scholarly journals Magnetically Induced Flow Focusing of Non-Magnetic Microparticles in Ferrofluids under Inclined Magnetic Fields

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 56 ◽  
Author(s):  
Laan Luo ◽  
Yongqing He
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Critical Reynolds Number ◽  
Rotation Angle ◽  
Flow Focusing ◽  
Particle Focusing ◽  
Inlet Flow Rate ◽  
Induced Flow ◽  
Angle Of Rotation

The ability to focus biological particles into a designated position of a microchannel is vital for various biological applications. This paper reports particle focusing under vertical and inclined magnetic fields. We analyzed the effect of the angle of rotation (θ) of the permanent magnets and the critical Reynolds number (Rec) on the particle focusing in depth. We found that a rotation angle of 10° is preferred; a particle loop has formed when Re < Rec and Rec of the inclined magnetic field is larger than that of the vertical magnetic field. We also conducted experiments with polystyrene particles (10.4 μm in diameter) to prove the calculations. Experimental results show that the focusing effectiveness improved with increasing applied magnetic field strength or decreasing inlet flow rate.

Influence of Permanent Magnets Installation Approach on the Torque of а Magneto-Rheological Disk Brake

2021 ◽  
Vol 105 ◽  
pp. 184-193
Author(s):  
Ilya Aleksandrovich Frolov ◽  
Andrei Aleksandrovich Vorotnikov ◽  
Semyon Viktorovich Bushuev ◽  
Elena Alekseevna Melnichenko ◽  
Yuri Viktorovich Poduraev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetorheological Fluid ◽  
Simulation Modelling ◽  
Disc Brake ◽  
Large Area ◽  
Braking Torque ◽  
The Magnetic Field

Magnetorheological braking devices function due to the organization of domain structures between liquid and solid magnetic materials under the action of an electromagnetic or magnetic field. The disc is most widely used as a rotating braking element that made of a solid magnetic material due to the large area of contact with a magnetorheological fluid. Many factors affect the braking characteristics of the magnetorheological disc brake. Specifically, the value of the magnetic field and how the field is distributed across the work element is significantly affected at the braking torque. There are different ways to generate a magnetic field. In this study, the method of installation of permanent magnets into the construction, allowing to increase the braking torque of the magnetorheological disc brake is proposed. Simulation modelling showing the distribution of the magnetic field across the disk depending on the installation of permanent magnets with different pole orientations were carried out. The model takes into account the possibility of increasing the gap between solid magnetic materials of the structure, inside them which the magnetorheological fluid is placed. Comparative estimation of the distribution of the magnetic fields depending on the chosen method of installation of permanent magnets with different orientations of their poles is carried out. Further research is planned to focus on a comparative assessment of the distribution of magnetic fields depending on the selected material of the braking chamber.

Surface Roughness Optimization in End Milling of Stainless Steel AISI 304 with Uncoated WC-Co Insert Under Magnetic Field

2012 ◽  
Vol 576 ◽  
pp. 119-122 ◽  
Author(s):  
A.K.M. Nurul Amin ◽  
Syidatul Akma Sulaiman ◽  
Siti Noor Izzati Mohd Zainun ◽  
M.D. Arif
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
End Milling ◽  
Desirability Function ◽  
Low Carbon Steel ◽  
Machining Process ◽  
Low Carbon ◽  
Novel Approach

Chatter phenomenon is a major issue as it greatly affects the topography of machined parts. Due to the inconsistent character of chatter, it is extremely difficult to predict resultant surface roughness in a machining process, such as end milling. Also, recent studies have shown that chatter can be suitably damped using magnetic fields. This paper, thus, focuses on a novel approach of minimizing surface roughness in end milling of Mild (Low Carbon) Steel using uncoated WC-Co inserts under magnetic field from permanent magnets. In this experiment, Response Surface Methodology (RSM) approach using DESIGN EXPERT 6.0 (DOE) software was used to design the experiments. The experiments were performed under two different cutting conditions. The first one was cutting under normal conditions, while the other was cutting under the application of magnetic fields from two permanent magnets positioned on opposite sides of the cutter. Surface roughness was measured using Mitutoyo SURFTEST SV-500 profilometer. The subsequent analysis showed that surface roughness was significantly reduced (by as much as 67.21%) when machining was done under the influence of magnetic field. The experimental results were then used to develop a second order empirical mathematical model equation for surface roughness and validated to 95% confidence level by using ANOVA. Finally, desirability function approach was used to optimize the surface roughness within the limiting values attainable in end milling.

