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Significantly enhanced varistor properties of CaCu_(3)Ti_(4)O_(12) based ceramics by designing superior grain boundary:Deepening and broadening interface states

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Journal of Materials Science & Technology 2022年第13期108卷 82-89页

作者： Zhuang Tang kai ning Zhiyao Fu Ze Lian Kangning Wu Shoudao Huang State Key Laboratory of Disaster Prevention and Reduction for Power Grid Transmission and Distribution Equipment SGCC(State Grid Corporation of China)Changsha 410000China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China State Grid Shanxi Electric Power Research Institute Taiyuan 030001China State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi’an 710049China

Significantly enhanced varistor properties via tailoring interface states were obtained in Ca_(1-2x/3)Y_(x)Cu_(3)Ti_(4)O_(12)-SrCu_(3)Ti_(4)O_(12) composite *** breakdown field was improved to 35.8 kV cm^(-1) and the nonlinear coefficient in 0.1-1 mA cm^(-2) was enhanced to 14.6 for Ca_(0.67)Y_(0.5)Cu_(3)Ti_(4)O_(12)-SrCu_(3)Ti_(4)O_(12).Noticeably,the withstand voltage of single grain boundary reached up to 24 V while the reported ones were constant to about 3 *** improved properties were attributed to the formation of superior grain boundary rather than the reduced grain ***,with distinct discrepancy of nonlinear performance in the composites,the resistance and activation energy of grain boundary exhibited little *** on the double Schottky barrier at grain boundary and the field-assisted thermal emission model,it was found that the excellent electrical nonlinearity arose from the formation of deeper and broader interface states at grain *** this case,interface states were not easily entirely filled and the barrier could maintain its height under applied *** work provides a novel routine for enhancing the varistor properties of CaCu_(3)Ti_(4)O_(12) based ceramics by manipulating interface states at grain boundary.

关键词： Schottky barrier Grain boundary Varistor ceramics Interface states

Indirect approach for predicting cutting force coefficients and power consumption in milling process

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Advances in Manufacturing 2022年第1期10卷 101-113页

作者： kai-ning Shi ning Liu Cong-Le Liu Jun-Xue Ren Shan-Shan Yang Wei Chit Tan Key Laboratory of High Performance Manufacturing for Aero Engine Department of Mechanical EngineeringMinistry of Industry and Information TechnologyNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China Engineering Research Centre of Advanced Manufacturing Technology for Aero Engine Department of Mechanical EngineeringMinistry of EducationNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China Virtual Manufacturing Group Smart Manufacturing DivisionAdvanced Remanufacturing and Technology Centre3 Cleantech Loop#01-01CleanTech TwoSingapore 637143Singapore

Accurate energy consumption modeling is an essential prerequisite for sustainable ***,cutting-power-based models have garnered significant attention,as they can provide more comprehensive information regarding the machining energy consumption ***,their implementation is challenging because new cutting force coefficients are typically required to address new workpiece ***,cutting force coefficients are calculated at a high operation cost as a dynamometer must be ***,a novel indirect approach for estimating the cutting force coefficients of a new tool-workpiece pair is proposed *** key idea is to convert the cutting force coefficient calculation problem into an optimization problem,whose solution can be effectively obtained using the proposed simulated annealing ***,the cutting force coefficients for a new tool-workpiece pair can be estimated from a pre-calibrated energy consumption *** experiments performed using different machine tools clearly demonstrate the effectiveness of the developed *** studies with measured cutting force coefficients reveal the decent accuracy of the approach in terms of both energy consumption prediction and instantaneous cutting force *** proposed approach can provide an accurate and reliable estimation of cutting force coefficients for new workpiece materials while avoiding operational or economic problems encountered in traditional force monitoring methods involving ***,this study may significantly advance the development of sustainable manufacturing.

关键词： Sustainable manufacturing Cutting force coefficients Energy consumption Machining processSimulated annealing

Holocene high lake-levels and pan-lake period on Badain Jaran Desert

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Science China Earth Sciences 2016年第8期59卷 1633-1641页

作者： WANG NaiAng ning kai LI ZhuoLun WANG YiXin JIA Peng MA Ling College of Earth and Environmental Sciences Lanzhou University Lanzhou 730000 China History & Culture School of Lanzhou University Lanzhou 730000 China

Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred(11–10 cal kyr BP). Many lakes reached their maximal water-level during 8.6–6.3 cal kyr BP and retreated or dried up in the late Holocene(about 3.5–0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr^(-1) for 7.7–5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture.

