检索结果-南通市图书馆

The rate dependence of the dielectric strength of dielectric elastomers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2024年第1期15卷 110-126页

作者： Xianghe Zheng Jianyou Zhou Pan Jia Zheng Zhong School of science Harbin Institute of TechnologyShenzhenChina

Elastomers are widely used in electronics and electrical devices,either as insulators or *** insulation and actuation performance of elastomers are highly suscepti-ble to their dielectric *** the factors that influ-encethedielectricstrength ofelastomers,material viscoelasticity is an important factor that needs further *** the material viscoelasticity is often character-ized by rate-dependent behaviors,we present two different sample configurations to experimentally examine the electrical and mechanical rate dependence of the dielectric strength of VHB 4905 *** pre-stretch ratio of 4,the improve-ment of the dielectric strength is about 30%from voltage ramp of 50 V/s to 800 V/***,with an in-house biaxial test platform,the effect of the stretching rate on the dielectric strength is examined for the first *** improvement of the dielectric strength is about 35%from stretching rate of 0.1 mm/s to 5 mm/***,a dielectric strength predictor based on configurational stress is adopted to describe the experimental *** to the predictor,the loading rate affects the dielectric strength of the elastomer mainly by influencing the evolution of the inelastic deformation.

关键词： Dielectric strength dielectric elastomers material viscoelasticity rate-dependence configurational stress

A model reduction approach for discrete-time linear time-variant systems with delayed inputs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

science China(Information sciences) 2024年第4期67卷 197-217页

作者： Ai-Guo WU Guang-Ren DUAN Yu WANG Jie ZHANG School of Mechanical Engineering and Automation Harbin Institute of Technology(Shenzhen) HIT Wuhu Robot Technology Research institute Center for Control science and Technology Southern University of Science and Technology

A model reduction approach is presented for discrete-time linear time-variant input-delayed systems. According to this proposed approach, a dynamical variable is constructed by taking advantage of the current state and historical information of input. It is revealed that the behavior of this dynamical variable is governed by a discrete-time linear delay-free system. It is worth noting that the presented variable transformation does not require the system matrix to be invertible. Based on the reduced delay-free models,stabilizing control laws can be easily obtained for the original delayed system. For the case with a single input delay, the constructed variable is an exact prediction for the future state, and thus the stabilizing control law could be designed by replacing the future state with its prediction. Finally, three discrete-time periodic systems with delayed input are employed to illustrate how to utilize the presented model reduction approaches.

关键词： reduction approach predictor-based feedback time-varying systems delayed input periodic system

Single-wall carbon nanotube fiber non-woven fabrics with a high electrothermal heating response

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 5621-5628页

作者： Xinyu Jiao Lele Xu Xinyang Sun Chao Shi Peng-Xiang Hou Chang Liu Hui-Ming Cheng Shenyang National Laboratory for Materials science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials science and Engineering University of Science and Technology of ChinaHefei 230026China Faculty of Materials science and Engineering/institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Carbon nanotube(CNT)fibers have great promise for constructing multifunctional fabrics with high electrical conductivity,good electro-heating ability,excellent flexibility,and a low ***,the inter-fiber contacts in the fabric greatly reduce these advantages and limit their ***,a simple pressure-fusing method to fabricate single-wall CNT(SWCNT)fiber non-woven fabrics(NWFs)that are composed of interconnected SWCNT fibers with fused joints is reported,which have good flexibility,a low density of 0.46 g/cm^(3),a high electrical conductivity of 3.7×10^(5)S/m,and a record high specific electrical conductivity of 803(S·m^(2))/*** also showed excellent electrical heating ability,so that a temperature of~160℃was rapidly reached at a low voltage of 2 *** with their low density,the SWCNT fiber NWFs are promising for use as a heating unit for low temperature battery protection and de-icing applications.

