Rectangular Magnets Research Articles

Numerical study and design optimization of electromagnetic energy harvesters integrated with flexible magnetic materials

This study presents a new design of an electromagnetic energy harvester integrated with a soft magnetic material. The harvester design optimizes the magnetic material characteristics and the size of a rectangular permanent magnet. The design employs a complete magnetic circuit made of (1) a thin-film soft magnetic material that facilitates a flexible but highly (magnetically) permeable beam and (2) an optimally-sized magnet that maximizes the harvester performance. The design is demonstrated to reduce magnetic flux leakage, and thus considerably enhances both magnetic flux density (B) and its change by time (dB/dt), which both influence harvester performance. The improvement in harvester performances strongly depends on critical design parameters, especially, the magnet size and characteristics of magnetic materials, including permeability, stiffness, and thickness. The analyses conclude that recently-introduced nanomaterials (having ultrahigh magnetic permeability) can potentially innovate harvester performances. However, the performance may be degraded without design optimization. Once optimized, the integrated nanomaterials facilitate a significant improvement compared with a conventional design without integrated magnetic materials.

INVESTIGATION OF INFLUENCE OF SEPARATOR MAGNETIC SYSTEM CONFIGURATION WITH PERMANENT MAGNETS ON MAGNETIC FIELD DISTRIBUTION IN WORKING AREA

Purpose. To carry out research the influence of magnetic system configuration (shape and size of the permanent magnets) on magnetic field spatial distribution in working area of new structure design magnetic separator with active front surface by numerical methods. Methodology. We have applied the magnetic field numerical simulation for permanent magnets system in absence of electrical current in magnetostatic approximation. We have solved the problem by using finite element method. Research of permanent magnets cross-sectional shape influence made in the two-dimensional formulation using software package Elcut. Research of magnetic field induction spatial (three-dimensional) distribution in new construction magnetic separator working area is conducted using software package COMSOL Multiphysics 3.5a. Results. Magnetic flux density maximum in the immediate vicinity of permanent magnet surface provide magnets with spherical and trapezoidal cross-sectional shape. At a distance from pole surface, where the separation process working, magnetic field density produced by trapezoidal and spherical cross section magnets, substantially lower in comparison with rectangular magnets. Rectangular and rectangular with beveled corners cross-section shape magnets create approximately same magnetic field intensity not significantly different in weight. Analysis of the spatial distribution of magnetic field induction in the working area of a new construction magnetic separator has shown that a strong magnetic field with high magnetic flux density gradient value is formed in the interpolar working volume. Originality. For the first time research of magnetic flux density distribution in working area of new construction magnetic separator is conducted. Developed device feature is complex spatial distribution of magnetic field. Practical value. Results of research can be used for selection of rational parameters of separator magnetic system. Received results also can be used for determination of separator force characteristics.

Portable Pico Linear Generator Design with Different Magnet Shapes for Wave Energy Conversion System

There are abundant of wave energy converter technologies available to convert wave energy into useable energy. However, most of them are huge and suitable for large application. Thus, this paper aimed to propose portable pico generator designs for small scale application. Investigation on the performance of designs with varying halbach magnet shapes was mainly focused and discussed. Two designs of different magnet shape i.e. triangular and trapezoid were proposed. Open-circuit simulation and optimization results were obtained using Finite Element Method. From the results, it was found out that Trapezoid Magnet Design produced better performance and lower material cost compared to another proposed design, Triangular Magnet as well as conventional Rectangular Magnet shape.

Magnetic Properties and Defects of Fe-Ni-Based Magnetic Microwires

We studied the magnetic properties and domain wall (DW) dynamics of Fe47.4Ni26.6Si11B13C2 and Fe77.5Si7.5B15 microwires. Both samples present a rectangular hysteresis loop and fast magnetization switching. The linear region of dependence of the DW velocity on the magnetic field in Fe47.4Ni26.6Si11B13C2 sample is considerably shorter. Consequently, we studied the structure of Fe47.4Ni26.6Si11B13C2 sample using X-ray diffraction and atom probe tomography. The results obtained using the atom probe tomography supports the formation of B-enriched precipitates in the interfacial layer and in the metallic nucleus after annealing.

