As an innovative,low-power consuming,and low-stiffness suspension approach,the diamagnetic levitation technique has attracted considerable interest because of its potential applicability in miniaturized mechanical sys...As an innovative,low-power consuming,and low-stiffness suspension approach,the diamagnetic levitation technique has attracted considerable interest because of its potential applicability in miniaturized mechanical systems.The foundation of a diamagnetic levitation system is mathematical modeling,which is essential for operating performance optimization and stability prediction.However,few studies on systematic mathematical modeling have been reported.In this study,a systematic mathematical model for a disc-shaped diamagnetically levitated rotor on a permanent magnet array is proposed.Based on the proposed model,the magnetic field distribution characteristics,diamagnetic levitation force characteristics(i.e.,levitation height and stiffness),and optimized theoretical conditions for realizing stable levitation are determined.Experiments are conducted to verify the feasibility of the proposed mathematical model.Theoretical predictions and experimental results indicate that increasing the levitation height enlarges the stable region.Moreover,with a further increase in the rotor radius,the stable regions of the rotor gradually diminish and even vanish.Thus,when the levitation height is fixed,a moderate rotor radius permits stable levitation.This study proposes a mathematical modeling method for a diamagnetic levitation system that has potential applications in miniaturized mechanical systems.展开更多
Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound （US） and magnetic resonance （MR） dual imaging, the controlled therapeutic delivery, as well as theran...Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound （US） and magnetic resonance （MR） dual imaging, the controlled therapeutic delivery, as well as theranostic multifunctions are all introduced based on recent research results. Some on-going research is also discussed.展开更多
Intertech-Pira has announced that its conference 'China Magnetics 2006' will be held on September 19-21, 2006 at the Sofitel Shanghai Hotel in Shanghai, China. This event is expected to attract over 150 attend...Intertech-Pira has announced that its conference 'China Magnetics 2006' will be held on September 19-21, 2006 at the Sofitel Shanghai Hotel in Shanghai, China. This event is expected to attract over 150 attendees.展开更多
The magnetic circuit of a kind of permanent magnetic sucker attached to the tracks of a wall climbing robot was researched. The formula of the attractive force of sucker to a wall was derived and the relationship betw...The magnetic circuit of a kind of permanent magnetic sucker attached to the tracks of a wall climbing robot was researched. The formula of the attractive force of sucker to a wall was derived and the relationship between the force and the air gaps was analyzed. Furthermore the effect of the parameters of the magnetic sucker on the sucker’s performance was discussed. The experiments show that proper selections of the sucker’s structural parameters can provide sufficient attractive force so as to make the wall climbing robot move safely on the steel wall surface.展开更多
The computational study of the combined effects of radiation and hydro- magnetics on the natural convection flow of a viscous, incompressible, and electrically conducting fluid past a magnetized permeable vertical pla...The computational study of the combined effects of radiation and hydro- magnetics on the natural convection flow of a viscous, incompressible, and electrically conducting fluid past a magnetized permeable vertical plate is presented. The governing non-similar equations are numerically solved by using a finite difference method for all values of the suction parameter and the asymptotic solution for small and large values of ~. The effects of varying the Prandtl number Pr, the magnetic Prandtl number Prm, the magnetic force parameter S, the radiation parameter Rd, and the surface temperature Ow on the coefficients of the skin friction, the rate of heat transfer, and the current density are shown graphically and in tables. An attempt is made to examine the effects of the above mentioned physical parameters on the velocity profile, the temperature distribution, and the transverse component of the magnetic field.展开更多
Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently d...Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently discovered diluted magnetic semiconductor(Ba,K)(Zn,Mn)_2 As_2, which has the record of reliable Curie temperature of 230 K due to independent charge and spin doping. Sb and P are substituted into As-site to produce negative and positive chemical pressures, respectively.X-ray diffraction results demonstrate the successful chemical solution of dopants. Magnetic properties of both K-underdoped and K-optimal-doped samples are effectively tuned by Sb-and P-doping. The Hall effect measurements do not show decrease in carrier concentrations upon Sb-and P-doping. Impressively, magnetoresistance is significantly improved from7% to 27% by only 10% P-doping, successfully extending potential application of(Ba,K)(Zn,Mn)_2 As_2.展开更多
The Schr?dinger differential equation is what we usually solve for the microscopic particles in non-relativistic quantum mechanics. Niels Bohr suggested the power two of the (usually) complex answer shows the probabil...The Schr?dinger differential equation is what we usually solve for the microscopic particles in non-relativistic quantum mechanics. Niels Bohr suggested the power two of the (usually) complex answer shows the probability of the particle’s existence at a point of space. Also, the time dependence of Schrodinger wave equation is one whereas for light in electromagnetism is two. In this paper, we show a solution for both problems. We derive a Wave Equation for the energy of every system. This electromagnetic wave equation is shown to convert to those classical (i.e. the Schrodinger) and special relativistic (i.e. Klein-Gordon) quantum mechanical equations. Also, accordingly there definitely is a physical meaning to answer to this wave equation. And therefore, switching the probabilistic interpretation of quantum mechanics to a deterministic one as (Albert) Einstein demanded.展开更多
The geology of Magaoni area is associated with the presence of heavy minerals [1]. Magaoni’s neighbours Maumba and Nguluku where ilmenite was discovered by Tiomin Resource Inc. in 1996, using drilling and chemical an...The geology of Magaoni area is associated with the presence of heavy minerals [1]. Magaoni’s neighbours Maumba and Nguluku where ilmenite was discovered by Tiomin Resource Inc. in 1996, using drilling and chemical analysis [2]. Ilmenite mineral is known to be magnetically weak, but provides observable magnetic response [3]. In this study, ground magnetic survey method was carried out to map magnetic anomalies of established stations, associated with ilmenite bearing formations. The magnetic contour map plotted showed weak and shallow magnetic signatures spread throughout the study area. 2D Euler deconvolution solutions revealed presence of magnetised formations from near surface to a maximum depth of about 450 m at some points. The weak magnetic formations of near surface indicated presence of ilmenite. Energy dispersive X-ray spectroscopy was done on soil samples collected randomly from the study area to determine the percentage of iron and titanium oxides. The results showed elevated values of titanium dioxide, ranging from 1.5% to 13% which is way above the global average of about 0.7% [4]. The percentage of iron oxide was low, ranging from 1.5% to 4%, this being the reason for weak magnetisation of the study area.展开更多
Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport prope...Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport properties is crucial for TE technology,in which magnetism has provided a new degree of freedom in decoupling electron and phonon transports.This paper provides a comprehensive overview of recent advancements in magnetics-induced enhancement for both longitudinal and transverse TE systems.Initially,two key optimization strategies for longitudinal TE power generation are explored:enhancing non-magnetic TE performance in intrinsic magnetic materials and optimizing magnetic TE performance by utilizing extrinsic magnetism-induced effects.Following this,the mechanism by which external magnetic fields enhance transverse TE conversion is explained in detail.Moreover,we discuss in depth how magnetism influences the electron and phonon transports from a physical perspective.Finally,the promising applications of magnetics-induced TE technology in both power generation and solid-state cooling are discussed,with some key challenges being proposed.展开更多
