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{"title":"Electron Beam Welding of the HTS Current Lead for the ITER Feeder","authors":"Jianguo Ma;Jia Tao;Zhenfei Liu;Chen Liu;Liming Peng;Wei Wen;Le Yang;Xiaowei Xia;Jiefeng Wu;Rui Wang;Zhihong Liu","doi":"10.1109/TPS.2024.3495636","DOIUrl":"https://doi.org/10.1109/TPS.2024.3495636","url":null,"abstract":"The high-temperature superconducting (HTS) current lead is one of the core components of the International Thermonuclear Experimental Reactor (ITER) magnet feeder system. Due to high-quality requirements, electron beam welding (EBW) was chosen to weld the room temperature terminal, the finned heat exchanger, and the HTS segment. The short mock-up was created to assess the performance of the welded joints. The analysis of macroscopic morphology and microstructure indicates that the welded joint of the short mock-up appeared to be free of visible defects. The tensile strength of the welded samples ranges from 185 to 208 MPa, which is higher than the design requirement of 150 MPa. The side bending test also shows no open discontinuity of the samples. Additionally, the thermal shock test was carried out. The dye penetrant test and the ultrasonic test after thermal shock shows that there are no obvious defects inside or on the surface of the weld seam. Furthermore, the leakage rate of the welded sample measured in the helium tightness leak test was <inline-formula> <tex-math>$2.2times 10^{-10}$ </tex-math></inline-formula>Pa<inline-formula> <tex-math>$cdot $ </tex-math></inline-formula>m3/s, indicating no cracks detected in the joints in the joints. The same parameters were also used for the welding of the long mock-up equipped with fins. The maximum temperature during the welding process does not go over the prescribed limit. The actual HTS current lead was welded, and its performance was evaluated, based on the welding experiments of mock-ups. The welding quality of the HTS current lead was confirmed by all test results.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"52 11","pages":"5451-5456"},"PeriodicalIF":1.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142993770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly Sensitive Detection Ammonia in Water by a Fabry–Perot Interferometer Based on Sparse Sampling and Vernier Effect","authors":"Yitong Li;Yuqiang Yang;Zhihao Huang;Ji Wang;Xiaoguang Mu;Chengyu Mo;Qingjie Lu","doi":"10.1109/JSEN.2024.3502633","DOIUrl":"https://doi.org/10.1109/JSEN.2024.3502633","url":null,"abstract":"For interferometric fiber optic sensors, a method based on sparse sampling to control the sensitivity is proposed and applied to the ammonia measurement in water detected by a Fabry–Perot interferometer (FPI). The designed ammonia sensing interferometer (S-FPI) is fabricated by offset splicing of single-mode optical fibers (SMFs) to form an open cavity, which is filled with ammonia-sensitive oxazine perchlorate (O17). Based on the reaction of O17 with ammonia solution, the refractive index in the cavity is changed, which causes a shift in the interference spectrum of the S-FPI to measure the ammonia concentration. In order to improve the sensitivity of ammonia measurement, the sampling interval of the laser source is controlled to generate the Vernier effect, and the sensitivity of ammonia detection was enhanced by measuring the shift of the sampling-fitted Vernier envelope. Experiments achieved multiple controllable ammonia sensitivities with a maximum sensitivity enhancement of about 16.1 times, verifying the feasibility of this enhanced-sensitivity method. The method does not require the introduction of additional reference interferometer and spectral analyzers, greatly simplifying the sensing system structure. In addition, the sensitivity can be controlled and improved, which has a better application prospect.","PeriodicalId":447,"journal":{"name":"IEEE Sensors Journal","volume":"25 2","pages":"2682-2689"},"PeriodicalIF":4.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142976025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Guest Editorial: Special Issue on Electrical Discharges in Vacuum","authors":"Yasunori Tanaka;Eiji Kaneko;Akiko Kumada;Hiroki Kojima;Yuki Inada;Yasushi Yamano","doi":"10.1109/TPS.2024.3487346","DOIUrl":"https://doi.org/10.1109/TPS.2024.3487346","url":null,"abstract":"","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"52 9","pages":"4362-4364"},"PeriodicalIF":1.