bluuebunny/crossref_metadata_2025 huggingface dataset:
Sliding Mode Path Tracking Control for Spraying Mobile Robots Based on Weighed Integral Gain Reaching Law
Authors: Niu Xue Mei , Gao Guo Qin , Zhou Hai Yan
Published: March 2013

For the spraying mobile robot, in order to solve the bad effect of the complex unstructured environment of intensive planting, ground obstacles and spatial disorders coexisting on the path tracking control precision, a sliding mode control method is proposed based on weighted integral gain reaching law to reduce chattering and to improve tracking performance of the system. Moreover, the asymptotical stability of the closed loop system is proved using Lyapunov function. Finally simulation results illustrate the validity and feasibility of the proposed control method.
Tensile and Compressive Creep Behavior of Magnesium Alloy AZ91D
Authors: Sujatanond Supamard , Mutoh Yoshiharu , Miyashita Yukio , Otsuka Yuichi
Published: March 2013

Tensile and compressive creep tests of the extruded magnesium alloy AZ91D were carried out in vacuum at 150°C under constant engineering stresses ranged from 60 to 150 MPa. From the test results, the secondary creep rate in tension was found to be significantly higher than that in compression. Moreover, the estimation method of creep curve under a constant true stress was proposed by considering the reduction of cross sectional area during tensile loading where the specimen cross-sectional area and length were measured periodically until the end of creep test. The creep curve under a constant true stress obtained in the present study was still different between tensile and compressive loadings. Therefore, it should be noted that the different creep curves and creep exponents should be used in the creep deformation analysis of structures.
Meshing Generation Platform for Industrial Production Models Based on 3D Computational Model
Authors: Wang Yun , Liu Su Xing
Published: March 2013

The meshing principles, coefficients and non-uniform meshing for 3D computational model was analyzed and a software platform was developed, containing both uniform and non-uniform meshing and visualization functions. Experiments for industrial production models demonstrated that: the developed platform can achieve good results for both uniform and non-uniform meshing. The implementation of the platform provides a good basis for developing more complete 3D modeling software.
The Application of Metal Materials in Exercise-Induced Bone Injury
Authors: Hou Jiang Yuan , Zhang Shao Qing , Ke Li
Published: March 2013

The bone injury induced by sports exercise and daily activities is more common, the metal materials were generally utilized in fixation and reconstruction of impaired bone, while the biomechanical properties of metal plate play a great effect on the stability of bone and blood supply of bone, which may produce important influence to rehabilitation efficacy. The biomedical metal materials obtain the widespread application in the clinical treatment of bone injuries after a long-term research and clinical screening. the effect of Material properties on Implant mechanics, Bone locking plate with ordinary steel mechanical properties, Material implantation on mechanical effect were analyzed in this study. The Clinical biomechanics properties and therapeutic effects of metallic material were influenced by their properties, forging process and clinical methods of implantation.
Research on Symbiotic Order of the Eco-Industrial Chain for Recycling Waste Materials Based on Input-Output Method
Authors: Li Ji Hong , He Xiao Min , Xiang Jing
Published: March 2013

The eco-industrial chain as an input and output of the ecosystem includes the economic and ecological inputs and outputs. The production processes between node enterprises stabilize the input-output structure of the eco-industrial chain through the linkage of material flow and energy flow. The analysis framework of input-output has built based on material flow. When the demand for the product changed, a new input-output matrix could be established. And then according to this matrix, relationships of material flow between node enterprises could be adjusted to realize the symbiotic order of the eco-industrial chain.
The Effects of Laser Shock Peening on the Heat Resistance Property of A356 Aluminum Alloy
Authors: Fan Bin , Fan Ji Wen
Published: March 2013

Laser shocking peening (LSP) is a good way to improving mechanical properties. The influence of laser shock peeening on the high temperature mechanical properties were studied by investigating the thermal stability of residual compressive stress induced by LSP and high temperature tensile properties. The samples treated by LSP were placed in annealing oven and insulated for 60mins under 200°C. The high temperature tensile tests were did on the MTS machine, the temperatures were 250°C. The results showed that the compressive residual stress induced by LSP were only released 19.7%, the residual compressive stress still remained at a high level, about-125.45MPa; the results from the high temperature tensile tests shows LSP can improved the elevated temperature tensile strength, the ultimate tensile strength（UTS） of LSP was from 319.79MPa to 252.63MPa，decreased 21%, but the UTS of untreated by LSP was from 283MPa to 130.18MPa，released 46.1%.
The Research of Information Extraction in Information System from SQL Server Based on System Table
Authors: Chen Huan Tong , Zheng Wei , Chen Yao Fei , Ni Ying Hua
Published: March 2013

