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Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool

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Journal of materials science & Technology 2005年第3期21卷 408-414页

作者： Yuzhen ZHAO, Yongping LEI and Yaowu SHI school of materials {2. and engineering, Beijing university of Technology, Beijing 10002., china school of materials {2. and engineering Beijing University of Technology Beijing 100022 China

A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 × 10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 12.×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 2.-150×10-6.

关键词： Surface-active elements Sulfur Plow patterns Depth/width

One-pot synthesis of crystalline SnO_2.nanoparticles and their low-temperature ethanol sensing characteristics

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1601-1605页

作者： CHEN YuJin1,2.3,ZHU ChunLing4,WANG LiJiao3 & WANG TaiHong2.1 school of materials {2. and engineering,Beijing Institute of Technology,Beijing 100081,china 2.Micro-Nano Technologies Research Center,Hunan university,Changsha 410082.china 3 College of {2.,Harbin engineering university,Harbin 150001,china 4 College of Material {2. and Chemical engineering,Harbin engineering university,Harbin 150001,china school of materials {2. and engineering Beijing Institute of Technology Beijing 100081 China Micro-Nano Technologies Research Center Hunan University Changsha 410082 China College of science Harbin Engineering University Harbin 150001 China College of Material science and Chemical engineering Harbin Engineering University Harbin 150001 China

Crystalline SnO2.nanoparticles(NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic *** synthesized NPs can detect ethanol at a ppm level even at 100℃.Furthermore,the NPs have good selectivity to *** excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model.

关键词： SnO2 nanoparticles sensing characteristics

Fabrication of Porous Bulk Metallic Glass

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Journal of materials science & Technology 2005年第6期21卷 788-790页

作者： Keqiang QIU+ and Yinglei REN school of materials {2. and engineering, Shenyang university of Technology, Shenyang 11002., china school of materials {2. and engineering Shenyang University of Technology Shenyang 110023 China

An open-cell porous bulk metallic glass （BMG） with a diameter of at least 6 mm was fabricated by using an U-turn quartz tube and infiltration casting around soluble NaCI placeholders. The pore formation and glassy structure were examined by optical microscopy （OM）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the pores or cells are connected to each other and the specimen is composed of a mostly glassy phase. This paper provides a suitable method for fabrication of porous BMG and BMG with larger size in diameter.

关键词： Porous bulk metallic glass U-turn quartz tube Infiltration casting

Fabrication of pure copper rods containing continuous columnar crystals by continuous unidirectional solidification technology

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Journal of university of science and Technology Beijing 2004年第3期11卷 240-244页

作者： Hong zhang Jianxin Xie Zidong Wang materials science and {2. school, university of science and Technology Beijing, Beijing 100083, china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Pure copper rods containing continuous columnar crystals were fabricatedusing the downward CUS (Continuous Unidirectional Solidification) equipment. When the technologicalparameters were set as the ranges of mould temperature 1100-1300℃, cooling distance (the distancefrom the exit of the cast mould to the start point of cooling) 10-2. mm, casting speed 0.2.2.5 mm/s,cooling water (2.-2.℃) volume 1000-132. L/h, and when these parameters matched reasonably, the CUSprocess was performed stably, and pure copper rods containing continuous columnar crystals withbright and smooth surface were produced. The dendritic arm spacing of the crystals in copper rodsdecreased with increasing the casting speed. The results of the texture by X-ray diffractionanalysis showed that the rods has strong fiber texture.

关键词： copper continuous unidirectional solidification mould temperature castingspeed microstructure texture

A first-principles study of dihydroazulene as a possible optical molecular switch

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science china(Physics,Mechanics & Astronomy) 2011年第3期Mechanics & Astronomy) .卷 437-441页

作者： XIA CaiJuan1, LIU DeSheng2.3 & LIU HanChen1 1 school of science, Xi’an Polytechnic {2., Xi’an 710048, china 2.school of Physics, State Key Laboratory of Crystal materials, shandong {2., Jinan 2.0100, china 3 Department of Physics, Jining {2., Qufu 2.3155, china 1. school of science Xi’an Polytechnic University Xi’an 710048 China2. School of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China3. Department of Physics Jining University Qufu 273155 China

By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.

关键词： molecular switch nonequilibrium Green’s function electronic transport density functional theory

Real estate appraisal system based on GIS and BP neural network

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中国有色金属学会会刊：英文版 2011年第S3期21卷 626-630页

作者： LIU Xiao-sheng1, DENG Zhe1, WANG Ting-li2.1. school of Architecture and Survey engineering, Jiangxi {2. of science and Technology, Ganzhou 341000, china 2. school of Applied science, Jiangxi {2. of science and Technology, Ganzhou 341000, china [a] school of Architecture and Survey engineering Jiangxi University of Science and Technology Ganzhou 341000 China [b] school of Applied science Jiangxi University of Science and Technology Ganzhou 341000 China

For the inefficiency and inaccuracy of appraisal method of traditional estate appraisal theory, the real estate appraisal system based on GIS and BP neural network was established. The structure of the system was designed which includes appraisal model, trade case, GIS database and query analysis module. With the help of the L-M algorithm in MATLAB software, BP neural network was improved and the trade cases were trained, then the BP neural network which has already been trained was tested. At the same time, the BP neural and GIS were put together to construct the hedonic price estimate model. The C# and ArcGIS9.3 were used to achieve the system in VS2.08. City basic geographic data and real estate related information were used as the basic data in practice. The results show that the functions of querying, adding and editing the spatial data and attribute data are achieved and also the efficiency and accuracy of real estate are improved, so that the new method of real estate is provided by the system.

