Research on modeling and self-excited vibration mechanism in magnetic levitation-collision interface coupling system

The modeling and self-excited vibration mechanism in the magnetic levitation-collision interface coupling system are investigated.The effects of the control and interface parameters on the system's stability are analyzed.The frequency range of self-excited vibrations is investigated from the energy point of view.The phenomenon of self-excited vibrations is elaborated with the phase trajectory.The corresponding control strategies are briefly analyzed with respect to the vibration mechanism.The results show that when the levitation objects collide with the mechanical interface,the system's vibration frequency becomes larger with the decrease in the collision gap;when the vibration frequency exceeds the critical frequency,the electromagnetic system continues to provide energy to the system,and the collision interface continuously dissipates energy so that the system enters the self-excited vibration state.

Disturbance rejection tube model predictive levitation control of maglev trains

Magnetic levitation control technology plays a significant role in maglev trains.Designing a controller for the levitation system is challenging due to the strong nonlinearity,open-loop instability,and the need for fast response and security.In this paper,we propose a Disturbance-Observe-based Tube Model Predictive Levitation Control(DO-TMPLC)scheme combined with a feedback linearization strategy for the levitation system.The proposed strategy incorporates state constraints and control input constraints,i.e.,the air gap,the vertical velocity,and the current applied to the coil.A feedback linearization strategy is used to cancel the nonlinearity of the tracking error system.Then,a disturbance observer is implemented to actively compensate for disturbances while a TMPLC controller is employed to alleviate the remaining disturbances.Furthermore,we analyze the recursive feasibility and input-to-state stability of the closed-loop system.The simulation results indicate the efficacy of the proposed control strategy.

Levitation现象研究进展

漂浮(Levitation)现象可以定义为这样一种稳定情况,即在垂直振荡流体中颗粒的重力被完全抵消而仅在某一固定位置附近做振荡运动。作者分析了国内外研究现状,综述了以往学者对该现象进行的实验研究、理论分析以及数值模拟等工作。通过对Levitation现象研究文献的综述,总结了以往学者的一些研究成果,分析了他们所开展的研究之间的共性和分歧,在此基础上提出了目前对Levitation现象研究需解决的问题并对Levitation现象今后研究需要进一步解决的问题做了探讨。

THE ELECTROMAGNETIC FIELD CALCULATION AND ANALYSIS OF LEVITATION MELTING WITH COLD CRUCIBLE

In this paper, using the quasi-3D coupled current method, the influences of structure of cold crucible, the power frequency, the electricity property of melt, the coil position and current on the electromagnetic field (EMF) and the levitation characteristics in the melting processes are analyzed. It is shown that in the processes of levitation melting with cold crucible, the power frequency and cold crucible structure are the decisive factors for the ability of magnetic flux penetrating into cold crucible. The magnetic flux density in cold crucible is reduced as the increasing of power frequency, and this tendency becomes stronger when the power frequency is higher than 100kHz. The segmented structure of cold crucible can reduce the induction eddy in itself effectively, and the higher the power frequency is, the better the result is. So, a cold crucible can be segmented into 16-20 sectors for high frequency electromagnetic field and/or 8-12 sectors for lower frequency one. It is also shown that the levitation force of melting charge is related to coil current as a parabolic function.

ELECTROMAGNETIC MODEL OF LEVITATION MELTING WITH COLD CRUCIBLE

ＥＬＥＣＴＲＯＭＡＧＮＥＴＩＣＭＯＤＥＬＯＦＬＥＶＩＴＡＴＩＯＮＭＥＬＴＩＮＧＷＩＴＨＣＯＬＤＣＲＵＣＩＢＬＥＤｅｎｇＫａｎｇ；ＺｈｏｕＹｕｅｍｉｎｇ；ＲｅｎＺｈｏｎｇｍｉｎｇ；ＺｈｕＳｈｏｕｊｕｎ；ＷｅｉＪｉｈｅ；ＪｉａｎｇＧｕｏｃｈａｎｇ（Ｓｈａ...

