The influence of the magnetization of a soft magnetic sphere on the surrounding magnetic field is measured and characterized.The interaction force between two soft magnetic particles is directly measured using an ultr...The influence of the magnetization of a soft magnetic sphere on the surrounding magnetic field is measured and characterized.The interaction force between two soft magnetic particles is directly measured using an ultra precision load sensor in uniform and non-uniform magnetic fields. The interaction force largely follows an inverse fourth power law as a function of separation distance between particle centers. At small distances,the effect of magnetization of one particle on the magnetization of its adjacent particle causes the attractive(repulsive) force to be larger(smaller) than that predicted by the inverse fourth power law.The theoretical prediction based on a modified dipole model,that takes into account the coupling effect of the magnetization among soft magnetic particles,gives excellent agreement with the measured force in a uniform magnetic field.The interaction force under a non-uniform applied magnetic field can be reasonably predicted using the dipole-dipole interaction model when the local magnetic field is used to determine the magnetization.展开更多
This paper presents a comparative investigation into unbalanced magnetic force(UMF)of asymmetric permanent magnet machines without rotor eccentricities,particularly focusing on the difference between internal-and exte...This paper presents a comparative investigation into unbalanced magnetic force(UMF)of asymmetric permanent magnet machines without rotor eccentricities,particularly focusing on the difference between internal-and external-rotor topologies.The asymmetric field distribution results in radial and tangential asymmetric force waves.Although the radial and tangential stresses are in different direction,the UMF components they produce are nearly aligned.The UMF from asymmetric radial force wave can be additive or subtractive to that from asymmetric tangential force wave.Investigation shows that for the same pole slot number combination,if the UMFs due to radial and tangential force waves are additive in internal rotor machine,they are subtractive in the external rotor counterpart,and vice versa.Investigation reveals a general rule determining whether additive or cancelling:for a UMF produced by any two field harmonics,they are additive if the higher order is produced by the outer part outside the airgap,but cancelling if the higher order is produced by the inner part.Therefore,for a machine with pole number 2p=3k+1,they are additive if it is an external-rotor machine,but otherwise subtractive.On the other hand,for a machine with pole number 2p=3k-1,they are subtractive if it is an external-rotor machine,but otherwise additive.For the UMF due to armature reaction only,they are subtractive for external-rotor machines,but otherwise additive.The investigation is carried out by an analytical model and validated by finite element analysis.展开更多
In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare co...In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare comprehensively considered, and the governing equations are solved bysimplifying the boundary conditions. The axial magnetization of the sectorshapedpermanent magnets is accurately described in an algebraic form bythe parameters, which makes the physical meaning more explicit than thepurely mathematical expression in general series forms. The parameters of theBessel function are determined simply and the magnetic field distribution ofpermanent magnets and the air-gap is solved. Furthermore, the field solutionsare completely analytical, which provides convenience and satisfactoryaccuracy for modeling a series of electromagnetic performance parameters,such as the axial electromagnetic force density, axial electromagnetic force,and electromagnetic torque. The correctness and accuracy of the analyticalmodels are fully verified by three-dimensional finite element simulations and a15 kW prototype and the results of calculations, simulations, and experimentsunder three methods are highly consistent. The influence of several designparameters on magnetic field distribution and performance is studied and discussed.The results indicate that the modeling method proposed in this papercan calculate the magnetic field distribution and performance accurately andrapidly, which affords an important reference for the design and optimizationof axial-flux permanent magnet drivers.展开更多
For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic fi...For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities(H),leading to the deterioration of the fluidization quality.The critical intensity(H_(ms))above which such segregation commences varies with the gas velocity(U_g).This work focuses on establishing a segregation model to theoretically derive the H_(ms)–U_g relationship.In a magnetic field,the magnetizable particles form agglomerates.The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles.Consequently,the segregation model was established in two steps:first,the size of agglomerates(d_A)was calculated by the force balance model;then,the H_(ms)–U_g relationship was obtained by substituting the expression of d_Ainto the basic size segregation model for binary mixtures.As per the force balance model,the cohesive and collision forces were 1_2 orders of magnitude greater than the other forces exerted on the agglomerates.Therefore,the balance between these two forces largely determined d_A.The calculated d_A increased with increasing H and decreasing U_g,agreeing qualitatively with the experimental observation.The calculated H_(ms)–U_ g relationship agreed reasonably with the experimental data,indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.展开更多
After measuring arc electrical current density distribution in gas tungsten arc welding(GTAW) with a probe method, the new expression of body force and model of LD10CS aluminum alloy weld pool are put forward for the ...After measuring arc electrical current density distribution in gas tungsten arc welding(GTAW) with a probe method, the new expression of body force and model of LD10CS aluminum alloy weld pool are put forward for the first time in GTAW with additional longitudinal magnetic field controlling. The influence of additional longitudinal magnetic field on body force is discussed by electromagnetic principle. This study provides the basis to study fluid flow of the weld pools and arc welding technique with electromagnetic controlling. [展开更多