关键词： Badain Jaran Desert Holocene High lake-level Pan-lake period Peat period Water balance Prehistoric culture

A DFT Study of 2-Bromothiophene Adsorption on the Rh(111)Surface

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Chinese Journal of Structural Chemistry 2010年第7期29卷 1051-1060页

作者： CHEN Zhan-Hong DING kai-ning XU Xiang-Lan LI Jun-Jian Department of Information Technology Fujian Education College Fuzhou Fujian 350001 China Department of Chemistry Fuzhou University Fuzhou Fujian 350108 China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China

Adsorption behaviors of 2-bromothiophene on the Rh（111） surface were discussed with DFT. The results revealed that adsorption at the parallel hol site and bridge site was the most stable. After adsorption, bond length of 2-bromothiophene changed significantly. Molecular plane was distorted, and C-H （Br, S） in the molecule was oblique and upswept against the metal surface. Vertical adsorption site was less stable than the plane adsorption site, but there was no distortion for the thiophene ring after adsorption. Aromaticity of 2-bromothiophene was destroyed at the hol and bridge adsorption sites, and the carbon atom in the thiophene ring presented quasi-sp3 hybfidizaton. After adsorption at the parallel hol, 2-bromothiophene obtained 0.86 electrons in total, and Rh（111） surface lost 2.08 electrons in all.

关键词： 2-bromothiophene Rh(111) DFT adsorption slab model

Boundary Stabilization of Stochastic Delay Reaction-Diffusion Systems 36

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Boundary Stabilization of Stochastic Delay Reaction-Diffusio...

Surface energy and water vapor fluxes observed on a megadune in the Badain Jaran Desert, China

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作者： Xiao-Zhen Liu Xiao-Hua Ding kai-ning Wu Department of Mathematics Harbin Institute of Technology at Weihai

ISBN: (纸本)9781538629185

This paper considers the boundary stabilization of stochastic delay reaction-diffusion systems（SDRDSs）.We present the integral-form Lyapunov stability lemma for SDRDSs which provides the foundation of stability analysis for stochastic reaction-diffusion systems. Then, we design a boundary controller and obtain a criterion to guarantee the globally stochastically asymptotical stability of SDRDSs with Neumann boundary conditions. In addition, when the external disturbances enter in a given systems, we design a boundary controller and get the sufficient condition for the mean-square H∞ performance. Two numerical examples verifying the validity of the results are obtained in this paper.

关键词： Stochastic Reaction-Diffusion Systems Delay Boundary Control Stabilization H Infinity Performance

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Journal of Arid Land 2015年第5期7卷 579-589页

作者： HU Wenfeng WANG Nai'ang ZHAO Liqiang ning kai ZHANG Xunhe SUN Jie Center for Climate Change and Hydrologic Cycle in Arid Region College of Earth and Environmental Science Lanzhou University College of Geographical Science and Tourism Xinjiang Normal University

The Badain Jaran Desert is the second-largest area of shifting sands in China. Our first measurements of the energy components and water vapor fluxes on a megadune using eddy covariance technology were taken from April 2012 to April 2013. The results indicate that the Iongwave and shortwave radiative fluxes exhibited large fluctuations and seasonal dynamics. The total radiative energy loss by Iongwave and shortwave radiation was greater on the megadune than from other underlying surfaces. The radiation partitioning was different in different seasons. The land-atmosphere interaction was primarily represented by the sensible heat flux. The average sensi- ble heat flux （40.1 W/m2） was much larger than the average latent heat flux （14.5 W/m2）. Soil heat flux played an important role in the energy balance. The mean actual evaporation was 0.41 mm/d, and the cumulative actual evaporation was approximately 150 mm/a. The water vapor would transport downwardly and appear as dew con- densation water. The amount of precipitation determined the actual evaporation. The actual evaporation was sup- posed to be equal to the precipitation on the megadune and the precipitation was difficult to recharge the ground- water. Our study can provide a foundation for further research on land-atmosphere interactions in this area.

关键词： eddy covariance technology energy and water vapor fluxes precipitation evaporation

Mechanism on Carbon Vacancies in Polymeric Carbon Nitride for CO2 Photoreduction

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Chinese Journal of Structural Chemistry 2020年第12期39卷 2068-2076,2053页

作者： LIU Shao-Hua LI Yi DING kai-ning CHEN Wen-kai ZHANG Yong-Fan LIN Wei State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhou 350108China Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry Xiamen 361005China

