bluuebunny/crossref_metadata_2025 huggingface dataset:
Contour Controller Design for Two-Dimensional Stage System with Friction
Authors: Hsieh Chen , Lin K.C. , Chen Chieh Li
Published: March 2009

For multiple-axis stages, it is required to operate the axes simultaneously, such that the resulting trajectory of platform follows a given contour. For most stage systems, friction acts as the major disturbance which degrades the precision of system motion and its effect should be compensated. In this paper, contouring control of a two-dimensional stage system subjected to friction is investigated. A systematic contour controller design based on task coordinate frame is proposed and its effectiveness is studied through theoretical analysis and numerical simulations.
A 3D Slab Method in Cold Strip Rolling
Authors: Ren Hong Bin , Tieu A. Kiet , Lu Cheng , D'Alessio Giovanni
Published: March 2009

In this paper, a 3D slab method model has been developed. Two differential equations governing the longitudinal and transverse force equilibriums coupled with the Von Mises yield criterion have been solved to obtain the rolling pressure distribution. The strip speed is calculated according to the volume constancy. The Coulomb friction law with different frictional coefficient and speeds were applied to the longitudinal and transverse direction. Coupled with the roll stack
deformation model and thermal model, the developed 3D slab method model was used to predict the strip profile and edge drop. The effects of bending force, reduction and transverse friction on the strip profile and edge drop have been discussed in this paper. The calculated result predicted by the 3D slab
method is in very good agreement with measured results. The results have shown that the large bending force, small reduction and small friction will improve the strip profile and reduce the edge drop.
Influence of Casting Speed on Temperature and Flow Fields in Molten Pool during Twin-Roll Strip Casting Process
Authors: Zhang Xiao Ming , Jiang Zheng Yi , Liu Xianghua , Wang Guo Dong , Yang L.M. , Tieu A. Kiet
Published: March 2009

In twin-roll strip casting process, the casting speed has a significant influence on the metal flow and temperature distribution in the molten pool, which will affect the stability of this process and the quality of the produced products. Based on a 3D coupled thermal-flow analysis, a combination of the experimental results for twin-roll strip casting of stainless steel, heat equilibrium calculation and simulation results was conducted, and the boundary conditions of the heat exchange between the rolls
and molten pool has been treated effectively. The effect of the casting speed on the flow and temperature in the molten pool was given. Simulation result is in agreement with the measured value.
Length Effect on Formation of Metallic Patterns by Nanoimprinting Process – Molecular Dynamics Simulation
Authors: Cheng Ming Chieh , Hsueh Yun Liang , Chen Hsung Yu , Sung Cheng Kuo
Published: March 2009

The nanoimprinting process between a nickel mold and a gold thin film consisting of
9500 – 11000 atoms was studied using molecular dynamics computational simulation. The nickel mold and the gold thin film were both formed in face central cubical (FCC) single crystal, and the simulation condition was in an isothermal state of 300K. The Morse potential was utilized in order to determine interatomic forces and potentials. During the nanoimprinting process, jump-to-contact,
thin-film recovery, slip-line like, dead-metal zone and dislocation phenomena were observed. After finishing nanoimprinting processes, the interactive force curves between the mold pattern and thin film, and those inside the thin film were measured. By varying the pattern width of the mold and incorporating the measured force curves inside the thin film, the length effect on metallic pattern formation can be determined. In addition, through analytical investigation, it can be observed that the
thin-film thickness, the pattern width of the mold, and the applied force should be matched up very well in order to obtain good formation of metallic pattern.
Study on the Predictive Model for Shear Strength in Laser Welding Stainless Steel
Authors: Chien Wen T. , Chang S.W.
Published: March 2009

A predictive model is presented for the prediction of shear strength in laser welding
AISI304 stainless steel. Welding experiments conducted using a pulsed Nd:YAG laser machine while the laser welding parameters and their levels have been arranged according to design of experiments of Taguchi method. The tensile tests are performed after welding and the measurements of tensile strength are further calculated for shear strength. The data can be analyzed using the
principles of Taguchi method for determining the optimal laser welding parameters and for investigating the most significant laser welding parameter on shear strength. Furthermore, the results are treated as the training and recalling patterns for constructing a predictive model using back-propagation neuron network to predict shear strength for the range of laser welding operation tested. It is indicated that welding speed is the most significant affecting parameters on shear strength.
In addition, an increase in welding speed causes a decrease in shear strength is found. An average error 5.75％for shear strength can be found by comparing the experimental results obtained from conducting verification tests with the predicting values obtained from the established predictive model. It shows that the predictive model is capable of good predicting behavior of laser welding AISI304 stainless steel.
A Fast Auto-Focusing Method for Laser Diode Machine
Authors: Lee Kuang Chyi
Published: March 2009

This paper proposes a fast imaging auto-focus method to adjust the focus of laser diode products. The image of laser diode spot is processed to be a three-value image which is distinguished to be the background, blurred region and bright region. The ratio of areas between blurred and bright regions is used to judge whether the focusing is well-done. A four-point method is modified for this three-value image to get the areas of the blurred and bright regions. Thus, we can get the criterion for auto-focus. In the meantime, we can also get the offset of the laser diode from the center of laser diode spot. The four-point method is faster and more accurate than the area, three-point, contour-tracking and least-squares error methods of center-positioning. This auto-focus method of spatial domain is also faster than other methods of the energy strength in the frequency domain. Finally, we adjust the focus length of laser light by the servo control card and the AC servo motor, and then we can get the optimal focus length from the former image processing.
Fabrication of Rolling Mold for a 200μm Microlens Array by 3D LIGA-Like Processes
Authors: Tsai Jhy Cherng , Liu Ken , Yang Hsi Harng
Published: March 2009

