Field In Different Directions Research Articles

A multi-directional magnetic field sensor based on tapered few mode fiber and magnetic fluid

A multi-directional magnetic field sensor based on tapered few mode fiber and magnetic fluid is proposed via a single mode fiber (SMF)-tapered few mode fiber (TFMF)-SMF structure. Magnetic fluid (MF) is encapsulated outside the TFMF to detect magnetic fields in different directions. The experimental results show that the change trend of the transmission spectrum is related to the direction of the magnetic field, independent of the length of the taper. When a vertical magnetic field is applied to the sensor, the transmission spectrum is red-shifted with the decrease of the magnetic field intensity. When a parallel magnetic field is applied to the sensor, the transmission spectrum is blue-shifted with the decrease of the magnetic field intensity. For the same sensor, the magnetic field sensitivity in vertical direction is significantly higher than that in parallel direction, and can be up to 70,792.85 pm/Oe by applying a magnetic field direction of 180°. The sensor has the advantages of simple fabrication and high sensitivity, and has a good application prospect in scientific research and other magnetic field measurement.

Binding energy and photoionization cross section of hydrogenic impurities in elliptic cylindrical core/shell quantum dots under a non-axial electric field

In this study, a donor impurity confined in an elliptic cylindrical core/shell quantum dot (ECCSQD) under a non-axial electric field is studied by using a variational and perturbation approach. We have investigated the binding energy and corresponding photoionization cross section (PCS) variation with the core and shell sizes, ellipticity constant, impurity position under the non-axial electric field. The results show that the binding energy with elliptic cylinder shape is lower than that with cylinder shape. The influence of electric field in different directions on the binding energy with different impurity positions is completely different. Even though for the on-center impurity, the influence is also very different due to the elliptic cylinder shape. The PCS for the incident radiation propagates perpendicular or parallel to the axis of the ECCSQD are both considered. The results show that the PCS in both causes completely depends on the direction of non-axial electric field and impurity position. In addition, the elliptic cylinder shape also has a significant influence on the peak intensity and position of PCS. • The elliptic cylindrical QD and non-axial electric field are both considered. • Binding energy with elliptic cylinder is lower than that with cylinder. • The PCS for perpendicular or parallel to the axis of the QD are both considered. • The PCS in both causes completely depends on the direction of electric field. • QD shape has a significant influence on the peak intensity and position of PCS.

Dual-Circularly Polarized Topological Patch Antenna With Pattern Diversity

Recently, the topological properties of composite vortices, i.e., the superposition between vortex modes of a different order, have proven effective in manipulating the radiation properties of patch antennas and making them suitable for new operative scenarios. In this paper, we exploit these properties to design a multi-antenna system exhibiting both pattern- and polarization-diversity. The low mutual coupling and the possibility to steer two orthogonal polarized fields in different directions, make this radiating element an optimal candidate for antenna diversity or MIMO systems and, thus, for increasing signal quality or channel capacity of a communication system.

Structure, dynamics, and morphology of nanostructured water confined between parallel graphene surfaces and in carbon nanotubes by applying magnetic and electric fields.

Water molecules experience certain changes in their properties when they feel an external magnetic or electric field. These changes are significant in different applications, such as biological and biotechnological processes, nano-pumping, and water treatment. In this work, we have performed molecular dynamics (MD) simulations to investigate the different thermodynamics, structure, and dynamics of water molecules confined between two parallel surfaces and also confined in carbon nanotubes (CNTs). We have also applied different electric and magnetic fields in different directions to the confined molecules. In the graphene system, no polygonal shape was formed in either low or high electric fields, whereas rhombic and pentagonal shapes were formed in low and high magnetic fields. In the CNT system, applying electric fields in all three dimensions made the pentagonal shape disappear and the confined water molecules formed a ring shape when the electric field was applied in the axial direction. Applying the electric field perpendicular to the graphene surfaces increases the self-diffusion of the confined molecules, whereas applying the electric and magnetic fields along the CNT axis decreases the self-diffusion of the confined water molecules. In the graphene system, applying the electric field perpendicular to the graphene surfaces decreases the average number of hydrogen bonds (〈HB〉) whereas the magnetic field has little effect on the 〈HB〉. In the CNT system, applying Ex also leads to a smaller number of HBs. Also, applying the magnetic field along the x-direction (along the CNT direction) leads to a greater number of HBs than the other fields.