Defect engineering has being regarded as one of the effective ways to regulate chemical and electronic structure of ***,our collaborative work has shown experimentally that carbon vacancy on polymeric carbon nitride(CV)can greatly improve the CO2 to CO conversion with a 45-fold improvement over the polymeric carbon nitride(***.,2019,58,1134).In order to clarify the detailed mechanism of promotion,we have systematically studied the electronic properties of CV and hydrogenated CV(CV+H)as well as the effective CO2 reduction reaction through density functional theory *** found that it is the synergistic effect for the CO2 reduction reaction in the CV systems,as the onset potentials of several CVs are much lower than that of the polymeric carbon *** particular,the onset potentials of CV1,CV2,and CV2+H are around 0.9~1.5 eV with a strong chemisorbed CO2 on *** with the analysis of the electronic properties,our results confirm that defect engineering increases the lifetime of photo-generated charges,improves photocatalytic activity,and promotes the CO2 reduction reaction on the defected polymeric carbon nitrides.

关键词： polymeric carbon nitride(PCN) carbon vacancy reaction mechanism CO2 reduction density functional theory(DFT)

Study on a probabilistic algorithm for the forming and 3D characterization of special-shaped surfaces under profile grinding

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Advances in Manufacturing 2024年第2期12卷 288-299页

作者： Zhao-Qing Zhang kai-ning Shi Yao-Yao Shi Yi-Hui Song Zhe He Ya-Song Pu School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an710072People’s Republic of China Key Laboratory of High Performance Manufacturing for Aero Engine(Northwestern Polytechnical University) Ministry of Industry and Information TechnologyXi’an710072People’s Republic of China Engineering Research Center of Advanced Manufacturing Technology for Aero Engine(Northwestern Polytechnical University) Ministry of EducationXi’an710072People’s Republic of China

Profile grinding is the most crucial method for the ultra-precision machining of special-shaped ***,profile grinding produces a unique machining profile,and many random factors in the machining process lead to complex surface *** this study,the structural and probabilistic characteristics of the profile grinding of a special-shaped surface were analyzed,and a probabilistic algorithm for the forming and 3D characterization of special-shaped surfaces under profile grinding was *** forming process of a GH738 blade tenon tooth surface was considered as an example to demonstrate the *** comparison results showed that the simulation results had similar surface characteristics to the measurement results,and the relative error range of the 3D roughness parameter was 0.21%–19.76%,indicating an accurate prediction and characterization of the complex special-shaped surface under the action of multiple factors.

关键词： Special-shaped surface Profile grinding Surface morphology 3D characterization

Eddy covariance measurements of water vapor and energy flux over a lake in the Badain Jaran Desert,China

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Journal of Arid Land 2018年第4期10卷 517-533页

作者： SUN Jie HU Wenfeng WANG Nai'ang ZHAO Liqiang AN Ran ning kai ZHANG Xunhe College of Earth and Environmental Sciences Center for Desert and Arid Region ResearchLanzhou JniversityLanzhou 730000China Center for Central Asian Atmosphere Science Research Urumqi 830002China Fuyang Normal University Fuyang 236037China

Exploring the surface energy exchange between atmosphere and water bodies is essential to gain a quantitative understanding of regional climate change, especially for the lakes in the desert. In this study, measurements of energy flux and water vapor were performed over a lake in the Badain Jaran Desert, China from March 2012 to March 2013. The studied lake had about a 2-month frozen period （December and January） and a 10-month open-water period （February-November）. Latent heat flux （LE） and sensible heat flux （Hs） acquired using the eddy covariance technique were argued by measurements of long＇wave and shortwave radiation. Both fluxes of longwave and shortwave radiation showed seasonal dynamics and daily fluctuations during the study period. The reflected solar radiation was much higher in winter than in other seasons. LE exhibited diurnal and seasonal variations. On a daily scale, LE was low in the morning and peaked in the afternoon. From spring （April） to winter （January）, the diurnal amplitude of LE decreased slowly. LE was the dominant heat flux throughout the year and consumed most of the energy from the lake. Generally speaking, LE was mostly affected by changes in the ambient wind speed, while Hs was primarily affected by the product of water-air temperature difference and wind speed. The diurnal LE and Hs were negatively correlated in the open-water period. The variations in Hs and LE over the lake were differed from those on the nearby land surface. The mean evaporation rate on the lake was about 4.0 mm/d over the entire year, and the cumulative annual evaporation rate was 1445 mm/a. The cumulative annual evaporation was 10 times larger than the cumulative annual precipitation. Furthermore, the average evaporation rates over the frozen period and open-water period were approximately 0.6 and 5.0 mm/d, respectively. These results can be used to analyze the water balance and quantify the source of lake water in the Badain Jaran Desert.

关键词： eddy covariance energy flux radiation evaporation precipitation lake Badain Jaran Desert