Journal articles on the topic 'Constant speed of rotating magnetic field'
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Hung, Sheng Lun, and Jik Chang Leong. "Effects of Regional Magnetic Field on Rotating MHD Flow Field of Unity Magnetic Prandtl Number." Journal of Applied Mathematics 2012 (2012): 1–17. http://dx.doi.org/10.1155/2012/804105.
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This work numerically studies the flow pattern of a magnetic fluid filled within an annulus whose inner cylinder is moving at a constant rotational speed, while the outer cylinder is stationary but under the influence of a nonuniform external magnetic field. The magnetic field consists of four basic configurations, that is, completely circular, semicircular, quarter circular, and alternately quarter circular. The strength of the external magnetic field is characterized using a reference Hartmann number. As the reference Hartmann number increases, the fluid elements need to overcome greater resistance to enter the region with magnetic field. Hence, there always exists an apparent recirculation cell within the region without externally applied magnetic field. The strength and size of the recirculation cell depend on the reference Hartmann number, the number and size of the discrete regions without external magnetic field. Only the shear stress on the moving cylinder always increases in magnitude with the reference Hartmann number and the span of the single external magnetic field region. Splitting and separating the external magnetic field may increase the magnitude of the shear stress on the moving inner cylinder but decrease that on the stationary outer cylinder. If the magnitude of the shear stress on the outer cylinder reduces beyond zero, a shear stress in the opposite sense will increase in magnitude with Hartmann number.
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Jacob, Angelo, and Nuno Monteiro. "A new concept of superelevation in magnetic levitation – prodynamic." Transportation Systems and Technology 4, no. 4 (December 19, 2018): 77–111. http://dx.doi.org/10.17816/transsyst20184477-111.
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Background: The topic of Magnetic Levitation systems, in terms of land mass transport, have created high expectations compared to aviation and also to the high speed railway industry. This new concept comes to revolutionize the terrestrial mass transport, in both the speeds and the subject of friction. Magnetic levitation solves the issue of attrition between material contact and as such may also be an opportunity to solve the question of constant physical superelevation.
Aim: Precisely that point of superelevation coupled with magnetic levitation, eliminating the rigid physical structures to laterally lift the vehicle in a curve. Current magnetic levitation systems do not address this issue of dynamic superelevation. It’s exposed an improvement technology which is a theoretical possibility of a track through a new magnetic line can apply necessary rotation to the vehicle in curve and adjust its rotation according to the speed that vehicle moves.
Methods: In order to make this system to work it is suggested the introduction of a magnetic field in the new line, which will allow the vehicle to rotate in curves and will negate the need of the conventional static superelevation.
This study appeared as a result of an investigation of a master's thesis in civil engineering at ISEP, where the participants created the concept of dynamic superelevation in the context of magnetic levitation. The project was applied to the reformulation of an existing railway network. The study base of this model resulted from a broad survey of current magnetic levitation systems. Then came the idea of creating a third dynamic magnetic field to operate the curved superelevation.
Results: The result of the study was the creation of a new "monorail" system of simple and geometrically constant structure. The new line has the advantage of providing a simple and constant geometry, facilitating the manufacture, assembly and thus making it much more economical compared to the current systems. The cross-section allows the vehicle to fit perfectly and with the creation of rotating magnetic fields, the vehicle can be turned to both sides, at the required inclination, according the speed. With this new concept called ProDynamic, the geometry design in plan is totally independent of the speed practiced by the vehicle, where it can travel in curve at different speeds, but with the same lateral no-compensated acceleration, without detriment of passenger comfort.
Conclusion: Combining existing systems with this new concept, it is possible to create a total freedom in curves and superelevation, which will provide a maximum comfort and significant construction savings. There is therefore no longer a problem of deficiency or excess cant, as currently exists on railways. The advantage in the ProDynamic system is that it is possible to greatly reduce or even eliminate the lateral no-compensated acceleration.
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Roychoudhuri, S. K., and Manidipa Banerjee (Chattopadhyay). "Magnetoelastic plane waves in rotating media in thermoelasticity of type II (G-N model)." International Journal of Mathematics and Mathematical Sciences 2004, no. 71 (2004): 3917–29. http://dx.doi.org/10.1155/s0161171204404566.
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A study is made of the propagation of time-harmonic plane waves in an infinite, conducting, thermoelastic solid permeated by a uniform primary external magnetic field when the entire medium is rotating with a uniform angular velocity. The thermoelasticity theory of type II (G-N model) (1993) is used to study the propagation of waves. A more general dispersion equation is derived to determine the effects of rotation, thermal parameters, characteristic of the medium, and the external magnetic field. If the primary magnetic field has a transverse component, it is observed that the longitudinal and transverse motions are linked together. For low frequency (χ≪1,χbeing the ratio of the wave frequency to some standard frequencyω∗), the rotation and the thermal field have no effect on the phase velocity to the first order ofχand then this corresponds to only one slow wave influenced by the electromagnetic field only. But to the second order ofχ, the phase velocity, attenuation coefficient, and the specific energy loss are affected by rotation and depend on the thermal parameterscT,cTbeing the nondimensional thermal wave speed of G-N theory, and the thermoelastic couplingεT, the electromagnetic parametersεH, and the transverse magnetic fieldRH. Also for large frequency, rotation and thermal field have no effect on the phase velocity, which is independent of primary magnetic field to the first order of (1/χ) (χ≫1), and the specific energy loss is a constant, independent of any field parameter. However, to the second order of (1/χ), rotation does exert influence on both the phase velocity and the attenuation factor, and the specific energy loss is affected by rotation and depends on the thermal parameterscTandεT, electromagnetic parameterεH, and the transverse magnetic fieldRH, whereas the specific energy loss is independent of any field parameters to the first order of (1/χ).
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Siddiqui, Abuzar Abid, and Ali J. Chamkha. "Thermo-magnetohydrodynamic effects on Cu + engine oil/water nanofluid flow in a porous media-filled annular region bounded by two rotating cylinders." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 12 (February 16, 2020): 2360–75. http://dx.doi.org/10.1177/0954406220906435.
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We examine the thermo-magnetohydrodynamic effects on nanofluid flow in a porous circular annular region bounded by two rotating cylinders in the presence of a constant radial magnetic field but variable thermal conductivity. The nanofluid consists of a sample liquid (water/ engine oil) along with suspended copper nanoparticles. This physical problem is formulated and analytical solutions for the governing equations are obtained by using the homotopy analysis method in the form of the physical variables such as, the pressure, fluid speed, temperature, shear stress, heat transfer, and the concentration of nanoparticles. The obtained results are compared with the existing results for the clear fluid and are found in excellent agreement. The effects of the field parameters on these physical variables are studied. It is found that the fluid speed (pressure) increases (decreases) with the Forchheirmer coefficient, porosity, applied magnetic field intensity, and the angular speed of the outer cylinder, but it decreases with the angular speed of the inner cylinder for both liquids. The reverse flow exists if the inner and outer cylinders are rotating in the opposite directions for both the liquids. Furthermore, the thermal transfer rate in the engine oil is lower than that in water. If the annulus region is squeezed, then the fluid speed decays while the pressure rises. The temperature and the thermal transfer rate decay if we march from the inner cylinder to the outer one. The porosity and the angular speed of the outer cylinder enhance the viscous dissipation and shear stress.
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Shih, Alexander H., and Steven Y. Liang. "Magnetic Levitation and Rotation for Feasibility of Free-Form Machining." Applied Mechanics and Materials 496-500 (January 2014): 1048–51. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.1048.
