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Multi-resolution representation of digital terrain models with terrain features preservation

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Science China(Technological Sciences) 2008年第S1期51卷 145-154页

作者： LI QingQuan1.WANG Zhi1.2.& YANG BiSheng1.1.{1. key {2. of Information engineering in Surveying,Mapping and Remote Sensing,wuhan University,wuhan 430079,China 2.School of Remote Sensing and Information engineering,wuhan University,wuhan 430079,China 1. state {1. {2. of Information engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China2. School of Remote Sensing and Information Engineering Wuhan University Wuhan 430079 China

multi-resolution TIN model is an important issue in the contexts of visu-alization,virtual reality (VR),and geographic information systems (GIS). This paper proposes a new method for constructing multi-resolution TIN models with multi-scale topographic features preservation. The proposed method is driven by a half-edge collapse operation in a greedy framework and employs a new quadric error metric to efficiently measure geometric errors. We define topographic features in a multi-scale manner using a center-surround operator on Gaussian-weighted mean curvatures. Experimental results demonstrate that the proposed method performs better than previous methods in terms of topographic features preservation,and is able to achieve multi-resolution TIN models with a higher accuracy.

关键词： digital terrain models level of detail differential-geometry quadric error metrics topographic feature

HCWCI/Carbon Steel Bimetal Liner by Liquid-Liquid Compound Lost Foam Casting

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Journal of Iron and Steel Research International 2012年第10期19卷 13-19页

作者： XIAO Xiao-feng1.2. YE Sheng-ping2. YIN Wei-xin3, XUE Qiong4 (1. School of Mechanical engineering and Automation, {1. Textile University, {1. 430073, hubei, China 2. state key laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, {1. 430074, hubei, China 3. {1. Zhike Abrasive-Resistant Material Science and Technology Development Co Ltd, {1. 430073, hubei, China 4. College of Science, {1. University of Technology, {1. 430079, hubei, China) [a] School of Mechanical engineering and Automation Wuhan Textile University Wuhan 430073 Hubei China [b] state {1. {2. of Material Processing and Die and Mould Technology Huazhong University of Science and Technology Wuhan 430074 Hubei China [c] wuhan Zhike Abrasive-Resistant Material Science and Technology Development Co Ltd Wuhan 430073 Hubei China [d] College of Science Wuhan University of Technology Wuhan 430079 Hubei China

Impact, friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage. Liner, made from Hadfield steel or alloyed steel, could not have served in wet grinding environment for more than ten months. Composite liner, made from HCWCI (high Cr white cast iron) and carbon steel, has been developed successfully with liquid-liquid composing process based on LFC (lost foam casting). The microstructure of composite was analyzed with optical microscope, SEM (scanning electron microscope)/EDX energy-dispersive X-ray and XRD (X-ray diffraction). According to micrograph, the combination region of two metals was staggered like dogtooth, no mixtures occurred between two liquid metals, and its interface presented excellent metallurgical bonding state. The results of mechanical property test show that, the hardness of HRC, the fracture toughness, and the bending strength are more than 61. 1..5 J/cm{1.and 1.600 MPa, respectively. Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill. The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.

关键词： composite liner bimetal liquid-liquid compound composite interface lost foam casting high Cr white cast iron

Singularity of Some software Reliability Models and Parameter Estimation Method

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wuhan University Journal of Natural Sciences 2000年第1期5卷 35-40页

作者： XU Ren-zuo ZHOU Rui YANG Xiao-qing (state {1. {2. of software engineering, wuhan University, wuhan 43.072. China) wuhan University State Key Laboratory of Software Engineering Wuhan China (GRID:grid.49470.3e) (ISNI:***)

According to the principle, “The failure data is the basis of software reliability analysis”, we built a software reliability expert system (SRES) by adopting the artificial intelligence technology. By reasoning out the conclusion from the fitting results of failure data of a software project, the SRES can recommend users “the most suitable model” as a software reliability measurement model. We believe that the SRES can overcome the inconsistency in applications of software reliability models well. We report investigation results of singularity and parameter estimation methods of experimental models in SRES.