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10786897","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142797896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shock Waves of the Electric Field—Part 2: Experimental Studies of Vysikayl’s Jumps and Plasma Nozzles in Plasma With Current","authors":"Philipp I. Vysikaylo","doi":"10.1109/TPS.2024.3505256","DOIUrl":"https://doi.org/10.1109/TPS.2024.3505256","url":null,"abstract":"In our works, we prove that the cumulation (self-focusing) of charged particles in a plasma (with current) is a universal property of cumulative-dissipative structures (CDSs) with characteristic sizes from <inline-formula> <tex-math>$10^{-15}$ </tex-math></inline-formula> to <inline-formula> <tex-math>$10^{27}$ </tex-math></inline-formula> m. The basis of such cumulation is the self-formation of electric field shock waves. Earlier (in Part 1) we proved that the electric field (in a gas-discharge plasma with current) behaves as an additional (to the concentrations of charged particles) component of the plasma. Therefore, both drift profiles and diffusion jumps (sharper discontinuities) should be observed in the plasma, analogs of ordinary Mach shock waves or magnetic field shock waves described by Sagdeev. In electric field shock waves, the pressure is created by the electric field (E) pressure—<inline-formula> <tex-math>$P_{text {E}}sim E^{2}$ </tex-math></inline-formula>/<inline-formula> <tex-math>$8pi $ </tex-math></inline-formula>. Electric field shock waves were first predicted by the author in 1985. The author claims that these standing shock waves focus structures (in a plasma with current) by ambipolar drifts caused by the nonlinearity of the processes of transport of charged particles of the plasma. In this article, we will dwell in detail on the experimental studies of 3-D self-forming plasma cumulative-dissipative Vysikaylo’s structures in gas-discharge plasma. By comparison with experiments, we prove that it is necessary to take into account the violation of electrical neutrality (Poisson’s equation for the electric field) in gas-discharge plasma with current. In this part 2, we will use photographs and double probes to study the self-formation of inhomogeneous 3-D structures (plasmoids) due to the interference of ambipolar drift and gas pumping in inhomogeneous plasma using a local ionizer. For this purpose, we preliminarily locally disturbed the homogeneous plasma in the gas-discharge tube with a beam of fast electrons. This leads to self-formation of local: 1) shock waves of the electric field (a monolayer of positive space charge with jumps of the electric field), stopped by pumping gas (on one side of the fast electron beam); 2) transient 3-D profiles; and 3) Vysikaylo’s plasma nozzles in quasi-neutral homogeneous plasma (on the other side of the beam disturbing the plasma). Based on laboratory experiments and theoretical studies of gas-discharge plasma, we prove that the ambipolar drift caused by different dependences of the electron and positive ion mobility in a simple plasma (with one type of ions) determines the dynamic processes of cumulation (self-focusing) and the formation of 3-D shock waves of the electric field due to the violation of electrical neutrality in electropositive gases.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"52 11","pages":"5306-5314"},"PeriodicalIF":1.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142993602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving Linearity and Symmetry of Synaptic Update Characteristics and Retentivity of Synaptic States of the Domain-Wall Device Through Addition of Edge Notches","authors":"Raman Hissariya;Debanjan Bhowmik","doi":"10.1109/OJNANO.2024.3514900","DOIUrl":"https://doi.org/10.1109/OJNANO.2024.3514900","url":null,"abstract":"Compute-in-memory (CIM) crossbar arrays of non-volatile memory (NVM) synapse devices have been considered very attractive for fast and energy-efficient implementation of various neural network (NN) algorithms. High retention time of the synaptic states and high linearity and symmetry of the synaptic weight update characteristics (long-term potentiation (LTP) and long-term depression (LTD)) are major requirements for the NVM synapses in order to obtain high classification accuracy upon implementation of the NN algorithms on the corresponding crossbar arrays. In this paper, with respect to the spin-orbit-torque-driven domain-wall synapse device, we show that addition of edge notches significantly helps in satisfying the aforementioned requirements. At finite temperatures, notches prevent the domain wall from moving due to stray dipole and thermal fields when SOT-causing current is not applied. This, in turn, improves linearity and asymmetry of the LTP and LTD characteristics of the device as well as the retention time of synaptic states. We have also studied how these synaptic properties depend on the spacing between the notches and the size of the notches in the device. We perform this analysis here through rigorous micromagnetic simulations carried out for room temperature (300K), with dipole and thermal fields taken into account.","PeriodicalId":446,"journal":{"name":"IEEE Open Journal of Nanotechnology","volume":"6 ","pages":"1-9"},"PeriodicalIF":1.