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Frequency-selective Optimization of Periodic Gate Control Signals in DC/DC Converters for EMI-reduction

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Chinese Journal of Electrical Engineering 2022年第4期8卷 11-18页

作者： Caroline Krause stephan Frei On-board Systems Lab TU Dortmund UniversityDortmund 44227Germany

High-frequency switching of power transistors in power electronic systems can cause electromagnetic *** approaches for reducing high-frequency disturbances,such as inserting an additional gate resistor,lead to increased power *** makes achieving both electromagnetic compatibility and power efficiency *** gate drivers help to find a trade-off between these ***,only narrow-band disturbances must be ***,a target signal with a spectrum notched at some frequencies can be *** target signal can be reached by a target-signal-oriented control of the transistor’s *** leads to steeper switching slopes,such that the power losses are less *** arbitrary target signals is *** transistor signal exhibits some physical limitations.A constraint satisfaction problem must be solved,and the gate drive signal must be optimized by applying a residual and Newton’s *** proposed optimization process in the frequency domain is based on the circuit simulation method named“harmonic balance”.Measurements on a DC/DC converter exhibit the benefits of this method.

关键词： Power electronics active gate driving electromagnetic compatibility Newton’s method

THE HP-VERSION OF BEM-FAST CONVERGENCE,ADAPTIVITY AND EFFICIENT PRECONDITIONING

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Journal of Computational Mathematics 2009年第2期27卷 348-359页

作者： Ernst P.stephan Institute of Applied Mathematics Leibniz University HannoverGermany

In this survey paper we report on recent developments of the hp-version of the boundary element method （BEM）. As model problems we consider weakly singular and hypersingular integral equations of the first kind on a planar, open surface. We show that the Galerkin solutions （computed with the hp-version on geometric meshes） converge exponentially fast towards the exact solutions of the integral equations. An hp-adaptive algorithm is given and the implementation of the hp-version BEM is discussed together with the choice of efficient preconditioners for the ill-conditioned boundary element stiffness matrices. We also comment on the use of the hp-version BEM for solving Signorini contact problems in linear elasticity where the contact conditions are enforced only on the discrete set of Gauss-Lobatto points. Numerical results are presented which underline the theoretical results.

关键词： hp-version of the boundary element method Adaptive refinement Preconditioning Signorini contact

From foredeep to orogenic wedge-top: The Cretaceous Songliao retroforeland basin, China

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Geoscience Frontiers 2023年第3期14卷 65-73页

作者： Zhiqiang Feng stephan A.Graham Petroleum Exploration and Production Research Institute SINOPECNo.197 Baisha Rd.Beijing 112206China Department of Geological Sciences Stanford UniversityStanfordCA 94305USA

Songliao Basin,the largest Mesozoic intracontinental nonmarine basin in eastern China,initiated during the latest Jurassic as a backarc extensional basin;rifting failed and thermal cooling controlled subsidence through the early Late *** 2-D and 3D reflection seismic and borehole data with regional geological studies,we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma(marked by the T11 unconformity in the basin),including(1)significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin;(2)a shift of detrital provenance in the basin from north to southeast;and(3)propagation of E-W shortened structures,increasing eastward in amplitude,frequency,and degree of inversion toward the *** latest Cretaceous,foreland basin fill progressively deformed,as the foredeep evolved to a wedge-top tectonic setting,marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 *** of the basin was brought into the orogenic wedge and eroded by the end of the *** Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the *** normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin,whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the *** foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma.

关键词： Retroforeland basin Intracontinental basin Seismic reflection and borehole data Lithospheric plate dynamics Songliao basin

Emergence of instability-driven domains in soft stratified materials

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npj Computational Materials 2022年第1期8卷 931-936页

作者： Jian Li Viacheslav Slesarenko stephan Rudykh Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangshaHunan410075China Joint International Research Laboratory of Key Technology for Rail Traffic Safety Central South UniversityChangsha410075China National&Local Joint Engineering Research Center of Safety Technology for Rail Traffic Vehicle Central South UniversityChangsha410075China Cluster of Excellence livMatS@FIT–Freiburg Center for Interactive Materials and Bioinspired Technologies University of FreiburgGeorges-Köhler-Allee 105D-79110FreiburgGermany Department of Mechanical Engineering University of Wisconsin—MadisonMadisonWI53706USA School of Mathematical&Statistical Sciences National University of Ireland GalwayUniversity RoadGalwayIreland

Nature frequently employs the buckling phenomenon to facilitate the formation of complicated patterns across *** knowledge,however,is limited to a small set of buckling-induced microstructure transformations in soft composites;and the pattern formation phenomenon remains largely unknown for a vast pool of material ***,we investigate the unexplored rich domain of soft heterogeneous *** experimentally observe the formation of instability-driven domains in stratified composites with a non-dilute stiff *** illustrate that the discovered domain patterns are energetically favorable over ***,we introduce a closed-form analytical expression allowing us to predict the evolution of the patterns in the post-buckling ***,we show that various patterns can be pre-designed via altering material *** findings can help advance our understanding of the mechanisms governing pattern formations in soft biological tissues,and potentially enable the platform for mechanical metamaterials.

