Magnetorheological suspension electromagnetic brake

The magnetorheological suspension (MRS) brake is of the monoblock type. The main part of the electromagnetic brake is an electromagnet, between whose poles two MRS disks are placed. For distances between disks of 0.65×10⁻³ m±10%, revolutions of the electric motor, coupled to the electromagnetic brake, ranging between 200 and 1600 rev/min and braking powers of up to 85 W, there are no differences in revolutions between the disks of the electromagnetic brake. For fixed revolutions of the electric motor, the revolution of the parallel disk can be modified continuously by means of the intensity of the magnetic field. In all cases, the quantity of MRS is of 0.35×10⁻³ kg.     

The modelling of an electromagnetic energy harvesting architecture

In this paper a detailed mathematical model for an electromagnetic energy harvesting architecture based on a semi-analytical approach is introduced. This model estimates the generated energy of the architecture by computing the static and dynamic magnetic and electric fields that describe its dynamics. A comparison of the static fields with the results of a Finite Element Analysis simulation in COMSOL Multiphysics shows good agreement. The model also features increased accuracy and numerical stability. In the model the semi-analytical solutions for the electromagnetic damping force exerted by the induced current coil and the induced electromotive force on the coil provide additional insight into the interactions of electromagnetic induction and damping. Additionally, the energy estimation could be used as a figure of merit in an maximization process to identify the optimal dimensions of the energy harvester.     

A theoretical model for surface bone remodeling under electromagnetic loads

A theoretical model for surface bone remodeling under electromagnetic loads is proposed in this paper. In the model, surface bone remodeling is assumed to be related to growth factors. Growth factors in latent form in osteocytes are released to the bone fluid after the osteocytes are absorbed by osteoclasts, and then regulate the bone formation process. At the same time, environmental loadings can influence the generation of growth factors. This paper shows how surface bone remodeling is triggered under the influence of growth factors. Based on this hypothesis, a computational model is established that simulates the bone coupling remodeling process, including internal and surface bone remodeling. The effects of various loadings, including electrical and magnetic loadings, are simulated and compared. The interactions between internal and surface bone remodeling are investigated via the numerical method. The results indicate that an electromagnetic field can strongly influence the bone remodeling process and that the remodeling process will be altered after surface bone remodeling is triggered, compared to the sole effect of the internal remodeling process.     

A novel electromagnetic induction detector with a coaxial coil for capillary electrophoresis

A novel electromagnetic induction detector with two inductors for CE was described here.The two inductors were used as signal detection and reference,respectively.The parameters affecting the detector performance(including coil turns,detection distance, excitation frequency,voltage,etc.) were optimized.Under the optimum condition,the feasibility of the detector was examined by analyzing inorganic ions.The fabricated detector showed good linear relationship between the response and the analytes concentrations,with a detection limit of 13μmol/L for Na~+(S/N = 3).A variety of advantages,such as simple construction, ease of operation,and considerably universal response,suggested this novel detector a promising application prospect in analytical area.     

Ion cyclotron electrostatic waves in a low-temeprature low-density magnetized plasma

Summary The electrostatic dispersion relation for a low-temperature, low-density magnetized plasma has been studied in the range of the ion cyclotron frequency and its first harmonics. The presence of a forward wave and of an infinite number of backward waves has been shown. The characteristics of propagation of these modes and the possibility of conversion are analysed.

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Riassunto Viene studiata la relazione di dispersione elettrostatica relativa ad un plasma magnetizzato di bassa densità e di bassa temperatura nel campo della frequenza ciclotronica ionica e delle sue prime armoniche. Si mostra la presenza di un unico modo forward e di un insieme infinito di modi backward. Si analizzano le caratteristiche di propagazione di queste onde e la possibilità di conversioni tra di esse.

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Резюме Исследуется электростатическое дисперсионное соотношение для намагниченной плазмы с низкой температурой и низкой плотностью в области ионной циклотронной частоты и ее первой гармоники. Показывается наличие единственной моды в направлении вперед и бесконечного числа волн в обратном направлении. Анализируются характеристики распространения этих мод и возможность конверсии.

