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Supervision of two fundamental problems in modern fluid dynamics for sparing energy

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Journal of thermal Science 2009年第2期18卷 97-98页

作者： Jürgen Zierep Institut für Strmungslehre Universitt Karlsruhe

the normal shock at a curved surface in transonic flow leads to a superdetermined boundary value problem. A bump behind the shock decreases the drag of the airfoil and reduces the necessary energy. Flows of non-Newtonian media lead in the contrary to subdetermined boundary initial problems. the energy balance for these fluids is of great interest for chemical engineering.

关键词： transonic flow Shock at a curved wall Superdetermined problem Non- Newtonian media Subdeermined problem Energy balance.

Selective Suspension in Aqueous Sodium Dodecyl Sulfate According to Electronic Structure type Allows Simple Separation of Metallic from Semiconducting Single-Walled Carbon Nanotubes

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Nano Research 2009年第8期2卷 599-606页

作者： Kai Moshammer Frank Hennrich Manfred M.Kappes Forschungszentrum karlsruhe Institut für NanotechnologieD-76021 KarlsruheGermany Institut für Physikalische Chemie Universität KarlsruheD-76128 KarlsruheGermany

Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNts)when using aqueous sodium dodecyl sulphate(SDS)*** show here that both methods rely on an initial dispersion-by-sonication step,which is already selective with respect to electronic structure *** corresponding aqueous SDS“starting”suspensions obtained after sonication and purifi cation by simple centrifugation(70,000 g,1 h)contain semiconducting SWNts primarily in the form of small bundles whereas metallic SWNts are predominantly suspended as individual *** gradient centrifugation then separates the bundles from the individual tubes on the basis of differences in their overall buoyant *** electrophoresis separates the longer bundles from the shorter individual tubes on the basis of their different *** also demonstrate that such starting suspensions can be fractionated according to electronic structure type by even simpler techniques such as size exclusion chromatography or gel fi ltration,thus opening the way for simple scale-up.

关键词： Single-walled carbon nanotubes metallic–semiconducting separation electrophoresis density gradient centrifugation size exclusion chromatography

Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy

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Nano Research 2008年第4期1卷 321-332页

作者： Aravind Vijayaraghavan Sabine Blatt Christoph Marquardt Simone Dehm Raghav Wahi Frank Hennrich Ralph Krupke Institut für Nanotechnologie Forschungszentrum KarlsruheD-76344 Eggenstein-LeopoldshafenGermany Physikalisches Institut Universität KarlsruheD-76021 KarlsruheGermany

We introduce voltage-contrast scanning electron microscopy(VC-SEM)for visual characterization of the electronic properties of single-walled carbon ***-SEM involves tuning the electronic band structure and imaging the potential profi le along the length of the *** resultant secondary electron contrast allows to distinguish between metallic and semiconducting carbon nanotubes and to follow the switching of semiconducting nanotube devices,as confi rmed by in situ electrical transport *** demonstrate that high-density arrays of individual nanotube devices can be rapidly and simultaneously characterized.A leakage current model in combination with fi nite element simulations of the device electrostatics is presented in order to explain the observed contrast evolution of the nanotube and surface *** work serves to fi ll a void in electronic characterization of molecular device architectures.

关键词： Carbon nanotubes electronic properties voltage-contrast scanning electron microscopy electrostatics

BIFURCAtION OF PERIODIC SOLUtION IN A tHREE-UNIt NEURAL NEtWORK WItH DELAY

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Acta Mathematicae Applicatae Sinica 2001年第3期17卷 375-381页

作者：林怡平 Department of Mathematics Kunming University of Science and Technology Kunming China Mathematisches Institut I Universität Karlsruhe Karlsruhe Germany

A system of three-unit networks with no self-connection is investigated, the general formula for bifurcation direction of Hopf bifurcation is calculated, and the estimaion formula of the period for periodic solution i... 详细信息

关键词： Hopf bifurcation bifurcation direction three-unit network system

Principles of carbon nanotube dielectrophoresis

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Nano Research 2021年第7期14卷 2188-2206页

作者： Wenshan Li Frank Hennrich Benjamin S.Flavel Simone Dehm Manfred Kappes Ralph Krupke Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe 76021Germany Institute of Physical Chemistry Karlsruhe Institute of TechnologyKarlsruhe 76021Germany Institute of Materials Science Technische Universität DarmstadtDarmstadt 64287Germany Institute for Quantum Materials and technologies Karlsruhe Institute of TechnologyKarlsruhe 76021Germany School of Mechanical Engineering Shanghai Jiao Tong UniversityNo.800 Dongchuan RoadShanghai 200240Chin

Dielectrophoresis(DEP)describes the motion of suspended objects when exposed to an inhomogeneous electric *** has been successful as a method for parallel and site-selective assembling of nanotubes from a dispersion into a sophisticated device *** have conducted extensive works to understand the DEP of nanotubes in aqueous ionic surfactant ***,only recently,DEP was applied to polymer-wrapped single-walled carbon nanotubes(SWCNts)in organic solvents due to the availability of ultra-pure SWCNt *** this paper,the focus is on the difference between the DEP in aqueous and organic *** starts with an introduction into the DEP of carbon nanotubes(CNt-DEP)to provide a comprehensive,in-depth theoretical background before discussing in detail the experimental procedures and *** academic interests,this work focuses on the CNt-DEP deposition scheme,discusses the importance of the electrical double layer,and employs finite element simulations to optimize CNt-DEP deposition condition with respect to the experimental *** important outcome is an understanding of why DEP in organic solvents allows for the deposition and alignment of SWCNts in low-frequency and even static electric fields,and why the response of semiconducting SWCNts(s-SWCNts)is strongly enhanced in non-conducting,weakly polarizable *** to further improve CNt-DEP for s-SWCNt-relevant applications are given as ***,this work should serve as a practical guideline to select the appropriate setting for effective CNt DEPs.

