High-intensity Magnetic Field Research Articles

Magnetic field effect on apparent viscosity reducing of different crude oils at low temperature

The viscosity of crude oil is extremely high at low temperature and transporting crude oil through pipelines consumes a lot of energy. Reducing the viscosity of crude oil can save a large amount of energy and have significant economic benefits. In this study, the viscosity reduction effects of four types of crude oils by applying an external magnetic field at 5 °C was studied. Experimental results show that at low temperature, high intensity magnetic field can not only reduce the viscosity of high waxy crude oil, but also decrease the viscosity of heavy oil with high content of heavy components. When the maximum magnetic flux density is 1T, the maximum viscosity reduction rates of the four crude oils was 13.29%, 26.88%, 14.44% and 18.72%, respectively. An empirical formula was proposed to describe the variation of crude oil viscosity with magnetic field and to predict the existence of viscosity reduction limit. The mechanism of viscosity change is ascribed to the change of microscopic aggregation of suspended particles in oil. The thickening phenomenon of some crude oils under magnetic field is due to the polarized chains of aggregation crosses the upper and lower plates. This research shows that it has great potentials of utilize magnetic field viscosity reduction to help crude oil pipelines transportation at low temperature.

Conjugate MHD natural convection in a square cavity with a non-uniform heat source thick solid partition

This paper aims to investigate the effect of a non-uniform internal volumetric energy generation on the conjugate MHD natural convection in a square cavity filled by an electrically conducting fluid. The uniform magnetic field is applied horizontally; the two horizontal and vertical left walls are thermally insulated, whereas the right vertical wall is kept at constant cold temperature. The governing conservation equations are solved numerically using an in house program based on the finite-volume method and the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The effects of internal Rayleigh, Hartmann and Prandtl numbers, thermal conductivity ratio, inclination angle of the cavity, and the thickness of heat source partition are discussed. The obtained results show that regardless of Kr , α and Δ, an almost pure conduction state is observed for low RaI without MHD and for high RaI with MHD at high magnetic field intensity.

Development of a RELAP5/MOD3.3 Module for MHD Pressure Drop Analysis in Liquid Metals Loops: Verification and Validation

Magnetohydrodynamic (MHD) phenomena, due to the interaction between a magnetic field and a moving electro-conductive fluid, are crucial for the design of magnetic-confinement fusion reactors and, specifically, for the design of the breeding blanket concepts that adopt liquid metals (LMs) as working fluids. Computational tools are employed to lead fusion-relevant physical analysis, but a dedicated MHD code able to simulate all the phenomena involved in a blanket is still not available and there is a dearth of systems code featuring MHD modelling capabilities. In this paper, models to predict both 2D and 3D MHD pressure drop, derived by experimental and numerical works, have been implemented in the thermal-hydraulic system code RELAP5/MOD3.3 (RELAP5). The verification and validation procedure of the MHD module involves the comparison of the results obtained by the code with those of direct numerical simulation tools and data obtained by experimental works. As relevant examples, RELAP5 is used to recreate the results obtained by the analysis of two test blanket modules: Lithium Lead Ceramic Breeder and Helium-Cooled Lithium Lead. The novel MHD subroutines are proven reliable in the prediction of the pressure drop for both simple and complex geometries related to LM circuits at high magnetic field intensity (error range ±10%).

Physiotherapy in the Сomplex Rehabilitation of Children with Anorectal Malformations: Systematic Review

