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Macro and Micro Behaviors of Low Alloyed TRIP780 Steel with Different Biaxial Proportional Loading

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Journal of Iron and Steel Research International 2015年第3期22卷 256-263页

作者： Hong-yang LI Yan-jing ZHANG Wen-jun ZHAO Zhi-fei GU Xian-chao LI Jin-long MA School of Materials Science and Engineering Beijing Institute of Technology National Key Laboratory of Science and Technology on Materials under Shock and Impact Beijing Institute of Technology Inner Mongolia First machinery(Group) co. Ltd.

To investigate the macro and micro behaviors of TRIP （transformation induced plasticity） steel under biaxial loading, experiment and finite element simulation were carried out for TRIP780 steel under proportional biaxial tension with displacement ratio of 1 ： 1, 2 ： 1, 3 ： 1 and 4 ： 1, respectively. The results show that cruciform specimens of TRIP780 steel fractured under proportional biaxial stretching when effective strain was about L 5 %, and fracture was always generated on the cross arm or cross links. During biaxial tension, stress and strain co.ponents in x and y directions of the center of the samples have the same nonlinear developing tendency, decreasing in one direction and increasing in another direction. Equal biaxial stretching stress state was helpful for retained austenite-martensite transformation than the other biaxial stress state. With increasing displacement ratio （DR） from 1 ： 1 to 4 ： 1, co.responding stress distributed unevenly on the yield ellipse from 30° to 60° in the first quadrant of stress space and co.responding retained austenite volume fraction distributed symmetrically in bow tie format.

关键词： TRIP steel retained austenite biaxial loading yield ellipse

Processing Technology and Mechanical Properties of Die-Cast Magnesium Alloy AZ91D

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Tsinghua Science and Technology 2004年第5期9卷 612-616页

作者：刘艳改刘文辉熊守美柳百成王罡 MATSUMOTO Yoshihide MURAKAMI Masayuki Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Toyo machinery and Metal co. Ltd.Hyogo 674-0091Japan

The mechanical properties of magnesium die-casting co.ponents can be improved with im- proved die-casting processing technology. An orthogonal experiment with four factors and three levels (Lq, 34) was used to evaluate the effect of various die-casting processing parameters on the quality and me- chanical properties of an AZ91D magnesium alloy cylinder head co.er co.ponent. The results show that the injection speed and casting and die temperatures all influence the co.ponent quality, with the influence of the casting pressure being the smallest. The injection speed and casting pressure are the two most im- portant factors influencing the tensile strength. The best die-casting parameters for the magnesium alloy cyl- inder head co.er co.ponent were determined to be a casting temperature of 660℃, a die temperature of 200℃, an injection speed of 70 mgs?1, and a casting pressure of 65 MPa. The porosity is one of the most important parameters influencing the casting strength.

关键词： AZ91D die casting magnesium process parameters mechanical properties

A subspace based method for modelling building’s thermal dynamic in district heating system and parameter extrapolation verification

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Building Simulation 2023年第11期16卷 2145-2158页

作者： Junfeng Zhang Lanbin Liu Yameng Liu University of Science and Technology beijing 30 Xueyuan RoadBeijing100083China beijing Nuanliu Technology co. Ltd.Beijing100083China

The district heating system(DHS)co.sumes a lot of energy in winter,and its co.trol accuracy needs to be improved *** apply advanced process co.trol(APC)in DHS,the thermal dynamic model of the existing buildings is *** paper uses the subspace method which is a data-driven approach for modelling the thermal dynamics of the *** model’s performance is analyzed using the co.lected data,and the differences co.pared to the classical methods are also *** method reduces the RMSE by about 20%co.pared with the ARX model for the same ***,the analysis of the training residuals indicates that the estimate of periodic intra-building disturbance can be obtained by minimizing the training *** introducing the estimated disturbance function,the RMSE on the test set is further reduced by 26%.At the end of the article,a simple parameter extrapolation experiment is co.ducted,and the result shows that the parameters can be extrapolated to other buildings without large errors.

关键词： modelling district heating system state-space ARX thermal dynamics

The Fuxing: The China Standard EMU

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Engineering 2020年第3期6卷 227-233页

作者： Yanhui Qi Li Zhou China State Railway Group co. Ltd.Beijing 100844China China Academy of Railway Sciences co. Ltd.Beijing 100081China

*** overview Since the first high-speed railway(HSR)intercity line was built between beijing and Tianjin in 2008,China’s HSRs have developed *** a short span of ten years,successive HSRs have entered operation between Zhengzhou and Xi’an,beijing and Shanghai,beijing and Guangzhou,Lanzhou and Urumqi,and around Hainan *** the end of 2018,the HSR route length in China exceeded 29000 km,acco.nting for over two thirds of the world’s total.

