Magnetic Field Source Research Articles

Noninvasive blood glucose sensing by secondary speckle pattern artificial intelligence analyses.

Diabetes is a prevalent disease worldwide that can cause severe health problems. Accurate blood glucose detection is crucial for diabetes management, and noninvasive methods can be more convenient and less painful than traditional finger-prick methods. We aim to report a noncontact speckle-based blood glucose measurement system that utilizes artificial intelligence (AI) data processing to improve glucose detection accuracy. The study also explores the influence of an alternating current (AC) induced magnetic field on the sensitivity and selectivity of blood glucose detection. The proposed blood glucose sensor consists of a digital camera, an AC-generated magnetic field source, a laser illuminating the subject's finger, and a computer. A magnetic field is applied to the finger, and a camera records the speckle patterns generated by the laser light reflected from the finger. The acquired video data are preprocessed for machine learning (ML) and deep neural networks (DNNs) to classify blood plasma glucose levels. The standard finger-prick method is used as a reference for blood glucose level classification. The study found that the noncontact speckle-based blood glucose measurement system with AI data processing allows for the detection of blood plasma glucose levels with high accuracy. The ML approach gives better results than the tested DNNs as the proposed data preprocessing is highly selective and efficient. The proposed noncontact blood glucose sensing mechanism utilizing AI data processing and a magnetic field can potentially improve glucose detection accuracy, making it more convenient and less painful for patients. The system also allows for inexpensive blood glucose sensing mechanisms and fast blood glucose screening. The results suggest that noninvasive methods can improve blood glucose detection accuracy, which can have significant implications for diabetes management. Investigations involving representative sampling data, including subjects of different ages, gender, race, and health status, could allow for further improvement.

Laser powder bed fusion of anisotropic Nd-Fe-B bonded magnets utilizing an in-situ mechanical alignment approach

Nd-Fe-B bonded magnets are an important class of permanent magnets, employed in many technological sectors. Additive Manufacturing (AM) enables the fabrication of net-shape bonded magnets with complex geometries, allowing to tailor their magnetic stray field specifically for a given application. A crucial challenge is the production of magnetically anisotropic components. Approaches presented in the literature up to now required a post-printing procedure or the complex integration of a magnetic field source into the AM process. Here, we present a technique to fabricate anisotropic bonded magnets via Laser Powder Bed Fusion (LPBF) by utilizing the mechanical alignment of anisotropic particles in a single step, without the need for a magnetic field source. Anisotropic bonded magnets were fabricated using a mixture of anisotropic Nd-Fe-B powder (MQA-38–14) and polyamide-12 (PA12). This magnetic powder consists of ellipsoidal particles, where the easy magnetization axis is distributed perpendicular to their longest side, and the mean aspect ratio of 3:1 can be exploited to generate magnetic texture. Depending on the particle size used as feedstock, the degree of alignment (<cosθ>) can be tailored to a maximum of <cosθ> = 0.78. The fabricated anisotropic bonded magnets exhibited a maximum remanence of Jr = 377 mT and an energy product of (BH)max = 28.6 kJ/m3, respectively.

Shape and Stability of a Local Heat-Transfer Magnetofluid Coating on a Plate

Purpose. Investigate the shape and stability of a magnetic fluid coating on a flat surface in a non-uniform magnetic field of a permanent magnet.Methods. Magnetic fluids based on transformer oil MMT-44 and MMT-21 with saturation magnetization of 43.8 and 21.2 kA/m, respectively, were used in the experiments. A magnetic-fluid coating was formed on the surface of horizontal and vertical non-magnetic plates in a locally inhomogeneous magnetic field of permanent magnets. The source of the inhomogeneous magnetic field is a system of two rectangular magnets. The size of the magnetic system is 40×12×10 mm. The maximum values of the magnetic field strength and gradient reach 180 kA/m and 8∙104 kA/m2, respectively. The shape and stability of a sessile and suspended magnetic fluid coating were studied for various plate orientations.Results. The shape and stability of the magnetic fluid coating on horizontal and vertical plates are studied. The experimental dependences of the height and length of the coating on the volume of the magnetic fluid are established. It is established that the coating can have a certain maximum volume. When this volume is exceeded, the liquid spreads over the surface of the plate or a part of the liquid volume is separated. The limiting volume of the coating is determined by the magnetic characteristics of the ferrofluid and the magnetic field.Conclusion. The possibility of forming a sessile and suspended local magnetic fluid coating on horizontal and vertical plates is established. The height and length of the magnetic fluid coating on the plate depend on the volume of the magnetic fluid, as well as on the characteristics of the magnetic system and the magnetization of the magnetic fluid. The results obtained can be used in the formation of magnetic fluid coatings of cooled sections of heated surfaces.

