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Influence of thermal ageing on high-field polarisation characteristics and conductivity behaviour of submarine polymeric cables insulation

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High Voltage 2023年第1期8卷 138-148页

作者： Xize Dai jian Hao Gian Carlo Montanari zheng jian Ruijin Liao Xinlong zheng State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina Department of Energy Aalborg UniversityAalborgDenmark Center for Advanced Power Systems Florida State UniversityTallahasseeFloridaUSA Shinan Power Supply Branch Company of State Grid Chongqing Electric Power Company NananChina Zhoushan Power Supply Branch Company of State Grid Zhejiang Electric Power Company ZhoushanChina

Diagnosing insulation intrinsic ageing is essential for preventing insulation failure of submarine cables,and in case of failure,helping in any decision about maintenance *** this study,a novel aged cable diagnosis approach based on high-voltage frequency domain spectroscopy(HV-FDS)with broader frequency width is proposed to analyse the high-field polarisation characteristics and conductivity behaviour of 500 kV submarine polymeric cables insulation,aiming to support the evaluation of overall insulation *** measurement principle of HV-FDS and relaxation mechanism are stated,and then focus is on studying the extent of change of polarisation and conduction properties of submarine cables insulation as a function of ageing stress and ***,the high-field polarisation characteristics and conductivity behaviour are discussed in-depth based on the carrier transport and trap ***,the novel diagnostic indicator based on the high-field characteristics is extracted to quantify the thermal ageing state of submarine cables *** show that the high-field polarisation characteristics and conductivity behaviour seem to become sensitive diagnostic quantities if measured at reasonably high voltage,which are able to reveal mechanisms associated with thermo-oxidative ageing as that generated in the testing procedure considered in this *** is considerably higher than that experienced in typical dielectric spectroscopy approaches.

关键词： behaviour insulation characteristics

An analytical solution to estimate the settlement of tailings or backfill slurry by considering the sedimentation and consolidation

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International Journal of Mining Science and Technology 2021年第3期31卷 463-471页

作者： Jiahao Qin jian zheng Li Li Research Institute of Mining and Environment(RIME UQAT-Polytechnique) Department of CivilGeological and Mining EngineeringMontréalQuébec H3C 3A7Canada

A common and important task in mining industry is to estimate the settlement or final volume of the tailings or backfill associated with sedimentation and self-weight consolidation. Up to now however, most existing analytical solutions were developed by only considering the settlement induced by consolidation. In this paper, the process of shrinkage tests has been compared with those of sedimentation and consolidation. It was shown that the pore water and particles movement in the sedimentation are very similar to that in the normal shrinkage. The void ratio at the end of sedimentation is thus for the first time considered to be equal to the void ratio at desaturation onset of shrinkage tests. An analytical solution was then proposed to estimate the settlement of tailings or backfill by considering the sedimentation and consolidation. To validate the proposed analytical solution, tailing deposition tests were conducted in two molds to simulate the tailings impoundment and underground mine stope. The required parameters were obtained through shrinkage and consolidation tests. Good agreements were obtained between the measured settlements and those calculated by the proposed solution. The proposed solution can thus be considered as validated and used to evaluate the settlement of tailings or backfill slurry.

关键词： Shrinkage Sedimentation Consolidation Settlement Tailings Backfill

Direct reduction of iron ore by biomass char

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International Journal of Minerals,Metallurgy and Materials 2013年第6期20卷 514-521页

作者： Hai-bin Zuo zheng-wen Hu jian-liang Zhang Jing Li zheng-jian Liu State Key Laboratory of Advenced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

By using thermogravimetric analysis the process and mechanism of iron ore reduced by biomass char were investigated and compared with those reduced by coal and coke. It is found that biomass char has a higher reactivity. The increase of carbon-to-oxygen mole ratio （C/O） can lead to the enhancement of reaction rate and reduction fraction, but cannot change the temperature and trend of each reaction. The reaction temperature of hematite reduced by biomass char is at least 100 K lower than that reduced by coal and coke, the maximum reaction rate is 1.57 times as high as that of coal, and the final reaction fraction is much higher. Model calculation indicates that the use of burden composed of biomass char and iron ore for blast furnaces can probably decrease the temperature of the thermal reserve zone and reduce the CO equilibrium concentration.

