Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli.However,their applications are limited by challenges in terms of issues in biocom...Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli.However,their applications are limited by challenges in terms of issues in biocompatibility,custom shape,and self-healing.Herein,a conductive,stretchable,adaptable,self-healing,and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol(PVA)with sodium tetraborate.The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion.Significantly,owing to the magnetic constituent,the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation.The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions.Additionally,the multifunctional hydrogel displays absorption-dominated electromagnetic interference(EMI)shielding properties.The total shielding performance of the composite hydrogel increases to~62.5 dB from~31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm.The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.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
Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to...Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.展开更多
Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation...Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.展开更多
In this paper, the current distribution in a 300-W-class PEMFC stack was investigated in order to determine the operating state of the stack. Measurements of the magnetic field were performed on several cells in the s...In this paper, the current distribution in a 300-W-class PEMFC stack was investigated in order to determine the operating state of the stack. Measurements of the magnetic field were performed on several cells in the stack. The vector of the magnetic field expressed the direction of the macroscopic current, which was from the anode side to the cathode side. This direction matched the polarity of the stack. In the measurement results, current distributions differed among cells;each cell had a different performance. Furthermore, we have tried to evaluate faults, such as flooding, by measuring the magnetic field and variations in the voltage.展开更多
We report a p24(HIV disease biomarker)detection assay using an MgO-based magnetic tunnel junction(MTJ)sensor and 20-nm magnetic nanoparticles.The MTJ array sensor with sensing area of 890×890μ2 possessing a sens...We report a p24(HIV disease biomarker)detection assay using an MgO-based magnetic tunnel junction(MTJ)sensor and 20-nm magnetic nanoparticles.The MTJ array sensor with sensing area of 890×890μ2 possessing a sensitivity of 1.39%/Oe was used to detect p24 antigens.It is demonstrated that the p24 antigens could be detected at a concentration of 0.01μg/ml.The development of bio-detection systems based on magnetic tunnel junction sensors with high-sensitivity will greatly benefit the early diagnosis of HIV.展开更多
The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryo...The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryogenic field and magnetic field. The response to a temperature and strain change of coated-soft polymeric FBGs is tested by comparing with those of coated-metal FBGs. The results indicate that the coated-soft polymeric FBGs can freely detect temperature and thermal strain, their At variable magnetic field, the tested results indicate accuracy and repeatability are also discussed in detail. that the cross-coupling effects of FBGs with different matrixes are not negligible to measure electromagnetic strain during fast excitation. The present results are expected to be able to provide basis measurements on the strain of pulsed superconducting magnet/cable (cable- around-conduit conductors, cable-in-conduit conductors), independently or utilized together with other strain measurement methods.展开更多
A novel classification algorithm based on abnormal magnetic signals is proposed for ground moving targets which are made of ferromagnetic material. According to the effect of diverse targets on earth's magnetism,t...A novel classification algorithm based on abnormal magnetic signals is proposed for ground moving targets which are made of ferromagnetic material. According to the effect of diverse targets on earth's magnetism,the moving targets are detected by a magnetic sensor and classified with a simple computation method. The detection sensor is used for collecting a disturbance signal of earth magnetic field from an undetermined target. An optimum category match pattern of target signature is tested by training some statistical samples and designing a classification machine. Three ordinary targets are researched in the paper. The experimental results show that the algorithm has a low computation cost and a better sorting accuracy. This classification method can be applied to ground reconnaissance and target intrusion detection.展开更多