The phenomenon of electrical attraction and repulsion between charged particles is well known, and described mathematically by Coulomb’s Law, yet until now there has been no explanation for why this occurs. There has...The phenomenon of electrical attraction and repulsion between charged particles is well known, and described mathematically by Coulomb’s Law, yet until now there has been no explanation for why this occurs. There has been no mechanistic explanation that reveals what causes the charged particles to accelerate, either towards or away from each other. This paper gives a detailed explanation of the phenomena of electrical attraction and repulsion based on my previous work that determined the exact wave-function solutions for both the Electron and the Positron. It is revealed that the effects are caused by wave interactions between the wave functions that result in Electromagnetic reflections of parts of the particle’s wave functions, causing a change in their momenta.展开更多
Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of wh...Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field(ExMF). Two types of Ex MFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet(PM) and another generated by an electromagnet(EM) on the order of 2 T. Two forces, including the magnetostatic force between the Ex MF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition,Ex MFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate Ex MF. However, the magnetostatic force will account for a high proportion of the measured force,thus inhibiting the normal LFV operation, if the Ex MF is too high.展开更多
The atomic force microscope(AFM)can measure nanoscale morphology and mechanical properties and has a wide range of applications.The traditional method for measuring the mechanical properties of a sample does so for th...The atomic force microscope(AFM)can measure nanoscale morphology and mechanical properties and has a wide range of applications.The traditional method for measuring the mechanical properties of a sample does so for the longitudinal and transverse properties separately,ignoring the coupling between them.In this paper,a data processing and multidimensional mechanical information extraction algorithm for the composite mode of peak force tapping and torsional resonance is proposed.On the basis of a tip–sample interaction model for the AFM,longitudinal peak force data are used to decouple amplitude and phase data of transverse torsional resonance,accurately identify the tip–sample longitudinal contact force in each peak force cycle,and synchronously obtain the corresponding characteristic images of the transverse amplitude and phase.Experimental results show that the measured longitudinal mechanical characteristics are consistent with the transverse amplitude and phase characteristics,which verifies the effectiveness of the method.Thus,a new method is provided for the measurement of multidimensional mechanical characteristics using the AFM.展开更多
The main aim of this work is to study numerically the influence of an external magnetic field on the solidification processes of two-component materials. Based on the continuum model of two-phase flow a mathematical m...The main aim of this work is to study numerically the influence of an external magnetic field on the solidification processes of two-component materials. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in a magnetic field is presented. The model includes mass, momentum, energy and species mass conservation equations written in compressible form and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone, which is treated by means of a porous medium approach. The volume fraction of liquid and solid phases, respectively, is calculated from a 2D approximation of the phase diagram. The results of calculation are compared with experimental data.展开更多
基金supported by the U.S.Department of Energy under Award(DE-FE0001321).
文摘The influence of the magnetization of a soft magnetic sphere on the surrounding magnetic field is measured and characterized.The interaction force between two soft magnetic particles is directly measured using an ultra precision load sensor in uniform and non-uniform magnetic fields. The interaction force largely follows an inverse fourth power law as a function of separation distance between particle centers. At small distances,the effect of magnetization of one particle on the magnetization of its adjacent particle causes the attractive(repulsive) force to be larger(smaller) than that predicted by the inverse fourth power law.The theoretical prediction based on a modified dipole model,that takes into account the coupling effect of the magnetization among soft magnetic particles,gives excellent agreement with the measured force in a uniform magnetic field.The interaction force under a non-uniform applied magnetic field can be reasonably predicted using the dipole-dipole interaction model when the local magnetic field is used to determine the magnetization.
基金This work was supported in part by the National Natural Science Foundation of China under Grants 51677169 and 51637009.
文摘This paper presents a comparative investigation into unbalanced magnetic force(UMF)of asymmetric permanent magnet machines without rotor eccentricities,particularly focusing on the difference between internal-and external-rotor topologies.The asymmetric field distribution results in radial and tangential asymmetric force waves.Although the radial and tangential stresses are in different direction,the UMF components they produce are nearly aligned.The UMF from asymmetric radial force wave can be additive or subtractive to that from asymmetric tangential force wave.Investigation shows that for the same pole slot number combination,if the UMFs due to radial and tangential force waves are additive in internal rotor machine,they are subtractive in the external rotor counterpart,and vice versa.Investigation reveals a general rule determining whether additive or cancelling:for a UMF produced by any two field harmonics,they are additive if the higher order is produced by the outer part outside the airgap,but cancelling if the higher order is produced by the inner part.Therefore,for a machine with pole number 2p=3k+1,they are additive if it is an external-rotor machine,but otherwise subtractive.On the other hand,for a machine with pole number 2p=3k-1,they are subtractive if it is an external-rotor machine,but otherwise additive.For the UMF due to armature reaction only,they are subtractive for external-rotor machines,but otherwise additive.The investigation is carried out by an analytical model and validated by finite element analysis.
基金supported by the National Natural Science Foundation of China under Grant[52077027]Liaoning Province Science and Technology Major Project[No.2020JH1/10100020].
