheat using sunﬂower oil or polyethylene glycol 300 as potential *** a laboratory study,common voles were offered the bait and blood samples were collected 1,7,and 14 days after *** samples were analyzed with LC-ESI-MS/MS for blood residues of ***ﬂower-oil was the most suitable bait ***-IPA seemed to be palatable to common voles at all test ***-dependent residues could be detected in blood samples in a dose-dependent manner and up to 14 days after uptake enabling generation of a calibration curve of the dose-residue ***-IPA was present in common vole blood for at least 14 days,but there was dissipation by 33–37%depending on ***-IPA meets many criteria for an“ideal”quantitative bait marker for use in futureﬁeld studies on common voles and possibly other small mammal species.

关键词： baiting biomarker Microtus arvalis quantitative bait marker small mammals

New design paradigm for heterogeneous catalysts

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National Science Review 2015年第2期2卷 140-143页

作者： Aleksandra Vojvodic jens K.N?rskov SUNCAT Center for Interface Science and Catalysis SLAC National Accelerator Laboratory Department of Chemical Engineering Stanford University

Both scientiic discovery and technological development are at some point faced with the question of how to progress from a trial-and-error approach to a highly controlled design *** heterogeneous catalysis,the search for the optimal active site of a catalyst for a given chemical reaction has been the central objective of research for almost a ***

关键词： New design paradigm for heterogeneous catalysts

Hard-thermal-loop QED thermodynamics

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Chinese Physics C 2010年第9期34卷 1527-1529页

作者：苏楠 jens O.Andersen Michael Strickland frankfurt Institute for Advanced Studies Department of Physics Norwegian University of Science and Technology Department of Physics Gettysburg College

The weak-coupling expansion for thermodynamic quantities in thermal field theories is poorly convergent unless the coupling constant is *** discuss the calculation of the free energy for a hot gas of electrons and photons to three-loop order using hard-thermal-loop perturbation theory （HTLpt）.We show that the hard-thermal-loop perturbation reorganization improves the convergence of the successive approximations to the QED free energy at large coupling,e ～ *** reorganization is gauge invariant by construction,and due to the cancellations among various contributions,we obtain a completely analytic result for the resummed thermodynamic potential at three loops.

关键词： resummation hard-thermal-loop thermal field theory QED free Energy

An analytical validation for the attenuation of lateral propagating light in sea ice

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Acta Oceanologica Sinica 2015年第3期34卷 1-8页

作者： ZHAO Jinping LI Tao EHN jens BARBER David Physical Oceanography Laboratory Ocean University of China Centre for Earth Observation Science University of Manitoba

The attenuation of lateral propagating light （LPL） in sea ice was measured using an artificial light source in the Canadian Arctic during the 2007/2008 winter. The apparent attenuation coefficientμ（λ）for lateral prop-agating light was obtained from the measured logarithmic relative variation rate. In this study an analytical solution based on the strict optical theories is developed to validate the measured result. There is a good consistency between theoretical solution and measured data, by which a quite simple but very rigorous relationship among the light source, measurement geometry, and measured irradiance is established. The attenuation coefficients acquired by measurement and theory are the diffusion attenuation as an apparent optical property of ice, independent of the light source and shining condition. The attenuation ability of sea ice should be caused by the microstructure of sea ice, such as crystal size, ice density, brine volume, air inclusion, etc. It also includes the leak from both interfaces by directional scattering. It is verified that the measuring approach is operational and accurate to measure the attenuation of the LPL. The solution from this study did not tell the connection among the extinction and the inclusions of sea ice theoretically be-cause of insufficient understanding.

关键词： Arctic,sea ice lateral propagating light optical attenuation coefficient artificial light analytical solution