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10787236","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Online Excitation Current Pre-Charge Time Adjustment of Output Current Waveform for Pulsed Alternator Based on Backpropagation Neural Network","authors":"Yingjie Chen;Wenchao Li;Youlong Wang;Chen Chen;Qi Li","doi":"10.1109/TPS.2024.3506925","DOIUrl":"https://doi.org/10.1109/TPS.2024.3506925","url":null,"abstract":"In this article, a method based on backpropagation (BP) neural network is proposed to adjust the output current waveform by adjusting the excitation current pre-charge time online. The discharge controller adjusts the output current waveform of the pulsed alternator by automatically modifying the excitation current pre-charge time according to the different current waveform requirements of the load. First, the characteristics of the pulsed alternator in the pulse separate excitation mode are analyzed, and the intrinsic characteristics of the excitation circuit are highlighted. Subsequently, based on the strong nonlinear relationship between different excitation current pre-charge time and their corresponding output pulse waveforms, a BP neural network model is constructed, mapping the output pulse waveform indices to the excitation current pre-charge time. Second, a 3-D field-circuit coupling finite element model of the pulsed alternator is established, and suitable samples for neural network training are collected using this model, facilitating the training of the neural network. Finally, the correctness and effectiveness of the proposed method are verified through experimental research conducted on a prototype platform of the pulsed alternator.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"52 11","pages":"5376-5384"},"PeriodicalIF":1.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142993816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Lorentz-Force MEMS Magnetometer With an Annular Resonance Beam for Z-Axis Sensing","authors":"Junwei Yu;Pingyang Cai;Hengmao Liang","doi":"10.1109/JSEN.2024.3508068","DOIUrl":"https://doi.org/10.1109/JSEN.2024.3508068","url":null,"abstract":"Restricted by the shapes of utilized resonance structures, conventional Lorentz-force micro-electro-mechanical systems (MEMS) magnetometers are rarely designed with the multiturn coil layout for the performance enhancement of Z-axis magnetic sensing by increasing the effective coil length. We put forward a novel Lorentz-force MEMS magnetometer with a low-frequency annular resonance beam for Z-axis sensing. Wherein, four resonance elements are interconnected and coupled into the annular resonance beam with the contraction-expansion (CE) mode (~37.4 kHz), which contributes to generating together Lorentz forces on four sides of the MEMS magnetometer structure. Meanwhile, a three-turn Lorentz force coil with only two coil pads, which is utilized for injecting the alternating current (ac), is located on and electrically insulated with the annular Si resonance beam. Under the Z-axis magnetic field, capacitance comb structures around the annular beam are employed to detect the resonance displacement induced by the Lorentz force. In this article, the proposed MEMS magnetometer is illustrated with device designs, theory analyses, device fabrications, interface circuit realizations, and performance characterizations. Specifically, the designed MEMS magnetometer is fabricated using bulk Si micro-machining processes. In addition, a board-level interface circuit is realized by amplification, phase shift, demodulation, and filtering. By experimental tests, the fabricated MEMS magnetometer has a sensitivity of 214.2 mV/mT with a nonlinearity of 0.42% and a resolution of <inline-formula> <tex-math>$sim 3~mu $ </tex-math></inline-formula>T estimated from noise measurements. Also, it exhibits fine performances on the cross-axis rejection ratios (37 dB), hysteresis (0.34%), and repeatability (~0.9%).","PeriodicalId":447,"journal":{"name":"IEEE Sensors Journal","volume":"25 2","pages":"2502-2509"},"PeriodicalIF":4.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eff-WHAR: A Lightweight Design for Efficient Wearable Sensor-Based Human Activity Recognition","authors":"Zijie Chen;Hailin Zou;Lei Wang;Binbin Wang;Fuchun Zhang;Songjie Ma;Yuanyuan Pan;Jianqing Li","doi":"10.1109/JSEN.2024.3509961","DOIUrl":"https://doi.org/10.1109/JSEN.2024.3509961","url":null,"abstract":"Wearable sensor-based human activity recognition (WHAR) is an important application field that uses sensors for measurement, especially the broad application scenarios in human-computer interaction. Despite the strides made by deep learning-based approaches, practical issues such as deployment on edge devices are often overlooked due to their dependence on massive network layers that require extensive computational and storage resources. This article proposes a novel approach named Eff-WHAR, which aims to improve recognition accuracy and reduce computational burden in the context of WHAR, especially for practical applications on edge devices. The overall approach consists of two parts: multiscale temporal embedding network and channel mixing network. The first part involves utilizing convolution operations with varying receptive fields in the temporal dimension to extract and merge features from the input data. It facilitates a more comprehensive understanding of different behaviors, resulting in enhanced accuracy. In the second part, features are extracted and fused in the sensing channel dimension through a combination of intra-channel and inter-channel convolutions. It is better to reduce computational cost and model size by replacing the traditional 2-D convolution and attention mechanisms, which are commonly used but require a lot of computing power and storage, making them unsuitable for devices with limited resources. We validated Eff-WHAR on eight commonly used WHAR datasets, obtaining outstanding performance compared with SOTA approaches. In addition, we conducted experiments in actual edge devices, verifying the practicality and efficiency of our approach.","PeriodicalId":447,"journal":{"name":"IEEE Sensors Journal","volume":"25 2","pages":"3935-3948"},"PeriodicalIF":4.