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This paper presents a new transformative manufacturing methodology for free-form machining. An experimental prototype machine is constructed to levitate and rotate an object attached with sharp edges, which act as a cutter for the purpose of performing machining processes. This device aims to lead to a technological breakthrough, overcoming the limitation of the workpiece features, and achieve greater free-form machining capability. The construction of curved holes and interior surfaces are constrained by the geometry of the machine tool. The proposed concept creates a new device that uses a magnetic field generator as a base. It is loaded with a constant power imposing a vertical physical force to balance gravity and stabilize the cutting tool. With the uniqueness of a preferred orientation between the tool and the base, a rotating surface placed below the base permits the rotation of the cutting tool in order to achieve desired tool rotation speed. A smooth and controlled cut is achieved on a soft material. The result shows the feasibility of the device to achieve similar outcomes as a machine tool.
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Selimefendigil, Fatih, and Ali J. Chamkha. "MHD mixed convection of nanofluid in a three-dimensional vented cavity with surface corrugation and inner rotating cylinder." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 4 (February 18, 2019): 1637–60. http://dx.doi.org/10.1108/hff-10-2018-0566.
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Purpose This study aims to numerically examine mixed convection of CuO-water nanofluid in a three-dimensional (3D) vented cavity with inlet and outlet ports under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticles, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above. Design/methodology/approach The bottom surface is corrugated with a rectangular wave shape, and the rotating cylinder surface and cavity bottom surface were kept at constant hot temperatures while the cold fluid enters the inlet port with uniform velocity. The complicated interaction between the forced convection and buoyancy-driven convection coupled with corrugated and rotating surfaces in 3D configuration with magnetic field, which covers a wide range of thermal engineering applications, are numerically simulated with finite element method. Effects of various pertinent parameters such as Richardson number (between 0.01 and 100), Hartmann number (between 0 and 1,000), angular rotational speed of the cylinder (between −30 and 30), solid nanoparticle volume fraction (between 0 and 0.04), corrugation height (between 0 and 0.18H) and number (between 1 and 20) on the convective heat transfer performance are numerically analyzed. Findings It was observed that the magnetic field suppresses the recirculation zone obtained in the lower part of the inlet port and enhances the average heat transfer rate, which is 10.77 per cent for water and 6.86 per cent for nanofluid at the highest strength. Due to the thermal and electrical conductivity enhancement of nanofluid, there is 5 per cent discrepancy in the Nusselt number augmentation with the nanoadditive inclusion in the absence and presence of magnetic field. The average heat transfer rate of the corrugated surface enhances by about 9.5 per cent for counter-clockwise rotation at angular rotational speed of 30 rad/s as compared to motionless cylinder case. Convective heat transfer characteristics are influenced by introducing the corrugation waves. As compared to number of waves, the height of the corrugation has a slight effect on the heat transfer variation. When the number of rectangular waves increases from N = 1 to N = 20, approximately 59 per cent of the average heat transfer reduction is achieved. Originality/value In this study, mixed convection of CuO-water nanofluid in a 3D vented cavity with inlet and outlet ports is numerically examined under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. To the best of authors knowledge such a study has never been performed. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticles, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above.
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Kuwabara, T., R. Matsumoto, and K. Shibata. "8.11. Magnetic avalanche model of mass supply in active galactic nuclei." Symposium - International Astronomical Union 184 (1998): 365–66. http://dx.doi.org/10.1017/s0074180900085247.
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We present the results of axisymmetric, two-dimentional magnetohydrodynamic (MHD) simulations of weakly ionized gas torus threaded by large scale vertical magnetic fields. The gas torus corresponds to the 100pc scale circumnuclear torus observed by HST in nearby AGNs (e.g. NGC4261) or 1010M⊙ circumnuclear gas found by CO observations in luminous IR galaxies and quasars (e.g. Scoville et al. 1991). The initial state of simulation is a constant angular momentum polytropic torus threaded by uniform vertical magnetic fields. The torus is assumed to be rotating in a static, spherical hot halo. The model parameters are Eth = vs02/(γvk02) = 5 ×10−3 and Eth = vA02/vK02 = 6.6×10−6 where γ is the adiabatic index and vs0 and va0 are the sound speed and the Alfvén speed at r = r0 respectively.
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KEAVENY, ERIC E., and MARTIN R. MAXEY. "Spiral swimming of an artificial micro-swimmer." Journal of Fluid Mechanics 598 (February 25, 2008): 293–319. http://dx.doi.org/10.1017/s0022112007009949.
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A device constructed from a filament of paramagnetic beads connected to a human red blood cell will swim when subject to an oscillating magnetic field. Bending waves propagate from the tip of the tail toward the red blood cell in a fashion analogous to flagellum beating, making the artificial swimmer a candidate for studying what has been referred to as ‘flexible oar’ micro-swimming. In this study, we demonstrate that under the influence of a rotating field the artificial swimmer will perform ‘corkscrew’-type swimming. We conduct numerical simulations of the swimmer where the paramagnetic tail is represented as a series of rigid spheres connected by flexible but inextensible links. An optimal range of parameters governing the relative strength of viscous, elastic and magnetic forces is identified for swimming speed. A parameterization of the motion is extracted and examined as a function of the driving frequency. With a continuous elastica/resistive force model, we obtain an expression for the swimming speed in the low-frequency limit. Using this expression we explore further the effects of the applied field, the ratio of the transverse field to the constant field, and the ratio of the radius of the sphere to the length of the filament tail on the resulting dynamics.
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Zhang, Jingrui, and Yanyan Li. "A Two-Dimensional Generalized Electromagnetothermoelastic Diffusion Problem for a Rotating Half-Space." Mathematical Problems in Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/964218.
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In the context of the theory of generalized thermoelastic diffusion, a two-dimensional generalized electromagnetothermoelastic problem with diffusion for a rotating half-space is investigated. The rotating half-space is placed in an external magnetic field with constant intensity and its bounding surface is subjected to a thermal shock and a chemical potential shock. The problem is formulated based on finite element method and the derived finite element equations are solved directly in time domain. The nondimensional temperature, displacement, stress, chemical potential, concentration, and induced magnetic field are obtained and illustrated graphically. The results show that all the considered variables have a nonzero value only in a bounded region and vanish identically outside this region, which fully demonstrates the nature of the finite speeds of thermoelastic wave and diffusive wave.
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Rao, Jian, Ke Wang, Boyu Wang, Qiongxuan Ge, Liming Shi, and Yaohua Li. "A special excitation system for analysis of coupling characteristics of thrust and levitation force of maglev train." Transportation Systems and Technology 4, no. 2 (September 13, 2018): 45–51. http://dx.doi.org/10.17816/transsyst20184245-51.
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Background: In the maglev train propelled by long stator linear synchronous motor (LSLSM), the thrust characteristics are one of important points to evaluate the performance of the system. However, coupling effect exists between the propulsion and levitation system. Therefore, the interference from the levitation system must be considered when the propulsion system is designed.
Aim: The article focus on the analysis of coupling characteristics of thrust and levitation force of maglev train, and a special excitation system is designed for the study.
Methods: In order to study the thrust performance under the fluctuating air gap field under laboratory conditions, a rotating synchronous motor has been designed to imitate the long stator linear synchronous motor applied in high speed maglev train. And a special excitation system is designed for the rotating synchronous motor, which can simulate the fluctuation of the exciting current during the actual operation of maglev train. The air gap of the rotating synchronous motor is kept as constant, and the fluctuating excitation current is added to the excitation winding of the rotating synchronous motor, thus the simulation of air gap magnetic field variation is achieved.
