Magnetic Field Source Research Articles

Rod mangle rotation patterns for adjustable magnetic field generation

The use of adjustable magnetic field sources is becoming an indispensable necessity in numerous applications. In particular, permanent magnet assemblies, such as the rod mangle design, avoid the large power consumption and Joule heating problems present in electromagnets. In this work, we present a systematic 2D study of rod mangle configurations with different number of rods. We observe that the magnetic field homogeneity increases with the number of used rods and, for a sufficiently large number, the behavior of the assembly is similar to that of a perfect Halbach. Generally, the rotation of only one rod changes the direction and decreases the homogeneity and magnitude of the magnetic field. Nevertheless, the impact of such rotation reduces with the increase of the number of rods in the system. We also study how different rotation patterns influence the generated magnetic field and demonstrate how one can: (i) reduce the magnetic field magnitude rotating its direction; (ii) reduce the magnetic field magnitude keeping its direction constant; (iii) invert the magnetic field direction, after being reduced; or (iv) rotate the magnetic field direction keeping its magnitude constant. These results are similar to those obtained by a nested Halbach. In addition to the low cost, the results show that the mangle system is highly versatile, can be easily manipulated and, consequently, has a large application potential. The magnetic model was successfully validated with experimental systems of three and four rods.

Recent Progress of Biomimetic Tactile Sensing Technology Based on Magnetic Sensors.

In the past two decades, biomimetic tactile sensing technology has been a hot spot in academia. It has prospective applications in many fields such as medical treatment, health monitoring, robot tactile feedback, and human-machine interaction. With the rapid development of magnetic sensors, biomimetic tactile sensing technology based on magnetic sensors (which are called magnetic tactile sensors below) has been widely studied in recent years. In order to clarify the development status and application characteristics of magnetic tactile sensors, this paper firstly reviews the magnetic tactile sensors from three aspects: the types of magnetic sensors, the sources of magnetic field, and the structures of sensitive bodies used in magnetic tactile sensors. Secondly, the development of magnetic tactile sensors in four applications of robot precision grasping, texture characterization, flow velocity measurement, and medical treatment is introduced in detail. Finally, this paper analyzes technical difficulties and proposes prospective research directions for magnetic tactile sensors.

Magnetic Technologies and Green Solvents in Extraction and Separation of Bioactive Molecules Together with Biochemical Objects: Current Opportunities and Challenges

Currently, magnetic technology and green solvents are widely used in chemical engineering, environmental engineering and other fields as they are environmentally friendly, easy to operate and highly efficient. Moreover, a magnetic field has positive effect on many physicochemical processes. However, related new methods, materials, strategies and applications in separation science still need to be developed. In this review, a series of meaningful explorations of magnetic technologies for the separation of natural products and biologic objects, including magnetic ionic liquids and other magnetic solvents and fluids, magnetic nanoparticles and magnetic fields, and the development of magnetic separators were reviewed. Furthermore, the difficulties in the application and development of magnetic separation technology were discussed on the basis of comparison and data analysis, especially for the selection of magnetic materials and magnetic field sources. Finally, the progress in the development of magnetic separators was also elaborated for researchers, mainly including that of the new high-efficiency magnetic separator through multi-technology integration and the optimization of traditional magnetic separators, which help current techniques break through their bottleneck as a powerful driving force.

Entropy optimization analysis of Marangoni convective flow over a rotating disk moving vertically with an inclined magnetic field and nonuniform heat source

AbstractThe present study investigates the Marangoni convective fluid flow over a rotating disk with an inclined magnetic field and in the presence of a nonuniform heat source when the disk moves upward/downward with nonconstant velocity with the incorporation of the second law of thermodynamics. The Keller‐box method is applied to the reduced system of equations to draw graphical illustrations. The study of these illustrations to examine the effects of involved pertinent parameters, like, magnetic field, Marangoni number, angle of inclination, vertical disk movement parameter, heat source, and disk rotation, on velocity and temperature profiles, reveals some interesting findings. From the analysis, it can be concluded that the skin friction coefficient increases with more angle of inclination and the Marangoni number with the reverse trend in case of vertical disk movement. Also, the Marangoni number and vertical disk motion diminish the Nusselt number with a positive effect in the case of more angle of inclination. The rate of entropy generation is enhanced with the temperature ratio parameter while it diminishes with the inclined magnetic field of any strength. The current study in its reduced form is in excellent agreement with earlier published work to ensure the validity of the used numerical scheme.

