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Microstructure failure in ferrite-martensite dual phase steel under in-situ tensile test

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Journal of Iron and Steel Research International 2017年第3期24卷 350-356页

作者： Rui-bin Gou Wen-jiao Dan Wei-gang Zhang min Yu chun-yu Zhang Yin-hu Qiao Lu Ma Department of Engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China School of Mechanical Engineering Anhui Science and Technology University Bengbu 233100 Anhui China Innovation Center for Advanced Ship and Deep Sea Exploration Shanghai Jiao Tong University Shanghai 200240 China College of Architecture Anhui Science and Technology University Bengbu 233100 Anhui China

To investigate microstructure failure in ferrite-martensite dual phase steel,in-situ observations were performed on multiple plate DP800 specimens during uniaxial tensile tests. Microstructure evolution of the observed region was investigated in details. The experimental data showed that micro-cracks in various regions differed in the initiation time,and micro-failures mainly occurred from the locations with typical characteristics of stress concentration（ i. e. ferrite interiors,the interfaces of ferrite-martensite grains and the martensite-martensite interfaces）. Growth of micro-crack generally experienced the following stages： cracking from martensite boundaries,tiny particles in ferrite interiors,or martensite interiors,propagating in ferrite,bypassing martensite boundaries,or passing through martensite-martensite interfaces,finally ending on martensite boundaries. Martensite was one important source of micro-failure and changed the propagation of micro-cracks significantly. Microstructure deformation was inhomogeneous in the stage of plastic deformation.

关键词： Micro-fracture Dual phase steel Ferrite Martensite In-situ observation

Periodic oscillation and fine structure of wedge-induced oblique detonation waves

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Acta Mechanica Sinica 2011年第6期27卷 922-928页

作者： ming-Yue Gui Bao-chun Fan gang Dong State Key Laboratory of Transient Physics Nanjing University of Science and Technology 210094 Nanjing China State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology 100081 Beijing China

An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30 turning angle is simulated numerically using Euler equation and one-step rection *** fifth-order WENO scheme is adopted to capture the shock *** numerical results show that with the compression of the wedge wall the detonation wave front structure is divided into three sections：the ZND model-like strcuture,single-sided triple point structure and dual-headed triple point *** first structure is the smooth straight,and the second has the characteristic of the triple points propagating dowanstream only with the same velocity,while the dual-headed triple point structure is very *** detonation waves facing upstream and downstream propagate with different velocities,in which the periodic collisions of the triple points cause the oscillation of the detonation wave *** oscillation process has temporal and spatial *** addition,the triple point trace are recorded to obtain different cell structures in three sections.

关键词： Oblique detonation wave Wedge - Periodic oscillation Fine structure

Effects of Mg/PTFE pyrotechnic compositions on reignition characteristics of base bleed propellants and heating mechanism

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Defence Technology（防务技术） 2022年第1期18卷 94-108页

作者： Xiao-chun Xue Long-ze Ma Yong-gang Yu Schooi of Enerey and Power Engineering Nanjing Universiry of Science and Techmology Narine lianesu 210094 China BYD Compary Liruied ShenzheL Guanedong 518118 Chna

The effects of magnesium/polytetrafluoroethylene(Mg/PTFE)pyrotechnic compositions on the coupled flow field and reignition mechanism are important aspects governing the perfommance and range of base bleed projectiles(BBPs).Owing to a decrease in pressure and temperature when the BBP leaves the muzzle,rapid depressurization occurs,which extinguishes the base bleed *** Mg/PTFE py-rotechnic composition pressed in the igniter of the base bleed unit(BBU)provides additional energy to the BBU via a chemical ***,the extinguished base bleed propellant is reignited under the effect of high-temperature combustion gas jets from the *** this study,a numerical analysis is conducted to evaluate the effects of PTFE and Mg granularity as well as Mg/PTFE pyrotechnic *** to the rapid depressurization,the temperature and pressure was found to decrease fordifferent Mg/PIFE pyrotechnic ***,the depressurization time increased as the PTFE granularity increased,the Mg granularity decreased,and the Mg content *** the pressure in the combustion chamber of the BBU decreased to the atmospheric pressure,the combustion gas jets from the igniter expand upstream(rather than downstream).However,these combustion gas jets exhibit different axial and radial expansion characteristics depending on the pyrotechnic compositions used,The results show that the reignition delay time,ta,of the base bleed propellant was 377.608,94.27,387.243,523.966,and 221.094 ms for cases A-E,***,it was concluded that the Mg/PTFE pyrotechnic composition of case B was the most beneficial for the reignition of the base bleed propellant,with the earliest addition of energy and mass to the BBP.

关键词： Thermal effect High-temperature combustion gas Mg/PTFE pyrotechnic Compositions Reignition

Imazamox microbial degradation by common clinical bacteria: Acinetobacter baumannii IB5 isolated from black soil in China shows high potency

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Journal of Integrative Agriculture 2016年第8期15卷 1798-1807页

作者： LIU chun-guang YANG Xin LAI Yang LU Hong-gang ZENG Wei-min GENG Gui YANG Feng-shan Key Laboratory of Microbiology Life Science College Heilongjiang University Engineering Research Center of Agricultural Microbiology Technology Ministry of Education Sugar Beet Research Institute Chinese Academy of Agricultural Sciences Crop Research Institute Heilongjiang University

supported by the Public Welfare Industry Research Project, ministry of Agriculture of China （201203098）;the Harbin Applied Technology Research and Development Project, China （Youth Reserve Talents Class A： 2015RAQ... 详细信息

