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Simulation on the Melt Flow in Laser Full Penetration Welding with a Model Including a Non-Rotational Symme-try Keyhole Based on Energy Balance

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稀有金属材料与工程 2011年第S4期40卷 120-124页

作者： Zhang L J1,Zhang J X1,Wu B1,2.Chen L2.Gong S L2.Wang H R3 1 State Key Laboratory of Mechanical Behavior for materials,xi’an jiaotong {2.,xi’an 710049,china2.Power Beam Processing Dept.,Avic Beijing Aeronautical Manufacturing Technology Research Institute,Beijing 10002.,china3 school of Energy and Power engineering,xi’an jiaotong {2.,xi’an 710049,china xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China xi An Jiao Tong Univ State Key Lab Mech Behav Mat Xian 710049 Peoples R China Avic Beijing Aeronaut Mfg Technol Res Inst Power Beam Proc Dept Beijing 100024 Peoples R China

A three dimensional model including a non-rotational symmetry keyhole of which the geometry is calculated base on the energy balance at keyhole wall is created to simulate the heat transfer and fluid flow within the molten pool during laser full penetration welding of titanium alloy *** order to take into account the effects of multiple reflections within the keyhole,a ray tracing method is employed and the coordinate dependent heat flux obtained is exerted on keyhole wall during the simulation on the heat transfer and fluid flow within molten ***,the computed weld cross sectional profile is compared with the experimental result to verify the model and it is fond that the simulation result is consists with experimental result.

关键词： laser welding titanium alloy non-rotational symmetry keyhole simulation

One-step conversion of methane and formaldehyde to ethanol over SA-FLP dual-active-site catalysts: A DFT study

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Chinese Chemical Letters 2024年第4期35卷 544-548页

作者： Tao Ban xi-Yang Yu Hai-Kuo Tian Zheng-Qing Huang Chun-Ran Chang Shaanxi Key Laboratory of Energy Chemical Process Intensification School of Chemical Engineering and TechnologyXi'an Jiaotong UniversityXi'an 710049China Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization School of Chemistry and Chemical EngineeringYulin UniversityYulin 719000China

One-step conversion of methane and formaldehyde into ethanol is a 100% atom-efficient process for carbon resources utilization and environment protection but still faces eminent challenges due to the lacking of efficient catalysts. Therefore, developing active and stable catalysts is crucial for the co-conversion of methane and formaldehyde. Herein, twelve kinds of “Single-Atom”-“Frustrated Lewis Pair”(SA-FLP)dual-active-site catalysts are designed for the direct conversion of methane and formaldehyde to ethanol based on density functional theory(DFT) calculations and microkinetic simulations. The results show that the SA-FLP dual active sites can simultaneously activate methane at the SA site and activate formaldehyde at the FLP site. Among the twelve designed SA-FLP catalysts, Fe1-FLP shows the best performance in the co-conversion of methane and formaldehyde to ethanol with the rate-determining barrier of 1.15 e *** is proved as the main product with the turnover frequency of 1.32.× 10^(-4)s^(-1)at 573 K and 3 *** work provides a universal strategy to design dual active sites on metal oxide materials and offers new insights into the effective conversion of methane and formaldehyde to desired C_(2. chemicals.

关键词： Single-atom Frustrated Lewis pairs Methane conversion Dual active sites Ethanol synthesis

Experimental Investigation on Local Air Age and Air Distribution of Stratum Ventilation

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湖南大学学报（自然科学版） 2009年第S1期36卷 35-39页

作者： WANG Feng-hao,LI Yuan-bin,LIU xiao-dong,WANG xin-ke(school of Human Settlements and Civil engineering,xi’an {2. university,xi’an,Shaanxi 710049,china) school of Human Settlements and Civil engineering Xi'an Jiaotong University Xi'an 710049 China

Because of the multiple problems on high energy consumption and unbalanced thermal comfort caused by the traditional ventilation system,a new concept of ventilation-stratum ventilation has been proposed,which sends the fresh air to the breathing zone *** this paper,the local air distributions of the displacement ventilation and the stratum ventilation in a model office were *** air ages in the breathing zone for the displacement ventilation and stratum ventilation were compared with the tracer gas concentration decay *** decay curves of tracer gas concentration for these two ventilation systems in the breathing zone were obtained,and the air ages were *** experimental results show that the stratum ventilation system can offer lower air age for four mechanically ventilated cases in the breathing zone,and it can also provide better thermal comfort,which renews the air of breathing zone more quickly and reduces the energy consumption in some *** experimental investigation provides a theoretical basis for the application of stratum ventilation system.

