检索结果-南通市图书馆

Constitutive Equations for Flow Behavior of Powder-forged Fe-0.5C-2Cu Steel under Hot Compression

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2014年第3期21卷 389-395页

作者： biao guo Sui-cai ZHANG Chang-chun GE School of Materials Science and Engineering Southwest Jiaotong University Institute of Special Ceramics and Powder Metallurgy School of Materials Science and EngineeringUniversity of Science and Technology Beijing

To investigate the hot deformation behavior of powder-forged （P/F） Fe-0. 5C：-2Cu steel, the hot compres- sion tests were conducted at temperatures ranging from 900 to 1000 ℃ and strain rates from 0.1 to 10 s-1 using Gleeble-1500 thermal simulator. The true stress-true strain curves at different temperatures and strain rates of P/F steel were obtained. It is found that dynamic recovery only occurs as strain rate is 10 s 1 at 900 ℃, and the dynamic recrystallization is the main softening mechanism. The flow stress increases with decreasing temperature and increas- ing strain rate. The experimental data are employed to develop constitutive equations on the basis of the Arrhenius- type equation by introducing the strain with nonlinear fitting. The flow stresses prediel：ed by the proposed constitu- tive equations are in good agreement with the experimental values, and the correlation coefficient （R2） and the aver- age absolute relative error （AARE） are 0. 995 25 and 3.07% respectively. These results indicate the proposed consti- tutive equations can effectively describe the hot deformation behavior of the material.

关键词： powder-forged steel flow behavior constitutive equation

Exploring a new path of green and efficient utilization of sinter return fine to produce composite pellets

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第7期31卷 1610-1622页

作者： Yan-biao Chen Wen-guo Liu Hao guo Jing-song Wang Qing-guo Xue Hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China MCC Capital Engineering and Research Incorporation Limited Beijing 100176China

Efficient utilization of sinter return fine is an important measure to reduce cost,increase efficiency,save energy and reduce emission.A new path of green and efficient utilization of return fine was proposed to produce composite *** metallurgical properties of composite pellets under the condition of hydrogen-rich blast furnace were *** experimental results indicate that the coated concentrate was consolidated for the composite pellets through normal Fe_(2)O_(3) *** the surface of core return fine,the liquid phase formed due to its low-melting point,assimilated the adjacent concentrate,and then consolidated with the temperature *** with regular pellets,the com-pressive strength and reduction swelling index of composite pellets were decreased,but the reducibility index and softening-melting properties were *** addition,the reduction degradation index of composite pellets was sig-nificantly higher than that of ***,adding composite pellets was conducive to indirect reduction in blast furnace,reducing fuel ratio and improving production *** to the effect of the roasting system on the metallurgical properties,the roasting temperature and time were determined as 1250℃and 30 min,*** composite pellets can be produced under the traditional pelletizing process.

关键词： Sinter Return fine Composite pellet Roasting system Metallurgical property Hydrogen-rich blast furnace

Small-scale upper mantle convection and orogeny of Tianshan Mountains in China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2007年第8期50卷 1142-1149页

作者： LIU Jie LIU QiYuan guo biao SONG HuiZhen State Key Laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China

In this study, from the travel time data recorded in the Tianshan passive seismic array experiment, we present the P-wave velocity structure of the upper mantle down to 660 km along the Kuqa-Kuitun pro-file in terms of seismic tomography technique. Based on the P-wave velocity model, we derive the corresponding 2D upper mantle density model. The 2D small-scale convection of the upper mantle underneath the Tianshan Mountains in China driven by the density anomalies is simulated using the hybrid finite element method combining with the marker-in-cell technique. The main features of the upper mantle convection and the reciprocation between the convection and mountain building are in-vestigated. The results manifest that (1) in the upper mantle underneath the Junggar basin and North Tianshan exists a counterclockwise convection, which scale is ~ 500 km; (2) underneath the Tarim ba-sin and South Tianshan exists a clockwise northward convection, which is relatively weak; (3) the convective velocity at the top of the upper mantle underneath the Tianshan Mountains in China should not be less than 20 mm/a, while considering the dependent of convective velocity on the viscosity; (4) the northward extrusion of the Tarim block plays a key role in the Cenozoic Tianshan mountain building and the present-day tectonic deformation of the Tianshan range is related closely to the upper mantle convection; and (5) the northward subduction of the Tarim block does not influence obviously the up-per mantle convection.