This article describes the information extraction in information system from SQL Server. Through the system tables all information of SQL Server's internal objects in information system can be obtained, including databases, data tables, stored procedures and triggers and so on. Analysis the method of the object’s information extraction in information system. Describe the relationships of system tables in SQL Server through the graph and table in detail. A visual basic procedure using system table method is designed to achieve the table’s structure information for all user tables in specified SQL Server database. This method is more complete than the method based on ADOX.
Study on CT Image Reconstruction Applications in Industry
Authors: Zhang Rui Fang
Published: March 2013

We require high-precision measurement method in the modern industrial production. The method of measurement of industrial CT images is a good choice now. The face of some of the drawbacks of the current industrial CT images, this paper is starting from the study of industrial CT system structure and algorithm flowchart. We focus on the algorithm of Zernike moments, and on the basis of the algorithm itself, it carried out a number of improvements to improve the measurement accuracy of the industrial CT algorithm. Then design a set of industrial CT measurement method of intelligent software solutions, the specific design method and the structure model diagram will be given.
Mechanics Study on the Leaning-Type Arch Bridge during the Construction Process Based on Building Materials
Authors: Zeng Xin Cheng , Liu Ai Rong , Zhao Xin Sheng , Deng Jiang Dong
Published: March 2013

With the constructing project of Shengli Bridge as the background, this paper presents the measured stress and deformation data of main arch rib during the process of full framing scheme. The measured data are compared with the computation results.And the mechanical behaviors of the arch bridge were studied to reveal the changing tendency of stress and displacement of the main arch construction completed to completion stage. The analysis results show that the stress and the displacement of the key structures are in a reasonable range and meet the design requirements during the process of the construction process.
Analytical Solution of Sidewise Buckling of Two-Hinged Circular Arch under Concentrated Force
Authors: Kuang Ju Tao , Liu Ai Rong , Yu Qi Ca , Deng Jiang Dong
Published: March 2013

By the setting torsional and lateral displacement function of sidewise buckling of two-hinged circular arch under concentrated force, the single-arch structure's bending, torsional deformation and external force potential can be constructed. An analytical solution for the lateral critical buckling load of two-hinged arch is first deduced by using the energy method; the results are also compared and analyzed by the finite element method. The results show that the analytical solution of single arch’s lateral critical buckling load is in good agreement with the finite element numerical solution, and the validity of the formula is proven.
Research of Compensated AC Regulated Power Supply in Electric Power Systems Based on a High-Frequency Isolated Transformer
Authors: Zhang Qi Liang , Wang Ping , Yang Liu
Published: March 2013

In this paper, a new topology of compensated AC regulated power supply (ACRPS) in electric power systems based on a high-frequency isolated transformer (HFIT) is proposed. In order to overcome the slow response and low accuracy of the existing ACRPS, the phase shift regulating control (PSRC) based on instantaneous value of voltage single closed loop is applied as well as the software phase locked loop (SPLL). The proposed ACRPS has been simulated in the case of the voltage fluctuation, harmonics and frequency shift with Matlab. The simulation results show that output voltage precision is controlled within 0.5% and total harmonic distribution (THD) can be limited to less than 1%. In a word, the feasibility of the proposed ACRPS is effectively verified.
Study on Electromechanical Coupling Vibration of Simulation Technology Based on the Drive System
Authors: Wang Hong Ying
Published: March 2013

Study the mechanical and electrical system,according to the mechanical system of the coupling mechanics principle, the AC drive system is simplified as many degrees of freedom "spring - mass - damper" system,the quality of construction of three two-axis system,established the two shafts electromechanical coupling vibration mathematical model; Using the electromechanical coupling vibration simulation model, the parameters of the current regulator, damping, harmonic disturbances, gap and load disturbance of electromechanical coupling factors such as vibrations caused by dynamic process.Improve the dynamic performance of the system is significant, have the great value for the parameters of the system design and fault diagnosis on this study.
On-Line UHF Monitoring System of Partial Discharge for Electrical Equipment
Authors: Chen Guo Jin , Xu Ming , Liu Ting Ting , Ni Jing , Xie Dong , Zhang Yan Ping
Published: March 2013