Ferromagnetism of concrete

Studying the intrinsic properties of concrete is essential for addressing various aspects of concrete structure design, material selection, and sustainability. In this study, a suspended strong magnetic torsion balance device was designed and constructed to investigate the ferromagnetic properties of concrete specimens and their constituent materials. It was found that sand and cement generally exhibit ferromagnetic properties, while aggregates do not possess ferromagnetic properties. Analysis using powder X-ray diffraction (XRD) and chemical experiments confirmed that the ferromagnetic material in sand and cement is elemental iron. A simplified calculation formula for the magnetic force between concrete specimens and an external magnetic field was derived. Three sets of specimens were designed and fabricated for experimental exploration of ferromagnetic properties and magnetic force measurements. The experimental results demonstrate that plain concrete possesses measurable ferromagnetic properties. The magnetic force of concrete initially experiences a rapid decay followed by a gradual leveling off as the distance (from the magnetic field source to the concrete surface) increases. The decay rate approximately follows a fourth-power relationship with distance. Under a loading condition with an applied magnetic field intensity of 0.2 T, the optimal measurement range for ferromagnetic force in concrete is between 0.02 m and 0.05 m.

Orientation degrees in Dy123 powders by using Linear-drive type Modulated Rotating Magnetic Field system

Bi-axial magnetic alignment of DyBa2Cu3Oy (y ~ 7) grains with high in-plane orientation degrees has been achieved using only permanent magnets as magnetic field sources. When compared to electromagnets such as a superconducting magnet, arrayed magnets offer a lower cost and greater versatility as magnetic field sources for magnetic alignment. In this study, permanent magnets were arranged in such a way that they were able to create a rotating magnetic field with a strength of 0.8 T-class. This helps with the magnetic alignment of functional materials like cuprate superconductors.

Magnetic Levitation System Prototype Using Proportional-Integral-Derivative Control

Magnetic levitation is a phenomenon of levitation objects by using a magnetic field to defy gravity. Magnetic levitation is an interesting research topic widely used in industry or transportation such as magnetic levitation trains, conveyors, lifts, and many more. In general, magnetic levitation can be realized by regulating the current as a magnetic field source. However, due to the normally unstable power supply source, results in magnetic field instability. Therefore, a magnetic field control system is needed to stabilize the magnetic levitation system. In this study, a magnetic lifting system has been developed using the Proportional-Integral-Derivative (PID) control method and hall effect sensor. The result shows that by using the PID controller, the magnetic object successfully floated stably at the reference point form 1.4 cm to 6.5 cm with an error ± 0.02 cm and overshoot 0.2 cm, if without using PID, oscillations occur with an error rate of ± 0.1 cm and overshoot of 0.6 cm.

Efficiency of ferromagnetic shielding of superconducting coils of high-speed maglev crew

Background: Magnetic levitation transport with combined traction, suspension and guidance systems based on superconducting coils (SCC) allows reaching speeds of up to 500600 km/h with a very significant (up to 150200 mm) air gap, which is an important factor in ensuring the safety of high-speed transportation. However, SCC are a source of strong external magnetic fields, which, in conditions of limited crew dimensions, can have a harmful effect on both passengers and on-board auxiliary equipment.&#x0D; Aim: to analyze the external magnetic fields of the SCC systems for traction, suspension and direction of maglev vehicles and the effectiveness of ferromagnetic screens as a means of ensuring the electromagnetic safety of passengers and the electromagnetic compatibility of the SCC with other onboard equipment.&#x0D; Materials and methods: to achieve this goal, methods of analytical and numerical modeling of the magnetic fields of the SCC using modern software packages were used. As a prototype of the combined magnetic system of traction, suspension and direction, the system of the MLX-L0 maglev vehicle, which is undergoing pilot commercial operation at the Yamanashi test line (Japan), was adopted.&#x0D; Results: it is shown that the value of the external magnetic fields of the SCC of the traction and guiding systems in the passenger cabin of the prototype crew exceeds the maximum permissible levels established by domestic and foreign regulatory documents, both without shielding and with passive shielding with flat steel sheets.&#x0D; Conclusion: passive shielding of the SCC with steel sheets, including multilayer ones, does not provide the required reduction in the level of external magnetic fields for a given vehicle dimensions.