Hybrid high gradient permanent magnet quadrupole

This paper presents an innovative compact permanent magnet quadrupole with a strong gradient for potential use in future light source lattices. Its magnetic structure includes simple mechanical parts, rectangular permanent magnet blocks and soft iron poles. It has a wide aperture in the horizontal plane to accommodate an x-ray beam port, a common constraint in storage ring-based light sources. This specificity introduces field quality deterioration because of the resulting truncation of the poles; a suitable field quality can be restored with an optimized pole shape. A $82\text{ }\text{ }\mathrm{T}/\mathrm{m}$ prototype with a bore radius of 12 mm and a 10 mm vertical gap between poles has been constructed and magnetically characterized. Gradient inhomogeneities better than ${10}^{\ensuremath{-}3}$ in the good field region were obtained after the installation of special shims.

A Novel Ferrofluid Inclinometer Exploiting a Hall Element

This paper presents a novel inclinometer based on the second kind of ferrofluid levitation principle. Two rectangular magnets with the opposite poles are fixed at the ends of a non-magnetic retainer to generate a symmetric non-uniform magnetic field. A Hall element is fixed to the inner wall of the container located at the center of two magnets. When the device inclines, the movement of the ferrofluid surrounding the magnets as an inertial mass will change the magnetic field acting on the Hall element. Meanwhile, the Hall element will detect the change of the magnetic field and transmit the signal. Some static and dynamic characterizations of the inclinometer with different geometric parameters are obtained through the theoretical calculation and experimental measurement. The satisfactory linearity and the high sensitivity indicate the feasibility of the ferrofluid inclinometer.

Energy conversion by ‘T-shaped’ cantilever type electromagnetic vibration based micro power generator from low frequency vibration sources

The design, development, and analyses of low-frequency vibration based T-shaped cantilever type electromagnetic micro power generators (EVMPGs) are presented in this paper. Four different configurations (Configurations A to D) of EVMPGs were designed and fabricated and subsequently characterized using detailed experimental and limited analytical techniques. Configuration A and B consisted of a single and a double cylindrical moving magnets (NdFeB), respectively, while Configuration C consisted of four rectangular moving magnets with respect to a fixed copper coil. In contrast, Configuration D used a moving coil between four rectangular magnets with a back-iron bar. The open circuit RMS voltage output was observed to be a maximum from Configuration D (98.2mV at 6.29Hz) with a base vibration acceleration of 0.8ms−2. Therefore, Configuration D was selected for further experimental investigations, which included changing the back-iron bar thickness, changing the base acceleration level, and changing the air gap separation between the magnets in order to optimize this configuration. The maximum load RMS voltage and power outputs of Configuration D were 105.4mV and 1.35mW at 6.29Hz for load resistance 8.2Ω and a base acceleration of 0.8ms−2 with a 4.2mm back-iron bar when the air gap between the magnets was 20mm. Finally, a small portable EVMPG prototype was developed based on the Configuration D and was tested at different human movement conditions (i.e., walking, quick walking, and running). The developed EVMPG prototype was capable of harvesting 35.2mV and 0.22mW at 7Hz with load resistance 5.6Ω for a base acceleration of 0.8ms−2.

The experiment study of the sensing mechanism of thermal magnetic type oxygen sensor