关键词： ironmaking biomass char hematite direct reduction process thermogravimetric analysis

NUMERICAL SIMULATIONS OF A CENTERED CONDUCTING BODY ON NATURAL CONVECTION AND HEAT TRANSFER IN AN ENCLOSURE

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Journal of Hydrodynamics 2005年第5期17卷 539-545页

作者： LI Guang-zheng HUANG jian-chun College of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan430074 China

Numerical simulations are performed for laminar natural convection heat transfer from a centered conducting body enclosed in a square cavity. A high accuracy un steady numerical method is used, combining the unique condition of the pressure, the convergent solutions and the streamfunction value of the inside heat conducting body are given simultaneously. Two examples are simulated with this numerical method and compared with the experimental results. The results of the numerical solutions are consistent with the experimental results. It shows that the numerical method is valid and feasible.

关键词： natural convection in an enclosure inside heat conducting body stream value of solid walls unsteady numerical method

High-voltage frequency domain spectroscopy analysis of a thermally aged XLPE submarine cable under continuous and cyclic voltage based on carrier transport and polarisation characteristics

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High Voltage 2022年第3期7卷 473-482页

作者： Xize Dai jian Hao zheng jian Ruijin Liao Xinlong zheng Yiyi Zhang State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina State Grid Zhejiang Electric Power Supply Company ZhoushanChina School of Electrical Engineering Guangxi UniversityNanningChina

In order to ensure the safe operation of submarine cables,it is of great significance to analyse the insulation state of submarine cables from the perspectives of microstructure,carrier transport characteristics and macroscopic dielectric *** this study,based on the high-voltage frequency domain spectroscopy(HV-FDS)measurement system,HV-FDS experiments of fresh and thermally aged submarine cables were carried out under continuous(0.5,2,4 and 10 kV)and cyclic(2-10-2 kV)applied alternating ***,combining the changes of the microstructure structure of cross-linked poly-ethylene(XLPE)insulation,the aggregate structure deterioration model of XLPE was proposed to discuss the physical mechanism of HV-FDS characteristics of submarine cables under different voltages and insulation *** show that the HV-FDS characteristics of submarine cables have significant voltage dependence under contin-uous voltage *** HV-FDS of submarine cables show memory characteristics under cyclic voltage *** with the fresh submarine cable,the thermally aged submarine cable shows more significant voltage dependence and memory charac-teristics of *** memory characteristics of HV-FDS are mainly determined by the carriers transport and the interfacial polarisation caused by the accumulation of polar particles at the electrode/dielectric *** study covers the correlation mecha-nism among the microstructure,carrier transport and macroscopic HV-FDS properties of submarine cable insulation,which lays a foundation for further research and condition evaluation of submarine cables.

关键词： submarine characteristics transport

Cross-linking density and aging constitutive model of HTPB coating under prestrain thermal accelerated aging

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Defence Technology（防务技术） 2020年第2期16卷 439-446页

作者： Yong-qiang Du jian zheng Chao Xiong Shijiazhuang Campus Army Engineering UniversityShijiazhuang 050003China

In order to study the cross-linking density and aging constitutive relationship of HTPB coating during storage,the thermal accelerated aging tests at 0%,3%,6%and 9%prestrains were carried *** crosslinking density of HTPB coating at different aging stages were tested using low-field^1 H NMR and the variation of cross-linking density was *** aging model of cross-linking density considering the chemical aging and the physical stretching factors was *** uniaxial tensile tests were carried out on HTPB coating at different aging stages and the cross-linking density was introduced into Ogden hyperelastic constitutive model as a characterization parameter of correction *** with uniaxial tensile test results,a prestrain aging constitutive model of HTPB coating was *** results show that the cross-linking density of HTPB coating increases rapidly at first and then slowly with the increase of thermal accelerated aging time without *** prestrain conditions,the crosslinking density of HTPB coating decreases at the early stage,and increases rapidly at first and then slowly at the middle and late stages of thermal accelerated *** correlation coefficients of aging model of cross-linking density and aging constitutive model with test results are R>0.9500 and R>0.9900 respectively,which can be used to accurately describe the cross-linking density and aging constitutive relationship of HTPB coating under prestrain accelerated thermal aging conditions.

