Magnetic Stress Research Articles

Optimal design of high-speed permanent magnet synchronous generator based on NSGA-II considering mechanical properties

Although the finite element method (FEM) is highly reliable, it is time-consuming and expensive, for example, substantial computing costs are incurred for coupled analysis while considering the mechanical and electromagnetic properties. Therefore, in this paper, a high-speed permanent magnet generator's electromagnetic and stress characteristics have been mathematically derived, and the optimal point is selected based on NSGA-II. The objective functions are power density and efficiency, with the constraints being the current density, slot fill factor, core saturation, voltage limit, and rotor safety factor. The method presented in this study was verified via FEM analysis and experimental results of the optimal model.

Response to Magnetic Field-Induced Stress on the Demographics and anti-ROS Activity of Aphid Macrosiphum rosae L. (Hemiptera:Aphididae)

Magnetic field plays an essential role for many species, including the migratory pest aphid. Our previous study investigated the long-term exposure of static magnetic fields on the growth development and productivity of the aphid Macrosiphum rosae, however, it is necessary to expand the knowledge of short-term exposure on the insects for a wider spectrum of magnetic field radiation. To achieve this, aphid nymphs were exposed to four magnetic field of induction at 0.065T, 0.1T, 0.176T and 0.28T for 4min under laboratory conditions. The results showed that the short-term magnetic radiation significantly prelonged the four instar development while shortened the first, second and third instar period. 0.28 T radiations caused significantly difference in the parameters of TPOP, adult longevity and total longevity (3.2d, 7.07d, and 8.82d, compared with the control of 4.94d, 8.06d, and 10.23d, respectively). Population parameter of r was 0.057d-1 with 0.28 T compared with the control of 0.150 d-1. The SOD, CAT and POD activity increased more than 30% in static magnetic fields compared with the controls. Our study presents a feasible evidence showing the growth development change as a representative disturbing symptom for short-term exposure to magnetic fields, and the static magnetic field applied being capable of modifying the fitness components and antioxidant defense in aphids.

Analytical solutions of the magnetic and stress fields on a soft ferromagnetic material containing a smooth rigid inclusion in two-dimensional space

The analytical investigations on a rigid inclusion embedded in a soft ferromagnetic material in two-dimensional space subjected to uniform magnetic load at infinity have been carried out, with the magnetic insulation boundary of the rigid inclusion. In our study, explicit solutions of the magnetic and stress fields are obtained based on linear magnetoelastic theory and complex variable theory. The relative rigid-body displacement of the rigid inclusion is considered to ensure the boundary condition and constraint satisfied accurately. It is found that the analytic solutions of Kolosov-Muskhelishvili (K-M) potentials have a compact form when the shape of rigid inclusion is characterized by Laurent polynomial with finite terms. As examples, the rigid-body displacement, magnetic flux and stress on the boundary of elliptic and polygonal rigid inclusions are analyzed, respectively. Our results show that the rigid-body displacement caused by a non-strong magnetic load is small, while the orientation and contour curvature of the rigid inclusions have significant effects on the distribution of the stress and magnetic flux fields. In addition, the maximum magnetic flux and maximum stress do not always occur at the maximum curvature point. For polygonal rigid inclusions, the orientations in which the extreme concentration is obtained are closely related to the number of tips of the inclusions.

Impact of interface stress on responsive deformation of magnetic hydrogel

A multiphysics model is presented to study the responsive deformation of the magnetic hydrogel subject to a magneto-chemo-mechanical coupled field. In this work, the influences of the surrounding solvent and the magnetic stress at the hydrogel-surrounding interface are particularly investigated on the performance of the magnetic hydrogel. The physicochemical processes of mass transfer, force balance, and magnetization are included. The constitutive relations are derived by the second law of thermodynamics, and the free energy density is proposed with nonlinear magnetization. The coupled partial differential equations are numerically solved by the finite element method. After that, the deformation patterns are compared with or without the interface stress, and then various parametric studies are performed to investigate the effects of the magnetic susceptibility, geometric shape, and surrounding size on the responsive deformation of the magnetic hydrogel. Results show that the interface stress contributes significantly to the final deformation pattern of the magnetic hydrogel, and the performance of the deformable magnetic hydrogel can be precisely controlled. The present findings offer predictive insights into the deformation mechanism of the magnetic hydrogel, and also provide guidance for developing the programmable magnetic hydrogel-based device.

