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北京城市交通发展政策述评及对拥挤收费的讨论

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城市交通 2011年第4期9卷 1-10页

作者： Felix Creutzig maximilian thess 周江评 Michael Replogle 韩慧敏耿雪张绍滨柏林工业大学气候变化经济学系德国柏林10623 宇恒可持续交通研究中心北京100004 交通与发展政策研究所美国华盛顿20036 中国城市规划设计研究院北京100037 双鸭山市城市建设档案馆黑龙江双鸭山155100

中国城市交通发展政策承载了很多共同利益,包括减少空气污染与交通拥堵、提高骑车者与行人的交通安全以及改善公共汽车服务的可靠性。逐一评述北京市为达成上述事项而实施的包括公共交通、限行措施、小汽车数量调控和停车管理在内的一... 详细信息

中国城市交通发展政策承载了很多共同利益,包括减少空气污染与交通拥堵、提高骑车者与行人的交通安全以及改善公共汽车服务的可靠性。逐一评述北京市为达成上述事项而实施的包括公共交通、限行措施、小汽车数量调控和停车管理在内的一系列城市交通发展政策。指出北京市已实施的一系列政策还无法实现缓解交通拥堵的目标,未来可以考虑采取更加行之有效的措施,如交通拥挤收费。由此定量论证了北京市实施拥挤收费的前景及其综合效益,并探讨了实施拥挤收费的重要保障因素:决策与公平、综合配套措施、政府支持、国际经验。

关键词：城市交通交通发展政策拥挤收费

Influence of velocity profile on calibration function of Lorentz force flowmeter

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Applied Mathematics and Mechanics(English Edition) 2014年第8期35卷 993-1004页

作者： C.STELIAN 于洋李本文 A.thess Institute of Thermodynamics and Fluid Mechanics Ilmenau University of TechnologyIlmenau 98684Germany Department of Physics West University of TimisoaraTimisoara 300233Romania Key Laboratory of Electromagnetic Processing of Materials Northeastern University Institute of Engineering Thermodynamics German Aerospace CenterStuttgart 70569Germany

A Lorentz force flowmeter is a noncontact electromagnetic flow-measuring device based on exposing a flowing electrically conducting liquid to a magnetic field and measuring the force acting on the magnet system. The measured Lorentz force is proportional to the flow rate via a calibration coefficient which depends on the velocity distribution and magnetic field in liquid. In this paper, the influence of different velocity profiles on the calibration coefficient is investigated by using numerical simulations. The Lorentz forces are computed for laminar flows in closed and open rectangular channels, and the results are compared with the simplified case of a solid conductor moving at a constant velocity. The numerical computations demonstrate that calibration coefficients for solid bodies are always higher than for liquid metals. Moreover, it can be found that for some parameters the solid-body calibration coefficient is almost twice as high as for a liquid metal. These differences are explained by analyzing the patterns of the induced eddy currents and the spatial distributions of the Lorentz force density. The result provides a first step for evaluating the influence of the laminar velocity profiles on the calibration function of a Lorentz force flowmeter.

关键词： laminar flow numerical simulation electromagnetic velocimetry

Theoretical and Numerical Stability Analysis of the Liquid Metal Pinch Using the Shallow Water Approximation

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Journal of Thermal Science 2008年第3期17卷 261-266页

作者： E. Zienicke Ben-Wen Li A. thess A. Krazschmar P. Terhoeven Institut fur Physik Technische Universitat Ilmenau PF 100565 D-98684 Ilmenau Germany Key Laboratory of National Education Ministry for Electromagnatic Processing of Materials POB 314 NortheasternUniversity Shenyang 110004 China Fakultat Maschinenbau Technische Universitat Ilmenau PF 100565 D-98684 Ilmenau Germany Moeller GmbH Hein Moeller Str. 7-11 D-53115 Bonn Germany

The pinch instability for a cylindrical jet of liquid metal passed through by an axial electrical current is investigated. Besides the pinch effect originating from surface tension, the Lorentz force, created by the axial current density and the corresponding azimuthal magnetic field, causes an electromagnetic pinch effect. This effect has drawn attention in electrical engineering, because it can be used in the construction of liquid metal current limit- ers with self-healing properties. In this paper a simple model is derived using the shallow water approximation： the equations describing the full system are reduced to two one-dimensional evolution equations for the axial velocity and the radius of the jet. A stability analysis for this reduced system is carried out yielding critical current density and the growth rate for the instability. To investigate the nonlinear behaviour of the pinch instability for finite perturbations simulations, the shallow water model are performed.