This paper presents a series of three dimensional (3D) LIGA-like processes to fabricate microlens arrays on a cylindrical substrate. The processes consist of design of mask and rotating mechanism, coating of photoresist, 3D UV lithography, development and hardening, and electroforming. It transfers microlens array pattern to a φ76mm cylindrical stainless steel substrate intended for use as a rolling mold via electroforming. Process technologies are investigated and experiments are design and conducted as a proof of concept. Experimental results showed that
φ200μm microlens arrays can be fabricated on the substrate with good repeatability. The microlens pattern transferred to the 100μm-thick film showed the feasibility and stability of the 3D lithography process.
Three-Dimensional Micro-Flow Measurement in a Capillary with a Diode Laser Micro-Particle Image Velocitometry
Authors: Pan C.T. , Cheng P.J. , Hwang Yeong Maw , Chen M.F. , Chuang H.S. , Yang C.T.
Published: March 2009

A self-built micro-particle image velocimetry (micro-PIV) with a diode laser is established to measure the micro-fluidic phenomenon in a 100 μm rectangular capillary. By scanning method, a 3-D flow image with a flowrate of 0.3 μL/min is presented. With this calibration method, the measurement ability for 3-D micro-fluidic dynamics could be achieved. This technique also reveals its benefit and potential in metrology. Hence, it provides a helpful tool for Bio-MEMS research. The
experiment is proceeded under laminar flow, Re= 0.011. The measurement range is ranging from 0.05μm/s to 4.3mm/s. The vector grid resolution is optimized to 2.5 μm.
Development of a Non-Contact Tool Setting System for Precision Diamond Turning
Authors: Chao Choung Lii , Cheng T.A. , Lou D.C. , Chao Chung Woei
Published: March 2009

Precise and efficient tool setting technique and accurate tool shape monitoring are of
essential importance in ultra-precision diamond turning operation. The traditional way of tool setting are typically laborious, inefficient and rely heavily on experience. A big part of the tool setting is done by using a contact probe such as LVDT. The contact tool setting station can normally, depending on the resolution of the probes, place the tool tip to within a 1~10μm positioning accuracy. However, it is
running the risk of damage the delicate tool tip and has the ambiguity introduced by contact point of tool and touch probe. The optical/non-contact way of setting the tool do have the advantage of not having to touch the tool, but its resolution is limited by the optical diffraction limit and the resolution of the CCD device used (mm/pixel). A non-contact precision tool setting system is developed and built in this study using edge-detection image processing and sub-pixel dividing techniques in
conjunction with CNC controller of the precision turning machine to improve the system presently available. Depending on the sampling distance of the images, the error band gets wider when the sampling step becomes larger. In the case of 0.1μm sampling distance the obtained error band was within ±0.1μm and the results showed that tools of different shapes namely round, half-round and sharp tool could all be positioned to within an error band of ±0.1μm by using the developed tool
setting system.
A Silicon Oxide Hard Coating Deposited on Flexible Substrate by TMS - PECVD System
Authors: Liu Day Shan , Liao Yu Ko , Wu Cheng Yang , Juang Fuh Shyang , Lee Ching Ting
Published: March 2009

A hard coating silicon oxide film was deposited on flexible substrates by a PECVD
system. Tertramethylsilane (TMS) and oxygen were employed as raw materials. Surface roughness and hardness of these films deposited under various TMS/O2 gas flow ratio, rf power and chamber pressure were investigated. At adequate fabricated conditions, the original surface roughness of PMMA (~ 3.36 nm) and PC (~ 1.38 nm) substrates was markedly flatted to 1.52 and 0.39 nm,
respectively. Meanwhile, the surface hardness of coated PMMA and PC substrates was also enhanced to 6.077 GPa and 3.978 GPa, respectively. The hardness of silicon oxide film deposited by TMS-PECVD system was superior to silicon oxide films prepared from e-beam evaporation and dipping technologies.
Development of Real Time Monitoring System Using Controller Area Network
Authors: Huang Rong Wen , Huang Hsian Wei
Published: March 2009

This paper presents a new development of a real time monitoring subsystem in a
general-purpose real time monitoring and diagnosing system using controller area network (CAN) technology. To validate the designed concept, several vehicle electric utility devices are constructed as CAN nodes and are integrated into the CAN bus. An intelligent transducer to convert utility current and voltage is designed and fabricated with micro-controllers. An automatic node detection
mechanism is also developed and added to detect the newly jointed/retrieved nodes and record the running history for further diagnosis when system or device malfunction happens. The system design configuration, implementation and verification are demonstrated with actual test data, and the test results demonstrate that the proposed system accomplishes real time electric power monitoring with diagnosis capability.
Automatic Polishing of Super Accuracy Mirror Mold with Free-Form Surface by Curvature Analysis
Authors: Tsai Ming June , Fang Jing Jing , Huang Jian Feng
Published: March 2009