经颅磁刺激(transcranial magnetic stimulation, TMS)是一种神经调制方法,临床中凭借医生经验手动确定TMS线圈摆放位姿,导致线圈摆放位置和姿态不准确且重复定位精度差。针对上述问题,提出一种TMS线圈机器人辅助定位系统,使用RGB相机...经颅磁刺激(transcranial magnetic stimulation, TMS)是一种神经调制方法,临床中凭借医生经验手动确定TMS线圈摆放位姿,导致线圈摆放位置和姿态不准确且重复定位精度差。针对上述问题,提出一种TMS线圈机器人辅助定位系统,使用RGB相机替代导航系统中双目红外相机,采用一种基于神经网络的无标志物TMS线圈机器人辅助定位方法。搭建神经网络实现相机空间线圈姿态到操作臂空间关节角度的映射,并通过仿真数据训练验证了该神经网络架构适用于TMS线圈位姿摆放问题。随后,通过实验验证了该方法的可行性,同时表明训练的神经网络针对TMS线圈定位任务具有良好的泛化能力。最后,在笛卡儿空间的位姿验证结果显示TMS线圈三维位置平均误差为2.16 mm,总体姿态误差为0.055 rad,使用RGB相机的TMS线圈机器人辅助定位系统在精度上达到了与其他使用双目红外相机的科研或商用系统相同的水平,满足TMS临床治疗要求,具备临床应用的可行性。展开更多
The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific ...The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific configuration of applied magnetics fields and current and can persist up to 20 K,much higher than the Ne'el temperature(T_(N)≈1.9 K).Experiments and first-principles calculations suggest that the observed large negative MR is derived from a magnetic field that reconstructs the band structure and induces a Weyl point,which changes the carrier concentration.展开更多
Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significan...Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.展开更多
Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have ...Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have on our aging population.Posture and gait control does not happen automatically,as previously believed,but rather requires continuous involvement of central nervous mechanisms.To effectively exert control over the body,the brain must integrate multiple streams of sensory information,including visual,vestibular,and somatosensory signals.The mechanisms which underpin the integration of these multisensory signals are the principal topic of the present work.Existing multisensory integration theories focus on how failure of cognitive processes thought to be involved in multisensory integration leads to falls in older adults.Insufficient emphasis,however,has been placed on specific contributions of individual sensory modalities to multisensory integration processes and cross-modal interactions that occur between the sensory modalities in relation to gait and balance.In the present work,we review the contributions of somatosensory,visual,and vestibular modalities,along with their multisensory intersections to gait and balance in older adults and patients with Parkinson’s disease.We also review evidence of vestibular contributions to multisensory temporal binding windows,previously shown to be highly pertinent to fall risk in older adults.Lastly,we relate multisensory vestibular mechanisms to potential neural substrates,both at the level of neurobiology(concerning positron emission tomography imaging)and at the level of electrophysiology(concerning electroencephalography).We hope that this integrative review,drawing influence across multiple subdisciplines of neuroscience,paves the way for novel research directions and therapeutic neuromodulatory approaches,to improve the lives of older adults and patients with neurodegenerative diseases.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
With the continuous development of power supplies toward miniaturization,light weights,and high levels of integration,research on high-frequency resonant conversion based on planar magnetics is becoming extensive.Comb...With the continuous development of power supplies toward miniaturization,light weights,and high levels of integration,research on high-frequency resonant conversion based on planar magnetics is becoming extensive.Combining the soft-switching characteristics of resonant converters with those of wide bandgap devices,the switching frequency can be increase to the MHz range,and the power density of the entire system can be improved considerably.However,higher switching frequencies impose new requirements for the structural design,loss distribution,and common mode(CM)noise suppression of passive magnetic components.Herein,a thorough survey of the-state-of-the-art of planar magnetics in high-frequency resonant converters is conducted.Printed circuit board winding-based planar magnetics,magnetic integration,and power-loss optimization strategies are summarized in detail.Suppression methods for CM noise in high-frequency planar magnetics are also clarified and discussed.An insight view into the future development of planar magnetics for high-frequency resonant converters is presented.展开更多
The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic...The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.展开更多
