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Arc erosion behavior of a nanocomposite W-Cu electrical contact material

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Rare Metals 2006年第1期25卷 37-42页

作者： CHEN Wenge KANG Zhanying SHEN Hongfang DING Bingjun School of Materials Science and Engineering Xi＇an University of Technology Xi＇an 710048 China Department of Materials Physics Xi＇an Jiaotong University Xi＇an 710049 China

The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by scanning eleclion microscopy. It is concluded that the nanocomposite W-Cu electrical contact material shows a characteristic of spreading arcs. The arc breakdown of a commercially used W-Cu alloy was limited in a few areas, and its average arc erosion rate is twice as large as that of the former. Furthermore, it is also proved that the arc extinction ability and arc stability of the nanocomposite W-Cu material are excellent, and melting is the major failure modality in the make-and-break operation of arcs.

关键词： arc erosion W-Cu alloy contact materials nanocomposite

A complex variable meshless method for fracture problems

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Science China(Physics,Mechanics & Astronomy) 2006年第1期49卷 46-59页

作者： CHENG Yumin1 & LI Jiuhong2 1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai university, Shanghai 200072, China 2. Department of Building Engineering, xi’an university of technology, xi’an 710048, China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China Department of Building Engineering Xi’an University of Technology Xi’an China

Based on the moving least-square (MLS) approximation, the complex variable moving least-square approximation (CVMLS) is discussed in this paper. The complex variable moving least-square approximation cannot form ill-conditioned equations, and has greater precision and computational efficiency. Using the analytical solution near the tip of a crack, the trial functions in the complex variable moving least-square approxi- mation are extended, and the corresponding approximation function is obtained. And from the minimum potential energy principle, a complex variable meshless method for fracture problems is presented, and the formulae of the complex variable meshless method are obtained. The complex variable meshless method in this paper has greater precision and computational efficiency than the conventional meshless method. Some examples are given.

关键词： moving least-square approximation, complex variable moving least-square approximation, meshless method, complex variable meshless method, fracture.

A Case Study:Distribution of Bacterial and Fungal Aerosols in Air-Conditioning Systems in Shaanxi History Museum

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湖南大学学报（自然科学版） 2009年第S1期36卷 10-14页

作者： LI An-gui,HOU Juan-juan,JI Zeng-bao,ZHU xiao-bin(School of Environmental & Municipal Engineering,xi’an university of Architecture and technology,xi’an,Shaanxi 710055,China) School of Environmental and Municipal Engineering Xi'an University of Architecture and Technology Xi'an 710055 China

In order to investigate the bacteria and fungi aerosol characteristic distribution in HVAC-system and its components at Shaanxi History *** were performed to probe the bacteria and fungi aerosol in HVAC systems,located at xi'an city,*** results showed that there was fungi growth inside the ventilation ducts,fungi contamination was worse than bacteria,and both of them were distributed into occupied space with the air supply *** dominating genera of fungi was found to be Penicillium *** Aspergillus spp.,which was respectively 46.1% and 20.7% in settling fungi,and the dominating genera of fungi in dust were Cladosporium *** Penicillium spp.,which was 41.8% and 30.1% *** suggests that available measures to improve and control the performance of HVAC-systems such as the maintenance,management and cleaning should be taken to prevent this pollution and to develop strategies to keep this pollution away.

关键词： central air conditioning microbe bacteria fungi contamination field experiment

Removal of Cr (VI) from Aqueous Solution Using Ultrafine Coal Fly Ash

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Journal of Wuhan university of technology(Materials Science) 2010年第2期25卷 323-327页

作者：刘转年 College of Geology and Environment Xi'an University of Science and Technology

Coal fly ashes WSRA and BQRA were ball milled for 5 h to produce their ultrafine coal fly ashes WSUA and BQUA, respectively. Batch kinetic, isotherm and pH effect on adsorption were studied to evaluate removal of Cr （VI） from aqueous solutions by ultrafine coal fly ashes comparing with raw coal fly ashes. The kinetics of adsorption indicates the process to be intraparticle diffusion controlled and follows the Lagergren first-order kinetics for all coal fly ashes. The first-order rate constants （k1） of Cr （VI） adsorption onto WSRA, WSUA, BQRA and BQUA are 1.981, 1.497, 2.119 and 1.500 （×10^-2） min^-1, respectively. The adsorption capacities of WSUA and BQUA are much better than those of WSRA and BQRA. Equilibrium adsorption data of all coal fly ashes well satisfy the Langmuir isotherm. The adsorbed amounts of Cr （VI） onto WSUA and BQUA decrease from pH 2 to pH 6 and then increase up to pH 12.