The oxygen sensor is widely used in daily life. Thermal magnetic type oxygen sensor has some advantages such as long service life and high accuracy of measurement. It skillfully uses the change of the wall temperature that caused by the thermal magnetic convection phenomenon to sense the change of oxygen concentration. For a paramagnetic gas, the thermal megnetic convection is caused by the interaction between the temperature field and the magnetic field as the gradient of the magnet field and the temperature gradient both existing at the same time. The intensity of thermal megnetic convection is determined by the magnetic susceptibility of a gas and the gradient of H 2 (where H is the induced magnet field). Oxygen is a common paramagnetic gas, the magnetic susceptibility of oxygen has a much higher than other gas, thus, the oxygen concentration of a gas can be detected by the thermal magnetic convection phenomenon. However, the thermal magnetic convection phenomenon is complicated, The sensing mechanism of this type sensor is not clear. Therefore, it is necessary to study the sensing mechanism in-depth to improve the accuracy and efficencey of thermal magnetic type oxygen sensor. This paper, by means of experiments, studies the wall temperature change characteristics of the thin-wall circular tube in a non-uniform magnetic field generated by two pieces of rectangular permanent magnets. In the experiment, a quartz glass tube with a thin wall thickness was used as the channel through which the measured gas flows. Two permanent magnets are arranged outside the quartz tube, which are used to provide the magnetic field required for the thermal magnetic convection. A kind of the sensitive element with double helically wounded resistance wires is designed. In which two resistance wires with different temperature coefficient are helically wounded on the wall of outside the quartz tube, one is the Manganin resistance wire for heating, and one is the platinum wire for measuring the temperature of tube wall. The loops of the heating and the temperature measurement are separated, which is favorable for study of the thermal magnetic type oxygen sensor. The permanent magnets used in the experiment have the remanence of 1.32 T. The ambient temperature around the sensitive element is measured by the thermocouple. The experimental device, which includes the sensitive element and some appropriately insulating elements, is placed in a rectangular cavity, and the size of the square cavity is much larger than the sensitive element. By comparing temperature difference of the tube wall, the increment of the convective heat transfer coefficient and the increment of velocity under conditions with and without the magnetic field to illustrate the relationship of the thermal magnetic convection phenomenon and heating power, oxygen concentration and other parameters. It is found that when magnetic field is pesent, the surface temperature of the tube wall is significantly lower than that of the case without magnetic field, and with the increase of heat flux, the surface temperature of tube wall decreases significantly. The relationship between the heat flux density and the change of the wall temperature is nearly liner.With the increase of heat flux density, the increasments of average velocity and convective heat transfer coefficient caused by the thermal magnetic convection phenomenon increase. When oxygen content increases by 10%, the temperature of the tube wall decreases by 0.12°C. The resolution of the studied oxygen concentration senser is about 0.08%.

Axial force measurement for U-bolt using wave propagation speed monitoring

It is important to inspect clamped parts of a produced vehicle in the manufacturing process non-destructively. In this study, a measuring device of axial force is suggested by utilizing relations between wave propagation characteristics of a beam and a clamping force. Experiments were carried out to determine characteristics of vibration signals for the structure designed for inspection. Neodymium magnet was utilized as the components of the device to attach to the joint without any damage to the products. A rectangular parallelepiped magnet was used to detect the change in the wave propagation speeds in the structure. The change in the wave propagation through the bolt was measured and used in estimation of the axial force. The correlation coefficient was calculated to quantify the change in the wave propagation characteristics. The coefficient was utilized to determine the axial force of the bolted joint by the experiment. The proposed method was applied to actual U-bolts to validate the methodology.

Fabrication and integration of microscale permanent magnets for particle separation in microfluidics

Microfluidic magnetophoresis is an effective technique to separate magnetically labeled bioconjugates in lab-on-a-chip applications. However, it is challenging and expensive to fabricate and integrate microscale permanent magnets into microfluidic devices with conventional methods that use thin-film deposition and lithography. Here, we propose and demonstrate a simple and low-cost technique to fabricate microscale permanent magnetic microstructures and integrate them into microfluidic devices. In this method, microstructure channels were fabricated next to a microfluidic channel and were injected with a liquid mixture of neodymium (NdFeB) powders and polydimethylsiloxane (PDMS). After the mixture was cured, the resulted solid NdFeB–PDMS microstructure was permanently magnetized to form microscale magnets. The microscale magnets generate strong magnetic forces capable of separating magnetic particles in microfluidic channels. Systematic experiments and numerical simulations were conducted to study the geometric effects of the microscale magnets. It was found that rectangular microscale magnets generate larger \(({\mathbf {H}}\cdot \nabla ) {\mathbf {H}}\) which is proportional to magnetic force and have a wider range of influence than the semicircle or triangle magnets. For multiple connected rectangular microscale magnet, additional geometric parameters, including separation distance, height and width of the individual elements, further influence the particle separation and were characterized experimentally. With an optimal size combination, complete separation of yeast cells and magnetic microparticles of similar sizes (\(4\;\upmu \hbox {m}\)) was demonstrated with the multi-rectangular magnet microfluidic device.