This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar...This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar-orbiting(Swarm)and low-inclination(MSS-1)satellites in geomagnetic modelling and monitoring large-scale magnetospheric contributions.Data from close encounters between MSS-1 and Swarm(intersatellite distance<100 km)confirm the excellent data quality of the two satellite missions(<1 nT median difference in scalar intensity F)and allow for data calibration and validation and investigations of in-situ ionospheric currents.The reason for a small but consistent difference(F as measured by MSS-1 is 0.5 to 1.0 nT larger than that measured by Swarm)is unknown.Combining MSS-1’s low-inclination data with Swarm’s near-polar observations significantly enhances the spatial-temporal resolution of Earth’s magnetic field models,allowing for new opportunities for studying both rapid core field variations at low latitudes and the local-time dependence of large-scale magnetospheric current systems.A joint analysis of magnetic data from six satellites during the May 2024 geomagnetic storm reveals a clear dawn-dusk asymmetry,with equatorial magnetic disturbances during dusk being approximately 150 nT more negative than during dawn.展开更多
The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic ...The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic frameworks(MOFs)are ideal self-sacrificing templates for the construction of carbon-based EMW absorbers.In this work,bimetallic FeMn-MOF-derived MnFe_(2)O_(4)/C/graphene composites were fabricated via a two-step route of solvothermal reaction and the following pyrolysis treatment.The results re-veal the evolution of the microscopic morphology of carbon skeletons from loofah-like to octahedral and then to polyhedron and pomegran-ate after the adjustment of the Fe^(3+)to Mn^(2+)molar ratio.Furthermore,at the Fe^(3+)to Mn^(2+)molar ratio of 2:1,the obtained MnFe_(2)O_(4)/C/graphene composite exhibited the highest EMW absorption capacity.Specifically,a minimum reflection loss of-72.7 dB and a max-imum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of 10wt%.In addition,the possible EMW absorp-tion mechanism of MnFe_(2)O_(4)/C/graphene composites was proposed.Therefore,the results of this work will contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.展开更多
基金Supported by National Natural Science Foundation of China (Grant No.52275537)Nanjing Major Scientific and Technological Project of China (Grant No.202209011)。
文摘As an innovative,low-power consuming,and low-stiffness suspension approach,the diamagnetic levitation technique has attracted considerable interest because of its potential applicability in miniaturized mechanical systems.The foundation of a diamagnetic levitation system is mathematical modeling,which is essential for operating performance optimization and stability prediction.However,few studies on systematic mathematical modeling have been reported.In this study,a systematic mathematical model for a disc-shaped diamagnetically levitated rotor on a permanent magnet array is proposed.Based on the proposed model,the magnetic field distribution characteristics,diamagnetic levitation force characteristics(i.e.,levitation height and stiffness),and optimized theoretical conditions for realizing stable levitation are determined.Experiments are conducted to verify the feasibility of the proposed mathematical model.Theoretical predictions and experimental results indicate that increasing the levitation height enlarges the stable region.Moreover,with a further increase in the rotor radius,the stable regions of the rotor gradually diminish and even vanish.Thus,when the levitation height is fixed,a moderate rotor radius permits stable levitation.This study proposes a mathematical modeling method for a diamagnetic levitation system that has potential applications in miniaturized mechanical systems.
基金Project supported by the National Basic Research Program of China (Grant Nos.2011CB933503 and 2013CB733804)the National Natural Science Foundation of China (Grant No.31000453)the Fundamental Research Funds for Central Universities (Grant No.2013CB733804)
文摘Generation of magnetic micrbubbles and their basic magnetic and acoustic mechanism are reviewed. The ultrasound （US） and magnetic resonance （MR） dual imaging, the controlled therapeutic delivery, as well as theranostic multifunctions are all introduced based on recent research results. Some on-going research is also discussed.
文摘Intertech-Pira has announced that its conference 'China Magnetics 2006' will be held on September 19-21, 2006 at the Sofitel Shanghai Hotel in Shanghai, China. This event is expected to attract over 150 attendees.
