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Investigation on effect of semiconducting screen on space charge behaviour of polypropylene-based polymers for HVDC cables

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High Voltage 2022年第5期7卷 968-981页

作者： Mingyu Zhou Haitian Wang Xintong Ren George Chen Yi Luo Fan Yu Global Energy Interconnection research Institute Europe GmbH BerlinGermany The Tony Davies High Voltage laboratory University of SouthamptonSouthamptonHampshireUK Global Energy Interconnection research Institute Co. Ltd.BeijingChina

High voltage direct current(HVDC)power transmission cable is critical for realising sustainability through renewable energy ***-friendly thermoplastic polypropylene(PP)-based polymers/nanocomposites are regarded as promising candidates for replacing current thermoset crosslinked polyethylene(XLPE)*** an essential component of the extruded HVDC cable for improving conductor/insulation interface and suppressing charge injection to insulation at high DC electrical stresses,developing semiconducting(SC)screens that are compatible with PP-based insulation is of similar importance but has not been well studied *** work aims at designing PP-based semiconducting screens and investigating space charge behaviours of SC/PP/SC sandwich specimen to unfold the effect of semiconducting materials,bonding methods,applied DC electric field,and temperature on charge injection,accumulation,transportation,and dissipation in PP-based *** conventional thermal,mechanical,and low field electrical characterisations demonstrated that all of the developed semiconducting materials meet the performance criteria of commercial semiconducting materials,their space charge and local electric field distribution varied significantly at high DC *** with the traditional non-bonded configuration used at lab-scale,charge injection was enhanced in hot-pressed SC/PP/SC samples with tightly bonded interfaces,which better reflects the real situation in extruded *** temperature further intensified charge ***,our results also revealed that high temperature and electric field strongly influence charge mobilities and consequently their distribution and local electric field in PP-based insulations.

关键词： charge insulation effect

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A hippocampus-inspired illumination time-resolved device for neural coding

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Science China Materials 2022年第4期65卷 1087-1093页

作者： Caihong Li Wen Du Hezhuang Liu Mao Yang Hao Xu Jiang Wu Zhiming Wang Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu610054China School of Physics University of Electronic Science and Technology of ChinaChengdu610054China State Key laboratory of Electronic thin films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Artificial photonic synapses have set off a new upsurge for mimicking a series of neural activities in recent *** particular,the investigation of learning and memory behaviors with pressure or emotion and corresponding mechanisms is currently the focus of more ***,a hippocampus-inspired device based on MoS_(2) for illumination time encoding is fabricated,in which the encryption technology is employed for data *** addition,the pressureinduced memory behaviors with full memory function(memory trace)over time such as encoding,storage and retrieval are demonstrated,resulting from the decreasing positive photocurrent of the MoS;*** proposed mechanism of the memory effect when exposed to the light is elucidated in ***,the effect of stress hormone on memory behavior is displayed via different illumination time periods and light *** results indicate the potential application of MoS_(2) devices in artificial neural network.

关键词： illumination time memory trace pressure-induced memory behavior memory encoding memory retrieval

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Controllable preparation and microwave absorption properties of shape anisotropic Fe_(3)O_(4) nanobelts

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Journal of Materiomics 2021年第5期7卷 957-966页

作者： Jialiang Pan Rujing Zhang Jun Ling Min Wang Zechen Li Zhen Zhen Limin He Hongwei Zhu State Key lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China The First Scientific research Institute of Wuxi Wuxi214035JiangsuChina Key laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material AECC Beijing Institute of Aeronautical MaterialsBeijing100095China

To substantially prevent electromagnetic threatens,microwave absorbing materials(MAMs)are required to eliminate surplus electromagnetic *** a typical MAM,Fe_(3)O_(4) particles with complex permittivity and permeability have been widely applied due to the coexistence of magnetic loss and dielectric ***,the necessary high mass fraction significantly limited its applications,thus Fe_(3)O_(4) nanostructures have been extensively investigated to overcome this *** this work,uniform Fe_(3)O_(4) nanobelts were prepared by electrospinning and two-step thermal *** controlling the composition and viscosity of the electrospinning precursor solution,Fe_(3)O_(4) nanobelts with tunable lateral sizes(200 nme1 mm)were *** samples with low content(only 16.7 wt%)Fe_(3)O_(4) exhibited wide maximum effective absorbing bandwidths(EAB)over 3 GHz,and Fe_(3)O_(4) nanobelts with smaller lateral sizes showed a maximum EAB of 4.93 ***,Fe_(3)O_(4) nanobelts with smaller lateral sizes presented superior reflection loss properties,the lowest reflection loss reached-53.93 dB at 10.10 GHz,while the maximum EAB was up to 2.98 *** excellent microwave reflection loss of Fe_(3)O_(4) nanobelts was contributed to the enhanced synergistic effect of magnetic loss,dielectric loss,and impedance matching,originated from the hierarchically cross-linked networks and shape *** study could broaden the practical applications of magnetic absorbers,and provided an approach for the development of shape anisotropic magnetic materials.

