Search results for: asymmetrical magnetic heads

Authors: N. Yogal, C. Lehrmann

Abstract:

The use of Permanent magnet (PM) is increasing in the Permanent magnet synchronous machines (PMSM) to fulfill the requirement of high efficiency machines in modern industry. PMSM is widely used in industrial application, wind power plant and automotive industry. Since the PMSM are used in different environment condition, the long-term effect of NdFeB-based magnets at high temperatures and corrosion behavior has to be studied due to irreversible loss of magnetic properties. In this paper, the effect of magnetic properties due to corrosion and increasing temperature in the climatic chamber has been presented. The magnetic moment and magnetic field of the magnet were studied experimentally.

Keywords: permanent magnet (PM), NdFeB, corrosion behavior, temperature effect, Permanent magnet synchronous machine (PMSM)

Procedia PDF Downloads 356

Authors: Chandni Rani, S. D. Tiwari

Abstract:

Ferrihydrite is one of the distinct minerals in the family of oxides, hydroxides and oxyhydroxides of iron. It is a nanocrystalline material. It occurs naturally in different sediments, soil systems and also found in the core of ferritin, an iron storage protien. This material can also be synthesized by suitable chemical methods in laboratories. This is known as less crystalline Iron (III) Oxyhydroxide. Due to its poor crystallinity, there are very broad peaks in x-ray diffraction. Depending on the number of peaks in x-ray diffraction pattern, it is classified as two lines and six lines ferrihydrite. The average crystallite size for these two forms is found to be about 2nm to 5nm. The exact crystal structure of this system is still under debate. Out of these two forms, the six lines ferrihydrite is more ordered in comparison to two lines ferrihydrite. The magnetic behavior of two lines ferrihydrite nanoparticles is somewhat well studied. But the magnetic behavior of six lines ferrihydrite nanoparticles could not attract the attention of researchers much. This motivated us to work on the magnetic properties of six lines ferrihydrite nanoparticles. In this work, we present synthesis, structural characterization and magnetic behavior of 5 nm six lines ferrihydrite nanoparticles. X-ray diffraction and transmission electron microscope are used for structural characterization of this system. Magnetization measurements are performed to fit the data at different temperatures. Then the effect of magnetic moment distribution is also found. All these observations are discussed in detail.

Keywords: nanoparticles, magnetism, superparamagnetism, magnetic anisotropy

Procedia PDF Downloads 311

Authors: Javier Sánchez, Laura Elena De León Prado, Dora Alicia Cortés Hernández

Abstract:

Magnetic spinel ferrites are materials that possess size, magnetic properties and heating ability adequate for their potential use in biomedical applications. The Mn_0.5Ga_0.5Fe₂O₄ magnetic nanoparticles (MNPs) were synthesized by sol-gel method using citric acid as chelating agent of metallic precursors. The synthesized samples were identified by X-Ray Diffraction (XRD) as an inverse spinel structure with no secondary phases. Saturation magnetization (Ms) of crystalline powders was 45.9 emu/g, which was higher than those corresponding to GaFe₂O₄ (14.2 emu/g) and MnFe₂O₄ (40.2 emu/g) synthesized under similar conditions, while the coercivity field (Hc) was 27.9 Oe. The average particle size was 18 ± 7 nm. The heating ability of the MNPs was enough to increase the surrounding temperature up to 43.5 °C in 7 min when a quantity of 4.5 mg of MNPs per mL of liquid medium was tested. Cytotoxic effect (hemolysis assay) of MNPs was determined and the results showed hemolytic values below 1% in all tested cases. According to the results obtained, these synthesized nanoparticles can be potentially used as thermoseeds for hyperthermia therapy.

Keywords: manganese-gallium ferrite, magnetic hyperthermia, heating ability, cytotoxicity

Procedia PDF Downloads 363

Authors: Andrea Leon, J. M. Florez, P. Vargas

Abstract:

The effect of hydrogen adsorption on the magnetic properties of fcc Ni has been calculated using the linear-muffin-tin-orbital formalism and using the local-density approximation for the exchange y correlation. The calculations for the ground state show that the sequential addition of hydrogen atoms is found to monotonically reduce the total magnetic moment of the Ni fcc structure, as a result of changes in the exchange-splitting parameter and in the Fermi energy. In order to physically explain the effect of magnetization reduction as the Hydrogen concentration increases, we propose a Stoner impurity model to describe the influence of H impurity on the magnetic properties of Nickel.

