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HIGH VOLTAGE 2024年第3期9卷 546-555页

作者： zhang, Tiandong Xu, Huiduo Dai, Chuanxian zhang, changhai zhang, Yongquan Chi, Qingguo Harbin Univ Sci & Technol Sch Elect & Elect Engn Harbin 150080 Peoples R China

Rubber-based composites based on ethylene propylene diene monomer (EPDM) with excellent non-linear electrical conductivity are preferred to serve as reinforced insulation in cable accessories, which can self-adaptively regulate electric field distribution and avoid electric field concentration due to the non-linear conductivity. The conductive carbon nanotubes (CNT) are filled into EPDM to improve the non-linear conductivity, while the insulating hexagonal boron nitride nanosheets (h-BN) are used to reconcile the electric breakdown strength. The results show that with the increase of CNT loading content, the non-linear conductivity of CNT/h-BN/EPDM composites becomes more prominent, accompanying the decrease of threshold field strength and increase of non-linear coefficient. However, the electric breakdown strength of CNT/h-BN/EPDM composites seriously deteriorates due to the increase of CNT content and temperature. By incorporating 10 wt.% h-BN into the composites, the reduction percentage of breakdown strength can be significantly lowered, which is 19.95% of neat EPDM and 13.74% of CNT/h-BN/EPDM composites at 70 & DEG;C, respectively. The COMSOL Multiphysics simulation results demonstrate that using the CNT/h-BN/EPDM composite as the reinforced insulation can eliminate the electric field concentration of the cable accessory as well as enable the cable accessory with good lightning shock resistance.

关键词： NONLINEAR CONDUCTIVITY

Enhanced High-Temperature Energy Storage Performance of All-Organic Composite Dielectric via Constructing Fiber-Re in forced Structure

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Energy & Environmental Materials 2024年第2期7卷 299-307页

作者： Mengjia Feng Yu Feng changhai zhang Tiandong zhang Xu Tong Qiang Gao Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China

Optimizing the high-temperature energy storage characteristics of energy storage dielectrics is of great significance for the development of pulsed power devices and power control *** a polymer with a higher glass transition temperature(T_(g))as the matrix is one of the effective ways to increase the upper limit of the polymer operating ***,current high-T_(g)polymers have limitations,and it is difficult to meet the demand for high-temperature energy storage dielectrics with only one *** example,polyetherimide has high-energy storage efficiency,but low breakdown strength at high *** has high corona resistance,but low high-temperature energy storage *** this work,combining the advantages of two polymer,a novel high-T_(g)polymer fiber-reinforced microstructure is *** is designed as extremely fine fibers distributed in the composite dielectric,which will facilitate the reduction of high-temperature conductivity loss for *** the same time,due to the high-temperature resistance and corona resistance of polyimide,the high-temperature breakdown strength of the composite dielectric is *** the polyimide content with the best high-temperature energy storage characteristics is determined,molecular semiconductors(ITIC)are blended into the polyimide fibers to further improve the high-temperature ***,excellent high-temperature energy storage properties are *** 0.25 vol%ITIC-polyimide/polyetherimide composite exhibits high-energy density and high discharge efficiency at 150℃(2.9 J cm^(-3),90%)and 180℃(2.16 J cm^(-3),90%).This work provides a scalable design idea for high-performance all-organic high-temperature energy storage dielectrics.

关键词： all-organic energy storage density high-temperature high-temperature breakdown strength

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Significantly Improved High-Temperature Energy Storage Performance of BOPP Films by Coating Nanoscale Inorganic Layer

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Energy & Environmental Materials 2024年第2期7卷 30-38页

作者： Tiandong zhang Hainan Yu Young Hoon Jung changhai zhang Yu Feng Qingguo Chen Keon Jae Lee Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 350701Korea

Biaxially oriented polypropylene(BOPP)is one of the most commonly used commercial capacitor films,but its upper operating temperature is below 105℃due to the sharply increased electrical conduction loss at high *** this study,growing an inorganic nanoscale coating layer onto the BOPP film's surface is proposed to suppress electrical conduction loss at high temperature,as well as increase its upper operating *** kinds of inorganic coating layers that have different energy band structure and dielectric property are grown onto the both surface of BOPP films,*** effect of inorganic coating layer on the high-temperature energy storage performance has been systematically *** favorable coating layer materials and appropriate thickness enable the BOPP films to have a significant improvement in high-temperature energy storage ***,when the aluminum nitride(AIN)acts as a coating layer,the AIN-BOPP-AIN sandwich-structured films possess a discharged energy density of 1.5 J cm^(-3)with an efficiency of 90%at 125℃,accompanying an outstandingly cyclic *** the discharged energy density and operation temperature are significantly enhanced,indicating that this efficient and facile method provides an important reference to improve the high-temperature energy storage performance of polymer-based dielectric films.

