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IGNITING shs BY LAsER AND ITs APPLIcATION TO sELEcTIVE LAsER sINTERING OF METALLIc POWDER MATERIAL

Acta Metallurgica sinica(English Letters) 2004年第5期17卷 694-704页

作者： Y.s.shi s.c.chen X.L.Lu s.h.huang stateKeyLaboratoryofPlasticFormingsimulationandDie＆MouldTechnology SchoolofMaterialScienceandEngineeringHuazhongUniversityofScienceandTechnologyWuhan430074China

how to directly fabricate metallic functional parts with selective laser sintering (sLs) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by use of sLs are analyzed. For the sake of solving the problems, a new idea of adding self-propagating high-temperature synthesis (shs) material into metallic powder material to form new type of sLs metallic powder material is put forward. This powder material can release controllable amount of heat during its interaction with the laser beam energy to reduce the requirement to laser power during directly sintering metallic part, to prolong the time of metallic liquid phase existing, and to improve the intensity and accuracy of sLs part. For this reason, shs material′s interaction with the cO2 laser beam energy is researched, which proves that cO2 laser beam energy may instantly ignite shs reaction. On the basis of the above-mentioned researches, the effect of sintering the metal powder material mixing shs material with cO2 laser is also researched, which shows: there is an optimal blending ratio of various material in the new metallic powder material. Under the optimal blending ratio and sLs process parameters, this new metallic powder material can indeed release amount of heat and shs reaction may be controlled within the laser sintering. This research result makes it possible that the metallic part is directly sintered with small cO2 laser (less than 50W), which may greatly reduce the volume, cost and running expenditure of sLs machine, be propitious to application.

关键词： selective laser sintering (sLs) self-propagating high-temperaturesynthesis (shs) ignition time metallic powder material,metallic part

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Effects of displacement boundary conditions on thermal deformation in thermal stress problems

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china Foundry 2013年第3期10卷 187-194页

作者： s.Y.Kwak c.h.Lim J.h.Nam e-Design center Korea Institute of Industrial Technology Department of Virtual Engineering University of Science and Technology

Most computational structural engineers are paying more attention to applying loads rather than to DBcs （Displacement Boundary conditions） because most static stable mechanical structures are working under already prescribed displacement boundary conditions. In all of the computational analysis of solving a system of algebraic equations, such as FEM （Finite Element Method）, three translational and three rotational degrees of freedom （DOF） should be constrained （by applying DBcs） before solving the system of algebraic equation in order to prevent rigid body motions of the analysis results （singular problem）. however, it is very difficult for an inexperienced engineer or designer to apply proper DBcs in the case of thermal stress analysis where no prescribed DBcs or constraints exist, for example in water quenching for heat treatment. Moreover, improper DBcs cause incorrect solutions in thermal stress analysis, such as stress concentration or unreasonable deformation phases. To avoid these problems, we studied a technique which performs the thermal stress analysis without any DBcs; and then removes rigid body motions from the deformation results in a post process step as the need arises. The proposed technique makes it easy to apply DBcs and prevent the error caused by improper DBcs. We proved it was mathematically possible to solve a system of algebraic equations without a step of applying DBcs. We also compared the analysis results with those of a traditional procedure for real castings.

关键词： thermal stress analysis displacement boundary conditions rigid body motion singular problem

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Physical properties of sprayed antimony doped tin oxide thin films:The role of thickness

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Journal of semiconductors 2011年第5期32卷 10-17页

作者： A.R.Babar s.s.shinde A.V.Moholkar c.h.Bhosale J.h.Kim K.Y.Rajpure Electrochemical Materials Laboratory Department of PhysicsShivaji UniversityKolhapur-416 004India Department of Materials science and Engineering Chonnam National University300 Yongbong-DongBuk-GuGwangju500-757South Korea

Transparent conducting antimony doped tin oxide （sb：snO2） thin films have been deposited onto pre- heated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structural, morphological, X-ray photoelectron spectroscopy, optical, photoluminescence and electrical properties of these films have been studied. It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the （211） and （112） planes. Polyhedrons like grains appear in the FE-sEM images. The average grain size increases with increasing spraying quantity. The compositional analysis and electronic behaviour of sb：snO2 thin films were studied using X-ray photoelectron spectroscopy. The binding energy of sn3ds/2 for all samples shows the sn^4＋ bonding state from snO2. An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by sb^5＋ ions. The film deposited with 20 cc solution shows 70 % transmittance at 550 nm leading to the highest figure of merit （2.11 × 10^-3 Ω^-1）. The resistivity and carrier concentration vary over 1.22 × 10^-3 to 0.89 × 10^-3Ω cm and 5.19 ×10^20 to 8.52 × 10^20 cm^-3, respectively.