Keywords: electronic structure, magnetic properties, Nickel hydride, stoner model

Procedia PDF Downloads 429

Authors: Ismail Al-Yahmadi, Abbasher Gismelseed, Fatma Al-Mammari, Ahmed Al-Rawas, Ali Yousif, Imaddin Al-Omari, Hisham Widatallah, Mohamed Elzain

Abstract:

The influence of Fe-doping on the structural, magnetic and magnetocaloric properties of Nd₀.₆Sr₀.₄FeₓMn₁₋ₓO₃ (0≤ x ≤0.5) were investigated. The samples were synthesized by auto-combustion Sol-Gel method. The phase purity, crystallinity, and the structural properties for all prepared samples were examined by X-ray diffraction. XRD refinement indicates that the samples are crystallized in the orthorhombic single-phase with Pnma space group. Temperature dependence of magnetization measurements under a magnetic applied field of 0.02 T reveals that the samples with (x=0.0, 0.1, 0.2 and 0.3) exhibit a paramagnetic (PM) to ferromagnetic (FM) transition with decreasing temperature. The Curie temperature decreased with increasing Fe content from 256 K for x =0.0 to 80 K for x =0.3 due to increasing of antiferromagnetic superexchange (SE) interaction coupling. Moreover, the magnetization as a function of applied magnetic field (M-H) curves was measured at 2 K, and 300 K. the results of such measurements confirm the temperature dependence of magnetization measurements. The magnetic entropy change|∆SM | was evaluated using Maxwell's relation. The maximum values of the magnetic entropy change |-∆SMax |for x=0.0, 0.1, 0.2, 0.3 are found to be 15.35, 5.13, 3.36, 1.08 J/kg.K for an applied magnetic field of 9 T. Our result on magnetocaloric properties suggests that the parent sample Nd₀.₆Sr₀.₄MnO₃ could be a good refrigerant for low-temperature magnetic refrigeration.

Keywords: manganite perovskite, magnetocaloric effect, X-ray diffraction, relative cooling power

Procedia PDF Downloads 120

Authors: M. Kessi

Abstract:

We investigated the effect of the magnetic field on carrier transport phenomena in the transistor channel region of Double-Gate Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). This explores the Lorentz force and basic physical properties of solids exposed to a constant external magnetic field. The magnetic field modulates the electrons and potential distribution in the case of silicon Tunnel FETs. This modulation shows up in the device's external electrical characteristics such as ON current (ION), subthreshold leakage current (IOF), the threshold voltage (VTH), the magneto-transconductance (gm) and the output magneto-conductance (gDS) of Tunnel FET. Moreover, the channel doping concentration and potential distribution are obtained using the numerical method by solving Poisson’s transport equation in 3D modules semiconductor magnetic sensors available in Silvaco TCAD tools. The numerical simulations of the magnetic nano-sensors are relatively new. In this work, we present the results of numerical simulations based on 3D magnetic sensors. The results show excellent accuracy comportment and good agreement compared with that obtained in the experimental study of MOSFETs technology.

Keywords: single-gate MOSFET, magnetic field, hall field, Lorentz force

Procedia PDF Downloads 150

Authors: Charles Anthony S. Santillan, Jude Noel P. Jarina, Patricia Mae A. Cuevas, Julito B. Añora Jr.

Abstract:

The research examines the effectiveness of Two-Position and Tuned PID controllers in magnetic levitation systems. Magnetic levitation, a crucial technology in diverse industries, depends on meticulous control mechanisms for stability and performance. The study seeks to compare these two control strategies to ascertain their efficacy in practical applications. The paper explores the theoretical foundations of the controllers, presents an experimental methodology emphasizing setup and installation, and examines the results about stability, response time, and susceptibility to disturbances. By interpreting and discussing the findings, the research provides valuable perspectives on the practical ramifications of utilizing Two-Position and Tuned PID controllers in magnetic levitation systems. The conclusion encapsulates significant outcomes and proposes avenues for future research, thereby contributing to the progress of control strategies in magnetic levitation technology.

Keywords: arduino, comparative analysis, magnetic levitation, tuned PID controller, two-position controller

Procedia PDF Downloads 29

Authors: Muhammad Waqar Ashraf

Abstract:

The influence of magnetic field on the structure of water and aqueous solutions are similar and can alter the physical and chemical properties of water-dispersed systems. With the application of magnetic field, hydration of salt ions and other impurities slides down and improve the possible technological characteristics of the water. Magnetic field can enhance the characteristic of water i.e. better salt solubility, kinetic changes in salt crystallization, accelerated coagulation, etc. Gulf countries are facing critical problem due to depletion of water resources and increasing food demands to cover the human needs; therefore water shortage is being increasingly accepted as a major limitation for increased agricultural production and food security. In arid and semi-arid regions sustainable agricultural development is influenced to a great extent by water quality that might be used economically and effectively in developing agriculture programs. In the present study, the possibility of using magnetized water to desalinate the soil is accounted for the enhanced dissolving capacity of the magnetized water. Magnetic field has been applied to treat brackish water. The study showed that the impact of magnetic field on saline water is sustained up to three hours (with and without shaking). These results suggest that even low magnetic field can decrease the electrical conductivity and total dissolved solids which are good for the removal of salinity from the irrigated land by using magnetized water.

