Non-hydrostatic stress plays a significant role in shaping the properties of materials under compression.High-pressure effects such as yielding deformation,phase transitions,and volume contraction can alter the pressu...Non-hydrostatic stress plays a significant role in shaping the properties of materials under compression.High-pressure effects such as yielding deformation,phase transitions,and volume contraction can alter the pressure distribution within the pressure chamber.However,due to the inherent size limitation of the diamond anvil cell(DAC),in situ high-pressure studies usually assume a hydrostatic environment,equaling the pressure of samples to a pressure calibrator inside the chamber.Accurately imaging pressure distribution within the DAC chamber remains challenging,particularly as the material undergoes phase transitions.Here,we present a method for mapping pressure distribution with high spatial resolution using wide-field optically detected magnetic resonance(ODMR)of nanodiamonds.The pressure gradients during the highpressure transition of zinc oxide(ZnO)were compared using both the multiple rubies technique and wide-field ODMR.The latter technique demonstrated superior spatial resolution,easier operation,and more detailed information.These results highlight the potential of wide-field ODMR as a powerful tool for precise pressure sensing,particularly in studies involving non-hydrostatic pressure conditions.展开更多
Magnetic flux leakage(MFL)testing technology has the advantages of simple principle,easy engineering implementation and low requirements on the surface of the detected workpiece.Therefore,it has been one of the resear...Magnetic flux leakage(MFL)testing technology has the advantages of simple principle,easy engineering implementation and low requirements on the surface of the detected workpiece.Therefore,it has been one of the research hotspots in the field of non-destructive testing(NDT)and widely used for testing long distance pipelines.This paper presents the development of MFL tesing technology from the aspects of basic theory,influencing factors,magnetization technology,signal processing,etc.The problems to be solved and the future development are summarized,which can provide reference for the research and system development of MFL testing technology.展开更多
A method of detecting the single channel triaxial magnetic field information based on diamond nitrogen-vacancy(NV)color center is introduced.Firstly,the incident angle of the bias magnetic field which can achieve the ...A method of detecting the single channel triaxial magnetic field information based on diamond nitrogen-vacancy(NV)color center is introduced.Firstly,the incident angle of the bias magnetic field which can achieve the equal frequency difference optically-detected magnetic resonance(ODMR)spectrum of diamond NV color center is calculated theoretically,and the triaxial magnetic information solution model is also constructed.Secondly,the microwave time-controlled circuit module is designed to generate equal timing and equal frequency difference microwave pulse signals in one channel.Combining with the optical detection magnetic resonance technology,the purpose of sequentially locking and detecting the four formant signals on one side of the diamond NV color center(m_(s)=-1 state signal)is achieved,and the vector magnetic field information detection is accomplished by combining the triaxial magnetic information solution model.The system can obtain magnetic field detection in a range of 0 mT-0.82 mT.The system's magnetic noise sensitivity is 14.2 nT/Hz^(1/2),and the deviation angle errors of magnetic field detectionθ_(x) andθ_(y) are 1.3° and 8.2° respectively.展开更多
We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy（NV） color center with a nearest neighbor ^13C nuclear spin in diamond to detect the strength and direction（includin...We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy（NV） color center with a nearest neighbor ^13C nuclear spin in diamond to detect the strength and direction（including both polar and azimuth angles） of a static vector magnetic field by optical detection magnetic resonance（ODMR） technique. With the known hyperfine coupling tensor between an NV center and a nearest neighbor ^13C nuclear spin, we show that the information of static vector magnetic field could be extracted by observing the pulsed continuous wave（CW） spectrum.展开更多
In the field of magnetic tile surface detection, artificial detection efficiency is low, and the traditional image segmentation algorithm cannot show good performance when the gray scale of the magnetic tile itself is...In the field of magnetic tile surface detection, artificial detection efficiency is low, and the traditional image segmentation algorithm cannot show good performance when the gray scale of the magnetic tile itself is small, or the image is affected by uneven illumination. In view of these questions, this paper puts forward a new clustering segmentation algorithm based on texture feature. This algorithm uses Gabor function spectra to represent magnetic tile surface texture and then uses a user-defined local product coefficient to modify Gabor energy spectra to get the center number of fuzzy C-means(FCM) clustering. Moreover, the user-defined Gabor energy spectra image is segmented by clustering algorithm. Finally, it extracts the magnetic tile surface defects according to the changes of regional gray characteristics. Experiments show that the algorithm effectively overcomes the noise interference and makes a good performance on accuracy and robustness, which can effectively detect crack,damage, pit and other defects on the magnetic tile surface.展开更多
