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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

A novel DEM reconstruction strategy based on multi-frequency In SAR in highly sloped terrain

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Science China(Information Sciences) 2017年第8期60卷 243-245页

作者： Tao ZENG tiandong LIU Zegang DING Qi ZHANG Zhen WANG Teng LONG Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of Technology

Interferometric Synthetic Aperture Radar(InSAR)has been proposed as a technique for the reconstruction of the Digital Elevation Model(DEM),which is widely used in global terrain mapping mission[1].The DEM reconstruction methods of In SAR technique are usually based on the so-called phase unwrapping(PU)*** highly sloped terrain,the interferometric phase gradients(IPG)of the adjacent pixels are more thanπ.Therefore,the traditional PU methods

关键词： SAR In of DEM IPG on Figure LAPS A novel DEM reconstruction strategy based on multi-frequency In SAR in highly sloped terrain

Hydrodynamic Modeling and Parameter Identification of a Bionic Underwater Vehicle:RobDact

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Cyborg and Bionic Systems 2022年第1期2022卷 164-176页

作者： Qiyuan Cao Rui Wang tiandong Zhang Yu Wang Shuo Wang State Key Laboratory of Management and Control for Complex Systems Institute of A utomationChinese Academy of SciencesBeijingChina School of Artific ial Itelligence University of Chinese Academy of Sciences BeijingChina Center for Excellence in Brain Science and Itelligence Technology Chinese Academy of SciencesShanghaiChina

In this paper,the hydrodynamic modeling and parameter identifcation of the RobDact,a bionic underwater vehide inspired byDactylopteridae,are carried out based on computational fluid dynamics(CFD)and force measurement ***,thePaper briely describes the RobDact,then establishes the kinematis model and rigid body dynamics model of the RobDactaccording to the hydrodynamic force and moment *** CFD simulations,the hydrodynamic force of theRobDact at diferent speeds is obtained,and then,the hydrodynamic model parameters are ***,themeasurement platform is developed to obtain the relationship between the thrust generated by the RobDact and the inputfluctuation parameters,Finally,combining the rigid body dynamics model and the fin'thrust mapping model,thehydrodynamic model of the RobDact at diferent motion states is constructed.

关键词： dynamics(CFD) equations hydrodynamic

Functional data analysis: An application to COVID-19 data in the United States in 2020

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Quantitative Biology 2022年第2期10卷 172-187页

作者： Chen Tang tiandong Wang Panpan Zhang Research School of Finance Actuarial Studies&StatisticsThe Australian National UniversityCanberraACT 2601Australia Department of Statistics Texas A&M UniversityCollege StationTX 77843USA Department of Biostatistics Epidemiology and InformaticsUniversity of PennsylvaniaPhiladelphiaPA 19104USA

Background: In this paper, we conduct an analysis of the COVID-19 data in the United States in 2020 via functional data analysis methods. Through this research, we investigate the effectiveness of the practice of public health measures, and assess the correlation between infections and deaths caused by the COVID-19. Additionally, we look into the relationship between COVID-19 spread and geographical locations, and propose a forecasting method to predict the total number of confirmed cases ***: The functional data analysis methods include functional principal analysis methods, functional canonical correlation analysis methods, an expectation-maximization (EM) based clustering algorithm and a functional time series model used for ***: It is evident that the practice of public health measures helps to reduce the growth rate of the epidemic outbreak over the nation. We have observed a high canonical correlation between confirmed and death cases. States that are geographically close to the hot spots are likely to be clustered together, and population density appears to be a critical factor affecting the cluster structure. The proposed functional time series model gives more reliable and accurate predictions of the total number of confirmed cases than standard time series ***: The results obtained by applying the functional data analysis methods provide new insights into the COVID-19 data in the United States. With our results and recommendations, the health professionals can make better decisions to reduce the spread of the epidemic, and mitigate its negative effects to the national public health.

关键词： COVID-19 canonical correlation cluster analysis functional time series forecasting principal component analysis

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Discussion of‘On studying extreme values and systematic risks with nonlinear time series models and tail dependence measures’

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Statistical Theory and Related Fields 2021年第1期5卷 38-40页

作者： tiandong Wang Jun Yan Department of Statistics Texas A&M UniversityCollege StationTXUSA Department of Statistics University of ConnecticutStorrsCTUSA

We congratulate *** for this timely review on recent advances in extreme value theory for heterogeneous populations and on time series models for extreme *** is a substantial *** only does it give a summary of the state-of-the-art work in time series modelling of extremes but also suggests interesting methodological and applied research *** discussion focuses on extremal dependence metrics and practical applications for the time series models.