Magnetic resonance imaging-based hemodynamic wall shear stress alters aortic wall tissue biomechanics in bicuspid aortic valve patients

ObjectiveIn this study we aimed to conclusively determine whether altered aortic biomechanics are associated with wall shear stress (WSS) independent of region of tissue collection. Elevated WSS in the ascending aorta of patients with bicuspid aortic valve has been shown to contribute to local maladaptive aortic remodeling and might alter biomechanics. MethodsPreoperative 4-dimensional flow magnetic resonance imaging was performed on 22 patients who underwent prophylactic aortic root and/or ascending aorta replacement. Localized elevated WSS was identified in patients using age-matched healthy atlases (n = 60 controls). Tissue samples (n = 78) were collected and categorized according to WSS (elevated vs normal) and region. Samples were subjected to planar biaxial testing. To fully quantify the nonlinear biomechanical response, the tangential modulus (local stiffness) at a low-stretch (LTM) and high-stretch (HTM) linear region and the onset (TZo) and end stress of the nonlinear transition zone were measured. A linear mixed effect models was implemented to determine statistical relationships. ResultsA higher LTM in the circumferential and axial direction was associated with elevated WSS (P = .007 and P = .018 respectively) independent of collection region. Circumferential TZo and HTM were higher with elevated WSS (P = .024 and P = .003); whereas the collection region was associated with variations in axial TZo (P = .013), circumferential HTM (P = .015), and axial HTM (P = .001). ConclusionsThis study shows strong evidence that biomechanical changes in the aorta are strongly associated with hemodynamics, and not region of tissue collection for bicuspid valve aortopathy patients. Elevated WSS is associated with tissue behavior at low stretch ranges (ie, LTM and TZo).

Multilayer Heterogeneous Membrane Biosensor Based on Multiphysical Field Coupling for Human Serum Albumin Detection.

A factor closely associated with renal disease status in clinical diagnosis is abnormal human serum albumin (HSA) concentration levels in human body fluids urine, serum, etc. The surface stress biosensor was developed as a new type of biosensor to detect protein molecule concentration and has a wide range of clinical applications. However, further sensitivity improvement is required to achieve higher detection performance. Herein, MXene/PDMS/Fe3O4/PDMS of the multilayer heterogeneous membrane biosensor (MHBios) based on the coupling of the magnetic field, electric field, and surface stress field was successfully developed to achieve high sensitivity HSA detection through magnetic sensitization. The modified antibody specifically binds to HSA at the AuNP layer, allowing the biosensor to convert the surface stress caused by PDMS film deformation into an electrical signal. When the biosensor was exposed to a uniform magnetic field, the conductive path of the conductive layer was reshaped further as the magnetic force amplified the deformation of the PDMS film, enhancing the conversion of biological signals to electrical signals. The results exhibited that the detection limit (LOD) of the MHBios was 78 ng/mL when HSA concentration was 0-50 μg/mL, which was markedly lower than the minimum diagnostic limit of microalbuminuria. Furthermore, the MHBios detected HSA in actual samples, confirming the potential for early disease screening.

Numerical treatment of thermal and concentration convection along with induced magnetic field on peristaltic pumping of a magnetic six-constant Jeffrey nanofluid through a vertical divergent channel

This article presents a computational study for the peristaltic pumping within vertical irregular divergence channels filled with magnetic six-constant Jeffrey nanofluids. Various configurations of the outer boundaries are considered, namely, square wave, trapezoidal wave, multisinusoidal wave, and triangular wave. An induced magnetic field together with nanoparticles and mass concentration are considered. Influences of the Dufour and Soret numbers are examined, and the cases of long wavelength and low Reynolds number are applied. All the computations are obtained numerically via MATHEMATICA symbolical software (built-in command ND-Solve), and the obtained results are presented in terms of the axial velocity current density the function of magnetic force axially induced magnetic field nanoparticle fraction profile concentration profile temperature profile extra stress tensor pressure gradient pressure rise and stream function The major outcomes revealed that the square wave shape gives higher pressure gradients near the inlet and outlet parts while the multisinusoidal wave gives periodic behaviors of Also, higher axial-induced magnetic fields are given at the higher values of the magnetic Reynolds number.

