检索结果-南通市图书馆

Optimization of spray conditions in cold spraying based on numerical analysis of particle velocity

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 43-48页

作者： LI Wen-ya LI Chang-jiu State Key Laboratory for Mechanical Behavior of Materials Xi''an Jiaotong University Xi''an 710049 China State Key Laboratory for Mechanical Behavior of MaterialsXi''an Jiaotong University Xi''an 710049 China

The effects of the parameters involved in cold spray on the acceleration of particles are systematically investigated by a CFD code in order to reveal the main factors influencing significantly particle velocity. The parameters involved include nozzle geometry parameters, processing parameters and properties of spray particles. It is found that driving gas type, operating pressure and temperature are main processing parameters which influence particle velocity. As for nozzle geometry, the expansion ratio and divergent section length of spray gun nozzle show significant effects. Moreover, the density, size and morphology of powder also have significant effects on particle velocity. The effects of those main parameters are summarized in a comprehensive equation obtained through nonlinear regression of the simulated results for the estimation of particle velocity. The interactions of the parameters on particle acceleration can be examined through the equation. Moreover, the optimization of the dimensions of spray gun nozzle and spray parameters can be realized based on the obtained results.

关键词： cold spraying numerical modeling particle acceleration impact velocity

Microstructure evolution of cold-sprayed coating during deposition and through post-spraying heat treatment

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 49-54页

作者： LI Chang-jiu LI Wen-ya State Key Laboratory for Mechanical Behavior of Materials Xi''an Jiaotong University Xi''an 710049 China State Key Laboratory for Mechanical Behavior of Materials Xi''an Jiaotong University Xi''an 710049 China

The microstructural features of cold-sprayed coatings were investigated using Cu, Ti and Zn feedstocks by optical microscopy, scanning electron microscopy and transmission electron microscopy to reveal the microstructure evolution mechanisms in cold spray. Four typical effects including tamping, refinement, impact-induced fusion and annealing were examined on microstrueture. It is found that the microstructure of cold spray coating is remarkably influenced by spray materials. Ti coatings consist of evident porous layer and Cu coatings present a limited porous layer only near the surface. It is clear that the successive tamping effect and dynamic refinement of grains significantly influence the microstructure evolution of cold-sprayed coating. The tamping effect leads to the densification of porous coating layer gradually and the refinement effect leads to the formation of fine microstructure. It is considered that the large difference in the formation of porous layer is attributed to the dynamic impact pressure and hardenability of materials. It is also found that the impact-induced fusion during deposition of Zn coating can also modify the interfacial microstructure between particles in cold spray coating. Moreover, the nanocrystalline phase can be formed at the interfaces among particles resulting from the localized melting of the interfaces and tamping effect. Furthermore, the annealing treatment can modify the microstructure and property of a cold-sprayed coating.

关键词： cold spraying coating microstructure evolution annealing treatment

Effects of surface oxide species and contents on SiC slurry viscosity

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2005年第3期24卷 240-245页

作者： NING Shufan LI Hongyan CHEN Wei LIU Bin CHEN Shoutian State Key Laboratory of Electrical Insulation for Power Equipment Xi＇an Jiaotong University Xi＇an 710049 China School of Technology Physics Xidian University Xi＇an 710071 China

The disadvantageous effects of colloidal SiO2 layer and micro-content of metal oxide adsorbed on SiC powder surface on SiC slurry stable dispersion were studied, and the novel method to avoid this disadvantage was proposed. By acidwashing, on the one hand, because the maximum Zeta potential of SiC powder increases to 72.49 mV with the decreasing content of metal oxide adsorbed on the SiC powder surface, the repulsion force between SiC powders that dispersed in slurry is enhanced, thus the SiC powder can be fully dispersed in slurry. On the other hand, after HF acidwashing, with the OH^- group adsorbed on SiC powder surface destroyed and replaced by the Fion, the hydrogen bond adsorbed on the OHgroup is also destroyed. Therefore, the surface property of the SiC powder is changed from hydrophilic to hydrophobic; H2O that adsorbed on SiC powder surface is released and can flow freely, and it actually increases the content of the effective flow phase in the slurry. These changes of SiC powder surface property can be proved by XPS and FTIR analysis. Finally, the viscosity of SiC slurry is decreased greatly, and when the viscosity of the slurry is lower than 1 Pa·s, the solid volume fraction of SiC powder in the slurry is maximized to 61.5 vol.%.

