Field Strength Parameter Research Articles

Application of pre-magnetic separation to address grinding classification density effects and enhance iron-copper separation in deep polymetallic magnetite ores

This study investigates the challenges faced in the grinding and classification process of a polymetallic magnetite ore from Anhui, particularly focusing on low classification efficiency, significant over-grinding, and decreased metal recovery rates. By analyzing the mineralogical properties of the ore, specifically mineral composition, intergrowth relationships, intergrowth particle size, and liberation degree, with an emphasis on magnetite, chalcopyrite, cobalt minerals, and precious metal minerals, this research aims to identify the underlying causes of these issues. Subsequent single-factor experiments were conducted to assess the effects of magnetic field strength and grinding parameters on the enrichment of magnetite and chalcopyrite. Under optimal processing conditions, with a magnetizing current of 0.25 A and a grinding fineness of 65% passing through a 200-mesh sieve, the application of butyl xanthate as a collector during mixed rough flotation achieved a copper recovery rate of 89.54%. Building on these findings, the study further discusses the impact of various process flow optimizations on grinding, classification operations, and the recovery of target minerals. Additionally, it evaluates the advantages and disadvantages of different processing methods in practical applications and ultimately proposes a suitable mineral processing flow for intermediate to deep ore deposits.

Nanosized Eu3+-Doped NaY9Si6O26 Oxyapatite Phosphor: A Comprehensive Insight into Its Hydrothermal Synthesis and Structural, Morphological, Electronic, and Optical Properties.

Detailed analysis covered the optical and structural properties of Eu3+-doped NaY9Si6O26 oxyapatite phosphors, which were obtained via hydrothermal synthesis. X-ray diffraction patterns of NaY9Si6O26:xEu3+ (x = 0, 1, 5, 7, 10 mol% Eu3+) samples proved a single-phase hexagonal structure (P63/m (176) space group). Differential thermal analysis showed an exothermic peak at 995 °C attributed to the amorphous to crystalline transformation of NaY9Si6O26. Electron microscopy showed agglomerates composed of round-shaped nanoparticles ~53 nm in size. Room temperature photoluminescent emission spectra consisted of emission bands in the visible spectral region corresponding to 5D0 → 7FJ (J = 0, 1, 2, 3, 4) f-f transitions of Eu3+. Lifetime measurements showed that the Eu3+ concentration had no substantial effect on the rather long 5D0-level lifetime. The Eu3+ energy levels in the structure were determined using room-temperature excitation/emission spectra. Using the 7F1 manifold, the Nv-crystal field strength parameter was calculated to be 1442.65 cm-1. Structural, electronic, and optical properties were calculated to determine the band gap value, density of states, and index of refraction. The calculated direct band gap value was 4.665 eV (local density approximation) and 3.765 eV (general gradient approximation). Finally, the complete Judd-Ofelt analysis performed on all samples confirmed the experimental findings.

Mechanical properties of silicone polymer with magnetic filler in magnetic field

Purpose. To investigate the change in the mechanical properties of a magnetorheological silicone elastomer consisting of a polymer filled with magnetite nanoparticles under the influence of an inhomogeneous magnetic field of an electromagnet. Methods. The experiments were carried out on a magnetic response research facility developed and manufactured independently based on known methods. The value of the deflection angle of the magnetically active receiver was determined by the optical method. Two-component silicone rubbers filled with magnetite particles were studied as samples. The manufactured samples differed in geometric dimensions, magnetic phase concentrations of 1%, 5%, 10% and 20%, and polymerization mechanism. The source of the magnetic field was electromagnets of various sizes connected to power sources. The images were captured using a Micmed 5.0 digital USB microscope.Results. The analysis of the structure of the manufactured magnetorheological silicone elastomers was carried out, as well as studies of the effect of the magnetic field strength and sample parameters on the deflection angle of the magnetically active cantilever. A theoretical interpretation of the obtained results is proposed.Conclusion. The experimental dependence of the tilt angle of a magnetically active polymer cantilever on the equilibrium position relative to the magnitude of the magnetic field strength of the electromagnet is determined. The obtained research results can be used to develop actuators and magnetoactive sensors.