关键词： software reliability measurement models software reliability expert system singularity parameter estimation method path following method maximum likelihood ML-fitting algorithm

A Feedback-Based Web Search Engine

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wuhan University Journal of Natural Sciences 2004年第5期9卷 561-568页

作者： ZHANG Wei-feng 1,2.3 , XU Bao-wen 2.3,4 , ZHOU Xiao-yu 2.3,4 1. Department of Computer Science and engineering, Nanjing University of Posts and Telecommunications, Nanjing 2.0003, Jiangsu, China 2. Department of Computer Science and engineering, Southeast University, Nanjing 2.0096, Jiangsu, China 3. Jiangsu Institute of {2. Quality, Nanjing 2.0096 Jiangsu, China 4. The state key laboratory of {2. engineering, wuhan University, wuhan 43.072. hubei, China Department of Computer Science and engineering Nanjing University of Posts and Telecommunications . Nanjing 210003 Jiangsu China

Web search engines are very useful information service tools in the Internet. The current web search engines produce search results relating to the search terms and the actual information collected by them. Since the selections of the search results cannot affect the future ones, they may not cover most people’s interests. In this paper, feedback information produced by the user’s accessing lists will be represented by the rough set and can reconstruct the query string and influence the search results. And thus the search engines can provide self-adaptability. key words WWW - search engine - query reconstruction - feedback CLC number TP 31.. 1.5.4 Foundation item: Supported by the National Natural Science Fundation of China (60373066). National Grand Fundamental Research 973 Program of China ({1.0{1.B31.1.0). Opening Foundation of state key {1. of software engineering in wuhan University, Opening Foundation of Jiangsu key {1. of Computer Information Processing Technology in Soochow UniversityBiography: ZHANG Wei-feng (1.75-), male, Ph.D. research direction: artificial intelligence, search engine, data mining, network language.

关键词： WWW search engine query reconstruction feedback

Analysis on ignition and extinction of n-heptane in homogeneous systems

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Science China(Technological Sciences) 2005年第5期48卷 556-569页

作者： LIU Yongfeng1.& PEI Pucheng2.1. Mechanical and Electrical {1. Department, Beijing Institute of Civil {1. and Architec-ture, Beijing 1.0044, China 2. {2. key laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 1.0084, China 1. Mechanical and Electrical engineering Department Beijing Institute of Civil Engineering and Architecture 100044 Beijing China 2. {1. key {2. of Automotive Safety and Energy Tsinghua University 100084 Beijing China

To calculate ignition delay times, the governing equations about species and temperature, which are in a closed volume based on the theory of thermal explosion and in a continuously stirred flow reactor, are deducted. The method referred to steady state assumptions is based on the observation that due to very fast chemical processes in combustion problems many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. The steady state solution of the reactor equations describes the three ignition temperature regimes and get “S-shaped curve”. The reduced simplified 4-step mechanism for n-heptane from 1.1. elementary reactions leads with the steady state assumptions to linear differential equations, which is solved. The simulation results of the 4-step reduced mechanism for n-heptane are fitted well with the experiment data. At last, two important parameters are discussed thoroughly and the temperature perturbation is given. It reduces the computational efforts considerably without losing too much accuracy and further supplies numerical methods for turbulent combustion in the diesel engine.

关键词： ignition delay times, thermal runaway, steady state assumptions, continuously stirred flow reactor.

Gradient Gene Algorithm: a Fast Optimization Method to MST Problem

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wuhan University Journal of Natural Sciences 2001年第Z1期6卷 535-540页

作者： Zhang Jin bo, Xu Jing wen, Li Yuan xiang state {1. {2. of software engineering, wuhan University, wuhan 43.072. China state {1. {2. of software engineering Wuhan University Wuhan China

The extension of Minimum Spanning Tree(MST) problem is an NP hard problem which does not exit a polynomial time algorithm. In this paper, a fast optimization method on MST problem——the Gradient Gene Algorithm is introduced. Compared with other evolutionary algorithms on MST problem, it is more advanced: firstly, very simple and easy to realize; then, efficient and accurate; finally general on other combination optimization problems.

