检索结果-南通市图书馆

Effect of erbium doping on phase composition, mechanical and thermal properties of ZrO_(2)-based ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第10期40卷 1628-1634页

作者： zheng cao Shengli An Xiwen Song School of Metallurgy and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Inner Mongolia Key Laboratory of Advanced Ceramic Materials and Devices Inner Mongolia University of Science and TechnologyBaotou O14010China School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010China

Er_(x)Ti_(0.1)Zr_(0.9-x)O_(2-1.5 x)(x=0.04,0.05,0.06,0.07,0.08) ceramics were synthesized by a solid-state reaction *** influence of the Er^(3+) addition on the phase composition,Vickers hardness,fracture toughness,and thermal conductivity of this ceramic material was *** X-ray diffraction results reveal that the c-ZrO_(2) content increases from 1.85 vol% to 33.89 vol%,and the percentage of t-ZrO_(2) decreases from 98.15 vol% to 66.11 vol% with the increase in Er^(3+) content from 4 mol% to 8 mol%.Moreover,the addition of Er^(3+) is beneficial to the volume expansion of the unit *** the same time,the incorporation of Er^(3+) weakens the coordination of oxygen ions around the metal cations,resulting in a corresponding decrease in the tetragonality of the t-ZrO_(2).The Vickers hardness and fracture toughness of the Er_(x)Ti_(0.1)Zr_(0.9-x)O_(2-1.5)_(x) ceramics show increasing and decreasing trends,*** thermal conductivity has a significant decline due to point defects caused by the Er^(3+) *** 8 ETZ ceramic exhibits the highest Vickers hardness(12.7 GPa),the lowest fracture toughness(7.6 MPa·m^(1/2)),and the lowest average thermal conductivity(1.85 W/(m·K)) in the temperature range of 200-1000℃.All of the above properties are higher than those of the Y_(2)O_(3)-stabilized ZrO_(2) ceramic.

关键词： Er_(2)O_(3) Phase composition Vickers hardness Fracture toughness Thermal conductivity Rare earths

Dual-negative-objective Coordinated Control of Brushless Doubly Fed Induction Generator under Unbalanced Grid Voltage

在线全文

学校读者我要写书评

暂无评论

CES Transactions on Electrical Machines and Systems 2024年第3期8卷 347-355页

作者： Ming Cheng zheng cao Xiaoming Yan School of Electrical Engineering Southeast UniversityNanjing 210096China School of Electrical and Automation Engineering Nanjing Normal University Nanjing 210023China

This article proposes a dual-negative-objective coordinated control strategy for brushless doubly fed induction generator(BDFIG)based wind power generation system under unbalanced grid *** alleviate the mechanical stress and impaction on rotating shaft,the negative control objective(NCO)of machine side converter(MSC)is set to suppress the ripple of electromagnetic *** the NCO of grid side converter(GSC)is selected to suppress the oscillation of total output active power or the unbalanced degree of total output current for BDFIG generation *** comparison with traditional single converter control scheme of the MSC or GSC,dual NCOs can be satisfied at the same time due to the enlarged freedom degree in the proposed improved coordinated control system for back-toback *** effectiveness of proposed control strategy is validated by simulation and experimental results on a dual-cagerotor BDFIG(DCR-BDFIG)prototype.

关键词： Brushless doubly fed induction generator Dual-negative-objective Freedom degree Unbalanced grid voltage

Effect of work hardening discrepancy on strengthening of laminated Cu/CuZn alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第8期103卷 67-72页

作者： zheng cao Zhao Cheng Wei Xu Lei Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

To clarify the work hardening discrepancy effect on the strengthening of laminated metals,we designed two laminated Cu/Cu4Zn and Cu/Cu32Zn samples with different layer ***/Cu4Zn has larger work hardening discrepancy between two constituent layers relative to Cu/Cu32Zn,but the yield strengths of two Cu Zn constituents are *** tensile results suggest Cu/Cu4Zn with larger work hardening discrepancy exhibits a significant strengthening at early deformation stage while Cu/Cu32Zn possesses a better *** underlying mechanisms for the strengthening effect are attributed to more geometrically necessary dislocations accumulated at interfaces and severer strain localization due to the larger work hardening discrepancy.