Investigation of the Operating Regimes of Penning Ion Sources in Inhomogeneous Magnetic Fields

Investigation of the Operating Regimes of Penning Ion Sources in Inhomogeneous Magnetic Fields

Numerical study of hybridized Williamson nanofluid flow with TC4 and Nichrome over an extending surface

Abstract Enhancement in thermal distribution of Williamson hybrid nanofluid flow is articulated in this research. Nichrome and TC4 nanoparticles are homogenously diffused in the water, which is the base fluid. An elongating surface holds the flow and thermal transition phenomenon in the existence of uniform sources of magnetic field and heat radiation. The boundary of wall obeys a suction and slip condition. The formulation for physical conservation laws is made as a system of partial differential equations. For the solution purpose, their boundary-value problem is transmuted into the ordinary differential form. Then, Matlab code involving Runge–Kutta procedure is run to compute the variation in velocity as well as temperature profiles under impacts of the controlling factors. The comparative computations are made for two cases: nanofluids ( TC 4 + water ) \left({\rm{TC}}4+{\rm{water}}) and hybrid nanofluids ( TC 4 , Nichrome + water ) \left({\rm{TC}}4,{\rm{Nichrome}}+{\rm{water}}) . The heat for that hybrid nanofluid case is larger than that for the nanofluids. The velocity curve is decreased against increasing magnetic field strength and Williamson parameter. Enhancement in thermal distribution is observed with increasing concentration ϕ 2 {\phi }_{2} of Nichrome.

Estimation of the Spatial and Temporal Distribution of Magnetic Fields around Overhead Power Lines—A Case Study

Due to the growing number, diversity and spreading of magnetic field sources, an increasing need to determine the field levels of human exposure has arisen. Some of the most encountered sources are the overhead power lines (OPL) and the determination of spatial and temporal variation of the magnetic fields produced by OPLs is a challenge. In this paper a hybrid method for the estimation of the temporal and spatial distribution of the magnetic flux density B caused by OPLs, based on experimental measurements and on numerical and analytical simulations, is presented. Thus, using a small number of simultaneous spot measurements correlated with a long-term survey, maps of the magnetic flux density distribution on extended areas are established, for several time instances. The proposed method is verified using two sets of different measurements and the results obtained through simulation. The difference between the estimated and simulated values of B is under 5.5%, which is considered acceptable considering that B spans over a large set of values (724 nT ÷ 1375 nT) in the location of the long-term survey procedure. The possibilities and limitations of the proposed method are discussed.

A case study of intrathecal baclofen pump motor shutdown secondary to the effect of the magnetic field created by a personal digital tablet and magnetic cover.

We present the case of a post-traumatic C6 AIS A tetraplegic patient with spasticity treated with an intrathecal baclofen pump (ITB), who noticed a transient increase in his spasticity each time he used a digital tablet (Ipad®) protected by a magnetic shell placed on his abdomen. Telemetry confirmed transient motor shutdown responsible for withdrawal symptoms each time the tablet was used. Symptoms resolved after the removal of the protective shell. Effects of magnetic fields like magnetic resonance imaging (MRI) are known to stall the pump rotor, which recover at the end of MRI. Other sources of magnetic fields like laptops or new smartphones with magnet charging technology may also interfere with implanted devices. We therefore recommend patients to avoid close contact of magnetic devices with the intrathecal baclofen pump. More robust studies are warranted to assess the effect of the new magnetic technologies on the function of intrathecal pumps.

QCD thermodynamics and neutral pion in a uniform magnetic field: Finite volume effects

We address finite volume effects of lattice QCD calculations in background magnetic fields. Using chiral perturbation theory at next-to-leading order, volume effects are calculated for thermodynamic quantities: the chiral condensate, pressure anisotropy, and magnetization. The neutral pion effective action in a finite volume is additionally derived. For these charge neutral observables, volume and source averaging are shown to capitalize on magnetic periodicity, which is the remnant translational invariance of the finite-volume theory. For a fixed magnetic field strength, certain volume and source averaged quantities are independent of the size of the lattice transverse to the magnetic field. Despite this simplifying feature, finite volume corrections to the magnetic field dependence of the chiral condensate and neutral pion magnetic polarizability can be non-negligible. The pressure anisotropy at fixed magnetic flux, moreover, appears acutely sensitive to the lattice volume.

Influence and remedial measures of missing test data on magnetic field source location of underwater vehicle

Due to the incomplete data collected, it will increase the difficulty of inversion location in the field source inversion of the static magnetic field data of underwater vehicles. Therefore, it is very necessary to study the influence of data loss on the static magnetic source location of underwater vehicles and the field source location for timely remedy of missing data. In this paper, the static magnetic equivalent source model of underwater vehicle was established. Then the inversion positioning algorithm was used to locate the magnetic field source of the underwater vehicle obtained from the test, and the influence of the location result under the incomplete data information was analyzed. We used deleting method, linear interpolation method and sliding filling method to populate the data to fill the remedy of missing data. Using the localization algorithm to carried out the inversion location of source, then we took the location of source inversion and the size of the magnetic dipole moment to the ellipsoid model to get fitting curve of magnetic field. The simulation curve of contrast verification test data with experimental data and the lack of remedial method was feasible. The results show that the missing data can not be ignored for the location of the underwater vehicle’s magnetic field source, and the data pairs filled with missing data can be effectively located for the equivalent static magnetic field source of the underwater vehicle through using deletion method, linear interpolation method and sliding filling method.