Axial Dependence of the Longitudinal RF Magnetic Field and Plasma Parameters in an Inductive Plasma Source with an External Magnetic Field

Axial Dependence of the Longitudinal RF Magnetic Field and Plasma Parameters in an Inductive Plasma Source with an External Magnetic Field

On prescribed thermal distributions of bioconvection Williamson nanofluid transportion due to an extending sheet with non-Fourier flux and radiation

Bio-convection, Cattaneo-Christov, and thermal radiation fluxes are accompanied by mixed convection flow of Williamson nano-fluids. The dynamics of the fluid occur due to an extendable surface with two thermal boundary constraints; the prescribed heat flux and surface temperature. The objective of this exploration pertains to effective and efficient thermal distributions. Theoretical layout is formulated in the form of a partial differential format. In order to attain the numerical resolution of this non-linear formulation, similarity transforms are employed to modify them into ordinary differential forms. The computational code for the Runga-Kutta procedure is developed in a MATLAB script. The temperature of fluids enhances with mounting strength of prescribed heat flux, thermophoresis, thermal radiation, magnetic field, Brownian motion and heat source but it descends against thermal relaxation time. The speed of fluids undergoes retardation against exceeding inputs of Williamson parameter λ, parameters of porosity, and magnetic body force. The range of distinct parameters while computing graphically is taken as , , , , , , , , , , , , , , and .

Negative resistance and heat dissipation in superconducting wires in an ac magnetic field

A superconducting wire embedded into an alternating magnetic field H∝cos(ωt) can manifest negative resistance. At high enough frequencies ω≳1/τ, where τ is the characteristic time of magnetic relaxation, this effect becomes prominent. As a result, the energy obtained by the wire from a source of magnetic field (external coil) is transformed into the electromotive force which reduces the external voltage required to keep the transport current in the wire. We show that negative resistance appears in line with the out-of-phase regime of the ac magnetic response, and both are related with the crucial inhibition of the vortex dynamics by zero-field (annihilation) lines. We also find a universal (independent of frequency) expression for the mean voltage in a wire.

COILS – SOURCES OF HOMOGENEOUS MAGNETIC FIELDS

The sources of known homogeneous magnetic fields are used for calibration of instruments with which magnetic fields are measured and for various experiments and tests in electrical engineering, physics, medicine, biology and other scientific and technical areas. Depending on the value of the desired magnetic field, these can be permanent magnets or electromagnets and, more frequently, various coils (solenoids) fed by DC, AC or impulse current. The homogeneous magnetic fields attained by coils or coil systems widely vary from the microtesla order of magnitude with ordinary coils to the microtesla order of magnitude with superconductive coils.

Entropy analysis for MHD blood flow of hybrid nanoparticles (Au–Al 2 O 3 /blood) of different shapes through an irregular stenosed permeable walled artery under periodic body acceleration: Hemodynamical applications