Keywords: magnetic treatment, saline water, hardness of water, removal of salinity

Procedia PDF Downloads 459

Authors: Raziyeh Mohammadi

Abstract:

At present, nanoparticles are used for various biomedical applications where they facilitate laboratory diagnostics and therapeutics. The performance of nanoparticles for biomedical applications is often assessed by their narrow size distribution, suitable magnetic saturation, and low toxicity effects. Superparamagnetic iron oxide nanoparticles have received great attention due to their applications as contrast agents for magnetic resonance imaging (MRI. (Processes in the tissue where the blood brain barrier is intact in this way shielded from the contact to this conventional contrast agent and will only reveal changes in the tissue if it involves an alteration in the vasculature. This technique is very useful for detecting tumors and can even be used for detecting metabolic functional alterations in the brain, such as epileptic activity.SPIONs have found application in Magnetic Resonance Imaging (MRI) and magnetic hyperthermia. Unlike bulk iron, SPIONs do not have remnant magnetization in the absence of the external magnetic field; therefore, a precise remote control over their action is possible.

Keywords: nanoparticles, MRI, biomedical, iron oxide, spions

Procedia PDF Downloads 183

Authors: B. Bouadjemi, S. Bentata, W. Benstaali, A. Abbad, T. Lantri, A. Zitouni

Abstract:

The purpose of this study was to investigate the structural,electronic and magnetic properties of the cubic praseodymium oxides perovskites PrMnO3. It includes our calculations based on the use of the density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA+U approaches, The spin polarized electronic band structures and densities of states as well as the integer value of the magnetic moment of the unit cell (6 μB) illustrate that PrMnO3 is half-metallic ferromagnetic. The study prove that the compound is half-metallic ferromagnetic however the results obtained, make the cubic PrMnO3 a promising candidate for application in spintronics.

Keywords: cubic, DFT, electronic properties, magnetic moment, spintronics

Procedia PDF Downloads 439

Authors: Yung-Jin Weng, Chia-Chi Chang, Chun-Yu Tsai

Abstract:

This paper is focused on the research of imprinting and replica molding of quasi-grey scale soft mold curved surface microstructure mold. In this paper, a magnetic photocuring forming system is first developed and built independently, then the magnetic curved surface microstructure soft mode is created; moreover, the magnetic performance of the magnetic curved surface at different heights is tested and recorded, and through experimentation and simulation, the magnetic curved surface microstructure soft mold is used in the research of quasi-grey scale soft mold curved surface microstructure imprinting and replica molding. The experimental results show that, under different surface curvatures and voltage control conditions, different quasi-grey scale array microstructures take shape. In addition, this paper conducts research on the imprinting and replica molding of photoresist composite magnetic powder in order to discuss the forming performance of magnetic photoresist, and finally, the experimental result is compared with the simulation to obtain more accurate prediction and results. This research is predicted to provide microstructure component preparation technology with heterogeneity and controllability, and is a kind of valid shaping quasi-grey scale microstructure manufacturing technology method.

Keywords: soft mold, magnetic, microstructure, curved surface

Procedia PDF Downloads 298

Authors: Mohamed Adel Abdallah

Abstract:

A high voltage magnetic pulse is designed by applying an electrical pulse to the coil. Capacitor banks are developed to generate a pulse current. Switching circuit consisting of DPDT switches, thyristor, and triggering circuit is built and tested. The coil current is measured using a Hall-effect current sensor. The magnetic pulse created is measured and tabulated in the graph. Simulation using FEMM is done to compare the results obtained between experiment and simulation. This technology can be applied to area such as medical equipment, measuring instrument, and military equipment.

Keywords: high voltage, magnetic pulse, capacitor discharge, coil

Procedia PDF Downloads 647

Authors: B. Bouadjemi, S. Bentata, W. Benstaali, A. Abbad, T. Lantri, A. Zitouni

Abstract:

The purpose of this study was to investigate the structural,electronic and magnetic properties of the cubic praseodymium oxides perovskites PrMnO3. It includes our calculations based on the use of the density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA+U approaches, The spin polarized electronic band structures and densities of states aswellas the integer value of the magnetic moment of the unit cell (6 μB) illustrate that PrMnO3 is half-metallic ferromagnetic. The study shows that the robust half-metallicity makes the cubic PrMnO3 a promising candidate for application in spintronics.

Keywords: Perovskite, DFT, electronic properties, Magnetic moment, half-metallic

Procedia PDF Downloads 424

Authors: Pierce Radecki, Pulkit Malik, Bharath Ramaswamy, Ben Shapiro

Abstract:

The ability to effectively design and test magnetic nanoparticles for controlled movement has been an elusive goal in the design of these particles. Magnetic nanoparticles of various characteristics have been created for use towards therapeutic effects, however the challenge of designing for controlled movement remains unmet. A step towards design in this aspect is a first principles model that captures and predicts the behaviors of particles in a magnetic field. The model is governed by four forces acting on the particles, the magnetic gradient, the dipole-dipole forces, the steric forces, and the viscous drag force. The particles are multi-core or single core, and incorporate a preferred magnetization axis. Particles exhibit behaviors, such as chaining, in simulations that are similar to those witnessed through experimentation. Currently, experimental results are being compared to the modeling results for verification of the model, through the analysis of chaining behaviors. This modeling system will be used in designing magnetic nanoparticles for specific chaining and movement behaviors.