关键词： single-walled carbon nanotubes hydrodynamics assembly deposition alignment polarizability dielectrophoresis

A new hybrid piezoelectric ultrasonic motor with two stators

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Journal of Central South university of technology 2005年第3期12卷 324-328页

作者：易幼平 Wolfgang Seemann Rainer Gausmann 钟掘 College of Mechanical and Electrical Engineering Central South University Changsha 410083China Institut für technische Mechanik Universitt KarlsruheKarlsruhe 76128Germany AG Maschinendynamik Universitt Kaiserslautern Kaiserslautern 67653 Germany

A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. the results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. the speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.

关键词： piezoelectric ultrasonic motor lead zirconate titanate resonance frequency vibration

Dielectric-ion-conductive ZnNb2O6 layer enabling rapid desolvation and diffusion for dendrite-free Zn metal batteries

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Journal of Energy Chemistry 2025年第1期100卷 693-701页

作者： Haifeng Yang Jian Wang Panpan Zhang Xiaomin Cheng Qinghua Guan Jing Dong Bixian Chen Lujie Jia Jing Zhang Yongzheng Zhang Yunjian Liu Hongzhen Lin School of Materials Science and Engineering Jiangsu University i-Lab & CAS Key Laboratory of Nanophotonic Materials and Devices Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Helmholtz Institute Ulm (HIU) karlsruhe Institute of technology (KIt) School of Materials Science and Engineering Xi'an University of Technology State Key Laboratory of Chemical Engineering East China University of Science and Technology

Rechargeable aqueous zinc-metal batteries （AZMBs） are promising candidates for large-scale energy storage systems due to their low cost and high ***,their performance and sustainability are significantly hindered by the sluggish desolvation kinetics at the electrode/electrolyte interface and the corresponding hydrogen evolution reaction where active water molecules tightly participate in the Zn（H2O）62+solvation ***,learnt from self-generated solid electrolyte interphase （SEI） in anodes,the dielectric but ion-conductive zinc niobate nanoparticles artificial layer is constructed on metallic Zn surface （ZNB@Zn）,acting as a rapid desolvation *** zincophilic and dielectric-conductive properties of ZNB layer accelerate interfacial desolvation/diffusion and suppress surface corrosion or dendrite formation,achieving uniform Zn plating/stripping behavior,as confirmed by electronic/optical microscopies and interface spectroscopical measurements together with theoretical ***,the as-prepared ZNB@Zn electrode exhibits excellent cycling stability of over 2000 h and robust reversibility （99.54%） even under high current density and depth of discharge ***,the assembled ZNB@Zn-based full cell displays high capacity-retention rate of 80.21%after 3000 cycles at 5 A g-1and outstanding rate performance up to 10 A *** large-areal pouch cell is stabilized for hundreds of cycles,highlighting the bright prospects of the dielectric but ion-conductive layer in further application of AZMBs.

关键词： Zn metal battery Dielectric artificial layer Rapid ion diffusion Zincophilic diffusion Active water inhibition

Numerical Noise Prediction in Fluid Machinery

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Journal of thermal Science 2005年第3期14卷 230-235,248页

作者： Iris PANtLE Franco MAGAGNAtO Martin GABI Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. the configurations of the calculations comply with an existing experimental setup chosen for evaluation. the used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. the difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation

从煤焦油软沥青和苯基硅烷制备硅取代聚芳烃中间相的研究(英文)

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新型炭材料 2003年第2期18卷 1-9页

作者： J. Schwendinger W.G. Zhang K.J. Hüttinger Institut für Chemische technik Universitt KarlsruheInstitut für Chemische Technik Universitt KarlsruheInstitut für Chemische Technik Universitt Karlsruhe Kaiserstr. 12 76128 Karlsruhe Germany Kaiserstr. 12 76128 Karlsruhe Germany Kaiserstr. 12 76128 Karlsruhe Germany

　过滤后的煤焦油沥青分别与一,二,三,四苯基硅烷在1MPa氩气气氛和420℃～460℃温度下共炭化,合成了硅取代聚芳烃中间相。在四种合成中间相中,元素硅的起始加入量均为2%。测定了裂解残留物和硅的收率、可溶性、玻璃转化温度以及裂解残... 详细信息

　过滤后的煤焦油沥青分别与一,二,三,四苯基硅烷在1MPa氩气气氛和420℃～460℃温度下共炭化,合成了硅取代聚芳烃中间相。在四种合成中间相中,元素硅的起始加入量均为2%。测定了裂解残留物和硅的收率、可溶性、玻璃转化温度以及裂解残留物的炭收率;并分别以偏光显微镜和电子探针微分析法考察了残留物的微结构和相应的硅分布,硅的收率取决于不同的苯取代硅烷的挥发性和反应性。裂解残留物显示出三种不同的共存相:(a)含有粗镶嵌织构和痕量硅的光学各向异性相;(b)硅含量较高的光学各向同性相;(c)含细镶嵌织构和中等硅含量的光学各向异性相。最后这种中间相主要来自二,三苯取代硅烷与煤沥青的共炭化,是由于硅取代聚芳烃中碳原子并破坏了其分子的平面结构而引起的。

关键词：煤焦油软沥青苯基硅烷制备硅聚芳烃中间相取代研究热解微结构煤焦油沥青

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