关键词： SiC powder water base slurry acidwashing surface oxide Zeta potential hydrophobic slurry viscosity

A novel methodology for finding the regulation on gene expression data

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2009年第2期19卷 267-272页

作者： Jarka Glassey Elaine Martin School of Chemical Engineering and Advanced Materials University of Newcastle upon TyneMerz Court

DNA microarray technology is a high throughput and parallel technique for genomic investigation due to its advantages of simul-taneously surveying features of large scales complex data in biology. This paper aims to find feature subset to build the classifier for gene expression data analysis. At first,K-means clustering algorithm was carried out on the dataset of yeast cell cycle. Based on Rand cal-culation,a statistical method was used to pick out the data points (genes) for classifier design. Meanwhile,the principal component anal-ysis was applied to help to construct the classifier. For the validation of classifier built and prediction of a target subset of genes,discriminant analysis in terms of partial least square regression and artificial neural network were also performed.

关键词： Classifier design Discriminant analysis Gene expression data Rand calculation

NUMERICAL SIMULATION OF ULTRASONIC NONDESTRUCTIVE TESTING FOR WELDS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 38-42页

作者： H.D.Chen Y.W.Wang J.Xue Welding Research Institute Xi'an Jiaotong University Xi'an 710049 ChinaWelding Research Institute Xi'an Jiaotong University Xi'an 710049 ChinaWelding Research Institute Xi'an Jiaotong University Xi'an 710049 China

A computer simulation technique for ultrasonic propagation is utilized for the simulation of ultrasonic nondestructive testing (NDT). In this paper, one goal of the simulation is to compute ultrasonic field radiated by arbitrary transducers into pieces under examination. The other simulates a testing experiment. The simulation approach is based on the model for the computation of the ultrasonic field in isotropic media radiated from actual NDT transducers. After the field is known, remaining to be modeled is the interaction between this field and the scatters (defect) and the echo structure. The model of beam-defect interaction is based on the Kirchhoff’s diffraction approximations theory applied to elastodynamics. We assumed that the incident wave fronts on the defect are plane in the case of a focused immersed transducer and material is isotropic and homogeneous. The simulating results demonstrate that the model in ultrasonic NDT of welds is practical in further research and useful in optimizing testi

关键词： ultrasonic testing modeling welds numerical simulation

Influence of characteristics of stabilized zirconia electrolyte on performance of cermet supported tubular SOFCs

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第Z1期25卷 273-279页

作者： LI Changjiu LI Chengxin xiNG Yazhe xiE Yingxin LONG Huiguo State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi''an Jiaotong UniversityXi''an 710049China

Ni-Al_(2)O_(3)cermet supported tubular SOFC was fabricated by thermal ***-sprayed Al_(2)O_(3)-Ni cermet coating plays dual roles of a support tube and an anode current collector.4.5mol.%yttria-stabilized zirconia(YSZ)and 10mol.%scandia-stabilized zirconia(ScSZ)coatings were deposited by atmospheric plasma spraying(APS)as the electrolyte in present *** electrical conductivity of electrolyte was measured using DC *** post treatment was employed using nitrate solution infiltration to densify APS electrolyte layer for improvement of gas *** electrical conductivity of electrolyte and the performance of single cell were investigated to optimize SOFC *** electrical conductivity of the as-sprayed YSZ and ScSZ coating is about 0.03 and 0.07 S·cm^(-1)at 1000℃,*** ohmic polarization significantly influences the performance of *** maximum output power density at 1000℃increases from 0.47 to 0.76 W·cm^(-2)as the YSZ electrolyte thickness reduces from 100μm to 40μ*** APS ScSZ coating of about 40μm as the electrolyte,the test cell presents a maximum power output density of over 0.89 W·cm^(-2)at 1000℃.