Nonlinear magnetoelectric effects of multiferroic composites

Magnetoelectric effect is one of the most important features in multiferroic composites which is absent in either ferromagnetic or ferroelectric composites. In this paper, a two-level micromechanics model is developed to study the nonlinear magnetoelectric (ME) effects of multiferroic composites consisting both ferromagnetic (or magneto-strictive) and ferroelectric (or piezoelectric) materials. At the first level, the model involves a thermodynamically based evolution of the product domain from the parent one in ferromagnetic phase which provides the nonlinear response of the system under the external loading. And at the second level, it treats the ferromagnetic and ferroelectric as a two-phase composite, and Eshelby based micromechanics is applied to obtain the overall effective properties of the composite. Then the two-level model is used to study the nonlinear magnetoelectric effects of Terfenol-D/PZT/Terfenol-D laminated system under the applied magnetic field first, and then under the combined mechanical and magnetic field in different directions. To verify the model, the theoretical calculations have been compared with the existing experimental data for both single phase Terfenol-D at the first level and the two-phase Terfenol-D/PZT/Terfenol-D multiferroic composite at the second level. The comparisons between the theory and experiment are in a good agreement.

Numerical simulation of MHD natural convection heat transfer in a square cavity filled with Carreau fluids under magnetic fields in different directions

In this paper, the laminar natural convection of non-Newtonian Carreau fluid in a square cavity under uniform magnetic field in different directions is investigated numerically. Based on the projection method, a new finite-difference algorithm on a staggered grid is employed to solve the laminar magnetohydrodynamic natural convection problems, which involves the second-order central scheme for the discretization of non-Newtonian viscous terms. To assess numerical capability of the newly proposed algorithm, the calculation results for Newtonian fluid in the square cavity show excellent agreement with results available in the literature. Research work has been performed for the certain pertinent parameters of Rayleigh number ( $$10^{4}$$ and $$10^{5}$$ ) and Prandtl number ( $$Pr=0.065$$ ) using the new numerical algorithm. The computed results show that the natural convection of Carreau fluid is not only determined by the strength of the magnetic field, but also influenced by the inclination angle. In particular, when the Carreau fluid describes a non-Newtonian fluid, it is found that the inclination angle plays a large role on flow and heat transfer.

Magneto-optical spin Hall effect of light and its application in refractive index detection

The spin Hall effect of light (SHEL) is a photonic version of the spin Hall effect in electronic systems, and it has been a focused research area in the recent ten years. However, due to the lack of effective methods dynamic modulation of spin-dependent splitting, the practical application of SHEL has remained a challenge, still urgently waiting to be resolved. In recent years, SHEL has been applied to the precise measurement and sensing of various physical quantities. Now, how to make SHEL measurement flexible is the research direction of researchers The magneto-optical spin Hall effect of light (MOSHEL) is a useful attempt to implement a dynamic transformation of SHEL. The spin–orbit coupling or non-reciprocal phase shift caused by magnetic fields in different directions applied to magneto-optical materials can be flexibly and timely controlled. This paper reports our studies on the magneto-optical effect in multilayer structure. For the first time, the refractive index of very low concentration sample solution is sensed through the method of weak measurement under the condition of transverse magneto-optical Kerr effect. The ultra-high sensitivity of 2.9×104μm/RIU was measured under the optimum parameters. This is of great significance in advancing the practical application of MOSHEL.

Theoretical study of the structure and properties of Ni/V porphyrins under microwave electric field: A DFT study

Petroporphyrins with nickel (Ni) and vanadium (V) metals in crude oil are harmful to the catalysts of fluid catalytic cracking (FCC) and residue hydrocracking (RHC) as well as their processes. However, the presence of Ni/V as porphyrins makes them extremely difficult to remove. Recently, microwave method has attracted particular interests for high demetallization efficiency of Ni and V compounds from crude oils. In order to achieve better performance, it is indispensable to understand the theory and mechanism of microwave demetallization. The structure and electronic properties of Ni/V porphyrins were hereby studied via the density functional theory with BLYP functional. External electric fields of different directions and intensities were applied in the simulation. The calculation results demonstrated that the activity of pyrrole ring and –CH3 group can be greatly improved by applying parallel electric field (Ex or E−x), whilst the vertical electric field (Ez or E−z) mainly enhanced the activity of metal atoms. It was also found that the deformation mode of the porphyrin ring changed from dome to saddle style when the vertical electric field was larger than 0.025 a.u, meanwhile, the length of Metal-N bond decreased accordingly. This deformation regularity of the spatial structure innovatively explained the existence of an optimum microwave power in experiments.

