Single-phase diluted magnetic systems Zn1-xFexO have been prepared by chemical route. Structural and spectroscopic （UV-Vis and Mossbauer） studies indicate the incorporation of Fe^3＋ ions in the lattice sites. The U...Single-phase diluted magnetic systems Zn1-xFexO have been prepared by chemical route. Structural and spectroscopic （UV-Vis and Mossbauer） studies indicate the incorporation of Fe^3＋ ions in the lattice sites. The UV-Vis results point to a systematic increase in the band gap with increasing Fe doping. The room temperature magnetization of Zni-xFexO indicates a paramagnetic behavior which is in accordance with the Mossbauer results, illustrating quadrupolar doublet. At low temperature, the zero-field-cooled （ZFC） magnetization shows a cusp and this temperature increases systematically with decreasing particle size. The weak exchange bias effect manifested by a M-H loop shift is observed for x = 0.03. This shift is accompanied by the enhancement of coercivity. The dc magnetization results suggest the coexis tence of ferromagnetic and antiferromagnetic exchange interactions for low doping of Fe, i.e., for x = 0.03.展开更多
In this paper, we present a comprehensive investigation of the effects of the transverse correlation function （TCF） on the thermodynamic properties of Heisenberg antiferromagnetic （AFM） and ferromagnetic （FM） sy...In this paper, we present a comprehensive investigation of the effects of the transverse correlation function （TCF） on the thermodynamic properties of Heisenberg antiferromagnetic （AFM） and ferromagnetic （FM） systems with cubic lattices. The TCF of an FM system is positive and increases with temperature, while that of an AFM system is negative and decreases with temperature. The TCF lowers internal energy, entropy and specific heat. It always raises the free energy of an FM system but raises that of an AFM system only above a specific temperature when the spin quantum number is S 〉 1. Comparisons between the effects of the TCFs on the FM and AFM systems are made where possible.展开更多
Polarized magnetic system has a series of features, such as small volume, light weight, low power consumption, high sensitivity, quick movement and so on, widely used in the products of the military aerospace electrom...Polarized magnetic system has a series of features, such as small volume, light weight, low power consumption, high sensitivity, quick movement and so on, widely used in the products of the military aerospace electromagnetic relay. The typical polarized magnetic system has mainly four structures and its simplified equivalent magnetic circuits model is the base of the design of the electromagnetic relay with permanent magnet. In the past, the analysis method that people used was difficult to build the unified mathematical models, which divided the work gap magnetic flux into "permanent magnet flux" and "electromagnetic flux". Based on the analysis method of the work gap magnetic voltage, this paper founds the unified mathematical model of the polarized magnetic system and divides the attractive torque into permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula. It analyses the influence of permanent magnet sizes on permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula and the conclusions can direct the design of aerospace electromagnetic relay with permanent magnet.展开更多
The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the differ...The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the single-ion anisotropy are included, our results indicate that there are compensation points at finite temperatures. When the next-nearest-neighbor interaction exceeds a minimum value that depends on the other parameters in the Hamiltonian, the compensation point disappears. The next-nearest-neighbor interaction has the effect of changing the compensation temperature.展开更多
Modeling of permanent magnet（PM） is very important in the process of electromagnetic system calculation of aerospace electromagnetic relay（AEMR）. In traditional analytical calculation, PM is often equivalent to a ...Modeling of permanent magnet（PM） is very important in the process of electromagnetic system calculation of aerospace electromagnetic relay（AEMR）. In traditional analytical calculation, PM is often equivalent to a lumped parameter model of one magnetic resistance and one magnetic potential, but great error is often caused for the inner differences of PM; based on the conception of flux tube, a type of 2D magnetic equivalent circuit framework of permanent magnet model（2D MECF） is established; the element is defined, the relationship between elements is deduced, and solution procedure as well as verification condition of this model is given; by a case study of the electromagnetic system of a certain type of AEMR, the electromagnetic system calculation model is established based on 2D MECF and the attractive force at different rotation angles is calculated; the proposed method is compared with the traditional lumped parameter model and finite element method（FEM）; for some types of electromagnetic systems with symmetrical structure, 2D MECF proves to be of acceptable accuracy and high calculation speed which fit the requirement of robust design for AEMR.展开更多
A new design of stato magnetic System is Proposed for 3-phase & 12-pole HB stepper, and it features bet-ter distribution of magntic lield to incare Pullou tope and bopmve Operaonal stability of moor and minimummut...A new design of stato magnetic System is Proposed for 3-phase & 12-pole HB stepper, and it features bet-ter distribution of magntic lield to incare Pullou tope and bopmve Operaonal stability of moor and minimummutual inductance between phase windimp to make design of control circuit easier, and application proved it is as good as expected.展开更多
The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequ...The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z|J|,DB/z|J|) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z|J| and DB/z|J|. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.展开更多