Medical rehabilitation is an integral part of the treatment for surgical patients. Regarding pediatric patients with anorectal malformations, the success of the result of surgical treatment is mainly a correctly selected rehabilitation program, including methods of individual physiotherapy. Disturbances of intestinal transit, such as chronic constipation and anal incontinence, according to the world literature, occur in the study group in up to 30% of cases. According to the social significance of constipation and anal incontinence, the psychological aspects, the disabling component, children with anorectal malformations need early and long-term rehabilitation, adapted to their needs. At the moment, there are regulatory documents describing the principles of medical rehabilitation of children, its main characteristics, however, there are no protocols for the use of physiotherapy methods regarding the manifestations of colon transit disorders. Aim. Analysis of modern literature data on physiotherapeutic methods of rehabilitation of children with anorectal malformations. Material and methods. After determining the research criteria, a basic literature review using Web of Science, PubMed, electronic library was conducted, as a result 186 articles were selected that met the search criteria. After the initial assessment, 10 full-text articles were accepted for the analysis. Results. We have assessed the opportunity and mechanisms of the therapeutic action of sacral stimulation and tibial neuromodulation, the effect of various types of currents and a high-intensity magnetic field on the muscles of the complex, studied the possibility and results of using biofeedback therapy in children with colon transit disorders after operations on the anorectal body area in 421 children in 10 studies. Conclusion. Based on the results of scientific research, a range of physiotherapy methods have been established that are effective in relation to rehabilitation measures in children with anorectal malformations.

Workshop 2: Transcranial Magnetic Stimulation (TMS) WS2.1. Introduction to TMS

Transcranial magnetic stimulation (TMS) transports a short (about 100 µs) high intensity (∼ 2 Tesla) magnetic field painless through the skull into the brain and induces an electric current flow. This in turn excites neurons or fiber tracts. TMS can only induce tangential current flow. Its intensity declines exponentially; thus mainly cortical areas closed to the surface are targeted. The best available data are those obtained at the motor cortex (M1). M1 stimulation allows easy quantification of effects by recording electromyographic muscle activity. When stimulating the visual cortex phosphenes can be induced. Computational models allocate the lowest threshold elements into terminals of the axon collaterals. The dependence of threshold and polarization on spatial and temporal stimulation parameters are strongly affected by morphological features of the axonal arbor, including myelination, diameter, and branching. The thresholds for current flow are directionally sensitive, with lower threshold from the back to the front as vice versa. Intensity dependent a D-wave and several I-waves with 1.5 ms intervals are induced, which can be recorded in man invasively at the cervical spinal cord. In psychology it allows to induce short virtual lesions which provide data on cortical functions arising in the area stimulated. TMS is clinically used to quantify central motor conduction time in particular in patients with multiple sclerosis. Reliable information on amplitude changes e.g. in cervical myelopathy can be obtained by the triple stimulation technique.

Reflective fiber-optic magnetic field sensor based on a magnetic-fluid-filled capillary probe structure

A novel reflective magnetic field sensor is presented and experimentally demonstrated. The sensing probe is fabricated by splicing a section of uncoated four-core fiber (FCF) between two sections of no-core fibers (NCFs), and the end face of the last NCF is coated by silver. The sensor structure is sealed in a magnetic fluid (MF)-filled capillary, so that the NCF–FCF–NCF magnetic field sensing probe structure is obtained. The NCF is used to excite the high-order modes of the FCF’s cladding. Combined with the adjustable refractive index of MF, the sensor is sensitive to the magnetic field and temperature. Experimental results indicate that the presented sensor can measure the low magnetic field and high magnetic field. In the low magnetic field ranges of 0–10 mT and 10–18 mT, the wavelength near 1548 nm varies linearly with the magnetic field intensity, and the sensitivities are −7.43 pm mT−1 and −60 pm mT−1, respectively. The sensitivity of the interference intensity is −0.30782 dB mT−1 in the low magnetic field intensity range of 0–18 mT. The sensor under low magnetic field is also affected by temperature. In the temperature range of 20 °C–70 °C, the temperature sensitivity of the wavelength shift around 1548 nm is 62.33 pm °C−1, and the corresponding sensitivities of the interference intensity are −0.03888 dB °C−1 and −0.02076 dB °C−1 in the range of 30 °C–50 °C and 50 °C–70 °C, respectively. However, the effect of temperature on the sensor in the high magnetic field (18–36 mT) can be ignored. Within the high magnetic field intensity range of 26–36 mT, the sensitivity of the interference intensity near 1598 nm is −1.20993 dB mT−1. The dual-parameter matrix is used to eliminate the cross-sensitivity of temperature in the low magnetic field. This sensor, with the advantages of easy fabrication, high sensitivity and low cost, has the potential application in the magnetic field monitoring.