The detection and fault identification of the partial discharge is the important aspect for the monitoring of the power equipment. For the lacks of the traditional detection methods, this paper analyzed the UHF signal characteristic parameters of the power equipment’s partial discharge, and developed the UHF detection system of the partial discharge. The A/D technology of the gain equalization and quantization in the different bands is studied, and the fault diagnosis strategy of the partial discharge based on the UHF and AE is proposed. On the premise to ensure the integrity of the partial discharge signals, the acquisition, amplification, analysis and storage of the partial discharge signal is realized. The case-based reasoning technology determines the fault type and fault degree of the partial discharge to make the accurate judgment for the operational state of the equipment and improve the intelligence level and the operational reliability for the state diagnosis of the power equipment.
Refractive Index Sensor of V-Shaped Fiber Microstructure Fabricated by Femtosecond Laser
Authors: Zheng L. , Sun X.Y. , Deng W.
Published: March 2013

The defect of fiber core or cladding near the core could result in imperfect total internal reflection (ATR) via multiple internal reflections along the fiber and attenuated light intensity of fiber. In this paper, V-shaped fiber microstructure was fabricated by femtosecond (fs) laser. The loss of light energy is sensitive to surrounding refractive index (RI), which is used to detect the refractive index of surrounding media. The depth of V-shaped microstructure is controlled by fabrication process, and it found that it has evident effect on RI sensitivity.
Thermal Design and Analysis of VOX Microbolometer
Authors: He Ji Xia , Jiang Jian Liang , Mehdi Aggoun
Published: March 2013

In this paper, we analyze the bridge legs in which the largest deformation can be observed by conducting simulation via ANSYS tools and determine the membrane layer structure, which consists of one 0.1μm thick VOX thermal sensing layer and 7 other layers with thickness ratio 0.1μmSi3N4/0.3μmSiO2/0.1μmSi3N4/0.05μmNiCr/0.1μmSi3N4/0.3μmSiO2/0.1μmSi3N4. The stable and transient thermal simulation analysis of the microbridge is performed. From the stable thermal analysis of temperature field profile, the highest and lowest temperatures and the temperature heterogeneity of the bridge deck are 300.526K, 300.468K and 0.058K respectively. The thermal time constant 6.0ms is acquired from the transient thermal analysis, which can reach the requirement of 60fps frame rate. Moreover the joule heating effect is then examined, which has influence on temperature rise of bridge deck with 3V voltage applied between two legs. The highest temperature of bridge deck is 300.354K which is lower than 300.526K caused by thermal radiation. At last, the force simulation analysis of microbridge is performed, which is based on the forementioned thermal analysis, the largest deformation is 46.45nm, the largest equivalent stress is 2.503GPa.
Study on Multilayer Electromagnetic Shielding Coating Fabrics Based on Graphite and Nickel
Authors: Chen Ying , Li Yuan Liang , Ma Xue Gang , Sang Rong Li
Published: March 2013

Nickel and graphite are selected as conductive powders. Water-based adhesive are selected as coating. Electromagnetic shielding textiles were prepared with coating method. In order to improve the shielding effectiveness of textiles, multilayer compositing is used. The surface resistivity, coating amount, electromagnetic shielding effectiveness are tested to select the best process.
Spray Deposited Thin Films of Tin-Doped Indium Oxide for Optoelectronic Applications
Authors: Malik Oleksandr , de la Hidalga-W F.J.
Published: March 2013

The structural, electrical, and optical properties of spray deposited tin-doped indium oxide (ITO) films are reported in this work. The films have excellent properties, as a transparent and conducting electrode, for applications in a wide range of areas of optoelectronics such as photodetection and photovoltaic. One example of the ITO thin films application in semiconductor-insulating-semiconductor (SIS) efficient solar cells and modules is shown.
Comparative Study on the Effective Dielectric Constant of the Graded Composites
Authors: Fan Chun Zhen , Wang Jun Qiao , Liang Er Jun
Published: March 2013

The effective dielectric constant of the graded composites was calculated with three different methods, namely, the nonlinear differential effective dipole approximation method (NDEDA), the Maxwell-Garnette method (MGT) and the sum rule method (Sum). In each layer of the graded composites, the distribution of the dielectric constant follows a Drude form. Our numerical results show that when the number of layers N inside the graded composites increases, a gradual transition from sharp peaks to an emerging broad continuous band is clearly obtained. Moreover, the results obtained by the MGT and sum rule methods achieve a good agreement with that by the NDEDA method when N is approaching infinity.
The Electrical Characteristics Induced by B+ Doping of Nanotube MOSFET
Authors: Wang Jie Yin , Xing Huai Zhong , Zeng Yi Jie
Published: March 2013