Keywords: controlled movement, modeling, magnetic nanoparticles, nanoparticle design

Procedia PDF Downloads 281

Authors: O. Arbouche, Y. Benallou, K. Amara

Abstract:

We report a first-principles study of structural, electronic and magnetic properties of ternary plumbides (rare earth-transition metal-Plumb) Dy2Ni2Pb crystallizes with the orthorhombic structure of the Mn2AlB2 type (space group Cmmm), were studied by means of the full-relativistic version of the full-potential augmented plane wave plus local orbital method within the frame work of spin-polarized density functional theory (SP-DFT). The electronic exchange-correlation energy is described by generalized gradient approximation (GGA). We have calculated the lattice parameters, bulk modulii and the first pressure derivatives of the bulk modulii, total densities of states and magnetic properties. The calculated total magnetic moment is found to be equal to 9.52 μB.

Keywords: spin-polarized, magnetic properties, Dy2Ni2Pb, Density functional theory

Procedia PDF Downloads 269

Authors: Deva Kanta Phukan

Abstract:

An attempt is made where an electrically conducting fluid is injected from a fixed outer cylindrical casing onto an inner moving cylindrical rod. A magnetic field is applied parallel to the axis of the cylindrical rod. The basic governing set of partial differential equations for conservation of mass and momentum are reduced to a set of non-linear ordinary differential equation by introducing similarity transformation, which are integrated numerically. A perturbation solution for the case of large magnetic parameter is derived for constant Reynolds number.

Keywords: annular axi-symmetric stagnation flow, conducting fluid, magnetic field, moving cylinder

Procedia PDF Downloads 373

Authors: Risdiana, D. Suhendar, S. Pratiwi, W. A. Somantri, T. Saragi

Abstract:

Superconductor is a promising material for future applications especially for energy saving because of their advantages properties such as zero electrical resistivity when they are cooled down to sufficiently low temperatures. However, the mechanism describing the role of physical properties in superconductor is far from being understood clearly, so that the application of this material for wider benefit in various industries is very limited. Most of superconductors are cuprate compounds, which has CuO2 as a conducting plane in their crystal structures. The study of physical properties through the partially substitution of impurity for Cu in superconducting cuprates has been one of great interests in relation to the mechanism of superconductivity. Different behaviors between the substitution of nonmagnetic impurity and magnetic impurity for Cu are observed. For examples, the superconductivity and Cu-spin fluctuations in the electron-doped system are suppressed through the substitution of magnetic Ni for Cu more markedly than through the substitution of nonmagnetic Zn for Cu, which is contrary to the result in the hole-doped system. Here, we reported the effect of partially substitution of magnetic impurity Fe for Cu to the magnetic and transport properties in electron-doped superconducting cuprates of Eu1.85+yCe0.15-yCu1-yFeyO4+α-δ (ECCFO) with y = 0.01, 0.02, and 0.05, in order to investigate the mechanism of magnetic and transport properties of ECCFO in normal-state. Magnetic properties are investigated by DC magnetic-susceptibility measurements that carried out at low temperatures down to 2 K using a standard SQUID magnetometer in a magnetic field of 5 Oe on field cooling. Transport properties addressed to electron mobility, are extracted from radius of electron localization calculated from temperature dependence of resistivity. For y = 0, temperature dependence of dc magnetic-susceptibility indicated the change of magnetic behavior from paramagnetic to diamagnetic below 15 K. Above 15 K, all samples show paramagnetic behavior with the values of magnetic moment in every volume unit increased with increasing y. Electron mobility decreased with increasing y. Some reasons for these results will be discussed.

Keywords: DC magnetic-susceptibility, electron mobility, Eu1.85+yCe0.15-yCu1-yFeyO4+α-δ, normal state

Procedia PDF Downloads 320

Authors: Po-Wen Chen, Jin-Yu Wu, Md. Manirul Ali, Yang Peng, Chen-Te Chang, Der-Jun Jan

Abstract:

Dynamics of cathode spot has become a major part of vacuum arc discharge with its high academic interest and wide application potential. In this article, using a three-dimensional statistical model, we simulate the distribution of the ignition probability of a new cathode spot occurring in different magnetic pressure on old cathode spot surface and at different arcing time. This model for the ignition probability of a new cathode spot was proposed in two typical situations, one by the pure isotropic random walk in the absence of an external magnetic field, other by the retrograde motion in external magnetic field, in parallel with the cathode surface. We mainly focus on developed relationship between the ignition probability density distribution of a new cathode spot and the external magnetic field.

Keywords: cathode spot, vacuum arc discharge, transverse magnetic field, random walk

Procedia PDF Downloads 407

Authors: Mst Nazmunnahar, Juan del Val, Alena Vimmrova, Blanca Hernando, Julian González

Abstract:

We report the microstructural and magnetic properties of Ni50Mn39Sn11 and Ni50Mn36Sn14 ribbon Heusler alloys. Experimental results were obtained by differential scanning calorymetry, X-ray diffraction and vibrating sample magnetometry techniques. The Ni-Mn-Sn system undergoes a martensitic structural transformation in a wide temperature range. For example, for Ni50Mn39Sn11 the start and finish temperatures of the martensitic and austenite phase transformation for ribbon alloy were Ms = 336K , Mf = 328K, As = 335K and Af = 343K whereas no structural transformation is observed for Ni50Mn36Sn14 alloys. Magnetic measurements show the typical ferromagnetic behavior with Curie temperature 207K at low applied field of 50 Oe. The complex behavior exhibited by these Heusler alloys should be ascribed to the strong coupling between magnetism and structure, being their magnetic behavior determined by the distance between Mn atoms.