关键词： combination optimization minimum spanning tree problem extension of minimum spanning tree problem gradient gene algorithm

Effect of Tin on the Reaction Synthesis of Ternary Carbide Ti_3AlC_2

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Journal of wuhan University of Technology(Materials Science) 2009年第2期24卷 283-286页

作者：周卫兵 School of Materials Science and engineering Wuhan University of Technology

The effect of tin on synthesis of Ti3AlC2.by spark plasma sintering （SPS） from TiC/Ti/Al powders was investigated. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were used for phase identification and microstructure evaluation. The experimental results show that addition of tin can considerably accelerate the synthesis reaction of Ti3AlC2.and fully dense, essentially single-phase polycrystalline Ti3AlC2.could be successfully obtained by sintering 2.iC/1.i/1.l/0.2.n powders at 1.0}0-1.0}0 ℃ under a pressure of 30 MPa. SEM images show that Ti3AlC2.samples in about 2.5 μm thick and 1.-2.μm long platelets can be obtained. The fracture toughness and flexural strength of Ti3AlC2.were 6.5±0.2.MPa·m^1.2.and 560±1. MPa, respectively.

关键词： titanium aluminum carbide spark sintering technique synthesis

Code Component Reuse Supporting Environment (CCRSE) and Its Design Strategy

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wuhan University Journal of Natural Sciences 2003年第2A期8卷 363-367页

作者： Ying Shi, Xu Gang,Yuan Sheng-qiong, Chen Haostate {1. {2. of software engineering, wuhan University, wuhan 43.072. hubei, China wuhan University

Code Component Reuse Supporting Environment (CCRSE), which has been developed by us, is an integrated development environment. CCRSE can provide comprehensive supports for the whole process of reusing code component in the manner of dynamic composition. The architecture and functionality of CCRSE are introduced. The key achievement is giving the three strategies that are vital to successfully design CCRSE. The three strategies include: (1. according to the three pivotal technologies (encapsulation, composition and management) for supporting composition reuse of code component, design three tools respectively. ({1. keep tool for supporting code component development independent of tool for supporting code component composition. (3) strictly restrict code component specification, provide the strong plug and play support for code component composition reuse, and furthest provide transparence to strictly restricted specification of code component in development of component itself.

关键词： Codes (symbols) Design Management

Nb/Ta variations of mafic volcanics on the Archean- Proterozoic boundary: Implications for the Nb/Ta imbalance

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Science China Earth Sciences 2005年第8期48卷 1106-1119页

作者： LIU Yongsheng1.2. GAO Shan1.2. WANG Xuance1. HU Shenghong1.& WANG Jianqi2.1. state key {2. of Geological Processes and Mineral Resources, China University of Geosciences, wuhan 430074, China 2. key {2. of Continental Dynamics, Department of Geology, Northwest University, Xi’an 71.069, China 1. state {1. {2. of Geological Processes and Mineral Resources China University of Geosciences 430074 Wuhan China 2. {1. laboratory of Continental Dynamics Department of Geology Northwest University 710069 Xi’an China

The HFSE and REE of the Precambrian mafic volcanics from the North China craton demonstrate obvious A(Archean)-P(Proterozoic) boundary. The Neoarchean mafic vol- canics show weak correlation between HFSE and TiO2. Their superchondritic Nb/Ta ratio (1..8±1.2. could be attributed to partial melting of mantle peridotite in the presence of garnet. Compared with Neoarchean mafic volcanics, the Paleoproterozoic ones have higher HFSE contents and lower Nb/Ta ratio (1..6±2.9). The significantly elevated HFSE and REE contents of Paleoproterozoic mafic volcanics imply metasomatic enrichment of mantle source, in which Ti-rich silicates could be present as suggested by significant positive correlations between TiO2.and HFSE. The global database of Precambrian mafic volcanics shows a similar A-P boundary. 2. Archean mafic volcanic suites yield an average Nb/Ta ratio of 1..8±1.9 higher than or close to the PM value; Proterozoic mafic volcanics from 2. suites yield an average Nb/Ta ratio of 1..7±4.1.close to the bulk continental crust (BCC) value (1.―1..5). Thus, we suggest that the Nb/Ta deficit could be mainly formed in post-Archean time. Archean mafic volcanics could be one of the geochemical reservoirs complementing the low Nb/Ta of the post-Archean continental crust and DM.

关键词： Precambrian mafic volcanics, Nb/Ta deficit, Archean-Proterozoic boundary.