Modeling of micropolar hybrid nanofluids flow across porous medium between permeable parallel plates with nonlinear thermal radiative in MHD

The study pertains on the dynamics and thermal distribution of magnetohydrodynamics (MHD) micropolar hybrid nanofluids flowing between two parallel plates channel. It explores the enhancement of heat transport processes by blending the base fluid with nanoparticles at varying concentrations. A system of nonlinear partial differential equations is developed as governing equations for momenta and heat energy. To facilitate numerical solutions for fluid temperature and velocities, this formulation is translated into ordinary differential form using the necessary similarity transformation. By utilizing Matlab code for the Runge–Kutta method and shooting approach, we evaluate the results. It has been observed that an increase in the concentration of hybrid nanoparticles enhance the heat transmission. The salient findings of this study reveal alteration in the velocity profiles for both nanofluid (SWCNT/water) and hybrid nanofluids (SWCNT + MWCNT/water) flow. Notably, with a substantial input of magnetic field strength (M) and porosity parameters (P0), the velocity is increased near the walls but it decelerates toward the center of channel. Additionally, the temperature rises for hybrid nanofluids. Furthermore, an increase in the θ w temperature ratio parameter leads to an enhanced thermal distribution.

Electrical Characteristics of the Insulation Paper Modified by Nano-TiO2 under Electrical-Thermal Aging

The research on the modified insulating paper by adding nano-materials has garnered increasing attentions. Scholars have investigated its performances under electrical aging or thermal aging, but there are few reports on its behaviors under electrical-thermal combined aging. In the laboratory, we prepared the modified insulating paper with different mass fractions of nano-TiO2, and subjected to 10-day accelerated electrical-thermal combined aging test. Samples were experimented at different aging stages to investigate the variations in AC breakdown field strength, relative permittivity and surface microstructure. The results demonstrate that the modified insulating paper samples exhibit better AC breakdown field strength, relative permittivity and other parameters compared to the unmodified samples. Among the modified samples, the one with 3% mass fraction of nano-TiO2 shows the best electrical properties and aging resistance under electrical-thermal combined aging. By adding an appropriate weight percentage of nano-TiO2, it was able to fill microscopic holes and gaps on the surface of the insulating paper, strengthen the connection between the cellulose fibers, and improve the electrical properties and aging resistance of the insulating paper.

Optical-pump-terahertz-probe spectroscopy in high magnetic fields with kHz single-shot detection.

We demonstrate optical pump-THz probe (OPTP) spectroscopy with a variable external magnetic field (0-9T), in which the time-dependent THz signal is measured by echelon-based single-shot detection at a repetition rate of 1kHz. The method reduces data acquisition times by more than an order of magnitude compared to conventional electro-optic sampling using a scanning delay stage. The approach illustrates the wide applicability of the single-shot measurement approach to non-equilibrium systems that are studied through OPTP spectroscopy, especially in cases where parameters such as magnetic field strength (B) or other experimental parameters are varied. We demonstrate the capabilities of our measurement by performing cyclotron resonance experiments in bulk silicon, where we observe B-field-dependent carrier relaxation and distinct relaxation rates for different carrier types. We use a pair of economical linear array detectors to measure 500 time points on each shot, offering an equivalent performance to camera-based detection with possibilities for higher repetition rates.