关键词： semiconductors microstructure optical properties electrical properties

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A Finite Element Method for Modelling Electromechanical Wave Propagation in Anisotropic Piezoelectric Media

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communications in computational Physics 2007年第2期2卷 271-292页

作者： s.Rahman h.P.Langtangen c.h.W.Barnes cavendish Laboratory Cambridge UniversityJ J Thomson AvenueCambridgeCB3 OHEUnited Kingdom simula Research Laboratory Martin Linges v 17Fornebu P.O.Box 1341325 LysakerNorway

We describe and evaluate a numerical solution strategy for simulating surface acoustic waves(sAWs)through semiconductor devices with complex *** multi-physics problem is of particular relevance to the design of sAW-based quantum electronic *** mathematical model consists of two coupled partial differential equations for the elastic wave propagation and the electric field,respectively,in anisotropic piezoelectric *** equations are discretized by the finite element method in space and by a finite difference method in *** latter method yields a convenient numerical decoupling of the governing *** describe how a computer implementation can utilize the decoupling and,via object-oriented programming techniques reuse independent codes for the Poisson equation and the linear time-dependent elasticity *** we apply the simulator to a simplified model problem for verifying the implementation,and thereafter we show that the methodology is capable of simulating a real-world case from nanotechnology,involving sAWs in a geometrically non-trivial device made of Gallium ***:***,***,*** Key words:Finite element method,piezoelectric surface acoustic waves,Gallium Arsenide.

关键词： Finite element method piezoelectric surface acoustic waves Gallium Arsenide.

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Electrochemical response of Nd3+ ions containing lithium borate glasses

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Journal of Rare Earths 2017年第5期35卷 480-484页

作者： D.D.Ramteke h.c.swart R.s.Gedam Department of Physics University of the Free State Department of Applied Physics Visvesvaraya National Institute of Technology

The present investigation was to understand the electrical properties of 27.5 Li2O-（72.5–x） B2O3-xNd2O3with x=0.5, 1, 1.5 and 2 glasses. We analyzed the impedance data for a wide frequency range to get inside the conduction phenomenon. The conductivity of the glasses decreased due to the decrease in the mobility of mobile Li+ions. This decrease was due to polymerization of glass network caused by the Nd3+ions. Modulus formalism confirmed that the Li+ions overcame the same barrier no matter whether it took part in the conduction process or relaxation process. scaling of the electrochemical data showed that conduction process in the ion conducting glasses was composition dependent and not the temperature dependent.

关键词： glasses impedance spectroscopy electrical properties modulus formalism scaling rare earths

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Novel AR-based interface for human-robot interaction and visualization

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Advances in Manufacturing 2014年第4期2卷 275-288页

作者： h.c.Fang s.K.Ong A.Y.c.Nee Department of Mechanical Engineering Faculty of EngineeringNational University of Singapore9 Engineering Drive 1Singapore 117576Singapore

Intuitive and efficient interfaces for human- robot interaction （hRI） have been a challenging issue in robotics as it is essential for the prevalence of robots supporting humans in key areas of activities. This paper presents a novel augmented reality （AR） based interface to facilitate human-virtual robot interaction. A number of human-virtual robot interaction methods have been for- mulated and implemented with respect to the various types of operations needed in different robotic applications. A Euclidean distance-based method is developed to assist the users in the interaction with the virtual robot and the spatial entities in an AR environment. A monitor-based visualization mode is adopted as it enables the users to perceive the virtual contents associated with different interaction methods, and the virtual content augmented in the real environment is informative and useful to the users during their interaction with the virtual robot. case researches are presented to demonstrate the successful implementation of the AR-based hRI interface in planning robot pick-and-place operations and path following operations.

关键词： human-robot interaction (hRI) human-robot interface Augmented reality (AR)

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Interface dominated deformation transition from inhomogeneous to apparent homogeneous mode in amorphous/amorphous nanolaminates

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Journal of Materials science & Technology 2022年第4期99卷 178-183页

作者： Z.Q.chen M.c.Li J.s.cao F.c.Li s.W.Guo B.A.sun h.B.Ke W.h.Wang songshan Lake Materials Laboratory Dongguan 523808PR China Institute of Physics Chinese Academy of SciencesBeijing 100190PR China Institute of Materials Engineering Nanjing UniversityNantong 226019PR China school of Physics science and Technology Xinjiang UniversityXinjiang 830046PR China school of Physical sciences University of Chinese Academy of SciencesBeijing 100049PR China state Key Laboratory for Mechanical Behavior of Material Xi'an Jiaotong UniversityXi’an 710049PR China