Magnetically coupled resonant technology is a novel method for solving the breakpoint locating of power grounding grid.But the method can only detect breakpoints of a single mesh grounding grid at present.In this pape...Magnetically coupled resonant technology is a novel method for solving the breakpoint locating of power grounding grid.But the method can only detect breakpoints of a single mesh grounding grid at present.In this paper,a magnetically coupled resonant detection method for four-hole grounding grid breakpoint is proposed.Firstly,the equivalent circuit model of the four mesh grounding grid with two types of breakpoints,namely edge branch and intermediate branch,is established.The input impedance and phase angle of the system are obtained by analyzing the equivalent capacitance and equivalent resistance in the model.Secondly,the magnetically coupled resonant physical process of grounding grid faults is solved via HFSS software.The magnetic field intensity and phase frequency characteristic curves of four mesh holes with different branches and positions of breakpoints and different corrosion degrees are studied,and an experimental system is built to verify the feasibility.The results show that under the condition of grounding grid buried depth of 0.5 m and input frequency of 1~15MHz,and there is an inverse relationship between equivalent capacitance and distortion frequency,the phase angle is positively correlated with the degree of corrosion of grounding grid,and the error of signal distortion frequency can be positioned at 5%.This paper provides some ideas for the application of magnetic coupling grounding grid detection technology.展开更多
In order to solve the problem of low signal-to-noise ratio（about 15 d B） in magnetic signal acquisition of banknotes, a new method of magnetic signal acquisition and processing is proposed taking RMB as an example. ...In order to solve the problem of low signal-to-noise ratio（about 15 d B） in magnetic signal acquisition of banknotes, a new method of magnetic signal acquisition and processing is proposed taking RMB as an example. In this method, weak signa detection is performed to reduce the noise accompanied with the signal. Seven orders of Chebyshev（Ⅰ） filter and the anti-jamming technology are used in the PCB layout, and grounding modes are introduced to reduce the noise of the amplitude waveform. The proposed method reduce the final output noise by 2/3 and the sig nal-to-noise ratio is increased to 24 d B. The experimental results show that the magnetic signal of RMB banknotes are acquired by the circuit stability, which provides an important guarantee for the improvements of the anti-counterfeit and discrimination for banknotes performance.展开更多
We suggest an experimental scheme that a single nitrogen-vacancy（NV） center coupled to a nearest neighbor ^13C nucleus as a sensor in diamond can be used to detect a static vector magnetic field. By means of optical...We suggest an experimental scheme that a single nitrogen-vacancy（NV） center coupled to a nearest neighbor ^13C nucleus as a sensor in diamond can be used to detect a static vector magnetic field. By means of optical detection magnetic resonance（ODMR） technique, both the strength and the direction of the vector field could be determined by relevant resonance frequencies of continuous wave（CW） and Ramsey spectrums. In addition, we give a method that determines the unique one of eight possible hyperfine tensors for an（NV–^13C） system. Finally, we propose an unambiguous method to exclude the symmetrical solution from eight possible vector fields, which correspond to nearly identical resonance frequencies due to their mirror symmetry about ^14N–Vacancy–^13 C（^14N–V–^13C） plane.展开更多
The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with ...The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.展开更多
Optically levitated nano-particle with spins is a promising system for high-precision measurement and quantum information processing. We theoretically analyze the ratio between the fluctuation of particle's displa...Optically levitated nano-particle with spins is a promising system for high-precision measurement and quantum information processing. We theoretically analyze the ratio between the fluctuation of particle's displacement caused by spins in magnetic field and caused by molecular collisions of the residual air. When the ratio is larger than unity, the displacement fluctuation of spins flipping can be remarkably detected. By theoretical analysis and numerical simulation, we propose and validate a scheme for the detection of gradient of the magnetic field by levitating ferromagnetic nano-particle, and also put forward a realizable detection scheme of the single spin by levitating nano-diamond particle with single nitrogen-vacancy(NV) centers.展开更多