This paper proposed a polishing path planning method of super accuracy mirror mold with free-form surface by curvature analysis. First, IGES files of free-form surfaces are read and the mold geometry is regenerated as B-spline surface by the Automatic Mold Polishing System (AMPS). By using the derivative properties of B-spline surface, normal vector and principal curvatures at any point of the surface are calculated. In addition, the effective contact width between polishing tool and mold surface based on the grain size and the principal radii of curvature is also determined. The minimum contact width in 3-D is mapped onto the (u, v) parameters of B-spline surface. Then a modified Peano fractal path with weaving function is calculated based on the effective contact width in the (u, v) coordinate. This Peano-weaving path was tested on an optical mold with free-form surface. The polishing result shows the method is very effective and achieves the level of mirror surface with roughness Ra 29nm.
Skew Ray Tracing and Sensitivity Analysis of Paraboloidal Optical Boundary Surfaces
Authors: Sung Chi Kuen , Lin Psang Dain
Published: March 2009

One of the most popular mathematical tools in fields of robotics, mechanisms and
computer graphics is the 4x4 homogeneous transformation matrix. In previous work we applied this matrix to the optical domains of flat and spherical surfaces for: (1) skew ray tracing to determine the paths of skew rays being reflected/refracted; (2) sensitivity analysis to determine by direct mathematical analysis the differential change of incident point and reflected/refracted vector with
respect to change in incident light source. The present work extends our previous work to include the case of parabaloidal boundary surfaces.
Development of an Intelligent Virtual Reality System for High Speed Machining
Authors: Sheu Jinn Jong , Fu T.C.
Published: March 2009

An intelligent E-Manufacturing system was developed in this paper. The high speed
machining center was rebuilt using 3D CAD system. The moving table (X axis), span column (Y axis), spindle (Z axis) and the tool changing system were modeled precisely. The high speed cutting (HSC) experiments of AL 6061 were carried to obtain the cutting forces and surface roughness for different cutting conditions. The backward propagation supervised artificial neural network (ANN)
system was developed to predict the results of the high speed cutting. The intelligent virtual reality (VR) system of high speed cutting was developed integration the ANN and the VR environment. The users were able to learn the manual and the CNC operations of the HSC machine. The actions of users
were recorded and evaluated to judge the learning results. The cutting results of forces and surface roughness of user’s NC program was predicted by the ANN system to assist the NC programmer to adopt the suitable cutting parameters. The developed VR system was deployed to the internet webpage to supply a good E-Learning and E-Manufacturing environment.
Synthesis of Au Nanoparticles@Mesoporous Silica Templated by Neutral Block Copolymers: Application in CO Oxidation
Authors: Yeh Yi Qi , Yen Chun Wan , Lin Hong-Ping , Lin Yu Cheng , Chang Tsung Chain
Published: March 2009

A citrate-stabilizing Au nanoparticles aqueous solution was prepared at near 0 oC by
reducing tetracholoaurate(III) ions with sodium borohydride. Combining with Pluronic block copolymers, the citrate-stabilizing Au nanoparticles was nearly completely embedded in the mesoporous silica channels via fast silicification with silicate solution at near neutral pH. After calcination for removing organic templates, Au nanoparticles@mesoporous silicas of high surface area and pore volume were obtained. With different block copolymer, the pore size of the mesoporous silica can be tuned. The Au nanoparticles@SBA-15 mesoporous silica exhibits high
catalytic activity to CO oxidation reaction.
Fatigue Life Prolongation of Carburized Steel by Means of Shot-Peening
Authors: Haga Shigeyoshi , Harada Yasunori , Tsubakino Harushige
Published: March 2009

In this study, we’ve used carburized-quenched-tempered steels that received shot-peening process with different shot grain sizes and evaluated variation of surface property of the steels. As a result of study, it is demonstrated that the fatigue life of carburized steels can be prolonged significantly by increasing surface hardness and compressive residual stress and by reducing surface roughness and abnormal carburized case depth at superficial layer, which we’ve investigated in the study.
Laser Cutting Quality of the Ceramic Slabs
Authors: Wang Xu Yue , Xu Wen Ji , Kang Ren Ke , Liang Yi De
Published: March 2009

An experimental analysis is presented which investigates the relationship between cutting parameters and the volume of material removal as well as its cutting quality on a Nd:YAG laser cutting system. The parameters that varied on two testing thickness during cutting include cutting speed, incident laser power and focal position in a continuous through cut. Various trends of the kerf geometrical features in terms of the varying process parameters are analyzed and shown to be reasonable. Discussions are also given on kerf geometry control in situations with cutting parameters. It shows that the effects of varying parameters such as cutting speed, laser power and focal position on cutting kerf width, surface roughness, and striation that have provided a deeper understanding of the laser machining.
Simulation and Analysis for Layout of Aerospace Sheet Metal Process with Lean Concept
Authors: Huang Chi Kong , Chang Hsien Ming , Lin Chia Hui
Published: March 2009

Aerospace industry is a value-added and technology integrated industry. Sheet metal parts are important portion of aerostructures. The sheet metal production line combines five different routing types together. This study tries to make a comparison between job shop layout and cellular layout with lean concept. According to precedence diagram of sheet metal fabrication process, the
model and measurement indicators can be constructed. The simulation software SIMPROCESS is then used to simulate the real-world cases under dynamic conditions. After the verification and validation process, we analyze the results that collected by simulation and provide the suggestions for the layout of aerospace sheet metal process.
Reliability Study of Cutting Tool Based on the Reliability-Dependent Hazard Rate Function
Authors: Lin Wei Shin
Published: March 2009