The current study investigates the entropy generation for hybrid nanoparticles (Au–Al2O3/blood) through a vertical irregular stenosed artery in the presence of an external magnetic field, Joule heating, viscous dissipation, and heat source considering two-dimensional pulsatile blood flow and periodic body acceleration. The blood flow is assumed to be unsteady, laminar, viscous, and incompressible, and the artery walls are considered as permeable. The Reynolds temperature-dependent viscosity model is used to determine the variable viscosity effects. The governing momentum and energy equations are solved using Crank–Nicolson finite difference method by employing an appropriate coordinate transformation to build an accurate mesh using rectangular mesh units. Outcomes of the work are represented graphically for velocity, wall shear stress (WSS), volumetric flow rate, resistance impedance, temperature, heat transfer coefficient, entropy generation, and Bejan number, respectively. Also, the results are validated for velocity and temperature profiles for a given set of values of the dimensionless parameters. The entropy generation increases with rising values of shape parameter (n) up to a specific radius ( x 1 ∗ = 0.84 $x_1^*=0.84$ ) and then changes its behavior in the vicinity of the stenotic zone, in which entropy generation decreases with increasing values of shape parameter (n). The current findings may be helpful for biomedical scientists those are interested to investigate the treatment of various cardiovascular diseases (CVDs).

Exergoeconomic analysis of potential magnet configurations of a magnetic refrigerator operating at 4.2 K

This article compares the exergetic cost of cooling of an Adiabatic Demagnetization Refrigerator (ADR) providing 1 W of refrigeration at 4.2 K, with two different magnetic field sources: a Nb3Sn superconducting (SC) magnet and a NdFeB permanent magnet (PM) Halbach cylinder. The total cost of the system is assumed to be comprised of two components: the cost of the magnetocaloric material (MCM), which is a function of the total volume of the MCM, and the cost of the magnetic system, which depends on the MCM volume and the peak magnetic field. The exergetic cost of cooling for different values of mass (volume) of MCM and hot source temperatures are shown in the article, assuming a specific cost of the SC wire of 890$/kg, 3500$/kg for the MCM, and 100$/kg for the PM. The SC appear to be the most cost-effective solution for the system. However, if large temperatures spans are required between the hot source and the cold source PMs emerge as a better option.

Magnetic Poles: A Missing Manual

This work provides a missing manual needed to understand permanent magnets (also known as “hard” magnets), the only source of magnetic induction field B (units of teslas), often called the magnetic field, that students are familiar with when they confront magnetic force acting on moving charges. Students see this magnetic force in two forms:

Flux Pumping of Multiple Double-Loop Superconducting Structures for a Planar Magnetic Field Source

Flux Pumping of Multiple Double-Loop Superconducting Structures for a Planar Magnetic Field Source

Tunable magnetic field source for magnetic field imaging microscopy

In this work, we present a novel, compact, power efficient and variable magnetic field source design for magnetic field imaging microscopy. The device is based on a pair of diametrically magnetized permanent magnet cylinders with electro-mechanical rotation control and ferrite flux homogenizers. A Hall probe and NV centers in diamond are used to demonstrate a proof of concept of a proposed magnetic field setup and to characterize the homogeneity of the produced magnetic field on a micrometer scale. Numerical simulation results are compared with experimental results showing good agreement of the distribution of the magnetic field in the setup. As a result, a magnetic field source with a tunable field amplitude in the range from 1 mT to 222 mT is demonstrated, achieving a magnetic field homogeneity of 2 ppm/μm or 0.5 μT/μm at 222 mT in a 25 × 25 μm field of view.

MAGNETOELECTRIC VALVE MOTORS WITH TOOTHED MULTI-POLE WINDINGS BASED ON 6DVM 300

The paper considers valve motors with toothed windings with pole numbers 2, 4, 6, 8, the main dimensions of which correspond to the 6DVM 300 valve motor manufactured by JSC “Cheboksary electrical apparatus plant”. This approach allows us to evaluate the effect of the number of stator teeth on the electromagnetic moment and its harmonic composition. The three adjacent coils of the toothed windings in question belong to three different phases. The paper analyzes the MMF of the windings and magnets of the rotor. The distribution of magnetic induction in the gap, the EMF of the stator winding and the electromagnetic moment are found based on the method of the specific magnetic conductivity of the gap. It is shown that the MMF curve of the stator winding consists of two multipolar rectangles of unequal height and width. Due to the non-sinusoidal distribution of magnetic field sources and the jagged inhomogeneity of the air gap, the curves of the phase EMF of the stator winding are also significantly non-sinusoidal. It is found that with an increase in the number of poles (from 2 to 8 poles) of the stator winding, the maximum induction in the air gap decreases from level 1 to 0.75 Tl, the average value of the electromagnetic moment increases from 120 to 160 Nm, the amplitude of the phase EMF remains unchanged, and the maximum (height of the rectangle) of the MMF of the stator winding is reduced from 2000 to 500 A.

