Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation...Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation,leading to brain lesions and cognitive impairment,numerous studies have aimed to reduce Aβaggregation and slow AD progression.The diphenylalanine(FF)sequence is critical for amyloid aggregation,and magnetic fields can affect peptide alignment due to the diamagnetic anisotropy of aromatic rings.In this study,we examined the effects of a moderate-intensity rotating magnetic field(RMF)on Aβaggregation and AD pathogenesis.Results indicated that the RMF directly inhibited Aβamyloid fibril formation and reduced Aβ-induced cytotoxicity in neural cells in vitro.Using the AD mouse model APP/PS1,RMF restored motor abilities to healthy control levels and significantly alleviated cognitive impairments,including exploration and spatial and non-spatial memory abilities.Tissue examinations demonstrated that RMF reduced amyloid plaque accumulation,attenuated microglial activation,and reduced oxidative stress in the APP/PS1 mouse brain.These findings suggest that RMF holds considerable potential as a non-invasive,high-penetration physical approach for AD treatment.展开更多
Currently,three types of superconducting quadrupole magnets are used in particle accelerators:cos 2θ,CCT,and serpentine.However,all three coil configurations have complex spatial geometries,which make magnet manufact...Currently,three types of superconducting quadrupole magnets are used in particle accelerators:cos 2θ,CCT,and serpentine.However,all three coil configurations have complex spatial geometries,which make magnet manufacturing and strain-sensitive superconductor applications difficult.Compared with the three existing quadrupole coils,the racetrack quadrupole coil has a simple shape and manufacturing process,but there have been few theoretical studies.In this paper,the two-dimensional and three-dimensional analytical expressions for the magnetic field in coil-dominated racetrack superconducting quadrupole magnets are presented.The analytical expressions of the field harmonics and gradient are fully resolved and depend only on the geometric parameters of the coil and current density.Then,a genetic algorithm is applied to obtain a solution for the coil geometry parameters with field harmonics on the order of 10^(-4).Finally,considering the practical engineering needs of the accelerator interaction region,electromagnetic design examples of racetrack quadrupole magnets with high gradients,large apertures,and small apertures are described,and the application prospects of racetrack quadrupole coils are analyzed.展开更多
The Al-5Cu alloys were prepared by different treatment methods,including adding a refiner Al-5Ti-1B,exerting a rotating magnetic field(RMF),and compound treatment of both refiner and RMF.The effects of treatment metho...The Al-5Cu alloys were prepared by different treatment methods,including adding a refiner Al-5Ti-1B,exerting a rotating magnetic field(RMF),and compound treatment of both refiner and RMF.The effects of treatment methods on the microstructure,properties,and solid solubility of the Al-5Cu alloy were investigated.The optimal magnetic field parameters and addition amount of refiner were confirmed by experiment.Results show that either RMF or adding refiner Al-5Ti-1B alone can refine the grain size,and the refining effect can be further improved by a compound refining treatment with optimized magnetic field parameters(120 A current and 8 Hz frequency) and 1.0wt.% Al-5Ti-1B refiner(RMF*+Al-5Ti-1B*).The average grain size is decreased to 68.1 μm,which is 60.8%,21.1%,and 83.5% lower than that of the alloy treated by the optimized rotating magnetic field,the Al-5Ti-1B refiner,and the alloy without any treatment,respectively.The tensile strength and elongation of the alloy reach 232.5 MPa and 18.6%,respectively,which are obviously higher than those of the alloys treated by rotating magnetic field,Al-5Ti-1B refiner,and the alloy without any treatment,respectively.Additionally,the solid solubility of the alloy is also obviously improved compared to the alloys treated by other methods.展开更多
With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis metho...With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis method for studying the new motor topology.This paper introduces the principle of magnetic field modulation.And the research on high torque density in recent years is reviewed from the perspective of magnetic field modulation,including permanent magnet vernier machine(PMVM),flux reverse machine(FRM),flux switching machine(FSM),dual permanent magnet(DPM)machine,and DC biased machine.The principle of magnetic field modulation makes it possible to propose higher torque density topologies in the future.展开更多
