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Hierarchical Bayesian Calibration and On-line Updating Method for Influence Coefficient of Automatic Dynamic Balancing machine

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 876-882页

作者： ZHANG Jian wu Jianwei ma Zhiyong Mechanical Design Institute Zhejiang University Hangzhou 310027 China

Measurement error of unbalance＇s vibration response plays a crucial role in calibration and on-line updating of influence coefficient（IC）. Focusing on the two problems that the moment estimator of data used in calibration process cannot fulfill the accuracy requirement under small sample and the disturbance of measurement error cannot be effectively suppressed in updating process, an IC calibration and on-line updating method based on hierarchical Bayesian method for automatic dynamic balancing machine was proposed. During calibration process, for the repeatedly-measured data obtained from experiments with different trial weights, according to the fact that measurement error of each sensor had the same statistical characteristics, the joint posterior distribution model for the true values of the vibration response under all trial weights and measurement error was established. During the updating process, information obtained from calibration was regarded as prior information, which was utilized to update the posterior distribution of IC combined with the real-time reference information to implement online updating. Moreover, Gibbs sampling method of markov Chain Monte Carlo（MCMC） was adopted to obtain the maximum posterior estimation of parameters to be estimated. On the independent developed dynamic balancing testbed, prediction was carried out for multiple groups of data through the proposed method and the traditional method respectively, the result indicated that estimator of influence coefficient obtained through the proposed method had higher accuracy; the proposed updating method more effectively guaranteed the measurement accuracy during the whole producing process, and meantime more reasonably compromised between the sensitivity of IC change and suppression of randomness of vibration response.

关键词： influence coefficient hierarchical Bayesian calibration online updating dynamic balancing markov Chain Monte Carlo(MCMC)

Generator,multiquadric generator,quasi-interpolation and multiquadric quasi-interpolation

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Applied mathematics(A Journal of Chinese Universities) 2011年第4期26卷 390-400页

作者： wu Zong-min ma Li-min Shanghai Key Laboratory for Contemporary Applied mathematics. School of mathematical Sciences Fudan University Shanghai 200433 China.

The aim of this survey paper is to propose a new concept ＂generator＂. In fact, generator is a single function that can generate the basis as well as the whole function space. It is a more fundamental concept than basis. Various properties of generator are also discussed. Moreover, a special generator named multiquadric function is introduced. Based on the multiquadric generator, the multiquadric quasi-interpolation scheme is constructed, and furthermore, the properties of this kind of quasi-interpolation are discussed to show its better capacity and stability in approximating the high order derivatives.

关键词： Generator function representation approximation numerical differentiation multiquadric quasi-interpolation

Penta-coordinated phosphorus structure analysis on kinases

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Science China Chemistry 2004年第5期47卷 420-427页

作者： LI wu ma Yuan ZHAO Yufen Key Lab of Bioorganic Phosphorus Chemistry and Chemical Biology of Ministry of Education Department of Chemistry School of Life Sciences Tsinghua University Beijing 100084 China Key Lab of Bioorganic Phosphorus Chemistry and Chemical Biology of Ministry of Education Department of Chemistry School of Life Sciences Tsinghua University Beijing 100084 China Key Lab of Bioorganic Phosphorus Chemistry and Chemical Biology of Ministry of Education Department of Chemistry School of Life Sciences Tsinghua University Beijing 100084 China

In this paper, based on the known crystal structures of Square Pyramid (SP) and Trigonal Bipyramid (TBP) penta-coordinated phosphorus compounds containing amino acid side chains, such as amino, carboxyl, hydroxyl or thiol, a software designed to survey the P(5)-Structure of phosphorylated proteins. By this software, it was found that 382 of 398 phos- phorus-related kinases (96%) from current PDB could go through the penta-coordinated phos- phorus transition state or intermediate. For example, in protein 1HE8, amino group in Lysine16 was within 3.58 ?from the phosphorus atom, and a potential TBP structure consisting GNP2 and NZ could be overlapped with an authentic TBP with an RMSD value of 0.71 ?.

关键词： penta-coordinated phosphorus structures, kinases.

Tensile properties and fractographs of Ti–2.5Al–1.5Mn foils at different temperatures

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Rare Metals 2017年第4期36卷 247-255页

作者： Zhen-wu ma Guo-Quan Tong Feng Chen College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016China

The tensile properties and fractographs of Ti- 2.5Al-1.5Mn foils at different temperatures were investi- gated. It is observed that material properties closely cor- relate with the thickness （T） to grain size （d） ratio and deformation temperature. Tensile analysis shows that local deformation is the main deformation feature in foils forming at room temperature, which may lead to premature fracture. The causes of inhomogeneous deformation behavior are the limited number of deformable grains contained in deformation zone and the weak transferability of hardening among different grains. Fracture analysis reveals that the size of dimples can represent the ductility of foils at room temperature. With the further increase of deformation temperature, the main plastic deformation mode of foils is transformed from intragranular disloca- tions and twin crystal to grain-boundary gliding and roll- ing. In conclusion, foil forming at elevated temperature can increase the hardening transferability and the number of deformable grains in deformation zone, which is an effective method to improve the formability and reduce the scatter of material properties.

