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Corrosion and electrochemical behavior of as-cast Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys in 5%NaCl aqueous solution

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Progress in Natural Science:Materials International 2011年第4期21卷 314-321页

作者： Xin ZHANG~(1,2,3),Kui ZHANG~1,Xing-gang LI~1,Cong WANG~4,Hong-wei LI~(2,3),Chang-shun WANG~(2,3),Xia DENG~1 1.State Key Laboratory for Fabrication and Processing of Nonferrous Metals, beijing General research institute for Nonferrous Metals,beijing 100088,china 2.beijing Engineering research Center for Advanced Manufacturing and Evaluation of special Vehicle Parts,beijing 100072,china 3.institute of technology,beijing North Vehicle Group Corporation,beijing 100072,china 4.Fengtai Military Representative Office,beijing Military Representative Office,PLA,beijing 100072,china [a] State Key Laboratory for Fabrication and Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous Metals Beijing 100088 China [b] beijing Engineering research Center for Advanced Manufacturing and Evaluation of special Vehicle Parts Beijing 100072 China [c] institute of technology Beijing North Vehicle Group Corporation Beijing 100072 China [d] Fengtai Military Representative Office Beijing Military Representative Office PLA Beijing 100072 China

The corrosion mechanism of the as-cast Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloy immersed in 5%NaCl aqueous solution was investigated by electrochemical test and *** electrochemical results indicate that the corrosion resistance of Mg-5Y-7Gd-1Nd-0.5Zr alloy in 5%NaCl aqueous solution gradually deteriorates with immersion time increasing from 2 h,24 h,60 h,to 108 h,which is consistent with the SEM observation of corrosion *** Cl-anion leads to the initiation and development of the corrosion pits,and Mg-5Y-7Gd-1Nd-0.5Zr alloy exhibits filiform type of attack under significant anodic control of magnesium solution *** corrosion potential becomes noble with increasing immersion time.

关键词： magnesium alloys Mg-5Y-7Gd-1Nd-0.5Zr corrosion electrochemical behavior

Liquid propellant analogy technique in dynamic modeling of launch vehicle

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Science china(Technological Sciences) 2010年第8期53卷 2102-2110页

作者： PAN ZhongWen 1,2 ,XING YuFeng 1 ,ZHU LiWen 2 ,DONG Kai 2 &SUN Mu 2 1Solid Mechanics research Center,beijing University of Aeronautics and Astronautics,beijing 100191,china 2 beijing Astronautics Systems Engineering institute,beijing 100076,china 1. Solid Mechanics research Center Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Beijing Astronautics Systems Engineering Institute Beijing 100076 China

The coupling effects among lateral mode,longitudinal mode and torsional mode of a launch vehicle cannot be taken into account in traditional dynamic analysis using lateral beam model and longitudinal spring-mass model *** deal with the problem,propellant analogy methods based on beam model are proposed and coupled mass-matrix of liquid propellant is constructed through additional mass in the present *** an integrated model of launch vehicle for free vibration analysis is established,by which research on the interactions between longitudinal and lateral modes,longitudinal and torsional modes of the launch vehicle can be *** examples for tandem tanks validate the present method and its necessity.

关键词： dynamic characteristics coupled mass integrative modeling propellant analogy

Progress and review of the studies on the end-Triassic mass extinction event

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Science china Earth Sciences 2005年第12期48卷 2049-2060页

作者： DENG Shenghui1,2, LU Yuanzheng1,2,3 & XU Daoyi4 1. research institute of Petroleum Exploration and Development, beijing 100083, china 2. Key Laboratory of Oil and Gas Reservoir of Petrochina, beijing 100083, china 3. china University of Geosciences, beijing 100083, china 4. institute of Geology, china Earthquake Administration, beijing 100029, china 1. research institute of Petroleum Exploration and Development 100083 Beijing China 2. Key Laboratory of Oil and Gas Reservoir of Petrochina 100083 Beijing China 3. china University of Geosciences 100083 Beijing China 4. institute of Geology China Earthquake Administration 100029 Beijing China

The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. china has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

关键词： progress, review, end-Triassic, mass extinction, mechanism, Tr-J boundary.