关键词： BP neural network GIS hedonic price real estate appraisal

Sustainable Intensification and Large-scale Operation of Cultivated Land Use at the Farmers’ Scale:A Case Study of shandong Province,china

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Chinese Geographical science 2024年第1期34卷 149-167页

作者： LI Li LYU Xiao ZHANG Anlu NIU shandong PENG Wenlong school of Public Administration Huazhong Agricultural UniversityWuhan430070China Department of Geography University of ZurichZurich8057Switzerland school of Humanities and Law Northeastern UniversityShenyang110169China school of Geography and Tourism Qufu Normal UniversityRizhao276800China

Sustainable intensification of cultivated land use(SICLU) and large-scale operations(LSO) are widely acknowledged strategies for enhancing agricultural ***,the existing literature has faced challenges in precisely defining SICLU and constructing comprehensive indicators,which has hindered the exploration of factors influencing LSO within the SICLU *** address this gap,we integrated self-efficacy theory into the design of an index framework for evaluating *** subsequently employed econometric models to analyze the significant factors that impact *** findings reveal that SICLU can be divided into four key dimensions:intensive management,efficient output,resource conservation,and ecological environment ***,it is crucial to incorporate belief-based cognitive factors into the index system,as farmers’ understanding of fertilizer and pesticide application significantly influences their willingness to engage in ***,we identify grain market turnover as the most influential factor in promoting LSO,with single-factor contribution rates reaching 70.9% for cultivated land transfer willingness and 62.5% for the total planting ***,unlike irrigation and agricultural machinery inputs,increased labor inputs correspond to larger planting areas for *** trend may be attributed to reduced labor availability because of rural labor migration,whereas the reduction in irrigation and agricultural input is contingent on innovations in production practices and the transfer of cultivated land management ***,SICLU dynamically influences LSO,with each index related to SICLU having an optimal range that fosters *** insights offer valuable guidance for policymakers,emphasizing farmers as their central focus,with the adjustment of input and output factors as a means to achieve LSO as the ultimate *** conclusion,we propose research avenues for further enriching the SICLU framework to ensur

关键词： sustainable intensification of cultivated land use(SICLU) self-efficacy status quo bias input and output Boosted Regression Tree willingness to transfer cultivated land cultivated land planting areas shandong,china

Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

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science china(Physics,Mechanics & Astronomy) 2006年第3期49卷 257-272页

作者： XU Mingyu1 & TAN Wenchang2.1. Institute of Applied Mathematics, school of Math & System science, {2. university, Jinan 2.0100, china 2. State Key Laboratory of Turbulence and Complex Systems & Department of Mechanics and engineering science, Peking university, Beijing 100871, china 1. Institute of Applied Mathematics School of Math & System Science Shandong University Jinan 250100 China 2. State Key Laboratory of Turbulence and Complex Systems & Department of Mechanics and engineering science Peking University Beijing 100871 China

From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equa- tions) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern me- chanics. Some authors’ researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

关键词： fractional operators,intermediate processes,critical phenomena,modern mechanics

Three-Dimensional and Cross-sectional Characteristics of Normal Grain Growth Based on Monte Carlo Simulation

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 129-133,139页

作者： Xiaoyan Song Guoquan Liu(Material science and engineering {2., university of science and Technology Beijing, Beijing 100083, china)(Department of materials science and engineering, Hebei university of Technology, Tianjin 300130, china) Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China Departments of materials science and {2. Hebei University of Technology Tianjin 300130 China

An appropriate Monte Carlo method was developed to simulate the three-dimensional normal grain growth more completely. Comparative investigation on the three-dimensional and the cross-sectional characteristics of normal grain growth was done. It was found that the time exponent of grain growth determined from cross-section exhibits the same rule of increasing slowly with time and approaching the theoretical value n = 0.5 of steadygrain growth as the three-dimensional (3-D) system. From change of the number of grains per unit area with timemeasured in cross-section, the state of 3-D normal grain growth may be predicted. The gtain size distribution incross-section is different from that in 3-D system and can not express the evolution characteristic of the 3-D distribution. Furthermore, there exists statistical connection between the topological parameters in cross-section and thosein three-dimensions.

关键词： Monte Carlo simulation normal grain growth three-dimension cross-section characteristics