关键词： Tianshan orogeny mantle convection orogeny finite element method marker-in-cell method

When a tree model meets texture baking:an approach for quality-preserving lightweight visualization in virtual 3D scene construction

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2023年第1期16卷 645-670页

作者： Chen Zhang biao He Renzhong guo Ding Ma School of Resource and Environmental Sciences Wuhan UniversityWuhanPeople’s Republic of China Research Institute for Smart Cities Shenzhen UniversityShenzhenPeople’s Republic of China

Three-dimensional(3D)high-fidelity surface models play an important role in urban scene ***,the data quantity of such models is large and places a tremendous burden on *** applications must balance the visual quality of the models with the rendering *** study provides a practical texture baking processing pipeline for generating 3D models to reduce the model complexity and preserve the visually pleasing ***,we apply a mesh simplification to the original model and use texture baking to create three types of baked textures,namely,a diffuse map,normal map and displacement *** simplified model with the baked textures has a pleasing visualization effect in a rendering ***,we discuss the influence of various factors in the process on the results,as well as the functional principles and characteristics of the baking *** proposed approach is very useful for real-time rendering with limited rendering hardware as no additional memory or computing capacity is required for properly preserving the relief details of the *** step in the pipeline is described in detail to facilitate the realization.

关键词： Texture baking tree modeling natural scene construction lightweight visualization 3D real scene

Meta-analysis of new intervention measures for preventing side effects of artificial joint replacement

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Orthopedics 2024年第5期15卷 469-476页

作者： Wei Jiang ting-biao Zhu Department of Orthopaedics Traditional Chinese Medicine Hospital of PingshanYibin 645350Sichuan ProvinceChina Department of Orthopaedics The First People's Hospital of QujingQujing 655099Yunnan ProvinceChina

BACKGROUND Intertrochanteric fracture of the femur occurs mostly among older people,and seriously affects daily life and quality of *** present,physical intervention,drug treatment,routine intervention and rehabilitation training are widely used for prevention of side effects,but it is still inconclusive which intervention has the best *** To compare the effects of new intervention measures for preventing side effects of artificial joint *** We searched the Chinese and English literatures for comparative studies on the prevention of side effects of new interventions for artificial joint replacement from July 2013 to June 2023 in China HowNet,PubMed,Wanfang,Weipu and other *** quality was evaluated by improved Jadad scoring standard,and the effects of different interventions on preventing different complications were analyzed by meta-analysis of evidence-based medicine with Review Manager 5.0 *** Ten articles,including 869 cases,were finally *** preventive effects of different interventions on the side effects of artificial joint replacement were studied,and valid data were *** were two articles on the preventive effects of drug intervention,four on comparison of the preventive effects of combined and single interventions,and three on the preventive effects of physical intervention,rehabilitation training and routine ***-analysis showed that the preventive effect of rivaroxaban was significantly better than low molecular weight heparin calcium[mean difference(MD)=-0.16,95%CI:-0.28 to-0.04,Pting deep vein thrombosis after artificial

关键词： Artificial joint replacement Venous thromboembolism Side effects Interventions Meta-analysis

H-infinity control for air-breathing hypersonic vehicle based on online simultaneous policy update algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Intelligent Computing and Cybernetics 2013年第2期6卷 126-143页

作者： Chao guo Huai-Ning Wu biao Luo Lei guo School of Automation Science and Electrical Engineering Beihang University(Beijing University of Aeronautics and Astronautics)BeijingChina

Purpose–The air-breathing hypersonic vehicle(AHV)includes intricate inherent coupling between the propulsion system and the airframe dynamics,which results in an intractable nonlinear system for the controller *** purpose of this paper is to propose an H1 control method for AHV based on the online simultaneous policy update algorithm(SPUA).Design/methodology/approach–Initially,the H1 state feedback control problem of the AHV is converted to the problem of solving the Hamilton-Jacobi-Isaacs(HJI)equation,which is notoriously difficult to solve both numerically and *** overcome this difficulty,the online SPUA is introduced to solve the HJI equation without requiring the accurate knowledge of the internal system ***,the online SPUA is implemented on the basis of an actor-critic structure,in which neural network(NN)is employed for approximating the cost function and a least-square method is used to calculate the NN weight ***–Simulation study on the AHV demonstrates the effectiveness of the proposed H1 control ***/value–The paper presents an interesting method for the H1 state feedback control design problem of the AHV based on online SPUA.