Results: The special excitation system of the experimental motor is introduced in detail.
Conclusion: The relationship between thrust and levitation force of long stator linear synchronous motor (LSLSM) in maglev train is strong coupling, non-linear, and dynamic. Complete decoupling of thrust and levitation force is not easy to be achieved. The experimental platform has been built to study the coupling characteristics of thrust and levitation force of maglev train.
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Bavassano, B., R. Bruno, and H. Rosenbauer. "Compressive fluctuations in the solar wind and their polytropic index." Annales Geophysicae 14, no. 5 (May 31, 1996): 510–17. http://dx.doi.org/10.1007/s00585-996-0510-z.
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Abstract. Magnetohydrodynamic compressive fluctuations of the interplanetary plasma in the region from 0.3 to 1 AU have been characterized in terms of their polytropic index. Following Chandrasekhar's approach to polytropic fluids, this index has been determined through a fit of the observed variations of density and temperature. At least three different classes of fluctuations have been identified: (1) variations at constant thermal pressure, in low-speed solar wind and without a significant dependence on distance, (2) adiabatic variations, mainly close to 1 AU and without a relevant dependence on wind speed, and (3) variations at nearly constant density, in fast wind close to 0.3 AU. Variations at constant thermal pressure are probably a subset of the ensemble of total-pressure balanced structures, corresponding to cases in which the magnetic field magnitude does not vary appreciably throughout the structure. In this case the pressure equilibrium has to be assured by its thermal component only. The variations may be related to small flow-tubes with approximately the same magnetic-field intensity, convected by the wind in conditions of pressure equilibrium. This feature is mainly observed in low-velocity solar wind, in agreement with the magnetic topology (small open flow-tubes emerging through an ensemble of closed structures) expected for the source region of slow wind. Variations of adiabatic type may be related to magnetosonic waves excited by pressure imbalances between contiguous flow-tubes. Such imbalances are probably built up by interactions between wind flows with different speeds in the spiral geometry induced by the solar rotation. This may account for the fact that they are mainly found at a large distance from the sun. Temperature variations at almost constant density are mostly found in fast flows close to the sun. These are the solar wind regions with the best examples of incompressible behaviour. They are characterized by very stable values for particle density and magnetic intensity, and by fluctuations of Alfvénic type. It is likely that temperature fluctuations in these regions are a remnant of thermal features in the low solar atmosphere. In conclusion, the polytropic index appears to be a useful tool to understand the nature of the compressive turbulence in the interplanetary plasma, as far as the frozen-in magnetic field does not play a crucial role.
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Said, Samia M. "Influence of the rotation on a generalized magneto-thermoelastic medium for three-phase-lag model." Multidiscipline Modeling in Materials and Structures 11, no. 2 (August 10, 2015): 297–318. http://dx.doi.org/10.1108/mmms-01-2015-0001.
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Purpose – The purpose of this paper is to investigate the effect of rotation and a magnetic field on the wave propagation in a generalized thermoelastic problem for a medium with an internal heat source that is moving with a constant speed. Design/methodology/approach – The formulation is applied to a generalized thermoelastic problem based on the three-phase-lag model and Green-Naghdi theory without energy dissipation. The medium is a homogeneous isotropic thermoelastic in the half-space. Findings – The exact expressions of the displacement components, temperature, and stress components are obtained by using normal mode analysis. Originality/value – Comparisons are made with the results predicted by the two models in the absence and presence of a magnetic field as well as a rotation. A comparison also is made with the results predicted by the two models for two different values of an internal heat source.
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Irasari, Pudji, Ketut Wirtayasa, Puji Widiyanto, Muhammad Fathul Hikmawan, and Muhammad Kasim. "Characteristics analysis of interior and inset type permanent magnet motors for electric vehicle applications." Journal of Mechatronics, Electrical Power, and Vehicular Technology 12, no. 1 (July 31, 2021): 1–9. http://dx.doi.org/10.14203/j.mev.2021.v12.1-9.
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Permanent magnet motors (PMMs) are widely used in electric vehicles because of their benefits. Based on the permanent magnet topologies on the rotor, PMMs are classified into three types: surface mounted PMM, inset PMM, and interior PMM. This paper discusses a comparison of the characteristics of interior and inset types of PMMs for electric vehicle applications. The study aims to find out the effect of the rotor construction on the magnetic characteristics, torque-speed characteristics, and cogging torque. Simulations were carried out analytically and numerically using the FEMM 4.2 software. The simulation results at the base speed show that the interior PMM generates a higher torque but with a lower rotation, namely 56.47 Nm and 3162 rpm, respectively, while the inset PMM produces higher rotation 4200 rpm but lower output torque of 46.01 Nm. However, with a higher saliency ratio, the interior PMM produces higher maximum torque and speed at both constant torque and field weakening regions than the PMM inset, which is 92.87 Nm and 6310 rpm, consecutively. In terms of cogging torque, the interior PMM raises it slightly higher (2.90 Nm) than the inset PMM (1.93 Nm). The results conclude that, in general, the interior PMM shows better performance in all studied regions and is preferable for electric vehicle applications.
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Erofeev, V. I., A. V. Shekoyan, and M. V. Belubekyan. "SPATIALLY-LOCALIZED NONLINEAR MAGNETOELASTIC WAVES IN A MICROPOLAR ELECTRICAL CONDUCTING MEDIUM." Problems of strenght and plasticity 81, no. 4 (2019): 402–15. http://dx.doi.org/10.32326/1814-9146-2019-81-4-402-415.
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A nonlinear model of an electrically conducting micropolar medium interacting with an external magnetic field is proposed. The deformable state of such a medium is described by two asymmetric tensors: tensor of deformations and bending-torsion tensor. In both tensors, linear and nonlinear terms are taken into account in rotation gradients and displacement gradients (geometric nonlinearity). The components of the bending-torsion tensor, which have identical indices, describe torsional deformations, and the rest - bending deformations. The stress state of the medium is described by two asymmetric tensors: stress tensor and moment stress tensor. It is assumed, as it is usual in magnetoelasticity, that the action of the electromagnetic field on the deformation field occurs through the Lorentz forces. From the system of Maxwell equations follow the equations for electrical and magnetic inductions, which, together with the electromagnetic equations of state, must be added to the equations of the dynamics of a micropolar medium. Within the framework of the proposed model, a one-dimensional nonlinear shear-rotation magnetoelastic wave is considered. The nonlinear term is selected and taken into account in the equations of dynamics, making the most significant contribution to wave processes. It is shown that two factors will influence the wave propagation: dispersion and nonlinearity. Nonlinearity leads to the emergence of new harmonics in the wave, which contributes to the appearance of a sharp drop in the moving profile. The dispersion, on the contrary, smoothes the differences due to the difference in the phase velocities of the harmonic components of the waves. The combined effect of these factors can lead to the formation of stationary waves that propagate at a constant speed without changing the shape. Only those cases are physically feasible when there is no constant component in the deformation wave. Stationary waves can be both periodic and aperiodic. The latter are spatially localized waves - solitons. It is shown that the behavior of "subsonic" and “supersonic” solitons will be qualitatively different.
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Brookfield, D. J., and Z. B. Dlodlo. "Transfer Function Identification of an Electro-Rheological Actuator." International Journal of Modern Physics B 10, no. 23n24 (October 30, 1996): 3115–32. http://dx.doi.org/10.1142/s0217979296001562.