Measuring viscoelastic parameters in Magnetic Resonance Elastography: a comparison at high and low magnetic field intensity

Magnetic Resonance Elastography (MRE) is a non-invasive imaging technique which involves motion-encoding MRI for the estimation of the shear viscoelastic properties of soft tissues through the study of shear wave propagation. The technique has been found informative for disease diagnosis, as well as for monitoring of the effects of therapies. The development of MRE and its validation have been supported by the use of tissue-mimicking phantoms. In this paper we present our new MRE protocol using a low magnetic field tabletop MRI device at 0.5 T and sinusoidal uniaxial excitation in a geometrical focusing condition. Results obtained for gelatin are compared to those previously obtained using high magnetic field MRE at 11.7 T. A multi-frequency investigation is also provided via a comparison of commonly used rheological models: Maxwell, Springpot, Voigt, Zener, Jeffrey, fractional Voigt and fractional Zener. Complex shear modulus values were comparable when processed from images acquired with the tabletop low field scanner and the high field scanner. This study serves as a validation of the presented tabletop MRE protocol and paves the way for MRE experiments on ex-vivo tissue samples in both normal and pathological conditions.

2-D–3-D Combined Numerical Method for Optimal Design of Magnetic Field Generator in Analytical Ferrograph

Analytical ferrograph (AF) is mainly used for the wear debris analysis in the lubrication oil of mechanical equipment, and the high-intensity magnetic field establishment of magnetic field generator (MFG) in AF is one of the key problems in design of AF. This article proposes an analytical, numerical, and experimental methodology for magnetic field design of AF. Based on Ohm's law and Gauss's flux law, the magnetic flux leakage coefficient of MFG is obtained, and then, the theoretical value of magnetic induction intensity at the working air gap is calculated, which provides a basis for the numerical method. Then, a 2-D finite-element model (FEM) is established to determine the magnetic circuit parameters of MFG, and a 3-D FEM is further developed to determine the ferrogram position parameters. Through the numerical calculations, the influence laws of magnetic circuit parameters and ferrogram position parameters on the magnetic field of MFG are obtained, and the optimal parameter ranges are determined. A Gauss meter is used for the magnetic field measurement, and the error between the experimental and numerical results is obtained to verify the correctness of the proposed numerical method. The average error between the measured and numerically calculated values is 6.07%. This article provides a positive contribution for wear particle analysis and the quick and accurate ferrogram preparation by AF.

Analysis and design of the induction coil for a 2.1 m / 120 mT magnetic field qualification test facility

Equipment mounted around tokamak devices are usually exposed to high intensity magnetic field and suffers from severe interference problems. To qualify the operation reliability of sensitive devices under strong magnetic field environment, a magnetic field qualification test facility was designed and built in Chinese Academy of Sciences, Institute of Plasma Physics (ASIPP). This paper presents the analysis and design of the induction coil for this test facility. At first, a field homogeneity analysis is performed and an optimized three-coil configuration with minimum power loss and conductor mass is obtained. Then, the electrical, structural and cooling designs are conducted and verified by finite element analysis. At last, error field analysis is performed to evaluate the influence of installation misalignment. The designed induction coil is capable of generating a homogeneous magnetic field with a field inhomogeneity of 1.2 in a 2.1 m side-length cubic zone. The test facility enables the qualification test for the devices with a maximum dimension within 2.1 m and at a highest nominal test level of 120 m T. Further, the optimization design method can be extended to the design of some other fusion auxiliary devices.

DL-MRI: A Unified Framework of Deep Learning-Based MRI Super Resolution.