关键词： Programming and algorithm theory Controllers Design Nonlinear H1 control Air-breathing hypersonic vehicle Simultaneous policy update algorithm Hamilton-Jacobi-Isaacs equation Online

Metal organic framework(ZIF-67)-derived Co nanoparticles/Ndoped carbon nanotubes composites for electrochemical detecting of tert-butyl hydroquinone

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2021年第2期40卷 478-488页

作者： Jing Tang Sheng-biao Zheng Si-Xun Jiang Jie Li Teng guo Jia-Hao guo College of Chemistry and Material Engineering Anhui Science and Technology UniversityBengbu233030China

In this work,the framework of Co nanoparticles and nitrogen-doped carbon nanotubes(Co/NCNTs)derived from metal-organic frameworks(MOFs)through solid pyrolysis was successfully synthesized in the atmosphere of H2 and Ar *** Co/NCNTs composites exhibited superior electrocatalytic performance for tert-butyl hydroquinone(TBHQ)oxidation due to the synergistic effect between chemical composition and the specific structure of Co nanoparticles and nitrogen-doped carbon *** was found that the reaction underwent a quasi-reversible redox reaction with 37-fold higher anodic current for TBHQ at Co/NCNT-modified electrode when compared to bare glassy carbon electrode(GCE).In optimal condition,Co/NCNTs/GCE exhibited a linear range of0.05-80.00μmol·L^(-1) for detecting TBHQ,and the limit of detection(LOD)was estimated to be as low as10 nmol·L^(-1)(signal/noise of S/N=3).Moreover,the asobtained modified electrode was successfully used to assay the content of TBHQ in edible oil samples.

关键词： Nitrogen-doped carbon nanotubes(NCNTs) ZIF-67 Tert-butyl hydroquinone Modified electrode

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TURBULENT AIR-CUSHION-CASCADE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第2期14卷 41-44页

作者： guo, ting-ting Li, Shao-Hua Wang, guo-Hui Xu, Zhong Xi'an Jiaotong Univ. Xi'an 710049 China Northeast China Inst. of Electron. Jilin 132012 China

Experimental and numerical studies of air-cushion-cascade were conducted and described. The SIMPLE algorithm combined with the normal k-Ε turbulence model was adopted to simulate the air-phase flow. The experiment was carried out by an IFA 300 anemometer. The flow field was measured for different ratios of main-stream velocity to jet velocity, different numbers of gaps and a couple of gap widths. The contour of the air-cushion was obtained, and the numerical calculations gave a closed-form result. The results show that the air-cushion thickness would increase with the increase of the jet velocity, gap width and gap number mainly determined by the jet in the former half cascade. The possibility to achieve anti-erosion by the turbulent jet was examined and confirmed.

关键词： Anemometers Computer simulation Computer software Erosion Flow of fluids Turbulent flow

Quantitative attribution of Northern Hemisphere temperatures over the past 2000 years

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2023年第2期17卷 632-641页

作者： Feng SHI Mingfang ting Zhengtang guo Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044China Lamont-Doherty Earth Observatory Columbia UniversityPalisadesNY 10964USA University of Chinese Academy of Sciences Beijing 100049China

Quantitative assessment of natural internal variability and externally forced responses of Northern Hemisphere(NH)temperatures is necessary for understanding and attributing climate change signals during past warm and cold ***,it remains a challenge to distinguish the robust internally generated variability from the observed ***,largeensemble(70 member)simulations,Energy Balance Model simulation,temperature ensemble reconstruction,and three dominant external forcings(volcanic,solar,and greenhouse gas)were combined to estimate the internal variability of NH summer(June–August)temperatures over the past 2000 years(1–2000 CE).Results indicate that the Medieval Climate Anomaly was predominantly attributed to centennial-scale internal oscillation,accounting for an estimated 104%of the warming *** contrast,the Current Warm Period is influenced mainly by external forcing,contributing up to 90%of the warming *** temperature variability offsets cooling by volcanic eruptions during the Late Antique Little Ice *** findings have important implications for the attribution of past climate variability and improvement of future climate projections.

关键词： Common Era Internal variability Dark Ages Cold Period Medieval Climate Anomaly Current Warm Period