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A fluid clutch utilising an Electro-Rheological (ER) suspension provides a controlled torque coupling between input and output through the control of the applied electric field. If the input is driven at constant speed the device can be considered as an ER torque actuator and thus be used to drive robot links or other mechanisms requiring precise positioning. Such an ER torque actuator can replace a DC servo-motor in robotic applications with the benefits of low time constant and smooth output torque unaffected by cogging (i.e. variation in torque of a DC motor as the magnetic reluctance of the armature-stator path changes with rotation). Although the ER actuator has many benefits, it suffers from a non-linear and time varying relationship between input voltage and output torque. These undesirable characteristics can be mitigated by providing a local closed loop controller around the system. The design of such a controller requires a knowledge of the relationship between the applied voltage and output torque; i.e. the transfer function of the actuator. This transfer function has been determined by observing the response of an ER torque actuator in the frequency domain. It is shown that a linear transfer function model reasonable represents the actuator behaviour, that the actuator is a stable second order system and that the time constant of the clutch studied is sufficiently short to hold considerable promise for robotic applications. Furthermore, the maximum torque capability is shown to be sufficient for many medium scale industrial robots.
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Soiolmaa, Ts, N. Sugir-Erdene, D. Baasanzhav, L. Munkhtuul, and E. Otgonzhargal. "Comparative study on concentration properties of iron deposits (Mongolia)." Izvestiya vysshikh uchebnykh zavedenii Gornyi zhurnal, no. 2 (March 30, 2020): 44–51. http://dx.doi.org/10.21440/0536-1028-2020-2-44-51.
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Research aims to compare magnetic flotation results of iron deposits of Mongolia in order to obtain iron concentrate with low sulfur content that meets the standard of raw materials for metallurgical production. Research methodology. Representative samples were taken from Tumurtei deposit in Khuder soum (Selenge province), Tumur Tolgoi deposit (Darkhan-Uul province) and Chandmani Uul deposit (Dornogobi province). Iron grade in the primary ore from Tumurtei deposit was 42.03%, in Tumurtolgoi ore – 46.57% and in Chandmani-Uul ore–43.59%. The ore was crushed into 1 mm size through java crusher and gyratory crusher for the first stage. Dry magnetic concentration was conducted on the ore samples using Boxmag Rapid LR-1.4 Induced Magnetic Separator (the UK). The test work was conducted under the condition when the distance between gyrator of separator and rotation speed are constant and by this time magnetic strength was changed. At the next stage the concentrate of dry magnetic concentration was processed by wet magnetic separation. In order to reduce the sulfur content in the ore from Tumur tolgoi and Tumurtei deposits, flotation experiments were also conducted using UK Denver flotation machine. Ore and concentrator grade were determined using traditional titer method and X-ray fluorescence spectrometer (XRF), the mineral contents was analyzed by X-ray powder diffraction (XRD), elements in product of wet magnetic separator and final concentrate were analyzed using SEM-EDX, the thermal-gravy meter analysis was conducted using instrument TG/DTA7300. Results. Wet magnetic concentration of dry magnetic separation concentrates of all the studied ore allow obtaining concentrates with the high content of iron – from 64% to 66%. Flotation of the concentrate of wet magnetic concentration made it possible to reach iron content in Tumurtei and Tumurtolgoi deposits of 69.02% and 62.86% correspondingly and reduce Sulphur content to 0.2%, 0.48% correspondingly. This study covers the field of flotation technology to extract products with lower sulfur content which meet standard of modern metallurgical industry.
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Chumanov, I. V., I. A. Alekseev, and D. V. Sergeev. "Modeling the behavior of direct current electromagnetic forces acting on a drop of liquid metal during electroslag remelting." Izvestiya. Ferrous Metallurgy 64, no. 7 (August 28, 2021): 530–35. http://dx.doi.org/10.17073/0368-0797-2021-7-530-535.
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The article presents mathematical and computer modeling of the behavior of liquid electrode metal drops during the process of electroslag remelting (ESP) at a constant current source. The study of the effect of electric field created by direct current allowed us to show the deviation of the drop trajectory from the electrode axis. The flow of electrons and drops of the electrode metal are exposed to electromagnetic forces, which leads to their displacement relative to the remelted electrode axis. This effect entails destabilization of the liquid metal bath and crystal heterogeneity. In turn, the use of external influence on the flow of ESR process can make it possible to stabilize the liquid metal bath even with the use of direct current. Centrifugal forces can act as such forces. They can arise when implementing the technology with the consumable electrode rotation around its own axis. To establish the optimal parameters of rotation speed, it is necessary to estimate the magnitude of impact of the magnetic field that occurs during direct current remelting process. The modeling was carried out using the Ansys Fluent 16.0 software package on the example of remelting 12Kh18N10T steel under the flux ANF-6. The algorithm for calculating of Ansys Fluent is based on the finite element method. In this paper, the mathematical apparatus was not changed and was used in its initial form. The method of magnetic induction was used. The database of information about the ongoing process was built on a grid of finite elements with certain, but sufficient level of adequacy and quality. Each element contains information about the model at a given point, specified for this modeling process. We have revealed the change in the trajectory of the electrode metal drop by electric field from the opposite direction along which the drop flows. The average length of the path traversed by liquid metal drop from the mold axis to the inner surface is from 5 to 15 cm. The motion of an electrode metal drop without an external magnetic field was simulated. This simulation made it possible to determine (estimate) the direction of movement of electrode metal drops and the indicator of necessary external force to stabilize the liquid metal bath during ESP process at direct current equal to 0.067 N.
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Käpylä, P. J. "Overshooting in simulations of compressible convection." Astronomy & Astrophysics 631 (November 2019): A122. http://dx.doi.org/10.1051/0004-6361/201834921.
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Context. Convective motions that overshoot into regions that are formally convectively stable cause extended mixing. Aims. We aim to determine the scaling of the overshooting depth (dos) at the base of the convection zone as a function of imposed energy flux (ℱn) and to estimate the extent of overshooting at the base of the solar convection zone. Methods. Three-dimensional Cartesian simulations of hydrodynamic compressible non-rotating convection with unstable and stable layers were used. The simulations used either a fixed heat conduction profile or a temperature- and density-dependent formulation based on Kramers opacity law. The simulations covered a range of almost four orders of magnitude in the imposed flux, and the sub-grid scale diffusivities were varied so as to maintain approximately constant supercriticality at each flux. Results. A smooth heat conduction profile (either fixed or through Kramers opacity law) leads to a relatively shallow power law with dos ∝ ℱn0.08 for low ℱn. A fixed step-profile of the heat conductivity at the bottom of the convection zone leads to a somewhat steeper dependency on dos ∝ ℱn0.12 in the same regime. Experiments with and without subgrid-scale entropy diffusion revealed a strong dependence on the effective Prandtl number, which is likely to explain the steep power laws as a function of ℱn reported in the literature. Furthermore, changing the heat conductivity artificially in the radiative and overshoot layers to speed up thermal saturation is shown to lead to a substantial underestimation of the overshooting depth. Conclusions. Extrapolating from the results obtained with smooth heat conductivity profiles, which are the most realistic set-up we considered, suggest that the overshooting depth for the solar energy flux is about 20% of the pressure scale height at the base of the convection zone. This is two to four times higher than the estimates from helioseismology. However, the current simulations do not include rotation or magnetic fields, which are known to reduce convective overshooting.