The mixed spin-3/2 and spin-2 Ising ferrimagnetic system with different single-ion anisotropies in the absence of an external magnetic field is studied within the mean-field theory based on Bogoliubov inequality for t...The mixed spin-3/2 and spin-2 Ising ferrimagnetic system with different single-ion anisotropies in the absence of an external magnetic field is studied within the mean-field theory based on Bogoliubov inequality for the Gibbs free energy. Second-order critical lines are obtained in the temperature-anisotropy plane. Tricritical line separating second-order and first-order lines is found. Finally, the existence and dependence of a compensation points on single-ion anisotropies is also investigated for the system. As a result, this mixed-spin model exhibits one, two or three compensation temperature depending on the values of the anisotropies.展开更多
Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.Wi...Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.With accurate descriptions of the ground states and low-energy excitations of(quasi-)one-dimensional(1D)quantum spin models,significant progress has been made in studying quantum criticality and related emergent physics.In this review,we provide a short survey on some recent developments in this field.We start by discussing critical thermodynamics and dynamics of transverse-field Ising chain,highlighting novel quantum integrability and many-body excitations upon relevant perturbations.Dynamical properties of the excitations are further discussed,along with their experimental verification.Along the line of integrability,we further discuss the Heisenberg-Ising chain,introducing the string magnetic state.Among them,non-trivial string solutions which go beyond conventional field theory,have also been observed in experiments.Apart from the critical phenomena associated with the standard Ginzburg-Landau paradigm,we introduce the deconfined quantum criticality,which arises as a consequence of a continuous phase transition between two ordered states.Such a transition goes beyond the description of the Ginzburg-Landau paradigm and is characterized by the emergence of fractionalized spin excitations and enhanced continuous symmetry at the quantum critical point.Finally,we conclude by highlighting potential novel critical phenomena and emergent physics and their realizations in quasi-1D quantum magnetic systems.展开更多
This study presents preliminary results of tidal-induced magnetic field signals extracted from 9 months of data collected by the Macao Science Satellite-1(MSS-1) from November 2023 to July 2024. Tidal signals were iso...This study presents preliminary results of tidal-induced magnetic field signals extracted from 9 months of data collected by the Macao Science Satellite-1(MSS-1) from November 2023 to July 2024. Tidal signals were isolated using sequential modeling techniques by subtracting non-tidal field model predictions from observed magnetic data. The extracted MSS-1 results show strong agreement with those from the Swarm and CryoSat satellites. MSS-1 effectively captures key large-scale tidal-induced magnetic anomalies, mainly due to its unique 41-degree low-inclination orbit, which provides wide coverage of local times. This finding underscores the strong potential of MSS-1 to recover high-resolution global tidal magnetic field models as more MSS-1 data become available.展开更多
Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embed...Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embedded in the capsule accurately in advance,which can cause inconvenience to practical application.To solve this problem,this paper proposes a magnetic tracking system with the capability of measuring themagnetic moment of the PM automatically.The system is constructed based on a 4×4 magnetic sensor array,whose sensing data is analyzed to determine the magnetic moment by referring to a magnetic dipole model.Withthe determined magnetic moment,a method of fusing the linear calculation and Levenberg-Marquardt algorithmsis proposed to determine the 3D position and 2D attitude of the PM.The experiments verified that the proposedsystem can achieve localization errors of 0.48 mm,0.42 mm,and 0.83 mm and orientation errors of 0.66◦,0.64◦,and 0.87◦for a PM(∅10 mm×10 mm)at vertical heights of 5 cm,10 cm,and 15 cm from the magnetic sensorarray,respectively.展开更多
Dear Editor,Active magnetic bearings(AMBs)are of considerable interest and significance in smart manufacturing due to their zero-friction and adaptivity to noncontact rotor rotations.This paper proposes an active levi...Dear Editor,Active magnetic bearings(AMBs)are of considerable interest and significance in smart manufacturing due to their zero-friction and adaptivity to noncontact rotor rotations.This paper proposes an active levitation control algorithm based on adaptive sliding mode control(ASMC)equipped with linear extended state observer(LESO).Sufficient conditions are derived to guarantee the asymptotical stability of the associated closed-loop system.Experiments are conducted on a real AMB-rotor platform to demonstrate the effectiveness and superiority of the proposed algorithm.展开更多
BACKGROUND Trichotillomania is a challenging to treat psychiatric disorder,with limited evidence for pharmacotherapy.Treatment typically involves medication,cognitive behavioral therapy,and behavioral interventions.Re...BACKGROUND Trichotillomania is a challenging to treat psychiatric disorder,with limited evidence for pharmacotherapy.Treatment typically involves medication,cognitive behavioral therapy,and behavioral interventions.Recently,transcranial magnetic stimulation(TMS)has emerged as a potential treatment strategy.AIM To assess the role of TMS in treating trichotillomania.METHODS A systematic search using specific terms was done in PubMed and Scopus databases for articles published until May 17,2024,related to trichotillomania and TMS.The search included randomized controlled trials,open-label studies,case series,case reports,and retrospective chart reviews,following the Preferred Items for Systematic Reviews and Meta-Analysis guideline.RESULTS We identified 32 articles(6 in PubMed and 26 in Scopus).After removing duplicates and articles that did not meet the selection criteria,we conducted a final analysis of four articles.These included one retrospective study,two case series,and one case study,with a total of 22 patients diagnosed with trichotillomania enrolled across all four studies.The brain areas targeted were the supplementary motor area(SMA),pre-SMA,and left dorsolateral prefrontal cortex.The studies reported an improvement in the severity of symptoms of trichotillomania in the majority of patients with negligible side effects.Nevertheless,it is important to note that the existing studies are mostly of low to moderate quality.CONCLUSION Early evidence suggests repetitive TMS and accelerated continuous theta burst stimulation can help treat trichotillomania adjunctively to other treatments.展开更多
