A novel electromagnetic probe array(EMPA) diagnostic, which consists of a magnetic probe array and an electrostatic probe array, has recently been developed on EAST. The EMPA is fixed near the first wall at horizontal...A novel electromagnetic probe array(EMPA) diagnostic, which consists of a magnetic probe array and an electrostatic probe array, has recently been developed on EAST. The EMPA is fixed near the first wall at horizontal port P. The magnetic probe array of the EMPA consists of 24 identical magnetic probes, each of them capable of measuring toroidal, poloidal and radial magnetic fluctuations simultaneously, providing additional toroidal magnetic fluctuation measurements compared with the regular magnetic probes on EAST. With a higher sampling rate and self-resonant frequency, the EMPA magnetic probes can provide higher frequency magnetic fluctuation measurements. The magnetic probe array of the EMPA is composed of two parallel layers of magnetic probes with a radial distance of 63 mm, and each layer of magnetic probes is arranged in four poloidal rows and three toroidal columns. The compact arrangement of the EMPA magnetic probe array largely improves the toroidal mode number measurement ability from-8≤ n≤ 8 to-112≤ n≤ 112, and also improves the high poloidal wave number measurement ability of magnetic fluctuations compared with the regular high frequency magnetic probes on EAST. The electrostatic probe array of the EMPA consists of two sets of four-tip probes and a single-tip probe array with three poloidal rows and four toroidal columns. It complements the electrostatic parameter measurements behind the main limiter and near the first wall in EAST. The engineering details of the EMPA diagnostic, including the mechanical system, the electrical system, the acquisition and control system, and the effective area calibration, are presented. The preliminary applications of the EMPA in L-mode and H-mode discharges on EAST have demonstrated that the EMPA works well for providing information on the magnetic and electrostatic fluctuations and can contribute to deeper physical analysis in future EAST experiments.展开更多
In human-machine interaction,robotic hands are useful in many scenarios.To operate robotic hands via gestures instead of handles will greatly improve the convenience and intuition of human-machine interaction.Here,we ...In human-machine interaction,robotic hands are useful in many scenarios.To operate robotic hands via gestures instead of handles will greatly improve the convenience and intuition of human-machine interaction.Here,we present a magnetic array assisted sliding triboelectric sensor for achieving a real-time gesture interaction between a human hand and robotic hand.With a finger’s traction movement of flexion or extension,the sensor can induce positive/negative pulse signals.Through counting the pulses in unit time,the degree,speed,and direction of finger motion can be judged in realtime.The magnetic array plays an important role in generating the quantifiable pulses.The designed two parts of magnetic array can transform sliding motion into contact-separation and constrain the sliding pathway,respectively,thus improve the durability,low speed signal amplitude,and stability of the system.This direct quantization approach and optimization of wearable gesture sensor provide a new strategy for achieving a natural,intuitive,and real-time human-robotic interaction.展开更多
In this paper,we propose the decoupling technique of patch antenna array by suppressing near-field magnetic coupling(NFMC) using magnetic metamaterials.To this end,a highly-integrated magnetic metamaterials,the subs...In this paper,we propose the decoupling technique of patch antenna array by suppressing near-field magnetic coupling(NFMC) using magnetic metamaterials.To this end,a highly-integrated magnetic metamaterials,the substrate-integrated split-ring resonator(SI-SRR),is firstly proposed to achieve negative permeability at the antenna operating frequency.By integrating SI-SRR in between two closely spaced antennas,magnetic fields are blocked in the shared substrate due to negative permeability of SI-SRR,reducing NFMC between the two antennas.To verify the technique,a prototype was fabricated and measured.The measured results demonstrated that the isolation can be enhanced by more than 17 dB even when the gap between the two patch antennas is only about 0.067 A.Due to high integration,this technique provides an effective alternative to high-isolation antenna array.展开更多
In order to improve the operation efficiency of coaxial magnetic gear(CMG),in this paper,a CMG model with slotted in magnetic modulation ring is proposed.In this model,the permanent magnets(PMs)of internal and externa...In order to improve the operation efficiency of coaxial magnetic gear(CMG),in this paper,a CMG model with slotted in magnetic modulation ring is proposed.In this model,the permanent magnets(PMs)of internal and external rotors are distributed in Halbach array,the inner rotor PMs are equally divided into 3 small pieces,and the outer rotor PMs are equally divided into 2 small pieces.At the same time,the static magnetic modulation ring iron blocks are slotted,each iron block has 3 slots,the width of the slot is 0.4°,and the depth of the single side slot is 1mm.Finally,a two-dimensional model is established,and the eddy current loss and iron loss of the model are optimized,compared with the conventional CMG model,it is found that the changed pattern can increase the internal and external output torque by 4%and 4.12%,respectively.The eddy current loss is reduced by 66.57%,and the iron loss is reduced by 8.9%,which significantly improve the operation efficiency of the CMG.展开更多