关键词： coating layer energy storage interfacial barrier polymer films

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货币政策对企业劳动投资效率的影响研究

财经理论与实践 2024年第1期45卷 34-40页

作者：张长海耿歆雨王帅旗海南大学国际商学院海南海口570228 天健会计师事务所浙江杭州310000

基于2010—2020年我国A股上市公司的相关数据,对货币政策与企业劳动投资效率之间的关系进行探讨。研究发现,在货币政策紧缩时,企业劳动投资效率会有明显的提高,会计稳健性的提高以及自由现金流量的减少是紧缩性货币政策影响企业劳动投... 详细信息

基于2010—2020年我国A股上市公司的相关数据,对货币政策与企业劳动投资效率之间的关系进行探讨。研究发现,在货币政策紧缩时,企业劳动投资效率会有明显的提高,会计稳健性的提高以及自由现金流量的减少是紧缩性货币政策影响企业劳动投资效率的主要作用机制。进一步研究发现,高质量的公司治理水平会抑制紧缩性货币政策对企业劳动投资效率的影响。非效率劳动投资分组检验结果表明,紧缩性货币政策对企业劳动投资效率的促进效应,更多地表现为抑制劳动投资过度。

关键词：货币政策劳动投资效率会计稳健性自由现金流量

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Non-linear electrical conductivity of ethylene-propylene-diene monomer-based composite dielectrics by tuning inorganic fillers

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High Voltage 2023年第4期8卷 781-790页

作者： Tiandong zhang Hao Li changhai zhang Chao Tang Zhonghua Li Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbinChina

In this study,three kinds of inorganic fillers are chosen and filled into ethylene-propylenediene monomer(EPDM)matrix,including silicon carbide,copper calcium titanate(CCTO),and vanadium dioxide(VO2).The electrical properties of the three modified composites at different temperatures have been systematically *** intrinsic conductance behaviours of different inorganic fillers on the direct current conductance and electric breakdown strength of the composite dielectrics are also analysed,and the possible mechanism for non-linear conductivity is *** electrical conductivity increases with the increase of fillers content,where 30 wt.%CCTO/EPDM composite dielectric has a high non-linear coefficient of *** increase in temperature can further increase the conductivity of the composites,accompanying a lower breakdown *** the temperature rises to 70℃,the VO2/EPDM composite has a higher conductivity,but the electric breakdown strength degrades *** simulation results show that the composites with non-linear electrical conductivity characteristics can effectively uniform the electric field and solve the problem of electric field concentration at the root of the stress cone,which is beneficial to improving the safe operation of the cable accessories.

关键词： composite composites conductivity

Tunable polarization-drived high energy storage performances in flexible PbZrO_(3)films by growing Al_(2)O_(3)nanolayers

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Journal of Advanced Ceramics 2023年第11期12卷 2123-2133页

作者： Chao Yin Tiandong zhang Zhuangzhuang Shi Bowen zhang changhai zhang Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China

In recent years,PbZrO_(3)(PZO)films have become favorable electric storage materials due to the unique electric field-induced phase transition behavior,but the severe hysteresis effect leads to low energy storage density and *** this work,inserting Al_(2)O_(3)(AO)insulation nanolayers is proposed to tune the polarization behavior of flexible PZO films,anticipating optimization of energy storage *** results show that the thickness of the AO nanolayers has a deep influence on the polarization behavior of the PZO films,and PZO/AO/PZO(PAP)sandwiched films with 8 nm AO interlayer deliver relaxor ferroelectric-like polarization instead of antiferroelectric *** further utilize the AO nanolayers as top/bottom layers,the linear-like polarization and the highest breakdown strength are achieved in the AO/PZO/AO/PZO/AO(APAPA8)multilayer films,leading to both high discharged energy storage density of 35.2 J/cm^(3) and efficiency of 92.9%,as well as excellent fatigue and bending endurance,good temperatures,and frequency *** tunable polarization induced by growing the AO nanolayers makes antiferroelectric PZO films have great potential to be used as energy storage dielectrics.

关键词： sol-gel flexible antiferroelectric polarization energy storage

Tunable polarization-drived superior energy storage performance in PbZrO_(3) thin films

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Journal of Advanced Ceramics 2023年第5期12卷 930-942页

作者： Tiandong zhang Zhuangzhuang Shi Chao Yin changhai zhang Yue zhang Yongquan zhang Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 305-701Republic of Korea