     

Energy bounds in dynamical problems for a semi-infinite magnetoelastic beam

The aim of this paper is to investigate the behaviour of the total energy of a magnetoelastic conductor occupying a semi-infinite prismatic cylinder in dynamical conditions. Precisely, we deduce some estimates for the energyW(x ₃,t) of the portion of the medium at distance greater thanx ₃ from the base in terms of the data. First of all, we prove that the total energyW(0,t) is finite for allt > 0 providedW(0, 0) is finite. Then, using the first Korn inequality, we obtain that the estimate forW(x ₃,t) depends only on the initial data ift<x ₃/V (V=computable positive material constant); ift>x ₃/_V then the bound forW(x ₃,t) depends on all the data of the problem.     

A study of 223Ra populated by α-decay

The low spin states of ²²³Ra have been populated via α-decay from ²²⁷Th which was itself produced following β⁻ decay of an ²²⁷Ac source. α–γ and α−e _K,L,M angular correlation measurements have been analysed using the correct ground state spins of ²²⁷Th(=1/2⁺) and ²²³Ra(=3/2⁺) for the first time. The analysis has allowed unique J^π values to be assigned to almost all levels below 400 keV excitation in ²²³Ra. Values of (g _K−g _R)/Q ₀ have been deduced for several members of the K= 3/2^± bands (for the first time in an odd N nucleus in this mass region) allowing estimates of g _K and g _R to be extracted. The values of g _K and g _R are not significantly different for the positive and negative parity band members and tend to support other strong evidence that stable octupole deformation exists in ²²³Ra at low excitation energies. Received: 17 November 1997 / Revised version: 8 January 1998     

Peculiarities of the vortex dynamics in YBa2Cu3Ox single crystals as revealed by irreversible microwave absorption

We report the results of a wide experimental study of the irreversible modulated microwave absorption as a function of temperature, applied magnetic field and modulation amplitude in the YBa₂Cu₃O_x single crystals. To analyze the experimental data the model of the microwave power dissipation by the flux lines has been developed taking into account thermal fluctuations, the distributions of currents and vortices over a sample. We have obtained the information about regimes of vortex motion in the different areas of the H–T phase diagram and estimated the values of flux flow viscosity and critical current density.     

Response of a system of strongly interacting particles to an inhomogeneous external field

We show that a system of N strongly interacting quantum particles in a parabolic confining potential can be unstable under the action of a time-dependent quadrupole external field. The instability leads to the generation or amplification of dipole oscillations. Parameters of the instability are independent of the number of particles and the inter-particle interaction.     

聚芳醚酮基复合吸波材料的制备及性能

以磁性多孔碳(WPC/MNPs-80)作为吸波剂材料, 通过溶液共混方式将其与聚芳醚酮复合, 制备了聚芳醚酮基复合吸波材料(6F-PAEK-Crosslink@WPC/MNPs-80). 为了通过溶液共混的方式制备复合材料并避免成膜过程中吸波剂的沉降问题, 设计合成了含有氨基与六氟异丙基的可溶性可交联型聚芳醚酮(6F-PAEK-NH₂). 结果表明, 在交联剂作用下形成的交联结构不仅避免了吸波剂粒子沉降, 而且还赋予了材料优异的耐热性能和力学性能. 此外, 6F-PAEK-Crosslink@WPC/MNPs-80还具有优异的吸波性能, 当复合膜厚度为1.4 mm时, 最大反射损耗达到了-33 dB, 损耗超过-10 dB的频带宽度达到4.8 GHz; 当复合膜厚度为1.8 mm时, 最大反射损耗为-44.5 dB, 损耗超过-10 dB的频带宽度达到3.1 GHz.因此, 6F-PAEK-Crosslink@WPC/MNPs-80是一种综合性能优异的电磁波吸收材料.