This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demons...This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demonstrate real-time visualization of a single 100 nanosecond pulse and discrimination of two pulse trains of different frequencies with a coplanar waveguide and a home-made PCB circuit.This technique finds promising applications in the display of electronic stream and can be used as a pulse discriminator to simultaneously receive and demodulate multiple pulse frequencies.This method of detecting pulse current is expected to provide further detailed analysis of the internal working state of the chip.展开更多
In this paper, an electrical resistance tomography(ERT) imaging method is used as a classifier, and then the Dempster-Shafer's evidence theory with fuzzy clustering is integrated to improve the ERT image quality. ...In this paper, an electrical resistance tomography(ERT) imaging method is used as a classifier, and then the Dempster-Shafer's evidence theory with fuzzy clustering is integrated to improve the ERT image quality. The fuzzy clustering is applied to determining the key mass function, and dealing with the uncertain, incomplete and inconsistent measured imaging data in ERT. The proposed method was applied to images with the same investigated object under eight typical current drive patterns. Experiments were performed on a group of simulations using COMSOL Multiphysics tool and measurements with a piece of porcine lung and a pair of porcine kidneys as test materials. Compared with any single drive pattern, the proposed method can provide images with a spatial resolution of about 10% higher, while the time resolution was almost the same.展开更多
In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transfor...In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transformer(CT)saturation and outliers.In this paper,a current trajectory image-based protection algorithm is proposed for AC lines connected to MMC-HVDC stations using a convolution neural network improved by a channel attention mechanism(CA-CNN).Taking the dual differential currents as two-dimensional coordinates of the moving point,the moving-point trajectories formed by differential currents have significant differences under internal and external faults.Therefore,internal faults can be identified using image recognition based on CA-CNN.This is improved by a channel attention mechanism,data augmentation,and adaptive learning rate.In comparison with other machine learning algorithms,the feature extraction ability and accuracy of CA-CNN are greatly improved.Various fault conditions like different net-work structures,operation modes,fault resistances,outliers,and current transformer saturation,are fully considered to verify the superiority of the proposed protection algorithm.The results confirm that the proposed current trajectory image-based protection algorithm has strong learning and generalizability,and can identify internal faults reliably.展开更多
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electri...We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.展开更多
●In the early 20th century, awakening women who ran from their feudalistic families found that the male-dominated society, where men managed the exterior affairs and women managed the interior ones, was indestructible.
基金Project supported by the National Key R&D Program of China(Grant No.2021YFB2012600)。
文摘This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demonstrate real-time visualization of a single 100 nanosecond pulse and discrimination of two pulse trains of different frequencies with a coplanar waveguide and a home-made PCB circuit.This technique finds promising applications in the display of electronic stream and can be used as a pulse discriminator to simultaneously receive and demodulate multiple pulse frequencies.This method of detecting pulse current is expected to provide further detailed analysis of the internal working state of the chip.
基金Supported by National Natural Science Foundation of China(No.61774014 and No.60772080)
文摘In this paper, an electrical resistance tomography(ERT) imaging method is used as a classifier, and then the Dempster-Shafer's evidence theory with fuzzy clustering is integrated to improve the ERT image quality. The fuzzy clustering is applied to determining the key mass function, and dealing with the uncertain, incomplete and inconsistent measured imaging data in ERT. The proposed method was applied to images with the same investigated object under eight typical current drive patterns. Experiments were performed on a group of simulations using COMSOL Multiphysics tool and measurements with a piece of porcine lung and a pair of porcine kidneys as test materials. Compared with any single drive pattern, the proposed method can provide images with a spatial resolution of about 10% higher, while the time resolution was almost the same.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant 2022JCCXJD01in part by Training Program of Innovation and Entrepreneurship for Undergraduates of China University of Mining and Technology(Beijing)under Grant 202204009.
文摘In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transformer(CT)saturation and outliers.In this paper,a current trajectory image-based protection algorithm is proposed for AC lines connected to MMC-HVDC stations using a convolution neural network improved by a channel attention mechanism(CA-CNN).Taking the dual differential currents as two-dimensional coordinates of the moving point,the moving-point trajectories formed by differential currents have significant differences under internal and external faults.Therefore,internal faults can be identified using image recognition based on CA-CNN.This is improved by a channel attention mechanism,data augmentation,and adaptive learning rate.In comparison with other machine learning algorithms,the feature extraction ability and accuracy of CA-CNN are greatly improved.Various fault conditions like different net-work structures,operation modes,fault resistances,outliers,and current transformer saturation,are fully considered to verify the superiority of the proposed protection algorithm.The results confirm that the proposed current trajectory image-based protection algorithm has strong learning and generalizability,and can identify internal faults reliably.
基金Project supported partly by the National Science Foundation (No.BES-0411898) and the National Institues of Health (No. R01EB00178) USA
文摘We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.
文摘●In the early 20th century, awakening women who ran from their feudalistic families found that the male-dominated society, where men managed the exterior affairs and women managed the interior ones, was indestructible.