关键词： Prestrain thermal accelerated aging Low-field^1H NMR Cross-linking density Aging constitutive model

HMFI分子筛Bronsted酸性位点与碱性分子的作用机制

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原子与分子物理学报 2025年第4期42卷 1-7页

作者：郑健秦康秦玉才宋丽娟中石化石油化工科学研究院有限公司北京100083 辽宁石油化工大学辽宁省石油化工催化科学与技术重点实验室抚顺113001

采用密度泛函理论(DFT)方法,以单铝、双铝和三铝酸性位点HMFI分子筛为模型分子筛,计算去质子化能考察HMFI分子筛的本征酸性,以NH_(3)分子作为模型分子,计算NH_(3)分子在HMFI分子筛中的吸附能与去质子化能进行关联性分析,并进一步考察NH_... 详细信息

采用密度泛函理论(DFT)方法,以单铝、双铝和三铝酸性位点HMFI分子筛为模型分子筛,计算去质子化能考察HMFI分子筛的本征酸性,以NH_(3)分子作为模型分子,计算NH_(3)分子在HMFI分子筛中的吸附能与去质子化能进行关联性分析,并进一步考察NH_(3)分子与HMFI分子筛的作用机制.研究表明分子筛Bronsted酸(简称B酸)强度与B酸数量没有强相关性,在考虑B酸位数量的同时须考虑B酸位的分布.酸性位点数量和分布的差异均可以调控NH_(3)分子的吸附构象,并且可以通过调节HMFI分子筛孔道对分子施加相互作用的模式,解析分子的结构和电子性质,精准调控分子的进一步转化.此项工作可以为未来高效多孔材料有效物种活性位的构建提供新思路.

关键词：密度泛函理论 HMFI分子筛 Bronsted酸性质吸附性能

Inconsistent increasing of climate potential productivity resulting from global warming and land use transitions in the Dongting Lake Basin,from 2000 to 2020

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Journal of Mountain Science 2023年第7期20卷 1954-1967页

作者： WANG Ji-ren zheng jian SU jian zheng Bo-hong SUN Zhao-qian School of Architecture and Art Central South UniversityChangsha 410083China School of Architecture Changsha University of Science and TechnologyChangsha 410114China School of Architecture South China University of technologyGuangzhou 510640China

In the face of global warming and increasing impervious surfaces,quantifying the change of climate potential productivity(CPP)is of great significance for the food production *** the Dongting Lake Basin,which is a key area for food production in China,this paper uses meteorological data,as well as Climate Change Initiative Land Cover,and Shuttle Radar Topography Mission digital elevation model to investigate the CPP and its changes from 2000 to *** suitability of land for cultivation(SLC),and the land use/land cover change(LUCC)are also *** results showed that the CPP varied from 9,825 to 20,895 kg ha^(-1).Even though the newly added impervious surfaces indirectly resulted in the decrease of CPP by of 9.81×10~8 kg,overall,the CPP increased at an average rate of 83.7 kg ha^(-1)a^(-1).Global warming is the strongest driver behind CPP increase,and CPP has played an important role in the conversions between cultivated land and other land *** structure of land types tends to be optimized against this challenge.

关键词： Land cultivation Land use/land cover change Climate potential productivity Global warming Dongting Lake Basin

Stochastic Stability of FitzHugh-Nagumo Systems in Infinite Lattice Perturbed by Gaussian White Noise

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Acta Mathematica Sinica,English Series 2011年第11期27卷 2143-2152页

作者： Yan zheng jian Hua HUANG Department of Mathematics National University of Defense Technology Changsha 410073 P. R. China

The current paper is devoted to the study of stochastic stability of FitzHugh-Nagumo systems in infinite lattice perturbed by Gaussian white noise. We first study the dynamics of stochastic FitzHugh-Nagumo systems, then prove the existence and uniqueness of their equilibriums, which mix exponentially. Finally, we investigate asymptotic behavior of equilibriums when the size of noise gets to zero.

关键词： Stochastic stability Gaussian white noise equilibrium FitzHugh-Nagumo systems