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Hot Deformation Behavior and Workability of(SiC_p + Mg_2B_2O_(5w))/6061 Al Hybrid and SiC_p/6061 Al Composites

Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 63-74页

作者： Mingliang wang Peipeng Jin Jinhui wang li Han Chuang Cui Qinghai Provincial Key Laboratory of New light Alloys Qinghai University

The hot deformation behavior of （3 vol% SiCp -4- 3 vol% Mg2B2Osw）/6061 A1 （W3P3） hybrid composite and 6 vol% SiCp/6061 A1 （P6） composite have been characterized in the temperature range of 300--450 ℃ and strain rate range of 0.0001-0.1 s-1 using isothermal constant true strain rate tests. The flow behavior and processing maps have been investigated using the corrected data to eliminate the effect of friction. Under the same deformation conditions, the compressive resistance of the singular composite remains superior to that of the hybrid composites. The processing map of W3P3 hybrid composite exhibits a single hot working domain at the temperature between 350 and 450 ℃ with strain rate between 0.0001 and 0.003 s-1 （domain A）. Two hot working domains exist for P6 composite：（i） 300-400 ℃/ 0.0001-0.003 s-1 （domain B1）; （ii） 380-450 ℃/0.01-0.1 s-1 （domain B2）. The processing maps also reveal the flow instability of the two composites, which is associated with whiskers breakage, whisker/matrix interfacial debonding, SiCp/ matrix interfacial decohesion, adiabatic shear bands or flow localization, and wedge cracking in the corresponding regions. The estimated apparent activation energies are about 224 kJ mo1-1 in domain A for W3P3 hybrid composite, 177 kJ mo1-1 in domain B1 and 263 kJ mo1-1 in domain B2 for P6 composite, respectively. These values are higher than that for self-diffusion in A1 （142 kJ mol-1）, suggesting that there is a significant contribution from the back stress caused by the presence of particles and/or whiskers in the matrix. The deformation mechanisms corresponding to domain B 1 and domain B2 are dislocation climb controlled creep and cross-slip for P6 composite, respectively. For W3P3 hybrid composite, the deformation mechanisms contain dislocation climb controlled creep and grain boundary sliding caused by DRX in domain A.

关键词： Hybrid composite Hot deformation Processing map Hot working Kinetic analysis

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Multiphase redistribution differences of polycyclic aromatic hydrocarbons （PAHs） between two successive sediment suspensions

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Frontiers of Environmental Science & Engineering 2016年第2期10卷 381-389页

作者： Rufeng li Chenghong FENG Dongxin wang Baohua li Zhenyao SHEN The Key Laboratory of Water and Sediment Sciences (Ministry of Education) School of Environment Beijing Normal University Beijing 100875 China

Successive sediment suspensions often happen in estuary, yet little research has probed into the difference in the release behaviors of organic compounds among different suspensions. This study took polycyclic aromatic hydrocarbons （PAHs） as typical organic contaminants and investigated the release behaviors between two successive suspensions with a particle entrainment simulator （PES）. Results showed that successive sediment suspensions lowered the concentration of dissolved PAHs in the overlying water via facilitating the re-adsorption of dissolved PAHs onto the suspended particles. Fast-release and slow-release periods of PAHs were successively observed in the both suspensions. The concentration changes of dissolved PAHs in the second suspension were generally similar with but hysteretic to those in the first suspension. More vigorous desorption and re-absorp- tion of PAHs were induced in the second suspension. Successive sediment suspensions obviously decreased the concentrations of mineral composition and organic matters in the overlying water, which significantly affects multi- phase distribution of PAHs.

关键词： sediment suspension PAHs multiphase dis-tribution distribution coefficients

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Heterogeneous Deformation Behaviors of an Inertia Friction Welded Ti_(2)AlNb Joint:an In‑situ Study

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Acta Metallurgica Sinica(English Letters) 2023年第4期36卷 611-622页

作者： Dingcong Cui Qingfeng Wu Feng Jin Chenbo Xu Mingxin wang Zhijun wang Junjie li Feng He Jinglong li Jincheng wang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

A defect-free Ti_(2)AlNb joint has been obtained by the inertia friction welding(IFW)*** weld zone(WZ)is composed of B2 grains refined by discontinuous dynamic recrystallization and enhanced by grain refinement *** the average microhardness decreases by about 30 HV from the WZ to the base ***-situ SEM analysis reveals that the heterogeneous structure of the joint causes strong strain partitioning during tensile *** microcrack initiation occurs at the interface of the initial B2 phases and B2/O *** to stress concentration,the multi-slip bands and cracks tend to generate in the heat-affected zone(HAZ),causing a premature fracture.