scholarly journals MEASUREMENT AND MODELLING OF GRADIENT MAGNETIC FIELDS FOR BIO-CHEMICAL SEPARATION PROCESSES

2021 ◽  
Vol 5 (2) ◽  
pp. 69-80
Author(s):  
Hatice Bilgili ◽  
Teymuraz Abbasov ◽  
Yusuf Baran
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Gradient ◽  
Permanent Magnets ◽  
Magnetic Field Gradient ◽  
Chemical Separation ◽  
Submicron Particles ◽  
Separation Processes ◽  
Measuring Device ◽  
The Magnetic Field

Separation processes are widely used in chemical and biotechnical processes. Especially biomagnetic separation is an important issue among effective separation processes to separate the magnetic micron and submicron particles. It is necessary to establish and determine a high magnetic field or field gradient in the separation cell. However, it is not easy to determine the magnetic field gradient in the working region for different separation in practice. The reason for these difficulties is that the magnetic cells used in biochemical separation have different geometries and there are no simple and useful systems to easily measure these magnetic fields. Two main objectives are aimed in this study. First, a simple measuring device design can measure gradient magnetic fields with high precision of about 0,01mm and, secondly, obtain simple empirical expressions for the magnetic field. A magnetometer with Hall probes that works with the 3D printer principle was designed and tested to measure the magnetic field. Magnetic field changes were measured according to the surface coordinates on the measurement platform or measuring cell. Numerous experimental measurements of gradient magnetic fields generated by permanent magnets have been taken. The results obtained from the studies and results from the proposed empirical models were compared.

scholarly journals Procedure for selecting optimal geometric parameters of the rotor for a traction non-partitioned permanent magnet-assisted synchronous reluctance motor

2021 ◽  
Vol 6 (8 (114)) ◽  
Author(s):  
Borys Liubarskyi ◽  
Dmytro Iakunin ◽  
Oleh Nikonov ◽  
Dmytro Liubarskyi ◽  
Vladyslav Vasenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Finite Element ◽  
Permanent Magnets ◽  
Geometrical Parameters ◽  
Synchronous Reluctance Motor ◽  
Reluctance Motor ◽  
Electromagnetic Momentum ◽  
Conditional Optimization ◽  
Angle Of Rotation

This paper reports the construction of a mathematical model for determining the electromagnetic momentum of a synchronous reluctance motor with non-partitioned permanent magnets. Underlying it is the calculation of the engine magnetic field using the finite-element method in the flat-parallel problem statement. The model has been implemented in the FEMM finite-element analysis environment. The model makes it possible to determine the engine's electromagnetic momentum for various rotor geometries. The problem of conditional optimization of the synchronous reluctance motor rotor was stated on the basis of the rotor geometric criteria. As an analysis problem, it is proposed to use a mathematical model of the engine's magnetic field. Constraints for geometric and strength indicators have been defined. The Nelder-Mead method was chosen as the optimization technique. The synthesis of geometrical parameters of the synchronous reluctance motor rotor with non-partitioned permanent magnets has been proposed on the basis of solving the problem of conditional optimization. The restrictions that are imposed on optimization parameters have been defined. Based on the study results, the dependence of limiting the angle of rotation of the magnet was established on the basis of strength calculations. According to the calculation results based on the proposed procedure, it is determined that the optimal distance from the interpole axis and the angle of rotation of magnets is at a limit established by the strength of the rotor structure. Based on the calculations, the value of the objective function decreased by 24.4 % (from −847 Nm to −1054 Nm), which makes it possible to significantly increase the electromagnetic momentum only with the help of the optimal arrangement of magnets on the engine rotor. The results of solving the problem of synthesizing the rotor parameters for a trolleybus traction motor helped determine the optimal geometrical parameters for arranging permanent magnets.

scholarly journals Rotation of Liquid Metal Droplets Solely Driven by the Action of Magnetic Fields

2019 ◽  
Vol 9 (7) ◽  
pp. 1421 ◽  
Author(s):  
Jian Shu ◽  
Shi-Yang Tang ◽  
Sizepeng Zhao ◽  
Zhihua Feng ◽  
Haoyao Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Liquid Metal ◽  
Permanent Magnets ◽  
The Self ◽  
Rotating Magnetic Field ◽  
Fluid Mixture ◽  
Cooling Fluid ◽  
Novel Method ◽  
Metal Droplets