In this paper, we not only discuss the effect of doping concentration to conductivity but also some other factors. Such as the thickness of SiO2 and the resistance of the conductive part (Si shell). And we have got the consequence that the higher the doping concentration is, the higher conductivity. The reason is that doping increased carrier concentration and then increased µ. The thicker the Si shell is and the shorter lengths the nanotube has, the smaller resistance the conductive part has and the higher conductivity. About the thickness of SiO2, the situation is a little more complex. As a p-channel FET. When Vg>0, the thicker the SiO2 is, the higher conductivity. When Vg2 is, the higher conductivity. As a n-channel FET, the situation is opposite. The reason is about potential barrier height and the location of EF. At last we repeated the previous research work and have more optimization in a reasonable parameter range. The results demonstrate that we can control conductivity and reach high transport properties for core/shell nanocable MOSFETs by combination with multiple methods.
Study Swaging Process for Reduction Swage Effect in Hard Disk Drive
Authors: Bamrungwongtaree Joompondej , Mongkolwongrojn Mongkol
Published: March 2013

In hard disk drive manufacturing common uses ball swaging. It is a process that used to assemble a boss tower and an arm aperture. The swage ball has a larger diameter than an inner diameter of the boss tower. Application a compression force to the inner surface of the boss tower to hold both components together with adequate holding force and without damaging the boss tower components result in HGA torque retention. Measurements of HSA KPIV after swaging obtained from deformation of base plate and arm pad together. Due to hard disk drive is dynamically developed by increasing in the areal density and reducing in size, thus the arm pad is thinned. This study focuses on reducing of the swage effect by control outer arm pad deformation to maintain HSA performance. HGA torque retention was considered to reduce gap to arm and to avoid HSA resonance while swaging quality was similar. The 3-D FE method was used for analysis. The analysis and experiment show that HGA torque retention and the arm aperture modified was almost linear. Furthermore, the reduction of arm deformation and gap to arm cause increasing in HSA performance. The arm aperture can be modified for manufacturability.
Determination of the Elastic Characteristics of Bodies with Thin Coatings
Authors: Ogar Petr M. , Tarasov V.A.
Published: March 2013

We Consider a Layered Elastic Body, Consisting of Base Material with Young's Modulus E0 and Poisson's Ratio ν0 and Coating Thickness δ, Respectively, with E1 и ν1. the Thickness of the Base Is much Greater than the Thickness of the Coating. A Stiffness Model of the Layered Body with Loading His Axisymmetric Load, which Allows to Determine its Elastic Characteristics Is Proposed. the Quantitative Effect of the Relative Thickness of the Coating, the Ratio of the Elastic Properties of the Materials and Forms of the Applied Load Is Shown. an Expression for Determining the Elastic Modulus of the Coating when the Effective Modulus of Elasticity of the Layered Body Indentation Determined by the Method of Oliver-Farr Is Got. the Thickness of a Covering and Elastic Constants of the Main Material and Intentor Are Thus Considered.
An Easily Realizable Band-Notched UWB Antenna
Authors: Tseng Ching Fang , Lu Shu Cheng
Published: March 2013

An easily realizable ultrawideband (UWB) monopole antenna, with band-notched characteristics, is presented. The antenna consists of a circular metal radiation patch, fed by a 50-Ω microstrip transmission line and a rectangular ground plane with a notch cut into it. By etching a modified U-shaped slot in the radiating patch and by properly tuning its location and form, band-rejected filtering properties can be achieved easily in WiMAX/WLAN bands. It has good omni-directional radiation patterns in H-plane and a good agreement between simulation and measurement.
Polyurethane Coating on a Supporting Layer of Polymeric Nanofibers
Authors: Knížek Roman , Fridrichová Ludmila , Miková Petra , Bajzík Vladimír
Published: March 2013

Suitability of nanofiber layers for various applications is given by their morphological structure and physical properties. Structure of polymer nanofibre layers is characterized by very small diameter of the fibers and by large specific surface. For these features can polymer nanofibre membranes be widely used for special purposes- sport ,army and outdoor clothing. Thanks to the diameter and large specific surface the polymer nanofibre layers were used as a supporting structure for polyurethane hydrophilic coating. The main goal was to create 100 per cent wind resistant and water resistant coating with increased ability of steam permeability.
A Partial Narrow Mesa Superjunction IGBT
Authors: Liu Bo , Lin Xin Nan , Jiang Frank X.C. , He Jin
Published: March 2013