Расчет магнитоупругих датчиков со сложным напряженным состоянием магнитопровода

Рассмотрена методика расчета магнитоупругих датчиков, где магнитная проницаемость материала магнитопровода является тензором, приращения компонентов которого пропорциональны компонентам тензора механических напряжений. Зависимость между компонентами тензоров напряжений и приращений магнитной проницаемости линейна и описывается двумя параметрами магнитоупругой чувствительности, определяющимися экспериментально для конкретного материала по специальной методике. Приращение индукции в точке магнитопровода пропорционально как приращению компонентов тензора магнитной проницаемости, так и приращению напряженности магнитного поля вследствие ее перераспределения между участками магнитной цепи. Использована аппроксимация магнитной цепи датчика схемами замещения, участки которых имеют сосредоточенные параметры. Приведены примеры использования методики для расчета различных типов магнитоупругих датчиков.

Environment and physical performance of the athlete

The state of health of the athlete, the level of work capacity, the quality of life and its duration depend significantly on the quality of filling the components of the environment. Constant stay in an ecologically clean, healthy and safe environment contributes to prolonging life and increasing sports performance. At the same time, environmental pollution has a negative effect on the athlete. From these positions, the determination of harmful factors plays an important role. It is known that the environment is the environment in which certain objects function, including air, water, and soil. This work presents data on physical, chemical and biological factors of negative air, water and soil pollution on the body of athletes. Exceeding the maximum permissible norms of these pollution components can become the causes of illness and shorten the life expectancy of an athlete. Therefore, in our opinion, this work will serve as a basis for ensuring the organization of the athlete's professional activities in a healthy environment.
 Among the components that require control of their quantity and quality are solid physical compounds, air temperature and humidity, the presence and natural level of radioactivity, magnetic field stress, and others. Hygienic standards have been established for all physical, chemical, and biological negative factors — maximum permissible concentrations. All indicators, doses, and levels require monitoring. Taking into account the fact that it is not advisable for athletes to stay in polluted areas, the location of sports facilities in these areas is also not desirable. Pollution of air, water, and soil also negatively affects buildings of various functional purposes, vehicles in which athletes are located. Therefore, a differentiated approach is needed when choosing a location, a site for the construction of sports facilities, training and competitions of athletes. To use it, it is necessary to know the negative effects of the complex as a whole on the changed properties of air, soil, water and each component separately. Some data related to the questions were reflected in this work.

Inverse identification of pipeline steel mechanical state by means of coupled magnetic measurements and artificial neural networks

Artificial neural networks are widely used to develop models able to predict properties of interest by learning and establishing relationships between inputs and outputs of a system. It is particularly relevant for the inversion process in the framework of Non-Destructive Testing (NDT) involving strongly non-linear and non-monotonic behavior and/or saturations. The case-study considered in this work is a magnetic material subjected to uniaxial mechanical stress, plastic strain and magnetic field. An Artificial Neural Networks (ANN) model is proposed to predict the corresponding remanent magnetization, coercive field and the maximum magnetization as target properties. A series of experimental data made of various magneto-mechanical measurements are used to train, evaluate and validate the ANN model. The proposed model suitably predicts the magnetic properties of a second specimen of the material in the same magnetic field, plastic strain and stress ranges as the first specimen. An inverse ANN is then proposed to evaluate the mechanical loading and the plastic strain from the magnetic signature. Unique and accurate solutions are found that proves the relevance of machine learning approach in such NDT application.