Magnetic resonance imaging(MRI)plays an important role in medical diagnosis,generating petabytes of image data annually in large hospitals.This voluminous data stream requires a significant amount of network bandwidth...Magnetic resonance imaging(MRI)plays an important role in medical diagnosis,generating petabytes of image data annually in large hospitals.This voluminous data stream requires a significant amount of network bandwidth and extensive storage infrastructure.Additionally,local data processing demands substantial manpower and hardware investments.Data isolation across different healthcare institutions hinders crossinstitutional collaboration in clinics and research.In this work,we anticipate an innovative MRI system and its four generations that integrate emerging distributed cloud computing,6G bandwidth,edge computing,federated learning,and blockchain technology.This system is called Cloud-MRI,aiming at solving the problems of MRI data storage security,transmission speed,artificial intelligence(AI)algorithm maintenance,hardware upgrading,and collaborative work.The workflow commences with the transformation of k-space raw data into the standardized Imaging Society for Magnetic Resonance in Medicine Raw Data(ISMRMRD)format.Then,the data are uploaded to the cloud or edge nodes for fast image reconstruction,neural network training,and automatic analysis.Then,the outcomes are seamlessly transmitted to clinics or research institutes for diagnosis and other services.The Cloud-MRI system will save the raw imaging data,reduce the risk of data loss,facilitate inter-institutional medical collaboration,and finally improve diagnostic accuracy and work efficiency.展开更多
After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to ...After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to magnetic fields,have poor compatibility,and are difficult to adapt to various types of magnets.This paper proposes a new field measuring system based on a three-axis movable platform.The system utilizes non-magnetic materials and an innovative hand-wheel lifting design that can be adapted to various aperture magnets,thus obviating the necessity for electrically driven equipment and addressing safety concerns in strong magnetic fields.In addition,the measurement system offers high accuracy up to 1 mm and a wide measurable range.The fields of 3 T and 7 T magnets were mapped using the designed system with diameter of spherical volume(DSV)of 160 mm and 130 mm,respectively.Experimental results demonstrate that the magnetic field measurement system has strong compatibility and can accurately map the magnetic field at arbitrary positions,which is critical for shimming studies.展开更多
Cooling system design applicable to more than one photovoltaic(PV)unit may be challenging due to the arrangement and geometry of the modules.Different cooling techniques are provided in this study to regulate the temp...Cooling system design applicable to more than one photovoltaic(PV)unit may be challenging due to the arrangement and geometry of the modules.Different cooling techniques are provided in this study to regulate the temperature of conductive panels that are arranged perpendicular to each other.The model uses two vented cavity systems and one L-shaped channel with ternary nanofluid enhanced non-uniform magnetic field.Their cooling performances and comparative results between different systems are provided.The finite element method is used to conduct a numerical analysis for a range of values of the following:the strength of themagnetic field(Hartmann number(Ha)between 0 and 50),the inclination of the magnetic field(γbetween 0 and 90),and the loading of nanoparticles in the base fluid(ϕbetween 0 and 0.03),taking into account both uniformand non-uniformmagnetic fields.For the L-shaped channel and vented cavities,vortex size is controlled by imposing magnetic field and adjusting its strength.Whether uniform or non-uniform magnetic field is applied affects the cooling performances for different cooling configurations.Temperature drops of the horizontal panel with different magnetic field strengths by using channel cooling,vented cavity-1 and vented cavity-2 systems for uniformmagnetic are 11℃,21.5℃,and 3℃when the reference case of Ha=0 is considered for the same cooling systems.However,they become 9.5℃,13.5℃,and 12.5℃when nonuniform magnetic field is used.In the presence of uniform magnetic field effects and changing its magnitude,the use of cooling channel in vented cavity-1 and vented cavity-2 systems results in temperature drops of 4℃,10.8℃,and 3.8℃for vertical panels.On the other hand,when non-uniform magnetic field effects are present,they become 0.5℃,2.1℃,and 9℃.For L-channel cooling,the average Nu for the horizontal panel is more affected byγ,andNu rises asγrises.With increasing nanoparticle loading of ternary nanofluid,the average panel surface temperature shows a linear drop.For the horizontal panel,the temperature declines for nanofluid at the highest loading are 4℃,10℃,and 12℃as compared to using only base fluid.The values of 5℃,7℃,and 11℃are obtained for the vertical panel.Different cooling systems’performance is estimated using artificial neural networks.The method captures the combined impact of applying non-uniformmagnetic field and nanofluid together on the cooling performancewhile accounting for varied cooling strategies for both panels.展开更多