A novel superconducting magnetic levitation method to support the laser fusion capsule by using permanent magnets

A novel magnetic levitation support method is proposed, which can relieve the perturbation caused by traditional support methods andprovide more accurate position control of the capsule. This method can keep the perfect symmetry of the octahedral spherical hohlraum and hasthe characteristics in stability, tunability and simplicity. It is also favorable that all the results, such as supporting forces acting on the super-conducting capsule, are calculated analytically, and numerical simulations are performed to verify these results. A typical realistic design isproposed and discussed in detail. The superconducting coating material is suggested, and the required superconducting properties are listed.Damped oscillation of the floating capsule in thin helium gas is discussed, and the restoring time is estimated.

NUMERICAL SIMULATION OF ALTERNATIVE HORIZONTAL LEVITATION ELECTROMAGNETIC CONTINUOUS CASTING（Ⅱ）

ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＡＬＴＥＲＮＡＴＩＶＥＨＯＲＩＺＯＮＴＡＬＬＥＶＩＴＡＴＩＯＮＥＬＥＣＴＲＯＭＡＧＮＥＴＩＣＣＯＮＴＩＮＵＯＵＳＣＡＳＴＩＮＧ（Ⅱ）￥ＺｈｕＳｈｏｕｊｕｎ；ＲｅｎＺｈｏｎｇｍｉｎｇ；ＤｅｎｇＫａｎｇ；Ｊｉａｎ...

Design and Development of Impeller Synergic Systems of Electromagnetic Type to Levitation/Suspension Flight of Symmetrical Bodies

Using certain models of twistor surfaces for fields of force and the mathematical relationships that lie among fields, lines, surfaces and flows of energy, it has been designed and developed a flight electromagnetic type system based on the synergic study of their electromagnetic field geodesics to generate vehicle levitation, suspension and movement without being in contact with the surface. The idea of such work is to obtain a new flight and impulse patent of an electromagnetic vehicle by principles of super-conduction and some laws of the current like Eddy currents and principles which are very similar to mechanics of sidereal objects like galaxies or stars under models of twistor surfaces. This vehicle will be controlled by one microchip that will be programmed by conscience operators algebra of electromagnetic type that leads to the flow of Eddy currents, the iso-rotations and suspension of the special geometrical characteristics vehicle, generating also on the vehicle structure certain “magnetic conscience” that provokes all movements like succeeding to the sidereal objects in the universe.

Computation and Analysis of Propellant and Levitation Forces of a Maglev System Using FEM Coupled to External Circuit Model

This paper studies the propellant and levitation forces of a prototype maglev system where the propellant forces are provided by a linear motor system. For this purpose, the mathematical model and method using finite element method coupled to external circuit model is developed. The details of the propellant and levitation forces for a prototype maglev system under different operating conditions are investigated, and some directions are given for practical engineering applications.

Research on magnetic levitation absolute vibration measurement method in vehicles

This paper presents a design for a magnetic levitation absolute- vibration test system which can be used by vehicles to measure the road surface roughness. The relationship between the vibration test system output voltage and measured speed of the object was obtained through testing,the power spectrum of the measured signal was obtained by virtual instrument analysis,the vibration waveforms of the vehicle over gentle and steep slopes were measured respectively and the road surface roughness was obtained by waveform analysis. Data was saved where the waveforms exceeded threshold. Finally,the steep slope was located using a GPS system. Experimental results show that the magnetic levitation absolute- vibration measurement method has characteristics of high sensitivity and a wide frequency range. This lays the foundation for research into multi- dimensional vibration measurements through magnetic levitation vibration test systems in vehicles.

Near-field acoustic levitation and applications to bearings:a critical review

The importance to industry of non-contact bearings is growing rapidly as the demand for highspeed and high-precision manufacturing equipment increases.As a recently developed non-contact technology,near-field acoustic levitation(NFAL)has drawn much attention for the advantages it offers,including no requirement for an external pressurized air supply,its compact structure,and its ability to adapt to its environment.In this paper,the working mechanism of NFAL is introduced in detail and compared to all existing non-contact technologies to demonstrate its versatility and potential for practical applications in industry.The fundamental theory of NFAL,including gas film lubrication theory and acoustic radiation pressure theory is presented.Then,the current stateof-the-art of the design and development of squeeze film air bearings based on NFAL is reviewed.Finally,future trends and obstacles to more widespread use are discussed.