Today, the origin of the magnetic field of stars and planets is explained by the dynamo effect. Since Cowling’s anti-dynamo theorem has forbidden a purely axisymmetric dynamo, scientists are all convinced today that ...Today, the origin of the magnetic field of stars and planets is explained by the dynamo effect. Since Cowling’s anti-dynamo theorem has forbidden a purely axisymmetric dynamo, scientists are all convinced today that the fluid flow in the core of a star cannot be laminar, so it is turbulent. However, we will see in this study that the configuration in which the conductive fluid contained in the core of a star is in rapid rotation around an axis of symmetry is the one that best explains the origin of the magnetic field of stars and planets. It also explains why certain types of stars have very intense magnetic fields. Indeed, we will show here that the magnetic field of stars and planets is created by the electric current generated by the rotational movement of charged fluid particles as in an electromagnet. The lines of this magnetic field are channelled by the solid paramagnetic seed which plays the role of magnetic core in the cores of planets and stars. The seed is composed mainly of Iron and Nickel on the planets and of solid helium-3 in the stars. In this work, we will use this model of rapidly rotating fluids to introduce a new way to ionize a neutral gas and maintain it in a plasma state for indefinitely large time scales, to present a new technique for generating very intense magnetic fields, to establish a new magnetic nucleation process and to propose a new type of nuclear fusion reactor in which the plasma is perpetually rapidly rotating.展开更多
From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart'...From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk,but also for that of several rectangular permanent magnet bulks. By using this expression,the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets,in order to describe its distribution,two quantities,one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field,were defined. Furthermore,the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.展开更多
We study the Heisenberg model under the influence of a rotating magnetic field. By using a time-dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no...We study the Heisenberg model under the influence of a rotating magnetic field. By using a time-dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no chronological product. The spin vectors (mean values of the spin operators) are obtained as explicit functions of time in the most general case. A series of cyclic solutions are presented. The nonadiabatic geometric phases of these cyclic solutions are calculated, and are expressed in terms of the solid angle subtended by the closed trace of the total spin vector, as well as in terms of those of the individual spins.展开更多
In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distributi...In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM,which were sectional calculation(SC)method and three-dimensional finite element(3-D FE)method.On this basis,the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model.Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor,and the amplitude regularity of the axial magnetic force is affected by the d-axis current.A prototype machine is fabricated and tested,in order to validate the design theory.展开更多
Aiming at obtaining high power density of surface-mounted and interior permanent magnet synchronous motor(SIPMSM),it is important to accurately calculate the temperature field distribution of SIPMSM,and a magnetic-the...Aiming at obtaining high power density of surface-mounted and interior permanent magnet synchronous motor(SIPMSM),it is important to accurately calculate the temperature field distribution of SIPMSM,and a magnetic-thermal coupling method is proposed.The magnetic-thermal coupling mechanism is analyzed.The thermal network model and finite element model are built by this method,respectively.The effects of power frequency on iron losses and temperature fields are analyzed by the magnetic-thermal coupling finite element model under the condition of rated load,and the relationship between the load and temperature field is researched under the condition of the synchronous speed.In addition,the equivalent thermal network model is used to verify the magnetic-thermal coupling method.Then the temperatures of various nodes are obtained.The results show that there are advantages in both computational efficiency and accuracy for the proposed coupling method,which can be applied to other permanent magnet motors with complex structures.展开更多
Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kin...Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kinds of electromagnetic filed can enforce the columnar-equiaxed transition, the driving one decrease the tendency of porosity occurring due to the increase in the bulk liquid pressure. Stirring with braking electromagnetic field produces the mixture of outer fine grains and inner coarse grains in the casting, this is analyzed to be contributed to the differences both in electric conductivity and density between the crystal and the melt, as well as skin effects.展开更多