We propose a wire configuration to create a one-dimensional (1D) array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigz...We propose a wire configuration to create a one-dimensional (1D) array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigzag wire. We simulate the performance of this pattern by the finite element method which can take both the width and depth of the wire into consideration. The result of simulation shows that this configuration can create magnetic microtraps which can be separated and combined by changing bias magnetic field. We manage to split Z-wire trap and prove that similar result can occur for the new wire configuration. The fabrication processes of the atom chip are also introduced. Finally we discuss the loading method.展开更多
The ground state of a two-dimensional square superconducting πring array has been investigated. The circulating currents of the π ring array will spontaneously magnetize to the 'antiferromagnetic' arrangement wit...The ground state of a two-dimensional square superconducting πring array has been investigated. The circulating currents of the π ring array will spontaneously magnetize to the 'antiferromagnetic' arrangement with directions of the nearest-neighbouring currents circulating oppositely in the absence of an external magnetic field. It is found that the external magnetic field could destroy the anti-parallel configuration effectively. The external magnetic field needed to destroy the anti-parallel configuration is related to the superconducting π ring's inductance parameter β= 2πLIc/Ф0. For a small β the anti-parallel configuration, which is the lowest-energy ground state of the system, will be fully destroyed and changed to the configuration that the circulating currents have the same direction and parallel to the external magnetic field when the magnetic flux reaches Ф0/4 in each ring. Moreover, the magnetic field needed to destroy the anti-parallel configuration will be very small when β is large enough.展开更多
In this paper a new spherical actuator is designed and its advantages are compared to an existing spherical actuator, which function is limited by several design bottlenecks. First the output torque is too small. Seco...In this paper a new spherical actuator is designed and its advantages are compared to an existing spherical actuator, which function is limited by several design bottlenecks. First the output torque is too small. Second, the attitude is difficult to be accurately detected. The new three-dimen- sional magnetic pole array can solve these major problems. The new actuator features an outer rotor with multiple permanent magnet (PM) poles. Using an analytical solution and the finite element so- lution simulation, the feasibility of the approach is verified. A prototype was developed, tested, and experiments were conducted to obtain the practical value of the magnetic flux density.展开更多
Generally, a magnetic target can be described with six parameters, three describing the position and three describing the magnetic moment. Due to a lack of sufficient components from one magnetometer, we need more tha...Generally, a magnetic target can be described with six parameters, three describing the position and three describing the magnetic moment. Due to a lack of sufficient components from one magnetometer, we need more than one magnetometer when locating the magnetic target. Thus, a magnetometer array should be designed. The baseline of the array is an important factor that affects the localization accuracy of the target. In this paper, we focus on the localization of a static target by using a scalar magnetometer array. We present the scalar magnetometer array with a cross-shaped structure.We propose a method of determining the optimal baseline according to the parameters of the magnetometer and detection requirements. In the method, we use the traditional signal-to-noise ratio(SNR) as a performance index, and obtain the optimal baseline of the array by using the Monte Carlo method. The proposed method of determining the optimal baseline is verified in simulation. The arrays with different baselines are used to locate a static magnetic target. The results show that the location performance is better when using the array with the optimal baseline determined by the proposed method.展开更多
Ordered Ni70Fe30 nanowire array was fabricated in a porous alumina template by alternating current electrodeposition. The structural and magnetic properties of the as-obtained nanowire array were investigated by SEM, ...Ordered Ni70Fe30 nanowire array was fabricated in a porous alumina template by alternating current electrodeposition. The structural and magnetic properties of the as-obtained nanowire array were investigated by SEM, TEM, XRD, EDS and VSM. The results indicate that the as-obtained Ni70Fe30 nanowires exhibit a diameter of about 69.9 nm and aspect ratio of more than 60. Meanwhile, a preferred orientation [110] of bcc lattice was observed. The as-obtained nanowire array has an obvious magnetic anisotropy, of which the easy direction is perpendicular to the surface of the array. Moreover, after annealed, the Ni70Fe30 nanowire array exhibits an enhanced magnetic anisotropy.展开更多