基金Doctoral Fund of the National EducationCommittee
文摘The magnetic circuit of a kind of permanent magnetic sucker attached to the tracks of a wall climbing robot was researched. The formula of the attractive force of sucker to a wall was derived and the relationship between the force and the air gaps was analyzed. Furthermore the effect of the parameters of the magnetic sucker on the sucker’s performance was discussed. The experiments show that proper selections of the sucker’s structural parameters can provide sufficient attractive force so as to make the wall climbing robot move safely on the steel wall surface.
文摘The computational study of the combined effects of radiation and hydro- magnetics on the natural convection flow of a viscous, incompressible, and electrically conducting fluid past a magnetized permeable vertical plate is presented. The governing non-similar equations are numerically solved by using a finite difference method for all values of the suction parameter and the asymptotic solution for small and large values of ~. The effects of varying the Prandtl number Pr, the magnetic Prandtl number Prm, the magnetic force parameter S, the radiation parameter Rd, and the surface temperature Ow on the coefficients of the skin friction, the rate of heat transfer, and the current density are shown graphically and in tables. An attempt is made to examine the effects of the above mentioned physical parameters on the velocity profile, the temperature distribution, and the transverse component of the magnetic field.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0405703)the Ministry of Science and Technology of China(Grant Nos.2018YFA03057001 and 2015CB921000)the National Natural Science Foundation of China through the Research Projects(Grant Nos.11534016and 61504166)
文摘Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently discovered diluted magnetic semiconductor(Ba,K)(Zn,Mn)_2 As_2, which has the record of reliable Curie temperature of 230 K due to independent charge and spin doping. Sb and P are substituted into As-site to produce negative and positive chemical pressures, respectively.X-ray diffraction results demonstrate the successful chemical solution of dopants. Magnetic properties of both K-underdoped and K-optimal-doped samples are effectively tuned by Sb-and P-doping. The Hall effect measurements do not show decrease in carrier concentrations upon Sb-and P-doping. Impressively, magnetoresistance is significantly improved from7% to 27% by only 10% P-doping, successfully extending potential application of(Ba,K)(Zn,Mn)_2 As_2.
文摘The Schr?dinger differential equation is what we usually solve for the microscopic particles in non-relativistic quantum mechanics. Niels Bohr suggested the power two of the (usually) complex answer shows the probability of the particle’s existence at a point of space. Also, the time dependence of Schrodinger wave equation is one whereas for light in electromagnetism is two. In this paper, we show a solution for both problems. We derive a Wave Equation for the energy of every system. This electromagnetic wave equation is shown to convert to those classical (i.e. the Schrodinger) and special relativistic (i.e. Klein-Gordon) quantum mechanical equations. Also, accordingly there definitely is a physical meaning to answer to this wave equation. And therefore, switching the probabilistic interpretation of quantum mechanics to a deterministic one as (Albert) Einstein demanded.
文摘The geology of Magaoni area is associated with the presence of heavy minerals [1]. Magaoni’s neighbours Maumba and Nguluku where ilmenite was discovered by Tiomin Resource Inc. in 1996, using drilling and chemical analysis [2]. Ilmenite mineral is known to be magnetically weak, but provides observable magnetic response [3]. In this study, ground magnetic survey method was carried out to map magnetic anomalies of established stations, associated with ilmenite bearing formations. The magnetic contour map plotted showed weak and shallow magnetic signatures spread throughout the study area. 2D Euler deconvolution solutions revealed presence of magnetised formations from near surface to a maximum depth of about 450 m at some points. The weak magnetic formations of near surface indicated presence of ilmenite. Energy dispersive X-ray spectroscopy was done on soil samples collected randomly from the study area to determine the percentage of iron and titanium oxides. The results showed elevated values of titanium dioxide, ranging from 1.5% to 13% which is way above the global average of about 0.7% [4]. The percentage of iron oxide was low, ranging from 1.5% to 4%, this being the reason for weak magnetisation of the study area.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.52525101)the Tencent Xplorer Prize,the National Natural Science Foundation of China(Grant Nos.52450001 and 22409014)+3 种基金the International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52411540237)the Beijing Natural Science Foundation(Grant No.JQ18004),and the 111 Project(Grant No.B17002)Bingchao Qin acknowledges support from the China National Postdoctoral Program for Innovative Talents(Grant No.BX20230456)China Postdoctoral Science Foundation(Grant No.2024M754057).