Application of a Halbach magnetic array for long-range cell and particle separations in biological samples

Here, we describe a versatile application of a planar Halbach permanent magnet array for an efficient long-range magnetic separation of living cells and microparticles over distances up to 30 mm. A Halbach array was constructed from rectangular bar magnets using 3D-printed holders and compared to a conventional alternating array of identical magnets. We theoretically predicted the superiority of the Halbach array for a long-range magnetic separation and then experimentally validated that the Halbach configuration outperforms the alternating array for isolating magnetic microparticles or microparticle-bound bacterial cells at longer distances. Magnetophoretic velocities (ymag) of magnetic particles (7.9 μm diameter) induced by the Halbach array in a microfluidic device were significantly higher and extended over a larger area than those induced by the alternating magnet array (ymag = 178 versus 0 μm/s at 10 mm, respectively). When applied to 50 ml tubes (∼30 mm diameter), the Halbach array removed >95% of Staphylococcus aureus bacterial cells bound with 1 μm magnetic particles compared to ∼70% removed using the alternating array. In addition, the Halbach array enabled manipulation of 1 μm magnetic beads in a deep 96-well plate for ELISA applications, which was not possible with the conventional magnet arrays. Our analysis demonstrates the utility of the Halbach array for the future design of devices for high-throughput magnetic separations of cells, molecules, and toxins.

Magnetic field intensity in Halbach trapezoidal magnet array of magnetically levitated planar actuators

The effects of magnetic steel shapes on air-gap magnetic flux density in Halbach magnet array of magnetically levitated planar actuators were investigated. After rectangular magnetic steel was replaced by trapezoidal magnetic steel, we deduced the magnetic flux density in Halbach rectangular magnet array using Fourier series and magnetic scalar potential. The analytical expressions of magnetic flux density in trapezoidal magnet array were obtained using the principle of superposition and the infinitesimal analysis of magnetic steel. The higher harmonic error (root-mean-square) and the relation of each harmonic peak to the ratio of length-to-polar distance at y-direction magnetised steel were investigated in Halbach trapezoidal magnet array. After the structural parameters were optimised, we analysed the effects of rolling angle of trapezoid on the y-direction magnetic field intensity, and found out the optimal rolling angle. The structural analysis shows that the trapezoidal magnetic steel can change the air-gap magnetic flux density in a very large space.

Edge-Mode Resonance-Assisted Switching of Nanomagnet Logic Elements

We study the ferromagnetic resonance (FMR) modes of arrays consisting of elements of supermalloy-based nanomagnet logic devices: individual rectangular magnets, lengthwise-coupled magnet pairs, and driver-input magnet pairs. In FMR experiments, we observe a center resonance mode for all three samples. Furthermore, edge modes can be resolved for arrays with individual rectangular magnets and lengthwise-coupled magnet pairs. By micromagnetic simulations, the characteristics of the experimentally observed precession modes are elaborated, and distinct edge modes not visible in the experiments are revealed. Based on these numerical investigations, we propose a new addressing scheme to switch a specific element of the driver-input magnet pair based on resonant excitation of the unique edge-mode resonance of the element. This new switching scheme could significantly reduce switching power and increase bit selectivity, and hence programming reliability.

Comparative Study of Linear Permanent Magnet Generator with Different Shape of Permanent Magnet for Wave Energy Conversion

This paper presents the design of linear permanent magnet generator for wave energy conversion using finite element analysis software. Four designs have been proposed which are simple, lightweight, portable and can produce 100 Watt electric power. Air-cored linear permanent magnet generator have been chosen and their electromagnetic characteristic were analyzed using finite element analysis. The determined electromagnetic analysis reveals that rectangular permanent magnet arrangement (Rect-PM) design gives efficient performance as compared to other designs.

The Development and Characterization of SMT Typed Slim Micro-speaker for Mini Multimedia Devices

본 논문은 마이크로 스피커 설계에 관한 연구로 보이스 코일과 전극 연결에 SMT를 적용할 수 있도록 개선된 보이스 코일 및 이를 이용한 마이크로 스피커에 관한 것이다. 특히 스피커 단자를 SMT방식에 의해서 PCB기판에 실장하고 하나의 모듈로 프레임에 결함함으로써 스피커 단자를 PCB기판의 스피커 실장부 위치에 정확히 실장 할 수 있는 장점이 있다. 기존 원형 magnet 크기보다 작은 사각형 magnet을 적용하였으나 음압은 기존과 동등 수준이며, 폴리에텔에텔 케톤과 알루미늄 적층막으로 구성한 2중 진동판을 사용하여 200Hz~1KHz 사이에 SPL을 개선하였고, 8KHz 대역에서의 Deep현상을 제거하였다. 300Hz~800Hz사이의 THD를 30%에서 10%이내로 개선하였으며 저음 음질도 향상 되었다.

