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Currents induced by vertical varied radiation stress in standing waves and evolution of the bed composed of fine sediments

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International Journal of Sediment Research 2009年第2期24卷 214-226页

作者： Jing-Xin ZHANG1 and Hua LIU2. Lecturer,Department of engineering Mechanics,school of Naval Architecture,Ocean and Civil engineering,{3. jiao tong University,800 Dongchuan Road,{3. 2.02.0,china 2.Department of engineering Mechanics,school of Naval Architecture,Ocean and Civil engineering,{3. jiao tong University,800 Dongchuan Road,{3. 2.02.0,china Department of engineering Mechanics School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China

This paper extends the conventional concept of radiation stress(Longuet-Higgins and Stewart,1964) in progressive water waves to standing waves,so that its vertical profile could be defined and calculated in a new technical way. The hydrodynamic numerical model being coupled with the vertically varying radiation stress in standing waves is used to simulate the currents being induced by standing waves in the vertical section. Numerical modeling of suspended sediment transport is then carried out to simulate the evolution of the bed composed of fine sediments by the currents. The scour and deposition patterns simulated are in qualitative agreement with prior laboratory and field observations.

关键词： Standing wave Vertical variation in radiation stress Scour pattern Suspended sediment

Effect of slow monomer addition on molecular parameters of hyperbranched polymers synthesized in the presence of multifunctional core molecules

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science china Chemistry 2010年第4期53卷 891-897页

作者： ZHOU ZhiPing1, Jia ZhengWei1 & YAN DeYue2.1school of Materials science and {2., Jiangsu University, Zhenjiang 2.2.13.{3. 2.tate Key Laboratory of Metal Matrix Composites, shanghai jiao tong University, shanghai 2.02.0,{3. school of Materials science and {2. Jiangsu University Zhenjiang China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai China

This study develops the kinetics for the slow monomer addition technique in the synthesis of hyperbranched polymers. Taking the conversion of monomer (x) as a variable, we derived the analytic expressions of molecular size distribution function, average degree of polymerization, polydispersity index and degree of branching. These expressions are not only amenable to the polymerization with high monomer conversion, but also appropriate to describe the whole polymerization process. Comparison with the one-pot polymerization indicates that the slow monomer addition technique improves the molecular weight distribution and increases the degree of branching for the products obtained.

关键词： hyperbranched polymer kinetics molecular weight distribution polydispersity degree of branching

Strain Softening and Hardening Behavior in AZ61 Magnesium Alloy

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Journal of Materials science & Technology 2004年第6期20卷 691-693页

作者： Haitao ZHOU, Liufa LIU, Qudong WANG, Da LU, Xiaoqin ZENG and Wenjiang DINGNational engineering Research Center of Light Alloys Net Forming, school of Materials {2. and engineering, shanghai jiao tong University, shanghai 2.0030, china Ctr. of Light Alloys Net Forming Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

The deformation behavior of AZ61 Mg alloy during hot deformation has been investigated in wide temperature and strain rate range by a Gleeble simulator. Specimens are deformed in compression in the temperature range of 52.0}673.K and at strain rates of 0.001-1 s-1. It is found that the flow curves exhibit a peak and then decrease towards steady-state of classical DRX, which decrease with rising temperature and decreasing strain rate. The deformation behavior of the specimens can be attributed to the occurrence of strain hardening and softening. As stress decreases, the strain hardening rate declines at a fast rate when temperature rises or strain rate decreases. The shapes of θ-σ curves indicate some important features such as subgrain formation, the criticai stress, the peak stress and steady stress. The onset of DRX can be determined by the point of inflection on θ-σ or Inθ-σ curves.

关键词： AZ61 Mg alloy Recrystallization Strain hardening and softening

Nucleation Mechanism for Bainite

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Journal of Materials science & Technology 2002年第1期18卷 1-2页

作者： Xi ZHANG, Xuejun JIN and T.Y.Hsu(Xu Zuyao)school of Materials science and {2., {3. jiao tong University, shanghai 2.0030, china [ Manuscript received October 8, 2.01] shanghai jiao {2. Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China

Based on the experimental results that solute-depleted zone was observed in Cu-2.Zn-4AI (mass fraction) at 52.0}K, AG is calculated as a positive according to the thermodynamic criteria for the spinodal decomposition of a ternary systems. So, the solute-depleted zone cannot be formed by spinodal decomposition. Dislocation density required by the formation of solute-depleted zone is estimated greater than 7.89×109 cm-2. according to the segregation of solute atoms around dislocations, which is not consistent with the practical situation for the alloy at 52.0}K. Associated with the internal friction experimental fact that internal friction peaks appear within the incubation for bainitic transformation in Cu-Zn-AI alloy, the equilibrium temperature, TO, is evaluated as 43. K for solute-depleted Cu-2.Zn-3.4AI, which is lower than the experimental temperature 52.0}K. Thus, nucleation by shear mechanism is impossible in this circumstance. Therefore, it is concluded that, like bainite in steels and Ag-Cd, bainite in Cu-Zn-AI alloys nucleates by diffusional mechanism, just implied by the experimental existence of solute-depleted zone.