关键词： ventilation air quality air age distribution

RESIDUAL STRESS CONCENTRATION AND ITS EFFECTS ON FATIGUE LIMIT AND SHORT CRACK GROWTH

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Acta Metallurgica Sinica(English Letters) 1993年第2期6卷 96-100页

作者： HE Jiawen HU Naisai ZHANG Dingquan xi’an jiaotong university,xi’an,china Professor,Research Institute for Strength of Metals,xi’an {2. university,xi’an 710049,china xi'an jiaotong Univ Xi'an China

Residual stress concentration at a notch depends on both notch geometry and yield strength of the *** varies through the depth,and its magnitude may be higher than the theoretical *** *** concentration at the notch of shot-peened specimen of soft material is easily to he relaxed,with the surface damage during shot-peening results in a mi- nor contribution to the fatigue *** residual stress increases the crack closure effect at the notch and may lead to a non-propagating crack.

关键词： residual stress stress concentration fatigue

CONSTRAINTS ON THE CRACK TIP PLASTIC FIELDS UNDER LARGE SCALE YIELD

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Acta Mechanica Solida Sinica 2001年第2期14卷 138-146页

作者： Xu Fei~1 Guo Wanlin~(1,2. (1 State Key Laboratory of Mechanical Structure Strength and Vibration, xi’an jiaotong university, xi’an 710049,{2.) (2.school of Aeronautics and Astronautics,Nanjing university of Aeronautics and Astronautics, Nanjing 2.0016,{2.) State Key Laboratory of Mechanical Structure Strength and Vibration Xl'an Jiaotong University，Xi'an 710049，China State Key Laboratory of Mechanical Structure Strength and Vibration Xl'an Jiaotong University，Xi'an 710049，China school of Aeronautics and Astronautics Nanfing University of Aeronautics and Astronautics，Nanjing 210016，China

Plane strain elastic-plastic finite element analyses are used tostudy the stress, strain fields around a straight crack in powerhardening plastic material. Center crack panel (CCP), single edgecrack panel (SECP) and double edge crack panel (DECP) tensionspecimens are analyzed with various crack lengths. Two localconstraint parameters, i.e. in-plane stress ratio T_x andout-of-plane constraint T_z are an- alyzed, which are defined astangential stress dividing normal (open) stress and out-of-planestress dividing the sum of tangential stress and normal stressrespectively.

关键词： constraint in-plane stress ratio out-of-plane constraint

Construction of expression vector for NT4-ADNF-9 fusion gene

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Journal of Pharmaceutical Analysis 2009年第2期21卷 104-108页

作者： Guo-xi Zheng1,Kang Zhu1,Yang Jing1,Jun-rong Wei1,Hong-liang Zhu2.. Department of Otorhinolaryngology,the Second Affiliated Hospital,Medical school of xi’an jiaotong university,xi’an 710004 2. Medical school of xi’an jiaotong university,xi’an 710061,china. Department of Otorhinolaryngology Second Affiliated Hospital Medical School of Xi'an Jiao-tong University Xi'an 710004 China Medical school of xi'an jiaotong {2. Xi'an 710061 China

Objective To construct the prokaryotic expression vector bearing fusion gene NT4-ADNF-9 and lay foundation for further study on genetic therapy of neurosensory deafness. Methods By means of asymmetrical primer/ template,double stranded cDNA of activity dependent neurotrophic factor-9 (ADNF-9) was obtained,which included restriction enzymes sites on the two extremities. ADNF-9 cDNA was ligated to the signal and leader peptides of neurotrophin 4 (NT4),and the fusion gene was named NT4-ADNF-9. Then it was subcloned into prokaryotic expression vector pBV2.0,and called pBV2.0/ NT4-ADNF-9. Results Evidences of DNA sequence analysis and restriction enzymes digestion showed that we recombined ADNF-9 cDNA to the 3’terminal of the signal and leader peptides of NT4,and the fusion gene was subcloned into pBV2.0 successfully. Bioactivity of the products was proved that it could support the cell survival and neurite growth in the primary cultures of dorsal root ganglia (DRG) of embryonic day-8 chicken neurons as compared to the control. Conclusion Prokaryotic expression vector pBV2.0/NT4-ADNF-9 can be constructed successfully and the bioactivity is satisfactory.