On the Possibility of an Upper Limit on Magnetically Induced Radius Inflation in Low-mass Stars

The radii of low-mass stars are observed to be inflated above standard model predictions, especially in magnetically active stars. Typically, the empirical relative radius inflations ΔR/R are ≤10% but in (rare) cases may be ≥20%. Our magneto-convective stellar models have already replicated many empirical ΔR/R values. Here, we ask: is there any theoretical upper limit on the amount of such inflation? We use our magneto-convective model to compute ΔR/R using empirically plausible values of the surface field strength parameter δ. Inside each model, the maximum internal field is set to a particular value: B ceil = 10, or 100 kG, or 1 MG. When B ceil = 10 kG, peak inflation with ΔR/R ≈ 90% occurs in stars with masses of 0.7 M ⊙. With B ceil = 100 kG, peak inflation with ΔR/R ≈ 140% occurs in stars with M ≈ 0.5 M ⊙. But with B ceil = 1 MG, we find no peak in ΔR/R as a function of δ; instead, the larger δ is, the larger ΔR/R becomes, reaching 300%–350% in the case of the largest δ considered. Thus, magneto-convective modeling can accommodate ΔR/R values which are considerably larger than any reported empirical inflations. We find that a maximum occurs in ΔR/R as a function of δ only in model stars where the field reaches its maximum strength B ceil inside the convective envelope. Moreover, our models of completely convective stars undergo smaller amounts of relative radius inflation than models with radiative cores, a result consistent with some previous reports.

Simultaneous effects of the position dependent mass and magnetic field on quantum well with the improved Tietz potential

In this study, we explored the synergistic impact of position-dependent mass and magnetic field on the electronic and optical properties of quantum wells, featuring an enhanced Tietz potential confinement incorporating both standard Morse and improved Rosen–Morse potentials, as influenced by variations in the structural parameter. Calculations were conducted within the framework of effective mass and parabolic band approximations. The diagonalization method was employed, selecting a wave function basis of trigonometric orthonormal functions to determine the eigenvalues and eigenfunctions of the confined electron potential. Our findings reveal that alterations in the sizes and shapes of the quantum wells, magnetic field strength, geometric asymmetry, and confinement parameters lead to significant variations in electron energies, transition between electron states, and the absorption spectrum. These outcomes offer valuable insights for investigating the electronic and structural properties of materials and devising novel materials with tailored optical characteristics.

Mason number modified for magnetorheological fluid dynamic characteristics

A quantitative analysis of characteristics of a magnetorheological fluid (MRF) under dynamic oscillation conditions was conducted using the Mason number method. The expression for the modified dynamic Mason number Mn* under different vibration frequencies, vibration amplitudes, and magnetic field strengths was established through theoretical derivations. The energy storage and loss moduli of the MRF were measured using dynamic sweep-amplitude experiments under different oscillation conditions. The results revealed that the data of the energy storage and loss moduli can be collapsed into the main curve when the dynamic Mason number Mn* is regarded as the abscissa. Furthermore, the function of each modulus and Mn* was obtained by data fitting. Thus, a unified mathematical model for MRF moduli vs. magnetic field strength and oscillatory parameters such as frequency, amplitude, et al. was established. This will provide support for the application of the MRF in vibration control and other fields.

Mathematical modeling of blood flow in an annulus porous region between two coaxial deformable tubes: An advancement to peristaltic endoscope

In the present work, the electromagnetohydrodynamic peristaltic flow of blood through an annulus region between two concentric circular tubes has been investigated for the advancement of a peristaltic endoscope. In this model, the viscous and incompressible blood is assumed as non-Newtonian Jeffery fluid, and tubes are inclined at an angle β with the horizontal. The governing equations for the considered problem are simplified under the assumption of a low Reynolds number and long wavelength approximations. An analytical expression for various flow variables such as axial velocity, radial velocity, time mean flow rate, volumetric flow rate, frictional force at the surface of the inner tube, and mechanical efficiency is obtained. In this work, we discussed the impact of various flow parameters like the Hartmann number M, electric field strength parameter H, Jeffery fluid parameter λ1, radius ratio n, occlusion ϕ=ba, angle of inclination β, and Darcy number Da on the above flow variables. The streamlines are also made to discuss the trapping phenomena of a fluid bolus inside the tubes. The comparison of pressure rise for the various endoscopes and the validation of the present result with the previously established results are discussed.