A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field (RMF). The driven current can reverse the original equil...A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field (RMF). The driven current can reverse the original equilibrium field and generate a field-reversed-configuration. In a conventional rotamak, a toroidal field (TF) is not necessary for the RMF to drive plasma current, but it was found that the present of an additional TF can influence the RMF current drive. In this paper the effect of TF on the RMF current drive in a rotamak are investigated in some detail. The experimental results show that addition of TF increases the RMF driven current greatly and enhances the RMF penetration dramatically. Without TF, the RMF can only penetrate into plasma in the edge region. When a TF is added, the RMF can reach almost the whole plasma region. This is an optimal strength of toroidal magnetic field for getting maximum plasma current when Bv and radio frequency generator power are fixed. Besides driving current, the RMF generates high harmonic fields in rotamak plasma. The effect of TF on the harmonic field spectra are also reported.展开更多
The three-dimensional magnetic field of a permanent permanent (PM) disc-type generator is analyzed by the scalar potential method. In the analysis the permanent magnets are taken as magnetic charges. Hexahedron elemen...The three-dimensional magnetic field of a permanent permanent (PM) disc-type generator is analyzed by the scalar potential method. In the analysis the permanent magnets are taken as magnetic charges. Hexahedron element meshes are automatically generated by a prc-proccssing program developed by the authors. The flux densily is computed by a 3D scalar potential method program. Based on the linite elcment analysis the induced emf, current, armaturc reaction effects and electromagnetic torque of the disc machine are all calculated.展开更多
The equation of motion of an object moving in a frictionless horizontal rotating frame is somewhat comparable to the one describing the motion of a point-like charged particle projected in a magnetic field. We show th...The equation of motion of an object moving in a frictionless horizontal rotating frame is somewhat comparable to the one describing the motion of a point-like charged particle projected in a magnetic field. We show that the impact of angular velocity in the former is equivalent to the impact of the magnetic field in the latter. We consider scenarios conducive to comparable trajectories for these two distinct areas of physics. We extend the analysis considering two separate routes. For the rotating frame we investigate the impact of friction and for the magnetic field the effect of field in-homogeneities. We utilize Mathematica [1] throughout, most notably for solving coupled partial differential equations.展开更多
The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to th...The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to the first orderin the uniform angular velocity.The results show that compared with the corresponding non-rotating static sphericalsymmetric neutron star with a weaker magnetic field,a fast rotating neutron star(millisecond pulsar)with a strongermagnetic field has a relative smaller moment of inertia and radius of gyration.展开更多
The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
The present paper describes an investigation conducted on metal detectors installed with a scanning probe.The authors applied a rotating magnetic field probe to metal detection.The rotating magnetic field probe is com...The present paper describes an investigation conducted on metal detectors installed with a scanning probe.The authors applied a rotating magnetic field probe to metal detection.The rotating magnetic field probe is comprised of two vertically placed rectangular exciting coils and a circular detecting coil.The experimental results confirmed that the probe can detect metal objects and provide more information about their shape,direction,and electromagnetic characteristics than conventional metal detector probes.A two-dimensional signal display shows a low-resolution image of the metal object and the signal phase indicates the object’s direction and electromagnetic characteristics.The experimental results show that excellent reconstruction of the surface shapes of metal objects can be obtained for both magnetic and nonmagnetic metals under present conditions.There is also the potential for the approximate shape of a metal object to be estimated from the reconstructed image.展开更多