关键词： Laminated Cu/Cu alloys Work hardening Strengthening Interfacial affected zone Strain localization

Heteroscedasticity and/or Autocorrelation Checks in Longitudinal Nonlinear Models with Elliptical and AR(1) Errors

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2012年第1期28卷 49-62页

作者： Chun-zheng cao Jin-Guan LIN College of Math&Physics Nanjing University of Information Science&TechnologyNanjing 210044China Department of Mathematics Southeast UniversityNanjing 210096China

The aim of this paper is to study the tests for variance heterogeneity and/or autocorrelation in nonlinear regression models with elliptical and AR（1） errors. The elliptical class includes several symmetric multivariate distributions such as normal, Student-S, power exponential, among others. Several diagnostic tests using score statistics and their adjustment are constructed. The asymptotic properties, including asymptotic chi-squave and approximate powers under local alternatives of the score statistics, are studied. The properties of test statistics are investigated through Monte Carlo simulations. A data set previously analyzed under normal errors is reanalyzed under elliptical models to illustrate our test methods.

关键词： autocorrelation elliptical distributions heteroscedasticity longitudinal data nonlinear model,score test

Fluid-solid coupling numerical simulation of micro-disturbance grouting treatment for excessive deformation of shield tunnel

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第6期19卷 87-100页

作者： Yanjie Zhang zheng cao Chun Liu Hongwei Huang College of Civil Engineering and Architecture Henan University of TechnologyZhengzhou 450001China School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

Micro-disturbance grouting is a recovery technique to reduce the excessive deformation of operational shield tunnels in urban *** grout mass behaves as a fluid in the ground before hardening to form a grout–soil mixture,which highlights the necessity of using fluid–solid coupling method in the simulation of grouting *** a discrete element modeling environment,this paper proposes a novel fluid-solid coupling method based on the pore density flow *** demonstrate the effectiveness of this method,it is applied to numerical simulation of micro-disturbance grouting process for treatment of large transverse deformation of a shield tunnel in Shanghai Metro,*** simulation results reveal the mechanism of recovering tunnel convergence by micro-disturbance grouting in terms of compaction and fracture of soil,energy analysis during grouting,and mechanical response of soil-tunnel interaction ***,the influence of the three main grouting parameters(i.e.,grouting pressure,grouting distance,and grouting height)on tunnel deformation recovery efficiency is evaluated through parametric *** order to efficiently recover large transverse deformation of shield tunnel in Shanghai Metro,it is suggested that the grouting pressure should be about 0.55 MPa,the grouting height should be in the range of 6.2–7.0 m,and the grouting distance should be in the range of 3.0–3.6 *** results provide a valuable reference for grouting treatment projects of over-deformed shield tunnel in soft soil areas.

关键词： Fluid-solid coupling Discrete element method Pore density flow Micro-disturbance grouting Soil-tunnel interaction

Integration of energy recovery network including recycling residual pressure energy with pinch technology

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2017年第4期25卷 453-462页

作者： Jianqiang Deng zheng cao Dongbo Zhang Xiao Feng School of Chemical Engineering and Technology Xi'an Jiaotong University Shaanxi Coal and Chemical Technology Institute Co. Ltd

Work exchange is a promising innovative technology in recovering residual pressure energy. However, at the systematic level, the comprehensive utilization of different energy resources in an energy system has become an issue of concern. In this work, a systematic approach is proposed, one that successively integrates heat, work and adjusts operation parameters. A detailed procedure for building a heat-work coupling transfer network is provided. The synthesis mainly consists of constructing a work exchange sub-network with pinch analysis based on positive displacement type work exchangers. Simultaneously, another kind of sub-network based on turbine-type work exchangers is built as a schematic comparison. The influence of applying a positive displacement work exchanger on the system is investigated. Finally, as a case study, a renovation design of a typical rectisol process in the coal-water slurry gasification section of an ammonia plant is presented. The results show that the added work exchanger has little impact on the existing heat exchange sub-network. Moreover,extra pressure energy is recovered by coupling the transfer network. It is concluded that the heat-work systematic design is a promising and powerful method to use energy more efficiently.