关键词： Fe_(3)O_(4) Nanobelts Shape anisotropy Microwave absorption Reflection loss

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Thermoplastic elastomer enhanced interface adhesion and bending durability for flexible organic solar cells

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npj Flexible Electronics 2022年第1期6卷 548-557页

作者： Zihan Xu Yunfei Han Yuanyuan Bai Xingze Chen Jingbo Guo Lianping Zhang Chao Gong Qun Luo Ting Zhang Chang-Qi Ma School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefeiPR China Printable Electronics research Center Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhouPR China i-lab Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhouPR China

Stable interface adhesion and bending durability of flexible organic solar cells(FOSCs)is a basic requirement for its real application in wearable ***,the device performance always degraded during continuous ***,we revealed the weak interface adhesion force between MoO_(3) hole transporting layer(HTL)and the organic photoactive layer was the main reason of poor bending *** insertion of an interface bonding layer with a thermoplastic elastomer,polystyrene-blockpoly(ethylene-ran-butylene)-block-polystyrene(SEBS)effectively improved the interface adhesion force of MoO_(3) HTL and the active layer and decreased the modulus,which ensured higher than 90%of the initial efficiency remaining after 10000 ***,the FOSCs gave an efficiency of 14.18%and 16.15%for the PM6:Y6 and PM6:L8-BO devices,which was among the highest performance of *** results demonstrated the potential of improving the mechanical durability of FOSCs through thermoplastic elastomer interface modification.

关键词： elastomer interface durability

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EasySVM: A visual analysis approach for open-box support vector machines

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Computational Visual Media 2017年第2期3卷 161-175页

作者： Yuxin Ma Wei Chen Xiaohong Ma Jiayi Xu Xinxin Huang Ross Maciejewski Anthony K.H.Tung State Key lab of CAD&CG Zhejiang University Arizona State University National University of Singapore

Support vector machines(SVMs) are supervised learning models traditionally employed for classification and regression analysis. In classification analysis, a set of training data is chosen, and each instance in the training data is assigned a categorical class. An SVM then constructs a model based on a separating plane that maximizes the margin between different classes. Despite being one of the most popular classification models because of its strong performance empirically, understanding the knowledge captured in an SVM remains difficult. SVMs are typically applied in a black-box manner where the details of parameter tuning, training, and even the final constructed model are hidden from the users. This is natural since these details are often complex and difficult to understand without proper visualization tools. However, such an approach often brings about various problems including trial-and-error tuning and suspicious users who are forced to trust these models *** contribution of this paper is a visual analysis approach for building SVMs in an open-box *** goal is to improve an analyst's understanding of the SVM modeling process through a suite of visualization techniques that allow users to have full interactive visual control over the entire SVM training *** visual exploration tools have been developed to enable intuitive parameter tuning, training datamanipulation, and rule extraction as part of the SVM training process. To demonstrate the efficacy of our approach, we conduct a case study using a real-world robot control dataset.

关键词： support vector machines(SVMs) rule extraction visual classification high-dimensional visualization visual analysis

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Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

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Science China Earth Sciences 2015年第9期58卷 1643-1655页

作者： QIN Feng ZHAO Yan LI Quan CAI MaoTang Key laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Nature Resources ResearchChinese Academy of Sciences

The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modem pollen data with contemporary vegetation and climate, and the differences between the pollen assem- blages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region （desert, steppe, mead- ow and forest）. However, differences exist between modern pollen assemblages of the two types of sediments due to the dif- ferent relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of sur- face lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the ten- dency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. Linear regression analysis indicates that the Artemisia/Chenopodiaceae （A/C） ratio in pollen assemblages of surface lake sedi- ments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles.