Employing Biot’s theory of wave propagation in liquid saturated porous media,the effect of rotation and magnetic field on wave propagation in a hollow poroelastic circular of infinite extent is investigated.An exact ...Employing Biot’s theory of wave propagation in liquid saturated porous media,the effect of rotation and magnetic field on wave propagation in a hollow poroelastic circular of infinite extent is investigated.An exact closed form solution is presented.General frequency equations for propagation of poroelastic cylinder are obtained when the boundaries are stress free.The frequencies are calculated for poroelastic cylinder for different values of magnetic field and rotation.Numerical results are given and illustrated graphically.The results indicate that the effect of rotation,and magnetic field are very pronounced.Such a model would be useful in large-scale parametric studies of mechanical response.展开更多
With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are inve...With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are investigated with the Maxwell stress tensor method. Accurate results can easily be achieved using the proposed method without using the tedious finite element analysis (FEA). In this paper, the electromagnetic torque of a surface mounted PM motor with two phases energized is decomposed into four torque components. This technique is useful not only for the design and optimization of the permanent magnet motor, but also for the choice of control strategy.展开更多
This paper analyzes the structure and transmission principles of a modulation permanent magnet gear transmission. Its 3D data model is built based on the known optimized parameters from research team. Its structure of...This paper analyzes the structure and transmission principles of a modulation permanent magnet gear transmission. Its 3D data model is built based on the known optimized parameters from research team. Its structure of the harmonic response is analyzed and discussed under the software ANSYS. The displacement response and the initial 6 order response frequency and phase angle are obtained. The change rule of these responses is known under the forced vibration.展开更多
Because of its simple structure,large torque and high efficiency,permanent magnet synchronous motor of low speed and high torque is widely adopted in many fields.In this paper,a 394.5k W mining low-speed high-torque p...Because of its simple structure,large torque and high efficiency,permanent magnet synchronous motor of low speed and high torque is widely adopted in many fields.In this paper,a 394.5k W mining low-speed high-torque permanent magnet synchronous motor(LSHTPMSM)is regarded as the study object.According to the physical model,a three-dimensional equivalent heat transfer temperature field calculation model of the motor is built to simulate the temperature distribution of the motor under rated conditions.In terms of the serious issue of stator winding temperature increase of permanent magnet synchronous motor of low speed and high torque,the heat conduction optimization of the end of the stator winding is studied,which enhances the heat dissipation effect of the stator end winding,effectively reduces its temperature increase and temperature gradient with the winding in the slot,and improves the practical efficiency and service life of the motor.Finally,the motor temperature rise test platform is constructed for the verification of the feasibility of the optimization scheme,which provides a reference direction for the heat dissipation optimization of permanent magnet synchronous motor of low speed and high torque.展开更多
基金National Key R&D Program of China(2023YFB3507004)National Natural Science Foundation of China(U21A20148)+2 种基金International Partnership Program of Chinese Academy of Sciences(116134KYSB20210052)Heye Health Technology Chong Ming Project(HYCMP2021010)CASHIPS Director’s Fund(BJPY2021A06)。
文摘Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation,leading to brain lesions and cognitive impairment,numerous studies have aimed to reduce Aβaggregation and slow AD progression.The diphenylalanine(FF)sequence is critical for amyloid aggregation,and magnetic fields can affect peptide alignment due to the diamagnetic anisotropy of aromatic rings.In this study,we examined the effects of a moderate-intensity rotating magnetic field(RMF)on Aβaggregation and AD pathogenesis.Results indicated that the RMF directly inhibited Aβamyloid fibril formation and reduced Aβ-induced cytotoxicity in neural cells in vitro.Using the AD mouse model APP/PS1,RMF restored motor abilities to healthy control levels and significantly alleviated cognitive impairments,including exploration and spatial and non-spatial memory abilities.Tissue examinations demonstrated that RMF reduced amyloid plaque accumulation,attenuated microglial activation,and reduced oxidative stress in the APP/PS1 mouse brain.These findings suggest that RMF holds considerable potential as a non-invasive,high-penetration physical approach for AD treatment.