A novel magnetic field sensor based on optical fiber Mach-Zehnder interferometer(MZI) coated by magnetic fluid(MF) is proposed. The MZI consists of two spherical structures formed on standard single mode fiber(SMF). T...A novel magnetic field sensor based on optical fiber Mach-Zehnder interferometer(MZI) coated by magnetic fluid(MF) is proposed. The MZI consists of two spherical structures formed on standard single mode fiber(SMF). The interference wavelength and the power of the sensing structure are sensitive to the external refractive index(RI). Since RI of the MF is sensitive to the magnetic field, the magnetic field measurement can be realized by detecting the variation of the interference spectrum. Experimental results show that the wavelength and the power of interference dip both increase with the increase of magnetic field intensity.展开更多
Optically detected magnetic resonance(ODMR)has emerged as a powerful technique for quantum sensing,enabling high-sensitivity detection of physical quantities even at room temperature.Solid-state defects,such as nitrog...Optically detected magnetic resonance(ODMR)has emerged as a powerful technique for quantum sensing,enabling high-sensitivity detection of physical quantities even at room temperature.Solid-state defects,such as nitrogen-vacancy(NV)centers in diamond,have demonstrated remarkable capabilities in this domain[1–4].However,these systems are limited by their rigid lattice structures and lack tunability.展开更多
Wire ropes,employed extensively in coal mine hoists and transportation systems are subject to damage due to wear,corrosion and fatigue.The extent of damage and the carrying capacity of ropes are closely related to the...Wire ropes,employed extensively in coal mine hoists and transportation systems are subject to damage due to wear,corrosion and fatigue.The extent of damage and the carrying capacity of ropes are closely related to the sense of safety by staff and equipments.Magnetic flux leakage detection method(MFL),as an effective method,is these days widely used in detection of broken strands of wire ropes.In order to improve the accuracy of detection of flaws in wire ropes by magnetic flux leakage(MFL),the effect of the distance between a sensor and the surface of a wire rope(i.e.,lift-off) on detection by magnetic flux leakage was in-vestigated.An analysis of the main principles for the choice of lift-off is described by us and a new method that improves the structure of the detector is proposed from the point of view of the design of a magnetic circuit,to restrain the impact of fluctuations of sensor lift-off.The effect of this kind of method is validated by simulation and computation.The results show that the detection sensitivity is markedly increased by this method.Furthermore,the signal-to-noise ratio(SNR) can be increased by over 28%.This method will lend itself to offer reliable scientific information to optimize the structure of excitation devices and improve the accuracy of MFL detection.展开更多
High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which ...High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic performance.In order to solve these problems,a new signal demodulation method is proposed in this paper.The proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter parameters.In addition,a new magnetic polarity detection method is proposed,which is robust to current measurement noise.Finally,experiments verify the effectiveness of the method.展开更多
Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological explor...Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological exploration,featuring both hardware module integration and data processing methods.The hardware module incorporates a multi-rotor drone,a cesium optically pumped magnetometer,and a synchronized data acquisition system for processing magnetic and GPS position data.It can rapidly measure the magnetic field of the archaeological sites to capture the magnetic anomaly signals.The data processing methods consist of diurnal variation correction,survey line correction,aeromagnetic noise suppression,and a leveling algorithm based on curvelet transform,which is capable of identifying magnetic anomaly signals within the measured magnetic field.Field tests were conducted at the Song Dynasty iron smelting site in Xiacaopu,Anxi County,Fujian Province,China,where the system successfully discovered a new smelting furnace relic,which was subsequently confirmed through excavation.展开更多
A Two-Dimensional Convolutional Neural Network(2D-CNN)-based multi-feature fusion detection method is proposed to improve the detection performance of the submarine wake magnetic anomaly in view of its characteristics...A Two-Dimensional Convolutional Neural Network(2D-CNN)-based multi-feature fusion detection method is proposed to improve the detection performance of the submarine wake magnetic anomaly in view of its characteristics of low frequency and low signal-to-noise ratio(SNR).The method involves pre-processing the original signal by using the Savitzky-Golay(S-G)filter,followed by Residual Structure processing to extract the time-domain information,FFT to extract the frequency domain information and Minimum-Entropy Filter(MEF)for noise analysis.The 2D-CNN model with three processing branches is utilised for further feature extraction and signal judgement.To train the method,Simulated target signal dataset is obtained through the submarine wake magnetic anomaly simulation model,and the simulated original signal is acquired by stacking measured noise.The proposed method exhibits great detection performance for signals with different Signal-to-Noise Ratios(SNRs)and various types of noise,achieving a recognition accuracy of 90% for signals with SNRs above-10dB.The theoretical detection range of the submarine has been increased to over 1 km,outperforming similar neural networks based on magnetic dipole models.展开更多