Magnetic feature and regression analysis of Reiner-Philippoff boundary layer flow

The design and optimization of magnetic fluid-based processes, such as magnetohydrodynamic power generation and magnetic drug targeting, have become significant in recent times. To understand the magnetic and radiation features, as well as the sensitivity of engineering physical quantities to each dimensionless parameter in fluid flow, the Reiner-Philippoff (RP) fluid is best suited in this instance, as it exhibits shear-thickening, shear-thinning, and Newtonian behavior. The non-similar transformation is used to transform the partial differential equations that describe the flow into two-variable differential equations. The transformed dynamical equations are solved numerically using a spectral-based numerical technique; namely, the bivariate simple iteration method (BSIM). The effects of magnetic field strength and radiation parameter on the stretching and shrinking sheets are examined. The investigation reveals that both the magnetic field strength and radiation parameter have a significant impact on the flow behavior and rate of heat transfer. For the radiation parameter R∈[0,0.5], the skin friction coefficient and Nusselt number increase by 22.6% and 5.98%, respectively. Additionally, an 100% increment in Prandtl parameter reduces the Nusselt number by 287.36%. Regression analysis is performed to identify the most significant parameter affecting the engineering quantities. The results show that the Bingham constant, γ, is the only parameter that is not significant on the skin friction coefficient, while all the parameters have significant impact on the Nusselt number. The findings in this study have important implications in the biomedical industry, the design of machines, and the fourth industrial revolution.

Boltzmann thermometer with broadband emission in Mn4+-Doped β-Ga2O3 crystals

The luminescence properties of Mn4+-doped β-Ga2O3 are strongly affected by the surrounding crystal field within the [MnO6] octahedral site, which is substitute for GaⅡ site, as determined through the first-principles calculations. The crystal field strength parameters Dq, B, and C are computed, and the Tanabe-Sugano diagram is redrawn for C/B = 6.7. The temperature dependence of the optical spectra is thoroughly examined, revealing the thermal quenching mechanisms involving the thermal activation energy of 2Eg and 4T2g, which are 378 ± 26 cm−1 and 3527 ± 25 cm−1, respectively. In order to further investigate the temperature sensing characteristics, the absolute (Sa) and relative (Sr) sensitivities are obtained. At 303 K, the Sr is determined to be 0.72 %K−1, while Sa is estimated to be in the range of 10−2 (below 0.05 K-1) for the Mn4+ doped β-Ga2O3 thermometers. The thermal resolution δT is demonstrated to be below 0.1 K, surpassing that of traditional Nd3+ and Er3+-doped thermometers. Moreover, a linear relationship between the energy separation ΔE of the thermally coupled 2Eg-4T2g energy levels and the crystal field strength Dq is observed in numerous materials. With this consideration, the nature of the thermometer, along with its Sa and Sr, can be roughly predicted and designed for various operational conditions.

Bonding and Magnetic Trends in the [AnIII(DPA)3]3- Series Compared to the Ln(III) and An(IV) Analogues.

The crystal field parameters are determined from first-principles calculations in the [AnIII(DPA)3]3- series, completing previous work on the [LnIII(DPA)3]3- and [AnIV(DPA)3]2- series. The crystal field strength parameter follows the Ln(III) < An(III) < An(IV) trend. The parameters deduced at the orbital level decrease along the series, while J-mixing strongly impacts the many-electron parameters, especially for the Pu(III) complex. We further compile the available data for the three series. In some aspects, An(III) complexes are closer to Ln(III) than to An(IV) complexes with regard to the geometrical structure and bonding descriptors. At the beginning of the series, up to Pu(III), there is a quantitative departure from the free ion, especially for the Pa(III) complex. The magnetic properties of the actinides keep the trends of the lanthanides; in particular, the axial magnetic susceptibility follows Bleaney's theory qualitatively.