关键词： Bainitic transformation Prebainitic phenomenon Solute-depleted zone Diffusion Nucleation

Fabrication and application of nanocrystalline diamond films

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金刚石与磨料磨具工程 2008年第S1期28卷 97-103页

作者： Sun Fanghong~1,Zhang Zhiming~2.Shen Hesheng~2.Guo Songshou~2.(1.school of Mechanical engineering,{2. {3. tong University,{2. 2.02.0,china 2.Research Institute of Micro/Nanometer science & Technology, {2. {3. tong University,{2. 2.02.0,china)

Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H2.Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） *** evidence of nanocrystallinity,smooth... 详细信息

Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H2./sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） *** evidence of nanocrystallinity,smoothness and purity was obtained by characterizing the sample with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy,atomic force microscopy （AFM ）,and field emission transmission electron microscopy（FE-TEM ）.The results show that nanocrystalline diamond films consists of nanocrystalline diamond grains with sizes range from 2. to 80 nm and contain a large amount of grain *** surface roughness of the films is measured as Ra<*** Raman spectroscopy,XRD pattern,and FE-TEM image of the films indicate the presence of nanocrystalline diamond.A new process is used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure,including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond *** composite diamond coatings not only display good adhesion and wear resistant properties,but also have smooth surfaces that are liable to *** coating technology can not only meet the requirement of the adhesion of diamond coatings,but also reduce surface roughness of diamond coatings effectively,thus remove the obstacles for the industrialization of CVD diamond *** diamondcoated dies with these composite coatings show obvious effect in the practical application.

关键词： Hot filament CVD Nanocrystalline diamond film Composite coatings Diamond-coated dies

Study on an Explosion Treated Steel Weld Metal with Prepared Crack

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Journal of Materials science & Technology 2001年第3期17卷 385-387页

作者： Xiaonan GUO and Xin LONG school of Materials science and {2., {3. jiao tong University, shanghai 2.0030, china Huaining CHEN and Liangshan CHEN Institute of Metal Research, Chinese Academy of sciences, Shenyang 110016, china Guangjun GAI Depa Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

A softening zone with recrystallized grain around the prepared crack tip in the shock waves treated C-Mn steel weld metal was observed. It is suggested that a dynamic recovery occurred around the prepared crack tip even at a low explosion pressure (5 GPa) because of the stress and strain concentration at the crack tip when shock waves pass through. This result supports the previous work on the improved mechanical properties of a shock treated welded joint with residual crack from the viewpoint of microstructure.

关键词： Study on an Explosion Treated Steel Weld Metal with Prepared Crack very high Chen

Laser Powder Deposition of a Fe-Ni-Cr Superalloy:Analysis of Microstructure Formation and Mechanical Properties

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稀有金属材料与工程 2011年第S4期40卷 283-287页

作者： Huang Jian,Nie Pulin,Zhang Yaocheng,Liu Honggang,Li Zhuguo,Wu Yixiong shanghai Key Laboratory of Materials Laser Processing and Modification,school of Materials {2. and {3.,shanghai jiao tong University,shanghai 2.02.0,china shanghai jiao {2. Univ Shanghai Key Lab Mat Laser Proc & Modificat Sch Mat Sci & Engn Shanghai 200240 Peoples R China

Laser powder deposition (LPD) is a very promising repair technique for gas turbine components,which injects the melted powder into the surface of the part and forms the clad with designed *** this paper Fe-Ni-Cr powder is deposited by LPD,and heat treatment is subsequently employed for optimizing the microstructure and improving the mechanical properties of the as-deposited *** microstructure of the as-deposited clad consists of Nb bearing Laves phase and γ austenite *** phase γ'' can be precipitated by post heat treatment for increasing the mechanical *** the existence of Laves phase weakens the mechanical properties of the clad,even inducing the hot ***,DTA results show liquation reaction of Laves phase is as high as 1141 ℃.The solution treatment under 980 ℃ hardly dissolves the Laves *** is needed to control the precipitation of Laves phase by further work.

关键词： Fe-Ni-Cr superalloy laser powder deposition (LPD) strengthening phase Laves phase

Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

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science china Chemistry 2010年第12期53卷 2497-2508页

作者： PANG Yan 1,LIU JinYao 1,SU Yue 1,ZHU BangShang 2.HUANG Wei 1,ZHOU YongFeng 1,ZHU XinYuan 1,2.& YAN DeYue 1 1 school of Chemistry and Chemical engineering,State Key Laboratory of Metal Matrix Composites,{2. {3. tong University,{2. 2.02.0,china 2.Instrumental Analysis Center,{2. {3. tong University,{2. 2.02.0,china school of Chemistry and Chemical engineering State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai China Instrumental Analysis Center Shanghai Jiao Tong University Shanghai China

A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by *** obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 ***,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide *** a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular *** vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug *** cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living *** tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free *** of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

关键词： hyperbranched polymer unimolecular micelle drug delivery

Multi-channel radar array design method and algorithm

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science china(Information sciences) 2010年第7期53卷 1470-1480页

作者： SU Yi1*, ZHU YuTao1, YU WenXian2. XU HongBo1 & LEI WenTai1 1school of Electronic science and {2., National University of Defense Technology, Changsha 410073.{3. 2.0} of Electric, Information and Electrical {2., shanghai jiao tong University, shanghai 2.02.0,{3. school of Electronic science and {2. National University of Defense Technology Changsha China school of Electric Information and Electrical Engineering Shanghai Jiao Tong University Shanghai China

The array design of radar antenna is no more a new problem at all. Nevertheless, the array design of multi-channel radar, especially that of MIMO (multiple-input multiple-output) radar, is a new problem. The performance of space diversion and spatial sampling of target scattering are dependent on the array design of MIMO radar, and consequently, which in turn will determine the performances of target parameter estimation, DOA, and imaging. In this paper, commencing with target scattering model, T/R signal model of MIMO radar, and spatial sampling ability for this system are analyzed. Conceptually, under the far field condition, spatial convolution principle determines the array design theory. Based on this idea, array design method and also algorithm are proposed in this paper.

关键词： MIMO-radar antenna arrays DOA estimation spatial sampling imaging algorithm