Magnetic resonance imaging (MRI) is widely used in the detection and diagnosis of diseases. High-resolution MR images will help doctors to locate lesions and diagnose diseases. However, the acquisition of high-resolution MR images requires high magnetic field intensity and long scanning time, which will bring discomfort to patients and easily introduce motion artifacts, resulting in image quality degradation. Therefore, the resolution of hardware imaging has reached its limit. Based on this situation, a unified framework based on deep learning super resolution is proposed to transfer state-of-the-art deep learning methods of natural images to MRI super resolution. Compared with the traditional image super-resolution method, the deep learning super-resolution method has stronger feature extraction and characterization ability, can learn prior knowledge from a large number of sample data, and has a more stable and excellent image reconstruction effect. We propose a unified framework of deep learning -based MRI super resolution, which has five current deep learning methods with the best super-resolution effect. In addition, a high-low resolution MR image dataset with the scales of ×2, ×3, and ×4 was constructed, covering 4 parts of the skull, knee, breast, and head and neck. Experimental results show that the proposed unified framework of deep learning super resolution has a better reconstruction effect on the data than traditional methods and provides a standard dataset and experimental benchmark for the application of deep learning super resolution in MR images.

Changes in the Structure of the Benzylpenicillin Sodium Salt Molecule under the Pulsed Magnetic Field

The study aims at the Fourier spectra of an antibiotic exposed to a high-intensity pulsed magnetic field. The applied frequency was f = 40 kHz, with a number of pulses n = 1, at intensities of the pulsed magnetic field H = 0.09 × 106 А/m, Н = 0.50 × 106 А/m, Н = 0.82 × 106 А/m. It was assumed that under the conditions of the pulsed magnetic field there might be a change in the structure of the drug molecule. The research has revealed that an increase in the pulsed magnetic field power leads first to a decrease in the intensity of the band in the Fourier spectrum, and then to its increase. In addition, changes were recorded in the amide group of benzylpenicillin sodium salt molecules depending on the intensity of the pulsed magnetic field applied to the antibiotic.

Чисельні та експериментальні дослідження з визначення ефективності роботи поліградієнтного електромагнітного сепаратора удосконаленої конструкції

У статті для оцінювання переваг удосконаленої конструкції пліградієнтного електромагнітного сепаратора перед базовою проведені дослідження розподілу магнітної індукції в робочій зоні пластинчастої матриці сепаратора. Для вирішення цього завдання був задіяний метод скінченних елементів, реалізований у тривимірній постановці в модулі Magnet програмного комплексу Infolytica. В удосконаленій конструкції електромагнітного сепаратора суміжні ряди паралельних феромагнітних пластин матриці встановлено із послідовним чергуванням трикутних виступів та впадин у протилежних напрямках.Встановлено, що це забезпечить найбільш рівномірний розподіл локальних зон з високою інтенсивністю та неоднорідність магнітного поля в робочому об’ємі матриці сепаратора у порівнянні з базовою конструкцією та створить умови для збільшення ефективності видалення дрібнодисперсних феромагнітних та слабомагнітних домішок крупністю менше 1 мм. Виконане порівняння результатів експериментальних досліджень розподілу магнітної індукції для базової конструкції з результатами чисельних розрахунків для удосконаленої конструкції електромагнітного сепаратора. Для визначення ефективності роботи поліградієнотного електромагнітного сепаратора удосконаленої конструкції були проведені експериментальні дослідження на фізичній моделі з використанням проби борошна з різною вихідною концентрацією металевих домішок розміром від 0,01 до 5 мм.Вилучений метал зважували на аналітичних вагах та визначали його концентрацію. Експеримент проводився в умовах сталого температурного режиму. За результатами експерименту було встановлено, що при невисокій концентрації металевих домішок у пробі борошна (менше 1 г на 1 кг продукту) більш високу ефективність вилучення металевих включень забезпечує удосконалена конструкція поліградієнтного електромагнітного сепаратора.

Fiber Vector Magnetometer Based on Balloon-Like Fiber Structure and Magnetic Fluid

A compact vector magnetometer based on balloon-like fiber structure functionalized by magnetic fluid (MF) was proposed. To fabricate the sensor, the single mode fiber (SMF) was bent into a balloon-like structure, and then the shape was fixed by using the alcohol lamp flame. Because of the bending, the fiber core mode leaks into the cladding, thereby forming higher order cladding modes that are sensitive to the variations of external refractive index. When the structure is encapsulated in MF, due to the anisotropic distribution of ferromagnetic nanoparticles under magnetic field, the refractive index around the fiber structure also presents anisotropy. By measuring the refractive index of the MF under different magnetic-field directions and intensities, both the measurement of the magnetic field intensity and direction can be achieved. The experimental results show that a high magnetic field intensity sensitivity of 0.78 nm/mT and a high magnetic-field direction sensitivity of 0.094°/mT were obtained. Due to the simple fabricating method, low cost, and highly sensitivity, the proposed fiber vector magnetometer has potential applications in the navigation, aviation, and electric power industry.