关键词： successive Tianjin railway

Synthesis and Characterization of Sulfonated Polyphosphazene-graft-Polystyrene co.olymers for Proton Exchange Membranes

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Chinese Journal of Polymer Science 2014年第2期32卷 151-162页

作者： Min-lan He Hu-lin Xu Yan Dong Jia-hong Xiao Peng Liu Feng-yan Fu Saghir Hussain Shu-zhen Zhang Chao-jun Jing Qun Yu 朱长进 Department of Applied Chemistry Beijing Institute of Technology beijing Qintian Science & Technology Development co. Ltd beijing Institute of Transfusion Medicine

A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） co.olymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length co.ld be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS co.olymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS co.olymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and co.siderable proton co.ductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microsco.y showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated co.olymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.

关键词： Atom transfer radical polymerization Direct methanol fuel cell Graft co.olymers Proton exchange membrane Polyphosphazenes.

Preparation and Rheological Characterization of Long Chain Branching Polyglyco.ide

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Chinese Journal of Polymer Science 2024年第8期42卷 1177-1184页

作者： Wei-Lin Liu Ming-Fu Lyu Heng-Yuan Zhang Jian-Ye Liu Shi-Jun Zhang beijing University of Chemical Technology Beijing 100029China SINOPEC(beijing)Research Institute of Chemical Industry co. Ltd.Beijing 100013China

The long chain branching(LCB)polyglyco.ide(PGA)was successfully prepared by the successive reactions of the terminal hydroxyl groups of PGA with triglycidyl isocyanurate(TGIC)and pyromellitic dianhydride(PMDA).The influence of LCB produced by functional group reaction on rheological and crystallization behavior was studied and discussed through linear rheology,uniaxial elongation and DSC(differential scanning calorimetry).The much higher visco.ity and the more notable strain hardening behavior of modified PGA indicates the LCB with high degree of entanglements are *** melt strength of PGA is finally improved greatly and can make su re that the supercritical co.(2)foaming can be carried out successfully.

关键词： Polyglyco.ide(PGA) Long chain branching(LCB) Rheology

Identification and nonlinear model predictive co.trol of MIMO Hammerstein system with co.straints

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Journal of Central South University 2017年第2期24卷 448-458页

作者：李大字贾元昕李全善靳其兵 Department of Automation Beijing University of Chemical Technology Beijing 100029 China beijing Century Robust Technology co. Ltd. Beijing 100020 China

This work is co.cerned with identification and nonlinear predictive co.trol method for MIMO Hammerstein systems with co.straints. Firstly, an identification method based on steady-state responses and sub-model method is introduced to MIMO Hammerstein system. A modified version of artificial bee co.ony algorithm is proposed to improve the prediction ability of Hammerstein model. Next, a co.putationally efficient nonlinear model predictive co.trol algorithm(MGPC) is developed to deal with co.strained problem of MIMO system. The identification process and performance of MGPC are shown. Numerical results about a polymerization reactor validate the effectiveness of the proposed method and the co.parisons show that MGPC has a better performance than QDMC and basic GPC.

关键词： model predictive co.trol system identification co.strained systems Hammerstein model polymerization reactor artificial bee co.ony algorithm

A reliable and co.sistent production technology for high volume co.pacted graphite iron castings

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China Foundry 2014年第4期11卷 339-350页

作者： Liu Jincheng SinterCast Trading (beijing) co. Ltd.

The demands for improved engine performance,fuel eco.omy,durability,and lower emissions provide a co.tinual challenge for engine *** use of co.pacted Graphite Iron(CGI)has been established for successful high volume series production in the passenger vehicle,co.mercial vehicle and industrial power sectors over the last *** increased demand for CGI engine co.ponents provides new opportunities for the cast iron foundry industry to establish efficient and robust CGI volume production processes,in China and *** production window range for stable CGI is narrow and co.stantly ***,any one step single addition of magnesium alloy and the inoculant cannot ensure a reliable and co.sistent production process for co.plicated CGI engine *** present paper introduces the SinterCast thermal analysis process co.trol system that provides for the co.sistent production of CGI with low nodularity and reduced porosity,without risking the formation of flake *** technology is currently being used in high volume Chinese foundry *** Chinese foundry industry can develop co.plicated high demand CGI engine castings with the proper process co.trol technology.

关键词： co.pacted graphite iron nodularity modification inoculation carbon equivalent production technology

Effect of pre-annealing treatment on the microstructure and mechanical properties of extruded Al–Zn–Mg–Cu alloy bars

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International Journal of Minerals,Metallurgy and Materials 2017年第11期24卷 1284-1292页

作者： Zhi-hao Zhang Jie Xue Yan-bin Jiang Feng Jin Institute for Advanced Materials and Technology University of Science and Technology Beijing beijing Hangxing Machine Manufacture co. Ltd

Taking extruded Al–Zn–Mg–Cu alloy(7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350°C for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430°C after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.

关键词： aluminum alloy hot extrusion pre-annealing treatment microstructure mechanical properties