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Perpendicularly assembled oriented electrospinning nanofibers based piezoresistive pressure sensor with wide measurement range

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Nano Research 2024年第7期17卷 6493-6501页

作者： Xiaoxue Bi Zhigang Duan Xiaojuan Hou Shuo Qian Mengjiao Yuan Jiajun Hu Jie Zhang Yuchen Lu Yanli Liu Jian He Zhiling Peng Xiujian Chou School of Mechanical and Electrical Engineering North University of ChinaTaiyuan 030051China Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan 030051China School of Software North University of ChinaTaiyuan 030051China School of Information and Communication Engineering North University of ChinaTaiyuan 030051China

With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent ***,it is a challenge to achieve a sensor with high sensitivity,wide measurement range,and wearing ***,we develop an oriented electrospinning thermoplastic polyurethane/polyacrylonitrile(TPU/PAN)nanofibers(OETPN)based piezoresistive pressure sensor(PONPS)in which the active layer and the electrode are assembled *** interdigital electrode is fabricated by spraying silver nanowires(AgNWs)on the OETPN through a mask *** active layer is composed of OETPN coated with MXene,encapsulated on the electrode by polyurethane(PU)*** porous structure of nanofibers membrane broadens the measurement range of the *** oriented nanofibers as active layer can improve the sensitivity in low pressure,because oriented nanofibers without interweaving nanofibers are more compressible than disordered *** prepared using the spraying method creates nanoscale microstructure and increases *** perpendicular assembly has greater response between the active layer and the electrode than the parallel assembly to improve the *** sensor exhibits high sensitivity(6.71 kPa^(−1),0.02–2 kPa)and wide measurement range(0.02–700 kPa).The sensor can detect weak signals such as radial artery.A pressure array constructed precisely represents the distribution of *** intelligent throat is created by combining machine learning algorithms with the *** can detect and recognize subtle throat vibrations while speaking,achieving recognition accuracy up to 100%using support vector machine(SVM)for five words with different *** fabricated sensor shows promising prospects in personal healthcare and intelligent robots.

关键词： oriented nanofibers perpendicular assembly parallel assembly intelligent throat machine learning algorithms

Toward a fundamental understanding of the heterogeneous multiphysics behaviors of silicon monoxide/graphite composite anodes

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Carbon Energy 2024年第1期6卷 142-158页

作者： Xiang Gao Suli Li Jiachen Xue Dianyang Hu Jun Xu Department of Mechanical Engineering and Engineering Science University of North Carolina at CharlotteCharlotteNorth CarolinaUSA Vehicle Energy and Safety Laboratory(VESL) Battery ComplexityAutonomous Vehicleand Electrification(BATT CAVE)Research CenterUniversity of North Carolina at CharlotteCharlotteNorth CarolinaUSA Zhuhai CosMX Battery Co.Ltd. ZhuhaiGuangdongChina School of Data Science University of North Carolina at CharlotteCharlotteNorth CarolinaUSA

Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion *** major bottleneck for SiO/Gr composite anode is the poor cyclability arising from the stress/strain behaviors due to the mismatch between two heterogenous materials during the lithiation/delithiation *** date,a meticulous and quantitative understanding of the highly nonlinear coupling behaviors of such materials is still ***,an electro–chemo–mechanics-coupled detailed model containing particle geometries is *** underlying mechanism of the regulation between SiO and Gr components during electrochemical cycling is quantitatively *** discover that increasing the SiO weight percentage(wt%)reduces the utilization efficiency of the active materials at the same 1C rate charging and enhances the hindering effects of stress-driven flux on *** addition,the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of *** study provides new insights into the fundamental interactions between SiO and Gr materials and advances the investigation methodology for the design and evaluation of next-generation high-energydensity batteries.

关键词： interactions lithium-ion batteries mechanical constraint multiphysics modeling Si-based anode

A high-performance electromagnetic energy harvester for scavenging ultra-low frequency vibration energy of human foot movement

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Science China(Technological Sciences) 2024年第5期67卷 1391-1400页

作者： HU JiaJun QIAN Shuo WU Hui HU DongXu NIU LiXin BI XiaoXue ZHANG Jie HOU XiaoJuan GENG WenPing MU JiLiang HE Jian CHOU XiuJian Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan030051China School of Software North University of ChinaTaiyuan030051China