Time Domain Analysis of the Effect of Apertures on the Shielding Effectiveness of Buildings

High intensity electric and magnetic fields produced by lightning discharge can penetrate through any structure in its vicinity. Installation of a sensitive component inside any structure complying the Electromagnetic Compatibility standards need the information of exposure limit of the equipment in the installation environment. Any structure provides natural shielding to electromagnetic field and its limit depends on the material properties. In addition the structure dimension plays key role in defining the limit of shielding. This paper investigates the effect of aperture on the shielding effectiveness of building structure made of construction material against lightning electromagnetic fields. Building structures constructed in computer aided design (CAD) tool, are subjected to lighting electromagnetic field in FEKO Electromagnetic simulation software. Time domain approach is used to compute the shielding effectives of the building for different structural variations. It is seen that apertures decrease the shielding effectiveness of the building . As the structure size increases the percentage decrease in shielding effectiveness due to the presence of aperture increases. For magnetic field, construction material does not provide considerable shielding.

PURIFICATION OF FELDSPAR FROM IRON OXIDE IMPURITIES USING NITRIC ACID IN PRESENCE OF AMMONIUM BIUORIDE

The main objective of this study is focused on the mechanical preparation of Algerian crude feldspar with a view to extract the information about the comminution and the coloring iron rate distribution, on the one hand, and to remove the iron oxides, on the other hand, main impurities of crude feldspar by magnetic separation, flotation and more particularly by chemical leaching. In this process, the nitric acid and dithionite as reducing agent are used to replace sulfuric acid whose the application tests have yielded negative results. Research results shows that using a nitric acid in a reducing medium as ammonium bifluoride (HF,NH4F) process is effective and pushes the degree of iron oxides (Fe2O3) removal around 0.01\%. The hydro-metallurgical process applied especially to size fractions [-0.8 + 0.1] mm intended for the glass industry previously undergo a high intensity magnetic field reduces iron levels up to 0.054 \% with a yields in terms of weight of 58.32\% compared to those of all comers.

Hall and induced magnetic field effects on convective flow of viscoelastic fluid within an inclined channel with periodic surface conditions

This paper is concerned with the analytical study of the convective flow of a viscoelastic electrically conducting fluid within an inclined channel bounding a porous regime with Hall and induced magnetic field effects. An external magnetic field of high intensity is applied in the direction normal to the inclined surface. The left inclined surface of the channel is considered to be non-magnetic while the right inclined surface is assumed to be magnetized. Suitable non-dimensional transformations are used to reduce the problem to a similar non-dimensional problem. The resulting flow governing equations are solved analytically. The consequences of various flow influencing parameters to the flow variables are numerically computed and presented in graphical and tabular form. It is interesting to note that the growth in angle of inclination reduces the induced magnetic field in the left half of the channel while this effect is opposite in the vicinity of the right inclined surface due to magnetization of this surface.

Measurement of the magnetic properties of thin films based on the spin Hall effect of light.

Using the spin Hall effect of light, this work proposes a measurement technique of the magnetic properties of thin films. The beam shift of the spin Hall effect of light is used to replace the magneto-optical Kerr rotation angle as a parameter to characterize the magnetism of thin films. The technique can easily achieve an accuracy of 10-6 rad of the magneto-optical Kerr rotation angle which can, in theory, be further improved to 10-8 rad. We also proposed two methods to solve the problem of the exceeding linear response region of the measurement under high magnetic field intensity, making it more conducive to practical application. This technique has great potential for application in the magnetic measurement of ultra-thin films with particular emphasis on thicknesses within several atomic layers.