In this study, the reliability-dependent hazard rate function is used to describe the reliability of the cutting tools. The reliability equation has been evaluated via normalization treatment. The reliability function of the cutting tool under different cutting speed can be obtained respectively by using this reliability equation. The experimental results proved that the reliability equation evaluated from this
study is accurate and feasible.
A Deterministic Model for a Manufacture System with an Advance Purchase Discount
Authors: You Peng Sheng , Su Chung Ming
Published: March 2009

Most production planning models assume that the backorder or advance purchase price is the same as the regular purchase price. In practice, since most advance purchase customers may expect to purchase items at discount prices, the purchasing behavior of these customers may differ from the regular purchase customers. In the present paper, we developed a production planning model
for dealing with a manufacturing system with an advance purchase discount. The objective of the paper is to maximize the unit time profit by jointly determining the advance purchase discount rate and the size of a production run.
Geometric Design of the Pinion with Two Circularly Arrayed Cylindrical Teeth for Roller Drives
Authors: Lai Ta Shi
Published: March 2009

This paper presents geometric design procedures for a new type of roller drive. Here, the pinion has two circularly arrayed cylindrical teeth instead of one circularly arrayed. This proposal is based on coordinate transformation and envelope theory, from which the epicycloid profiles are obtained. The centers of the cylindrical teeth of the pinion are determined by equidistant offset a distance 3 ρ (pinion-tooth radius). The real pinion profiles are the equidistant curve of the epicycloid
profiles. Two examples are presented to demonstrate that this approach is feasible.
Constraint-Based Multidisciplinary Collaborative Design Method of Gear Drive
Authors: Chen Liang , Gao Cheng Hui , Jin Guo Dong
Published: March 2009

The essence of the multidisciplinary collaborative design problem (MCDP) is the
coordination of the design variables among multiple disciplines on the basis of the all constraints of all disciplines. There exist some problems such as the early detection of design conflicts and the determination of the consistency domains of the design variables, etc. The resolving of these problems can help designers avoid bad decision-making, reduce the design iteration and improve the
design efficiency. Aiming at the problems, this paper proposes a constraint-net model to describe and manage all the design variables and constrains of all disciplines, discusses the reformulating method of the MCDP to improve computation efficiency, and develops the interval propagation algorithm to
determine the consistency domains of the design variables, etc. A gear drive is taken as an example to illustrate the effectiveness of the proposed method.
A Theoretical and Experimental Study on Precision Controlling of Generated Path of an Elastic Linkage
Authors: Liu Jian Qin , Zhang Ce
Published: March 2009

In this paper, generated path control of an elastic linkage is first controlled using a five-bar linkage with a variable length crank. The theoretical foundation of precision control of generated path of elastic linkage is formed by application of an optimal method. Experimental study of the generated path of linkages is made on the basis of the theoretical study. The experimental results agree with the
theoretical one essentially and prove the feasibility of the theory.
A Kalman Filter-Based Automatic Rotor Dynamic Balancing Scheme for Electric Motor Mass Production
Authors: Tseng Chyuan Yow , Shih Ting-Wei , Lin Jun-Tsun
Published: March 2009

When manufacturing electric motors, the armature must be carefully balanced before the motor is assembled to ensure that the motor remains within specified vibration limits when in operation. This study develops a novel scheme for the automatic balancing of motor armatures. In the proposed scheme, a Kalman filter is employed to make the milling system adaptive to the wear conditions. The balancing scheme is validated by performing a series of experiments using automobile starting motor armatures.
Modeling of Unidirectional Growth in a Single Crystal Turbine Blade Casting
Authors: Xu Qing Yan , Liu Bai Cheng , Liang Zuo Jian , Li Jia Rong , Liu Shi Zhong , Yuan Ha Llong
Published: March 2009

Single crystal superalloy turbine blade are widely used in aero-engineering. However, there are often grain defects occurring during the fabrication of blade by casting. It is important to study the formation of microstructure related defects in turbine blades. Single crystal blade sample castings of a nickel-base superalloy were produced at different withdrawal rates by the directional solidification process and investment casting. There was a difference between the microstructure morphology at the top part of the turbine blade sample castings and the one at the bottom. Higher withdrawal rates led to more differences in the microstructure and a higher probability of crystallographic defect formation such as high angle boundaries at locations with an abrupt change of the transversal section area. To further investigate the formation of grain defects, a numerical simulation technique was used to predict the crystallographic defects occurring during directional solidification. The simulation results agreed with the experimental ones.
Back Diffusion of Manganese during Solidification of Carbon Steels
Authors: Turkeli Altan , Kirkwood David H.
Published: March 2009

In this study, back diffusion of manganese in solid between secondary arms in the ternary Fe – 1.6 wt % Mn – 0.1, 0.21, 0.4 and 0.75 wt % C alloys was investigated in unidirectionally solidified quenched specimens which solidified in the range of 0.25 K/s to 4.15 K/s cooling rates. Manganese back diffusion in the solid phase during the growth has a large influence on microsegregation when the first solid formed is delta-ferrite. A decrease in Cmin after 0.1 wt % C has been observed because the fraction of delta phase decreases with increasing carbon content. Only a small rise during the growth was found in both 0.4 and 0.8 wt % C steels but there was no difference between them indicating that both solidify as austenite. Secondary dendrite arms grown at the lowest cooling rate (around 0.3 K/s) always disappeared at the end of solidification for all steels. These high increases in Cmin were attributed to the high coarsening, back diffusion and TGZM processes. The Cmin calculations obtained from the secondary dendrite arm coarsening model are in a good agreement with the experimental measurements.
Investigation on the Morphological Instability during Directional Solidification of a Transparent Alloy during Sounding Rocket Flights
Authors: Weiß A. , Sturz Laszlo , Zimmermann Gerhard
Published: March 2009