关键词： solid oxide fuel cells(SOFCs) plasma spraying yttria-stabilized zirconia(YSZ) scandia-stabilized zirconia(ScSZ) coating

Effects of Xe Gas Content and Total Gas Pressure on the Discharge Characteristics of Colour Plasma Display Panels

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2006年第4期8卷 447-450页

作者：胡文波韩梦驹梁志虎 Key Laboratory for Physical Electronics and Devices of the Ministry of Education Xi'an Jiaotong UniversityXi'an 710049China

The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag （DTL）, discharge current peak, and full-width-at-half-maximum （FWHM） of the discharge current pulse, are experimentally studied. The results indicate that as the Xe gas content in the He-Ne-Xe gas mixture or total pressure increases, the sustaining voltage margin increases, the white-field chromaticity improves, and the discharge current peak has a maximum value, while DTL and FWHM have a minimum value. The mean electron energy in the gas mixture discharge is also calculated through a numerical solution of Boltzmann equation. The experimental results are explained from a view of the mean electron energy variations with the Xe gas content and total gas pressure.

关键词： plasma display panel gas mixture discharge characteristic sustaining voltage margin discharge time lag

On the 2k-th Power Mean of Inversion of L-functions with the Weight of the Gauss Sum

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2004年第1期20卷 175-180页

作者： YuanYI WenPengZHANG ResearchCenterforBasicScience Xi'anJiaotongUniversityXi'an710067P.R.China ResearchCenterforBasicScience Xi'anJiaotongUniversityXi'an710067P.R.China

The main purpose of this paper is to use the estimate for character sums and the method of trigonometric sums to study the 2k-th power mean of the inversion of Dirichlet L-functions with the weight of the Gauss sums, ... 详细信息

关键词： Dirichlet L-functions Gauss sums Mean value Asymptotic formula

Construction and identification of recombinant vectors carrying herpes simplex virus thymidine kinase and cytokine genes expressed in gastric carcinoma cell line SGC7901

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2004年第1期10卷 26-30页

作者： Jian-HuaZhang Ming-xiWan Jia-YingYuan Bo-RongPan DepartmentofBiomedicalEngineering SchoolofLifeScienceandTechnologyXi'anJiaotongUniversity28WestXianningRoadXi'an710049ShaanxiProvinceChina DepartmentofUltrasonicDiagnosis XijingHospitalFourthMilitaryMedicalUniversity127WestChangleRoadXi'an710033ShaanxiProvinceChina DepartmentofOncology XijingHospitalFourthMilitaryMedicalUniversity127WestChangleRoadXi'an710033ShaanxiProvinceChina DepartmentofBiomedicalEngineering SchoolofLifeScienceandTechnologyXi'anJiaotongUniversity28WestXianningRoadXi'an710049ShaanxiProvinceChina

AIM: To construct and identify the recombinant vectors carrying herpes simplex virus thymidine kinase (HSV-TK) and tumor necrosis factor alpha (TNF-α) or interleukin-2 (IL-2) genes expressed in gastric carcinoma cell line SGC7901. METHODS: The fragments of HSV-TK, internal ribosome entry sites (IRES) and TNF-α or IL-2 genes were inserted in a TK-IRES-TNF-α or TK-IRES-IL-2 order into pEGFP-N3 and pLXSN to generate the therapeutic vectors pEGFP-TT,pEGFP-TI, pL(TT)SN and pL(TI)SN respectively, which were structurally confirmed by the digestion analysis of restriction endonuclease. The former two plasmids were used for the transient expression of recombinant proteins in the target cells while pL(TT)SN and pL(TI)SN were transfected into SGC7901 cells by lipofectamine for the stable expression of objective genes through G418 selection. The protein products expressed transiently and stably in SGC7901 cells by the constructed vectors were confirmed by fluorescent microscopy and Western blot respectively. RESULTS: The inserted *** in all constructed plasmids were structurally confirmed to be consistent with that of the published data. In the transient expression, both pEGFP-TT and pEGFP-TI were shown expressed in nearly 50% of the transfected SGC7901 cells. Similarly, the G418 selected vectors PL(TT)SN and PL(TI)SN were confirmed to be successful in the stable expression of the objective proteins in the target cells. CONCLUSION: The constructed recombinant vectors in the present study that can express the suicide gene TK in combination with cytokines genes may serve as the potential tools to perform more effective investigations in future for the gene therapy of gastric carcinoma.

关键词：胃癌单纯性疱疹病毒胸腺密啶核苷激酶细胞因子 SGC7901细胞肿瘤坏死因子