关键词： extreme nonlinear series

Short-term photovoltaic power forecasting based on a new hybrid deep learning model incorporating transfer learning strategy

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Global Energy Interconnection 2024年第6期7卷 825-835页

作者： tiandong Ma Feng Li Renlong Gao Siyu Hu Wenwen Ma State Grid Ningxia Electric Power Co. LtdYinchuan 750001P.R.China China Electric Power Research Institute Nanjing 200003P.R.China

The accurate prediction of photovoltaic(PV)power generation is an important basis for hybrid grid *** the expansion of the scale of PV power plants and the popularization of distributed PV,this study proposes a multilayer PV power generation prediction model based on transfer learning to solve the problems of the lack of data on new PV bases and the low accuracy of PV power generation *** proposed model,called DRAM,concatenates a dilated convolutional neural network(DCNN)module with a bidirectional long short-term memory(BiLSTM)module,and integrates an attention ***,the processed data are input into the DCNN layer,and the dilation convolution mechanism captures the spatial features of the wide sensory field of the input ***,the temporal characteristics between the features are extracted in the BiLSTM ***,an attention mechanism is used to strengthen the key features by assigning weights to efficiently construct the relationship between the features and output *** addition,the power prediction accuracy of the new PV sites was improved by transferring the pre-trained model parameters to the new PV site prediction *** this study,the pre-training of models using data from different source domains and the correlations between these pre-trained models and the target domain were analyzed.

关键词： Multi-layer PV power generation prediction model Pre-training model Parameter transfer

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

Physical and Chemical Properties of Sediments in Huainan Segment of Huaihe River

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Journal of China University of Mining and Technology 2005年第1期15卷 41-47页

作者： CHENGYong-hong XUJun WANGJuan tiandong CHENJun GAOZhi-kang DepartmentofChemistryandBiology HuainanNormalUniversityHuainanAnhui232001China InstituteofHuainanEnvironmentalScience HuannanAnhui232001China

The chemical and physical properties of nitrogen and phosphorus as well as their concentrations in the over- lying water, pore-water and sediments in Huainan segment of the Huaihe river were analyzed. The chemical forms of phosphorus in sediments were differentiated by a sequential fraction method. The results revealed that the NH+4 -N content in pore-water of 6 surface sediments is obviously higher than that in overlying water, indicating that there is a dynamic tendency of releasing NH+4 -N from sediment into overlying water. Chemical compound of nitrogen differs among segments of the river, while phosphorus has no such difference. Calcium bound phosphate (Ca-P) and iron bound phosphate (Fe-P) accounts for 60 % of the total phosphorus, and occluded-P (O-P) accounts for less than 20 %. Our findings indicate that 1) industrial waste water and domestic sewage have contributed to the excessive nu- trient salts in Huaihe river, 2) decreased water flow during low water periods, and the interaction between sediments and overlying water disturbed by transport ships accelerate nutrient salt releasing into overlying water, which results in eutrophication of the river.

关键词： sediments nitrogen phosphorus fraction Huaihe river

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Carbon nanotubes and hexagonal boron nitride nanosheets co-filled ethylene propylene diene monomer composites:Improved electrical property for cable accessory applications

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High Voltage 2024年第3期9卷 546-555页

作者： tiandong Zhang Huiduo Xu Chuanxian Dai Changhai Zhang Yongquan Zhang Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbinChina

Rubber-based composites based on ethylene propylene diene monomer(EPDM)with excellent non-linear electrical conductivity are preferred to serve as reinforced insu-lation in cable accessories,which can self-adaptively regulate electric field distribution and avoid electric field concentration due to the non-linear *** 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 *** results show that with the increase of CNT loading content,the non-linear conductivity of CNT/h-BN/EPDM com-posites becomes more prominent,accompanying the decrease of threshold field strength and increase of non-linear ***,the electric breakdown strength of CNT/h-BN/EPDM composites seriously deteriorates due to the increase of CNT content and *** incorporating 10 wt.%h-BN into the com-posites,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℃,*** 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： composites hexagonal boron

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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