To aid the magnetic anomaly detection(MAD)of underground ferromagnetic pipelines,this paper proposes a geometric modeling method based on the magnetic dipole reconstruction method(MDRM).First,the numerical modeling of...To aid the magnetic anomaly detection(MAD)of underground ferromagnetic pipelines,this paper proposes a geometric modeling method based on the magnetic dipole reconstruction method(MDRM).First,the numerical modeling of basic pipe components such as straight sections,bends and elbows,and tee joints are discussed and the relevant mathematical formulations for these components are derived.Next,after analyzing the function of MDRM and various element division strategies,the sectional division and blocked division methods are introduced and applied to the appropriate pipeline components to determine the volume and center coordinates of each element,establishing the general models for the three typical pipeline components considered.The resulting volume and center coordinates of each component are the fundamental parameters for determining the MAD forwarding of underground ferromagnetic pipelines using the MDRM.Finally,based on the combination and transformation of the basic pipeline components considered,the visualized geometric models of typical pipeline layouts including parallel pipelines,pipelines with elbows,and a pipeline with a tee joint are constructed.The results demonstrate the feasibility of the proposed method of geometric modeling for the MDRM,which can be further applied to the finite element modeling of these and other components when analyzing MAD data.Furthermore,the models with output parameters proposed in this paper establish a foundation for the inversion of MAD.展开更多
Nuclear magnetic resonance gyroscopes （NMRGs） are a kind of rotation-speed sensor that senses the angular velocity by measuring a frequency shift in the Larmor pre- cession of the nuclear spin in a constant magnetic...Nuclear magnetic resonance gyroscopes （NMRGs） are a kind of rotation-speed sensor that senses the angular velocity by measuring a frequency shift in the Larmor pre- cession of the nuclear spin in a constant magnetic field.展开更多
Hyperbolic metamaterials(HMMs) are novel artificial materials that excite the surface plasmon resonance(SPR) because of their unique hyperbolic dispersion properties. Herein, to the best of our knowledge, we propose t...Hyperbolic metamaterials(HMMs) are novel artificial materials that excite the surface plasmon resonance(SPR) because of their unique hyperbolic dispersion properties. Herein, to the best of our knowledge, we propose the first HMM-based fiber SPR(HMM-SPR) sensor for vector magnetic detection. By selecting the composite materials and structural parameters of the HMM dispersion management, HMM-SPR sensors can achieve a high refractive index sensitivity of 14.43 μm/RIU. Vector magnetic field detection was performed with the HMM-SPR sensor encapsulated with a magnetic fluid. Compared with other ferrofluidbased magnetic field fiber sensors, the proposed sensor shows pronounced advantages in intensity and direction sensitivity of 1.307 nm/Oe and 7.116 nm/°, respectively. The sensor design approach presented in this paper provides an excellent demonstration of HMM-SPR sensors in various applications.展开更多
With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typi...With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typical weak magnetic anomaly target,and their magnetic anomaly detection can only be realized within a certain distance.At present,a towfish or an autonomous underwater vehicle(AUV)is mainly used as the platform to equip magnetometers close to the submarine pipelines for magnetic anomaly detection.However,the mother ship directly affects the towfish,thus causing control interference.The AUV cannot detect in real time,which affects the magnetic anomaly detection and creates problems regarding detection efficiency.Meanwhile,a two-part towed platform has convenient control,thus reducing the interference of the towed mother ship and real-time detection.If the platform can maintain constant altitude sailing through the controller,the data accuracy in the actual magnetic anomaly detection can be guaranteed.On the basis of a two-part towed platform,a magnetic detection system with constant altitude sailing ability for submarine pipelines was constructed in this study.In addition,experimental verification was conducted.The experimental verification research shows that the constant altitude sailing experiment of the two-part towed platform verifies that the platform has good constant altitude sailing ability in both a hydrostatic environment and the actual marine environment.Meanwhile,the offshore magnetic anomaly detection experiment of submarine pipelines verifies the stable measurement function of the magnetic field and the function of the system to detect magnetic anomaly of submarine pipelines.展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFE0105200)the National Natural Science Foundation of China(Grant Nos.62422408,12374016,12174348,62271450,62027816,12422413,and 62475242).
