Papers by Keyword: Magnetic Field

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Authors: Yousef Razouk, Eric Duhayon, Bertrand Nogarede
Abstract: This paper deals with the development of a new type of composites called "magnetoactivated" polymers and the exploration of some of their potential applications. "Magnetoactivated" polymers consist of small embedding (micron-sized) magnetic particles in a high elastic silicon matrix to render it magnetically active and at the same time mechanically strong. The experimental characterizations obtained (magnetic permeability and Young modulus) were systematically compared with the values resulting from the modeling of this material.The elastic properties of our "magnetoactivated" silicon motive us to use them as pump membranes, the evolution of the displacement of the pump membrane with the applied magnetic field were verified in ANSYS and experimentally for various contents of iron particles in the silicon matrix.
Authors: Henri Nguyen-Thi, Jiang Wang, Georges Salloum-Abou-Jaoude, Guillaume Reinhart, Imants Kaldre, Nathalie Mangelinck, Zhong Ming Ren, Leonids Buligins, Andris Bojarevics, Yves Fautrelle, Olga Budenkova, Tamzin Lafford
Abstract: It is well known that the application of a magnetic field during the growth process can have pronounced effects on cast material structures and their properties, so that magnetic fields have been widely applied since the 1950s. In the case of a permanent magnetic field, some recent results revealed a dual effect on the liquid metal flow. 1: the magnetic field has a selective damping action on the flow at the scale of the crucible, due to the Lorentz force; 2: the interaction of thermo-electro-magnetic (TEM) currents in the close vicinity of the solid-liquid interface with the applied magnetic field leads to the generation of electromagnetic forces, which act both on the liquid and on the solid at the scale of the microstructure. We present an experimental investigation of the TEM forces induced by a permanent magnetic field during columnar and equiaxed solidification of Al-4wt%Cu. In situ visualization was carried out by means of synchrotron X-ray radiography, which is a method of choice for studying dynamic phenomena. It was shown that the TEM forces were at the origin of a motion of dendritic particles, perpendicular to the direction of gravity. A heuristic analysis allowed us to estimate the fluid velocities and the velocities of the solid particles, and a good agreement was achieved with the experimental data. Similar observations were also made during equiaxed growth in a temperature gradient. The in situ observation of the grain trajectories for various values of the temperature gradient demonstrated that gravity and TEM forces were the driving forces which controlled the grain motion.
Authors: Dan Jiang, Ping Yang, Kun Jiang
Abstract: As a type of solid state switch, MR (magnetoresistive) sensor detects the air cylinder piston’s position in pneumatic control system. The construction and working principle of the air cylinder with MR sensor are introduced. Using 2-D magnetic field finite element analysis (FEA) method, the magnetic field distribution of air cylinder with piston motion is analyzed. Simulation results are given. The magnetic flux density characteristics are compared between piston wear or not.
Authors: Ji Jue Wei, Sen Kai Lu
Abstract: The magnetic fields in the 320 kA Al reduction cells have been calculated using ANSYS. The calculated results show that the magnetic field lines are concentrated in the cell wall; the magnetic fields in the Al reduction cell form a clockwise swirl along the Z-axis; the magnetic field strengthen in the corners; the vertical magnetic field value of the Al reduction cell is slightly higher. The range of BX, BY and BZ is -0.048~0.145 T, -0.046~0.292 T and -0.183~0.196 T in the Al of the Al reduction cell, respectively. The range of BX, BY and BZ is -0.183~0.348 T, -0.447~0.515 T and -0.350~0.225 T in the electrolyte of the Al reduction cell, respectively. The range of BX, BY and BZ is -0.020~0.035 T, -0.014~0.016 T and -0.015~0.028 T on the interface of melt of the Al reduction cell, respectively. The optimization design of the Al reduction cells should give full consideration to the influence of the ferromagnetic material
Authors: Ivan Yatchev, Krastyo Hinov, Vultchan Gueorgiev
Abstract: Three-dimensional finite element method has been used for modelling of the magnetic field and computation of the electromagnetic force of recently developed permanent magnet linear actuator. The actuator is subject to specific requirements – having four stable positions without supply and maintaining minimum static force during the whole working stroke. The actuator consists of several cores with coils placed on a common yoke and a moving permanent magnet. It is intended for needle driving in a knitting machine. Influence of different factors on the static force characteristic is estimated.
Authors: Yan Xu, Jun Xu, Wei Hua Zhu, Xia Feng, Hai Yan Xie
Abstract: The tidal motion of the ocean water through the ambient magnetic field, generates secondary electric and magnetic field. The magnetic fields generated by the diurnal (O1) ocean flow can be clearly detected. We simulate the magnetic signals for tidal constituents –diurnal (O1) tides. The idea of exploiting tidal signals for EM studies of the Earth is not new, but so far it was used only for interpretation of inland and transoceanic magnetic field data due to O1. Emphasis in this work is made on a discussion of sea bottom electric field of the same origin.
Authors: Z.J. Cai, Li Jiang Zeng
Abstract: It is important to track a free flying insect to investigate its flight performance. Conventional video tracking systems are difficult to track a highly maneuverable insect, because the capture frequency of the camera is limited and it can hardly get the position of the insect in real time. We proposed a fast sensing method for insect tracking based on magnetic search coil sensors. It can simultaneously determine the orientation and position of the sensors. We constructed a system, calibrated the magnetic device. We developed a set of calculating methods and measured several positions and angles of coil sensors. The results show that it can rapidly provide the tracking feedback information to meet the requirement for insect tracking.
Authors: Sadahiro Tsurekawa, Tadao Watanabe
Authors: J. Jiang, Yong Bo Wu, Xu Yue Wang, M. Kato
Abstract: This paper presents a new magnetic polishing liquid (MPL) produced by mixing sub-micron or micron order abrasive particles into a magnetic compound fluid (MCF) and its fundamental performance in surface finishing. MCF is an intelligent fluid, which is developed by mixing a magnetic fluid (MF) and a Magneto-rheological fluid (MRF) into a solvent, and hence reacting upon magnetic fields. In the present work, seven kinds of kerosene-based MPLs were prepared. The hydrodynamic characteristics of MPLs such as the viscosities under different magnetic fields were investigated. The obtained result indicated that the viscosity increases with the growing of the magnetic field and that the type of MPL affects greatly the viscosity. This phenomenon was discussed by observing the magnetic clusters formed in MPL. It was observed that the magnetic clusters are distributed along the magnetic fluxes. An experimental result indicated that the surface roughness varies with polishing time and gets smallest at a certain value of magnetic field strength.
Authors: Yong Jiang Niu, Li Min Shi, Er Liang Liu
Abstract: A new polishing head is studied in magnetic-electrochemical compound polishing in the paper. Added a magnetic field whose direction is parrallel to the electrical field’s directions, the charged partcles between two electrodes can move in spirals in magnetic-electrochemical compound polishing, and then the condition of chemical reaction is improved. If the direction of magnetic field is changed alternative, the effect of polishing can be improved more clearly. The tool can be fixed on spindle of CNC easily. The tool is flexible, so it can make the polishing head and workpiece touch evenly each other. Because the head of magnetic-electrochemical compoud polishing tool is a series, the head can be replaced conveniently according to different surface. Particularly,the tool can change strength of the magnetic field easily. At last, the tool is tested and its function is perfect.
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