STUDY ON DYNAMIC CHARACTERISTICS OF ACOUSTIC LEVITATION

ＳＴＵＤＹＯＮＤＹＮＡＭＩＣＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＡＣＯＵＳＴＩＣＬＥＶＩＴＡＴＩＯＮＧａｏＪｉａｎｒｏｎｇ（高建荣），ＣａｏＣｈｏｎｇｄｅ（曹崇德），ＷｅｉＢｉｎｇｂｏ（魏炳波）（ＬａｂｏｒａｔｏｒｙｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅ...

Maximization of Acoustic Levitating Force for a Single-Axis Acoustic Levitation System Using the Finite Element Method

We investigate single-axis acoustic levitation using standing waves to levitate particles freely in a medium bounded by a driver and a reflector. The acoustic pressure at the pressure antinode of the standing wave counteracts the downward gravitational force of the levitating object. The optimal relationship between the air gap and the driving frequency leads to resonance and hence maximization of the levitating force. Slight deviation from the exact resonance condition causes a reduction in acoustic pressure at the pressure antinodes. This results in a significant reduction of the levitating force. The driving frequency is kept constant while the air gap is varied for different conditions. The optimal air gap for maximizing the levitation force is studied for first three resonance modes. Furthermore, a levitating particle is introduced between the driver and the reflector. The dependence of the resonance condition on the size of the levitating particle as well as the position of the particle between the driver and the reflector has also been studied. As the size of the levitating particle increases, the resonance condition also gets modified. Finite element results show a good agreement with the validated results available in the literature. Furthermore, the finite element approach is also used to study the variation of acoustic pressure at the pressure antinode with respect to the size of the reflector. The optimum diameter of the reflector is calculated for maximizing the levitating force for three resonance modes.

Lateral magnetic stiffness under different parameters in a high-temperature superconductor levitation system

Magnetic stiffness determines the stability of a high-temperature superconductor(HTS)magnetic levitation system.The quantitative properties of the physical and geometrical parameters that affect the stiffness of HTS levitation systems should be identified for improving the stiffness by some effective methods.The magnetic stiffness is directly related to the first-order derivative of the magnetic force with respect to the corresponding displacement,which indicates that the effects of the parameters on the stiffness should be different from the relationships between the forces and the same parameters.In this paper,we study the influences of some physical and geometrical parameters,including the strength of the external magnetic field(B0)produced by a rectangular permanent magnet(PM),critical current density(Jc),the PM-to-HTS area ratio(α),and thickness ratio(β),on the lateral stiffness by using a numerical approach under zero-field cooling(ZFC)and field cooling(FC)conditions.In the first and second passes of the PM,the lateral stiffness at most of lateral positions essentially increases with B0 increasing and decreases withβincreasing in ZFC and FC.The largest lateral stiffness at every lateral position is almost produced by the minimum value of Jc,which is obviously different from the lateral force–Jc relation.Theα-dependent lateral stiffness changes with some parameters,which include the cooling conditions of the bulk HTS,lateral displacement,and movement history of the PM.These findings can provide some suggestions for improving the lateral stiffness of the HTS levitation system.

An improvement of frozen-image model and its application in a HTS levitation system

This paper mainly reports an improvement of frozen-image model which can qualitatively describe the influence of lateral moving speed on vertical force in a HTS levitation system under lateral movement with field-cooling condition.The model is improved by introducing a dipole which represents the influence of lateral moving speed and modifying the rule of diamagnetic dipole based on frozen-image model.The vertical and lateral forces that are obtained by this improved model agree with the previous measure...

Excessive levitation for the efficient loading of large-volume optical dipole traps

We study the excessive levitation effect in the magnetically levitated loading process of ultracold Cs atoms into a large-volume crossed optical dipole trap. We analyze the motion of atoms with a non-zero combined gravito-magnetic force during the loading, where the magnetically levitated force catches up with and surpasses the gravity. We present the theoretical variations of both acceleration and velocity with levitation time and magnetic field gradient. We measure the evolution of the number of trapped atoms with the excessive levitation time at different magnetic field gradients. The dependence of the number of atoms on the magnetic field gradient is also measured for different excessive levitation times.The theoretical analysis shows reasonable agreement with the experimental results. Our investigation illustrates that the excessive levitation can be used to reduce the heating effect of atoms in the magnetically levitated loading process, and to improve the loading rate of a large-volume optical dipole trap.