关键词： Ti_(2)AlNb alloy Inertia friction welding Microstructure Deformation behaviors

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Theoretical Studies on the Thermo- electric Properties of Tin-based Clathrates:Cs_8M_4Sn_(42)(M=Zn,Cd,Hg) and Cs_8Sn_(44)□_2

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Chinese Journal of Structural Chemistry 2013年第12期32卷 1793-1804页

作者： wang Peng WU li-Ming State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences University of Chinese Academy of Sciences

The site occupancies and thermoelectric properties of tin-based clathrates Cs8M4Sn44□2 （M = Zn, Cd, Hg） and CssSn44□2 were studied by the first principle calculations. We had provided an efficient way to probe the relationship between the crystalline structure and power factor. Detailed analyses indicated the p states of Sn at 16i and 24k sites together with the p states of M substitute contributed significantly to the maximum power factor, yet Cs atoms nearly did not. The dangling bonds of vacancies in Cs8Snn44□2 are also discussed. The power factors of p- and n-type CssMaSn42 and Cs8Sn44□2 at optimal temperature and carder concentration are predicted. Our results suggest that Cs8ZnaSn44□2 is a promising candidate at the 5.25 ×10^19 cm-3 hole carrier concentration as a high temperature thermoelectric material that is competitive to the state-of-art Ge-based clathrate thermoelectric materials.

关键词： the first principle thermoelectric boltzmann theory,clathrate tin electronic structure

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Hydrodynamics performance and tray efficiency analysis of the novel vertical spray packing tray

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2448-2454页

作者： Hongkang Zhao Lun li Baohua wang Dan Yu Qunsheng li State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China Sinopec Engineering Incorporation(SEI) Beijing 100101China College of Chinese Pharmacy Beijing University of Chinese Medicine and PharmacyBeijing 100102China

Column setup has been widely utilized in the petroleum and chemistry industries. However, with the fast progress of industries and the increasingly serious energy shortage, designing a new column setup with better performance and higher capacity becomes more urgent. In order to improve column's capacity and expand operating condition, a new type of column tray named novel vertical spray packing(NVSP) tray was designed and experimented. The performances of the novel tray, including pressure drop, weeping, entrainment and tray efficiency, were tested in a plexiglass column. In addition, performances of the novel tray were compared with that of the sieve tray and the Glitsch V1 valve tray. Based on the experiment data, the mathematical correlations of pressure drop, weeping and entrainment for the novel tray were established by regression analysis method. A fundamental model of dry pressure drop of the novel tray was promoted at the form of sum mode. The results indicate that the novel tray has wider operating condition and better performance.

关键词： Packing tray Hydrodynamics Tray efficiency High capacity

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What is the relationship between ecosystem services and urbanization? A case study of the mountainous areas in Southwest China

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Journal of Mountain Science 2019年第12期16卷 2867-2881页

作者： PENG li wang Xu-xi Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China College of Land and Resource China West Normal UniversityNanchong 637009China Institute of Jialing River Basin China West Normal UniversityNanchong 637009China

China is undergoing a rapid urbanization process,and urbanization will have a direct impact on regional ecosystems and affect regional ecosystem *** the mountainous counties in Southwestern China as the research object,this study reveals the spatial clustering characteristics of four typical ecosystem services(food production,soil conservation,water yield and carbon sequestration)as well as the trade-offs and synergies among ecosystem services in different urbanized *** the same time,piecewise linear regression is used to determine the threshold of the influence of urbanization on ecosystem *** results indicate that:1)There are spatial autocorrelations among the four typical ecosystem services;with strong clustering characteristics,the positive correlation types are"clustered"locally;and with significant spatial heterogeneity,the negative correlation types are scattered and mainly appear in the highly urbanized area.2)There are also remarkable differences in the relationship among various ecosystem services in different urbanized areas,and in particular,there are marked trade-offs between food production and carbon sequestration in the moderately urbanized area and the highly urbanized ***,there are synergies between them in the lowly urbanized area.3)With an increase in the compounded night light index(CNli),water yield,carbon sequestration,food production and overall ecosystem services values present an increasing-decreasing trend,the soil conservation function value shows a decreasing-increasing *** response of water yield,carbon sequestration,food production,and overall ecosystem services to the compounded night light index(CNli)has a threshold of 1.2642,1.4833,1.3388,1.5146 and 1.2237,*** on the detected relationships between urbanization and ecosystem services,this study provides a theoretical reference for the selection of urbanization development models in key ecological functional areas.

关键词： Ecosystem services Urbanization Spatial clustering pattern Trade-offs/synergies Southwestern China

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Data-driven consensus control of fully distributed event-triggered multi-agent systems

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Science China(Information Sciences) 2023年第5期66卷 147-161页

作者： Yifei li Xin wang Jian SUN Gang wang Jie CHEN School of Automation Beijing Institute of Technology The State Key Lab of Autonomous Intelligent Unmanned Systems Beijing Institute of Technology Beijing Institute of Technology Chongqing Innovation Center Department of Control Science and Engineering Tongji University

This study investigates the consensus control issue in discrete-time linear multi-agent systems(MASs) using data-driven control under undirected communication networks. To alleviate the communication burden, an adaptive event-triggered control strategy involving only local information is proposed and a model-based stability condition is derived that guarantees the asymptotic consensus of MASs. Furthermore,a data-based consensus condition for unknown MASs is established by combining a data-based system representation with the model-based stability condition, using only pre-collected noisy input-state data instead of the accurate system information a priori. Specifically, both model-based and data-driven event-triggered controllers can be utilized without requiring any global information. The validity and correctness of the controllers and associated theoretical results are demonstrated via numerical simulations.