The magnetic improvised explosive devices (IEDs), also commonly known as a type of a sticky bomb, is simply constructed devices yet very lethal. This paper puts forward the idea of an electronic compass that is capa...The magnetic improvised explosive devices (IEDs), also commonly known as a type of a sticky bomb, is simply constructed devices yet very lethal. This paper puts forward the idea of an electronic compass that is capable of sensing the change of a magnetic field generated by a magnet and translating it into interpretable data, which could act as the base for the further studies and assist in developing a greener automated system for detecting this device. The electronic compass is specifically chosen for reducing power consumption of systems in addition to the fact that it is available at a low cost.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
For the purpose of motor fault real-time monitoring, this research developed a nano-silicon ni- tride film based magnetic field (MF) sensor, and applied this sensor in MF detection of two common faults. Through experi...For the purpose of motor fault real-time monitoring, this research developed a nano-silicon ni- tride film based magnetic field (MF) sensor, and applied this sensor in MF detection of two common faults. Through experiment, it turned out that arc discharge and slot discharge occur in motor fault produce MF with certain laws. This result proved the feasibility of the sensor and sensing method in MF analysis, and revealed possibility of a new method in fault detection.展开更多
The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber link...The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulatein the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity .The sensor system exhibited a noise-equivalent field of 8 pT/√Hz and a 3 dB bandwidth of ~10 MHz.展开更多
MEMS swallowable capsule is a novel technology in the non-invasive surgery. This technology provides a way to diagnose directly into the deep intestinal where the traditional invasive technology implemented, such as X...MEMS swallowable capsule is a novel technology in the non-invasive surgery. This technology provides a way to diagnose directly into the deep intestinal where the traditional invasive technology implemented, such as X-Ray, endoscopy. It is a key for us to locate and track the position of a MEMS capsule in clinical applications. To solve this problem, we implemented a magnetic sensor module based on the scalar form of the magnetic dipole model,which was designed with very small size (5.2*2.1*1.2 cm) and easy to assemble to satisfy the system requirement. Here we discuss in detail the principle of magnetic dipole model, rules of selecting sensor and functions of the module. Some trials are established to test the characteristic of the module. The results of the Cm experiment demonstrates that the module follows the rules of the new magnetic dipole model form.展开更多
We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary curre...We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.展开更多
This paper focuses on the key issues of information processing in the new sensing technology-electromagnetic induction tomography and depth theoretical study and experimental simulation have been conducted.In this stu...This paper focuses on the key issues of information processing in the new sensing technology-electromagnetic induction tomography and depth theoretical study and experimental simulation have been conducted.In this study,Labview is used to drive the data acquisition card to control the signal generation and acquisition,and Matlab is used to achieve algorithms such as Fast Fourier Transformation (FFT) algorithm,relevant law algorithm and the classical method algorithm.The simulation results show this software system enables successful digital phase identification and the phase difference resolution of 0.10 can be achieved,which is consistent with theoretical analysis.It can also be seen that software system based on Labview and Matlab is a successful method to identify the phase difference in magnetic induction tomography system,which can meet the measurement needs of sensor nodes,laying the basis for the further development of medical IoT study.展开更多
Fibre-optic magnetic sensors with magnetostrictive films are used as all-fibre Mach-Zehnder interferometer to detect the optical phase shift,which is caused by the magnetostriction-induced strains transferred from the...Fibre-optic magnetic sensors with magnetostrictive films are used as all-fibre Mach-Zehnder interferometer to detect the optical phase shift,which is caused by the magnetostriction-induced strains transferred from the magnetostrictive film to the fibre.A theoretical model based on the plane strain approximation and uniform axial strain is developed to determine the magneto-mechano-optical transfer relations in this kind of sensors.The expression for the model is presented as well as relation of the phase shift in the fibre to the magnetic and elastic properties of the magnetostrictive film coated on the fibre.And from the model,the thickness of the film has significant influence on the phase shift.展开更多