Keywords: as-cast ribbon, Heusler alloys, magnetic properties, structural transformation

Procedia PDF Downloads 419

Authors: Jefunnie Matahum, Yu-Chi Kuo, Chao-Ming Su, Tzong-Rong Ger

Abstract:

Magnetic cell labeling is of great importance in various applications in biomedical fields such as cell separation and cell sorting. Since analytical methods for quantification of cell uptake of magnetic nanoparticles (MNPs) are already well established, image analysis on single cell level still needs more characterization. This study reports an alternative non-destructive quantification methods of single-cell uptake of positively charged MNPs. Magnetophoresis experiments were performed to calculate the number of MNPs in a single cell. Mobility of magnetic cells and the area of intracellular MNP stained by Prussian blue were quantified by image processing software. ICP-MS experiments were also performed to confirm the internalization of MNPs to cells. Initial results showed that the magnetic cells incubated at 100 µg and 50 µg MNPs/mL concentration move at 18.3 and 16.7 µm/sec, respectively. There is also an increasing trend in the number and area of intracellular MNP with increasing concentration. These results could be useful in assessing the nanoparticle uptake in a single cell level.

Keywords: magnetic nanoparticles, single cell, magnetophoresis, image analysis

Procedia PDF Downloads 305

Authors: Khimmatali Nomozovich Juraev

Abstract:

Silicon carbide is one of the promising materials with potential applications in electronic devices using high power, high frequency and high electric field. Currently, silicon carbide is used to manufacture high power and frequency diodes, transistors, radiation detectors, light emitting diodes (LEDs) and other functional devices. In this work, the effects of magnetic field on p-n junctions based on 4H-SiC were experimentally studied. As a research material, monocrystalline silicon carbide wafers (Cree Research, Inc., USA) with relatively few growth defects grown by physical vapor transport (PVT) method were used: Nd dislocations 104 cm², Nm micropipes ~ 10–10² cm-², thickness ~ 300-600 μm, surface ~ 0.25 cm², resistivity ~ 3.6–20 Ωcm, the concentration of background impurities Nd − Na ~ (0.5–1.0)×1017cm-³. The initial parameters of the samples were determined on a Hall Effect Measurement System HMS-7000 (Ecopia) measuring device. Diffusing Ni nickel atoms were covered to the silicon surface of silicon carbide in a Universal Vacuum Post device at a vacuum of 10-⁵ -10-⁶ Torr by thermal sputtering and kept at a temperature of 600-650°C for 30 minutes. Then Ni atoms were diffused into the silicon carbide 4H-SiC sample at a temperature of 1150-1300°C by low temperature diffusion method in an air atmosphere, and the effects of the magnetic field on the I-V characteristics of the samples were studied. I-V characteristics of silicon carbide 4H-SiC p-n junction sample were measured in the magnetic field and in the absence of a magnetic field. The measurements were carried out under conditions where the magnitude of the magnetic field induction vector was 0.5 T. In the state, the direction of the current flowing through the diode is perpendicular to the direction of the magnetic field. From the obtained results, it can be seen that the magnetic field significantly affects the I-V characteristics of the p-n junction in the magnetic field when it is measured in the forward direction. Under the influence of the magnetic field, the change of the magnetic resistance of the sample of silicon carbide 4H-SiC p-n junction was determined. It was found that changing the magnetic field poles increases the direct forward current of the p-n junction or decreases it when the field direction changes. These unique electrical properties of the 4H-SiC p-n junction sample of silicon carbide, that is, the change of the sample's electrical properties in a magnetic field, makes it possible to fabricate magnetic field sensing devices based on silicon carbide to use at harsh environments in future. So far, the productions of silicon carbide magnetic detectors are not available in the industry.

Keywords: 4H-SiC, diffusion Ni, effects of magnetic field, I-V characteristics

Procedia PDF Downloads 62

Authors: Farhad Aalizadeh, Ali Moosavi

Abstract:

This paper presents a two-dimensional Computational Fluid Dynamics (CFDs) simulation for the steady, particle tracking. The purpose of this paper is applied magnetic field effect on Magnetic Nanoparticles velocities distribution. It is shown that the permeability of the particles determines the effect of the magnetic field on the deposition of the particles and the deposition of the particles is inversely proportional to the Reynolds number. Using MHD and its property it is possible to control the flow velocity, remove the fouling on the walls and return the system to its original form. we consider a channel 2D geometry and solve for the resulting spatial distribution of particles. According to obtained results when only magnetic fields are applied perpendicular to the flow, local particles velocity is decreased due to the direct effect of the magnetic field return the system to its original fom. In the method first, in order to avoid mixing with blood, the ferromagnetic particles are covered with a gel-like chemical composition and are injected into the blood vessels. Then, a magnetic field source with a specified distance from the vessel is used and the particles are guided to the affected area. This paper presents a two-dimensional Computational Fluid Dynamics (CFDs) simulation for the steady, laminar flow of an incompressible magnetorheological (MR) fluid between two fixed parallel plates in the presence of a uniform magnetic field. The purpose of this study is to develop a numerical tool that is able to simulate MR fluids flow in valve mode and determineB0, applied magnetic field effect on flow velocities and pressure distributions.