文摘Thermoelectrics(TEs)possess the ability to directly convert heat into electricity and vice versa,making them highly promising for applications in power generation and solid-state cooling.Optimizing the transport properties is crucial for TE technology,in which magnetism has provided a new degree of freedom in decoupling electron and phonon transports.This paper provides a comprehensive overview of recent advancements in magnetics-induced enhancement for both longitudinal and transverse TE systems.Initially,two key optimization strategies for longitudinal TE power generation are explored:enhancing non-magnetic TE performance in intrinsic magnetic materials and optimizing magnetic TE performance by utilizing extrinsic magnetism-induced effects.Following this,the mechanism by which external magnetic fields enhance transverse TE conversion is explained in detail.Moreover,we discuss in depth how magnetism influences the electron and phonon transports from a physical perspective.Finally,the promising applications of magnetics-induced TE technology in both power generation and solid-state cooling are discussed,with some key challenges being proposed.
基金financially supported by the National Key R&D Program of China(No.2022YFA1402600)the National Natural Science Foundation of China(Nos.12304150 and 52161135108)support by the National Science Centre(Poland)(No.2021/40/Q/ST5/00066)。
文摘The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific configuration of applied magnetics fields and current and can persist up to 20 K,much higher than the Ne'el temperature(T_(N)≈1.9 K).Experiments and first-principles calculations suggest that the observed large negative MR is derived from a magnetic field that reconstructs the band structure and induces a Weyl point,which changes the carrier concentration.
基金financially supported by the National Natural Science Foundation of China(52373271)Science,Technology and Innovation Commission of Shenzhen Municipality under Grant(KCXFZ20201221173004012)+1 种基金National Key Research and Development Program of Shaanxi Province(No.2023-YBNY-271)Open Testing Foundation of the Analytical&Testing Center of Northwestern Polytechnical University(2023T019).
文摘Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.
文摘Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have on our aging population.Posture and gait control does not happen automatically,as previously believed,but rather requires continuous involvement of central nervous mechanisms.To effectively exert control over the body,the brain must integrate multiple streams of sensory information,including visual,vestibular,and somatosensory signals.The mechanisms which underpin the integration of these multisensory signals are the principal topic of the present work.Existing multisensory integration theories focus on how failure of cognitive processes thought to be involved in multisensory integration leads to falls in older adults.Insufficient emphasis,however,has been placed on specific contributions of individual sensory modalities to multisensory integration processes and cross-modal interactions that occur between the sensory modalities in relation to gait and balance.In the present work,we review the contributions of somatosensory,visual,and vestibular modalities,along with their multisensory intersections to gait and balance in older adults and patients with Parkinson’s disease.We also review evidence of vestibular contributions to multisensory temporal binding windows,previously shown to be highly pertinent to fall risk in older adults.Lastly,we relate multisensory vestibular mechanisms to potential neural substrates,both at the level of neurobiology(concerning positron emission tomography imaging)and at the level of electrophysiology(concerning electroencephalography).We hope that this integrative review,drawing influence across multiple subdisciplines of neuroscience,paves the way for novel research directions and therapeutic neuromodulatory approaches,to improve the lives of older adults and patients with neurodegenerative diseases.
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Supported by the National Natural Science Foundation of China(52122708,51977105)Natural Science Foundation of Jiangsu Province,China(BK20200017).