Multi magnetic states in Co/Cu multilayered cylindrical nanowires studied by combination of off-axis electron holography imaging and micromagnetic simulations

We report on a wide variety of magnetic states in Co/Cu multilayered nanocylinders grown by electrodeposition with different thicknesses of both elements. The remnant magnetic states in individual Co layers have quantitatively been determined at the nanoscale by micromagnetic reconstruction of the magnetic phase shift image obtained by electron holography. We demonstrate that the magnetization in the Co layers can present either uniform or vortex states. Also, different magnetic configurations can be observed within the same nanocylinder. In the case of vortices, the direction of the core can rotate almost at 90° from the nanocylinder axis for layers with an aspect ratio close to 1. We show that the occurrence of each magnetic configuration depends on the aspect ratio of the layers, the direction of magnetocrystalline anisotropy, and, in some cases, the interlayer dipolar coupling. Such a wide variety of magnetic states is observed due to lower values of the Co magnetic constants (magnetization, exchange, anisotropy) with respect to bulk, typical of the electrodeposition process in a single bath, and to the local geometrical variation of the layers. We also calculated the phase diagram of the remnant magnetic states in a single layer for various amplitudes and orientations of the magnetocrystalline anisotropy and different directions of the saturation field. In particular cases, these phase diagrams, in addition to statistics of occurrence of each kind of magnetic configurations in the multilayer and the application of a saturation field in different directions, allow for recovering information on the preferential orientation of the crystalline anisotropy.

Magnetic field controlled hybrid semiconductor and resistive switching device for non-volatile memory applications

A magnetic-field-controlled non-volatile memory device is fabricated by coupling Hall effect and resistive switching effect. The non-volatile property of the device is due to the fact that the Hall voltage of the semiconductor changes the resistance state of the resistive switching unit. By changing the device configuration, the storage can be controlled by magnetic fields in different directions. The parameters of the semiconductors and the resistive switching units are experimentally investigated and simulated to optimize the performance of the devices. The key to increasing the ON/OFF ratio and reducing power consumption is finding a suitable resistance match between the semiconductor and the resistive switching unit. By enhancing the mobility of the semiconductor, the performance of the device can also be significantly improved. This hybrid device provides new insights into the manufacture of magnetic field controlled non-volatile memory devices with potential of integrating computing and storage functions.

Numerical Investigation of Ferrofluid Sloshing by Applying MHD Magnetic Field: Using Level Set Method

The sloshing phenomenon has exceptional significance due to its occurrence in various processes as well as its application. This phenomenon occurs when a vessel is partly filled with a fluid and under the influence of external forces the free surface of the liquid moves and exchanges forces with the wall of the vessel. In this research, numerical modeling is used to study the behavior of ferrofluid in sloshing phenomenon in a rectangular container with a specified length and width of 10 cm × 5 cm respectively. The force that moves the vessel is the oscillatory motion in the x-axis direction. Applying a uniform magnetic force, which creates additional modules in the governing equations, such as the momentum equation, has effects on this phenomenon and fluid motion. The main aim of this research is to study the effects of the uniform MHD field in different directions and angles on the ferrofluid sloshing. By studying the results of some factors (such as; the pressure of the ferrofluid to the specific points on the vessel wall, the maximum surface at any time, and the analysis of the surface situation at different times) the impact of the magnetic field with different angles has been identified on the ferrofluid sloshing. The results showed that in the absence of an external magnetic field, the sloshing behavior of water and ferrofluid were approximately the same. Applying the MHDmagnetic field caused a 14.5%, 25% and 36% decrease in the maximum height of the fluid level at angles 0◦, 45◦ and 90◦ of magnetic field respectively. Therefore, these results indicate the influence of the magnetic field direction on the behavior of the ferrofluid sloshing.