Antiferroelectric PbZrO_(3)(AFE PZO)films have great potential to be used as the energy storage dielectrics due to the unique electric field(E)-induced phase transition ***,the phase transition process always accompanies a polarization(P)hysteresis effect that induces the large energy loss(Wloss)and lowers the breakdown strength(EBDS),leading to the inferior energy storage density(Wrec)as well as low *** this work,the synergistic strategies by doping smaller ions of Li^(+)–Al^(3+)to substitute Pb2+and lowering the annealing temperature(T)from 700 to 550℃are proposed to change the microstructures and tune the polarization characters of PZO films,except to dramatically improve the energy storage *** prepared Pb_((1−x))(Li_(0.5)Al_(0.5))_(x)ZrO_(3)(P_((1−x))(L_(0.5)A_(0.5))_(x)ZO)films exhibit ferroelectric(FE)-like rather than AFE character once the doping content of Li^(+)–Al^(3+)ions reaches 6 mol%,accompanying a significant improvement of W_(rec) of 49.09 J/cm^(3),but the energy storage efficiency(η)is only 47.94%due to the long-correlation of FE ***,the low-temperature annealing is carried out to reduce the crystalline degree and the P loss.P_(0.94)(L_(0.5)A_(0.5))_(0.06)ZO films annealed at 550℃deliver a linear-like polarization behavior rather than FE-like behavior annealed at 700℃,and the lowered remanent polarization(P_(r))as well as improved E_(BDS)(4814 kV/cm)results in the superior Wrec of 58.7 J/cm^(3) and efficiency of 79.16%,simultaneously possessing excellent frequency and temperature stability and good electric fatigue tolerance.

关键词： lead zirconate ionic pair polarization breakdown strength energy storage

High-temperature energy storage dielectric with inhibition of carrier injection/migration based on band structure regulation

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InfoMat 2023年第2期5卷 22-33页

作者： Guang Liu Qingquan Lei Yu Feng changhai zhang Tiandong zhang Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbinPeople's Republic of China

Dielectric capacitors have a high power density,and are widely used in military and civilian *** main problem lies in the serious deterioration of dielectric insulation performance at high *** this study,a polycarbonate(PC)-based energy storage dielectric was designed with BN/SiO_(2)heterojunctions on its *** on this structural design,a synergistic suppression of the carrier injection and transport was achieved,significantly improving the insulating properties of the polymer *** particular,the composite film achieves optimal high-temperature energy-storage *** composite film can withstand an electric field intensity of 760 MV m^(-1)at 100℃and obtain an energy storage density of 8.32 J cm^(-3),while achieving a breakthrough energy storage performance even at 150℃(610 MV m^(-1),5.22 J cm^(-3)).Through adjustment of the heterojunction structure,free adjustment of the insulation performance of the material can be realized;this is of great significance for the optimization of the material properties.

关键词： electron injection and transport heterojunction high temperature energy storage characteristics insulation polycarbonate

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高温天气对籼稻结实率的影响

安徽农学通报 2024年第8期30卷 1-5页

作者：曹哲群蔡冬梅汪益鸣张长海汪向东桐城市水稻研究所/桐城市种子管理站安徽桐城231400 桐城市气象局安徽桐城231400 桐城市种植业管理中心安徽桐城231400

探讨自然高温天气对水稻的影响,可以为耐高温品种选择、高温热害评估和减轻高温热害措施提供相应参考。本试验统计分析2022年8月1—23日的气温,以此时段抽穗的108份籼型水稻材料为研究对象,总结分析了水稻样本材料在孕穗期、抽穗开花期... 详细信息

探讨自然高温天气对水稻的影响,可以为耐高温品种选择、高温热害评估和减轻高温热害措施提供相应参考。本试验统计分析2022年8月1—23日的气温,以此时段抽穗的108份籼型水稻材料为研究对象,总结分析了水稻样本材料在孕穗期、抽穗开花期和灌浆初期的平均气温和受高温热害天数,计算其结实率。结果表明,8月1—23日平均温度31.53℃,杂交籼稻材料和常规籼稻材料平均结实率分别为80.48%和76.73%,杂交籼稻的抗高温能力总体优于常规籼稻,高温热害程度与高温强度、高温时间密切相关,整体呈现温度越高,结实率越低的趋势,开花盛期高温对籼稻结实率影响最大。提出了防御高温热害损失的技术要点,包括选择耐高温品种、合理安排播期、提高栽培技术以及采取有效措施减轻高温热害损失等。

关键词：高温天气籼稻结实率高温时段抽穗开花期

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Resilience assessment and optimization method of city road network in the post-earthquake emergency period

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 765-779页

作者： Wang Haoran Xiao Jia Li Shuang Zhai changhai Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information TechnologyHarbin Institute of TechnologyHarbin 150090China

The post-earthquake emergency period,which is a sensitive time segment just after an event,mainly focuses on saving life and restoring social *** improve the seismic resilience of city road networks,a resilience evaluation method used in the post-earthquake emergency period is *** road seismic damage index of a city road network can consider the influence of roads,bridges and buildings along the roads,*** road capacity after an earthquake.A function index for a city road network is developed,which reflects the connectivity,redundancy,traffic demand and traffic function of the *** optimization model for improving the road repair order in the post-earthquake emergency period is also developed according to the resilience evaluation,to enable decision support for city emergency management and achieve the best seismic resilience of the city road *** optimization model is applied to a city road network and the results illustrate the feasibility of the resilience evaluation and optimization method for a city road network in the post-earthquake emergency period.

关键词： city road network post-earthquake emergency period traffic demand resilience evaluation optimization model

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