基金supported in part by the National Key Research and Development Program of China(No.2022YFA1603402)in part by the National Natural Science Foundation of China(No.11875272)。
文摘Currently,three types of superconducting quadrupole magnets are used in particle accelerators:cos 2θ,CCT,and serpentine.However,all three coil configurations have complex spatial geometries,which make magnet manufacturing and strain-sensitive superconductor applications difficult.Compared with the three existing quadrupole coils,the racetrack quadrupole coil has a simple shape and manufacturing process,but there have been few theoretical studies.In this paper,the two-dimensional and three-dimensional analytical expressions for the magnetic field in coil-dominated racetrack superconducting quadrupole magnets are presented.The analytical expressions of the field harmonics and gradient are fully resolved and depend only on the geometric parameters of the coil and current density.Then,a genetic algorithm is applied to obtain a solution for the coil geometry parameters with field harmonics on the order of 10^(-4).Finally,considering the practical engineering needs of the accelerator interaction region,electromagnetic design examples of racetrack quadrupole magnets with high gradients,large apertures,and small apertures are described,and the application prospects of racetrack quadrupole coils are analyzed.
文摘The Al-5Cu alloys were prepared by different treatment methods,including adding a refiner Al-5Ti-1B,exerting a rotating magnetic field(RMF),and compound treatment of both refiner and RMF.The effects of treatment methods on the microstructure,properties,and solid solubility of the Al-5Cu alloy were investigated.The optimal magnetic field parameters and addition amount of refiner were confirmed by experiment.Results show that either RMF or adding refiner Al-5Ti-1B alone can refine the grain size,and the refining effect can be further improved by a compound refining treatment with optimized magnetic field parameters(120 A current and 8 Hz frequency) and 1.0wt.% Al-5Ti-1B refiner(RMF*+Al-5Ti-1B*).The average grain size is decreased to 68.1 μm,which is 60.8%,21.1%,and 83.5% lower than that of the alloy treated by the optimized rotating magnetic field,the Al-5Ti-1B refiner,and the alloy without any treatment,respectively.The tensile strength and elongation of the alloy reach 232.5 MPa and 18.6%,respectively,which are obviously higher than those of the alloys treated by rotating magnetic field,Al-5Ti-1B refiner,and the alloy without any treatment,respectively.Additionally,the solid solubility of the alloy is also obviously improved compared to the alloys treated by other methods.
基金supported in part by the National Natural Science Foundation of China(NSFC)under Project No.51737010the National Key R&D Program of China under Grant 2020YFA0710500。
文摘With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis method for studying the new motor topology.This paper introduces the principle of magnetic field modulation.And the research on high torque density in recent years is reviewed from the perspective of magnetic field modulation,including permanent magnet vernier machine(PMVM),flux reverse machine(FRM),flux switching machine(FSM),dual permanent magnet(DPM)machine,and DC biased machine.The principle of magnetic field modulation makes it possible to propose higher torque density topologies in the future.
文摘Today, the origin of the magnetic field of stars and planets is explained by the dynamo effect. Since Cowling’s anti-dynamo theorem has forbidden a purely axisymmetric dynamo, scientists are all convinced today that the fluid flow in the core of a star cannot be laminar, so it is turbulent. However, we will see in this study that the configuration in which the conductive fluid contained in the core of a star is in rapid rotation around an axis of symmetry is the one that best explains the origin of the magnetic field of stars and planets. It also explains why certain types of stars have very intense magnetic fields. Indeed, we will show here that the magnetic field of stars and planets is created by the electric current generated by the rotational movement of charged fluid particles as in an electromagnet. The lines of this magnetic field are channelled by the solid paramagnetic seed which plays the role of magnetic core in the cores of planets and stars. The seed is composed mainly of Iron and Nickel on the planets and of solid helium-3 in the stars. In this work, we will use this model of rapidly rotating fluids to introduce a new way to ionize a neutral gas and maintain it in a plasma state for indefinitely large time scales, to present a new technique for generating very intense magnetic fields, to establish a new magnetic nucleation process and to propose a new type of nuclear fusion reactor in which the plasma is perpetually rapidly rotating.