文摘In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare comprehensively considered, and the governing equations are solved bysimplifying the boundary conditions. The axial magnetization of the sectorshapedpermanent magnets is accurately described in an algebraic form bythe parameters, which makes the physical meaning more explicit than thepurely mathematical expression in general series forms. The parameters of theBessel function are determined simply and the magnetic field distribution ofpermanent magnets and the air-gap is solved. Furthermore, the field solutionsare completely analytical, which provides convenience and satisfactoryaccuracy for modeling a series of electromagnetic performance parameters,such as the axial electromagnetic force density, axial electromagnetic force,and electromagnetic torque. The correctness and accuracy of the analyticalmodels are fully verified by three-dimensional finite element simulations and a15 kW prototype and the results of calculations, simulations, and experimentsunder three methods are highly consistent. The influence of several designparameters on magnetic field distribution and performance is studied and discussed.The results indicate that the modeling method proposed in this papercan calculate the magnetic field distribution and performance accurately andrapidly, which affords an important reference for the design and optimizationof axial-flux permanent magnet drivers.
基金Supported by the National Natural Science Foundation of China(21325628)the Major Research Plan of the National Natural Science Foundation of China(91334108)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(YZ201641)
文摘For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities(H),leading to the deterioration of the fluidization quality.The critical intensity(H_(ms))above which such segregation commences varies with the gas velocity(U_g).This work focuses on establishing a segregation model to theoretically derive the H_(ms)–U_g relationship.In a magnetic field,the magnetizable particles form agglomerates.The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles.Consequently,the segregation model was established in two steps:first,the size of agglomerates(d_A)was calculated by the force balance model;then,the H_(ms)–U_g relationship was obtained by substituting the expression of d_Ainto the basic size segregation model for binary mixtures.As per the force balance model,the cohesive and collision forces were 1_2 orders of magnitude greater than the other forces exerted on the agglomerates.Therefore,the balance between these two forces largely determined d_A.The calculated d_A increased with increasing H and decreasing U_g,agreeing qualitatively with the experimental observation.The calculated H_(ms)–U_ g relationship agreed reasonably with the experimental data,indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.
文摘After measuring arc electrical current density distribution in gas tungsten arc welding(GTAW) with a probe method, the new expression of body force and model of LD10CS aluminum alloy weld pool are put forward for the first time in GTAW with additional longitudinal magnetic field controlling. The influence of additional longitudinal magnetic field on body force is discussed by electromagnetic principle. This study provides the basis to study fluid flow of the weld pools and arc welding technique with electromagnetic controlling. [
文摘The phenomenon of electrical attraction and repulsion between charged particles is well known, and described mathematically by Coulomb’s Law, yet until now there has been no explanation for why this occurs. There has been no mechanistic explanation that reveals what causes the charged particles to accelerate, either towards or away from each other. This paper gives a detailed explanation of the phenomena of electrical attraction and repulsion based on my previous work that determined the exact wave-function solutions for both the Electron and the Positron. It is revealed that the effects are caused by wave interactions between the wave functions that result in Electromagnetic reflections of parts of the particle’s wave functions, causing a change in their momenta.
基金supported by the National Natural Science Foundation of China(No.51374190)the Major Equipment Fund of Chinese Academy of Sciences(No.YZ201567)
文摘Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field(ExMF). Two types of Ex MFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet(PM) and another generated by an electromagnet(EM) on the order of 2 T. Two forces, including the magnetostatic force between the Ex MF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition,Ex MFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate Ex MF. However, the magnetostatic force will account for a high proportion of the measured force,thus inhibiting the normal LFV operation, if the Ex MF is too high.
基金This project is supported by the General Program of the National Natural Science Foundation of China(62073227)the National Natural Science Foundation of China(61927805 and 61903359).
文摘The atomic force microscope(AFM)can measure nanoscale morphology and mechanical properties and has a wide range of applications.The traditional method for measuring the mechanical properties of a sample does so for the longitudinal and transverse properties separately,ignoring the coupling between them.In this paper,a data processing and multidimensional mechanical information extraction algorithm for the composite mode of peak force tapping and torsional resonance is proposed.On the basis of a tip–sample interaction model for the AFM,longitudinal peak force data are used to decouple amplitude and phase data of transverse torsional resonance,accurately identify the tip–sample longitudinal contact force in each peak force cycle,and synchronously obtain the corresponding characteristic images of the transverse amplitude and phase.Experimental results show that the measured longitudinal mechanical characteristics are consistent with the transverse amplitude and phase characteristics,which verifies the effectiveness of the method.Thus,a new method is provided for the measurement of multidimensional mechanical characteristics using the AFM.
文摘The main aim of this work is to study numerically the influence of an external magnetic field on the solidification processes of two-component materials. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in a magnetic field is presented. The model includes mass, momentum, energy and species mass conservation equations written in compressible form and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone, which is treated by means of a porous medium approach. The volume fraction of liquid and solid phases, respectively, is calculated from a 2D approximation of the phase diagram. The results of calculation are compared with experimental data.