文摘Non-hydrostatic stress plays a significant role in shaping the properties of materials under compression.High-pressure effects such as yielding deformation,phase transitions,and volume contraction can alter the pressure distribution within the pressure chamber.However,due to the inherent size limitation of the diamond anvil cell(DAC),in situ high-pressure studies usually assume a hydrostatic environment,equaling the pressure of samples to a pressure calibrator inside the chamber.Accurately imaging pressure distribution within the DAC chamber remains challenging,particularly as the material undergoes phase transitions.Here,we present a method for mapping pressure distribution with high spatial resolution using wide-field optically detected magnetic resonance(ODMR)of nanodiamonds.The pressure gradients during the highpressure transition of zinc oxide(ZnO)were compared using both the multiple rubies technique and wide-field ODMR.The latter technique demonstrated superior spatial resolution,easier operation,and more detailed information.These results highlight the potential of wide-field ODMR as a powerful tool for precise pressure sensing,particularly in studies involving non-hydrostatic pressure conditions.
基金National Natural Science Foundation of China(No.51804267)Applied Basic Research Project of Sichuan Province(No.2017JY0162)。
文摘Magnetic flux leakage(MFL)testing technology has the advantages of simple principle,easy engineering implementation and low requirements on the surface of the detected workpiece.Therefore,it has been one of the research hotspots in the field of non-destructive testing(NDT)and widely used for testing long distance pipelines.This paper presents the development of MFL tesing technology from the aspects of basic theory,influencing factors,magnetization technology,signal processing,etc.The problems to be solved and the future development are summarized,which can provide reference for the research and system development of MFL testing technology.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51635011, 51805493, 51775522, 51727808, and 51922009)the Applied Basic Research Program in Shanxi Province,China (Grant No. 201901D111011(ZD))+3 种基金the Key Research and Development Program in Shanxi Province,China(Grant No. 201803D121067)the Fund from the Key Laboratory for Information Detection and Processing of Shanxi Province,China (Grant No. ISPT2020-2)the Fund from the Key Laboratory of Shanxi Province,China (Grant No. 201905D121001)the Shanxi “1331 Project” Key Subjects Construction,China
文摘A method of detecting the single channel triaxial magnetic field information based on diamond nitrogen-vacancy(NV)color center is introduced.Firstly,the incident angle of the bias magnetic field which can achieve the equal frequency difference optically-detected magnetic resonance(ODMR)spectrum of diamond NV color center is calculated theoretically,and the triaxial magnetic information solution model is also constructed.Secondly,the microwave time-controlled circuit module is designed to generate equal timing and equal frequency difference microwave pulse signals in one channel.Combining with the optical detection magnetic resonance technology,the purpose of sequentially locking and detecting the four formant signals on one side of the diamond NV color center(m_(s)=-1 state signal)is achieved,and the vector magnetic field information detection is accomplished by combining the triaxial magnetic information solution model.The system can obtain magnetic field detection in a range of 0 mT-0.82 mT.The system's magnetic noise sensitivity is 14.2 nT/Hz^(1/2),and the deviation angle errors of magnetic field detectionθ_(x) andθ_(y) are 1.3° and 8.2° respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11305074,11135002,and 11275083)the Key Program of the Education Department Outstanding Youth Foundation of Anhui Province,China(Grant No.gxyq ZD2017080)the Education Department Natural Science Foundation of Anhui Province,China(Grant No.KJHS2015B09)
文摘We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy（NV） color center with a nearest neighbor ^13C nuclear spin in diamond to detect the strength and direction（including both polar and azimuth angles） of a static vector magnetic field by optical detection magnetic resonance（ODMR） technique. With the known hyperfine coupling tensor between an NV center and a nearest neighbor ^13C nuclear spin, we show that the information of static vector magnetic field could be extracted by observing the pulsed continuous wave（CW） spectrum.
基金the National Natural Science Foundation of China(Nos.51307003 and 61601004)
文摘In the field of magnetic tile surface detection, artificial detection efficiency is low, and the traditional image segmentation algorithm cannot show good performance when the gray scale of the magnetic tile itself is small, or the image is affected by uneven illumination. In view of these questions, this paper puts forward a new clustering segmentation algorithm based on texture feature. This algorithm uses Gabor function spectra to represent magnetic tile surface texture and then uses a user-defined local product coefficient to modify Gabor energy spectra to get the center number of fuzzy C-means(FCM) clustering. Moreover, the user-defined Gabor energy spectra image is segmented by clustering algorithm. Finally, it extracts the magnetic tile surface defects according to the changes of regional gray characteristics. Experiments show that the algorithm effectively overcomes the noise interference and makes a good performance on accuracy and robustness, which can effectively detect crack,damage, pit and other defects on the magnetic tile surface.