Synergistic effect of dual-site occupation and activators confinement realizing an efficient ultra-broadband NIR emitter

Broadband near-infrared (NIR) phosphor-conversion light-emitting diode (pc-LED) devices have an extensive application prospect in night vision monitoring, nondestructive testing, and biomedical imaging. In this work, the ultra-broadband NIR emission produced by the chromium-activated NaZn(PO3)3 phosphor with two-site occupation peaks at around 900 nm with a full width at half-maximum (FWHM) of 218 nm. Time-resolved spectroscopic techniques and steady-state fluorescence spectra coupled with crystal structure confirm the multiple occupations of the chromium ion. Notably, the NaZn(PO3)3: Cr3+ phosphors exhibit an internal quantum efficiency (IQY) of 80.6 % and an external quantum efficiency (EQY) of 35.4 %, which may originate from the activators confinement, direct band-gap property, and high absorbance. To better comprehend the connection between structure and luminescence capabilities, the band structure, crystal field strength parameters, fluorescence lifetime, and thermal stability were all thoroughly investigated. Finally, the optimal sample has demonstrated its application in the quantitative analysis of ethanol/water mixtures. The results provide a novel perspective for the rational design of desired emitters.

Attenuation characteristics analysis of the THz circularly polarized waves in inhomogeneous fully ionized dusty plasma using FPL model

When the hypersonic vehicle is flying, the plasma in the area near the stagnation point of the front end of the vehicle can be approximately seen as the fully ionized dusty plasma. Due to the existence of dust particles, dusty plasma affects the communication quality of the hypersonic vehicle. In this paper, the general Boltzmann equation applicable to dusty plasmas containing electrons and the Fokker–Planck–Landau collision model are combined to derive a general formula for the electron distribution function of fully ionized dusty plasmas. Considering the contribution of the collision effect and charging effect to the dispersion relationship of fully ionized dusty plasma, the dielectric constant of fully ionized dusty plasma under an external magnetic field is solved. The Wentzel–Kramers–Brillouin method is used to calculate the attenuation coefficient (α) of the THz wave in fully ionized dusty plasma, and the influence of the external magnetic field strength and other dusty plasma parameters on the attenuation characteristics of the THz circularly polarized wave is analyzed. The research results show that the α of the THz left-hand circularly polarized wave decreases with the increase in the external magnetic field strength, while the α of the THz right-hand circularly polarized wave increases. In addition, increasing the dust particle radius, dust particle density, and electron density in a certain frequency range can increase the α of the THz circularly polarized waves. These research results provide theoretical guidance for the exploration of the interaction mechanism between the THz waves and fully ionized dusty plasma.

Effect of inhomogeneous magnetoelectric interaction on flat magnetic structures

In this work, we theoretically study the effect of inhomogeneous magnetoelectric interaction on the distribution of magnetization in insulating ferromagnetic films with strong easy-plane anisotropy. It is shown that, depending on the magnitude of the applied electric field, structures of various topologies can form in such films. It has been established that the optimal control of the magnetic structure can be achieved by the field of a charged filament. For this case, all stable and metastable states of the system are studied in detail depending on the field strength and material parameters of the film.

Structure, Luminescence and Temperature Detection Capability of [C(NH2)3]M(HCOO)3 (M = Mg2+, Mn2+, Zn2+) Hybrid Organic-Inorganic Formate Perovskites Containing Cr3+ Ions.

Metal-organic frameworks are of great interest to scientists from various fields. This group also includes organic-inorganic hybrids with a perovskite structure. Recently their structural, phonon, and luminescent properties have been paid much attention. However, a new way of characterization of these materials has become luminescence thermometry. Herein, we report the structure, luminescence, and temperature detection ability of formate organic-inorganic perovskite [C(NH2)3]M(HCOO)3 (Mg2+, Mn2+, Zn2+) doped with Cr3+ ions. Crystal field strength (Dq/B) and Racah parameters were determined based on diffuse reflectance spectra. It was shown that Cr3+ ions are positioned in the intermediate crystal field or close to it with a Dq/B range of 2.29-2.41. The co-existence of the spin-forbidden and spin-allowed transitions of Cr3+ ions enable the proposal of an approach for remote readout of the temperature. The relative sensitivity (Sr) can be easily modified by sample composition and Cr3+ ions concentration. The luminescent thermometer based on the 2E/4T2g transitions has the relative sensitivity Sr of 2.08%K-1 at 90 K for [C(NH2)3]Mg(HCOO)3: 1% Cr3+ and decrease to 1.20%K-1 at 100 K and 1.08%K-1 at 90 K for Mn2+ and Zn2+ analogs, respectively.