文摘From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk,but also for that of several rectangular permanent magnet bulks. By using this expression,the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets,in order to describe its distribution,two quantities,one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field,were defined. Furthermore,the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.
文摘We study the Heisenberg model under the influence of a rotating magnetic field. By using a time-dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no chronological product. The spin vectors (mean values of the spin operators) are obtained as explicit functions of time in the most general case. A series of cyclic solutions are presented. The nonadiabatic geometric phases of these cyclic solutions are calculated, and are expressed in terms of the solid angle subtended by the closed trace of the total spin vector, as well as in terms of those of the individual spins.
基金This work was supported by the National Natural Science Foundation,China under Grant 5173000400.
文摘In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM,which were sectional calculation(SC)method and three-dimensional finite element(3-D FE)method.On this basis,the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model.Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor,and the amplitude regularity of the axial magnetic force is affected by the d-axis current.A prototype machine is fabricated and tested,in order to validate the design theory.
基金This work was supported by Natural Science Foundation of China(Item number:51777060,U1361109)Natural Science Foundation of Henan province(Item number:162300410117)the he innovative research team plan of Henan Polytechnic University(Item number:T2015-2).
文摘Aiming at obtaining high power density of surface-mounted and interior permanent magnet synchronous motor(SIPMSM),it is important to accurately calculate the temperature field distribution of SIPMSM,and a magnetic-thermal coupling method is proposed.The magnetic-thermal coupling mechanism is analyzed.The thermal network model and finite element model are built by this method,respectively.The effects of power frequency on iron losses and temperature fields are analyzed by the magnetic-thermal coupling finite element model under the condition of rated load,and the relationship between the load and temperature field is researched under the condition of the synchronous speed.In addition,the equivalent thermal network model is used to verify the magnetic-thermal coupling method.Then the temperatures of various nodes are obtained.The results show that there are advantages in both computational efficiency and accuracy for the proposed coupling method,which can be applied to other permanent magnet motors with complex structures.
文摘Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kinds of electromagnetic filed can enforce the columnar-equiaxed transition, the driving one decrease the tendency of porosity occurring due to the increase in the bulk liquid pressure. Stirring with braking electromagnetic field produces the mixture of outer fine grains and inner coarse grains in the casting, this is analyzed to be contributed to the differences both in electric conductivity and density between the crystal and the melt, as well as skin effects.
基金Project supported by the National Natural Science Foundation of China (Grant No 105750215) and by US D0E (Grant No DE-FG03-97ER54416).
文摘A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field (RMF). The driven current can reverse the original equilibrium field and generate a field-reversed-configuration. In a conventional rotamak, a toroidal field (TF) is not necessary for the RMF to drive plasma current, but it was found that the present of an additional TF can influence the RMF current drive. In this paper the effect of TF on the RMF current drive in a rotamak are investigated in some detail. The experimental results show that addition of TF increases the RMF driven current greatly and enhances the RMF penetration dramatically. Without TF, the RMF can only penetrate into plasma in the edge region. When a TF is added, the RMF can reach almost the whole plasma region. This is an optimal strength of toroidal magnetic field for getting maximum plasma current when Bv and radio frequency generator power are fixed. Besides driving current, the RMF generates high harmonic fields in rotamak plasma. The effect of TF on the harmonic field spectra are also reported.
文摘The three-dimensional magnetic field of a permanent permanent (PM) disc-type generator is analyzed by the scalar potential method. In the analysis the permanent magnets are taken as magnetic charges. Hexahedron element meshes are automatically generated by a prc-proccssing program developed by the authors. The flux densily is computed by a 3D scalar potential method program. Based on the linite elcment analysis the induced emf, current, armaturc reaction effects and electromagnetic torque of the disc machine are all calculated.