The self-rotation of liquid metal droplets (LMDs) has garnered potential for numerous applications, such as chip cooling, fluid mixture, and robotics. However, the controllable self-rotation of LMDs utilizing magnetic fields is still underexplored. Here, we report a novel method to induce self-rotation of LMDs solely utilizing a rotating magnetic field. This is achieved by rotating a pair of permanent magnets around a LMD located at the magnetic field center. The LMD experiences Lorenz force generated by the relative motion between the droplet and the permanent magnets and can be rotated. Remarkably, unlike the actuation induced by electrochemistry, the rotational motion of the droplet induced by magnetic fields avoids the generation of gas bubbles and behaves smoothly and steadily. We investigate the main parameters that affect the self-rotational behaviors of LMDs and validate the theory of this approach. We further demonstrate the ability of accelerating cooling and a mixer enabled by the self-rotation of a LMD. We believe that the presented technique can be conveniently adapted by other systems after necessary modifications and enables new progress in microfluidics, microelectromechanical (MEMS) applications, and micro robotics.

scholarly journals Magnetic field frequency optimisation for MFL imaging using QWHE sensors

2020 ◽  
Vol 62 (7) ◽  
pp. 396-401
Author(s):  
J M Watson ◽  
C W Liang ◽  
J Sexton ◽  
M Missous
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Power Consumption ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Permanent Magnets ◽  
Low Frequency ◽  
Step Size ◽  
Lift Off

Magnetic particle and other magnetic flux leakage (MFL)-based methods for the detection and evaluation of surfacebreaking flaws in ferromagnetic materials typically use high-strength (∼0.5 T RMS) low-frequency (≤50 Hz) magnetic fields. The rationale behind this is the ready availability of strong permanent magnets and mains power for highstrength electromagnets. This high field strength is needed to saturate the sample and compensate for the insensitivity of magnetic particles, silicon Hall sensors, coils and other magnetic transducers. Consequently, the frequency of the applied magnetic field is typically limited to ≤50 Hz and does not consider the frequency response of the material under test (some MFL applications use this low frequency to detect subsurface or flaws on the backwall). In this study, a probe consisting of a quantum well Hall-effect (QWHE) sensor, an illuminating electromagnet and sensor circuitry was controlled using an automated XYZ scanner with an x-y measurement step size (ie magnetic image pixel size) of 100 microns. This probe was used to apply magnetic fields of various frequencies (DC to 1 kHz) and field strengths (5 mT to 100 mT) to ascertain a frequency and field range best suited to detecting 10 mm- and 11 mm-long longitudinal surface-breaking toe cracks in ground mild steel welds. A lift-off distance of <1 mm was controlled using a proximity laser and a z-direction motor module to autonomously control the probe lift-off and conform to sample geometry. This study found that an applied magnetic field with a frequency of 800 Hz and a field strength of 10 mT RMS was optimal under the constraint of power consumption, based on the ratio of MFL responses from the two flaws and the weld. It was found that other frequency field combinations had comparable or higher detection but were discounted as they had substantially higher power consumption.

Research on the method of measuring solution concentration based on the magneto-optical effect in permanent magnetic fields

2018 ◽  
Vol 40 (15) ◽  
pp. 4266-4272
Author(s):  
Xin-yu Gong ◽  
Yong-hua Lu ◽  
Le-gang Lin ◽  
Yong Diao
Keyword(s):  
Sodium Chloride ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Rotation Angle ◽  
Solution Concentration ◽  
New Device ◽  
Sodium Chloride Solutions ◽  
Magneto Optical Effect ◽  
Relative Errors ◽  
Magnetic Induction Intensity

In the magnetic fields built by neodymium–iron–boron (NdFeB) permanent magnets, the corresponding relationship among the concentration of sodium chloride solution, glucose solution and their magnetic rotation angles was researched in the temperature range 20–24°C. A helium–neon (He–Ne) laser with a wavelength of 632.8 nm was used in the experiment as light source. A new device is designed for assembling and adjusting the NdFeB permanent magnets. The permanent magnets have no thermal effect compared to an energized solenoid. The corresponding relationship between the concentration and rotation angle is calibrated by standard concentration gradient solutions. Then the concentration can be detected by using this relationship. The rotation angle of the solution is proportional to the concentration and increased with an increase of the magnetic induction intensity. In the magnetic cavity with Φ12 mm dimension, the rotation angles of sodium chloride solutions in the range 0–30 g/100 ml vary from 2.66° to 3.73° and their relative errors range from −1.39% to 1.34%. The rotation angles of glucose solutions in the range 0–50 g/100 ml vary from 2.66° to 26. 44° and their relative errors range from −0.55% to 1.00%. The uncertainty of this system is 0. 05°.

scholarly journals Calculation, design and manufacture of heteropolar magnetic levitation and linear drive systems of maglev transport