Mat Lab Simulation and Programming for Wireless Power Transfer through Concrete

Wireless power transmission using circuits resonating at the frequency of 50 Hz and 60 Hz. The purpose of this research paper is to develop a matlab simulation and matlab programming for calculating efficiency and max efficiency of the system for transmitting electrical power through concrete walls. The transmission efficiency that considers the copper and core losses was derived through equivalent circuit analysis. The transmission efficiency was found to be dependent on the shape of the magnet pole pieces. A transmission efficiency of 78.54%. And max efficiency of 76.57% for a load of 146.5 ohms for a rectangular shape magnet. In this paper for two different frequencies, efficiency and max efficiency is calculated and tabulated along with the magnetic field distribution. DOI: 10.17762/ijritcc2321-8169.1507105

Magnetic force analytic model of step conical PMB

The cost of precision conical permanent magnetic bearings (PMB) is very expensive in the engineering manufacture. Step conical PMB, which consists of by piling up several couples PM rings of different diameters with rectangular cross section, in a conic disposition, characterized by such advantages as low cost and easy manufacture. Based on the magnetic field of planar point magnetic charge, virtual work principle, and superposition theorem, combining two parallel rectangular section permanent magnets (PM) and the structure trait of step conical PMB, the magnetic force analytical model of step conical PMB is established, and the relationship between magnetic force and structure parameters of step conical PMB is analyzed, and the correctness of the magnetic force analytical model is validity by ANSYS simulation, comparisons show that the analytical solution closely matches with the results of the finite element analysis. The results indicate that the magnetic force of step conical PMB is proportional to the magnetic annular average perimeter and the square of residual magnetism induction density, and that the magnetic force increases with an increment in the magnetic annular section size, the axial magnetic force increases with an increment in the axial deflection, the radial magnetic force increases with an increment in the radial deflection. The paper provides technical support for design and structure parameters optimization of step conical PMB.

Numerical Optimization Approach of the Gap between the Magnet and Coil for Electromagnetic Vibration Energy Harvesters Design

In the design of the micro electromagnetic vibration harvester, an important goal is maximization of the magnetic flux linkage gradient, which directly determines the induced voltage and output power of the electromagnetic vibration harvester. This paper established a numerical model based on structure of the electromagnetic vibration energy harvester. An analytic expression for the magnetic field of rectangular permanent magnets is used to build up an electromagnetic coupling model. The magnetic field distribution of the rectangular permanent magnet was analyzed. The effects of the gap between the magnet and the coil on the load voltage of the electromagnetic vibration energy harvester were investigated. According to the formula, the magnetic flux linkage and flux gradient were calculated to optimize the geometrical parameter of the magnet and coil. The method and boundary conditions of optimizing the gap between the magnet and coil were presented. The maximum output voltage can be obtained by optimizing the gap between the magnet and the coil. A simple prototype was fabricated and measured to validate the theoretical deducing and the feasibility of method.

Textile‐to‐rigid microstrip transition using permanent magnets

A novel transition between a rigid-substrate and a flexible-substrate microstrip for use in wearable devices is described. The contact force between the conductors of the two microstrips is supplied by a pair of rectangular magnets. A simulation and measurement study carried out on a test jig comprising a back-to-back pair of such transitions demonstrated an insertion loss of better than 0.5 dB/transition can be achieved in the range of 0-3 GHz.

G1000205 磁束集中を利用した3自由度磁路制御式磁気浮上装置の開発

A flux-path magnetic suspension system was fabricated in which the three-degree-of-freedom motions of the floator was actively controlled. In this system, a control plate with four rectangular permanent magnets for magnetic concentration were used instead of ferromagnetic control plates in the conventional flux-path magnetic suspension system to increase the suspension force. The three-degree-of-freedom motions of the control plate were controlled with four differential electromagnetic actuators according to the motions of the floator. Contactless suspension was achieved by applying PD control in the fabricated suspension system.