APartial Narrow Mesa (PNW)SJ IGBT structure is proposed in this paper.With a non-connected SJ implemented inthe PNW IGBT,the proposed structure combines the injection enhancement effectsfrom bothPNW and SJ structure,which improvesthecarrier concentrationnear the cathode sideand reducesthe on-state voltage drop.Meanwhile, the implementationof theSJ structure improvesthe blockingcapabilityat an equivalent device thickness and reduces the turn-off loss. Therefore,the proposed structure has a better Vce and Eofftrade-off. These advantages have beendemonstratedby 2-Dnumerical simulation.
Design and Implementation of the T5557 RF Card Reader
Authors: Nan Yi Min
Published: March 2013

For the convenience of reading and writing ATMEL company TEMIC series radio frequency card T5557, STC11F32XE as the main chip, developed T5557 RF card reader. Based on reader hardware master computer software also developed. Master computer software developed on the platform of VC++, MSComm control for master and slave computers communication. This paper introduces the card reader circuit, relative to the use of radio frequency card reading and writing base station chip, greatly reduced the cost.
Design and Analysis of a Novel Interleaving LLC SMPS with Load Current Sharing Performance
Authors: He Jun Ping , Wang Jin Lu , Bai Guo Zhuang
Published: March 2013

LLC series resonant topology has been widely adopted in many kinds of power converters for its high frequency, high efficiency and high power density advantages. However, the ordinary topology of a single-phase LLC is not fit to be used in low-voltage high-current output field for its relative larger output voltage ripple. In order to provide a low voltage and high current output using a LLC topology, a novel interleaving LLC switched-mode power supply design was proposed to reduce output voltage ripples ripple in this paper. This design used two hardware measures to automatically ensure a good load current sharing effect between two-branch LLC circuits and avoid the PFM difficulties of the active current sharing methods. The principles and design procedures of this novel LLC converter were introduced in detail and verified by Saber simulation results. A 1.5kW DC/DC prototype was built up in the end and the experiment results showed that a good current sharing performance was achieved.
Self-Regulation of Neighborhood Parameter for Locally Linear Embedding
Authors: Hui Kang Hua , Li Chun Li , Xu Xin Zhong , Feng Xiao Rong
Published: March 2013

The locally linear embedding (LLE) algorithm is considered as a powerful method for the problem of nonlinear dimensionality reduction. In this paper, a new method called Self-Regulated LLE is proposed. It achieves to solve the problem of deciding appropriate neighborhood parameter for LLE by finding the local patch which is close to be a linear one. The experiment results show that LLE with self-regulation performs better in most cases than LLE based on different evaluation criteria and spends less time on several data sets.
Description and Improvement of Civil Engineering
Authors: Li Wei , Li Ying
Published: March 2013

Civil engineering deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings. As one course in professional engineering discipline, Civil Engineering is offered to undergraduate students. It aims to let students know environmental engineering, geotechnical engineering, geophysics, geodesy, control engineering, structural engineering, biomechanics, nanotechnology, transportation engineering, earth science, atmospheric sciences, forensic engineering, municipal or urban engineering, water resources engineering, materials engineering, coastal engineering, surveying, and construction engineering. It requires to be constructed to keep it up-to-date with current development of civil engineering. Based on analysis of the current conditions of this course and aims for construction, it describes a construction plan, including revision of the teaching content, compiling of the textbook, improvement of teaching methods and class modes, preparation of test database and exercise database.
Atomic Force Microscope Deposition Assisted by Electric Field
Authors: Liu Zeng Lei , Jiao Nian Dong , Wang Zhi Dong , Dong Zai Li , Liu Lian Qing
Published: March 2013

This paper introduces atomic force microscope (AFM) deposition method to fabricate nanostructures and nanodevices. Field emission theory is introduced in this paper, which provides theoretical explanation for AFM deposition. Dot matrixes are fabricated by AFM deposition on three different substrates, Si, Au and GaAs. Differences of deposition on the three substrates are discussed. AFM deposition has many practical applications. For example, AFM deposition can be used to solder nano components together to improve electrical properties of nanodevices. Besides nanosoldering, AFM deposition can also be used in fabrication of nanodevices. Thus AFM deposition is a valuable research field for future massive applications of nanodevices.
Design and Test of High-g MEMS Accelerometer
Authors: Wen Feng , Shi Yun Bo , Ren Yong Feng
Published: March 2013