[Objectives]To evaluate the effects of repetitive transcranial magnetic stimulation(rTMS)on neurophysiological outcomes in patients with acute stroke.[Methods]A systematic literature search was conducted across PubMed...[Objectives]To evaluate the effects of repetitive transcranial magnetic stimulation(rTMS)on neurophysiological outcomes in patients with acute stroke.[Methods]A systematic literature search was conducted across PubMed,EMBASE,Web of Science,the Cochrane Central Register of Controlled Trials(CENTRAL),and CINAHL databases up to March 1,2025.Randomized controlled trials(RCTs)and clinical controlled trials(CCTs)involving adult patients(≥18 years)with acute ischemic stroke(within 2 weeks of onset)who received rTMS intervention were included.Data on motor evoked potential(MEP)amplitude,resting motor threshold(RMT),and central motor conduction time(CMCT)were extracted.The quality of the studies was assessed using the Cochrane risk of bias tool.Statistical analyses were performed using Stata 18.0,with standardized mean differences(SMDs)and 95%confidence intervals(CIs)calculated.Heterogeneity was evaluated using the I^(2)statistic.[Results]Eight studies involving 932 identified records met the inclusion criteria.Meta-analysis revealed that rTMS significantly increased MEP amplitude(Hedges'g=0.77,95%CI:0.52-1.02,P<0.01)and reduced RMT(Hedges g=-1.13,95%CI:-1.63 to-0.62,P<0.01)in the lesioned hemisphere,indicating enhanced corticospinal excitability.No significant effects were observed on MEP amplitude or RMT in the unaffected hemisphere.Additionally,rTMS did not significantly alter CMCT in either hemisphere.Heterogeneity was low to moderate for most outcomes,and no significant publication bias was detected.[Conclusions]rTMS is a safe and effective intervention for improving corticospinal excitability and motor recovery in patients with acute stroke.Both high-frequency stimulation of the ipsilesional hemisphere and low-frequency stimulation of the contralesional hemisphere have demonstrated beneficial effects,supporting the interhemispheric inhibition model.Future large-scale,multi-center RCTs are needed to optimize rTMS parameters and establish standardized treatment protocols for acute stroke rehabilitation.展开更多
Objective:Although bariatric surgeries are widely performed around the world,patients frequently experience the recurrence of pre-existing gastroesophageal reflux disease(GERD)symptoms or develop new symptoms,some of ...Objective:Although bariatric surgeries are widely performed around the world,patients frequently experience the recurrence of pre-existing gastroesophageal reflux disease(GERD)symptoms or develop new symptoms,some of which are resistant to medical treatment.This study investigates the effect and outcome of magnetic sphincter augmentation(MSA),a minimally invasive treatment for GERD,in this population.Methods:A thorough search of the PubMed,Cochrane,Scopus,Web of Science,and Google Scholar databases from inception until June 6,2024 was performed to retrieve relevant studies that evaluated the effects of MSA on the GERD health-related quality of life(GERD-HRQL)score and the reduction in proton pump inhibitor(PPI)use in patients who underwent bariatric surgery.The“meta”package in RStudio version 2023.12.0 t 369 was used.Results:A total of eight studies were included in the systematic review and seven studies were included in the meta-analysis.MSA significantly reduced the GERD-HRQL score(MD?27.55[95%CI:30.99 to24.11],p<0.01)and PPI use(RR?0.23[95%CI:0.16 to 0.33],p<0.01).Conclusion:MSA is a viable treatment option for patients with GERD symptoms who undergo bariatric surgery.This approach showed promising results in terms of reducing the GERD-HRQL score and reducing the use of PPI.展开更多
Background:Building upon our previous work that developed a folate receptor-mediated,euphaorbia factor L1-loaded PLGA microsphere system integrating active and magnetic targeting for theranostics,further investigation...Background:Building upon our previous work that developed a folate receptor-mediated,euphaorbia factor L1-loaded PLGA microsphere system integrating active and magnetic targeting for theranostics,further investigation into its in vivo pharmacokinetics and tissue distribution is warranted despite its demonstrated biocompatibility and safety.Methods:A UPLC-MS/MS method was established to determine the concentration of euphorbia sterol in rat plasma and mouse tissue homogenates,healthy male SD rats and KM mice were administered in groups,drug concentrations at different time points were determined,pharmacokinetic parameters were analyzed by DAS software,and data were processed by SAS software.Results:The proposed method met the requirements of biological sample detection.The plasma pharmacokinetics of rats showed that the drug concentration in the microsphere group was lower than that in the injection group,and the parameters such as mean residence time(MRT(0–t)),half-life(T1/2z)and apparent volume of distribution(Vz)were significantly different from those in the solution group.The distribution of mouse tissues showed that the drug concentrations in the liver and lung tissues of the microsphere preparation group were higher than those in the injection group,and the drug concentrations in the lung and liver tissues were more distributed.Conclusion:The targeted drug delivery system changed the pharmacokinetic behavior and tissue distribution of euphorbia sterol,slowed down plasma elimination,prolonged the half-life,and improved the targeting of drugs in lung and liver tissues and the magnetic targeting effect of lungs.展开更多
A novel parameter identification method for magnetic levitation bearing rotor systems is proposed,based on the modulation function method.The fundamental principle of the modulation function method for parameter ident...A novel parameter identification method for magnetic levitation bearing rotor systems is proposed,based on the modulation function method.The fundamental principle of the modulation function method for parameter identification is derived on the basis of the characteristics of the modulation function.The transformation of the differential equation model of a continuous system into a general algebraic equation model is effectively achieved,thereby avoiding the influence of errors introduced by the initial value and differential derivation of the system.Modulation function method parameter identification models have been established for single-degree-of-freedom and multi-degree-of-freedom magnetic levitation bearing rotor systems.The influence of different parameters of Hartley modulation function on the accuracy of system parameter identification has been investigated,thus providing a basis for the design of Hartley modulation function parameters.Simulation and experimental results demonstrate that the modulation function method can effectively identify system parameters despite the presence of system noise.展开更多