Homological Electromagnetism and Electromagnetic Demonstrations on the Existence of Superconducting Effects Necessaries to Magnetic Levitation/Suspension

Considering results obtained in magnetic levitation and suspension of the symmetrical bodies are designed and developed several experiments of the electromagnetism that demonstrate the effects of a superconductor necessary to the magnetic levitation/suspension. This generates bases to the development of a reactor to impulse and anti-gravitational magnetic displacement of a vehicle considering the production and transference of Eddy currents on their structure to microscopic level and the effect of auto-levitation/auto-suspension that is obtained with the iso-rotations of the impulse magnetic ring of the proper vehicle.

Real Magnetic Charges in the Substance, Ferrogravitation and Technical Levitation

Experimental and theoretical investigations by author of the present article (period: 1968-2013) have shown that the magnetic spinor particles (magnetic charges) are real structural components of atoms and substance and are immediate sources of all magnetic fields in Nature. Joint orbital currents of electric and magnetic charges within atomic shells are the natural sources of gravitational field which is a vortex electromagnetic field. The vector character of the elementary gravitational field is similar to the vortex magnetic field that allows entering in the submission of such fundamental states of the gravitational field, as a paragravitation and ferrogravitation. Physical masses (atoms, nucleons, substance, etc.), which emit ferrogravitational field are repelled off from sources paragravitational field, for example, from Earth. It is a manifestation of the effect of levitation, which was discovered by the author of this article. Technical forces levitation, that induced by technical ferrogravitational fields, could be used in transport, lifting and space technology, power engineering and many other areas of human activity. The main reasons that real magnetic charges are “buried alive” in modern theoretical notions are as physics their of confinement in the structures of atoms and substance which are radically different from the confinement of electrons so and fallacious electromagnetic concept Maxwell in which the magnetic field is by mistake deprived of its own source of the magnetic pole or of the magnetic charge.

Real Magnetic Poles (Magnetic Charges) in the Physics of Magnetism, Gravitation and Levitation

Experiments executed by author of the present article (period 1968-1992) showed that the magnetic spinorial particles (magnetic charges) are real structural components of atoms and substance and are immediate sources of all magnetic fields in Nature. Joint orbital currents of electric and magnetic charges within atomic shells are the natural sources of gravitational field which is a vortical electromagnetic field. The vector nature of the gravitational field, in essence, is analogous to the vortical magnetic field that allows entering in the physical representations of such States of the gravitational field as paragravitation and ferrogravitation. Physical masses (atoms, substance, etc.), which emit ferrogravitational field, are repelled by sources paragravitational field, for example, from Earth. It is a manifestation of the effect of levitation, which was discovered by the author of this article. The forces of the technical levitation, which are formed by technical ferrogravitational fields, can be used in transport, lifting and space technology, energy and many other areas of human activity. The main reason that the real magnetic charges were “buried alive” in modern theoretical physics is the conditions of their confinement in the structures of atoms and substance, which is radically different from the confinement of electrons. Very negative role is played here by erroneous electromagnetic concept Maxwell, in which the magnetic field was officially deprived of their own source: magnetic pole or magnetic charge.

Magnetic Levitation of Diamond Modified with Manganese and Bismuth

Operating diamond grits to produce a precise grind tool is need. In order to lift up a diamond grit by magnetic force, the magnetic flux was estimated to be 100 μT/g. Diamond (110) surface was modified with manganese powder at 450°C (720 K) then with bismuth powder at 270°C (540 K) due to its low melting temperature. Manganese carbides were formed on the diamond surface which was confirmed by an X-ray diffraction. A magnet that exhibits ferrimagnetism was formed on the surface, it had a spontaneous magnetism. We conducted to form six small disk magnets at hexagonal apex positions on the diamond (110) by using gold film mask. The magnetic flux measured at the center of the hexagon magnets on was 232 μT at room temperature, and the surface modified diamond grid could be lifted up in the magnetic field between two solenoid coils.