In our daily lives,low-frequency kinetic energy primarily manifests as ***,effective harnessing of lowfrequency kinetic energy remains a formidable *** paper proposes a rope-driven rotor that rotates around an axis and consists of an ultra-high-molecular-weight polyethylene(UHMWPE)wire wrapped around a metal *** rotor can convert ultra-low frequency vibration/linear motion into rapid rotation by pressing the top at low frequencies and driving the rope for a quick *** harvester can generate up to 36.25 m W power using a 0.1-mm-diameter UHMWPE wire as the rotor when periodically pressed down to 20 mm at a frequency of 1 Hz.A simple power generation floor is assembled,generating 28.58-m W power with a matching load at a frequency of 1.5 ***,the harvester can increase the charging voltage of a 0.47-F supercapacitor from 0 to 6.8 V within 10 *** addition,the harvester can harvest energy through a light finger press motion,and the energy obtained can also support the continuous operation of multiple electronic devices *** study introduces an effective method for harvesting ultra-low frequency energy and has great prospects in the field of power generation floor and human movement energy harvesting.

关键词： electromagnetic energy harvester rope-shaft coupling structure human motion ultra-low frequency

Flexible multilayer MEMS coils and their application in energy harvesters

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Science China(Technological Sciences) 2024年第4期67卷 1282-1293页

作者： ZHANG Jie HOU XiaoJuan QIAN Shuo BI XiaoXue HU DongXu LIU JianJun GENG WenPing MU JiLiang HE Jian CHOU XiuJian Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan 030051China School of Software North University of ChinaTaiyuan 030051China

Electromagnetic vibration energy harvesters are promising for the power supply of wireless sensor nodes,small electronic devices,and wearable *** electromagnetic harvesters usually increase output by increasing the size of coils and magnets,limiting the improvement of energy conversion efficiency and power *** this study,multilayer microelectromechanical system(MEMS)coils were prepared using flexible electronics,and their high integration performance in arbitrary space was utilized to greatly improve the utilization of the space magnetic field by the electromagnetic *** core magnet of the generator was magnetically balanced to achieve levitation,which improved the sensitivity and reduced fatigue damage compared with traditional spring *** wound coils on the top and bottom of the magnet and the flexible coils on the sides worked together to improve the energy efficiency and output of the *** output performance of the device with different number distributions was simulated using mathematical models to obtain the optimal structural *** results show that by introducing flexible multilayer MEMS coils on the side surface of the energy harvester,the open-circuit voltage of the energy generators increased from 7 to 10 V by more than 43%.Flexible multilayer MEMS coils can enhance energy conversion rates and possess compact dimensions,making them suitable for integration onto complex *** the vibration energy harvesting system testing,the maximum peak power of the harvester was 7.1 m W at an acceleration of1 g and a resonant frequency of 11 Hz with a resistor of 3.5 kΩinternal ***,a 470μF capacitor can be charged to 3.5 V within 10 s to drive a hygrothermograph to work for more than 80 s and can supply a light bulb *** strategy shows the great potential of vibration-energy-driven electromagnetic generators for powering small electronics in limited spaces.

关键词： electromagnetic harvester mechanical energy harvesting multilayer MEMS coils magnetic levitation overall space magnetic field flexible planar coils

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu Liu Chongru Liu north China Electric Power university Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC ***,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC ***,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is ***,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind *** simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed

Density functional theory study of B- and Si-doped carbons and their adsorption interactions with sulfur compounds

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Carbon Energy 2024年第2期6卷 195-208页

作者： Peng Guo Hong Zhang Shuliang Dong Libao An College of Mechanical Engineering North China University of Science and TechnologyTangshanHebeiChina College of Life Sciences North China University of Science and TechnologyTangshanHebeiChina

Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion *** this paper,properties of intrinsic B or Si single-atom doped,and B-Si codoped graphene(GR)and graphdiyne(GDY)were investigated by using density functional theory-based calculations,in which the optimal doping configurations were explored for potential applications in adsorbing sulfur *** showed that both B or Si single-atom doping and B-Si codoping could substantially enhance the electron transport properties of GR and GDY,improving their surface ***,B and Si atoms displayed synergistic effects for the codoped configurations,where B-Si codoped GR/GDY exhibited much better performance in the adsorption of sulfurcontaining chemicals than single-atom doped *** addition,results demonstrated that,after B-Si codoping,the adsorption energy and charge transfer amounts of GDY with sulfur compounds were much larger than those of GR,indicating that B-Si codoped GDY might be a favorable material for more effectively interacting with sulfur reagents.