文摘Single-phase diluted magnetic systems Zn1-xFexO have been prepared by chemical route. Structural and spectroscopic （UV-Vis and Mossbauer） studies indicate the incorporation of Fe^3＋ ions in the lattice sites. The UV-Vis results point to a systematic increase in the band gap with increasing Fe doping. The room temperature magnetization of Zni-xFexO indicates a paramagnetic behavior which is in accordance with the Mossbauer results, illustrating quadrupolar doublet. At low temperature, the zero-field-cooled （ZFC） magnetization shows a cusp and this temperature increases systematically with decreasing particle size. The weak exchange bias effect manifested by a M-H loop shift is observed for x = 0.03. This shift is accompanied by the enhancement of coercivity. The dc magnetization results suggest the coexis tence of ferromagnetic and antiferromagnetic exchange interactions for low doping of Fe, i.e., for x = 0.03.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB927402)the National Natural Science Foundation of China(GrantNos.11074145 and 61275028)
文摘In this paper, we present a comprehensive investigation of the effects of the transverse correlation function （TCF） on the thermodynamic properties of Heisenberg antiferromagnetic （AFM） and ferromagnetic （FM） systems with cubic lattices. The TCF of an FM system is positive and increases with temperature, while that of an AFM system is negative and decreases with temperature. The TCF lowers internal energy, entropy and specific heat. It always raises the free energy of an FM system but raises that of an AFM system only above a specific temperature when the spin quantum number is S 〉 1. Comparisons between the effects of the TCFs on the FM and AFM systems are made where possible.
基金Sponsored by Postdoctoral Fund of Heilongjiang Province (Grant NoLRB05 -002)
文摘Polarized magnetic system has a series of features, such as small volume, light weight, low power consumption, high sensitivity, quick movement and so on, widely used in the products of the military aerospace electromagnetic relay. The typical polarized magnetic system has mainly four structures and its simplified equivalent magnetic circuits model is the base of the design of the electromagnetic relay with permanent magnet. In the past, the analysis method that people used was difficult to build the unified mathematical models, which divided the work gap magnetic flux into "permanent magnet flux" and "electromagnetic flux". Based on the analysis method of the work gap magnetic voltage, this paper founds the unified mathematical model of the polarized magnetic system and divides the attractive torque into permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula. It analyses the influence of permanent magnet sizes on permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula and the conclusions can direct the design of aerospace electromagnetic relay with permanent magnet.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10574048 and 20490210
文摘The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the single-ion anisotropy are included, our results indicate that there are compensation points at finite temperatures. When the next-nearest-neighbor interaction exceeds a minimum value that depends on the other parameters in the Hamiltonian, the compensation point disappears. The next-nearest-neighbor interaction has the effect of changing the compensation temperature.
基金support of National Natural Science Foundation of China(Nos.51177021,51207028)
文摘Modeling of permanent magnet（PM） is very important in the process of electromagnetic system calculation of aerospace electromagnetic relay（AEMR）. In traditional analytical calculation, PM is often equivalent to a lumped parameter model of one magnetic resistance and one magnetic potential, but great error is often caused for the inner differences of PM; based on the conception of flux tube, a type of 2D magnetic equivalent circuit framework of permanent magnet model（2D MECF） is established; the element is defined, the relationship between elements is deduced, and solution procedure as well as verification condition of this model is given; by a case study of the electromagnetic system of a certain type of AEMR, the electromagnetic system calculation model is established based on 2D MECF and the attractive force at different rotation angles is calculated; the proposed method is compared with the traditional lumped parameter model and finite element method（FEM）; for some types of electromagnetic systems with symmetrical structure, 2D MECF proves to be of acceptable accuracy and high calculation speed which fit the requirement of robust design for AEMR.
文摘A new design of stato magnetic System is Proposed for 3-phase & 12-pole HB stepper, and it features bet-ter distribution of magntic lield to incare Pullou tope and bopmve Operaonal stability of moor and minimummutual inductance between phase windimp to make design of control circuit easier, and application proved it is as good as expected.
文摘The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z|J|,DB/z|J|) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z|J| and DB/z|J|. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.
文摘The mixed spin-3/2 and spin-2 Ising ferrimagnetic system with different single-ion anisotropies in the absence of an external magnetic field is studied within the mean-field theory based on Bogoliubov inequality for the Gibbs free energy. Second-order critical lines are obtained in the temperature-anisotropy plane. Tricritical line separating second-order and first-order lines is found. Finally, the existence and dependence of a compensation points on single-ion anisotropies is also investigated for the system. As a result, this mixed-spin model exhibits one, two or three compensation temperature depending on the values of the anisotropies.