The response of the neuronal activity in the somatosensory cortex after high-intensity intermediate-frequency magnetic field exposure to the spinal cord in rats under anesthesia and waking states

Novel technologies using the intermediate-frequency magnetic field (IF-MF) in living environments are becoming popular with the advance in electricity utilization. However, the biological effects induced by the high-intensity and burst-type IF-MF exposure used in the wireless power transfer technologies for electric vehicles or medical devices, such as the magnetic stimulation techniques, are not well understood. Here, we developed an experimental platform using rats, that combined an 18 kHz, high-intensity (Max. 88 mT), Gaussian-shaped burst IF-MF exposure system with an in vivo extracellular recording system. In this paper, we aimed to report the qualitative differences in stimulus responses in the regions of the somatosensory cortex and peripheral nerve fibers that were induced by the IF-MF exposure to the rat spinal cord. We also report the modulation of the stimulus responses in the somatosensory cortex under anesthesia or waking states. Using this experimental platform, we succeeded in the detection of the motor evoked potentials or the neuronal activity in the somatosensory cortex that was induced by the IF-MF exposure to the spinal cord in rats. Compared to the state of anesthesia, the neuronal activities in the somatosensory cortex was enhanced during the waking state. On the other hand, these neuronal responses could not be confirmed by the IF-MF exposure-related coil sound only. Our experimental results indicated the basic knowledge of the biological responses and excitation mechanisms of the spinal cord stimulation by the IF-MF exposure.

ESTIMATION OF THERMAL POWER PLANT WORKERS EXPOSURE TO MAGNETIC FIELDS AND SIMULATION OF HAZARD ZONES.

Extremely low-frequency magnetic fields (ELF-MFs) have raised some concerns due to their possible effects on workers' health. In this study ELF-MFs were measured in different units of the thermal power plant based on gridding the indoor space. The exposure level was measured by spot measurement based on the IEEE Std C95.3.1 and then simulated in units with the highest magnetic field intensity by using ArcGIS software. The operators and balance of plant (BOP) technicians (12.64±9.74μT) and office workers (2.41±1.22μT) had the highest and lowest levels of both measured and estimated ELF-MFs exposure. The highest measured ELF-MFs were in the vicinity of the power transmission lines in the transformers' building (48.2 μT). Our simulation showed the high and low exposure areas and ranked exposure well; but, the actual measurements of ELF-MFs exposure were in all cases higher than the estimated values, which means we still need to improve our estimations.

Feature of Entropy Generation in Cu-Al2O3/Ethylene Glycol Hybrid Nanofluid Flow Through a Rotating Channel

This paper aims to delineate the heat transfer enhancement and entropy generation of a magnetohydrodynamic (MHD) flow of a viscous incompressible electrically conducting non-Newtonian Casson hybrid nanofluid between two infinite parallel non-conducting plates channel in a rotating frame. Copper and aluminium oxide nanoparticles are dispersed in ethylene glycol (EG) as a base fluid. Casson model is deployed here to describe the constitutive behaviour of non-Newtonian fluids. The thermal radiation, viscous dissipation and Joule heating (Ohmic dissipation) effects are included in this model. Closed-form solutions are obtained for constitutive equations. Graphs and tables are presented and illustrated to disclose the impact of significant flow parameters on the flow system. The shear stresses and the rate of heat transfer are discussed numerically, and their numerical values for pertinent physical parameters are tabulated. The total entropy generation rate and Bejan number are also discussed and their interpretations with the physical parameters are conferred via graphs. The results obtained from the parametric analysis manifest that the temperature field is boosted up due to the high intensity of magnetic field as well as Coriolis force. The intensification of magnetic parameter contributes to an increase in the rate of heat transfer at the channel walls. The entropy generation can be minimized by improving Casson parameter. Moreover, a comparison between the flows of Casson hybrid nanofluid (Cu-Al2O3/EG) and Casson nanofluid (Cu-EG) is reported. Minimization in entropy generation is achieved for Casson hybrid nanofluid in comparison with Casson nanofluid.