关键词： modern pollen assemblage surface lake sediment topsoil vegetation climate northwestern China

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Facile Synthesis of S-Fused Multi-Membered Polycyclic Heterocycles:A Construction Strategy towards Thermally Stable Thiepine Derivatives

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Chinese Journal of Chemistry 2023年第1期41卷 13-20页

作者： Binbin Ming Chuan Yan Shoudong Xie Si Liu Yingjian Ren Hao Zong Weinan Chen Gang Zhou lab of Advanced Materials State Key Laboratory of Molecular Engineering of PolymersFudan UniversityShanghai 200438China

S-fused heterocycles have become popular building blocks to construct functional polycyclic *** contrast to the abundant synthetic methodologies for thiophene-fused aromatics,the synthesis of S-heterocycles containing six-membered thiopyran and seven-membered thiepine rings is much less reported owing to their unfavorable synthetic protocols and the thermal ***,a series of thiepine-containing polycyclic S-heterocycles have been successfully synthesized via different synthetic routes which involve initial construction of sulfur bridges and final ring-closure ***,the dilithium intermediates are ex-cluded,which facilitates the fusion on the thiepine ring with different S-heterocycles,including thiophene and thiopyran ***,a S-fused multi-membered polycyclic compound simultaneously involving thiophen,thiopyran,and thiepine rings has been successfully ***,nucleus-independent chemical shift calculations reveal that the incorporated thiopyran and thiepine rings demonstrate aromatic and nonaromatic characteristics,***,the thermal stabilities of the thiepine derivatives have been tremendously improved after the fusion on the three vinyl groups in the thiepine unit,which is attributed to the enhancements of the activation energies for the S-extrusion reactions,as revealed by density functional theory ***,our findings not only provide a facile synthetic methodology for S-fused multi-membered polycyclic heterocycles,but also furnish a novel construction strategy towards thermally stable thiepine derivatives.

关键词： Sulfur heterocycles Fused-ring systems Thiepine Thiopyran Aromaticity

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BROADCAST SCHEDULING WITH MIMO LINKS IN MULTI-HOP AD HOC NETWORKS

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Journal of Electronics(China) 2007年第4期24卷 477-483页

作者： Zhang Guanghui Li Jiandong Zhao Min Li Changle State Key lab. of ISN Information Science Inst. Broadband Wireless Communications Lab. Xidian University Xi＇an 710071 China

As the current medium access control protocols with Multiple Input Multiple Output （MIMO） links only bear point to point service, broadcast scheduling algorithm in ad hoc networks with MIMO links is proposed. The key to the proposed broadcast scheduling algorithm is the time slot scheduling algorithm which guarantees collisi~）n-free transmissions for every node and the mini- mum frame length. The proposed algorithm increases the simultaneous transmissions of MIMO links efficiently. Due to the interference null capacity of MIMO links, the interference node set of each node can decrease from two-hop neighbors to one-hop neighbors possibly. Simulation results show that our algorithm can greatly improve network capacity and decrease average packet delay.

关键词： Multiple Input Multiple Output (MIMO) Time Division Multiple Access (TDMA) Broadcast Multihop ad hoc network

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Repeated Strike Process During Disconnector Operation in Ultra-High Voltage Gas-Insulated Switchgear

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Plasma Science and Technology 2016年第3期18卷 247-253页

作者：关永刚蔡元纪陈维江刘卫东李志兵岳功昌张俊民 State Key lab of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China State Grid Corporation of China Beijing 100031China China Electric Power research Institute Beijing 100192China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Very fast transient over-voltage （VFTO）, induced by disconnector operations in gas- insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the ex- perimentai results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO.

关键词： disconnector (DS) repeated strike process discharge statistical breakdowncharacteristics ultra-high voltage (UHV) very fast transient over-voltage (VFTO)

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Intratympanic injection of hydrogel nanodrug for the prevention and treatment of sensorineural hearing loss

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中华耳科学杂志:英文版 2023年第4期18卷 235-239页

作者： Tianying Zhai Pingping Ai Zhaohui Tang Chaoliang He Xuesi Chen Shiming Yang Nan Wu Senior Department of Otolaryngology-Head&Neck Surgery PLA General HospitalBeijingChina National Clinical research Center for Otolaryngologic Disease BeijingChina State Key lab of Hearing Science Ministry of EducationBeijingChina Beijing Key lab of Hearing Impairment Prevention&Treatment BeijingChina Zhejiang Chinese Medical University HangzhouChina Changchun Institute of Applied Chemistry Chinese Academy of SciencesChangchunChina

Safe and efficient drug delivery to the inner ear has always been the focus of prevention and treatment of sensorineural *** rapid development of nanodrug delivery systems based on hydrogel has provided a new *** them,thermo-sensitive hydrogels promote the development of new dosage form for intratympanic *** smart biomaterial could transform to semisolid phase when the temperature ***-sensitive hydrogel nanodrug delivery system is expected to achieve safe,efficient,and sustained inner ear drug *** article introduces the key techniques and the latest progress in this field.

关键词： Thermo-sensitive hydrogel Nanodrug Sensorineural hearing loss Intratympanic injection

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