关键词： MHD pinch instability analysis electric current limiter numerical simulation Fourier spectralmethod

Experimental Study and Numerical Visualization of Physical Fields of Electromagnetic Pumps Constructed on Permanent Magnets

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Journal of Iron and Steel Research International 2012年第S2期19卷 621-624页

作者： KOLESNIKOV Yurii WANG Xiaodong thess André Institute Thermo and Fluid Mechanics Ilmenau University of Technology Graduate University of Chinese Academy of Sciences College of Materials Science and Opto-Electronic Technology

Pumps with magnet systems constructed on permanent magnets and performed in two manners like two-disk type and the cylindrical rotor type are ***,by way of example we consider the experimental study of disk pump with straight channel;second,we analyse the results of numerical simulation of cylindrical pump in two cases,namely,of straight and U-bend forms of pump *** a high speed of pump rotation when induced magnetic field becomes essential in as against the applied field,*** the skin-effect takes place,the pump characteristics are *** of physical fields of the pumps is reported.

关键词： electromagnetic pump magnetic field distribution Lorentz force eddy current pressure flow rate

Investigation of Lorentz Force Velocimetry Using Electromagnets

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Journal of Iron and Steel Research International 2012年第S1期19卷 106-109页

作者： SANTARA Fatoumata Bintou KARCHER Christian thess Andre Institute of Thermodynamics and Fluid Mechanics Ilmenau University of TechnologyIlmenau 100565 98684Germany

The present work is an analysis on the ElectroMagnetic Lorentz Force Velocimetry(EM-LFV).This noncontact flow measurement technique is based on evaluating the Lorentz force generated by the interactions of an electrically conducting fluid with a localized magnetic field that is produced by *** and numerical calculations were carried out as a continuation of a previous work published by thess et *** objective is to establish the behavior of the Lorentz force as a function of the main geometric parameters considered in the studied geometry. Thus we present here the evolution of the Lorentz force induced in a translating cylindrical solid body and the coefficient of sensitivity of the flowmeter thanks to numerical simulations in respect with the main geometrical parameters of the problem.

关键词： computational magneto-hydrodynamics Lorentz force velocimetry electromagnet

Lorentz Force Sigmometry

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Journal of Iron and Steel Research International 2012年第S1期19卷 123-126页

作者： Mladen Zec Robert P.Uhlig Marek Ziolkowski Hartmut Brauer Andre thess Department of Advanced Electromagnetics Ilmenau University of TechnologyIlmenau 100565 98684 Germany Institute of Thermodynamics and Fluid Mechanics llmenau University of TechnologyIlmenau 100565 98684Germany

The present communication reports a new technique for the contactless measurement of the specific electrical conductivity of a solid conductor or an electrically conducting *** term the technique 'Lorentz Force Sigmometry' where the neologism 'Sigmometry' is derived fiom the Greek letter sigma,often used to denote the electrical *** force sigmometry(abbreviated LoFoS)is based on similar principles as the traditional eddy current testing but allows a larger penetration depth and is less sensitive to variations in the distance between the sensor and the *** we formulate the theory of LoFoS and numerically compute the calibration function which is necessary for determining the unknown electrical conductivity from the measurement of a Lorentz force.