The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical ***,the plastic deformation mechanism of A/ANLs have yet been ***,we systematically examined the mechanical properties and deformation behavior of series of NiNb/ZrcuNi Al A/ANLs via nanoindentaion *** was found that both the amount and morphology of amorphous/amorphous interface(A/AIs)played crucial roles in the plastic deformation of A/*** and straighter A/AIs facilitated multiple shear banding deformation,of which the hardness increased with decreasing layer thickness,as the A/AIs hindered the propagation of shear bands(sBs).Whilst,more and wavier A/AIs promoted homogeneous deformation,of which the hardness stayed at a much lower value and was relatively irrelevant with the layer thickness,for the promoted activation of shear transformation zones by A/*** results provide guidance for modifying the mechanical properties of amorphous alloys with interface engineering design.

关键词： Amorphous alloys Nanolaminates shear bands hardness Interface

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Influence of austenization temperature on the erosion behavior of austempered ductile irons

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Journal of University of science and Technology Beijing 2008年第1期15卷 29-33页

作者： L.c. chang L c. hsui L.h. chen s.T. Lui Department of Mechanical Engineering Technology and Science Institute of Northern Taiwan Taipei 112 China Talpei Department of Materials science and Engineering Cheng-Kung University Talnan 800 China Taipei

The erosion behavior of austempered ductile irons austenized at different temperatures was studied. The results indicate that the erosion rate well correlates with the mechanical properties. At high impact angles, increasing ductility and mechanical energy density results in decreasing erosion rate, whereas increasing hardness reduces the erosion rate at low impact angles. 2008 University of science and Technology Beijing. All rights reserved.

关键词： austempered ductile iron erosion mechanical properties austenization

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Using sPOT 5 fusion-ready imagery to detect chinese tamarisk(saltcedar)with mathematical morphological method

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International Journal of Digital Earth 2014年第3期7卷 217-228页

作者： Q.s.Liu G.h.Liu c.huang c.J.Xie state Key Laboratory of Resources and Environmental Information system Institute of Geographic Science and Natural Resources ResearchChinese Academy of SciencesBeijingChina

chinese tamarisk(saltcedar)is a deciduous shrub that occurs widely across the Yellow River Delta in *** spatial structure of chinese tamarisk is believed to have an influence on the landscape and habitats of rare *** this study,first,chinese tamarisk is detected using canny edge detector and mathematical morphological operators based on sPOT 5 fusion-ready *** the numbers,areas,locations,and patch spacing of chinese tamarisk patches are *** experiments show that the detection accuracy of chinese tamarisk patches is about 93.4%after the disconnection of connected *** distribution orientation of about 70%of the patches is approximately *** 91%of the minimum distances among the patches are between 12.5 and 57.5 *** rose graph indicates that the main azimuth between patches is north--northwest,and the second is northeast and *** present study indicates that the integrating canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting chinese tamarisk patches and is easy to identify the spatial structure of chinese tamarisk patches,which reduces the time and labor for the visual interpretation of chinese tamarisk patches.

关键词： sPOT 5 chinese tamarisk spatial structure mathematical morphology patch

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Influence of carrier Gas on Analysis of MgO Powders by Laser Ablation Inductively coupled Plasma Mass spectrometry

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Journal of Materials science & Technology 2009年第3期25卷 333-335页

作者： J.s. Lee Y.s. Lee c.J. Park h.s. Lee D.s. Lee Department of chemistry Yonsei University Material Analysis Team Korea Testing Laboratory Korea Research Institute of standards and science school of Material science and Engineering Pusan National Univirsity

Laser ablation inductively coupled plasma mass spectrometry （LA-IcP-Ms） has been widely adopted for the direct multi-elemental analysis with high sensitivity. Especially analysis of fine ceramics by LA-IcP-Ms without time-consuming sample decomposition process has been one of the most expecting application field. small additive elements in MgO powders were analyzed by LA-IcP-Ms. For precise and accurate analysis influence of carrier gas （Ar or he） was presented by the signal intensities of IcP-Ms, relative standard deviation of signal intensities and ablated particle size distribution. Ablated particles were collected and analyzed by scanning electron microscopy （sEM） to investigate the particle size distribution, and the ablated sample surface was examined by camscope. In he gas atmosphere, the signal was more stable than in Ar gas atmosphere. The signal intensity was higher in Ar than in he. Examination of ablated particles and sample surface reveals that more particles were generated in Ar atmosphere and the distribution of particle size was larger.

关键词： Laser ablation MgO powders carrier gas IcP-Ms

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