The Study of the Lithospheric Magnetic Field over Xinjiang and Tibet Areas Based on Ground, Airborne, and Satellite Data

Combined with the ground, airborne, and CHAMP satellite data, the lithospheric field over Xinjiang and Tibet is modeled through the three-dimensional Surface Spline (3DSS) model, Regional Spherical Harmonic Analysis (RSHA) model, and CHAOS-7.11 model. Then, we compare the results with the original measuring data, NGDC720, LCS-1, and the newest SHA model with the degree to 1000 (SHA1000). Moreover, the error estimation and the geological analysis are carried out, and we investigate the possible correspondence between the lithospheric field and the surface heat flow. The results show that the 3DSS model can better describe the detailed distribution of the lithospheric field after comparing it with other models. Some new features are reflected, particularly in the areas of Southern Xinjiang and Tibet, such as a positive anomaly stripe in the southwest, its neighboring Tashkurgan–Hotan–Cele–Minfeng–Qiemo–Ruoqiang belt, and the middle edge of the Kunlun Mountains. The stripe, in terms of rock composition, has a shallow magnetic field source and is related to magnetic intrusions; the lithospheric field in Tibet is weak. Additionally, when the heat flow distribution is compared to our results, there is a good consistency between a positive stripe of heat flow and a positive stripe of the lithospheric field in southern Tibet. The large heat flow values may be related to the shallow Curie surface, which shows that demagnetization is happening close to the surface. However, more of a ferromagnetic mineral, Titanium magnetite, is found there.

Wind-fed GRMHD simulations of Sagittarius A*: tilt and alignment of jets and accretion discs, electron thermodynamics, and multiscale modelling of the rotation measure

ABSTRACTWind-fed models offer a unique way to form predictive models of the accretion flow surrounding Sagittarius A*. We present 3D wind-fed magnetohydrodynamic (MHD) and general relativistic magnetohydrodynamic (GRMHD) simulations spanning the entire dynamic range of accretion from parsec scales to the event horizon. We expand on previous work by including non-zero black hole spin and dynamically evolved electron thermodynamics. Initial conditions for these simulations are generated from simulations of the observed Wolf–Rayet stellar winds in the Galactic Centre. The resulting flow tends to be highly magnetized (β ≈ 2) with an ∼r−1 density profile independent of the strength of magnetic fields in the winds. Our simulations reach the magnetically arrested disc (MAD) state for some, but not all cases. In tilted flows, standard and normal evolution (SANE) jets tend to align with the angular momentum of the gas at large scales, even if that direction is perpendicular to the black hole spin axis. Conversely, MAD jets tend to align with the black hole spin axis. The gas angular momentum shows similar behaviour: SANE flows tend to only partially align while MAD flows tend to fully align. With a limited number of dynamical free parameters, our models can produce accretion rates, 230 GHz flux, and unresolved linear polarization fractions roughly consistent with observations for several choices of electron heating fraction. Absent another source of large-scale magnetic field, winds with a higher degree of magnetization (e.g. where the magnetic pressure is 1/100 of the ram pressure in the winds) may be required to get a sufficiently large rotation measure with consistent sign.

Scattering of light in thin magnetized envelopes – II

ABSTRACT We consider optically thin spherical stellar envelopes with dipole magnetic field. The source of magnetic dipole field is assumed point like and emits the non-polarized monochromatic radiation. This paper carry on the previous paper of authors, where the general theory is presented and the circular polarization of scattered radiation is calculated for small values of magnetic fields corresponding to parameter x ≪ 1 (x = ωB/ω ≃ 0.933 × 10−8λ(μm)B(G)). The Stokes parameters of scattered radiation mutually transform into each other due to interference. Here we obtained the explicit formulas describing the transformation of all Stokes parameters for any value of parameter x. The qualitative discussion of these formulas is presented. These formulas show that for x ∼ 1 the transformation leads to large variations of all Stokes parameters. The linear and circular polarizations acquire oscillating dependence on the propagation path. For x ≫ 1 the single scattered radiation has very small circular polarization of the order ∼1/x ≪ 1 and large linear polarization. In this case the transformation gives rise to additional value of observed circular polarization, which is proportional to initial single scattered value. The observed linear polarization acquires small inclination angle relative to the plane ‘line of sight–direction of magnetic dipole’ due to existence of small circular polarization. The Stokes parameters of single scattered radiation from all envelope without taking into account the interference effects are given for x ≫ 1.