关键词： activity dependent neurotrophic factor-9 neurotrophin 4 prokaryotic expression vector

MODULATED STRUCTURES AND ORDERING STRUCTURES IN ALLOYING AUSTENITIC MANGANESE STEEL

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Acta Metallurgica Sinica(English Letters) 2001年第2期14卷 148-152页

作者： L. He, Z.H. Jin and J.D. Lu (Department of Metallurgical engineering, Guizhou university of Technology, Guiyang 550003,{2.) (Institute of material Science and engineering, xi’an jiaotong university,xi’an 710049,{2.) Dept. of Metall. Eng. Guizhou Univ. of Technol. Guiyang 550003 China

The microstructure of Fe-10Mn-2.r-1.5C alloy has been investigated with transmission electron microscopy and X-ray diffractometer. The superlattice diffraction spots and satellite reflection patterns have been observed in the present alloy, which means the appearance of the ordering structure and the modulated structure in the alloy. It is also proved by X-ray diffraction analysis that the austenite in the alloy is more stable than that in traditional austenitic manganese steel. On the basis of this investigation, it is suggested that the C-Mn ordering clusters exist in the austenitic manganese steel and the chromium can strengthen this effect by linking the weaker C-Mn couples together, which may play an important role in work hardening of the austenitic manganese steel.

关键词： Aging of materials Austenite Crystal structure Manganese alloys Microstructure

Fast feature-based mode decision for 4×4 intra prediction in H.2.4/AVC

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Science china(Information Sciences) 2011年第11期54卷 2386-2399页

作者： WANG Ping,HUANG Hua & TAN Zhengschool of Electronic and Information engineering,xi’an {2. university,xi’an 710049,china 1. school of Electronic and Information engineering Xi’an Jiaotong University Xi’an 710049 China

Intra coding in H.2.4/AVC can significantly improve the compression efficiency at the cost of high computational complexity due to the use of the rate-distortion optimization *** reduce the complexity of intra prediction,we propose a feature-based mode decision algorithm for 4×4 intra *** algorithm is motivated by the fact that a good prediction mode usually has a small residue block,which is the difference between the original block and predicted *** sum of the absolute transformed coefficients and deviation information of residue block are used to measure the distortion of prediction mode and the smoothness of residue block,*** to the ranking of these two features of all possible modes,and together with the most probable mode,small numbers of candidate modes can be ***,the candidate modes are further reduced to only one by using two early termination rules based on the correlation of rank and most probable *** results demonstrate that the proposed mode decision method reduces about 60% of total encoding time of intra coding with negligible loss of coding performance.

关键词： intra prediction mode decision H.2.4/AVC RDO

Application of the Algorithm of Fractional Dimension to Extraction Image Edge

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稀有金属材料与工程 2006年第S3期 605-606页

作者： Qiang Luo~1 Qingli Ren~(2.3) (1.The Second Artillery engineering College,xi'an 71002.,china) (2.{2. of Technical Physics,xidian university,xi'an 710071,china) (3.xi'an jiaotong university,xi'an 710049,china)

The idea of fractional dimension was stated in brief ***,adopting the fractional statistical similar principle, the method of the least square minimum error was applied to evaluate the fractional dimension of per image pixel depending on the fractional property of *** the image edge is extracted by magnitude of fractional dimension of image *** presented the algorithm of the local fractional dimension,which made the rule of window size and sentencing the fractional dimension of *** this algorithm was waste time,it is better than the classical ones in extraction edge and anti-jamming.

关键词： fractional dimension image edge fractional Brownian random field