The movement and morphological change of a solid-liquid interface in directional solidification was investigated during two sounding rocket flights. By using the transparent binary alloy Succinonitrile-Acetone the dynamic processes at the solidification front could be observed directly. Both the planar interface growth, the onset of instability and the characteristic features of the interface morphology, i.e. the evolution of the primary spacing and amplitudes of the cells and dendrites were evaluated. The comparison with a calculation of the morphological instability based on the theoretical model of Warren and Langer showed a good agreement concerning the critical time and velocity of the solidification front.
Eutectic Solidification of Ternary Al-Cu-Ag Alloys: Coupled Growth of α(Al) and Al2Cu in Univariant Reaction
Authors: Hecht U. , Witusiewicz Victor T. , Drevermann A. , Böttger B. , Rex S.
Published: March 2009

Coupled, regular eutectic growth of α(Al) and Al2Cu from ternary Al-Cu-Ag liquid
alloys is investigated with focus on the formation and the characteristics of eutectic cells in unidirectionally solidified, polycrystalline, bulk samples. The topologic anisotropy of the lamellar eutectic leads to destabilization along the lamellae with elongated cells being intermediate to stable cells, irrespective of the crystallographic orientation of the phases. The formation of stable cellular patterns with elongated or regular cell structure is explained with reference to the crystal orientation
of the phases α(Al) and Al2Cu, measured by electron backscatter diffraction (EBSD).
Solidification of Hypereutectic Thin Wall Ductile Cast Iron
Authors: Pedersen Karl Martin , Tiedje Niels
Published: March 2009

Hypereutectic ductile iron was cast in green sand moulds with four plates with thickness of 1.5, 2, 3 and 4 mm in each mould. Temperatures were measured in the 3 and 4 mm plate. The temperature curves showed that eutectic solidification was divided into two stages: primary and secondary eutectic solidification. The first stage, which was relatively short, had none or very little recalescence. Further under cooling, followed by reheating during recalescence, was necessary to
initiate the second part of the eutectic solidification. Both the secondary under cooling and recalescence was larger in the 3 mm plates than in the 4 mm plates. All 1.5 mm plates contained carbides but the other plates solidified without carbides. Metallographic examination showed two populations of graphite nodules. A small group of nodules was larger than rest of the nodules. Color etching revealing the segregation of Si showed a higher Si content in the ferrite around the larger
nodules compared to the ferrite around the rest of the nodules. This indicates that solidification took place along the following path: The solidification starts with nucleation and growth of primary graphite nodules. This probably starts during the filling of the mould. The primary nodules act as nuclei for austenite. As austenite easily nucleates on graphite the temperature will be the same for the 3 and 4 mm plate for the first part of the eutectic solidification. This first part of the
solidification ends when concentration of carbon around austenite dendrites is too large and new nodules have to nucleate and grow. The larger under cooling for the 3 mm plates compared to the 4 mm indicates that the nucleation of new nodules is governed by kinetics even in very well inoculated melts.
Newton Thermal Analysis of Gray and Nodular Eutectic Cast Iron
Authors: Chavez M.R. , Amaro A. , Flores C. , Juarez A. , González-Rivera Carlos
Published: March 2009

The purpose of this work is to analyze the capability of Newton Thermal Analysis (NTA) to detect differences of the solidification kinetics between eutectic gray and ductile irons obtained from the same base alloy. The NTA experimental output has been analyzed with a simple micromacro modeling approach. The outcome of this work suggests that NTA has a good potential as a qualitative tool to characterize the solidification kinetics of alloys.
Preparation of Size Controlled Nanometric Spheres of Colloidal Silica for Synthetic Opal Manufacture
Authors: Cortés Escobedo C.A. , Muñoz-Saldaña J. , Jaramillo-Vigueras D. , Espinoza-Beltrán F.J.
Published: March 2009

In this work, we present a modification of the sol-gel based, Stöber, Fink and Bohn’s (SBF) procedure for the preparation of nanometric spheres of silica with a monomodal distribution of size and controlled diameter. In the SBF method, tetraethyl orthosilicate (TEOS) is used as a precursor molecule and hydrolysis and condensation reactions to form chains and branches of Si-O bonds are carried out. The novelty of this work consists in the use of an aqueous ammonium hydroxide solution as ammonia source. Graphics of particle size as a function of reagent contents are presented (reaction yield control) and differences to the results from the original SBF method are discussed. This procedure is the very first step for the development of a sol-gel synthetic opals preparation process. As a result, the best route to prepare monodisperse spheres in the whole range of 250 to 850 nm is that of keeping constant the TEOS and NH3 contents at 0.28:1M varying water contents in the range of 8 – 12.5 M.
Determination of the Work Hardening Exponent by the Hollomon and Differential Crussard-Jaoul Analyses of Cold Drawn Ferrite-Pearlite Steels
Authors: Mejía I. , Maldonado C. , Benito Josep Antonio , Jorba Jordi , Roca Antoni
Published: March 2009