关键词： ultrafine coal fly ash Cr (VI) adsorption wastewater treatment

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液压油载体净化的理论与实验研究

煤炭学报 1997年第1期22卷 94-97页

作者： Zhang xi(university of Science and technology Beijing) 北京科技大学

通过对污染液压油表面特性的分析，认为污染油液具有很强的表面活性，依此提出了液压油载体净化理论，进行了液压油载体净化的实验室试验．试验结果证明，污染液压油净化后的主要理化指标达到了新油水平．

关键词：液压油载体净化污染液压油矿山机械

ON THE CALCULATION OF FLOW OVER AND THROUGH A ROCK-FILL DAM

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Journal of Hydrodynamics 1999年第1期11卷 1-10页

作者： Liu Fa-quan (xi’an university of technology, xi’an 710048, P. R. China )

For an overtopped rock-fill dam, the flow field consists of open flow and seepage flow, which have different properties. The overflow is characterized as variable flow and the seepage flow is not the Darcy flow, but non-Darcy flow. For the analysis of the flow characters, using the energy theory and the FEM, the author presents a method to calculate the combined flow (i. e. flow over and through a dam ) in this paper. The experimental work shows that, the calculated results agree well with the experimental ***, it is not only possible, but also feasible to solve this problem with the presented method.

关键词： overtopped flow seepage flow,rock-fill dam non-Darcy flow

Allocation of power generating and shipping of Hanjiang upstream cascade

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Progress in Natural Science:Materials International 2005年第8期15卷 733-741页

作者： LIU Junping1* and CHANG Mingqi 2,3(1. School of Civil Engineering and Architecture, Zhejiang university of technology, Hangzhou 310014, China 2. Institute of Water Resources & Hydroelectric Engineering, xi'an university of technology, xi'an 710048, China 3. Shanxi Institute of Water Resources, Taiyuan 030001, China) School of Civil Engineering and Architecture Zhejiang University of Technology Hangzhou 310014 China. Institute of Water Resources & Hydroelectric Engineering Xi'' an University of Technology Xi'' an 710048 China. Shanxi Institute of Water Resources Taiyuan 030001 China

The optimal model and simulating model of the Hanjiang cascade reservoirs operation with one day as its calculating period are established to coordinate the contradictions between power generating and shipping. The optimal model is solved by progressive optimality algorithm method adopting the theory of large system decomposing and coordinating. By analyzing the water allocation results obtained from six schemes, which are two cascades, four cascades and seven cascades joint operation considering shipping or not, the contradiction degree between power generating and shipping is investigated and some joint operation schemes are proposed.

关键词： cascade power generating contradiction shipping optimal operation.

A mathematical model for concept granular computing systems

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Science China(Information Sciences) 2010年第7期53卷 1397-1408页

作者： QIU GuoFang1, MA JianMin2, YANG HongZhi3 & ZHANG Wenxiu3 1School of Management, xi’an university of Architecture & technology, xi’an 710055, China 2Faculty of Science, Chang’an university, xi’an 710064, China 3Faculty of Science, xi’an Jiaotong university, xi’an 710049, China School of Management Xi"an University of Architecture & Technology Faculty of Science Chang"an University Faculty of Science Xi"an Jiaotong University

Extent-intent and intent-extent operators are introduced between two complete lattices in this paper and a mathematical model for concept granular computing system is established. We proved that the set of all concepts in this system is a lattice with the greatest element and the least element. This framework includes formal concept lattices from formal contexts, L fuzzy concept lattices from L fuzzy formal contexts and three kinds of variable threshold concept lattices, i.e. the extension and the intension of a concept are a crisp set and a crisp set, a crisp set and a fuzzy set, a fuzzy set and a crisp set, respectively. Finally, some iterative algorithms for constructing concepts are proposed and they are proved to be optimal concepts under some conditions in this system.

关键词： granular computing formal concept analysis concept lattice mathematical model

Effects of Nitrogen Doping on Microstructure and Photocatalytic Activity of Nanocrystalline TiO_2 Powders

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Journal of Wuhan university of technology(Materials Science) 2007年第3期22卷 457-461页

作者：杨志远 Dept. of Chemistry and Chemical Engineering Xi’an University of Science and Technology

Nitrogen-doped TiO2 nanocrystalline powders were prepared by hydrolysis of tetrachloride titanium （TiCl4） in a mixed solution of ethanol and ammonium nitrate （NH4NO3） at ambient temperature and atmosphere followed by calcination at 400 ℃ for 2 h in air. FTIR spectra demonstrate that amine group in original gel is eliminated by calcination, and the TiO2 powder is liable to absorb water onto its surface and into its capillary pore. XRD and SEM results show that the average size of nanocrystalline TiO2 particles is no more than 60 nm and with increasing the calcination temperature, the size of particles increases. XPS studies indicate the nitrogen atom enters into the TiO2 lattice and occupies the position of oxygen atom. The nitrogen doping not only depresses the grain growth of TiO2 particles, but also reduces the phase transformation temperature of anatase to futile. The photocatalytic activity of the nitrogen-doped TiO2 powders has been evaluated by experiments of photocatalytic degradation aqueous methylene blue.

关键词： titanium oxide nitrogen doping photocatalytic activity nanocrystalline methylene blue