关键词： composites buckling stratified

Visualizing mitochondrial dynamics at the nanoscale

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Light(Science & Applications) 2024年第11期13卷 2421-2423页

作者： Till stephan Peter Ilgen Stefan Jakobs Buchmann Institute for Molecular Life Sciences Goethe University Frankfurt am MainFrankfurt am Main 60438Germany Department of NanoBiophotonics Max Planck Institute for Multidisciplinary Sciences37077 GöttingenGermany Clinic of Neurology University Medical Center GöttingenGöttingen 37075Germany Fraunhofer Institute for Translational Medicine and Pharmacology Translational Neuroinflammation and Automated MicroscopyGöttingen 37075Germany

The study of mitochondria is a formidable challenge for super-resolution microscopy due to their dynamic nature and complex membrane *** this issue,Ren et *** HBmito Crimson,a fluorogenic and photostable mitochondrial probe for STED microscopy and investigate how mitochondrial dynamics influence the spatial organization of mitochondrial DNA.

关键词： dynamics Visual dynamic

Euler-Lagrange/DEM simulation of wood gasification in a bubbling fluidized bed reactor

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Particuology 2009年第4期7卷 307-316页

作者： Michael Oevermann stephan Gerber Frank Behrendt Berlin Institute of Technology School of Process Sciences and EngineeringDepartment of Energy Engineering Fasanenstr.8910623 BerlinGermany

We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.

关键词： Euler-Lagrange simulation Discrete element method (DEM) Dense fluidized bed Biomass gasification

Influence of drag laws on pressure and bed material recirculation rate in a cold flow model of an 8 MW dual fluidized bed system by means of CPFD

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Particuology 2018年第1期16卷 70-81页

作者： stephan Kraft Friedrich Kirnbauer Hermann Hofbauer Bioenergy 2020+ GmbH Wiener Strasse 49 A- 7540 Gussing Austria TU Wien Institute of Chemical Engineering Getreidemarkt 9/166 Vienna Austria

A cold flow model of an 8 MW dual fluidized bed （DFB） system is simulated using the commercial compu- tational particle fluid dynamics （CPFD） software package Barracuda. The DFB system comprises a bubbling bed connected to a fast fluidized bed with the bed material circulating between them. As the hydrodynam- ics in hot DFB plants are complex because of high temperatures and many chemical reaction processes, cold flow models are used. Performing numerical simulations of cold flows enables a focus on the hydro- dynamics as the chemistry and heat and mass transfer processes can be put aside. The drag law has a major influence on the hydrodynamics, and therefore its influence on pressure, particle distribution, and bed material recirculation rate is calculated using Barracuda and its results are compared with experimental results. The drag laws used were energy-minimization multiscale （EMMS）, Ganser, Turton-Levenspiel, and a combination of Wen-Yu]Ergun. Eleven operating points were chosen for that study and each was calculated with the aforementioned drag laws. The EMMS drag law best predicted the pressure and dis- tribution of the bed material in the different parts of the DFB system. For predicting the bed material recirculation rate, the Ganser drag law showed the best results. However, the drag laws often were not able to predict the experimentally found trends of the bed material recirculation rate. Indeed, the drag law significantly influences the hydrodynamic outcomes in a DFB system and must be chosen carefully to obtain meaningful simulation results. More research may enable recommendations as to which drag law is useful in simulations ofa DFB system with CPFD.

关键词： Cold flow modeling Fluidization Computational particle fluid dynamics(CPFD) simulation Dual fluidized bed Computational fluid dynamics

Beautiful Thinking： Poetic Episteme in European Modernism

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中国比较文学 2017年第1期 20-28页

作者： stephan Kammer stephan Kammer is professor of Modem German Literatureat Ludwig-Maximilian University of Munich (LMU)

Poetic texts and poetological programs around 1900 claim a mode of thinking that exceeds the limits of rationality—beautiful thinking shallimply better thinking. In its most sophisticated utterances, poetry of Classical Modernism pretends to give better insights into the appearances and structures of the w orld than any other mode of know ***,it asserts a genuine aesthetic nomothesis. The paper sketches the tensions of claim and consequences with respect to some core positions of Classical Modernism( Hofmannsthal,Meyer-Graefe,Rilke).

关键词：诗典型的现代式美丽的思考美学理论

HIAWSC: An Immune Algorithm Based Heuristic Web Service Composition Framework

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Chinese Journal of Electronics 2014年第3期23卷 579-585页

作者： XU Jiuyun stephan Reiff-Marganiec School of Computer and Communication Engineering China University of Petroleum Network and Switch Technology Key Laboratory Beijing University of Posts and Telecommunication Department of Computer Science University of Leicester

The introduction of of web services has led to web service composition being a focus of many researchers. Composing web services using workflows is seen as the most realistic method from an industrial viewpoint. Amongst other method, the use of natural computing methods has been proposed previously to automate web service composition. The need for a fast response when computing the most suitable sequence of services is addressed in this paper. In particular, we propose a novel heuristic immune algorithm with an efficient encoding and mutation method. The algorithm involves two steps: an immune selection operation, which is maintaining antibody population diversity and the clonal selection. The use of a vaccine during the evolution provides heuristic information that accelerates the convergence. Our experimental results illustrate that the proposed heuristic immune algorithm is very effective in improving the convergence *** also provide a schema analysis for this method.

关键词： Web services composition Immune algorithm Heuristic information Schema analysis