This research work analyses the effect of cold working level produced by drawing, on the work hardening exponent of 0.18 and 0.43 % C ferrite-pearlite steels. Such analysis is carried out by means of true stress-true strain curves derived from uniaxial tension tests. The work hardening exponent behaviour was determined by using Hollomon and differential Crussard-Jaoul models. It is found that the work hardening exponent decreases as a function of the applied cold-drawing level,
and negative values were obtained when differential analysis is used. The results indicate that the Hollomon analysis shows some deviations from the experimentally determined true stress - true strain curves while the differential Crussard-Jaoul analysis fits better when two work hardening exponents are considered. This analysis establishes two exponents for different stages of plastic
deformation which are determined by the sharp slope change in the plot of ln (d σ/d ε) - ln ε.
A Tetragonal Phase in Cr(N,O) Thin Film Prepared by Pulsed Laser Deposition
Authors: Inoue Jun , Nakayama Tadachika , Suzuki Tsuneo , Suematsu Hisayuki , Jiang Wei Hua , Niihara Koichi
Published: March 2009

Chromium oxynitride (Cr(N,O)) thin film have been successfully prepared by using pulsed laser deposition. The composition of the thin film was determined to be Cr0.50N0.23O0.28 by Ruthreford backscattering spectroscopy (RBS). The structural analysis was carried out by using X-ray diffraction (XRD), and out-of-plane and in-plane measurements were used to clarify the axial ratio (c/a) of the Cr(N,O) phase. The lattice constants of a and c axes in the Cr(N,O) phase were found to be 0.414 and 0.419 nm, respectively. From these results, the cubic to tetragonal phase change by substitution of the oxygen atoms for nitrogen atoms was confirmed for the crystal Cr(N,O) compounds.
Clarification of Wire Heating Process in Pulsed Wire Discharge with High-Speed Gas Puff
Authors: Tokoi Y. , Nakayama Tadachika , Suematsu Hisayuki , Jiang Wei Hua , Yatsui K. , Niihara Koichi
Published: March 2009

Copper nanosized powders were prepared by pulsed wire discharge (PWD) in N2 gas at low pressure (130 Pa) with high-speed gas puff. The pressure around one of the electrodes was changed to investigate the effect of electrical discharge prevention by gas puff. The peak pressure was changed from 22 kPa to 10 kPa in the gas puff apparatus by changing the distance from an acrylic resin tube and a bottom plate. The energy deposition in the copper wire at 22, 15 and 10 kPa was about 40, 37 and 33 J, respectively. The energy deposition in the wire increased with the increase in pressure around the electrode.
Preparation of Ternary Compound BaLi2Ti6O14 by the Sol-Gel Process
Authors: Garza-Tovar Lorena L. , Torres-Martínez Leticia M.
Published: March 2009

Ceramic compound with the formula BaLi2Ti6O14 was prepared by sol-gel method at
basic conditions, using ammonium hydroxide as hydrolysis catalyst. Some portions of gel sample obtained were heat treated at 200, 400, 600, and 800°C. Samples were characterized by X-ray diffraction (XRD), thermal analysis (DTA-TGA), UV-Vis and FTIR. Crystalline phase was formed when a sample was treated at 800°C for 6h. This material has been previously synthesized by solid state reaction using temperatures as high as 900-1150°C for 2 to 10 days. The crystal structure of
BaLi2Ti6O14 is similar to that corresponding strontium containing phase, SrLi2Ti6O14, which has been reported as catalyst for oxidative dehydrogenation of lower alkanes.
Factors of Nozzle Design Affecting on Supersonic Flow in Cold Spray Process
Authors: Jang Sung Hwan , Park Sung Han , Han Jeong Whan , Lee Chang Hee , Kim Hyung Jun
Published: March 2009

The cold spray process is a relatively new process using high velocity metallic particles for surface modifications. Metallic powder particles which are injected into a converging-diverging nozzle are accelerated to supersonic velocities. In this study effects of nozzle design such as diameter of nozzle throat and length of converging and diverging part of the nozzle on gas and particle velocities developed after the nozzle exit are investigated.
Effect of the Palladium Mid-Layer on the Cyclic Oxidation of Platinum Aluminide Bond Coating
Authors: Hong Seok Jun , Choi Jae Woong , Hwang Gil Ho , Han Won Kyu , Park Joon Shik , Kang Sung Goon
Published: March 2009

Platinum/Palladium modified aluminide coatings prepared by aluminide pack
cementation on the nickel base superalloy Inconnel 738. The platinum/palladium modified aluminide coating of cyclic oxidation behavior at 1200°C was investigated by TGA, XRD and SEM/EDS. Platinum/Palladium modified aluminide coatings showed better cyclic oxidation resistance than Platinum modified aluminide coating and palladium modified aluminide coating compared. Pt and Pd alloy played an enough role in alumina stabilization and in delaying the degradation of β-phase.
Materials for Devices Applications in Life Sciences
Authors: Li G.P. , Bachman Mark
Published: March 2009

The unprecedented technology advancements in miniaturizing integrated circuits, and the resulting plethora of sophisticated, low cost electronic devices demonstrate the impact that micro/nano scale engineering can have when applied only to the area of electrical and computer engineering. Current research efforts in micro/nano fabrication technology for implementing integrated devices hope to yield similar revolutions in life science fields. The integrated life chip technology requires the integration of multiple materials, phenomena, technologies, and functions
at micro/nano scales. By cross linking the individual engineering fields through micro/nano technology, various miniaturized life chips have been developed at UCI that will have future impacts in the application markets such as medicine and healthcare.
Graphite/Carbon Nanofiber Composite Anode Modified with Nano Size Metal Particles for Lithium Ion Battery
Authors: Jin Wen Jie , Kim Taek Rae , Moon Seung Hwan , Lim Yun Soo , Kim Myung Soo
Published: March 2009