Increasing use of silver in various fields has caused Ag^(+)pollution in water environment,taking great threats to people’s health.As a consequence,establishing rapid and reliable methods for sensitive determination ...Increasing use of silver in various fields has caused Ag^(+)pollution in water environment,taking great threats to people’s health.As a consequence,establishing rapid and reliable methods for sensitive determination of Ag^(+)is of great significance.Fluorescent(FL)sensors based on carbon dots(CDs),an excellent carbonaceous nanomaterial with strong and stable fluorescence,have absorbed extensive attentions in analysis of pollutants due to its advantages of carbon sources being readily available,low cost,easy operation and fast response.Moreover,ion-imprinting is a better way to increase the selectivity of the proposed method.Present work described an effective method for the sensitive measurement of silver ion in water samples in combination with magnetic ion-imprinted solid phase extraction and CDs based fluorescent sensor,which took full advantages of easy separation and high enrichment of magnetic solid phase extraction,high selectivity of ion-imprinting technology,and sensitivity and rapid response of fluorescent sensor from CDs.Sulfur-doped CDs derived from dithizone and magnetic ion-imprinted nanomaterial were prepared,and characterized with Fourier transform infrared spectroscopy and transmission electron microscope,etc.Magnetic Ag^(+)imprinted nanomaterial based solid phase extraction was employed for separating and enriching Ag^(+)from water samples.The significant parameters were optimized in detail.Under the optimal conditions,the proposed method provided good linearity in the range of 0.01-0.4μmol/L and low detection limit of 3 nmol/L.The reliability of the proposed method was validated with real water samples,and the results demonstrated that the proposed method was simple,robust,selective and sensitive detection tool for Ag^(+)in real water samples.展开更多
The ultra-low-frequency (ULF) electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake (EQ) prediction. This paper reviews previous convincing evidence on t...The ultra-low-frequency (ULF) electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake (EQ) prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before three major EQs. Then, we present further statistical study on the ULF occurrence, our networks of ULF monitoring in different spatial scales in Japan and finally we present several signal processings to identify the seismogenic emissions by showing latest results for recent large EQs.展开更多
With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this pape...With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage (MFL) in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.展开更多
基金the financial supports from the National Natural Science Foundation of China(52231007,51725101,11727807,22088101,52271167)the Shanghai Excellent Academic/Technological Leaders Program(19XD1400400)+4 种基金the Ministry of Science and Technology of China(973 Project Nos.2018YFA0209100 and 2021YFA1200600)the Fundamental Research Funds for the Central Universities(2022JCCXHH09)the Foundation for University Youth Key Teachers of Henan Province(2020GGJS170)the Support Program for Scientific and Technological Innovation Talents of Higher Education in Henan Province(21HASTIT004)Key Research Project of Zhejiang Lab(No.2021PE0AC02)。
文摘Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli.However,their applications are limited by challenges in terms of issues in biocompatibility,custom shape,and self-healing.Herein,a conductive,stretchable,adaptable,self-healing,and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol(PVA)with sodium tetraborate.The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion.Significantly,owing to the magnetic constituent,the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation.The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions.Additionally,the multifunctional hydrogel displays absorption-dominated electromagnetic interference(EMI)shielding properties.The total shielding performance of the composite hydrogel increases to~62.5 dB from~31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm.The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.
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This paper is supported by the National "863" Program in the Tenth Five-Year-Plan (No. 2002AA615020)Eleventh Five-Year-Plan (No. 2006AA09A201)the Focused Subject Program of Beijing (No. XK104910598).
文摘Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.
基金the financial support from Canada Innovation Fund-Leaders Opportunity Fundthe Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.
文摘In this paper, the current distribution in a 300-W-class PEMFC stack was investigated in order to determine the operating state of the stack. Measurements of the magnetic field were performed on several cells in the stack. The vector of the magnetic field expressed the direction of the macroscopic current, which was from the anode side to the cathode side. This direction matched the polarity of the stack. In the measurement results, current distributions differed among cells;each cell had a different performance. Furthermore, we have tried to evaluate faults, such as flooding, by measuring the magnetic field and variations in the voltage.
基金President’s Fund of CUHKSZ,Longgang Key Laboratory of Applied Spintronics,at The Chinese University of Hong Kong,the National Natural Science Foundation of China(Grant Nos.11974298 and 61961136006)the Shenzhen Fundamental Research Fund,China(Grant No.JCYJ20170410171958839)Shenzhen Peacock Group Plan,China(Grant No.KQTD20180413181702403).