Spot welding is affected by many factors and is difficult to monitor the nugget information with single sensor. In this paper, a new monitor system based on sensors array technique was developed for spot welding quali...Spot welding is affected by many factors and is difficult to monitor the nugget information with single sensor. In this paper, a new monitor system based on sensors array technique was developed for spot welding quality detection. The key part in the system is cross magnetic sensor array. It is composed of six magnetic sensors. An improved algorithm was proposed to extract the signal eigenvalue, which was based on principle component analysis. The results show that in the case of the 60 mm experiment, cross magnetic sensor array works well. And when the eigenvalues range of the cross magnetic sensor array is 0. 090 1 - 0. 098 2, the spots quality is good. The analysis of the eigenvalues of the cross magnetic sensor array allows us to determine whether the spot qualty is good or bad.展开更多
The advance of Inducive Power Transfer (IPT) system is capable to transfer large power across an air gap of sufficient distance, but the power level and charging area of receiver are limited by the magnetic coupler of...The advance of Inducive Power Transfer (IPT) system is capable to transfer large power across an air gap of sufficient distance, but the power level and charging area of receiver are limited by the magnetic coupler of IPT system. This paper analyses the correlative factors which effect maximum output power (Pm), it reveals Pm is inversely proportional with magnetic flux of power receiving coils. New ferrite array structure is proposed as the basic part of magnetic coupler that focusing on enhancing the equilibrium of magnetic flux distribution at charging area and increasing power transfer distance. The method of winding on ferrite array is quite flexible and the power transmission distance can be increased by changing the mode of ferrite array windings while magnetic field uniform is reduced, users can chose the suitable mode of winding for different IPT system. Finally the validity of theory analysis is tested by a 3D finite element modeling tool.展开更多
Two-dimensional double nanoparticle (DNP) arrays are demonstrated theoretically, supporting the interaction between out-of-plane magnetic plasmons and in-plane lattice resonances, which can be achieved by tuning the...Two-dimensional double nanoparticle (DNP) arrays are demonstrated theoretically, supporting the interaction between out-of-plane magnetic plasmons and in-plane lattice resonances, which can be achieved by tuning the nanoparticle height or the array period due to the height-dependent magnetic resonance and the periodicity-dependent lattice resonance. The interplay between the two plasmon modes can lead to a remarkable change in resonance lineshape and an improvement on magnetic field enhancement. Simultaneous electric field and magnetic field enhancement can be obtained in the gap region between neighboring particles at two resonance frequencies as the interplay occurs, which presents “open” cavities as electromagnetic field hot spots for potential applications on detection and sensing. The results not only offer an attractive way to tune the optical responses of plasmonic nanostructure, but also provide further insight into the plasmon interactions in periodic nanostructure or metamaterials comprising multiple elements.展开更多
Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly sol...Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation.Herein,we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets,oil droplets and water-in-oil droplets.Water-in-oil droplets provide an enclosed space for water droplets,preventing the evaporation in an open environment.Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance.The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer.The micropillars irradiated by a near-infrared laser bend under the magnetic force,while the unirradiated micropillars still keep their original shape.In the absence of a magnetic field,when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature,the micropillars return to their initial shape.In this process,the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.展开更多
The measurement system is the main equipment of the project.Based on the characteristic of experiment system,a sensor array is designed,and used to continually acquire the global magnetic field.A scientific scheme is ...The measurement system is the main equipment of the project.Based on the characteristic of experiment system,a sensor array is designed,and used to continually acquire the global magnetic field.A scientific scheme is developed to get the signal processing and temperature compensation for nondirective weak magnetic field.The software of sampling control system is given,which is complied using C language in Labwindows/CVI.Taking computer as main engine,the system can acquire the nondirective weak magnetic field automatically and continuously use the sensor array,the change of magnetic field can be shown in real-time and intuitively.展开更多