Carbon nanofibers and nano-size metal particles were incorporated into the surface of graphite particles. The carbon nanofibers prepared from the decomposition of ethylene over nickelcopper catalyst and the micro-size silicon particles were directly introduced into the graphite particles by mixing. Nano-size tin particles were also incorporated into the graphite particles by impregnation. The three different graphite composites were tested as anode base materials for lithium ion secondary battery. The incorporation of a certain amount of carbon nanofibers into the
graphite electrode improved the cyclic performance as well as the initial charge/discharge capacity. With the introduction of silicon, the initial charge/discharge capacity increased but exhibited the bad
cyclic characteristics. With the modification with tin, an improved electrochemical performance was observed in both initial charge/discharge capacity and cyclic characteristics.
Effects of Multiwalled Carbon Nanotubes on the Cycle Performance of Sulfur Electrode for Li/S Secondary Battery
Authors: Jeong Sang Sik , Choi Young Jin , Kim Ki Won
Published: March 2009

Lithium sulfur cells were prepared by composing with sulfur cathode, 0.5M LiCF3SO3 in tetra ethylene glycol dimethyl ether (TEGDME) solution and lithium anode. Multiwalled carbon nanotubes (MWNTs) were used to form the high electric network and prevent the dissolution of lithium polysulfides in sulfur cathode. The effects of additive contents were investigated by discharge
test. The morphology of cathode with MWNTs (20wt.%) has rough and submicro porous. The initial discharge capacity of lithium sulfur cell using multiwalled carbon nanotubes (MWNTs) was 1,200mAh/g-sulfur, which was better than those of acetylene black (AB). The cycle performance of lithium sulfur cell was remarkably improved by the the addition of MWNTs.
Thermoelectric Properties of Te Doped CoSb3 -4mol%Zn4 Sb3
Authors: Jang K.W. , Kim Il Ho , Lee J.I. , Choi G.S.
Published: March 2009

Te doping effect on the thermoelectric properties of solid solution was investigated. 2at% Te doping was found to be most effective to improve the dimensionless figure of merit, ZT, of pseudo-binary CoSb3-4mol%Zn4Sb3. Maximum ZT of 0.69 was obtained at 450K in CoSb3- 4mol%Zn4Sb3 doped with 2at% Te. Heavy doping of Te above 3at% caused thermal conductivity to increase very high because of the formation of metallic CoSb2 phases and thus did not improve ZT.
Synthesis and Analysis of Nano-Crystalline LiNiVO4
Authors: Thongtem Titipun , Kaowphong Sulawan , Thongtem Somchai
Published: March 2009

LiNiVO4 was synthesized using Li2CO3, NH4VO3 and Ni(CH3COO)2.4H2O as starting reagents and citric acid as a chelating agent. Mole ratios of metals to citric acid used for the preparation were 1 : 1 - 1 : 4. Carboxylate precursors were calcined at high temperatures to form powder. TGA data showed weight loss due to the evaporation and decomposition processes. FTIR showed the stretching
bands of VO4 tetrahedron at 642, 713 and 813 cm-1. For 1 : 3 and 1 : 4 mole ratios, nano-crystals of inverse spinel LiNiVO4 (produced at 450 oC calcination for 6 h) were detected by XRD, electron diffraction, SEM and TEM.
Photocatalytic Properties of TiO2 Coatings Prepared by Cold Spray Process
Authors: Han Jong Hyuck , Lee Soo Wohn , Lee Eun Ah , Xiong Tian Ying , Bao Zebin , Du Hao
Published: March 2009

Cold spray process offers an oxidation-free atmosphere. It is usually used for TiO2
coatings used in photocatalytic applications to purify a given medium. Cold sprayed coatings with spray dried powder and evaporated powder were compared. Investigation of properties using SEM, XRD, roughness test were performed. SEM and XRD data were found to be very similar, however, variations were found for the surface roughness. Nano-sized powders were used in this investigation,
therefore the coatings achieved were very thin in comparison to those from conventional powders, also they showed high uniformity.benzene removal from air by means of photoelectrocatalytic reaction was achived.
A Simple Reliable Method of Selecting Epoxy Molding Compounds for High Power Short Wavelength Light Emitting Diode Packages
Authors: Lee Chong Mu , Kang Seung Mo , Yim Keun Bin , Kim Sook Joo , Kim Hyoun Woo
Published: March 2009

Epoxy molding compounds (EMC) with higher thermal stabilities are urgently needed as the light emitting diode (LED) becomes brighter and the wavelength of the its light becomes shorter. This paper proposes a simple reliable method of evaluating the thermal stabilities of commercial EMCs. The transmittances of most commercial EMC samples for high power short wavelength LED packages were decreased by heat treatment at 150oC for 200hr. Also the thermal stabilities of
the samples were confirmed by measuring the weight losses through TGA. The experimental results suggest that employing a good heatsink is indispensable in highly bright short wavelength LED packages.
CdSe/ZnS Quantum Dots Loaded Solid Lipid Nanoparticles: Novel Luminescent Nanocomposite Particles
Authors: Liu W. , Liang J.G. , Zhu Y.L. , Xu H.B. , He Z.K. , Yang X.L.
Published: March 2009