基金supported by the National Natural Science Foundation of China(Grant Nos.12450004,12274288,12334008,and 12174441)the National Key R&D Program of China(Grant No.2023YFA1406500)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301900)。
文摘Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.With accurate descriptions of the ground states and low-energy excitations of(quasi-)one-dimensional(1D)quantum spin models,significant progress has been made in studying quantum criticality and related emergent physics.In this review,we provide a short survey on some recent developments in this field.We start by discussing critical thermodynamics and dynamics of transverse-field Ising chain,highlighting novel quantum integrability and many-body excitations upon relevant perturbations.Dynamical properties of the excitations are further discussed,along with their experimental verification.Along the line of integrability,we further discuss the Heisenberg-Ising chain,introducing the string magnetic state.Among them,non-trivial string solutions which go beyond conventional field theory,have also been observed in experiments.Apart from the critical phenomena associated with the standard Ginzburg-Landau paradigm,we introduce the deconfined quantum criticality,which arises as a consequence of a continuous phase transition between two ordered states.Such a transition goes beyond the description of the Ginzburg-Landau paradigm and is characterized by the emergence of fractionalized spin excitations and enhanced continuous symmetry at the quantum critical point.Finally,we conclude by highlighting potential novel critical phenomena and emergent physics and their realizations in quasi-1D quantum magnetic systems.
基金financially supported by the National Natural Science Foundation of China(42250102,42250101)the Macao Foundation and Macao Science and Technology Development Fund(0001/2019/A1)the Pre-research Project on Civil Aerospace Technologies funded by China National Space Administration(D020303)。
文摘This study presents preliminary results of tidal-induced magnetic field signals extracted from 9 months of data collected by the Macao Science Satellite-1(MSS-1) from November 2023 to July 2024. Tidal signals were isolated using sequential modeling techniques by subtracting non-tidal field model predictions from observed magnetic data. The extracted MSS-1 results show strong agreement with those from the Swarm and CryoSat satellites. MSS-1 effectively captures key large-scale tidal-induced magnetic anomalies, mainly due to its unique 41-degree low-inclination orbit, which provides wide coverage of local times. This finding underscores the strong potential of MSS-1 to recover high-resolution global tidal magnetic field models as more MSS-1 data become available.
基金the National Natural Science Foundation of China(Nos.52275038 and 61803347)the Shanxi Province Science Foundation for Excellent Youth(No.202203021224007)+1 种基金the Key Research and Development Plan of Shanxi Province(No.201903D321164)the Opening Foundation of Shanxi Key Laboratory of Advanced Manufacturing Technology(No.XJZZ202101)。
文摘Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embedded in the capsule accurately in advance,which can cause inconvenience to practical application.To solve this problem,this paper proposes a magnetic tracking system with the capability of measuring themagnetic moment of the PM automatically.The system is constructed based on a 4×4 magnetic sensor array,whose sensing data is analyzed to determine the magnetic moment by referring to a magnetic dipole model.Withthe determined magnetic moment,a method of fusing the linear calculation and Levenberg-Marquardt algorithmsis proposed to determine the 3D position and 2D attitude of the PM.The experiments verified that the proposedsystem can achieve localization errors of 0.48 mm,0.42 mm,and 0.83 mm and orientation errors of 0.66◦,0.64◦,and 0.87◦for a PM(∅10 mm×10 mm)at vertical heights of 5 cm,10 cm,and 15 cm from the magnetic sensorarray,respectively.
基金supported in part by the National Natural Science Foundation of China(62225306,U2141235,52188102).
文摘Dear Editor,Active magnetic bearings(AMBs)are of considerable interest and significance in smart manufacturing due to their zero-friction and adaptivity to noncontact rotor rotations.This paper proposes an active levitation control algorithm based on adaptive sliding mode control(ASMC)equipped with linear extended state observer(LESO).Sufficient conditions are derived to guarantee the asymptotical stability of the associated closed-loop system.Experiments are conducted on a real AMB-rotor platform to demonstrate the effectiveness and superiority of the proposed algorithm.
文摘BACKGROUND Trichotillomania is a challenging to treat psychiatric disorder,with limited evidence for pharmacotherapy.Treatment typically involves medication,cognitive behavioral therapy,and behavioral interventions.Recently,transcranial magnetic stimulation(TMS)has emerged as a potential treatment strategy.AIM To assess the role of TMS in treating trichotillomania.METHODS A systematic search using specific terms was done in PubMed and Scopus databases for articles published until May 17,2024,related to trichotillomania and TMS.The search included randomized controlled trials,open-label studies,case series,case reports,and retrospective chart reviews,following the Preferred Items for Systematic Reviews and Meta-Analysis guideline.RESULTS We identified 32 articles(6 in PubMed and 26 in Scopus).After removing duplicates and articles that did not meet the selection criteria,we conducted a final analysis of four articles.These included one retrospective study,two case series,and one case study,with a total of 22 patients diagnosed with trichotillomania enrolled across all four studies.The brain areas targeted were the supplementary motor area(SMA),pre-SMA,and left dorsolateral prefrontal cortex.The studies reported an improvement in the severity of symptoms of trichotillomania in the majority of patients with negligible side effects.Nevertheless,it is important to note that the existing studies are mostly of low to moderate quality.CONCLUSION Early evidence suggests repetitive TMS and accelerated continuous theta burst stimulation can help treat trichotillomania adjunctively to other treatments.