A method for identification of pulsations in time series of magnetic field data which are simultaneously present in multiple channels of data at one or more sensor locations is described. Candidate pulsations of inter...A method for identification of pulsations in time series of magnetic field data which are simultaneously present in multiple channels of data at one or more sensor locations is described. Candidate pulsations of interest are first identified in geomagnetic time series by inspection. Time series of these "training events" are represented in matrix form and transpose-multiplied to generate time- domain covariance matrices. The ranked eigenvectors of this matrix are stored as a feature of the pulsation. In the second stage of the algorithm, a sliding window (approxi- mately the width of the training event) is moved across the vector-valued time-series comprising the channels on which the training event was observed. At each window position, the data covariance matrix and associated eigen- vectors are calculated. We compare the orientation of the dominant eigenvectors of the training data to those from the windowed data and flag windows where the dominant eigenvectors directions are similar. This was successful in automatically identifying pulses which share polarization and appear to be from the same source process. We apply the method to a case study of continuously sampled (50 Hz) data from six observatories, each equipped with three- component induction coil magnetometers. We examine a 90-day interval of data associated with a cluster of four observatories located within 50 km of Napa, California, together with two remote reference stations-one 100 km to the north of the cluster and the other 350 km south. When the training data contains signals present in the remote reference observatories, we are reliably able to identify and extract global geomagnetic signals such as solar-generated noise. When training data contains pulsations only observed in the cluster of local observatories, we identify several types of non-plane wave signals having similar polarization.展开更多
Magnetically levitated stages(MLS) have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom(DOF) motions have co...Magnetically levitated stages(MLS) have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom(DOF) motions have coupling relationship with each current of coil array, and this coupling is still associated with the relative positions between the mover and the stator of the stage. So it is quite difficult to control the 6-DOF motions of the stage. By reasonable commutation of coil array, this complicated coupling relationship can be decoupled. The analytical force/torque-decomposing model of the stage is established first. Then the initial currents of coil array are commutated based on the pseudo inverse of the analytical force/torque-decomposing model matrix. And then the coil array currents are commutated again with different current bounds given to the initial currents as well as in the sense of minimum 2-norm of currents vector. Using the long stroke magnetically levitated stage with moving coils under investigation as examples, the currents of coil array are commutated with different current bounds adopting the proposed commutation method, the determination of current bound and the current bounds' influences on the heat-losses in coil array are analyzed, and the effectiveness of implementation algorithm of proposed commutation method is discussed. Simulation, analysis and discussion results indicate that the currents of coil array within the given current bound can be solved analytically by proposed commutation method, and the implementation algorithm does not need any searching or iteration. By the current-bounded commutation method proposed, the amplitude of coil array currents can be limited within an appropriate current bound(This is very beneficial to the improvement of the reliability and motion performance of the stage), as well as these currents can also generate the desired forces and torques.展开更多
The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s f...The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.展开更多
The construction of modern livable cities faces challenges in karst areas,including ground collapse and engineering problems.Wuhan,with a population of 13.74×10^(6) and approximately 1161 km^(2)of soluble rocks i...The construction of modern livable cities faces challenges in karst areas,including ground collapse and engineering problems.Wuhan,with a population of 13.74×10^(6) and approximately 1161 km^(2)of soluble rocks in the urban area of 8569.15 km^(2),predominantly consists of concealed karst areas where occasional ground collapse events occur,posing significant threats to underground engineering projects.To address these challenges,a comprehensive geological survey was conducted in Wuhan,focusing on major karstrelated issues.Geophysical methods offer advantages over drilling in detecting concealed karst areas due to their efficiency,non-destructiveness,and flexibility.This paper reviewed the karst geological characteristics in Wuhan and the geophysical exploration methods for karst,selected eight effective geophysical methods for field experimentation,evaluated their suitability,and proposed method combinations for different karst scenarios.The results show that different geophysical methods have varying applicability for karst detection in Wuhan,and combining multiple methods enhances detection effectiveness.The specific recommendations for method combinations provided in this study serve as a valuable reference for karst detection in Wuhan.展开更多
This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in considerati...This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in consideration and the entire simulation is carried in Matlab/Simulink environment. The rated power for the generator is fixed at 1.5 KW and number of pole at 20. It is observed under low wind speed of6 m/s, a turbine having approximately1 mof radius and2.6 mof height develops 150 Nm mechanical torque that can generate power up to 1.5 KW. The generator is designed using modeling tool and is fabricated. The fabricated generator is tested in the laboratory with the simulation result for the error analysis. The range of error is about 5%-27% for the same output power value. The limitations and possible causes for error are presented and discussed.展开更多