LOW FREQUENCY MAGNETIC FIELDS NEAR CHARGING STATIONS FOR ELECTRIC VEHICLES

Charging stations (CHS) for electric vehicles (EV) are considered as sources of local magnetic fields (MF). The MF created by the CHS depends mainly on the actual charging power and topology of the electrical components inside the CHS. MF are in technical practice represented by the effective value of the magnetic flux density BRMS. However, the complex view has to consider the resulting MF vector, its components and the corresponding frequency values of the components at the measurement point and also their corresponding time development. The paper presents measurements of MF near the CHS that were performed with the VEMA-04 series magnetometer and 38 kW power drawn from the CHS. The parameters of the magnetic fields were evaluated in both the time and the frequency domains. The aim of this analysis is to point out that evaluating only simple effective value BRMS of MF is not sufficient.

A calibration standard for low-frequency environmental magnetic field meters

In this paper, we present the establishment of a magnetic flux density standard in the national calibration laboratory in Croatia. A single-layer Helmholtz coil was constructed as a magnetic field source at frequencies from 25 Hz to 100 kHz to calibrate magnetic field meters up to field limits for occupational exposure. First, the calibration error margin was determined for probes up to 100 cm2 of the cross-sectional area with respect to the predefined calibration volume inside the coil. Next, the equivalent electrical model of the assembled standard was parameterized as a multiple resonance circuit to estimate the correction of the reference field with frequency. Finally, the calculated correction was experimentally verified using a single-turn induction loop with an amplifier. The resulting uncertainty budget of the standard confirms the laboratory's capability to calibrate environmental magnetometers with the best relative uncertainty of 0.8 %.

The Influence of Magnetic Composite Capsule Structure and Size on Their Trapping Efficiency in the Flow.

A promising approach to targeted drug delivery is the remote control of magnetically sensitive objects using an external magnetic field source. This method can assist in the accumulation of magnetic carriers in the affected area for local drug delivery, thus providing magnetic nanoparticles for MRI contrast and magnetic hyperthermia, as well as the magnetic separation of objects of interest from the bloodstream and liquid biopsy samples. The possibility of magnetic objects’ capture in the flow is determined by the ratio of the magnetic field strength and the force of viscous resistance. Thus, the capturing ability is limited by the objects’ magnetic properties, size, and flow rate. Despite the importance of a thorough investigation of this process to prove the concept of magnetically controlled drug delivery, it has not been sufficiently investigated. Here, we studied the efficiency of polyelectrolyte capsules’ capture by the external magnetic field source depending on their size, the magnetic nanoparticle payload, and the suspension’s flow rate. Additionally, we estimated the possibility of magnetically trapping cells containing magnetic capsules in flow and evaluated cells’ membrane integrity after that. These results are required to prove the possibility of the magnetically controlled delivery of the encapsulated medicine to the affected area with its subsequent retention, as well as the capability to capture magnetically labeled cells in flow.

Unsteady Radiative Maxwell Fluid Flow over an Expanding Sheet with Sodium Alginate Water-Based Copper-Graphene Oxide Hybrid Nanomaterial: An Application to Solar Aircraft