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142993352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Once-Calibration Brain-Computer Interface to Enhance Convenience for Continuous BCI Interventions in Stroke Patients","authors":"Zuguang Rao;Rui Zhang;Shenghong He;Yajun Zhou;Zilin Lu;Kendi Li;Yuanqing Li","doi":"10.1109/JSEN.2024.3510059","DOIUrl":"https://doi.org/10.1109/JSEN.2024.3510059","url":null,"abstract":"Brain-computer interfaces (BCIs) provide a means of translating neural activity into movement for stroke rehabilitation. Electroencephalography (EEG)-based motor imagery (MI) is a cognitive strategy to enhance motor recovery after stroke. However, traditional MI-BCI systems require extensive calibration before conducting online experiments, thus constraining their practicality. To enhance convenience, we propose a once-calibration strategy (ONCS) that allows each subject to perform only one calibration in continuous BCI interventions over one month. By using supervised and transfer learning to update the model with previous online data, repeated calibrations are eliminated. Furthermore, personalized channel selection (PCS) is designed to reduce the number of channels through the lowest event-related desynchronization (ERD). Compared to the traditional repetitive calibration strategy (RECS), RECS for intra- and inter-subject models, the proposed ONCS for inter-subject (ONCS-inter) models achieve better classification performance using 28 channels. Wherein, the ONCS-inter shows statistically significant improvements (<inline-formula> <tex-math>${p} lt 0.05$ </tex-math></inline-formula>, one-tailed test). When using PCS for channel selection, ONCS-inter outperforms ONCS for intra-subject (ONCS-intra) (<inline-formula> <tex-math>${p} lt 0.01$ </tex-math></inline-formula>, for 16, <inline-formula> <tex-math>${18}, ldots, {28}$ </tex-math></inline-formula> channels, two-tailed test) and surpasses RECS (<inline-formula> <tex-math>${p} lt 0.05$ </tex-math></inline-formula> for all channels, two-tailed test). Remarkably, ONCS-inter exceeds the best results achieved with traditional RECS, even with only two channels. Extensive comparison and ablation studies demonstrate the effectiveness of our proposed ONCS combined with inter-subject models and a few channels in maintaining classification accuracy. The proposed ONCS with PCS holds promise for enhancing the convenience of continuous BCI interventions within one month for stroke patients.","PeriodicalId":447,"journal":{"name":"IEEE Sensors Journal","volume":"25 2","pages":"3949-3963"},"PeriodicalIF":4.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142993350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wasserstein-Adaptive-Consensus-Based Resilient Distributed H∞ Filtering in Wireless Sensor Networks With Cyberattacks","authors":"Yanshen Gao;Hongbo Zhu;Tan Wang","doi":"10.1109/JSEN.2024.3508758","DOIUrl":"https://doi.org/10.1109/JSEN.2024.3508758","url":null,"abstract":"This article addresses the distributed state estimation problem in wireless sensor networks (WSNs) under potential threats from malicious cyberattacks. A distributed H<inline-formula> <tex-math>$_{infty }$ </tex-math></inline-formula> filtering (DHF) approach based on Wasserstein adaptive consensus is proposed to enhance estimation accuracy and resilience against such cyberattacks. First, each sensor gathers partial measurement information and updates the local prior estimate of the system by performing Krein space H<inline-formula> <tex-math>$_{infty }$ </tex-math></inline-formula> optimal filtering, followed by information exchange between neighboring sensors. Second, after obtaining local posterior estimates from neighboring sensors, a Wasserstein classification mechanism is established from the perspective of probability distribution to filter out the distributions of the state estimates from attacked sensor nodes, effectively discarding the compromised estimates. Third, an adaptive consensus scheme is designed to update the fused distribution of the state estimate for each sensor node, aiming to achieve consistent state estimation with low communication burden, which calculates the adaptive combination weights for the distributions of the state estimates from unattacked sensor nodes. Finally, the prior estimate for the next time step is predicted based on the local fused estimate at the current time step. The effectiveness of the proposed method is demonstrated by conducting simulations on specific instances of mobile target localization under various cyberattack scenarios.","PeriodicalId":447,"journal":{"name":"IEEE Sensors Journal","volume":"25 2","pages":"3649-3658"},"PeriodicalIF":4.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}