A novel approach devoted to achieving ultra-wideband radar cross section reduction(RCSR) of a waveguide slot antenna array(WGSAA) while maintaining its radiation performance is proposed. Three kinds of artificial ...A novel approach devoted to achieving ultra-wideband radar cross section reduction(RCSR) of a waveguide slot antenna array(WGSAA) while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors(AMCs) tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.展开更多
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China (Nos. 2019YFE03030000 and 2022YFE03020004)National Natural Science Foundation of China (Nos. 12105187, 11905250 and 11975275)+1 种基金the China Postdoctoral Science Foundation (No. 2021M702245)the Users with Excellence Program of Hefei Science Center, CAS (No. 2021HSC-UE014)。
文摘A novel electromagnetic probe array(EMPA) diagnostic, which consists of a magnetic probe array and an electrostatic probe array, has recently been developed on EAST. The EMPA is fixed near the first wall at horizontal port P. The magnetic probe array of the EMPA consists of 24 identical magnetic probes, each of them capable of measuring toroidal, poloidal and radial magnetic fluctuations simultaneously, providing additional toroidal magnetic fluctuation measurements compared with the regular magnetic probes on EAST. With a higher sampling rate and self-resonant frequency, the EMPA magnetic probes can provide higher frequency magnetic fluctuation measurements. The magnetic probe array of the EMPA is composed of two parallel layers of magnetic probes with a radial distance of 63 mm, and each layer of magnetic probes is arranged in four poloidal rows and three toroidal columns. The compact arrangement of the EMPA magnetic probe array largely improves the toroidal mode number measurement ability from-8≤ n≤ 8 to-112≤ n≤ 112, and also improves the high poloidal wave number measurement ability of magnetic fluctuations compared with the regular high frequency magnetic probes on EAST. The electrostatic probe array of the EMPA consists of two sets of four-tip probes and a single-tip probe array with three poloidal rows and four toroidal columns. It complements the electrostatic parameter measurements behind the main limiter and near the first wall in EAST. The engineering details of the EMPA diagnostic, including the mechanical system, the electrical system, the acquisition and control system, and the effective area calibration, are presented. The preliminary applications of the EMPA in L-mode and H-mode discharges on EAST have demonstrated that the EMPA works well for providing information on the magnetic and electrostatic fluctuations and can contribute to deeper physical analysis in future EAST experiments.
基金This work was supported by National Natural Science Foundation of China(51902035 and 52073037)Natural Science Foundation of Chongqing(cstc2020jcyj-msxmX0807)+1 种基金the Fundamental Research Funds for the Central Universities(2020CDJ-LHSS-001 and 2019CDXZWL001)Chongqing graduate tutor team construction project(ydstd1832).
文摘In human-machine interaction,robotic hands are useful in many scenarios.To operate robotic hands via gestures instead of handles will greatly improve the convenience and intuition of human-machine interaction.Here,we present a magnetic array assisted sliding triboelectric sensor for achieving a real-time gesture interaction between a human hand and robotic hand.With a finger’s traction movement of flexion or extension,the sensor can induce positive/negative pulse signals.Through counting the pulses in unit time,the degree,speed,and direction of finger motion can be judged in realtime.The magnetic array plays an important role in generating the quantifiable pulses.The designed two parts of magnetic array can transform sliding motion into contact-separation and constrain the sliding pathway,respectively,thus improve the durability,low speed signal amplitude,and stability of the system.This direct quantization approach and optimization of wearable gesture sensor provide a new strategy for achieving a natural,intuitive,and real-time human-robotic interaction.
基金Project supported in part by the National Natural Science Foundation of China(Grant Nos.61331005,61471388,61501503,61501502,61501497,51575524,61302023,and 11304393)the Natural Science Foundation of Shaanxi Province,China(Grant Nos.2015JM6300 and 2015JM6277)
文摘In this paper,we propose the decoupling technique of patch antenna array by suppressing near-field magnetic coupling(NFMC) using magnetic metamaterials.To this end,a highly-integrated magnetic metamaterials,the substrate-integrated split-ring resonator(SI-SRR),is firstly proposed to achieve negative permeability at the antenna operating frequency.By integrating SI-SRR in between two closely spaced antennas,magnetic fields are blocked in the shared substrate due to negative permeability of SI-SRR,reducing NFMC between the two antennas.To verify the technique,a prototype was fabricated and measured.The measured results demonstrated that the isolation can be enhanced by more than 17 dB even when the gap between the two patch antennas is only about 0.067 A.Due to high integration,this technique provides an effective alternative to high-isolation antenna array.
基金supported in part by National Natural Science Foundation of China and China Postdoctoral Science Foundation.(Project No.51707072,2018M632855).