Alternating North‐South Brightness Ratio of Ganymede's Auroral Ovals: Hubble Space Telescope Observations Around the Juno PJ34 Flyby

AbstractWe report results of Hubble Space Telescope observations from Ganymede's orbitally trailing side which were taken around the flyby of the Juno spacecraft on 7 June 2021. We find that Ganymede's northern and southern auroral ovals alternate in brightness such that the oval facing Jupiter's magnetospheric plasma sheet is brighter than the other one. This suggests that the generator that powers Ganymede's aurora is the momentum of the Jovian plasma sheet north and south of Ganymede's magnetosphere. Magnetic coupling of Ganymede to the plasma sheet above and below the moon causes asymmetric magnetic stresses and electromagnetic energy fluxes ultimately powering the auroral acceleration process. No clear statistically significant timevariability of the auroral emission on short time scales of 100s could be resolved. We show that electron energy fluxes of several tens of mW m−2 are required for its OI 1,356 Å emission making Ganymede a very poor auroral emitter.

Effect of Stress on Variations in the Magnetic Field of Ferromagnetic Steel under a Constant DC Magnetic Field

In this paper, variations in the normal component of the magnetic field BZ on the surface of Q195 steel specimens produced by simultaneous application of noncoaxial DC magnetic field and stress were studied by tensile tests. It was found that there was no shift in the direction of BZ variations when the specimens were magnetized parallel to stress, whereas the direction of BZ variations shifted a slight angle relative to the DC magnetic field when the specimens were magnetized perpendicular to stress. The amplitude of BZ increased with stress from 0 MPa to 120 MPa when the stress was parallel to the DC magnetic field. On the contrary, the amplitude of BZ decreased with stress from 0 MPa to 120 MPa when the stress was perpendicular to the DC magnetic field. The mechanisms underlying the experimental characteristics are also discussed. This research provides the possibility for quantitative inspection of the stress in ferromagnetic steels using surface magnetic field measurements.

STUDY OF FACTORS INFLUENCING THE WALL SLIP OF A MAGNETORHEOLOGICAL FLUID

The wall slip of magnetorheological (MR) fluids refers to a phenomenon that affects the application of mechanical properties of magnetorheological fluids due to the relative slippage between the magnetic particles and the transmission wall. In this paper, we analyze and experimentally verify the factors affecting the wall slip of magnetorheological fluids, which can limit the application of magnetorheological-fluid devices. Firstly, from the theoretical point of view, it is considered that the influencing factors are mainly divided into two parts: magnetorheological fluid’s own parameters and transmission surface roughness, among which the parameters include viscosity, mass fraction, etc. When studying the influence of the transmission surface roughness, it is found that different surface morphologies have a great influence on the shear stress. Secondly, a magnetic field simulation analysis and shear yield stress experiments are conducted on shear blocks with different surface morphologies; the obtained results are compared and verified, confirming that different surface shapes affect the shear yield stress by changing the magnetic field distribution of the groove, which in turn changes the wall slip characteristics. These findings provide an effective basis for further research on the wall slip of magnetorheological fluids to improve the transmission effect.

Leakage detection in natural gas pipeline based on unsupervised learning and stress perception

Natural gas pipeline leakage can cause serious financial losses to natural gas transportation and pose accidents to the environmental safety. Currently-used supervised learning methods heavily rely on sufficient pipeline failure historical data for their training. Therefore, we propose a novel detection approach based on unsupervised learning and stress perception for determining the leakage situation in pipelines. In this study, pipeline stress signals are first acquired based on residual magnetic effect. The relationship between residual magnetic and stress is built using improved sparrow search algorithm (ISSA) and extreme learning machine (ELM). Then, the Wasserstein generative adversarial network with gradient penalty (WGAN-GP) is deployed to learn suitable features from the stress signals under the pipeline normal condition, generating high-quality stress data features. Finally, the generated stress features are supplied to the Bayesian Gaussian mixture model (BGMM). And the weighted logarithm probability (WLP) is used as the health indicator for examining pipeline status. The results demonstrate that the relative error of residual magnetic stress model is controlled within 3 %, and the WLP value of fault samples is smaller than − 100, so that the proposed method can discriminate the normal and leak conditions as well as the risk and severity of leakage. This study provides a theoretical basis and new perspective for pipeline leakage detection.