Keywords: MHD, channel clots, magnetic nanoparticles, simulations

Procedia PDF Downloads 339

Authors: Niru Chowdhury, Subhankar Bedanta, Alexander Weber, Thomas Brueckel

Abstract:

We show the effect of interlayer coupling on magnetization reversal in purely dipolar coupled magnetic multilayers. Longitudinal magneto-optic Kerr microscopy (LMOKE) has been performed on [Co(10nm)/Al2O3(t)/Co(10nm)] for various thicknesses of Al2O3(t). We will show that inter-layer coupling interactions lead to layer-by-layer reversal in the magnetic multilayers. Also transverse component of magnetization was observed for higher thickness of the spacer layer.

Keywords: Interlayer coupling, Magnetic domains, Magneto – Optic Kerr effect microscopy, Magnetization reversal, Magnetic thin film

Procedia PDF Downloads 370

Authors: Shu-Jen Chen, Yi-Chien Wan, Ruey-Chi Wang

Abstract:

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) can be applied to the fabrication of bone replacement materials, the composite of dental filling, and the adsorption of biomolecules and dyes. The integration of HAp and magnetic materials would offer several advantages for bio-separation process because the magnetic adsorbents is capable of recovered by applied magnetic field. C-phycocyanin (C-PC) and Allophycocyanin (APC), isolated from Spirulina platensis, can be used in fluorescent labeling probes, health care foods and clinical diagnostic reagents. Although the purification of C-PC and APC are reported by HAp adsorption, the adsorption of C-PC and APC by magnetic HAp composites was not reported yet. Therefore, the fabrication of HAp with magnetic silica nanoparticles for proteins adsorption was investigated in this work. First, the magnetic silica particles were prepared by covering silica layer on Fe3O4 nanoparticles with a reverse micelle method. Then, the Fe3O4@SiO2 nanoparticles were mixed with calcium carbonate to obtain magnetic silica/calcium carbonate composites (Fe3O4@SiO2/CaCO3). The Fe3O4@SiO2/CaCO3 was further reacted with K2HPO4 for preparing the magnetic silica/hydroxyapatite composites (Fe3O4@SiO2/HAp). The adsorption experiments indicated that the adsorption capacity of Fe3O4@SiO2/HAp toward C-PC and APC were highest at pH 6. The adsorption of C-PC and APC by Fe3O4@SiO2/HAp could be correlated by the pseudo-second-order model, indicating chemical adsorption dominating the adsorption process. Furthermore, the adsorption data showed that the adsorption of Fe3O4@SiO2/HAp toward C-PC and APC followed the Langmuir isotherm. The isoelectric points of C-PC and APC were around 5.0. Additionally, the zeta potential data showed the Fe3O4@SiO2/HAp composite was negative charged at pH 6. Accordingly, the adsorption mechanism of Fe3O4@SiO2/HAp toward C-PC and APC should be governed by hydrogen bonding rather than electrostatic interaction. On the other hand, as compared to C-PC, the Fe3O4@SiO2/HAp shows higher adsorption affinity toward APC. Although the Fe3O4@SiO2/HAp cannot recover C-PC and APC from Spirulina platensis homogenate, the Fe3O4@SiO2/HAp can be applied to separate C-PC and APC.

Keywords: hydroxyapatite, magnetic, C-phycocyanin, allophycocyanin

Procedia PDF Downloads 122

Authors: Christopher Baiyegunhi, Oswald Gwavava

Abstract:

The location/source of the Beattie magnetic anomaly (BMA) and interconnectivity of geologic structures at depth have been a topic of investigation for over 30 years. Up to now, no relationship between geological structures (interconnectivity of dolerite intrusions) at depth has been established. Therefore, the environmental impact of fracking the Karoo for shale gas could not be assessed despite the fact that dolerite dykes are groundwater localizers in the Karoo. In this paper, we shed more light to the unanswered questions concerning the possible location of the source of the BMA, the connectivity of geologic structures like dolerite dykes and sills at depth and this relationship needs to be established before the tectonic evolution of the Karoo basin can be fully understood and related to fracking of the Karoo for shale gas. The result of the magnetic investigation and modelling of four gravity profiles that crosses the BMA in the study area reveals that the anomaly, which is part of the Beattie magnetic anomaly tends to divide into two anomalies and continue to trend in an NE-SW direction, the dominant gravity signatures is of long wavelength that is due to a deep source/interface inland and shallows towards the coast, the average depth to the top of the shallow and deep magnetic sources was estimated to be approximately 0.6 km and 15 km, respectively. The BMA become stronger with depth which could be an indication that the source(s) is deep possibly a buried body in the basement. The bean-shaped anomaly also behaves in a similar manner like the BMA thus it could possibly share the same source(s) with the BMA.