基金supported by the Science and Technology Research Innovation Team Project LT2019007 of the Department of Education of Liaoning Provincethe Discipline Innovation Team Project LNTU20TD-02,29 of Liaoning Technical University。
文摘Magnetically coupled resonant technology is a novel method for solving the breakpoint locating of power grounding grid.But the method can only detect breakpoints of a single mesh grounding grid at present.In this paper,a magnetically coupled resonant detection method for four-hole grounding grid breakpoint is proposed.Firstly,the equivalent circuit model of the four mesh grounding grid with two types of breakpoints,namely edge branch and intermediate branch,is established.The input impedance and phase angle of the system are obtained by analyzing the equivalent capacitance and equivalent resistance in the model.Secondly,the magnetically coupled resonant physical process of grounding grid faults is solved via HFSS software.The magnetic field intensity and phase frequency characteristic curves of four mesh holes with different branches and positions of breakpoints and different corrosion degrees are studied,and an experimental system is built to verify the feasibility.The results show that under the condition of grounding grid buried depth of 0.5 m and input frequency of 1~15MHz,and there is an inverse relationship between equivalent capacitance and distortion frequency,the phase angle is positively correlated with the degree of corrosion of grounding grid,and the error of signal distortion frequency can be positioned at 5%.This paper provides some ideas for the application of magnetic coupling grounding grid detection technology.
基金Supported by the project of image recognition and control system in class A machine(HT201403)
文摘In order to solve the problem of low signal-to-noise ratio（about 15 d B） in magnetic signal acquisition of banknotes, a new method of magnetic signal acquisition and processing is proposed taking RMB as an example. In this method, weak signa detection is performed to reduce the noise accompanied with the signal. Seven orders of Chebyshev（Ⅰ） filter and the anti-jamming technology are used in the PCB layout, and grounding modes are introduced to reduce the noise of the amplitude waveform. The proposed method reduce the final output noise by 2/3 and the sig nal-to-noise ratio is increased to 24 d B. The experimental results show that the magnetic signal of RMB banknotes are acquired by the circuit stability, which provides an important guarantee for the improvements of the anti-counterfeit and discrimination for banknotes performance.
基金Protect supported by the National Natural Science Foundation of China(Grant Nos.11305074,11135002,and 11275083)the Key Program of the Education Department Outstanding Youth Foundation of Anhui Province,China(Grant No.gxyq ZD2017080)the Natural Science Foundation of Anhui Province,China(Grant No.KJHS2015B09)
文摘We suggest an experimental scheme that a single nitrogen-vacancy（NV） center coupled to a nearest neighbor ^13C nucleus as a sensor in diamond can be used to detect a static vector magnetic field. By means of optical detection magnetic resonance（ODMR） technique, both the strength and the direction of the vector field could be determined by relevant resonance frequencies of continuous wave（CW） and Ramsey spectrums. In addition, we give a method that determines the unique one of eight possible hyperfine tensors for an（NV–^13C） system. Finally, we propose an unambiguous method to exclude the symmetrical solution from eight possible vector fields, which correspond to nearly identical resonance frequencies due to their mirror symmetry about ^14N–Vacancy–^13 C（^14N–V–^13C） plane.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFB3202800 and 2023YF0718400)Chinese Academy of Sciences(Grant No.ZDZBGCH2021002)+2 种基金Chinese Academy of Sciences(Grant No.GJJSTD20200001)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303204)Anhui Initiative in Quantum Information Technologies,USTC Tang Scholar,and the Fundamental Research Funds for the Central Universities.
文摘The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11374032,61435007,and 11704026the Joint Fund of the Ministry of Education of China under Grant No.6141A02011604+1 种基金NSAF(China)under Grant No.U1530401National Key Research and Development Program of China under Grant No.2016YFA0301201
文摘Optically levitated nano-particle with spins is a promising system for high-precision measurement and quantum information processing. We theoretically analyze the ratio between the fluctuation of particle's displacement caused by spins in magnetic field and caused by molecular collisions of the residual air. When the ratio is larger than unity, the displacement fluctuation of spins flipping can be remarkably detected. By theoretical analysis and numerical simulation, we propose and validate a scheme for the detection of gradient of the magnetic field by levitating ferromagnetic nano-particle, and also put forward a realizable detection scheme of the single spin by levitating nano-diamond particle with single nitrogen-vacancy(NV) centers.