文摘We report a p24(HIV disease biomarker)detection assay using an MgO-based magnetic tunnel junction(MTJ)sensor and 20-nm magnetic nanoparticles.The MTJ array sensor with sensing area of 890×890μ2 possessing a sensitivity of 1.39%/Oe was used to detect p24 antigens.It is demonstrated that the p24 antigens could be detected at a concentration of 0.01μg/ml.The development of bio-detection systems based on magnetic tunnel junction sensors with high-sensitivity will greatly benefit the early diagnosis of HIV.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11302225,11121202 and 11327802the National Key Project of Magneto-Constrained Fusion Energy Development Program under Grant No 2013GB110002the Postdoctoral Science Foundation of China under Grant No 2014M560820
文摘The strain and temperature sensing performance of fiber-optic Bragg gratings (FBGs) with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryogenic field and magnetic field. The response to a temperature and strain change of coated-soft polymeric FBGs is tested by comparing with those of coated-metal FBGs. The results indicate that the coated-soft polymeric FBGs can freely detect temperature and thermal strain, their At variable magnetic field, the tested results indicate accuracy and repeatability are also discussed in detail. that the cross-coupling effects of FBGs with different matrixes are not negligible to measure electromagnetic strain during fast excitation. The present results are expected to be able to provide basis measurements on the strain of pulsed superconducting magnet/cable (cable- around-conduit conductors, cable-in-conduit conductors), independently or utilized together with other strain measurement methods.
基金Sponsored by the National Natural Science Foundation of China (60773129)the Excellent Youth Science and Technology Foundation of Anhui Province of China ( 08040106808)
文摘A novel classification algorithm based on abnormal magnetic signals is proposed for ground moving targets which are made of ferromagnetic material. According to the effect of diverse targets on earth's magnetism,the moving targets are detected by a magnetic sensor and classified with a simple computation method. The detection sensor is used for collecting a disturbance signal of earth magnetic field from an undetermined target. An optimum category match pattern of target signature is tested by training some statistical samples and designing a classification machine. Three ordinary targets are researched in the paper. The experimental results show that the algorithm has a low computation cost and a better sorting accuracy. This classification method can be applied to ground reconnaissance and target intrusion detection.
基金supported by the Malaysia Ministry of Higher Education under FRGS Grant No.6071306
文摘The magnetic improvised explosive devices (IEDs), also commonly known as a type of a sticky bomb, is simply constructed devices yet very lethal. This paper puts forward the idea of an electronic compass that is capable of sensing the change of a magnetic field generated by a magnet and translating it into interpretable data, which could act as the base for the further studies and assist in developing a greener automated system for detecting this device. The electronic compass is specifically chosen for reducing power consumption of systems in addition to the fact that it is available at a low cost.
基金Sup.ported by the High TechnologyResearch and Development Programme of China (No.2006AA04Z368), the National Natural Science Foundation of China (No. 30900320, 30570485) and Innovation Program of Shanghai Municipal Education Commission (No. 10YZ93).
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For the purpose of motor fault real-time monitoring, this research developed a nano-silicon ni- tride film based magnetic field (MF) sensor, and applied this sensor in MF detection of two common faults. Through experiment, it turned out that arc discharge and slot discharge occur in motor fault produce MF with certain laws. This result proved the feasibility of the sensor and sensing method in MF analysis, and revealed possibility of a new method in fault detection.
文摘The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulatein the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity .The sensor system exhibited a noise-equivalent field of 8 pT/√Hz and a 3 dB bandwidth of ~10 MHz.
文摘MEMS swallowable capsule is a novel technology in the non-invasive surgery. This technology provides a way to diagnose directly into the deep intestinal where the traditional invasive technology implemented, such as X-Ray, endoscopy. It is a key for us to locate and track the position of a MEMS capsule in clinical applications. To solve this problem, we implemented a magnetic sensor module based on the scalar form of the magnetic dipole model,which was designed with very small size (5.2*2.1*1.2 cm) and easy to assemble to satisfy the system requirement. Here we discuss in detail the principle of magnetic dipole model, rules of selecting sensor and functions of the module. Some trials are established to test the characteristic of the module. The results of the Cm experiment demonstrates that the module follows the rules of the new magnetic dipole model form.