Predicting CO2 residual trapping ability based on experimental petrophysical properties for different sandstone types

To increase confidence in the long-term security of CO2 geologic storage, reliable predictions of the level of post-injection CO2 residual trapping are needed. In this study, we conduct CO2/water coreflooding experiments at reservoir conditions on nine core samples with different degrees and types of heterogeneity to find the best petrophysical properties for predicting sandstone CO2 residual trapping ability. We are able to extract petrophysical properties such as porosity, permeability, degree of mesoscale heterogeneity, and spatial correlation lengths of petrophysical property fields in different directions using a CT scanner. Experimental results show that CO2 residual trapping ability decreases with porosity and increases with the degree of heterogeneity. A number of metrics for heterogeneity are evaluated, including the Dykstra-Parsons coefficient and the variance in voxel-level CO2 drainage saturation fields as well as the porosity and permeability fields. The variance of the saturation distribution during drainage provides the best predictor of residual gas trapping. By extrapolating the relationship between the degree of heterogeneity and the linear trapping coefficient, we show that pore-scale trapping mechanisms account for 46–97% of the residually trapped CO2 and the mesoscale capillary heterogeneity trapping mechanism accounts for 3–54% of the residually trapped CO2 for the nine sandstone samples tested.

Absorption and quantum coherence of a degenerate two-level system in the presence of a transverse magnetic field in different directions

We investigate the absorption spectra for the ${F}_{g}=1\ensuremath{\rightarrow}{F}_{e}=0$ transition of the ${D}_{2}$ line of $^{87}\mathrm{Rb}$ excited by a linearly polarized light in the presence of a transverse magnetic field (TMF) in different directions. Using the theoretical methods in quantum optics, we obtain the analytical expressions for the atomic density-matrix elements and the absorption spectrum. We analyze the splitting proportional to the magnitude of the TMF in the coherent population trapping absorption spectrum and explain its physical origin. Then, the sensitivity of the resonance signal to the phase (in our case, to the angle between the TMF and the light polarization) is investigated. We show and explain the splitting of the bright resonance and find the simple dependence of the separation of this splitting on the magnitude and the direction of the TMF. Therefore, this system may provide a possible method for the measurement of the magnetic field vector. In addition, we study the coherence of the system based on an observable coherence measure, namely, robustness of coherence (ROC). We find that in the case where the absorption signal becomes difficult to detect, the change of the ROC spectrum becomes more obvious and the extreme points are well maintained. Therefore, this may provide a scheme for the measurement of the magnetic field which is complementary to that based on the absorption signal of the laser.

The effect of external magnetic field on the linear stage evolution of Kelvin–Helmholtz instability in laser driven plasma

A Kelvin–Helmholtz instability (KHI) is a fundamental physical process of fluids and magnetized plasma. We report the experimental formation of a KHI produced by intense laser-driven thin plastic foils. For an external magnetic field in different directions, the KHI shows different evolutionary features. A theoretical derivation shows that an external magnetic field has a stronger effect on KHI growth when its component is perpendicular to the plasma flow. A linear evolutionary stage of the KHI is captured by optimizing the target design, which is reproduced by FLASH simulation.

Vibration of two-dimensional hexagonal boron nitride

ABSTRACT The dynamic behavior of two-dimensional nanostructures is important to the future application of nano devices. The vibrational behaviors of single-layered hexagonal boron nitride (h-BN) are studied by molecular dynamics simulation and continuum plate model. The bending stiffness and Poisson's ratios of h-BN along zigzag direction and armchair direction are calculated. H-BN is softer compared with graphene. The continuum plate model can predict the vibration of h-BN with four edge-clamped boundary conditions well. The electric fields in different directions have obvious influence on the vibration of h-BN. The natural frequency of h-BN changes linearly with the electric field intensity along the polarization direction. The natural frequency of h-BN decreases with the increase of electric field intensity along both positive and negative non-polarization direction. While the natural frequency of h-BN increases with the increase of electric field intensity along both positive and negative transverse electric field.

Zebrafish “personality” influences sensitivity to magnetic fields

How animals integrate different sensory information for orientation is a complex process involving interactions between a variety of internal and external factors. Due to this complexity, each component of a suite of factors is typically studied in isolation. Here, we examine how an internal factor (personality of fish) influences the response of zebrafish (Danio rerio) to the magnetic field, while swimming in a flow chamber. Our previous work demonstrated that the orientation to the water current (rheotaxis) of zebrafish individuals is influenced by variations of the magnetic field only when fish are part of a shoal. In this study, we evaluated the rheotactic behavior of 20 fish, grouped in shoals of “proactive” or “reactive” individuals, under magnetic fields of different directions. We found that the magnetic field influenced at which water speed rheotaxis was elicited in zebrafish with “reactive” personality, but not in those with “proactive” personality. These results suggest that fish personality influences response to or weighing of sensory inputs and provides some insight on the variation in behavioral responses to environmental stimuli in both laboratory and natural settings.