Highly luminescent lipophilic CdSe/ZnS core-shell QDs with an emission maximum at
556 nm were synthesized. These QDs were successfully encapsulated into solid lipid nanoparticles (SLNs) using the thin-layer ultrasonication technique. Transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and zeta potential measurement were employed to characterize the QDs-loaded SLNs for morphology, particle size with polydispersity index (PI), and
zeta potential. The nanocomposite particles obtained appeared in a shape of spherical or near spherical with the average size of 92.3 nm, PI of 0.235 and zeta potential of -28.74 mV. Each nanocomposite particle contains tens of QDs observed by TEM. Fluorescence measurements show that the encapsulated QDs maintain their high luminescence and narrow/symmetric emission spectra. The experiment result indicates that the nanocomposite particles are stable and slow to
photobleach. These luminescent nanocomposite particles have good potentials in biological imaging applications.
Enhancement of the Characteristics of the ALD HfO2 Film by Using the High-Pressure D2 Annealing
Authors: Baik K.H. , Ahn Seung Joon , Park Chul Geun , Lee Seung Young , Ahn Seung Joon
Published: March 2009

We investigated the characteristics of the HfO2 layer deposited by ALD method in
MOSFET devices where the HfO2 film is incorporated as the gate dielectric layer. The HfO2 film was annealed with forming gas (FG) or high-pressure D2 gas to investigate the effect of annealing on the characteristics of the MOSFET device. It was found that the drain current and transconductance of the D2-annealed MOSFET device increased remarkably by ~10% compared with those of
FG-annealed MOSFET device, which is a definite improvement that may contribute to reliable operation of the ultra high-density MOSFET devices.
Effect of Heat Treatment on Microstructure, Tensile Properties and Damping Capacity of Mg-Zr Wrought Alloy
Authors: Jun Joong Hwan , Lee Geon Ha , Kim Jeong Min , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Microstructures, tensile properties, and damping capacity of the hot-rolled and annealed K1A (Mg-0.7%Zr) wrought alloy were investigated in comparison with those of a commercial AZ31 (Mg-3%Al-1%Zn-0.2%Mn) wrought alloy. The K1A alloy in hot-rolled state shows 116 and 183MPa of tensile yield strength (σYS) and ultimate tensile strength (σUTS), respectively, which are significantly
higher than those (40 and 130MPa) of the K1A casting alloy. The hot-rolled K1A alloy exhibits 10.4% of specific damping index (SDI) and subsequent annealing treatment remarkably enhances its SDI up to 19.7% without sacrificing the tensile strength. Although the annealed AZ31 alloy has 3.9% of low SDI,
its tensile properties are still higher than those of the K1A alloy.
Microstructures and Mechanical Properties of Mg-Zn-RE-Ca Casting Alloys
Authors: Jun Joong Hwan , Park Bong Koo , Kim Jeong Min , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Influences of Ca addition on microstructures and mechanical properties at room and elevated temperatures up to 300oC were investigated for ZE41 (Mg-4%Zn-1%Zn)-(0~1.0)%Ca permanent mould casting alloys, based on the results from X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and tensile tests. The
microstructure of ZE41 alloy is characterized by dendritic α-(Mg) grains surrounded by Mg7Zn3-based eutectic network phase. The average size of α grains decreases continuously with an increase in Ca
content. The Ca-containing ZE41 alloys have Mg7Zn3-(RE)-(Ca) eutectic phase, in which Ca is distributed inhomogeneously owing to its strong segregation power. It is noteworthy that tensile yield strength (YS) for the ZE41 alloy was enhanced with increasing Ca content at all temperatures up to
300oC, which demonstrates that Ca can play a beneficial role in improving its tensile strength at room and elevated temperatures. The ZE41 alloy with 0.5%Ca showed the highest ultimate tensile strength (UTS) at room temperature, but in the range of 175 to 300oC, the higher the Ca content, the greater the
UTS. The improved tensile strength of the Ca-containing ZE41 alloy would be caused by the refined α grains and higher thermal stability of the Mg7Zn3-(RE)-(Ca) eutectic phase.
VOC Decomposition by Photocatalytic Wall Paper
Authors: Taoda Hiroshi , Fukaya Mitsuharu , Watanabe Eiji , Tanaka Kazuhiko
Published: March 2009

Sick house syndrome caused by volatile organic compound (VOC) in the room is a serious problem in Japan. A photocatalytic wall paper was developed which is a wall paper coated with a visible light type of photocatalyst. When irradiated by light, the photocatalyst generates strong oxidative potential and decomposes almost all organic substances to water, carbon dioxide, and others. As a result of our experiment using the photocatalytic wall paper, toluene and acetaldehyde were decomposed efficiently even under a fluorescent lamp, and the photocatalytic wall paper had also strong anti-bacterial effect under the fluorescent lamp.
Microstructure Analyses and FE Simulation of Automotive Product in the Hot Forging Process Using Aluminum Alloys
Authors: Lim Seong Joo , Lee Geun An , Jeong Ha Guk , Choi Seo Gou , Lee C.H.
Published: March 2009

In automotive industries, components have replaced steel with aluminum alloys since the automotive parts that used aluminum alloys have the ability to improve the environment by lower weights and recycling of waste materials. In this study, experiments were carried out to investigate the characteristics of the developed aluminum alloys according to the forming temperature and speed.
The microstructure of forged product in hot forging process was also investigate. The results revealed that the grain size of aluminum alloys was grown according to the forming temperature and speed. Three-dimensional finite element analyses were also carried out to investigate the forming load, deformed shape, and the stress distribution of the workpiece in the hot forging process. The deformed shape of the workpiece was consistent with the trend of experimental results.