文摘In order to improve the operation efficiency of coaxial magnetic gear(CMG),in this paper,a CMG model with slotted in magnetic modulation ring is proposed.In this model,the permanent magnets(PMs)of internal and external rotors are distributed in Halbach array,the inner rotor PMs are equally divided into 3 small pieces,and the outer rotor PMs are equally divided into 2 small pieces.At the same time,the static magnetic modulation ring iron blocks are slotted,each iron block has 3 slots,the width of the slot is 0.4°,and the depth of the single side slot is 1mm.Finally,a two-dimensional model is established,and the eddy current loss and iron loss of the model are optimized,compared with the conventional CMG model,it is found that the changed pattern can increase the internal and external output torque by 4%and 4.12%,respectively.The eddy current loss is reduced by 66.57%,and the iron loss is reduced by 8.9%,which significantly improve the operation efficiency of the CMG.
基金Project supported by the National Basic Research Program of China(Grant No.2006CB921202)the National Natural Science Foundation of China(Grant No.10974210)
文摘We propose a wire configuration to create a one-dimensional (1D) array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigzag wire. We simulate the performance of this pattern by the finite element method which can take both the width and depth of the wire into consideration. The result of simulation shows that this configuration can create magnetic microtraps which can be separated and combined by changing bias magnetic field. We manage to split Z-wire trap and prove that similar result can occur for the new wire configuration. The fabrication processes of the atom chip are also introduced. Finally we discuss the loading method.
文摘The ground state of a two-dimensional square superconducting πring array has been investigated. The circulating currents of the π ring array will spontaneously magnetize to the 'antiferromagnetic' arrangement with directions of the nearest-neighbouring currents circulating oppositely in the absence of an external magnetic field. It is found that the external magnetic field could destroy the anti-parallel configuration effectively. The external magnetic field needed to destroy the anti-parallel configuration is related to the superconducting π ring's inductance parameter β= 2πLIc/Ф0. For a small β the anti-parallel configuration, which is the lowest-energy ground state of the system, will be fully destroyed and changed to the configuration that the circulating currents have the same direction and parallel to the external magnetic field when the magnetic flux reaches Ф0/4 in each ring. Moreover, the magnetic field needed to destroy the anti-parallel configuration will be very small when β is large enough.
基金Supported by the National Key Basic Research and Development Program(973 Program)(2014CB046405)
文摘In this paper a new spherical actuator is designed and its advantages are compared to an existing spherical actuator, which function is limited by several design bottlenecks. First the output torque is too small. Second, the attitude is difficult to be accurately detected. The new three-dimen- sional magnetic pole array can solve these major problems. The new actuator features an outer rotor with multiple permanent magnet (PM) poles. Using an analytical solution and the finite element so- lution simulation, the feasibility of the approach is verified. A prototype was developed, tested, and experiments were conducted to obtain the practical value of the magnetic flux density.
基金supported by the National Natural Science Foundation of China(Grant No.61174192)
文摘Generally, a magnetic target can be described with six parameters, three describing the position and three describing the magnetic moment. Due to a lack of sufficient components from one magnetometer, we need more than one magnetometer when locating the magnetic target. Thus, a magnetometer array should be designed. The baseline of the array is an important factor that affects the localization accuracy of the target. In this paper, we focus on the localization of a static target by using a scalar magnetometer array. We present the scalar magnetometer array with a cross-shaped structure.We propose a method of determining the optimal baseline according to the parameters of the magnetometer and detection requirements. In the method, we use the traditional signal-to-noise ratio(SNR) as a performance index, and obtain the optimal baseline of the array by using the Monte Carlo method. The proposed method of determining the optimal baseline is verified in simulation. The arrays with different baselines are used to locate a static magnetic target. The results show that the location performance is better when using the array with the optimal baseline determined by the proposed method.
文摘Ordered Ni70Fe30 nanowire array was fabricated in a porous alumina template by alternating current electrodeposition. The structural and magnetic properties of the as-obtained nanowire array were investigated by SEM, TEM, XRD, EDS and VSM. The results indicate that the as-obtained Ni70Fe30 nanowires exhibit a diameter of about 69.9 nm and aspect ratio of more than 60. Meanwhile, a preferred orientation [110] of bcc lattice was observed. The as-obtained nanowire array has an obvious magnetic anisotropy, of which the easy direction is perpendicular to the surface of the array. Moreover, after annealed, the Ni70Fe30 nanowire array exhibits an enhanced magnetic anisotropy.
基金This work was supported by Project of National 863 High Technology of China ( No. 2008AA04Z136 ), Project supported by the National Natural Science Foundation of China( No. 50975197).