关键词： matching gasification successively slurry constructing exchanger recycling turbine powerful innovative

Mechanical and magnetic properties of copper dispersed ferrum films under heat treatment

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2014年第6期33卷 641-645页

作者： Guma Yeli zheng-cao Li Xiao-Yi Yu zheng-Jun Zhang Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University China National Offshore Oil Corporation Research Institute

The Cu-containing steels are widely used for nuclear pressure vessel materials because of their good performance under high pressure and high temperature. In this article, magnetron sputtering was used to prepare iron films with various Cu contents. The samples were annealed at temperature range of 300–500 °C, and the structural,mechanical, and magnetic properties were studied. The results show that both hardness and modulus change along with copper content and annealing temperature. The change in coercivity after annealing is similar to that of hardness. The crystal grain growth in matrix ferrum and Cu precipitation during annealing influences both the mechanical and magnetic properties.

关键词： Ferrum Copper precipitates Magnetron sputtering Thermal properties

RECENT PROGRESS ON PARTICLE IMAGE VELOCIMETRY IN CHINA

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第1期18卷 11-19页

作者： LIU Ying-zheng cao Zhao-min School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

An up-to-date review of recent progress on Particle Image Velocimetry （PIV） instrumentations was extensively presented in the paper. Around 80 literatures were referenced. Among various aspects of PIV advances, the present concern was mainly placed on progresses of advanced algorithms and microscopic PIV. Attention was specifically directed toward contributions of domestic researchers to these subjects, which were stressed throughout the discussion. In addition, diverse applications of PIV technology in China, e. g., turbulence measurement, hydrodynamics, rotating flows, two-phase flows, were specifically summarized.

关键词： Particle Image Velocimetry (PIV) algorithm microscopic PIV review

Spatial and Temporal Dynamics of Surface Water in China from the 1980s to 2015 Based on Remote Sensing Monitoring

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2022年第1期32卷 174-188页

作者： SONG Song cao zheng WU Zhifeng CHUAI Xiaowei School of Geography and Remote Sensing Guangzhou UniversityGuangzhou 510006China Southern Marine Science and Engineering Guangdong Laboratoty(Guangzhou) Guangzhou 511458China School of Geographic and Oceanographic Science Nanjing UniversityNanjing 210046China

Climate change and human interference play significant roles on dynamic of water body abundance,and drive related hydrological,biochemical and social/economic *** and monitoring surface water area with high resolution multi-temporal satellite imagery provide new perspective to evaluate the dynamics of surface water area,especially in continental and global *** this study,based on the Landsat images from 1980 s to 2015,we surveyed the spatial and temporal variation of surface water area,including rivers,lakes and reservoirs,in 10-yr temporal slice across ***,the driving forces of the variation has been identified to reveal the interaction of water bodies and the changing *** results show that,the water surface area expanded over all three decades with strong spatial and temporal difference,despite the drier and warmer climate background;although lakes comprise the largest portion of the surface water area,the highest contributor of surface water expansion was new constructed reservoir located in the densely populated region;climatic parameters alteration,like precipitation and temperature,resulted in the water surface expansion in the northwestern basin by growing water input linked with rain and glacier melting;in the rest part of China,rise of water surface area was predominately attributed to human relocation of water resource,which yielded more new water storage area than the disappeared water body caused by less precipitation and stronger *** conclusions highlight the integrative water resource management,especially in water conservation and restoration.

关键词： temporal dynamics spatial variation surface water area expansion driving forces