关键词： distributed control event-triggered control data-driven control discrete-time MASs

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Vaporization model of MgCl2-CaCl2 binary melts in fluidized bed

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Chinese Journal of Chemical Engineering 2017年第1期25卷 123-129页

作者： Qiao wang Qingshan Zhu Chuanlin Fan Zhen wang Hongzhong li State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The present study investigated the vaporization kinetics of MgCl_2,CaCl_2 and their binary melts in a fluidized bed at1073-1273 K,and developed a vaporization model for the binary melts to explore the possibility of achieving enhanced vaporization rate for the feedstock containing CaO greater than 0.2 wt%.The vaporization rate constant of MgCl_2 is more than seven times than that of CaCl_2 at 1273 *** vaporization rate of the binary melt was significantly affected by the composition,a small quantity of CaCl_2 can remarkably deteriorate the overall vaporization *** results coincide well with the numerical simulation by the vaporization model which regards the evolution of vaporization rate with melts composition.A correlation between the necessary operation temperature and the CaO/(CaO + MgO) of the feedstock was *** reveal that a similar vaporization rate for 0.2 wt%-0.4 wt%CaO content feedstock with 0.2 wt%could be achieved at lower than 1365 K.

关键词： MgCl2 CaCl2 Binary melts Vaporization kinetics Kinetics model

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Manufacturing a TiAl alloy by high-energy ball milling and subsequent reactive sintering

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Rare Metals 2006年第1期25卷 21-26页

作者： QU Shengguan li Xiaoqiang li Yuanyuan HU lianxi wang Erde College of Mechanical Engineering South China University of Technology Guangzhou 510640 China College of Materials Science ＆ Engineering Harbin Institute of Technology Harbin 150001 China

A TiAl alloy was fabricated by high-energy ball milling and subsequent reactive sintering from the mixed powders of Ti and Al. High-energy ball milling produced a kind of particular composite powders with an extremely fine altemative Ti and Al lamella structure. The composite powders not only possessed good consolidation and densification characteristics, but also resulted in the augment of nucleation rate of α and γ titanium aluminides during solid-phase reactive sintering After a series of processing, pressing, degassing, extrusion, and sintering, the resultant TiAl alloy presented high relative density and refined grain sizes of （α2 ＋ γ） lamella and γ phases. The compressive yield strength of the sintered TiAl reached 600 MPa at 800℃.

关键词： TiAl alloy high-energy ball milling reactive sintering

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Robust route to H_(2)O_(2)and H_(2)via intermediate water splitting enabled by capitalizing on minimum vanadium-doped piezocatalysts

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Nano Research 2022年第9期15卷 7986-7993页

作者： Yuekun li li li Fangyan liu Biao wang Feng Gao Chuan liu Jingyun Fang Feng huang Zhang lin Mengye wang School of Materials Sun Yat-Sen UniversityShenzhen 518107.State Key Laboratory of Optoelectronic Materials and TechnologiesSun Yat-Sen UniversityGuangzhou 510275China School of Environment and Energy Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and RecyclingSouth China University of TechnologyGuangzhou 510006China School of Metallurgy and Environment Central South UniversityChangsha 410083China Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and EngineeringSun Yat-Sen UniversityGuangzhou 510275China The Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information TechnologySun Yat-Sen UniversityGuangzhou 510275China

H_(2)O_(2)is an environmentally friendly chemical for a wide range of water *** industrial production of H_(2)O_(2)is an anthraquinone oxidation process,which,however,consumes extensive energy and produces *** we report a green and sustainable piezocatalytic intermediate water splitting process to simultaneously obtain H_(2)O_(2)and H_(2)using single crystal vanadium(V)-doped NaNbO_(3)(V-NaNbO_(3))nanocubes as *** introduction of V improves the specific surface area and active sites of NaNbO_(3).Notably,V-NaNbO_(3)piezocatalysts of 10 mg exhibit 3.1-fold higher piezocatalytic efficiency than the same catalysts of 50 mg,as more piezocatalysts lead to higher probability of *** aggregation causes reducing active sites and decreased built-in electric field due to the neutralization between different ***,piezocatalytic H_(2)O_(2)and H_(2)production rates of V-NaNbO_(3)(10 mol%)nanocubes(102.6 and 346.2μmol·g^(−1)·h^(−1),respectively)are increased by 2.2 and 4.6 times compared to the as-prepared pristine NaNbO_(3)counterparts,*** improved catalytic efficiency is attributed to the promoted piezo-response and more active sites of NaNbO_(3)catalysts after V doping,as uncovered by piezoresponse force microscopy(PFM)and density functional theory(DFT)*** importantly,our DFT results illustrate that inducing V could reduce the dynamic barrier of water dissociation over NaNbO_(3),thus enhancing the yield of H_(2)O_(2)and H_(2).This facile yet robust piezocatalytic route using minimal amounts of catalysts to obtain H_(2)O_(2)and H_(2)may stand out as a promising candidate for environmental applications and water splitting.

关键词： water splitting H_(2)evolution H_(2)O_(2)production piezocatalysis vanadium-doped NaNbO_(3)

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