关键词： carbon nanotube fiber nonwoven fabrics fusing electrothermal heating

Enriched electrophilic oxygen species facilitate acidic oxygen evolution on Ru-Mo binary oxide catalysts

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 1165-1172页

作者： Yaya Wang Yunzhou Wen Yumeng Cheng Xinhong Chen Mengjiao Zhuansun Tongbao Wang Jun Li Debora Meira Huarui Sun Jun Wei Jia Zhou Yuhang Wang Sisi He Shenzhen Key Laboratory of Flexible Printed Electronics Technology Harbin Institute of Technology(Shenzhen)University TownShenzhen 518055China School of science Harbin Institute of Technology(Shenzhen)University TownShenzhen 518055China institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhou 215123China Frontiers science Center for Transformative Molecules Shanghai Jiao Tong UniversityShanghai 200240China science Division Canadian Light SourceSaskatoonSKS7N 2V3Canada photon science Division Argonne National LaboratoryLemontIL60439USA School of Materials science and Engineering Harbin Institute of Technology(Shenzhen)University TownShenzhen 518055China

The polymer electrolyte membrane(PEM)electrolyzers are burdened with costly iridium(Ir)-based catalysts and high operation overpotentials for the oxygen evolution reaction(OER).The development of earth-abundant,highly active,and durable electrocatalysts to replace Ir is a critical step in reducing the cost of green hydrogen *** we develop a Ru5Mo4Ox binary oxide catalyst that exhibits high activity and stability in acidic *** electron-withdrawing property of Mo enriches the electrophilic surface oxygen species,which promotes acidic OER to proceed via the adsorbate evolution *** a result,we achieve a 189 mV overpotential at 10 mA·cm^(-2) and a Tafel slope of 48.8 mV·dec^(-1).Our catalyst demonstrates a substantial 18-fold increase in intrinsic activity,as evaluated by turnover frequency,compared to commercially available RuO_(2) and IrO_(2) ***,we report a stable OER operation at 10 mA·cm^(-2) for 100 h with a low degradation rate of 2.05 mV·h^(-1).

关键词： electrocatalysis oxygen evolution reaction(OER) ruthenium(Ru)-based oxide molybdenum electrophilic oxygen

Brain-inspired chaotic spiking backpropagation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National science Review 2024年第6期11卷 169-179页

作者： Zijian Wang Peng Tao Luonan Chen Key Laboratory of Systems Health science of Zhejiang Province School of Life ScienceHangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences Key Laboratory of Systems Biology Shanghai Institute of Biochemistry and Cell Biology Center for Excellence in Molecular Cell Science Chinese Academy of Sciences Guangdong institute of Intelligence science and Technology Pazhou Laboratory(Huangpu)

Spiking neural networks(SNNs) have superior energy efficiency due to their spiking signal transmission,which mimics biological nervous systems, but they are difficult to train effectively. Although surrogate gradient-based methods offer a workable solution, trained SNNs frequently fall into local minima because they are still primarily based on gradient dynamics. Inspired by the chaotic dynamics in animal brain learning, we propose a chaotic spiking backpropagation(CSBP) method that introduces a loss function to generate brain-like chaotic dynamics and further takes advantage of the ergodic and pseudo-random nature to make SNN learning effective and robust. From a computational viewpoint, we found that CSBP significantly outperforms current state-of-the-art methods on both neuromorphic data sets(***-CIFAR10 and DVS-Gesture) and large-scale static data sets(e.g. CIFAR100 and Image Net) in terms of accuracy and robustness. From a theoretical viewpoint, we show that the learning process of CSBP is initially chaotic, then subject to various bifurcations and eventually converges to gradient dynamics,consistently with the observation of animal brain activity. Our work provides a superior core tool for direct SNN training and offers new insights into understanding the learning process of a biological brain.