关键词： adsorption density functional theory doping graphdiyne graphene sulfur compounds

Complementary-Label Adversarial Domain Adaptation Fault Diagnosis Network under Time-Varying Rotational Speed and Weakly-Supervised Conditions

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Computers, Materials & Continua 2024年第4期79卷 761-777页

作者： Siyuan Liu Jinying Huang Jiancheng Ma Licheng Jing Yuxuan Wang School of Data Science and Technology North University of ChinaTaiyuan030051China School of Mechanical Engineering North University of ChinaTaiyuan030051China

Recent research in cross-domain intelligence fault diagnosis of machinery still has some problems,such as relatively ideal speed conditions and sample *** engineering practice,the rotational speed of the machine is often transient and time-varying,which makes the sample annotation increasingly ***,the number of samples collected from different health states is often *** deal with the above challenges,a complementary-label(CL)adversarial domain adaptation fault diagnosis network(CLADAN)is proposed under time-varying rotational speed and weakly-supervised *** the weakly supervised learning condition,machine prior information is used for sample annotation via cost-friendly complementary label learning.A diagnosticmodel learning strategywith discretized category probabilities is designed to avoidmulti-peak distribution of prediction *** adversarial training process,we developed virtual adversarial regularization(VAR)strategy,which further enhances the robustness of the model by adding adversarial perturbations in the target *** experiments on two case studies validated the superior performance of the proposed method.

关键词： Time-varying rotational speed weakly-supervised fault diagnosis domain adaptation

ZIF-8-functionalized polymer electrolyte with enhanced performance for high-temperature solid-state lithium metal batteries

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Rare Metals 2024年第3期43卷 984-994页

作者： Jin-Fang Zhang Yuan-Yuan Wang Xiao-Feng Li Gen-Yan Zhang Ying Li Rong Liu Sheng-Liang Hu Tuo-Ping Hu Ruth Knibbe Qing-Bing Xia School of Materials Science and Engineering North University of ChinaTaiyuan030051China School of Energy and Power Engineering North University of ChinaTaiyuan030051China School of Chemistry and Chemical Engineering North University of ChinaTaiyuan030051China School of Mechanical and Mining Engineering The University of QueenslandBrisbaneQLD4072Australia

Solid polymer electrolytes(SPEs)with high ionic conductivity are desirable for solid-state lithium metal batteries(SSLMBs)to achieve enhanced safety and energy *** nanofillers into a polymeric matrix to develop nanocomposite solid electrolytes(NCSEs)has become a promising method for improving the ionic conductivity of the ***,a novel ZIF-8-functionalized NCSE was prepared for high-temperature S SLMB s using an in situ radical polymerization *** is found that the ZIF-8 nanoparticles could reduce the crystallinity of polymer segments and offer a Lewis acid surface that promotes the dissociation of lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)and stabilizes the TFSI^(-) anion ***,the as-prepared NCSE exhibits an outstanding ionic conductivity of 1.63×10^(-3)S·cm^(-1),an electrochem ical stability window of 5.0 V at 80℃,and excellent interface compatibility with lithium metal anode with a stable polarization over 2000 ***,the assembled SSLMBs with LiFePO_(4)cathode show dendrite-free Li-metal surface,good rate capability,and stable cycling stability with a capacity retention of 70%over 1000 cycles at a high temperature of 80℃.This work provides valuable insights into promoting the ionic conductivity of SPEs.

关键词： Lithium metal batteries Metal-organic frameworks Solid polymer electrolytes Lithium metal anode Interfacial compatibility

Quantum block coherence with respect to projective measurements

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Chinese Physics B 2024年第8期33卷 213-220页

作者：王璞李忠艳孟会贤 School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China

Quantum coherence serves as a defining characteristic of quantum mechanics,finding extensive applications in quantum computing and quantum communication *** study explores quantum block coherence in the context of projective measurements,focusing on the quantification of such ***,we define the correlation function between the two general projective measurements P and Q,and analyze the connection between sets of block incoherent states related to two compatible projective measurements P and ***,we discuss the measure of quantum block coherence with respect to projective *** on a given measure of quantum block coherence,we characterize the existence of maximal block coherent states through projective *** research integrates the compatibility of projective measurements with the framework of quantum block coherence,contributing to the advancement of block coherence measurement theory.

关键词： quantum coherence compatibility projective measurement quantum block coherence