High Throughput SNP Genotyping with Two Mini-sequencing Assays

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Acta Biochimica et Biophysica Sinica 2004年第6期36卷 379-384页

作者： Chunqing LUO1,2#, Libin DENG1#, and Changqing ZENG1,2* The institute of Genetic and Developmental Biology, the Chinese Academy of Sciences, beijing 100101, china 2beijing Genomics institute, the Chinese Academy of Sciences, beijing 101300, china The institute of Genetic and Developmental Biology the Chinese Academy of SciencesBeijing 100101 China beijing Genomics institute the Chinese Academy of SciencesBeijing 101300 China

Two mini-sequencing methods, FP-TDI (template-directed dye-terminator incorporation with fluorescence-polarization) and MassArray (matrix assisted laser desorption ionization time of flight detection mass spectrometry), were optimized. A numeric standard was introduced to evaluate the SNP scoring quality of FP-TDI assay, thus made the optimization work easier. At the same time, using multi-PCR technology, 8-plex genotyping of MassArray assay was successfully carried out, some softwares were developed and the data process of MassArray was highly automated. Then these two methods were applied to high throughput SNP genotyping, the accuracy, efficiency and robustness were compared. The result shows FP-TDI is more sensitive to the concentration of SNPprimer and PCR product, as well as extension cycles, the SNPprimer length of FP-TDI should be 24–30 bp long, whereas MassArray assay prefers to be as short as only 16 *** 6440 SNP sites of human chromosome 3 were genotyped in a sample of 90 individuals, 4792 sites by FP-TDI assay and 1648 sites by MassArray assay, the success rates of FP-TDI and MassArray were 67.7% and 93.6% respectively. The throughput of MassArray was higher than FP-TDI, and the cost of MassArray was lower, MassArray was more suitable for high throughput SNP genotyping.

关键词： SNP genotyping FP-TDI MassArray high throughput

Giant complete automaton for uncertain multiple string matching and its high speed construction algorithm

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Science china(Information Sciences) 2011年第8期54卷 1562-1571页

作者： HU Yue 1,2, GAO QingShi 1,2 ,GUO Li 2 & WANG PeiFeng 1 1 School of Information Engineering,University of Science and technology beijing,beijing 100083,china 2 institute of Computing technology,Chinese Academy of Sciences,beijing 100190,china 1. School of Information Engineering University of Science and Technology Beijing Beijing 100083 China2. Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China

Multiple string matching is often completed under the presence of U- or V-uncertain-strings,or combinations *** large numbers of strings with U-, V-,and U-V-uncertain-strings,including the interleaving of two or more uncertain strings,is important to thoroughly gathering useful information and detecting harmful *** paper proposes a complete automaton and its high-speed construction algorithm for large-scale U-, V-,and U-V-uncertain multiple strings,including two or more uncertain strings interlaced with one *** maximum number of parallel complete automation of the V-uncertain string is also *** paper reveals that there are two kinds of pretermissions,i.e.,similarly-connected and interlaced-string pretermissions,and that mistake may appear in the matching of the regular expressions,or states in the automaton may increase in number,if the intersection of the U-uncertain strings sets and the homologous subsequent special point in the U-uncertain strings sets are not eliminated from the whole system.

关键词： multiple string matching U-uncertain-strings V-uncertain-strings U-V-uncertain-strings complete automaton

The Influence of Laser Shock Processing to TC4 Titanium Alloy TIG Welding Bead Microstructure and Properties

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稀有金属材料与工程 2011年第S4期40卷 206-210页

作者： Xu Haiying,Che Zhegang,Zou Shikun,Cao Ziwen Science and technology on Power Beam Processes Laboratory,beijing Aeronautical Manufacturing technology research institute,beijing 100024,china beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China

TC4 titanium tungsten inert gas arc (TIG) weld beads were treated by laser shock processing (LSP) *** a single and multiple times LSP introduced,surface hardness,tensile mechanical properties and fatigue life of those weld joints were *** results showed that:compared with TC4 titanium alloy TIG joints without LSP treatment,those weld beads surface hardness on weld zone and heat affected zone are nearly *** fatigue life of those TC4 TIG weld joints treated by a single time LSP process is *** the LSP times increased,TC4 titanium alloy weld beads tensile strength and yield strength are not obviously *** special elongation of these welding joints treated by different times LSP treatment will be influenced *** elongation of those joints is decreased with the LSP treatment times increased from one to *** welding joint special elongation was reduced to the least degree since three times LSP treatment had been introduced.