文摘The equation of motion of an object moving in a frictionless horizontal rotating frame is somewhat comparable to the one describing the motion of a point-like charged particle projected in a magnetic field. We show that the impact of angular velocity in the former is equivalent to the impact of the magnetic field in the latter. We consider scenarios conducive to comparable trajectories for these two distinct areas of physics. We extend the analysis considering two separate routes. For the rotating frame we investigate the impact of friction and for the magnetic field the effect of field in-homogeneities. We utilize Mathematica [1] throughout, most notably for solving coupled partial differential equations.
基金National Natural Science Foundation of China under Grant Nos.10647116 and 10575140the China Postdoctoral Science Foundation under Grant No.2005037175
文摘The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to the first orderin the uniform angular velocity.The results show that compared with the corresponding non-rotating static sphericalsymmetric neutron star with a weaker magnetic field,a fast rotating neutron star(millisecond pulsar)with a strongermagnetic field has a relative smaller moment of inertia and radius of gyration.
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
文摘The present paper describes an investigation conducted on metal detectors installed with a scanning probe.The authors applied a rotating magnetic field probe to metal detection.The rotating magnetic field probe is comprised of two vertically placed rectangular exciting coils and a circular detecting coil.The experimental results confirmed that the probe can detect metal objects and provide more information about their shape,direction,and electromagnetic characteristics than conventional metal detector probes.A two-dimensional signal display shows a low-resolution image of the metal object and the signal phase indicates the object’s direction and electromagnetic characteristics.The experimental results show that excellent reconstruction of the surface shapes of metal objects can be obtained for both magnetic and nonmagnetic metals under present conditions.There is also the potential for the approximate shape of a metal object to be estimated from the reconstructed image.
文摘Employing Biot’s theory of wave propagation in liquid saturated porous media,the effect of rotation and magnetic field on wave propagation in a hollow poroelastic circular of infinite extent is investigated.An exact closed form solution is presented.General frequency equations for propagation of poroelastic cylinder are obtained when the boundaries are stress free.The frequencies are calculated for poroelastic cylinder for different values of magnetic field and rotation.Numerical results are given and illustrated graphically.The results indicate that the effect of rotation,and magnetic field are very pronounced.Such a model would be useful in large-scale parametric studies of mechanical response.
基金Project supported by the Science Foundation of Shanghai Municipal Commission of Education (Grant No.04AB30)
文摘With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are investigated with the Maxwell stress tensor method. Accurate results can easily be achieved using the proposed method without using the tedious finite element analysis (FEA). In this paper, the electromagnetic torque of a surface mounted PM motor with two phases energized is decomposed into four torque components. This technique is useful not only for the design and optimization of the permanent magnet motor, but also for the choice of control strategy.
文摘This paper analyzes the structure and transmission principles of a modulation permanent magnet gear transmission. Its 3D data model is built based on the known optimized parameters from research team. Its structure of the harmonic response is analyzed and discussed under the software ANSYS. The displacement response and the initial 6 order response frequency and phase angle are obtained. The change rule of these responses is known under the forced vibration.
基金supported by the National Natural Science Funds of China No.51907129Technology program of Liaoning province No.2021-MS-236。
文摘Because of its simple structure,large torque and high efficiency,permanent magnet synchronous motor of low speed and high torque is widely adopted in many fields.In this paper,a 394.5k W mining low-speed high-torque permanent magnet synchronous motor(LSHTPMSM)is regarded as the study object.According to the physical model,a three-dimensional equivalent heat transfer temperature field calculation model of the motor is built to simulate the temperature distribution of the motor under rated conditions.In terms of the serious issue of stator winding temperature increase of permanent magnet synchronous motor of low speed and high torque,the heat conduction optimization of the end of the stator winding is studied,which enhances the heat dissipation effect of the stator end winding,effectively reduces its temperature increase and temperature gradient with the winding in the slot,and improves the practical efficiency and service life of the motor.Finally,the motor temperature rise test platform is constructed for the verification of the feasibility of the optimization scheme,which provides a reference direction for the heat dissipation optimization of permanent magnet synchronous motor of low speed and high torque.