文摘We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.
文摘This paper focuses on the key issues of information processing in the new sensing technology-electromagnetic induction tomography and depth theoretical study and experimental simulation have been conducted.In this study,Labview is used to drive the data acquisition card to control the signal generation and acquisition,and Matlab is used to achieve algorithms such as Fast Fourier Transformation (FFT) algorithm,relevant law algorithm and the classical method algorithm.The simulation results show this software system enables successful digital phase identification and the phase difference resolution of 0.10 can be achieved,which is consistent with theoretical analysis.It can also be seen that software system based on Labview and Matlab is a successful method to identify the phase difference in magnetic induction tomography system,which can meet the measurement needs of sensor nodes,laying the basis for the further development of medical IoT study.
文摘Fibre-optic magnetic sensors with magnetostrictive films are used as all-fibre Mach-Zehnder interferometer to detect the optical phase shift,which is caused by the magnetostriction-induced strains transferred from the magnetostrictive film to the fibre.A theoretical model based on the plane strain approximation and uniform axial strain is developed to determine the magneto-mechano-optical transfer relations in this kind of sensors.The expression for the model is presented as well as relation of the phase shift in the fibre to the magnetic and elastic properties of the magnetostrictive film coated on the fibre.And from the model,the thickness of the film has significant influence on the phase shift.
基金supported by the National Natural Science Foundation of China(No.21976211).
文摘Increasing use of silver in various fields has caused Ag^(+)pollution in water environment,taking great threats to people’s health.As a consequence,establishing rapid and reliable methods for sensitive determination of Ag^(+)is of great significance.Fluorescent(FL)sensors based on carbon dots(CDs),an excellent carbonaceous nanomaterial with strong and stable fluorescence,have absorbed extensive attentions in analysis of pollutants due to its advantages of carbon sources being readily available,low cost,easy operation and fast response.Moreover,ion-imprinting is a better way to increase the selectivity of the proposed method.Present work described an effective method for the sensitive measurement of silver ion in water samples in combination with magnetic ion-imprinted solid phase extraction and CDs based fluorescent sensor,which took full advantages of easy separation and high enrichment of magnetic solid phase extraction,high selectivity of ion-imprinting technology,and sensitivity and rapid response of fluorescent sensor from CDs.Sulfur-doped CDs derived from dithizone and magnetic ion-imprinted nanomaterial were prepared,and characterized with Fourier transform infrared spectroscopy and transmission electron microscope,etc.Magnetic Ag^(+)imprinted nanomaterial based solid phase extraction was employed for separating and enriching Ag^(+)from water samples.The significant parameters were optimized in detail.Under the optimal conditions,the proposed method provided good linearity in the range of 0.01-0.4μmol/L and low detection limit of 3 nmol/L.The reliability of the proposed method was validated with real water samples,and the results demonstrated that the proposed method was simple,robust,selective and sensitive detection tool for Ag^(+)in real water samples.
基金A considerable part of the works was carried out in the frameworks of Frontier Projects by NASDA and RIKENNICT(National Institute of Information and Communications Technology) (R and D promotion scheme funding international joint research) for its financial support
文摘The ultra-low-frequency (ULF) electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake (EQ) prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before three major EQs. Then, we present further statistical study on the ULF occurrence, our networks of ULF monitoring in different spatial scales in Japan and finally we present several signal processings to identify the seismogenic emissions by showing latest results for recent large EQs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61273164 and 61034005)the National High Technology Research and Development Program of China (Grant No. 2012AA040104)the Fundamental Research Funds for the Central Universities, China (Grant No. N100104102)
文摘With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage (MFL) in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.