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Metelkov, Vladimir P., and Yakov L. Liberman. "Сhoosing the Belt Conveyor Start Mode." Electrotechnical Systems and Complexes, no. 2(43) (June 28, 2019): 54–59. http://dx.doi.org/10.18503/2311-8318-2019-2(43)-54-59.
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The paper is concerned with the problems associated with starting a long conveyor driven by an induction motor. We consider the dynamic loads in the conveyor belt during start-up, which cause slippage of the conveyor belt on the traction drum leading to its premature deterioration. The relevance of the topic is associated with the high cost of the conveyor belt reaching 60% of the cost of the entire conveyor and more. The aim of the work is to ascertain the possibilities of reducing the wear of the conveyor belt, for example, through the use of the possibilities provided by the system of the electric drive. The possibility of reducing the probability of the conveyor belt slippage by increasing the initial belt tension is noted. However, constant high tension also accelerates belt deterioration. To solve this problem, the use of automatic tension control devices is proposed, as well as the reduction of dynamic loads in the belt by using soft starters based on a thyristor voltage converter, which regulates the amplitude of voltage on the motor stator. The features of an asynchronous motor heating when starting with a constant speed of rotation of the magnetic field are discussed. The interrelation between the start-up duration and the motor stator winding heating with the dynamic loads occurring in the conveyor belt in start-up modes is considered. Modeling results obtained using the Simulink package are presented. Since long start-up modes of asynchronous electric drives based on thyristor voltage converters can lead to motor overheating, especially when the conveyor is restarted under full load and in hot climates, it is advisable to use automatic conveyor belt tension control devices during start-up modes thereby reducing premature belt deterioration together with a decrease in the conveyor motor heating.
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Goodman, Michael L. "Driven, dissipative, energy-conserving magnetohydrodynamic equilibria. Part 2. The screw pinch." Journal of Plasma Physics 49, no. 1 (February 1993): 125–59. http://dx.doi.org/10.1017/s002237780001686x.
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A cylindrically symmetric, electrically driven, dissipative, energy-conserving magnetohydrodynamic equilibrium model is considered. The high-magneticfield Braginskii ion thermal conductivity perpendicular to the local magnetic field and the complete electron resistivity tensor are included in an energy equation and in Ohm's law. The expressions for the resistivity tensor and thermal conductivity depend on number density, temperature, and the poloidal and axial (z-component) magnetic field, which are functions of radius that are obtained as part of the equilibrium solution. The model has plasma-confining solutions, by which is meant solutions characterized by the separation of the plasma into two concentric regions separated by a transition region that is an internal boundary layer. The inner region is the region of confined plasma, and the outer region is the region of unconfined plasma. The inner region has average values of temperature, pressure, and axial and poloidal current densities that are orders of magnitude larger than in the outer region. The temperature, axial current density and pressure gradient vary rapidly by orders of magnitude in the transition region. The number density, thermal conductivity and Dreicer electric field have a global minimum in the transition region, while the Hall resistivity, Alfvén speed, normalized charge separation, Debye length, (ωλ)ion and the radial electric field have global maxima in the transition region. As a result of the Hall and electron-pressure-gradient effects, the transition region is an electric dipole layer in which the normalized charge separation is localized and in which the radial electric field can be large. The model has an intrinsic value of β, about 13·3%, which must be exceeded in order that a plasma-confining solution exist. The model has an intrinsic length scale that, for plasma-confining solutions, is a measure of the thickness of the boundary-layer transition region. If appropriate boundary conditions are given at R = 0 then the equilibrium is uniquely determined. If appropriate boundary conditions are given at any outer boundary R = a then the equilibrium exhibits a bifurcation into two states, one of which exhibits plasma confinement and carries a larger axial current than the other, which is almost homogeneous and cannot confine a plasma. Exact expressions for the two values of the axial current in the bifurcation are derived. If the boundary conditions are given at R = a then a solution exists if and only if the constant driving electric field exceeds a critical value. An exact expression for this critical electric field is derived. It is conjectured that the bifurcation is associated with an electric-field-driven transition in a real plasma, between states with different rotation rates, energy dissipation rates and confinement properties. Such a transition may serve as a relatively simple example of the L—H mode transition observed in tokamaks.
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Arif, Syed Javed, M. S. Jamil Asghar, and A. Imdadullah. "Very Fast Measurement of Low Speed of Rotating Machines Using Rotating Magnetic Field." IEEE Transactions on Instrumentation and Measurement 61, no. 3 (March 2012): 759–66. http://dx.doi.org/10.1109/tim.2011.2170914.
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TAO, R., and Y. C. LAN. "INTERACTIONS BETWEEN TWO ROTATING POLARIZED SPHERES." International Journal of Modern Physics B 19, no. 07n09 (April 10, 2005): 1215–21. http://dx.doi.org/10.1142/s0217979205030098.
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Precise measurement of the attracting force between two spheres inside an electric field indicates that the rotation of one sphere along the axis perpendicular to the electric field reduces the attracting force between them. This reduction becomes smaller as the distance between the two spheres increases. In the limit of infinite rotational speed, the attracting force seems to tend to a non-zero constant.
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Alvarez, A., P. Suarez, D. Caceres, E. Cordero, J. M. Ceballos, and B. Perez. "Disk-Shaped Superconducting Rotor Under a Rotating Magnetic Field: Speed Dependence." IEEE Transactions on Appiled Superconductivity 15, no. 2 (June 2005): 2174–77. http://dx.doi.org/10.1109/tasc.2005.849605.
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Arif, Syed Javed, Mohammad S. Jamil Asghar, and Adil Sarwar. "Measurement of Speed and Calibration of Tachometers Using Rotating Magnetic Field." IEEE Transactions on Instrumentation and Measurement 63, no. 4 (April 2014): 848–58. http://dx.doi.org/10.1109/tim.2013.2283136.
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Zhang, Xiaoyun, Zhenguo Luo, Xiaoyang He, Qingguo Han, and Weide Zhang. "Molecular mechanism of effect of rotating constant magnetic field on organisms." Science in China Series C: Life Sciences 44, no. 5 (October 2001): 554–60. http://dx.doi.org/10.1007/bf02882398.
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Odngam, Soontorn, Chaiyut Preecha, Prapaiwan Sanwong, Woramet Thongtan, and Jiraphon Srisertpol. "Precision Analysis and Design of Rotating Coil Magnetic Measurements System." Applied Sciences 10, no. 23 (November 27, 2020): 8454. http://dx.doi.org/10.3390/app10238454.
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This research presents the design and construction of measuring instruments for a dipole magnetic field using a rotating coil technique. This technique is a closed-loop speed-control system where a Proportional-Integral (PI) controller works together with the intensity measurement of the magnetic field through the rotating coil. It was used to analyze the impact on the accuracy of the electromagnetic at speed ranges of 60, 90, and 120 rpm. The error estimation in the measurement of the normal dipole and skew dipole magnet caused by the steady-state error of the speed control system and the rotational search coil in whirling motion are demonstrated. Rotating unbalance, shaft coupling, and misalignment from its setup disturbed the performance of the speed control system as a nonlinear system.
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He, Yong Jun, Xue Chen, and Ziad Moumni. "3D Energy Analysis of Magnetic-Field Induced Martensite Reorientation in Magnetic Shape Memory Alloys." Materials Science Forum 738-739 (January 2013): 400–404. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.400.