For measuring the high-g impaction and overload of some conditions, a kind of high-g accelerometer was designed. Testing and analysis to the accelerometer was processed through launching projectile to penetrate concrete target. Four fixed end structure was adopted in the design of the high-g accelerometer and the chamfer was set in the bottom and top part of the beam to divert stress. It is learned that the sensitivity of the accelerometer is 0.1uv/g by calibration. A kind of deceleration measurement device was provided to test the performance of the accelerometer through penetration experiment over concrete target and the design of the measurement device and penetration experiment over concrete target was illustrated. The impaction characteristic of the accelerometer was tested and studied through penetration to the target. MATLAB software is used to analyze the influence of the filter cutoff frequency over the test result and the best cutoff frequency point was set at 6 kHz, under which the maximum penetration acceleration is up to 28526 g.
Metal Adsorbent Prepared from Coir Pith as Agricultural Waste: Adsorption of Zn(II) and Pb(II) from Aqueous Solution
Authors: Wantala Kitirote , Pojananukij Nusavadee , Sriprom Pongsert , Kumsaen Tinnakorn , Neramittagapong Arthit , Neramittagapong Sutasinee
Published: March 2013

Adsorption of Zn(II) and Pb(II) from aqueous solution were studied by using modified coir pith as an adsorbent. The extended adsorption conditions were investigated as a function of calcination temperature, contact time, adsorbent size, initial pH of solution and initial Zn(II) and Pb(II) concentrations. The adsorption capacity increased rapidly in first 5 minute and reached equilibrium in 120 minutes for Zn(II) and 10 minutes for Pb(II). In case of Zn(II); the results showed that the calcination temperature of modified coir pith above 600oC gave the higher adsorption capacity. The sizes of modified coir pith have no effect on the adsorption capacity. The adsorption capacity increased with increasing initial solution pH value. In case of Pb(II); the calcination temperature of modified coir pith showed no effect on the adsorption capacity. The sizes of modified coir pith showed a little effect on the adsorption capacity. The adsorption capacity increased with increasing of initial solution pH value up to pH of 3 and then stable. The results also corresponded with the Langmuir and Freundlich isotherms and pseudo second order kinetic adsorption models. The modified coir pith gave a higher Zn(II) and Pb(II) adsorption capacity of 29.33 mg Zn(II)/g adsorbent and 36.50 mg Pb(II)/g adsorbent, respectively.
Optical Band Gaps and Electrical Conductance of Si Nanocrystals in SiO2 Matrix for Optoelectronic Applications
Authors: Fangsuwannarak Thipwan , Khunchana K. , Rattanachan S.T.
Published: March 2013

In this study, silicon nanocrystal (Si-nc) films were synthesized by compositing of Si-nc powder embedded in silicon oxide phase. The Si-nc film produced by the spin-coating methode using Tetraethylorthosilicate, ethanol, phosphoric acid, and Si-nc powder as suspension precursors. The variation in structural and optical properties of Si-nc sol films with the amounts of Si-nc powder have been characterized. Atomic force microscopy (AFM) shows that low density level of Si-nc power can result in the amount of porosity in the Si-nc films. It is found that when the Si-nc films have the higher Si-nc density, the small pores in the SiO2 phase were removed. In addition, optical energy gap (Eg) of Si-nc samples was evaluated by the Tauc plot method. It is a crucial attribute for a promising photonic device. The obtained optical bang gap values were extended from 1.10 eV to 1.40 eV as compared with the typical Si bulk. In addition, density of Si-nc clusters has a considerable effect on the electrical conductance of the Si-nc films measured at room temperature.
Tribological Properties of PM Cu-Based Dry Friction Clutch
Authors: Prapai Jirapat , Morakotjinda Monnapas , Yotkaew Thanyaporn , Vetayanukul Bhanu , Tongsri Ruangdaj , Kamsuwan Panya , Yoshino Masahiko
Published: March 2013

Sintered Cu-based frictional materials were developed by using powder metallurgy (PM) method. The materials are aimed for application in a passenger car as a dry friction clutch. Effects of sintering temperature and composition on mechanical and tribological properties were determined. It was found that improper frictional material formulations caused inferior properties, particularly when the sintering temperatures were increased. Admixing of high Sn content (8 wt. %) resulted in decreases of sintered density and hardness with increasing sintering temperature. High Sn contents caused swelling of the sintered materials. Tribological properties (friction coefficient and wear rate) of the sintered specimens of the investigated materials were insensitive to sintering temperatures in the range of 800-950 °C but they were strongly influenced by chemical compositions. Addition of 3 wt. % graphite lowered the friction coefficient, which subsequently lowered the wear rate of the sintered material. To increase friction coefficient, one of the crucial properties of the dry friction clutch, of the sintered Cu-based frictional materials, two approaches were employed. In the first approach, substitution of graphite by SiO2 powders could improve the material friction coefficient. In the second approach, decreases of graphite content from 3 to 1 wt. % and of Sn content from 8 to 2 wt. % were conducted. The latter approach not only improved friction coefficient but also improved sintered density and hardness of the Cu-based frictional materials.
High Indentation Resistance of Aluminum Borate Based Glass-Ceramics
Authors: Sooksaen Pat , Prasertcharoensuk Pisud , Damnernsawat Jiraporn , Pattamawitayanimit Nimit
Published: March 2013