Quasiperiodic Erupters: A Stellar Mass-transfer Model for the Radiation

Quasiperiodic erupters are a remarkable class of objects exhibiting very-large-amplitude quasiperiodic X-ray flares. Although numerous dynamical models have been proposed to explain them, relatively little attention has been given to using the properties of their radiation to constrain their dynamics. Here we show that the observed luminosity, spectrum, repetition period, duty cycle, and fluctuations in the latter two quantities point toward a model in which a main-sequence star on a moderately eccentric orbit around a supermassive black hole periodically transfers mass to the Roche lobe of the black hole; orbital dynamics lead to mildly relativistic shocks near the black hole; and thermal X-rays at the observed temperature are emitted by the gas as it flows away from the shock. Strong X-ray irradiation of the star by the flare itself augments the mass transfer, creates fluctuations in flare timing, and stirs turbulence in the stellar atmosphere that amplifies the magnetic field to a level at which magnetic stresses can accelerate infall of the transferred mass toward the black hole.

Low frequency tail of gravitational wave spectra from hydromagnetic turbulence

Hydrodynamic and magnetohydrodynamic turbulence in the early Universe can drive gravitational waves (GWs) and imprint their spectrum onto that of GWs, which might still be observable today. We study the production of the GW background from freely decaying magnetohydrodynamic turbulence from helical and nonhelical initial magnetic fields. To understand the produced GW spectra, we develop a simple model on the basis of the evolution of the magnetic stress tensor. We find that the GW spectra obtained in this model reproduce those obtained in numerical simulations if we consider the detailed time evolution of the low-frequency tail of the stress spectrum from numerical simulations. We also show that the shapes of the produced GW frequency spectra are different for helical and nonhelical cases for the same initial magnetic energy spectra. Such differences can help distinguish helical and nonhelical initial magnetic fields from a polarized background of GWs -- especially when the expected circular polarization cannot be detected directly.

Treatment of Knee Dislocation With Primary Repair and Suture Augmentation: A Viable Solution.

Different surgical techniques have been described for the treatment of knee dislocation (KD). Nonoperative approaches are frequently combined with surgical reconstruction using auto- or allograft. To evaluate the midterm results of primary surgical repair and suture augmentation to treat KD. Case series; Level of evidence, 4. A total of 22 patients (5 women, 17 men; mean age, 45 ± 15 years) with KD were evaluated at a mean of 49 ± 16 months after surgical treatment that included primary repair and suture augmentation. Magnetic resonance imaging, stress radiographs, and outcome scores were obtained at the follow-up. Clinical examination including hop tests and force measurements for flexion and extension was performed. The mean difference in pre- to postinjury Tegner scores was -2 ± 1. The outcome scores showed mean values of 84 ± 15 (Lysholm), 73 ± 15 (International Knee Documentation Committee) and 65 ± 25 (Anterior Cruciate Ligament-Return to Sport after Injury scale). Compared with the uninjured knee, the range of motion of the injured knee was reduced by 21° ± 12°. Twelve patients felt fit enough to perform hop tests and showed a mean deficit of 7% ± 17%° compared with the uninjured leg. The mean force deficit was 19% ± 18% for extension and 8% ± 16% for flexion. Stress radiographs revealed an 11 ± 7-mm higher anteroposterior translation on the injured side. Four patients had secondary ligament reconstructions due to persistent instability and 7 underwent arthroscopic arthrolysis due to stiffness. A significant increase of osteoarthritis was found for the medial, lateral, and patellofemoral compartments (P = .007, .004, and .006, respectively). Primary repair and suture augmentation of KD led to satisfactory clinical midterm results despite persistent radiological instability and a significant increase in osteoarthritis. This technique allows the return to activities of daily living without subjective instability in most nonathletic patients. Secondary ligament reconstructions should be performed if relevant instability persists to decrease the risk of secondary meniscal and cartilage damage.