文摘Spot welding is affected by many factors and is difficult to monitor the nugget information with single sensor. In this paper, a new monitor system based on sensors array technique was developed for spot welding quality detection. The key part in the system is cross magnetic sensor array. It is composed of six magnetic sensors. An improved algorithm was proposed to extract the signal eigenvalue, which was based on principle component analysis. The results show that in the case of the 60 mm experiment, cross magnetic sensor array works well. And when the eigenvalues range of the cross magnetic sensor array is 0. 090 1 - 0. 098 2, the spots quality is good. The analysis of the eigenvalues of the cross magnetic sensor array allows us to determine whether the spot qualty is good or bad.
文摘The advance of Inducive Power Transfer (IPT) system is capable to transfer large power across an air gap of sufficient distance, but the power level and charging area of receiver are limited by the magnetic coupler of IPT system. This paper analyses the correlative factors which effect maximum output power (Pm), it reveals Pm is inversely proportional with magnetic flux of power receiving coils. New ferrite array structure is proposed as the basic part of magnetic coupler that focusing on enhancing the equilibrium of magnetic flux distribution at charging area and increasing power transfer distance. The method of winding on ferrite array is quite flexible and the power transmission distance can be increased by changing the mode of ferrite array windings while magnetic field uniform is reduced, users can chose the suitable mode of winding for different IPT system. Finally the validity of theory analysis is tested by a 3D finite element modeling tool.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10974183,11104252,61274012,and 51072184)the Specialized Re-search Fund for the Doctoral Program of Higher Education of China(Grant No.20114101110003)+4 种基金the Aeronautical Science Foundation of China(Grant No.2011ZF55015)the Basic and Frontier Technology Research Program of Henan Province,China(Grant Nos.112300410264 and 122300410162)the Foundation of University Young Key Teacher from Henan Province,China(Grant No.2012GGJS-146)the Key Program of Science and Technology of Henan Education Department,China(Grant Nos.12A140014 and 13A140693)the Postdoctoral Research Sponsorship of Henan Province,China(Grant No.2011002)
文摘Two-dimensional double nanoparticle (DNP) arrays are demonstrated theoretically, supporting the interaction between out-of-plane magnetic plasmons and in-plane lattice resonances, which can be achieved by tuning the nanoparticle height or the array period due to the height-dependent magnetic resonance and the periodicity-dependent lattice resonance. The interplay between the two plasmon modes can lead to a remarkable change in resonance lineshape and an improvement on magnetic field enhancement. Simultaneous electric field and magnetic field enhancement can be obtained in the gap region between neighboring particles at two resonance frequencies as the interplay occurs, which presents “open” cavities as electromagnetic field hot spots for potential applications on detection and sensing. The results not only offer an attractive way to tune the optical responses of plasmonic nanostructure, but also provide further insight into the plasmon interactions in periodic nanostructure or metamaterials comprising multiple elements.
基金the Natural Science Foundation of China(No.21874015)the Fundamental Research Funds for the Central Universities(No.N2005024).
文摘Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation.Herein,we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets,oil droplets and water-in-oil droplets.Water-in-oil droplets provide an enclosed space for water droplets,preventing the evaporation in an open environment.Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance.The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer.The micropillars irradiated by a near-infrared laser bend under the magnetic force,while the unirradiated micropillars still keep their original shape.In the absence of a magnetic field,when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature,the micropillars return to their initial shape.In this process,the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.
基金Project(10672191)supported by the National Natural Science Foundation of ChinaProject(06JJ2059)supported by the Provincial Natural Science Foundation of Hunan,ChinaProject(KF0607) supported by the Key Laboratory of Low Dimensional Materials and Application Technology (Xiangtan University),Ministry of Education,China
文摘The measurement system is the main equipment of the project.Based on the characteristic of experiment system,a sensor array is designed,and used to continually acquire the global magnetic field.A scientific scheme is developed to get the signal processing and temperature compensation for nondirective weak magnetic field.The software of sampling control system is given,which is complied using C language in Labwindows/CVI.Taking computer as main engine,the system can acquire the nondirective weak magnetic field automatically and continuously use the sensor array,the change of magnetic field can be shown in real-time and intuitively.