Synthesis, optical, experimental and theoretical investigation of third order nonlinear optical properties of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate single crystal

Single crystals of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate (8HQNP) were obtained from slow evaporation solution growth method using methanol-water (1:1) as a solvent. Powder X-ray diffraction was utilized to compute the unit cell parameters and dislocation density of 8HQNP crystal. The crystalline perfection of the as-grown crystal was investigated by high-resolution X-ray diffraction at room temperature. The molecular structure was analyzed by identifying the functional groups from FT-IR and FT-Raman spectra. The cut-off wavelength and the corresponding optical band gap obtained from an optical spectrum were 376 nm and 3.29 eV respectively. The dispersion nature of refractive index was investigated by the single-oscillator Wemple and Di-Domenico model. Red emission was observed in the photoluminescence spectrum when excited with 376 nm. The low birefringence and high laser damage threshold (8.538 GW/cm2) values dictate the suitability of the crystal for optical devices. Z-scan studies revealed the third order nonlinear absorption coefficient (β) and refractive index (n2) of the 8HQNP crystal. The theoretical value of third order nonlinear susceptibility obtained from density function theory is good accordance with the experimental value. The frontier molecular orbital energy gap decreases with increasing external electric field in different directions which attributed to the enhancement of the second hyperpolarizability. The grown title crystal is thermally stable up to 102 °C which was identified using thermal analysis. Mechanical strength of 8HQNP was estimated by using Vicker's microhardness studies.

Compensation for Magnetic Disturbances in Motion Estimation to Provide Feedback to Wearable Robotic Systems.

The direction of the Earth's magnetic field is used as a reference vector to determine the heading in orientation estimation with wearable sensors. However, the magnetic field strength is weak and can be easily disturbed in the vicinity of ferromagnetic materials, which may result in inaccurate estimate of orientation. This paper presents a novel method for estimating and compensating for magnetic disturbances. The compensation algorithm is implemented within a kinematic-based extended Kalman filter and is based on an assessment of the magnetic disturbance and the change of orientation in each time step. The proposed algorithm was experimentally validated by measuring the orientation of a simple mechanical system with three degrees of freedom in an artificially disturbed magnetic field. The results of the experimental evaluation show that an Kalman filter algorithm that incorporates compensating for magnetic disturbances is capable of estimating the orientation with moderate error (the absolute median errors , ) when the Earth's magnetic field is disturbed by magnetic disturbance with a magnitude equal to twice the magnitude of the Earth's own magnetic field in different directions.

The origin of the LMC stellar bar: clues from the SFH of the bar and inner disc

Abstract We discuss the origin of the Large Magellanic Cloud (LMC) stellar bar by comparing the star formation histories (SFHs) obtained from deep colour–magnitude diagrams (CMDs) in the bar and in a number of fields in different directions within the inner disc. The CMDs, reaching the oldest main-sequence turn-offs in these very crowded fields, have been obtained with VIMOS on the Very Large Telescope in the service mode, under very good seeing conditions. We show that the SFHs of all fields share the same patterns, with consistent variations of the star formation rate as a function of time in all of them. We therefore conclude that no specific event of star formation can be identified with the formation of the LMC bar, which instead likely formed from a redistribution of disc material which occurred when the LMC disc became bar unstable, and shared a common SFH with the inner disc thereafter. The strong similarity between the SFH of the centre and edge of the bar rules out the expected significant spatial variations of the SFH across the bar.

Simulation of the influence of constant uniform magnetic field on a miniature LIT mass spectrometer.

In this paper, the effects of constant uniform magnetic fields on a miniature linear ion trap mass spectrometer with hyperbolic electrodes are simulated using SIMION 8.0 3D software. Magnetic fields in different directions have different effects on the trajectories of the trapped ions and the shape of the ion cloud. When the magnetic field is applied in the z-direction, namely the ion injection direction, the magnetic field will cause the ions focusing to the z-axis, and exert a compression effect on the ion cloud. When the magnetic field is applied in the x-y plane, the original ion cloud will be expanded due to the action of the applied magnetic field, and the ion cloud plane after expansion is always perpendicular to the direction of the magnetic field. The discovery of influence field of magnetic will bring some useful inspiration for the improvement of ion trapping efficiency, mass resolution, sensitivity and trapping capacity, which is conductive to the performance enhancement utilization of magnetic field, even in the industrial application development and other aspects.