Speed Measurement Feasibility by Eddy Current Effect in the High-Speed MFL Testing

It is known that eddy current effect has a great influence on magnetic flux leakage testing(MFL).Usually,contacttype encoder wheels are used to measure MFL testing speed to evaluate the effect and further compensate testing signals.This speed measurement method is complicated,and inevitable abrasion and occasional slippage will reduce the measurement accuracy.In order to solve this problem,based on eddy current effect due to the relative movement,a speed measurement method is proposed,which is contactless and simple.In the high-speed MFL testing,eddy current induced in the specimen will cause an obvious modification to the applied field.This modified field,which is measured by Hall sensor,can be utilized to reflect the moving speed.Firstly,the measurement principle is illustrated based on Faraday’s law.Then,dynamic finite element simulations are conducted to investigate the modified magnetic field distribution.Finally,laboratory experiments are performed to validate the feasibility of the proposed method.The results show that Bmz(r1)and Bmx(r2)have a linear relation with moving speed,which could be used as an alternative measurement parameter.

MHz cut-off frequency and permeability mechanism of iron-based soft magnetic composites

The lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in the efficient operation of the electrical and electronic equipments.Here,a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds of MHz is reported.The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of the ring,the distribution of particles,and the particle size.The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect.An empirical formula for the cut-off frequency in a magnetic ring composed of iron-based particles is established from experimental data.This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in hundreds of MHz.

Analysis of substrate eddy effects and distribution effects in silicon-based inductor model

The concepts of substrate eddy influence factor and distribution-effects-occurring frequency are presented. The effects of substrate resistivity and inductor spiral length on the substrate eddy and distribution effects are captured. The substrate eddy influence factors of an inductor （6 turn, 3 060 μm in length） fabricated on low （ 1 Ω. cm） and high resistivity（ 1 000 Ω.cm） silicon substrates are 0. 3 and 0. 04, and the distribution-effects- occurring frequencies are 1.8 GHz and 14. 5 GHz, respectively. The measurement results show that the equivalent circuit model of the inductor on low resistivity silicon must take into consideration substrate eddy effects and distribution effects. However, the circuit model of the inductor on high resistivity silicon cannot take into account the substrate eddy effects and the distribution effects at the frequencies of interest. Its simple model shows agreement with the measurements, and the contrast is within 7%.

Recent progress in compressible turbulence

In this paper, we review some recent studies on compressible turbulence conducted by the authors＇ group, which include fundamental studies on compressible isotropic turbulence （CIT） and applied studies on developing a con- strained large eddy simulation （CLES） for wall-bounded turbulence. In the first part, we begin with a newly pro- posed hybrid compact-weighted essentially nonoscillatory （WENO） scheme for a CIT simulation that has been used to construct a systematic database of CIT. Using this database various fundamental properties of compressible turbulence have been examined, including the statistics and scaling of compressible modes, the shocklet-turbulence interac- tion, the effect of local compressibility on small scales, the kinetic energy cascade, and some preliminary results from a Lagrangian point of view. In the second part, the idea and for- mulas of the CLES are reviewed, followed by the validations of CLES and some applications in compressible engineering problems.

The combination of eddy thermal effect of biodegradable magnesium with immune checkpoint blockade shows enhanced efficacy against osteosarcoma

Osteosarcoma(OS)patients have a poor prognosis due to its high degree of heterogeneity and high rate of metastasis.Magnetic hyperthermia therapy(MHT)combined with immunotherapy is an effective strategy to treat solid and metastatic tumors.Here,we combined biodegradable magnesium(Mg)macroscale rods,which acted as an eddy thermo-magnetic agent under a low external alternating magnetic field,and immunotherapy to achieve a radical cure for OS.The eddy thermal effect(ETE)of the Mg rods(MgR)showed outstanding cytotoxic effects and enhanced the maturation of dendritic cells(DCs),and the mild MHT induced the immunogenic cell death(ICD)in the OS cells.Combined with immune checkpoint blockade(ICB)therapy,we obtained an excellent curative effect against OS,and a further evaluation demonstrated that the local MHT induced by the MgR increased T cells infiltration and the polarization of M1 macrophages.Interestingly,the biodegradable MgR also promoted bone osteogenesis.Our work highlighted the uneven ETE mediated by the biodegradable MgR induced a comprehensive immunologic activation in the OS tumor microenvironment(TME),which would inspire the application of MHT for the effective treatment of OS.

Design and first result of combined Langmuir-magnetic probe on J-TEXT tokamak

In order to measure boundary electrostatic and magnetic fluctuations simultaneously,a combined Langmuir-magnetic probe(CLMP)has been designed and built on joint-Texas experimental tokamak.The probe consists of 8 graphite probe pins and a 3D magnetic probe,driven by a mechanical pneumatic device.By means of simulation,the shielding effect of the graphite sleeve on the magnetic fluctuation signal is explored,and the influence of the eddy current was reduced by cutting the graphite sleeve.In the experiment,it has been verified that the mutual inductance of electromagnetic signals can be ignored,and a 70–90 k Hz electromagnetic mode is observed around the last closed magnetic surface.The establishment of CLMP provides data for the exploration of the coupling of electrostatic and magnetic fluctuations.

ANALYSIS ON DYNAMIC CHARACTERISTICS FOR FERROMAGNETIC CONDUCTING PLATES IN A TRANSVERSE UNIFORM MAGNETIC FIELD

In this paper, a set of basic equations for free vibration of ferromagnetic conducting plates in a transverse magnetic field are presented, in which the coupled effects of magnetization and eddy current on the mechanical behavior of the plate are included. Based on the quantitative analyses on the vibration frequency and the values of the critical magnetic field for several supporting conditions of the plate, the effects of the conductivity, the magnetic permeability, the thickness of the plate and supporting conditions on the vibration frequency of the plate and the critical magnetic field are discussed.

An accurate RLGC circuit model for dual tapered TSV structure

A fast RLGC circuit model with analytical expression is proposed for the dual tapered through-silicon via （TSV） structure in three-dimensional integrated circuits under different slope angles at the wide frequency region. By describing the electrical characteristics of the dual tapered TSV structure, the RLGC parameters are extracted based on the numerical integration method. The RLGC model includes metal resistance, metal inductance, substrate resistance, outer inductance with skin effect and eddy effect taken into account. The proposed analytical model is verified to be nearly as accurate as the Q3D extractor but more efficient.