基金supported by the National Training Programs of Innovation and Entrepreneurship for Undergraduates of China(No.201310060015)Education Program(No.YB11-32)
文摘A novel magnetic field sensor based on optical fiber Mach-Zehnder interferometer(MZI) coated by magnetic fluid(MF) is proposed. The MZI consists of two spherical structures formed on standard single mode fiber(SMF). The interference wavelength and the power of the sensing structure are sensitive to the external refractive index(RI). Since RI of the MF is sensitive to the magnetic field, the magnetic field measurement can be realized by detecting the variation of the interference spectrum. Experimental results show that the wavelength and the power of interference dip both increase with the increase of magnetic field intensity.
文摘Optically detected magnetic resonance(ODMR)has emerged as a powerful technique for quantum sensing,enabling high-sensitivity detection of physical quantities even at room temperature.Solid-state defects,such as nitrogen-vacancy(NV)centers in diamond,have demonstrated remarkable capabilities in this domain[1–4].However,these systems are limited by their rigid lattice structures and lack tunability.
文摘Wire ropes,employed extensively in coal mine hoists and transportation systems are subject to damage due to wear,corrosion and fatigue.The extent of damage and the carrying capacity of ropes are closely related to the sense of safety by staff and equipments.Magnetic flux leakage detection method(MFL),as an effective method,is these days widely used in detection of broken strands of wire ropes.In order to improve the accuracy of detection of flaws in wire ropes by magnetic flux leakage(MFL),the effect of the distance between a sensor and the surface of a wire rope(i.e.,lift-off) on detection by magnetic flux leakage was in-vestigated.An analysis of the main principles for the choice of lift-off is described by us and a new method that improves the structure of the detector is proposed from the point of view of the design of a magnetic circuit,to restrain the impact of fluctuations of sensor lift-off.The effect of this kind of method is validated by simulation and computation.The results show that the detection sensitivity is markedly increased by this method.Furthermore,the signal-to-noise ratio(SNR) can be increased by over 28%.This method will lend itself to offer reliable scientific information to optimize the structure of excitation devices and improve the accuracy of MFL detection.
基金supported by the National Natural Science Foundation of China under Grant 51991384Anhui Provincial Major Science and Technology Project under Grant 202203c08020010。
文摘High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic performance.In order to solve these problems,a new signal demodulation method is proposed in this paper.The proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter parameters.In addition,a new magnetic polarity detection method is proposed,which is robust to current measurement noise.Finally,experiments verify the effectiveness of the method.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375002 and 62101010)We sincerely thank Beijing Sanse Magnetic Exploration Technology Co.,Ltd.for providing the measurement equipment for the experiment.We also extend our gratitude to Wei Xiao for their valuable writing suggestions.
文摘Magnetic detection is characterized by its non-invasive,rapid,and efficient traits and can be applied in archaeological exploration.This paper presents an aeromagnetic system based on a drone for archaeological exploration,featuring both hardware module integration and data processing methods.The hardware module incorporates a multi-rotor drone,a cesium optically pumped magnetometer,and a synchronized data acquisition system for processing magnetic and GPS position data.It can rapidly measure the magnetic field of the archaeological sites to capture the magnetic anomaly signals.The data processing methods consist of diurnal variation correction,survey line correction,aeromagnetic noise suppression,and a leveling algorithm based on curvelet transform,which is capable of identifying magnetic anomaly signals within the measured magnetic field.Field tests were conducted at the Song Dynasty iron smelting site in Xiacaopu,Anxi County,Fujian Province,China,where the system successfully discovered a new smelting furnace relic,which was subsequently confirmed through excavation.
基金the support of National Natural Science Foundation of China(Grant No.52071215).
文摘A Two-Dimensional Convolutional Neural Network(2D-CNN)-based multi-feature fusion detection method is proposed to improve the detection performance of the submarine wake magnetic anomaly in view of its characteristics of low frequency and low signal-to-noise ratio(SNR).The method involves pre-processing the original signal by using the Savitzky-Golay(S-G)filter,followed by Residual Structure processing to extract the time-domain information,FFT to extract the frequency domain information and Minimum-Entropy Filter(MEF)for noise analysis.The 2D-CNN model with three processing branches is utilised for further feature extraction and signal judgement.To train the method,Simulated target signal dataset is obtained through the submarine wake magnetic anomaly simulation model,and the simulated original signal is acquired by stacking measured noise.The proposed method exhibits great detection performance for signals with different Signal-to-Noise Ratios(SNRs)and various types of noise,achieving a recognition accuracy of 90% for signals with SNRs above-10dB.The theoretical detection range of the submarine has been increased to over 1 km,outperforming similar neural networks based on magnetic dipole models.