文摘A method for identification of pulsations in time series of magnetic field data which are simultaneously present in multiple channels of data at one or more sensor locations is described. Candidate pulsations of interest are first identified in geomagnetic time series by inspection. Time series of these "training events" are represented in matrix form and transpose-multiplied to generate time- domain covariance matrices. The ranked eigenvectors of this matrix are stored as a feature of the pulsation. In the second stage of the algorithm, a sliding window (approxi- mately the width of the training event) is moved across the vector-valued time-series comprising the channels on which the training event was observed. At each window position, the data covariance matrix and associated eigen- vectors are calculated. We compare the orientation of the dominant eigenvectors of the training data to those from the windowed data and flag windows where the dominant eigenvectors directions are similar. This was successful in automatically identifying pulses which share polarization and appear to be from the same source process. We apply the method to a case study of continuously sampled (50 Hz) data from six observatories, each equipped with three- component induction coil magnetometers. We examine a 90-day interval of data associated with a cluster of four observatories located within 50 km of Napa, California, together with two remote reference stations-one 100 km to the north of the cluster and the other 350 km south. When the training data contains signals present in the remote reference observatories, we are reliably able to identify and extract global geomagnetic signals such as solar-generated noise. When training data contains pulsations only observed in the cluster of local observatories, we identify several types of non-plane wave signals having similar polarization.
基金supported by National Basic Research Program of China(973 Program, Grant No. 2009CB724205)National Hi-tech Research and Development Program of China(863 Program, Grant No. 2009AA04Z148)Independent Research Program of the State Key Laboratory of Tribology of China(Grant No. SKLT08B04)
文摘Magnetically levitated stages(MLS) have potentials to obtain good motion performances in high vacuum environment. Yet the electromagnetic forces/torques corresponding to six degrees of freedom(DOF) motions have coupling relationship with each current of coil array, and this coupling is still associated with the relative positions between the mover and the stator of the stage. So it is quite difficult to control the 6-DOF motions of the stage. By reasonable commutation of coil array, this complicated coupling relationship can be decoupled. The analytical force/torque-decomposing model of the stage is established first. Then the initial currents of coil array are commutated based on the pseudo inverse of the analytical force/torque-decomposing model matrix. And then the coil array currents are commutated again with different current bounds given to the initial currents as well as in the sense of minimum 2-norm of currents vector. Using the long stroke magnetically levitated stage with moving coils under investigation as examples, the currents of coil array are commutated with different current bounds adopting the proposed commutation method, the determination of current bound and the current bounds' influences on the heat-losses in coil array are analyzed, and the effectiveness of implementation algorithm of proposed commutation method is discussed. Simulation, analysis and discussion results indicate that the currents of coil array within the given current bound can be solved analytically by proposed commutation method, and the implementation algorithm does not need any searching or iteration. By the current-bounded commutation method proposed, the amplitude of coil array currents can be limited within an appropriate current bound(This is very beneficial to the improvement of the reliability and motion performance of the stage), as well as these currents can also generate the desired forces and torques.
文摘The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.
基金jointly supported by the project of Chinese National Natural Science Foundation(42107485)National Key R&D Program(2020YFC1512400,2018YFC800804)China Geological Survey(DD20190282,DD20221734,and DD20230323)。
文摘The construction of modern livable cities faces challenges in karst areas,including ground collapse and engineering problems.Wuhan,with a population of 13.74×10^(6) and approximately 1161 km^(2)of soluble rocks in the urban area of 8569.15 km^(2),predominantly consists of concealed karst areas where occasional ground collapse events occur,posing significant threats to underground engineering projects.To address these challenges,a comprehensive geological survey was conducted in Wuhan,focusing on major karstrelated issues.Geophysical methods offer advantages over drilling in detecting concealed karst areas due to their efficiency,non-destructiveness,and flexibility.This paper reviewed the karst geological characteristics in Wuhan and the geophysical exploration methods for karst,selected eight effective geophysical methods for field experimentation,evaluated their suitability,and proposed method combinations for different karst scenarios.The results show that different geophysical methods have varying applicability for karst detection in Wuhan,and combining multiple methods enhances detection effectiveness.The specific recommendations for method combinations provided in this study serve as a valuable reference for karst detection in Wuhan.
文摘This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in consideration and the entire simulation is carried in Matlab/Simulink environment. The rated power for the generator is fixed at 1.5 KW and number of pole at 20. It is observed under low wind speed of6 m/s, a turbine having approximately1 mof radius and2.6 mof height develops 150 Nm mechanical torque that can generate power up to 1.5 KW. The generator is designed using modeling tool and is fabricated. The fabricated generator is tested in the laboratory with the simulation result for the error analysis. The range of error is about 5%-27% for the same output power value. The limitations and possible causes for error are presented and discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61671464,61701523,and 61471389)
文摘A novel approach devoted to achieving ultra-wideband radar cross section reduction(RCSR) of a waveguide slot antenna array(WGSAA) while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors(AMCs) tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.