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This paper explains the magnetic-field induced martensite reorientation in Ferromagnetic Shape Memory Alloys (FSMA) through a simple energy analysis from which the role of the martensite’s magnetic anisotropy is emphasized. In particularly, with a three-dimensional (3D) energy analysis, we study the switching between the three tetragonal martensite variants driven by a rotating magnetic field (with a constant magnitude) and a non-rotating magnetic field (with a fixed direction but varying magnitudes). Finally, a simple planar phase diagram is proposed to describe the martensite reorientation in general 3D loadings.
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Terrero, Diana Alvear, Daryel Manreza Paret, and Aurora Pérez Martínez. "On Slowly Rotating Magnetized White Dwarfs." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760025. http://dx.doi.org/10.1142/s2010194517600254.
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Rotating magnetized white dwarfs are studied within the framework of general relativity using Hartle’s formalism. Matter inside magnetized white dwarfs is described by an equation of state of particles under the action of a constant magnetic field which introduces anisotropic pressures. Our study is done for values of magnetic field below [Formula: see text] G - a threshold of the maximum magnetic field obtained by the cylindrical metric solution - and typical densities of WDs. The effects of the rotation and magnetic field combined are discussed, we compute relevant magnitudes such as the moment of inertia, quadrupole moment and eccentricity.
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Yeh, Kai-Yuan, and R. P. S. Han. "Analysis of High-Speed Rotating Disks With Variable Thickness and Inhomogeneity." Journal of Applied Mechanics 61, no. 1 (March 1, 1994): 186–91. http://dx.doi.org/10.1115/1.2901396.
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A rotating disk with varying thickness and inhomogeneity, and subjected to a steady, inhomogeneous temperature field is analyzed. To handle the arbitrary profile, the disk is discretized into a series of uniform annular disks possessing constant material properties and then solved by the step-reduction method. Analytic expressions for thermoelastic stresses are given, and based on these results, the formulation is extended to include the calculation of shrink fit, the solving of the inverse problem for equistrength rotating disks, and the computations of plastic stresses and creep at elevated temperatures.
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KLEEORIN, N., I. ROGACHEVSKII, A. RUZMAIKIN, A. M. SOWARD, and S. STARCHENKO. "Axisymmetric flow between differentially rotating spheres in a dipole magnetic field." Journal of Fluid Mechanics 344 (August 10, 1997): 213–44. http://dx.doi.org/10.1017/s0022112097006034.
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Constant-density electrically conducting fluid is confined to a rapidly rotating spherical shell and is permeated by an axisymmetric potential magnetic field with dipole parity; the regions outside the shell are rigid insulators. Slow steady axisymmetric motion is driven by rotating the inner sphere at a slightly slower rate. Linear solutions of the governing magnetohydrodynamic equations are derived in the small Ekman number E-limit for values of the Elsasser number Λ less than order unity. Attention is restricted to the mainstream outside the Ekman–Hartmann layers adjacent to the inner and outer boundaries.
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Yu, Shimin, Ningze Ma, Hao Yu, Haoran Sun, Xiaocong Chang, Zhiguang Wu, Jiaxuan Deng, et al. "Self-Propelled Janus Microdimer Swimmers under a Rotating Magnetic Field." Nanomaterials 9, no. 12 (November 22, 2019): 1672. http://dx.doi.org/10.3390/nano9121672.
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Recent strides in micro- and nanofabrication technology have enabled researchers to design and develop new micro- and nanorobots for biomedicine and environmental monitoring. Due to its non-invasive remote actuation and convenient navigation abilities, magnetic propulsion has been widely used in micro- and nanoscale robotic systems. In this article, a highly efficient Janus microdimer swimmer propelled by a rotating uniform magnetic field was investigated experimentally and numerically. The velocity of the Janus microdimer swimmer can be modulated by adjusting the magnetic field frequency with a maximum speed of 133 μm·s−1 (≈13.3 body length s−1) at the frequency of 32 Hz. Fast and accurate navigation of these Janus microdimer swimmers in complex environments and near obstacles was also demonstrated. This efficient propulsion behavior of the new Janus microdimer swimmer holds considerable promise for diverse future practical applications ranging from nanoscale manipulation and assembly to nanomedicine.
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Luo, Wei, Jindan Yan, Yali Tan, Huiru Ma, and Jianguo Guan. "Rotating 1-D magnetic photonic crystal balls with a tunable lattice constant." Nanoscale 9, no. 27 (2017): 9548–55. http://dx.doi.org/10.1039/c7nr03335d.
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Heng, Lida, Cheng Yin, Seok Han, Jun Song, and Sang Mun. "Development of a New Ultra-High-Precision Magnetic Abrasive Finishing for Wire Material Using a Rotating Magnetic Field." Materials 12, no. 2 (January 20, 2019): 312. http://dx.doi.org/10.3390/ma12020312.
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In this paper, we propose a new ultra-high-precision magnetic abrasive finishing method for wire material which is considered to be difficult with the existing finishing process. The processing method uses a rotating magnetic field system with unbonded magnetic abrasive type. It is believed that this process can efficiently perform the ultra-high-precision finishing for producing a smooth surface finish and removing a diameter of wire material. For such a processing improvement, the following parameters are considered; rotational speed of rotating magnetic field, vibration frequency of wire material, and unbonded magnetic abrasive grain size. In order to evaluate the performance of the new finishing process for the wire material, the American Iron and Steel Institute (AISI) 1085 steel wire was used as the wire workpiece. The experimental results showed that the original surface roughness of AISI 1085 steel wire was enhanced from 0.25 µm to 0.02 µm for 60 s at 800 rpm of rotational speed. Also, the performance of the removed diameter was excellent. As the result, a new ultra-high-precision magnetic abrasive finishing using a rotating magnetic field with unbonded magnetic abrasive type could be successfully adopted for improving the surface roughness and removing the diameter of AISI 1085 steel wire material.
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Bakhtiyarov, Sayavur I., Mihai Dupac, Ruel A. Overfelt, and Sorin G. Teodorescu. "On Electrical Conductivity Measurements of Molten Metals by Inductive Technique." Journal of Fluids Engineering 126, no. 3 (May 1, 2004): 468–70. http://dx.doi.org/10.1115/1.1760542.
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In this paper, we propose a new relationship between the opposing mechanical torque and the electric conductivity of a rotating liquid specimen in a permanent external magnetic field of constant induction, which includes the effect of fluid flow. The proposed relationship was applied to describe the experimental data for a conductive specimens rotating in a permanent magnetic field.
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Okada, Y., B. Nagai, and T. Shimane. "Cross-Feedback Stabilization of the Digitally Controlled Magnetic Bearing." Journal of Vibration and Acoustics 114, no. 1 (January 1, 1992): 54–59. http://dx.doi.org/10.1115/1.2930234.
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A method of stabilizing a high speed rotor supported by magnetic bearings is presented. The magnetic bearing is controlled by a digital controller with rotationally synchronized interruption. The main problem with the rotating disc is the cross-coupling effect caused by the gyroscopic or inductive forces which sometimes make the high speed rotor unstable. Standard PID control is carried out with constant time interval interruption, while the rotational interrupt subroutine performs the cross-coupling feedback. The cross-feedback in the x-y directions well compensates for the undesirable coupling effect. This scheme is applied to a four-mass, two-bearing rotor system and its capability is tested.
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Tao, Jing Qing, Lin Dong, Zhei Wei Liu, and Jie Yang. "Effect of Normal Pressure on the Coupled Temperature Field of Pin-Disc in Electromagnetic Environment." Advanced Materials Research 941-944 (June 2014): 2436–39. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2436.