基金supported by the National Natural Science Foundation of China(62122064,62331021,62371410)the Natural Science Foundation of Fujian Province of China(2023J02005 and 2021J011184)+1 种基金the President Fund of Xiamen University(20720220063)the Nanqiang Outstanding Talents Program of Xiamen University.
文摘Magnetic resonance imaging(MRI)plays an important role in medical diagnosis,generating petabytes of image data annually in large hospitals.This voluminous data stream requires a significant amount of network bandwidth and extensive storage infrastructure.Additionally,local data processing demands substantial manpower and hardware investments.Data isolation across different healthcare institutions hinders crossinstitutional collaboration in clinics and research.In this work,we anticipate an innovative MRI system and its four generations that integrate emerging distributed cloud computing,6G bandwidth,edge computing,federated learning,and blockchain technology.This system is called Cloud-MRI,aiming at solving the problems of MRI data storage security,transmission speed,artificial intelligence(AI)algorithm maintenance,hardware upgrading,and collaborative work.The workflow commences with the transformation of k-space raw data into the standardized Imaging Society for Magnetic Resonance in Medicine Raw Data(ISMRMRD)format.Then,the data are uploaded to the cloud or edge nodes for fast image reconstruction,neural network training,and automatic analysis.Then,the outcomes are seamlessly transmitted to clinics or research institutes for diagnosis and other services.The Cloud-MRI system will save the raw imaging data,reduce the risk of data loss,facilitate inter-institutional medical collaboration,and finally improve diagnostic accuracy and work efficiency.
基金supported by the National Science Foundation of China(Grant No.52293423 and Grant No.52277031).
文摘After the fabrication of magnetic resonance superconducting magnets,the magnetic field inhomogeneity needs to be accurately measured for subsequent shimming.However,conventional measurement methods are susceptible to magnetic fields,have poor compatibility,and are difficult to adapt to various types of magnets.This paper proposes a new field measuring system based on a three-axis movable platform.The system utilizes non-magnetic materials and an innovative hand-wheel lifting design that can be adapted to various aperture magnets,thus obviating the necessity for electrically driven equipment and addressing safety concerns in strong magnetic fields.In addition,the measurement system offers high accuracy up to 1 mm and a wide measurable range.The fields of 3 T and 7 T magnets were mapped using the designed system with diameter of spherical volume(DSV)of 160 mm and 130 mm,respectively.Experimental results demonstrate that the magnetic field measurement system has strong compatibility and can accurately map the magnetic field at arbitrary positions,which is critical for shimming studies.
基金funded by the Deanship of Scientific Research and Libraries,Princess Nourah bint Abdulrahman University,through the Program of Research Project Funding after Publication,grant No.(RPFAP-88-1445).
文摘Cooling system design applicable to more than one photovoltaic(PV)unit may be challenging due to the arrangement and geometry of the modules.Different cooling techniques are provided in this study to regulate the temperature of conductive panels that are arranged perpendicular to each other.The model uses two vented cavity systems and one L-shaped channel with ternary nanofluid enhanced non-uniform magnetic field.Their cooling performances and comparative results between different systems are provided.The finite element method is used to conduct a numerical analysis for a range of values of the following:the strength of themagnetic field(Hartmann number(Ha)between 0 and 50),the inclination of the magnetic field(γbetween 0 and 90),and the loading of nanoparticles in the base fluid(ϕbetween 0 and 0.03),taking into account both uniformand non-uniformmagnetic fields.For the L-shaped channel and vented cavities,vortex size is controlled by imposing magnetic field and adjusting its strength.Whether uniform or non-uniform magnetic field is applied affects the cooling performances for different cooling configurations.Temperature drops of the horizontal panel with different magnetic field strengths by using channel cooling,vented cavity-1 and vented cavity-2 systems for uniformmagnetic are 11℃,21.5℃,and 3℃when the reference case of Ha=0 is considered for the same cooling systems.However,they become 9.5℃,13.5℃,and 12.5℃when nonuniform magnetic field is used.In the presence of uniform magnetic field effects and changing its magnitude,the use of cooling channel in vented cavity-1 and vented cavity-2 systems results in temperature drops of 4℃,10.8℃,and 3.8℃for vertical panels.On the other hand,when non-uniform magnetic field effects are present,they become 0.5℃,2.1℃,and 9℃.For L-channel cooling,the average Nu for the horizontal panel is more affected byγ,andNu rises asγrises.With increasing nanoparticle loading of ternary nanofluid,the average panel surface temperature shows a linear drop.For the horizontal panel,the temperature declines for nanofluid at the highest loading are 4℃,10℃,and 12℃as compared to using only base fluid.The values of 5℃,7℃,and 11℃are obtained for the vertical panel.Different cooling systems’performance is estimated using artificial neural networks.The method captures the combined impact of applying non-uniformmagnetic field and nanofluid together on the cooling performancewhile accounting for varied cooling strategies for both panels.