基金This work is supported by the National Natural Science Foundation of China[No.41374151]the Sichuan Province Applied Basic Research Project of China[No.2017JY0162]the Young Scholars Development Fund of SWPU[No.201599010079].
文摘To aid the magnetic anomaly detection(MAD)of underground ferromagnetic pipelines,this paper proposes a geometric modeling method based on the magnetic dipole reconstruction method(MDRM).First,the numerical modeling of basic pipe components such as straight sections,bends and elbows,and tee joints are discussed and the relevant mathematical formulations for these components are derived.Next,after analyzing the function of MDRM and various element division strategies,the sectional division and blocked division methods are introduced and applied to the appropriate pipeline components to determine the volume and center coordinates of each element,establishing the general models for the three typical pipeline components considered.The resulting volume and center coordinates of each component are the fundamental parameters for determining the MAD forwarding of underground ferromagnetic pipelines using the MDRM.Finally,based on the combination and transformation of the basic pipeline components considered,the visualized geometric models of typical pipeline layouts including parallel pipelines,pipelines with elbows,and a pipeline with a tee joint are constructed.The results demonstrate the feasibility of the proposed method of geometric modeling for the MDRM,which can be further applied to the finite element modeling of these and other components when analyzing MAD data.Furthermore,the models with output parameters proposed in this paper establish a foundation for the inversion of MAD.
基金supported by the National Natural Science Foundation of China(Nos.61673041,61673041,and 61227902)the National High Technology Research and Development Program 863(No.2014AA123401)
文摘Nuclear magnetic resonance gyroscopes （NMRGs） are a kind of rotation-speed sensor that senses the angular velocity by measuring a frequency shift in the Larmor pre- cession of the nuclear spin in a constant magnetic field.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62175094, 61904067, 61805108, and 62075088)Basic and Applied Basic Research Foundation of Guangdong Province (Grant Nos. 2022A1515011671, 2022A1515010272, and 2020A1515011498)+2 种基金Basic and Applied Basic Research Foundation of Guangzhou (Grant No. 202102020758)Science and Technology R&D Project of Shenzhen (Grant Nos. JSGG20201102163800003, and JSGG20210713091806021)Fundamental Research Funds for the Central Universities (Grant Nos. 21621405, and 21620328)。
文摘Hyperbolic metamaterials(HMMs) are novel artificial materials that excite the surface plasmon resonance(SPR) because of their unique hyperbolic dispersion properties. Herein, to the best of our knowledge, we propose the first HMM-based fiber SPR(HMM-SPR) sensor for vector magnetic detection. By selecting the composite materials and structural parameters of the HMM dispersion management, HMM-SPR sensors can achieve a high refractive index sensitivity of 14.43 μm/RIU. Vector magnetic field detection was performed with the HMM-SPR sensor encapsulated with a magnetic fluid. Compared with other ferrofluidbased magnetic field fiber sensors, the proposed sensor shows pronounced advantages in intensity and direction sensitivity of 1.307 nm/Oe and 7.116 nm/°, respectively. The sensor design approach presented in this paper provides an excellent demonstration of HMM-SPR sensors in various applications.
基金the support of the Fund of State Key Laboratory of Ocean Engineering(GKZD010068,GKZD010074,GKZD010075).
文摘With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typical weak magnetic anomaly target,and their magnetic anomaly detection can only be realized within a certain distance.At present,a towfish or an autonomous underwater vehicle(AUV)is mainly used as the platform to equip magnetometers close to the submarine pipelines for magnetic anomaly detection.However,the mother ship directly affects the towfish,thus causing control interference.The AUV cannot detect in real time,which affects the magnetic anomaly detection and creates problems regarding detection efficiency.Meanwhile,a two-part towed platform has convenient control,thus reducing the interference of the towed mother ship and real-time detection.If the platform can maintain constant altitude sailing through the controller,the data accuracy in the actual magnetic anomaly detection can be guaranteed.On the basis of a two-part towed platform,a magnetic detection system with constant altitude sailing ability for submarine pipelines was constructed in this study.In addition,experimental verification was conducted.The experimental verification research shows that the constant altitude sailing experiment of the two-part towed platform verifies that the platform has good constant altitude sailing ability in both a hydrostatic environment and the actual marine environment.Meanwhile,the offshore magnetic anomaly detection experiment of submarine pipelines verifies the stable measurement function of the magnetic field and the function of the system to detect magnetic anomaly of submarine pipelines.