文摘With the continuous development of power supplies toward miniaturization,light weights,and high levels of integration,research on high-frequency resonant conversion based on planar magnetics is becoming extensive.Combining the soft-switching characteristics of resonant converters with those of wide bandgap devices,the switching frequency can be increase to the MHz range,and the power density of the entire system can be improved considerably.However,higher switching frequencies impose new requirements for the structural design,loss distribution,and common mode(CM)noise suppression of passive magnetic components.Herein,a thorough survey of the-state-of-the-art of planar magnetics in high-frequency resonant converters is conducted.Printed circuit board winding-based planar magnetics,magnetic integration,and power-loss optimization strategies are summarized in detail.Suppression methods for CM noise in high-frequency planar magnetics are also clarified and discussed.An insight view into the future development of planar magnetics for high-frequency resonant converters is presented.
基金supported by the National Natural Science Foundation of China (41804067, 42174090, 42250101, and 42250103)the Science Research Project of the Hebei Education Department (BJK2024107)+3 种基金the Hebei Natural Science Foundation (D2022403044)the Opening Fund of the Key Laboratory of Geological Survey and Evaluation of the Ministry of Education (GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources (MSFGPMR2022-4)the Excellent Young Scientist Fund of Hebei GEO University (YQ202403)。
文摘The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.
基金the China National Space Administration (CNSA) and the Macao Foundation for operating the MSS-1satelliteThis work has been carried out as part of ESA’s Swarm DISC activities funded by ESA contract no.4000109587.
文摘This article investigates the combination of magnetic data from the MSS-1 and Swarm satellites for improved investigations of Earth’s magnetic field and Geospace.The study highlights the complementary nature of polar-orbiting(Swarm)and low-inclination(MSS-1)satellites in geomagnetic modelling and monitoring large-scale magnetospheric contributions.Data from close encounters between MSS-1 and Swarm(intersatellite distance<100 km)confirm the excellent data quality of the two satellite missions(<1 nT median difference in scalar intensity F)and allow for data calibration and validation and investigations of in-situ ionospheric currents.The reason for a small but consistent difference(F as measured by MSS-1 is 0.5 to 1.0 nT larger than that measured by Swarm)is unknown.Combining MSS-1’s low-inclination data with Swarm’s near-polar observations significantly enhances the spatial-temporal resolution of Earth’s magnetic field models,allowing for new opportunities for studying both rapid core field variations at low latitudes and the local-time dependence of large-scale magnetospheric current systems.A joint analysis of magnetic data from six satellites during the May 2024 geomagnetic storm reveals a clear dawn-dusk asymmetry,with equatorial magnetic disturbances during dusk being approximately 150 nT more negative than during dawn.
基金supported by the Natural Science Research Project of the Anhui Educational Committee,China(No.2022AH050827)the Open Research Fund Program of Anhui Province Key Laboratory of Specialty Polymers,Anhui University of Science and Technology,China(No.AHKLSP23-12)the Joint National-Local Engineering Research Center for Safe and Precise Coal Mining Fund,China(No.EC2022020)。
文摘The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic frameworks(MOFs)are ideal self-sacrificing templates for the construction of carbon-based EMW absorbers.In this work,bimetallic FeMn-MOF-derived MnFe_(2)O_(4)/C/graphene composites were fabricated via a two-step route of solvothermal reaction and the following pyrolysis treatment.The results re-veal the evolution of the microscopic morphology of carbon skeletons from loofah-like to octahedral and then to polyhedron and pomegran-ate after the adjustment of the Fe^(3+)to Mn^(2+)molar ratio.Furthermore,at the Fe^(3+)to Mn^(2+)molar ratio of 2:1,the obtained MnFe_(2)O_(4)/C/graphene composite exhibited the highest EMW absorption capacity.Specifically,a minimum reflection loss of-72.7 dB and a max-imum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of 10wt%.In addition,the possible EMW absorp-tion mechanism of MnFe_(2)O_(4)/C/graphene composites was proposed.Therefore,the results of this work will contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.