Keywords: Beattie magnetic anomaly, magnetic sources, modelling, Karoo Basin

Procedia PDF Downloads 523

Authors: Safoin Aktaou, Aya Al Masri, Kamel Guerchouche, Malorie Martin, Fouad Maaloul

Abstract:

Introduction: In the ‘Magnetic Resonance Imaging (MRI)’ department, all workers involved in preparing the patient, setting it up, tunnel cleaning, etc. are likely to be exposed to ‘ElectroMagnetic fields (EMF)’ emitted by the MRI device. Exposure to EMF can cause adverse radio-biological effects to workers. The purpose of this study is to propose an organizational process to manage and control EMF risks. Materials and methods: The study was conducted at seven MRI departments using machines with 1.5 and 3 Tesla magnetic fields. We assessed the exposure of each one by measuring the two electromagnetic fields (static and dynamic) at different distances from the MRI machine both inside and around the examination room. Measurement values were compared with British and American references (those of the UK's ‘Medicines and Healthcare Regulatory Agency (MHRA)’ and the ‘American Radiology Society (ACR)’). Results: Following the results of EMF measurements and their comparison with the recommendations of learned societies, a zoning system that adapts to needs of different MRI services across the country has been proposed. In effect, three risk areas have been identified within the MRI services. This has led to the development of a good practice guide related to the magnetic protection of MRI workers. Conclusion: The guide established by our study is a standard that allows MRI workers to protect themselves against the risk of electromagnetic fields.

Keywords: comparison with international references, measurement of electromagnetic fields, magnetic protection of workers, magnetic resonance imaging

Procedia PDF Downloads 125

Authors: Igor Pejic

Abstract:

The main focus of this research will be on analyzing correlative links between terrorism as an asymmetrical threat and the consequences it leaves on conventional security forces. The methodology behind the research will include qualitative research methods focusing on comparative analysis of books, scientific papers, documents and other sources, in order to deduce, explore and formulate the results of the research. With the coming of the 21^st century and the rising multi-polar, new world threats quickly emerged. The realistic approach in international relations deems that relations among nations are in a constant state of anarchy since there are no definitive rules and the distribution of power varies widely. International relations are further characterized by egoistic and self-orientated human nature, anarchy or absence of a higher government, security and lack of morality. The asymmetry of power is also reflected on countries' security capabilities and its abilities to project power. With the coming of the new millennia and the rising multi-polar world order, the asymmetry of power can be also added as an important trait of the global society which consequently brought new threats. Among various others, terrorism is probably the most well-known, well-based and well-spread asymmetric threat. In today's global political arena, terrorism is used by state and non-state actors to fulfill their political agendas. Terrorism is used as an all-inclusive tool for regime change, subversion or a revolution. Although the nature of terrorist groups is somewhat inconsistent, terrorism as a security and social phenomenon has a one constant which is reflected in its political dimension. The state's security apparatus, which was embodied in the form of conventional armed forces, is now becoming fragile, unable to tackle new threats and to a certain extent outdated. Conventional security forces were designed to defend or engage an exterior threat which is more or less symmetric and visible. On the other hand, terrorism as an asymmetrical threat is a part of hybrid, special or asymmetric warfare in which specialized units, institutions or facilities represent the primary pillars of security. In today's global society, terrorism is probably the most acute problem which can paralyze entire countries and their political systems. This problem, however, cannot be engaged on an open field of battle, but rather it requires a different approach in which conventional armed forces cannot be used traditionally and their role must be adjusted. The research will try to shed light on the phenomena of modern day terrorism and to prove its correlation with the state conventional armed forces. States are obliged to adjust their security apparatus to the new realism of global society and terrorism as an asymmetrical threat which is a side-product of the unbalanced world.

Keywords: asymmetrical warfare, conventional forces, security, terrorism

Procedia PDF Downloads 235

Authors: Sijo S. Thomas, S. Hridya, Manoj Mohan, Bibin Jacob, Hysen Thomas

Abstract:

Ferrites are iron based oxides with technologically significant magnetic properties and have widespread applications in medicine, technology, and industry. There has been a growing interest in the study of magnetic, electrical and structural properties of mixed ferrites. In the present work, structural and magnetic properties of Nickel and Calcium substituted Fe₃O₄ nanoparticles were investigated. NiₓCa₁₋ₓFe₂O₄ nanoparticles (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized by chemical co-precipitation method and the samples were subsequently sintered at 900°C. The magnetic and structural properties of NiₓCa₁₋ₓFe₂O₄ were investigated using Vibrating Sample Magnetometer and X-Ray diffraction. The XRD results revealed that the synthesized particles have nanometer size and it varies from 46-72 nm as the calcium concentration diminishes. The variation is explained based on the increase in the reaction rate with Ni concentration which favors the formation of ultrafine particles of mixed ferrites. VSM results show pure CaFe₂O₄ exhibit paramagnetic behavior with low saturation value. As the concentration of Ca decreases, a transition occurs from paramagnetic state to ferromagnetic state. When the concentration of Ni becomes dominant, magnetic saturation, coercivity, and retentivity become high, indicating near ferromagnetic behavior of the compound.