This study investigated the bulk crystallization of 54B2O3-19SiO2-17Al2O3-5BaO-5MgO (mol%) glass. Melting was carried out at 1500°C for 1 h using a bottom-load electric furnace. The glass melt was cast into a block and annealed at 500°C for 2 h. Isothermal heat treatment was carried out at 1100°C for 2, 4, 8, 16, 32 h to form bulk crystallized glass-ceramics using a heating and cooling rate of 5°C/min. Phases present in the glass-ceramic samples were studied by x-ray diffraction. Crystalline Al4B2O9 and Al18B4O33 were the main phases and the phase stability depended on the isothermal time. Microstructures were observed by a scanning electron microscope. The size of aluminum borate whiskers/rods tend to increase with longer isothermal holding period. The whisker/ rod-like crystals uniformly oriented throughout the microstructure in all heat treated samples. This led to interlocking microstructure and hence an increase in hardness and fracture toughness. Glass-ceramics synthesized at longer heat treatment times resulted in an increase in the surface hardness and shorter path length at the corner of the diamond pyramid-shaped indenter. Glass-ceramics synthesized in this study can be applied as high temperature resistant machinable materials because their microstructures can resist micro-cracking upon indentation.
Preparation of 3DP Hydroxyapatite Composite by Single and Double Pass Poly(ε-caprolactone) Infiltration
Authors: Thammarakcharoen Faungchat , Suwanprateeb Jintamai
Published: March 2013

Recently, porous hydroxyapatite was fabricated by three dimensional printing (3DP) in coupled with low temperature phosphorization to yield nanosized and low crystalline structure. However, brittleness was an intrinsic drawback for some foreseen applications. Polymer infiltration aiming to improve the toughness and mechanical integrity was thus carried out using biodegradable poly(ε-caprolactone) (PCL) as an infiltrant since it has shown good biocompatibility together with a high elongation and energy to failure as compared to other medical polymers. Three routes of infiltration were performed including melt infiltration of low molecular weight PCL (Mw ˜ 10,000), solution infiltration by 10 % high molecular weight PCL (Mw ˜ 80,000) and the combination of both melt and solution infiltration of low and high molecular weight PCL. The combination of low and high MW infiltration yielded the greatest increase in the mechanical properties and followed by the melt infiltration of low molecular weight PCL while the use of high MW infiltration yielded limited enhancement. After immersing in simulated body fluid (SBF), no significant changes in flexural properties were seen for both hydroxyapatite and high molecular weight infiltrated sample. However, flexural strength and strain at break of low molecular weight infiltrated sample largely dropped after 7 days of immersion to be closed to those of hydroxyapatite and high molecular weight infiltrated sample. The flexural properties of high-low infiltrated sample also decreased after immersion, but to a less degree and still maintained the greatest values amongst all samples. This could be associated to the difference in degradation of different molecular weight of PCL and the content of polymer infiltration induced by different infiltration routes. Calcium and phosphorus ions in the SBF were quantified and observed to be consumed continuously during immersion for all samples. Newly formed apatite crystals were observed to form on the surface of the infiltrated composites signifying that infiltration did not hinder the bioactivity of the composites.
Research on the Residual Stress of Aluminum Alloy (LF6) Welding
Authors: Guo Zhi Qing , Lv Qiu Juan , Li Yan Jiao , Liu Chang Jiang , Xie Fang
Published: March 2013

This paper use the software ANSYS to study the aluminum alloy (LF6) welding residual stress by numerical simulation and experimental study. The result indicates that the aluminum alloy (LF6) has the same residual stress distribution with others, there is a maximum value existing at the range of 4-5mm near the welding seam.
Research on Gear Repairing Technology by Laser Cladding
Authors: Shi Juan , Bai S.Q.
Published: March 2013