Discontinuous shear thickening (DST) transition with spherical iron particles coated by adsorbed brush polymer

We explore the rheology of very concentrated (0.55 < Φ < 0.67) suspensions of carbonyl iron particles coated by a small polymer. A strong discontinuous shear thickening (DST) is observed in a large range of volume fraction presenting some specific behaviors in comparison with other systems. In particular, the DST transition can appear suddenly without being preceded by shear thickening. The presence of a frictional network of particles is confirmed by a simultaneous measurement of the electric resistance of the suspension and of the rheological curve. Using the Wyart–Cates (W–C) model, we show that with increasing the volume fraction, the fraction of frictional contacts increases more quickly with the stress, contrary to the prediction of numerical simulations. The same behavior is observed in the presence of a magnetic field with a strong increase in the viscosity before the DST transition. We interpret this behavior by the interpenetration of the polymer layer under the effect of the shear stress—and of the magnetic stress—followed by the expulsion of the polymer out of the surfaces between two particles in contact. We point out that above the DST transition, we do not observe a jamming in the range of volume fraction, whereas it is predicted by the W–C model. The frictional contacts are created by a shear stress and not by a static stress, so in the absence of shear flow, the polymer can adsorb again on the surface and lubricate the frictional contacts. We thus predict an asymptotic non-zero shear rate reproducing the experimental behavior.

The Effect of Nanoflare Flows on EUV Spectral Lines

The nanoflare model of coronal heating is one of the most successful scenarios to explain, within a single framework, the diverse set of coronal observations available with the present instrument resolutions. The model is based on the idea that the coronal structure is formed by elementary magnetic strands which are tangled and twisted by the displacement of their photospheric footpoints by convective motions. These displacements inject magnetic stress between neighboring strands that promotes current sheet formation, reconnection, plasma heating, and possibly also particle acceleration. Among other features, the model predicts the ubiquitous presence of plasma flows at different temperatures. These flows should, in principle, produce measurable effects on observed spectral lines in the form of Doppler shifts, line asymmetries and nonthermal broadenings. In this work we use the two-dimensional cellular automaton model (2DCAM) developed in previous works, in combination with the enthalpy-based thermal evolution of loops (EBTEL) model, to analyze the effect of nanoflare heating on a set of known EUV spectral lines. We find that the complex combination of the emission from plasmas at different temperatures, densities and velocities, in simultaneously evolving unresolved strands, produces characteristic properties in the constructed synthetic lines, such as Doppler shifts and nonthermal velocities up to tens of km s−1 for the higher analyzed temperatures. Our results might prove useful to guide future modeling and observations, in particular, regarding the new generation of proposed instruments designed to diagnose plasmas in the 5–10 MK temperature range.

Prediction of Rotor Slot Size Variations in Induction Motor Using Polynomial Chirplet Transform and Regression Algorithms

For constant monitoring of rotor slot in induction motor, average rotor slot variation (ARSV) prediction is proposed. The rotor slots expand due to thermal stress and high intensity magnetic flux. The magnetic flux with high intensity is created in rotor lamination sheet, because of stretching and curving magnetic flux. The surface of rotor slot exhibits thermal stress due to over current which in turn generates heat and transfers the heat into the rotor lamination surface. The magnetic stress-based rotor slot size variation is never monitored or measured before. In the proposed ARSV method, multimodal sensor signals such as Giant magnetoresistance, temperature, current, vibration and voltage acquire magnetic stress and temperature stress of rotor. The acquired signals are analyzed through polynomial chirplet transform to obtain energy band values of signal. The energy band values and microscopic camera image-based rotor slot variation values are used for ARSV prediction. The prediction of ARSV is computed using polynomial regression (PR) method. From experimental results, it is observed that ARSV is greater than 5% from the normal size which leads to extreme damage to the motor through vibration, sparking and harmonics. The prediction accuracy of ARSV is about 94.6% when compared to manual measurement of slots in rotor. Moreover, the prediction of ARSV avoids the major faults, namely eccentricity, overload, under voltage, unbalance voltage, induced rotor slot, rotor crack and rotor burn.