关键词： Size effects Titanium foils Tensile properties Homogeneous deformation Elevated temperature

A Survey of Newtonian Core-Shell Systems with Pseudo High Order Symplectic Integrator and Fast Lyapunov Indicator

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Chinese Journal of Astronomy and Astrophysics 2007年第4期7卷 601-610页

作者： Jun-Fang Zhu Xin wu Da-Zhu ma Department of Physics Nanchang University Nanchang 330031

Newtonian core-shell systems, as limiting cases of relativistic core-shell models under the two conditions of weak field and slow motion, could account for massive circumstellar dust shells and rings around certain types of star remnants. Because this kind of systems have Hamiltonians that can be split into a main part and a small perturbing part, a good choice of the numerical tool is the pseudo 8th order symplectic integrator of Laskar ＆ Robutel, and, to match the symplectic calculations, a good choice of chaos indicator is the fast Lyapunov indicator （FLI） with two nearby trajectories proposed by wu, Huang ＆ Zhang. Numerical results show that the FLI is very powerful when describing not only the transition from regular motion to chaos but also the global structure of the phase space of the system.

关键词： celestial mechanics - chaos - methods: numerical

INFLUENCE OF FILLING WATER ON AIR CONCENTRATION

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Journal of Hydrodynamics 2011年第5期23卷 601-606页

作者： wu Jian-hua ma Fei DAI Hui-chao College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The filling water inside the cavity below an aerator occurs for the flow of low Froude number or the small bottom slope of a spillway. The aerator may cease to protect against cavitation damages, and may even act as a generator of cavitation if it is fully filled by water. The experiments were conducted to investigate the influences of the geometric parameters, and then the filling water on the air concentration. The results show that the filling water, or the net cavity length, is closely related to the plunging jet length for a given aerator, and the air concentration at some section is proportional to the ratio Ln/Lj at a fixed Lj for different geometric parameters of aerators. Secondly, at the same ratio of Ln / Lj, the aerator with a larger height or a larger angle of ramp, or a larger bottom slope, would have a larger plunging jet length, and then a larger net cavity length based on the ratio of Ln / Lj. As a result, the large space of cavity, or the high air concentration of the flow could be obtained although the filling water increases also based on the fact that Lf = Lj - Ln. It is the space of the cavity that is the dominant factor to affect the air concentration of the flow.

关键词： aerator air concentration filling water jet length net cavity length

Fabrication and Testing of Carbon Fiber Reinforced Truss Core Sandwich Panels

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Journal of materials Science & Technology 2009年第4期25卷 547-550页

作者： Bing Wang Linzhi wu Li ma Qiang Wang Shanyi Du Center for Composite materials Harbin Institute of Technology Harbin 150001 China

Truss core sandwich panels reinforced by carbon fibers were assembled with bonded laminate facesheets and carbon fiber reinforced truss cores. The top and bottom facesheets were interconnected with truss cores. Both ends of the truss cores were embedded into four layers of top and bottom facesheets. The mechanical properties of truss core sandwich panels were then investigated under out-of-plane and in-plane compression loadings to reveal the failure mechanisms of sandwich panels. Experimental results indicated that the mechanical behavior of sandwich structure under in-plane loading is dominated by the buckling and debonding of facesheets.

关键词： Sandwich panel Truss core Carbon fiber

Lifetime prediction and failure analysis of organic coatings by EIS

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 455-458页

作者： YAN Rui wu Hang ma Shi-ning XU Bin-shi Surface Engineering Research Institute of CMES Chinese Mechanical Engineering Society Beijing 100072 China Surface Engineering Research Institute of CMES Chinese Mechanical Engineering Society Beijing 100072 China Surface Engineering Research Institute of CMES Chinese Mechanical Engineering Society Beijing 100072 China Surface Engineering Research Institute of CMES Chinese Mechanical Engineering Society Beijing 100072 China

Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the substrate. But unavoidable completely small pores, cracks and other defects in organic coatings may cause ions, water, gases, and other corrosive species penetrate and distribute in the coatings, causing accumulation and swelling of coatings, so leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive medium, consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. So the absorbability of the coatings to water may be one of the most important factors in undercoating corrosion. In recent years, electrochemical impedance spectroscopy (EIS) has been established and frequently used as a non-destructive testing method for assessing the performance of organic coatings, especially for the determination of the water content in organic coatings, since the capacitance of the coatings is sensitive to the penetration of water. So from EIS it can extract a wealth of information on the electrochemical corrosion of coated steels, especially, it can be utilized to assess organic coatings used under particular surroundings. The principle, methods and application of EIS on evaluating life-span and analyzing failure mechanism of organic coatings are also introduced briefly. Combining other analysis techniques such as XRD, SEM and FTIR with electrochemical technique, it will blaze a way in studying degradation mechanism of organic coatings and estimating their lifetime.

关键词： organic coatings lifetime prediction failure analysis electrochemical impedance spectro scopy

The synthesis of polyfluoroalkoxylbenzaldehydes

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Chinese Journal of Chemistry 1991年第1期9卷 84-91页

作者： HUANG Wei-Yuan ma wu-Ping Shanghai Institute of Organic Chemistry Chinese Academy of SciencesShanghai 200032

Several polyfluoroalkoxyl benzaldehydes were synthesized from the nucleophilic reaction between polyfluoroalkanesulfonate and various sodium phenolates with cetyltrimethylammonium bromide or tetrabutylammonium bromide as PTC. The yields were in the range of 55%-70%, Using a modified procedure Cl(CF_2)_2SO_2Cl was prepared from ClCF_2CF_2I with an improved yield of 91% and was used to synthesize the polyfluoroalkanesulfonate 2′.

关键词： CF The synthesis of polyfluoroalkoxylbenzaldehydes CHO