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Based on the FE software ANSYS, the coupling temperature fields of pin-disc friction pair were simulated and analyzed in pin-disc friction rig. The results show that the temperatures of pin-disc friction pair with magnetic field are higher than that without magnetic field, under the same relative displacement, speed and normal pressure. The maximum coupling temperature increase slowly and then increase quickly with the increasing of normal pressure, under the constant magnetic field intensity and speed. The maximum coupling temperature decreases with the increase of relative speed, when the relative sliding distance and magnetic field intensity are constant.
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Sharma, Praveen Kumar, Shraddha Argal, Anita Tiwari, and Ram Prasad Prajapati. "Jeans Instability of Rotating Viscoelastic Fluid in the Presence of Magnetic Field." Zeitschrift für Naturforschung A 70, no. 1 (January 1, 2015): 39–45. http://dx.doi.org/10.1515/zna-2014-0229.
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AbstractThe Jeans instability of rotating viscoelastic fluid in the presence of uniform magnetic field is investigated using the generalised hydrodynamic (GH) model. A general dispersion relation is derived with the help of linearised perturbation equations using the normal mode analysis, which is further discussed for axis of rotation parallel and perpendicular to the direction of the magnetic field in both the weakly coupled (hydrodynamic) and strongly coupled (kinetic) limits. The onset criterion of Jeans instability for magnetised rotating viscoelastic fluid is obtained, which remains unaffected by the presence of rotation and magnetic field but depends upon viscoelastic effects. The graphical illustrations are depicted to see the influence of rotation, Mach number, shear and viscous effects, and sound speed on the growth rate of Jeans instability. It is found that all these parameters have stabilising influence on the growth rate of Jeans instability; hence, they are capable of collapsing to a self-gravitating, rotating, magnetised viscoelastic medium.
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Landry, Brad, Victoria Girgis, and John G. Gibbs. "Controlling the Speed of Light‐Activated Colloids with a Constant, Uniform Magnetic Field." Small 16, no. 35 (August 6, 2020): 2003375. http://dx.doi.org/10.1002/smll.202003375.
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Spakovszky, Z. S., J. D. Paduano, R. Larsonneur, A. Traxler, and M. M. Bright. "Tip Clearance Actuation With Magnetic Bearings for High-Speed Compressor Stall Control." Journal of Turbomachinery 123, no. 3 (February 1, 2000): 464–72. http://dx.doi.org/10.1115/1.1370163.
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Magnetic bearings are widely used as active suspension devices in rotating machinery, mainly for active vibration control purposes. The concept of active tip-clearance control suggests a new application of magnetic bearings as servo-actuators to stabilize rotating stall in axial compressors. This paper presents a first-of-a-kind feasibility study of an active stall control experiment with a magnetic bearing servo-actuator in the NASA Glenn high-speed single-stage compressor test facility. Together with CFD and experimental data a two-dimensional, incompressible compressor stability model was used in a stochastic estimation and control analysis to determine the required magnetic bearing performance for compressor stall control. The resulting requirements introduced new challenges to the magnetic bearing actuator design. A magnetic bearing servo-actuator was designed that fulfilled the performance specifications. Control laws were then developed to stabilize the compressor shaft. In a second control loop, a constant gain controller was implemented to stabilize rotating stall. A detailed closed loop simulation at 100 percent corrected design speed resulted in a 2.3 percent reduction of stalling mass flow, which is comparable to results obtained in the same compressor by Weigl et al. (1998. ASME J. Turbomach. 120, 625–636) using unsteady air injection. The design and simulation results presented here establish the viability of magnetic bearings for stall control in aero-engine high-speed compressors. Furthermore, the paper outlines a general design procedure to develop magnetic bearing servo-actuators for high-speed turbomachinery.
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Mateev, Valentin, and Iliana Marinova. "Magnetic Elastomer Sensor for Dynamic Torque and Speed Measurements." Electronics 10, no. 3 (January 28, 2021): 309. http://dx.doi.org/10.3390/electronics10030309.
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In this paper is proposed a dynamic torque, rotational speed, and shaft position sensor. It is built of magnetic elastomer coating directly applied over a rotating shaft. The sensor is used for precise measurements of changes in torque and speed, and it is usable at high rotational speeds, directly on the device shaft. The sensor is based on magnetic elastomer material deformation and the corresponding change in magnetic field amplitude and direction. The proposed sensor design is simple and can acquire reliable readings for a wide range of rotational speeds. Sensor design consists of the following: magnetic elastomer coating with nanoparticles, in which, elastomer is used for a sensing convertor; magneto-resistive linear field sensor; and microprocessor unit for calibration and control. Numerical and experimental test results are demonstrated and analyzed. Sensor implementation aims to meet magnetic mechatronic systems’ specific requirements.
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Yao, Xin Gai, Shi Ying Wang, Yan Hong Ding, Gang Ya, and Jie Zhang. "Study of Finishing Internal Surface Using Magnetic Force Generated by Rotating Magnetic Field in Electromotor." Key Engineering Materials 359-360 (November 2007): 295–99. http://dx.doi.org/10.4028/www.scientific.net/kem.359-360.295.
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In the paper, a new method of using rotating magnetic field generated by a stator of alternative electromotor to polish the inner surface of tube-type workpieces is proposed; a finishing device using the stator construction and inverter is designed; the finishing mechanism is analyzed and experiments are carried out. Experimental investigations show that filling amount of magnetic abrasive influences the surface roughness of workpiece directly and have an optimal value. The higher magnetic conductivity is, and the finer finishing effect is. The attraction force of magnetic particles depends on intensity of magnetic induction directly and has the optimal value. The higher the rotation speed is, and the lower the value of surface roughness. Under the optimal experimental condition, the new method can reduce the value of surface roughness more than 2 grades. Therefore, this technique has prospective application future.
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Kovács, Jenő, Arnold Rónaföldi, and András Roósz. "Unidirectional Solidification of Pb-Sn Alloys in a Rotating Magnetic Field." Materials Science Forum 790-791 (May 2014): 408–13. http://dx.doi.org/10.4028/www.scientific.net/msf.790-791.408.
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Cylindrical Pb-Sn alloy samples (diameter: 8 mm, length: 120 mm) of different compositions (30, 40 and 50 wt.% of Sn) were prepared from high pure (4N) components. The unidirectional solidification experiments have been performed according to the upward vertical Bridgman-method by using a rotating magnetic field (RMF) with a magnetic induction of 150 mT and with a frequency of 50 Hz. The sample-movement velocity was constant (0.05 mm/s) and the temperature gradient changed from 7 to 3 K/mm during the solidification process. The first half of samples was solidified without using the magnetic field and the second half was solidified by using the magnetic field. Under the influence of this strong flow induced by the magnetic field, the columnar microstructure of the first part decomposed and a characteristic "Christmas tree"- like macrosegregated structure with equiaxed Pb-dendrites was developed. The secondary dendrite arm spacing (SDAS) and the volume percent of primary Pb-phase (dendrite) were measured by an automatic image analyser on the longitudinal polished sections along the whole length of the samples. The effect of the forced melt flow on the micro-and macrostructure was studied in case of the different sample compositions.
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Vargas-Rodríguez, H., A. Gallegos, M. A. Muñiz-Torres, H. C. Rosu, and P. J. Domínguez. "Relativistic Rotating Electromagnetic Fields." Advances in High Energy Physics 2020 (December 29, 2020): 1–17. http://dx.doi.org/10.1155/2020/9084046.