Structural transition in a ferroelectric nano-dispersed cholesteric liquid crystal

ABSTRACT We present a theoretical study of the orientational and electrical behaviors of a cholesteric liquid crystal dispersed with ferroelectric nanoparticles. We assume a soft planar coupling between the liquid crystal molecules and the nanoparticles. We consider two spiral structures in the ferroelectric nano-dispersed system under an external electric field. This assumption is due to the fact that the director and the polarization vector would have different pitches of spiral structure. We study the behavior of the average polarization and the pitch of the helical structure as a function of the field strength. The impact of ferroelectric nanoparticles on cholesteric-nematic phase transition is investigated by calculating the critical electric field. The influence of field strength and material parameters on the phase transition is also discussed. The calculations are based on a developed continuum theory and a modified form of free energy for the helical supramolecular structure. The influence of nanoparticle volume fraction on the helix unwinding of both spiral structures is studied. It is found that an electric field with a sufficiently high strength causes an increase in the pitch of the helical structure of polarization. We obtain a critical volume fraction of nanoparticles, after which the pitch of the polarization helical structure differs from the director pitch.

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

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

Prevalence of White Matter Hyperintensities in Young Adults With and Without Mild Traumatic Brain Injury (S28.004)

<h3>Objective:</h3> To determine the prevalence and severity of white matter T2 hyperintensities (WMHs) in young healthy adults and those with recent mild traumatic brain injury (mTBI). <h3>Background:</h3> WMHs on T2-weighted (T2W) MRI are common. Normative data on their prevalence in young healthy adults and in the setting of mTBI is not well characterized, and dependent upon classification system, MRI field strength, scan resolution and imaging parameters. <h3>Design/Methods:</h3> High-resolution 3-Tesla 3D T2W FLAIR and SWI images were retrospectively reviewed from 602 mTBI and control patients who participated in a larger multicenter study of advanced neuroimaging biomarkers. All scans were independently reviewed by 2 board-certified blinded neuroradiologists. All patients with WMHs were identified; patients with excessive WMHs were also identified if ≥5 objective, punctate, white matter foci were present or lesions were &gt;3 mm or atypical in location. <h3>Results:</h3> 413 patients with documented mTBI and 189 controls were analyzed. 32% (134/413) of the mTBI patients and 40% (76/189) of the control patients demonstrated at least 1 WMH on high-resolution T2W-FLAIR imaging. Of these patients, 34% (45/134) of the mTBI group and 34% (26/76) of the control group demonstrated ≥5 lesions, one &gt;3 mm lesion, or lesions in atypical locations. There was no significant difference in number of patients with at least 1 WMH (p=0.064) or excessive WMHs (p=0.313) between mTBI and control groups. <h3>Conclusions:</h3> This represents the largest study cohort of mTBI patients and healthy controls assessing the prevalence of WMHs on high-resolution 3-Telsa 3D T2W-FLAIR. Prevalence of WMHs did not differ between groups and were observed at higher rates than reported in the current literature. These results reflect an evidence-based need to reassess our understanding and clinical interpretation of WMHs in normal healthy adults and patients with mTBI. <b>Disclosure:</b> Dr. Shetty has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Biohaven Pharmaeucticals. Dr. Shetty has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for mTBI, Inc. The institution of Dr. Shetty has received research support from Marker AG. The institution of Dr. Shetty has received research support from Teva Pharmaceuticals Industry. The institution of Dr. Shetty has received research support from GE-NFL. Mr. Westafer has nothing to disclose. Joseph T Nguyen has received personal compensation in the range of $0-$499 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for The American Journal of Sports Medicine. Joseph T Nguyen has received personal compensation in the range of $0-$499 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for The Women’s Journal of Sports Medicine. Miss Coffey has nothing to disclose.