2021 ◽  
Vol 7 (2) ◽  
pp. 119-129
Author(s):  
Yuri F. Antonov
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Magnetic System ◽  
Synchronous Motor ◽  
Magnetic Systems ◽  
Linear Synchronous Motor ◽  
The Magnetic Field

Background: The methods of calculation and elements of the technology for creating heteropolar magnetic systems of levitation, lateral stabilization and a rotor-runner of a traction linear synchronous motor for the development of the transport technology "Russian Maglev" in order to achieve an increased levitation gap of 0.2 m, reduce the threshold speed of the exit vehicle in levitation mode up to 10 km/h. Aim: to develop methods for calculating and designing heteropolar poles from elementary permanent magnets, coils of the same type based on composite low-temperature superconductors and high-temperature tape superconductors of the second generation and a step-by-step technology for their production. Tasks: Creation of an on-board magnetic system of levitation and lateral stabilization, allowing to provide a levitation gap of 0.2 m, a threshold value of vehicle speed of 10 km/h when transition to levitation mode, to reduce stray magnetic fields to the level of the natural field of terrestrial magnetism of 50 T; Creation of a rotor-runner of a linear synchronous motor with an ironless stator with a power of 10 MW. Methods: outlines the main calculation methodologies: "analysis" and "synthesis". The "analysis" methodology is adopted in solving the "direct" calculation problem, when the configuration of the magnetic system is set and the magnetic field in the working area is calculated, and, if necessary, the stray magnetic fields. This methodology can be effectively applied if there is experience in creating magnetic systems. Otherwise, the "synthesis" methodology is applied, which is used in solving the "inverse" calculation problem, in which the picture of the distribution of the magnetic field in the working zone is set and the configuration of the magnetic system is found (synthesized). Results of the study performed: The parameters and characteristics of high-energy permanent magnets made of rare-earth metals, low-temperature and high-temperature superconducting winding materials have been analyzed, the choice of permanent magnets and superconducting winding material has been made; Calculations of the magnetic system of permanent magnets in the "Halbach assembly" and in the traditional assembly in a toothed ferromagnetic core have been carried out; Calculations of a track coil with a rectangular cross-section of the winding are performed; Methods for calculating and optimizing superconducting magnetic systems from a set of similar track modules have been developed; Conclusions: The results of the performed fundamental research will allow starting the calculation, design and construction of conveyor-main passenger and freight lines of maglev transport, as well as urban public transport.

Transmittal properties of a superconductor-ferromagnetic metamaterial subjected to magnetic fields generated by the permanent magnets

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542049
Author(s):  
H. Liu ◽  
X. T. Li ◽  
P. B. Zhou ◽  
H. Zhang ◽  
C. Yang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Transformation Optics ◽  
Optimal Structure ◽  
Magnetic Shielding ◽  
Static Magnetic Fields ◽  
Coaxial Cylinders ◽  
Geometrical Distribution ◽  
The Magnetic Field

Superconductor-ferromagnetic (FN) metamaterial with effective magnetic shielding and transmittal properties that allow the cloaking and transferring of static magnetic fields has been introduced. Most metamaterials consist of different arrangements of superconducting and ferromagnetic materials whose performance and feasibility mainly depend on the involved materials, their geometrical distribution and the permeability of each. In this paper, combining the method of transformation optics with the design of metamaterials, we experimentally demonstrated a superconductor-FM metamaterial system, composed of two coaxial cylinders of different lengths, to investigate the influence of the length and the properties of superconducting material on the magnetic transferring properties of the magnetic field produced by the permanent magnets. By comparing the transmittal magnetic field of different cases, the optimal structure has been ultimately achieved in terms of calculating the transmitted magnetic field ratios. The insights attained by the present study are aimed to provide useful implications for the design of wireless energy transmission and increasing the efficiency of magnetic transmittal devices.

Trapping Microparticles with Strongly Inhomogeneous Magnetic Fields

2003 ◽  
Vol 17 (17) ◽  
pp. 935-940 ◽  
Author(s):  
I. F. Lyuksyutov ◽  
A. Lyuksyutova ◽  
D. G. Naugle ◽  
K. D. D. Rathnayaka
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Self Assembly ◽  
Permanent Magnets ◽  
Polystyrene Microspheres ◽  
Buffer Solution ◽  
Magnetic Traps ◽  
Micron Size ◽  
Long Chains

By using micron size permanent magnets we have trapped directly single diamagnetic micron size polystyrene microspheres inside a buffer solution with a magnetic field and demonstrated self-assembly of several hundred microns long chains of microspheres in magnetic traps.

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