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In this work, we consider axially symmetric stationary electromagnetic fields in the framework of special relativity. These fields have an angular momentum density in the reference frame at rest with respect to the axis of symmetry; their Poynting vector form closed integral lines around the symmetry axis. In order to describe the state of motion of the electromagnetic field, two sets of observers are introduced: the inertial set, whose members are at rest with the symmetry axis; and the noninertial set, whose members are rotating around the symmetry axis. The rotating observers measure no Poynting vector, and they are considered as comoving with the electromagnetic field. Using explicit calculations in the covariant 3 + 1 splitting formalism, the velocity field of the rotating observers is determined and interpreted as that of the electromagnetic field. The considerations of the rotating observers split in two cases, for pure fields and impure fields, respectively. Moreover, in each case, each family of rotating observers splits in two subcases, due to regions where the electromagnetic field rotates with the speed of light. These regions are generalizations of the light cylinders found around magnetized neutron stars. In both cases, we give the explicit expressions for the corresponding velocity fields. Several examples of relevance in astrophysics and cosmology are presented, such as the rotating point magnetic dipoles and a superposition of a Coulomb electric field with the field of a point magnetic dipole.
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Núñez, Manuel. "An Analytic Study of the Reversal of Hartmann Flows by Rotating Magnetic Fields." International Journal of Mathematics and Mathematical Sciences 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/641738.
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The effects of a background uniform rotating magnetic field acting in a conducting fluid with a parallel flow are studied analytically. The stationary version with a transversal magnetic field is well known as generating Hartmann boundary layers. The Lorentz force includes now one term depending on the rotation speed and the distance to the boundary wall. As one intuitively expects, the rotation of magnetic field lines pushes backwards or forwards the flow. One consequence is that near the wall the flow will eventually reverse its direction, provided the rate of rotation and/or the magnetic field are large enough. The configuration could also describe a fixed magnetic field and a rotating flow.
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Li, Qian, Xiaojun Liu, Ming Chang, and Zhen Lu. "Thrombolysis Enhancing by Magnetic Manipulation of Fe3O4 Nanoparticles." Materials 11, no. 11 (November 17, 2018): 2313. http://dx.doi.org/10.3390/ma11112313.
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In this paper, an effective method of accelerating urokinase-administrated thrombolysis through a rotating magnetic field (RMF) of guided magnetic nanoparticles (NPs) in the presence of low-dose urokinase is proposed. The dispersed Fe3O4 NPs mixed with urokinase were injected into microfluidic channels occluded by thrombus prepared in vitro. These magnetic NPs aggregated into elongated clusters under a static magnetic field, and were then driven by the RMF. The rotation of Fe3O4 aggregates produced a vortex to enhance the diffusion of urokinase to the surface of the thrombus and accelerate its dissolution. A theoretical model based on convective diffusion was constructed to describe the thrombolysis mechanism. The thrombus lysis speed was determined according to the change of the thrombus dissolution length with time in the microfluidic channel. The experimental results showed that the thrombolysis speed with rotating magnetic NPs is significantly increased by nearly two times compared with using the same dose of pure urokinase. This means that the magnetically-controlled NPs approach provides a feasible way to achieve a high thrombolytic rate with low-dose urokinase in use.
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Ecsedi, István, and Ákos József Lengyel. "Deformation of rotating two-layer curved composite beams." Curved and Layered Structures 6, no. 1 (January 1, 2019): 181–91. http://dx.doi.org/10.1515/cls-2019-0015.
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AbstractAn analytical solution is presented for the determination of the deformation of rotating two-layer composite beams. The direction of axis of rotation is vertical and the speed of rotation is constant. The axis of rotation is in the plane of symmetry of curved beam. The source of the in-plane deformation is the stationary rotation of the curved beam. The plane of the curvature is the symmetry plane of the curved beam for its material, geometrical and supporting properties. Assumed form of the displacement field meets the prescriptions of the classical Euler-Bernoulli beam theory. Examples illustrate the applications of the presented analytical solution.
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Phan, Manh-Huong, and David Mandrus. "Cooling achieved by rotating an anisotropic superconductor in a constant magnetic field: A new perspective." AIP Advances 6, no. 12 (December 2016): 125022. http://dx.doi.org/10.1063/1.4972124.
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Yao, P. X., H. L. Chen, Jian Mei Wang, Shu Cai Yang, and Y. X. Zhang. "The Principle of Magnetic Abrasive Finishing under Rotating Electromagnetic Field and Its Application in Surface Finishing of Heavy Crankshaft." Key Engineering Materials 304-305 (February 2006): 379–83. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.379.
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Magnetic abrasive finishing (MAF) is a processing technology using magnetic abrasive grain (MAG) under magnetic field to finish surface of workpiece. The magnetic fields used in MAF include permanent magnetic field and electromagnetic field. Two conditions must be taken into consideration in the finishing surface of workpiece. One is the sufficient cutting force; the other is the relative moving speed between MAG and workpiece. The principle of step-motor rotating magnetic field is used to produce rotating magnetic field (RMF) in this paper. RMF brings MAG to rotate and keeps workpiece immovable. Meanwhile, the coins vibrate within a definite angle range and reciprocate in axial direction so as to process the outer cylindrical surfaces. Yoke iron is made of two halves so that the coins for rotating magnetic field will be keyed to some section of heavy crankshaft, thus realizing cylindrical surface finishing on the heavy crankshaft. MAG are of importance to MAF . Six performance indexes related to MAG are suggested by studying on process parameters.
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Sisi, Li, and Peng Yong. "Field Analysis on Magnetic Transmission Mechanism of Downhole Turbine Generator." Open Electrical & Electronic Engineering Journal 9, no. 1 (February 26, 2015): 43–52. http://dx.doi.org/10.2174/1874129001509010043.
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New downhole turbine generator can transmit the high speed rotation of the turbine to the rotor of the generator without contact by magnetic transmission mechanism to provide continuous power. Driving torque on magnetic transmission mechanism is a key parameter. This paper mainly studies the field on magnetic transmission mechanism of downhole turbine generator by using ANSYS software. The effects of thickness of permanent magnets, thickness of distance sleeve, the average radius of working field, air gaps and rotating speed on torque were quantitatively analyzed, and eddy current in distance sleeve with different structure parameters was also analyzed. Through the analysis, it can be shown that the influence of the eddy current in distance sleeve should be considered when designing the transmission mechanism to avoid reducing large torque. The size of magnetic transmission mechanism should be optimized for the design goal of large torque and low eddy current, avoiding overheating and making sure that the generator works normally.
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GELB, JAMES M., KAUNDINYA S. GOPINATH, and DALLAS C. KENNEDY. "RELATIVISTIC ELECTRONS IN A ROTATING SPHERICAL MAGNETIC DIPOLE: LOCALIZED THREE-DIMENSIONAL STATES." International Journal of Modern Physics D 08, no. 02 (April 1999): 251–70. http://dx.doi.org/10.1142/s0218271899000201.
Full textAbstract:
Paralleling a previous paper, we examine single- and many-body states of relativistic electrons in an intense, rotating magnetic dipole field. Single-body orbitals are derived semiclassically and then applied to the many-body case via the Thomas-Fermi approximation. The many-body case is reminiscent of the quantum Hall state. Electrons in a realistic neutron star crust are considered with both fixed density profiles and constant Fermi energy. In the first case, applicable to young neutron star crusts, the varying magnetic field and relativistic Coriolis correction lead to a varying Fermi energy and macroscopic currents. In the second, relevant to older crusts, the electron density is redistributed by the magnetic field.