The primary heat source from the sunlight is solar energy, which is used in photovoltaic panels, solar power plates, photovoltaic streetlights, and solar-based hybrid nanocomposites. A hybrid nanofluid is traversing an expanding sheet in this investigation. Maxwell fluid stream with two nanoparticles is going towards a trough with a parabolic form and is situated within the solar aircraft wing to investigate the phenomena of heat transfer rate. The term solar thermal radiation was introduced to describe heat transfer occurrence. The effectiveness of heat transmission from airplane wings is assessed by taking into account unique phenomena such as magnetic field and heat source. The bvp4c procedure was applied to quantitatively explain the energy and motion equations with MATLAB software. The copper (Cu) and graphene oxide (GO) nanosolid particles are mixed with sodium alginate (SA), a common liquid, to form the nanosolid particles. Numerous control variables are thoroughly examined, including temperature, shear stress, motion, friction component, and Nusselt number. The skin-friction coefficient upsurges with a growing magnetic impression. The upsurge in Deborah number reduces the skin-friction coefficient. The heat source impression declines the heat transport rate but upsurges the skin-friction coefficient. The skin-friction coefficient and heat transport rate increase with growing magnetic impression. When it comes to heat transfer analysis, hybrid nanofluid efficiency is substantially superior to that of regular nanofluid.

Non-invasive blood glucose sensing by machine learning of optic fiber-based speckle pattern variation.

.SignificanceThe ability to perform frequent non-invasive monitoring of glucose in the bloodstream is very applicable for diabetic patients.AimWe experimentally verified a non-invasive multimode fiber-based technique for sensing glucose concentration in the bloodstream by extracting and analyzing the collected speckle patterns.ApproachThe proposed sensor consists of a laser source, digital camera, computer, multimode fiber, and alternating current (AC) generated magnetic field source. The experiments were performed using a covered (with cladding and jacket) and uncovered (without cladding and jacket) multimode fiber touching the skin under a magnetic field and without it. The subject’s finger was placed on a fiber to detect the glucose concentration. The method tracks variations in the speckle patterns due to light interaction with the bloodstream affected by blood glucose.ResultsThe uncovered fiber placed above the finger under the AC magnetic field (150 G) at 140 Hz was found to have a lock-in amplification role, improving the glucose detection precision. The application of the machine learning algorithms in preprocessed speckle pattern data increase glucose measurement accuracy. Classification of the speckle patterns for uncovered fiber under the AC magnetic field allowed for detection of the blood glucose with high accuracy for all tested subjects compared with other tested configurations.ConclusionsThe proposed technique was theoretically analyzed and experimentally validated in this work. The results were verified by the traditional finger-prick method, which was also used for classification as a conventional reference marker of blood glucose levels. The main goal of the proposed technique was to develop a non-invasive, low-cost blood glucose sensor for easy use by humans.

Modeling and simulation of smart magnetic self-assembled nanomicelle trajectories in an internal thoracic artery flow for breast cancer therapy.

Magnetic drug targeting (MDT) is one of the most modern techniques in cancer therapy for its ability to reduce the side effects of chemotherapy experienced by systemic drug administration. In this study, a comprehensive mathematical model has been developed to predict the drug particle trajectories of anticancer dasatinib magnetic nanomicelles (DAS-MNM) released in an internal thoracic artery (ITA) blood flow for breast cancer therapy using an external magnetic field. Several factors are investigated in regard to the efficiency of MDT through the ITA, including magnetic field strength (MFS), relative magnetic permeability, magnet size, drug particle size, and initial position of drug particle. The drug particle trajectory results confirmed the successful MDT using an external magnetic field with a capture efficiency of more than 90%. This was achieved by employing a wide range of particle sizes of DAS-MNM close to the external magnetic field source at the arterial wall than in other positions. Moreover, the results showed that the number of trapped particles increased with increasing both MFS and drug particle diameter within the target tissue, while the drug particle permeability did not have a considerable effect on the particle retention. In addition, for achieving a successful drug/cargo delivery through the arteries, the magnetic field, the particle size, and the initial release locations should be adjusted simultaneously. The present work offers insights into the critical factors in MDT with a significant impact on breast cancer therapy, tissue engineering, and regenerative medicine. Magnetic drug targeting model of anticancer dasatinib magnetic nanomicelles (DAS-MNM) released in an internal thoracic artery blood flow for breast cancer therapy.