关键词： spiking neural networks surrogate gradient local minima backpropagation brain-inspired learning chaos

Investigation on Strengthening Mechanism of China Low-Activation Ferrite Steel upon Thermo-Mechanical Treatment

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 373-387页

作者： Dongtian Yang Liangyin Xiong Hongbin Liao Guoping Yang Xiaoyu Wang Shi Liu institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials science and Engineering University of Science and Technology of ChinaShenyang110016China Center for Fusion science Southwestern Institute of PhysicsChengdu610041China

The objective of this study was to investigate the influence of strengthening mechanisms on the high-temperature mechanical properties of China low-activation ferrite(CLF-1)steel,which underwent thermodynamic design and thermo-mechanical treatment(TMT).The microstructure characterization in the normalized and tempered condition and the TMT condition was carried out using optical microscopy,X-ray diffractometer,and scanning electron microscopy with electron backscatter ***-resolution transmission electron microscopy was employed to determine the crystallographic structures of precipitated *** results indicated that the addition of Ti led to an increase in the allocation of C in MC phase and an enhancement in the content of MC *** to CLF-P steel in the normalized and tempered condition,a 1.5-fold increase in dislocation density and an order of magnitude improvement in MX phase density were achieved after *** formation of high-density nano-scale MC phases during TMT played a significant role in precipitation strengthening due to their favorable coherent relationship with the matrix and low interfacial free *** excellent high-temperature mechanical properties observed in CLF-P steel after TMT can be attributed to the combined effects of precipitation strengthening,dislocation strengthening,and lath strengthening.

关键词： China low-activation ferrite(CLF-1)steel Thermo-mechanical treatment MC phase Crystallographic structure Strengthening mechanism

A combined computational/experimental study of anode-concerned voltage drop in aqueous primary Mg-air batteries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第5期12卷 1854-1866页

作者： Wen Xu Min Deng Darya Snihirova Linqian Wang Yulong Wu Sviatlana V.Lamaka Mikhail L.Zheludkevich Daniel Hoche institute of Surface science Helmholtz-Zentrum Hereon21502 GeesthachtGermany School of Materials science and Engineering Hebei University of Technology300000TianjinChina institute for Materials science Faculty of EngineeringKiel University24143 KielGermany

The voltage drop appearing at Mg anode-electrolyte interface is a critical issue for the battery power and energy density of aqueous primary Mg-air *** respective voltage loss is typically assigned to the deposits layer forming on the anode surface during *** this work,we experimentally and computationally investigate the critical factors affecting the voltage drop at Mg anode towards a deeper understanding of the contribution of deposit and its growth.A two-dimensional(2D)mathematical model is proposed to compute the voltage drop of Mg-0.15Ca wt.%alloy(Mg-0.15Ca)by means of a semi-empirical formulas and experiments-based modification model,considering the effect of discharge current density,the negative difference effect(NDE)and surface deposits layer *** model is utilized to simulate the discharge potential of the anode at predefined experimental current *** computed voltage drop(half-cell voltage)is in good agreement with the experimental *** applicability of the mathematical model is successfully validated on the second material(namely high-purity Mg).

关键词： Aqueous Mg-air battery Voltage drop NDE Charge transfer Deposits-related resistances

维普期刊数据库

A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第4期91卷 155-177页

作者： Jihye Park Jong Hwan Lim Jin-Hyuk Kang Jiheon Lim Ho Won Jang Hosun Shin Sun Hwa Park Interdisciplinary Materials Measurement institute Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Material science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Applied Measurement science University of Science and TechnologyDaejeon 34113Republic of Korea

To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for *** optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis *** electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical *** possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface *** review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage *** with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.

关键词： Scanning electrochemical microscopy Electrocatalyst Electrocatalysis Water splitting Fuel cell Metal-oxygen battery

维普期刊数据库

Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第1期31卷 364-374页

作者： Changlin Li Wei Yang Qiang Gan Yajun Wang Lin Liang Wenbo Zhang Shuangfei Zhu Changgen Feng State Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing 100081China School of Materials science&Engineering Beijing Institute of TechnologyBeijing 100081China

To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force *** is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the *** degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro *** existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more *** has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by *** results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.

关键词： CL-20 co-crystals Molecular dynamics simulation Reactive forcefield Impact response Hot spot Void defect

维普期刊数据库