关键词： laser shock processing titanium alloy HV hardness tensile properties fatigue life

Ultrasonic Frequency Fast-Convert Pulse Plasma Spraying Power Supply Topology

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稀有金属材料与工程 2011年第S4期40卷 297-301页

作者： Zhang Wei1,Qi Bojin1,Xu Haiying21School of Mechanical Engineering and Automation,BeiHang University,beijing 100191,china2beijing Aeronautical Manufacturing technology research institute,beijing 100024,china BeiHang Univ Sch Mech Engn & Automat Beijing 1000191 Peoples R China beijing Aeronaut Mfg Technol Res Inst Beijing 100024 Peoples R China

Considering the high DC current and high pulse frequency characteristic of ultrasonic frequency fast-convert pulse plasma spraying process,a special power supply topology was proposed,which was composed of the mutual independent base current circuit and peak current *** current circuit was consisted of four parallel direct current power supplies,which was not only to meet the requirements of high power output,but also improved the reliability of power *** on the Boost circuit topology,a peak current circuit was designed,which could reduce effectively the output inductance influence and output ultrasonic frequency pulse high current with fast-convert rising and falling *** on the above techniques,the Ultrasonic frequency fast-convert pulse plasma spraying power supply was *** can output 5-1000A base current,0-250A peak current,and the pulse current frequency band is 20-100kHz,10%～80% duty ratio and pulse current change rate over 50A/μs.

关键词： Ultrasonic frequency pulse Fast-convert Plasma spraying

A preliminary study on seismic design criteria of offshore platforms in Bohai Sea of china

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 223-231页

作者： Peng Yanju1,Lu Yuejun1,Yan Jiaquan2,Tang Rongyu1,Wang Junqin3 and Li Jiagang3 1. institute of Crustal Dynamics,china Earthquake Administration,beijing 100085,china 2. institute of Geophysics,china Earthquake Administration,beijing 100081,china 3. beijing research Center of china National Offshore Oil Corp.,beijing 100027,china institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

This paper analyzes the seismicity in Bohai Sea,introducing a shape factor K to characterize the seismic risk distribution in sub-regions of the sea. Based on the seismic design ground motions for 46 platforms located in the Bohai Sea,a statistical analysis was performed for different peak ground acceleration (PGA) ratios at two different probability levels. In accordance with the two-stage design method,a scheme of two seismic design levels is proposed,and two seismic design objectives are established respectively for the strength level earthquake and the ductility level earthquake. By analogy with and comparison to the Chinese seismic design code for buildings,it is proposed that the probability level for the strength level earthquake and ductility level earthquake have a return period of 200 and 1000 - 2500 years,respectively. The validity of these proposed values is discussed. Finally,the PGAs corresponding to these two probability levels are calculated for different sub-regions of the Bohai Sea.

关键词： fixed offshore platform seismic design level seismic design objective return period Bohai Sea

Physical modeling and spectrum spread analysis of surface clutter in forward scattering radar

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Science china(Information Sciences) 2010年第11期53卷 2310-2322页

作者： LONG Teng, HU Cheng, ZENG Tao & LI XiaoLiang Radar research Laboratory, Department of Electronic Engineering, beijing institute of technology, beijing 100081, china 1. Radar research Laboratory Department of Electronic Engineering Beijing Institute of Technology Beijing 100081 China

In this paper, based on the processing results of measured clutter data in forward scattering radar, a special phenomenon that the clutter spectrum spread is insensitive to the wind speed and carrier frequency is observed. The pendulum model is first time introduced into the physical modeling and formation mechanism analysis of surface clutter, and the quantitative expression of clutter spectrum spread is analytically obtained. Under the assumption of pendulum model, the processing results of measured clutter data agree well with the results of theoretical analysis, which fully verifies the correctness of pendulum model and reveals the formation mechanism of surface clutter spectrum in forward scattering radar. Furthermore, according to the stability of clutter spectrum spread with respect to carrier frequencies and wind speed, the optimal cutofrequencies of clutter filter can be obtained, which establishes the basis for moving target detection and accurate parameters estimation.

关键词： forward scattering radar clutter spectrum pendulum model formation mechanism