Keywords: co-precipitation, ferrites, magnetic behavior, structure

Procedia PDF Downloads 210

Authors: Fernández-Brito David, Lopez-Medina Javier Alonso, Murillo-Bracamontes Eduardo Antonio, Palomino-Ovando Martha Alicia, Gervacio-Arciniega José Juan

Abstract:

Magnetic Force Microscopy (MFM) is an Atomic Force Microscopy (AFM) technique that characterizes, at a nanometric scale, the magnetic properties of ferromagnetic materials. Conventional MFM works by scanning in two different AFM modes. The first one is tapping mode, in which the cantilever has short-range force interactions with the sample, with the purpose to obtain the topography. Then, the lift AFM mode starts, raising the cantilever to maintain a fixed distance between the tip and the surface of the sample, only interacting with the magnetic field forces of the sample, which are long-ranged. In recent years, there have been attempts to improve the MFM technique. Bimodal MFM was first theoretically developed and later experimentally proven. In bimodal MFM, the AFM internal piezoelectric is used to cause the cantilever oscillations in two resonance modes simultaneously, the first mode detects the topography, while the second is more sensitive to the magnetic forces between the tip and the sample. However, it has been proven that the cantilever vibrations induced by the internal AFM piezoelectric ceramic are not optimal, affecting the bimodal MFM characterizations. Moreover, the Secondary Resonance Magnetic Force Microscopy (SR-MFM) was developed. In this technique, a coil located below the sample generates an external magnetic field. This alternating magnetic field excites the cantilever at a second frequency to apply the Bimodal MFM mode. Nonetheless, for ferromagnetic materials with a low coercive field, the external field used in SR-MFM technique can modify the magnetic domains of the sample. In this work, a Hybrid Bimodal MFM (HB-MFM) technique is proposed. In HB-MFM, the bimodal MFM is used, but the first resonance frequency of the cantilever is induced by the magnetic field of the ferromagnetic sample due to its vibrations caused by a piezoelectric element placed under the sample. The advantages of this new technique are demonstrated through the preliminary results obtained by HB-MFM on a hard disk sample. Additionally, traditional two pass MFM and HB-MFM measurements were compared.

Keywords: magnetic force microscopy, atomic force microscopy, magnetism, bimodal MFM

Procedia PDF Downloads 43

Authors: Nurin Amalina Widityani, Adinda Syifa Azhari, Twin Aji Kusumagiani, Eleonora Agustine

Abstract:

Fertilizer industry activities contribute to environmental changes. Changes to the environment became one of a few problems in this era of globalization. Parameters that can be seen as criteria to identify changes in the environment can be seen from the aspects of physics, chemistry, and biology. One aspect that can be assessed quickly and efficiently to describe environmental change is the aspect of physics, one of which is the value of magnetic susceptibility (χ). The rock magnetism method can be used as a proxy indicator of environmental changes, seen from the value of magnetic susceptibility. The rock magnetism method is based on magnetic susceptibility studies to measure and classify the degree of pollutant elements that cause changes in the environment. This research was conducted in the area around the fertilizer plant, with five coring points on each track, each coring point a depth of 15 cm. Magnetic susceptibility measurements were performed by in-situ and ex-situ. In-situ measurements were carried out directly by using the SM30 tool by putting the tools on the soil surface at each measurement point and by that obtaining the value of the magnetic susceptibility. Meanwhile, ex-situ measurements are performed in the laboratory by using the Bartington MS2B tool’s susceptibility, which is done on a coring sample which is taken every 5 cm. In-situ measurement shows results that the value of magnetic susceptibility at the surface varies, with the lowest score on the second and fifth points with the -0.81 value and the highest value at the third point, with the score of 0,345. Ex-situ measurements can find out the variations of magnetic susceptibility values at each depth point of coring. At a depth of 0-5 cm, the value of the highest XLF = 494.8 (x10-8m³/kg) is at the third point, while the value of the lowest XLF = 187.1 (x10-8m³/kg) at first. At a depth of 6-10 cm, the highest value of the XLF was at the second point, which was 832.7 (x10-8m³/kg) while the lowest XLF is at the first point, at 211 (x10-8m³/kg). At a depth of 11-15 cm, the XLF’s highest value = 857.7 (x10-8m³/kg) is at the second point, whereas the value of the lowest XLF = 83.3 (x10-8m³/kg) is at the fifth point. Based on the in situ and exsit measurements, it can be seen that the highest magnetic susceptibility values from the surface samples are at the third point.

Keywords: magnetic susceptibility, fertilizer plant, Bartington MS2B, SM30

Procedia PDF Downloads 315