关键词： imazamox biodegradation Acinetobacter baumannii metabolites herbicide

Applying Multiquadric Quasi-Interpolation to Solve KdV Equation

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Journal of Mathematical Research and Exposition 2011年第2期31卷 191-201页

作者： min Lu XIAO Ren Hong WANG chun gang ZHU School of Mathematical Sciences Dalian University of Technology Liaoning 116024 P. R. China

Quasi-interpolation is very useful in the study of approximation theory and its applications,since it can yield solutions directly without the need to solve any linear system of *** on the good performance,Chen and Wu presented a kind of multiquadric （MQ） quasi-interpolation,which is generalized from the L D operator,and used it to solve hyperbolic conservation laws and Burgers’ *** this paper,a numerical scheme is presented based on Chen and Wu’s method for solving the Korteweg-de Vries （KdV） *** presented scheme is obtained by using the second-order central divided difference of the spatial derivative to approximate the third-order spatial derivative,and the forward divided difference to approximate the temporal derivative,where the spatial derivative is approximated by the derivative of the generalized L D quasi-interpolation *** algorithm is very simple and easy to implement and the numerical experiments show that it is feasible and valid.

关键词： KdV equation multiquadric(MQ) quasi-interpolation numerical solution

Nother-type theorem of piecewise algebraic curves on triangulation

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Science China Mathematics 2007年第9期50卷 1227-1232页

作者： chun-gang ZHU Ren-hong WANG Institute of Mathematical Sciences Dalian University of TechnologyDalian 116024China

The piecewise algebraic curve is a kind generalization of the classical algebraic curve. Nther-type theorem of piecewise algebraic curves on the cross-cut partition is very important to construct the Lagrange interpolation sets for a bivariate spline *** this paper,using the properties of bivariate splines,the Nther-type theorem of piecewise algebraic curves on the arbitrary triangulation is presented.

关键词： piecewise algebraic curves bivariate splines Nother-type theorem triangulation

Theoretical Investigations of the Catalytic Role of Water in Propene Epoxidation on Gold Nanoclusters： A Hydroperoxyl- Mediated Pathway

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Nano Research 2011年第1期4卷 131-142页

作者： chun-Ran Chang Yang-gang Wang Jun Li Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of ministry of Education TsinghuaUniversity Beijing 100084 China

We report a comprehensive theoretical investigation of the catalytic reaction mechanisms of propene epoxidation on gold nanoclusters using density functional theory （DFT）. We have shown that water acts as a catalytic promoter for propene epoxidation on gold catalysts. Even without reducible supports, hydroperoxyl （OOH） and hydroxyl （OH） radicals are readily formed on small-size gold clusters from co-adsorbed H20 and 02, with energy barriers as low as 4-6 kcal/mol （1 cal = 4.186 J）. Propene epoxidation occurs easily through reactions between C3H6 and the weakened O-O bond of the OOH radicals on the surfaces of gold clusters.

关键词： Gold nanocluster propene epoxidation hydroperoxyl radical density functional theory

Degenerations of rational Bézier surface with weights in the form of exponential function

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Applied Mathematics(A Journal of Chinese Universities) 2017年第2期32卷 164-182页

作者： ZHANG Yue ZHU chun-gang GUO Qing-jie School of Mathematical Sciences Dalian University of TechnologyDalian 116024China School of Mathematics and Physics Science Dalian University of TechnologyPanjin 124221China.

Rational Bezier surface is a widely used surface fitting tool in CAD. When all the weights of a rational B@zier surface go to infinity in the form of power function, the limit of surface is the regular control surface induced by some lifting function, which is called toric degenerations of rational Bezier surfaces. In this paper, we study on the degenerations of the rational Bezier surface with weights in the exponential function and indicate the difference of our result and the work of Garcia-Puente et al. Through the transformation of weights in the form of exponential function and power function, the regular control surface of rational Bezier surface with weights in the exponential function is defined, which is just the limit of the surface. Compared with the power function, the exponential function approaches infinity faster, which leads to surface with the weights in the form of exponential function degenerates faster.

关键词： rational Bezier surface weights regular control surface toric degenerations exponential function.

CONJUGATE FLOWS OVER A STEP IN A THREE-LAYER FLUID

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Journal of Hydrodynamics 2002年第4期14卷 15-23页

作者： Wei, gang Le, Ja-chun Dai, Shi-Qiang Inst. of Appl. Math. and Mech. Shanghai Univ. Shanghai 200072 China Sch. of Sci. P.L.A Univ. of Sci. and Eng. Nanjing 211101 China

The conjugate flows over a step with the height h_0, which might be positive or negative, was studied in a three-layer fluid and the coupled nonlinear equations were derived, with which the effects of varying height h_0 on the existence and evolution of conjugate flows were examined. It is concluded that the conjugate flow is sharply sensitive to the thickness of fluid layers and its characteristics alters remarkably due to the existence of the step. As the flow climbs up a step (h_0>0), the conjugate flow with a convex lower interface and a concave upper interface is allowed to appear, while the flow with the concave lower interface or the simultaneous concave interfaces will be depressed. As the flow goes down a step (i.e., h_0<0), on most occasions only one kind of conjugate flow could exist, which prossesses the form with the simultaneous convex interfaces and will disappear rapidly with the increase of the step depth.

关键词： conjugate flow flat solitary wave stratified flow step topography three-layer fluid