关键词： electrical conductivity Lorentz force finite element method

Development of a Non-Contact Electromagnetic Surface Velocity Sensor for Molten Metal Flow

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Journal of Iron and Steel Research International 2012年第S1期19卷 509-513页

作者： JIAN Dan-dan KARCHER Christian XU Xiu-jie DENG An-yuan WANG En-gang thess André Ilmenau University of Technology Institute of Thermodynamics and Fluid MechanicsIlmenau 100565Germany Key Laboratories on EPM Ministry of ScienceNortheastern University

During continuous casting of steel,knowledge of both direction and magnitude of the velocity at the mold surface is of special ***,the surface is covered by a non-transparent layer of mold powder to prevent formation of ***,this meniscus flow cannot be registered by optical measurement ***-contact measurement methods are of *** of such non-invasive techniques is Lorentz force veloeimetry(LFV).It is based on measuring the electromagnetically induced force acting on a magnet *** this paper we present a series of experiments that aim to demonstrate the feasibility of using two identical velocimeters,termed Time-of-Flight LFV(ToF LFV).Using ToF LFV the free-surface velocity may be purely determined by cross-correlating the two force signals delivered by the two force *** have developed a special prototype of such a measuring device termed meniscus velocity sensor(MVS).It has been designed to record local surface velocities in high-temperature metal *** Ilmenau University of Technology,the method has been successfully tested using both solid body movement and Ga^(68%)In^(20%)Sn^(12%)as a low-melting model *** the present paper we apply this technique to the case of high-temperature metal *** more detail,we present test measurements under industry-relevant conditions using both Sn^(32%)pb^(52%)Bi at 210℃ and molten steel at about 1700℃.These experiments were conducted at Key Laboratories on EPM at North Eastern *** evaluation of the data shows that our prototype of MVS works well in producing reproducible signals of which surface velocity can be determined.

关键词： free-surface liquid melt flow Lorentz force velocimetry magnetohydrodynamics

Lorentz Force Velocimetry for Poorly Conducting Fluids-Development and Validation of a Novel Flow Rate Measurement Device

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Journal of Iron and Steel Research International 2012年第S2期19卷 613-616页

作者： WEGFRASS Andre RESAGK Christian DIETHOLD Christian FRHLICH Thomas WERNER Michael HALBEDEL Bernd thess Andre Institute of Thermodynamics and Fluid Mechanics Department of Mechanical EngineeringIlmenau University of Technology Institute of Process Measurement and Sensor Technology Department of Mechanical EngineeringIlmenau University of Technology Institute of Inorganic-nonmetallic Materials Department of Mechanical EngineeringIlmenau University of Technology

The paper demonstrated the feasibility of Lorentz Force Velocimetry for flow rate measurements of weakly conducting electrolytes using experimental results on salt water flow exposed to a permanent magnet *** innovative flow measurement technique allows the non-contact determination of flow rates and relies on the interaction between a magnetic field and a moving conducting *** an electrically conducting fluid moves through the magnetic field a Lorentz force is generated and acts on the measurement *** present report provides an overview about the experimental setups and the first measurement results.

关键词： Lorentz force velocimetry flow measurement electrolytes non-contact measurement

Lorentz Force Velocimetry for Local Velocity Measurement

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Journal of Iron and Steel Research International 2012年第S1期19卷 578-581页

作者： HEINICKE Christiane PULUGUNDLA Gautam TYMPEL Saskia BOECK Thomas KARCHER Christian SCHUMACHER Joerg RAHNEBERG Ilko FROEHLICH Thomas HILBRUNNER Falko thess André Department of Mechanical Engineering Ilmenau University of TechnologyIlmenau 98684Germany

Standard flow measurement techniques fail for liquid metals due to their high temperatures,opaqueness and ***,recent developments in the measurement of volumetric fluxes of industrially relevant metal melts have been *** of these methods,Lorentz Force Velocimetry(LFV)is based on the measurement of Lorentz forces generated when an electrically conducting fluid moves through a magnetic *** aim is to extend the working range of this method to the measurement of local flow *** resolve local velocity fluctuations we reduce the size of the permanent magnet that produces the magnetic *** use the fundamental setup of a square duct filled with the eutectic alloy GaInSn and having a cross-section of 5 cm by 5 *** magnet cube employed has an edge length of 1 *** this setup,we investigate both experimentally and numerically the interaction between the liquid metal flow and the non-uniform magnetic *** results help in understanding the effect of flow dynamics on the total Lorentz force.

关键词： liquid metal flow measurement local resolution contactless