Coherence and realism in the Aharonov-Bohm effect

The Aharonov-Bohm effect is a fundamental topological phenomenon with a wide range of applications. It consists of a charge encircling a region with a magnetic flux in a superposition of wave packets having their relative phase affected by the flux. In this work we analyze this effect using an entropic measure known as realism, originally introduced as a quantifier of a system's degree of reality and mathematically related to notions of global and local quantum coherence. More precisely, we look for observables that lead to gauge-invariant realism associated with the charge before it completes its loop. We find that the realism of these operators has a sudden change when the line connecting the center of both wave packets crosses the solenoid. Moreover, we consider the case of a quantized magnetic-field source, pointing out similarities and differences between the two cases. Finally, we discuss some consequences of these results.

Mixed Convection in a Double Lid-Driven Wavy Shaped Cavity Filled with Nanofluid Subject to Magnetic Field and Internal Heat Source

A numerical investigation is carried out to analyze the impacts of internal heat source size, solid concentration of nanoparticles, magnetic field, and Richardson number on flow characteristics in an oppositely directed lid-driven wavy-shaped enclosure. The left and right vertical walls of the enclosure are cooled isothermally and moving with fixed velocity in upward and downward directions, respectively. The bottom wall is wavy shaped and isothermally cooled as the vertical walls while the top wall is kept adiabatic. A rectangular heater is placed horizontally in the center of the cavity. The physical problems are characterized by 2D governing partial differential equations accompanying proper boundary conditions and are discretized using Galerkin’s finite element formulation. The study is executed by analyzing different ranges of geometrical and physical parameters, namely, internal heat source length 0.2 ≤ CH ≤ 0.6 , solid concentration of nanoparticles 0 ≤ φ ≤ 0.09 , Hartmann’s number 0 ≤ Ha ≤ 70 , and Richardson’s number 0.1 ≤ Ri ≤ 10 . The results indicate that the overall heat transfer rate declines with the increasing length of internal heat source. The presence and rising values of solid concentration of nanoparticles cause the augmentation of heat transfer whereas the magnetic field has a negative influence and the Richardson number has a positive influence on heat transfer.

Significance of Nanoparticle Radius and Gravity Modulation on Dynamics of Nanofluid over Stretched Surface via Finite Element Simulation: The Case of Water-Based Copper Nanoparticles

This communication studies the importance of varying the radius Dp of Copper nanoparticles for microgravity-modulated mixed convection in micropolar nanofluid flux under an inclined surface subject magnetic field and heat source. In the current era, extremely pervasive modernized technical implementations have drawn attention to free convection governed by g-jitter force connected with microgravity. Therefore, fixed inter-spacing of nanoparticles and effects of g-jitter on the inclined surface are taken into consideration. A mathematical formulation based on conservation principles was non-dimensionalized by enforcement of similarity transformation, yielding a related set of ODEs. The convective non-linearity and coupling, an FE discretization, was implemented and executed on the Matlab platform. The numerical process’ credibility was ensured for its acceptable adoption with the defined outcomes. Then, the computational endeavor was continued to elucidate the impacts of various inputs of Dp, the amplitude of modulation ϵ, material parameter β, mixed convection parameter λ, inclination angle γ, and magnetic parameter M. The enlarging size of nanoparticles accelerated the nanofluid flow due to the depreciation of viscosity and receded the fluid temperature by reducing the surface area for heat transportation. The modulated Nusselt number, couple stress, and skin friction coefficient are significantly affected by the variation of Dp, M, β, λ, and ϵ. These results would benefit experts dealing with upper space transportation and materials’ performance, such as the effectualness of chemical catalytic reactors and crystals.

Permanent Magnet Electrodynamic Suspensions Applied to MAGLEV Transportation Systems: A Review

This article reviews permanent magnet electrodynamic suspensions (PM-EDSs) used in ground transportation systems, such as Magnetic Levitation (MAGLEV) trains. The different suspension topologies are first presented, considering separately their two main components, namely the track and the magnetic field source. Beyond that, a phenomenological explanation of the evolution with the speed of the drag and levitation forces is provided, depending on the track topology. The models aimed at predicting the behavior and performance of the suspension are then detailed, classifying them according to whether they are global or local. Finally, the main experimental setups developed to validate PM-EDSs are described.