文摘[Objectives]To evaluate the effects of repetitive transcranial magnetic stimulation(rTMS)on neurophysiological outcomes in patients with acute stroke.[Methods]A systematic literature search was conducted across PubMed,EMBASE,Web of Science,the Cochrane Central Register of Controlled Trials(CENTRAL),and CINAHL databases up to March 1,2025.Randomized controlled trials(RCTs)and clinical controlled trials(CCTs)involving adult patients(≥18 years)with acute ischemic stroke(within 2 weeks of onset)who received rTMS intervention were included.Data on motor evoked potential(MEP)amplitude,resting motor threshold(RMT),and central motor conduction time(CMCT)were extracted.The quality of the studies was assessed using the Cochrane risk of bias tool.Statistical analyses were performed using Stata 18.0,with standardized mean differences(SMDs)and 95%confidence intervals(CIs)calculated.Heterogeneity was evaluated using the I^(2)statistic.[Results]Eight studies involving 932 identified records met the inclusion criteria.Meta-analysis revealed that rTMS significantly increased MEP amplitude(Hedges'g=0.77,95%CI:0.52-1.02,P<0.01)and reduced RMT(Hedges g=-1.13,95%CI:-1.63 to-0.62,P<0.01)in the lesioned hemisphere,indicating enhanced corticospinal excitability.No significant effects were observed on MEP amplitude or RMT in the unaffected hemisphere.Additionally,rTMS did not significantly alter CMCT in either hemisphere.Heterogeneity was low to moderate for most outcomes,and no significant publication bias was detected.[Conclusions]rTMS is a safe and effective intervention for improving corticospinal excitability and motor recovery in patients with acute stroke.Both high-frequency stimulation of the ipsilesional hemisphere and low-frequency stimulation of the contralesional hemisphere have demonstrated beneficial effects,supporting the interhemispheric inhibition model.Future large-scale,multi-center RCTs are needed to optimize rTMS parameters and establish standardized treatment protocols for acute stroke rehabilitation.
文摘Objective:Although bariatric surgeries are widely performed around the world,patients frequently experience the recurrence of pre-existing gastroesophageal reflux disease(GERD)symptoms or develop new symptoms,some of which are resistant to medical treatment.This study investigates the effect and outcome of magnetic sphincter augmentation(MSA),a minimally invasive treatment for GERD,in this population.Methods:A thorough search of the PubMed,Cochrane,Scopus,Web of Science,and Google Scholar databases from inception until June 6,2024 was performed to retrieve relevant studies that evaluated the effects of MSA on the GERD health-related quality of life(GERD-HRQL)score and the reduction in proton pump inhibitor(PPI)use in patients who underwent bariatric surgery.The“meta”package in RStudio version 2023.12.0 t 369 was used.Results:A total of eight studies were included in the systematic review and seven studies were included in the meta-analysis.MSA significantly reduced the GERD-HRQL score(MD?27.55[95%CI:30.99 to24.11],p<0.01)and PPI use(RR?0.23[95%CI:0.16 to 0.33],p<0.01).Conclusion:MSA is a viable treatment option for patients with GERD symptoms who undergo bariatric surgery.This approach showed promising results in terms of reducing the GERD-HRQL score and reducing the use of PPI.
基金sponsored by the Fundamental Research Funds forthe Central Universities(No.2024-JYB-JBZD-047)High Level Key Discipline Construction of Traditional Chinese Medicine(zyyzdxk-2023272).
文摘Background:Building upon our previous work that developed a folate receptor-mediated,euphaorbia factor L1-loaded PLGA microsphere system integrating active and magnetic targeting for theranostics,further investigation into its in vivo pharmacokinetics and tissue distribution is warranted despite its demonstrated biocompatibility and safety.Methods:A UPLC-MS/MS method was established to determine the concentration of euphorbia sterol in rat plasma and mouse tissue homogenates,healthy male SD rats and KM mice were administered in groups,drug concentrations at different time points were determined,pharmacokinetic parameters were analyzed by DAS software,and data were processed by SAS software.Results:The proposed method met the requirements of biological sample detection.The plasma pharmacokinetics of rats showed that the drug concentration in the microsphere group was lower than that in the injection group,and the parameters such as mean residence time(MRT(0–t)),half-life(T1/2z)and apparent volume of distribution(Vz)were significantly different from those in the solution group.The distribution of mouse tissues showed that the drug concentrations in the liver and lung tissues of the microsphere preparation group were higher than those in the injection group,and the drug concentrations in the lung and liver tissues were more distributed.Conclusion:The targeted drug delivery system changed the pharmacokinetic behavior and tissue distribution of euphorbia sterol,slowed down plasma elimination,prolonged the half-life,and improved the targeting of drugs in lung and liver tissues and the magnetic targeting effect of lungs.
基金supported by the National Science and Technology Major Project(Grant No.J2019-Ⅳ-0003-0070).
文摘A novel parameter identification method for magnetic levitation bearing rotor systems is proposed,based on the modulation function method.The fundamental principle of the modulation function method for parameter identification is derived on the basis of the characteristics of the modulation function.The transformation of the differential equation model of a continuous system into a general algebraic equation model is effectively achieved,thereby avoiding the influence of errors introduced by the initial value and differential derivation of the system.Modulation function method parameter identification models have been established for single-degree-of-freedom and multi-degree-of-freedom magnetic levitation bearing rotor systems.The influence of different parameters of Hartley modulation function on the accuracy of system parameter identification has been investigated,thus providing a basis for the design of Hartley modulation function parameters.Simulation and experimental results demonstrate that the modulation function method can effectively identify system parameters despite the presence of system noise.