Wearing gears with complex tooth surface are difficult to repair. A test method of laser cladding was made to repair the damaged gears which were made by steel 45, with synchronous powder feeding and gear axial scanning method, and Ni45 powder as cladding material. The relative position of laser beam and the gear surface were designed to solve the interference problems in laser cladding process. It analyzed the morphology of the cladding layer in the different test conditions to get optimum parameters, and determined the cladding thickness and overlapping ratio, and optimal sequence by made a comparison of cladding quality in different condition. Microscopic metallographic analysis and hardness testing were made for the cladding layer to analyze the performance of cladding layer. Got high strength cladding layer on damaged gears tooth surfaces. Laser cladding method can repair the gear surfaces and raise the wear resistance.
Determination of the Onset of the Dynamic Recystallization of a 7075 Al Alloy
Authors: Mikó Tamás , Barkoczy Peter
Published: March 2013

This paper presents an investigation about the occurrence of the dynamic recrystallization (DRX) during hot forming. Two 7075 aluminum alloy samples in different initial states were examined by compression tests at temperatures between 573 K and 723 K and constant strain rates ranging from 0.002 to 2 (s-1) with the maximum strain of 0.5 mm/mm. The activation energies of the examined aluminium were calculated, being 137.7 kJ/mol and 142.4 kJ/mol. The critical stresses and strains for the initiation of the dynamic recrystallization were determined using a numerical method based on the changes of the work hardening rate (θ) as a function of the flow stress (σ) or a strain (ε), respectively. Based on the micrographs taken after the deformations it was revealed that in some cases only dinamyc recovery (DRV) whereas in others DRX occurred under the applied examination conditions. The critical stress which belongs to the onset of the DRX or the DRV depend on the temperature, the strain rate, and the initial grain size. The critical and maximal stresses and the corresponding strain values at different conditions were determined. In the examined range of deformation, temperature and strain rate, the critical rations are σ_c/σ_p= (0.93-0.99) and εc/ εp = (0.3-0.74), respectively.
The Effect of Micro-Impulse Current on the Morphology of Tin Electrodeposited from Chloride Solutions
Authors: Kulcsár Tibor , Dobó Zsolt , Kékesi Tamás
Published: March 2013

A flexible and efficient process of tin electrorefining has been devised, using aqueous solutions of relatively low HCl and tin chloride concentrations. Any additives have been avoided, which enhances purity but also incurs the difficulty of obtaining compact cathode deposits. This feature is however assisted by the natural inhibition in complexing chloride solutions and the modulation of the current. Due to the rough dendritic crystal growth, special provisions are required to avoid short circuiting. Using short pulses in the 50-250 μs range of periodically reversed or interrupted currents, the lengths of the usually large dendrites can be moderated. The periodic current with extremely short cycle times and special electrode arrangement can be utilized for averting short circuits and for achieving better coverage of the cathode surface. This technique can be applied efficiently to obtain pure tin from soldering waste materials.
Microstructure Characterization of Deep-Drawn DP780-Grade Dual Phase Steel
Authors: Filep Adám , Mertinger Valéria
Published: March 2013

Dual phase (DP) steels belong to the group of high-strength low-alloy (HSLA) steels. Our study focuses on the causes of crack formation of sheets, which are designed for deep drawing, of DP780-grade dual phase steel. Also, a series of heat treatment experiments were performed regarding the effect of intercritical annealing temperature on the structure and mechanical properties of the finished product (in this case a rolled sheet).
Formation of Annealing Twins during Recrystallization and Grain Growth in 304L Austenitic Stainless Steel
Authors: Jin Yuan , Bernacki Marc , Rohrer G.S. , Rollett Anthony D. , Lin B. , Bozzolo Nathalie
Published: March 2013

Understanding of the mechanisms of annealing twin formation is fundamental for grain boundary engineering. In this work, the formation of annealing twins in a 304L austenitic stainless steel is examined in relation to the thermo-mechanical history. The behaviour of annealing twins of various morphologies is analysed using an in-situ annealing device and EBSD. The results confirm that there is a synergistic effect of prior strain level on annealing twin density generated during recrystallization. The higher the prior strain level, the higher the velocity of grain boundary migration and the higher the annealing twin density in the recrystallized grains. This effect decreases as the recrystallization fraction increases. The existing mathematical models (Pande's model and Gleiter's model), which were established to predict annealing twin density in the grain growth regime, can not predict this phenomenon.
Effect of Micro-Alloying Elements of Ti, Nb and B on Recrystallization Behavior of Cold-Rolled Interstitial-Free Steel Sheets
Authors: Song Xin Li , Peng Kun , Yuan Ze Xi , Zhu W.W. , Jia J. , Deng Z.J.
Published: March 2013

The effect of micro-alloying elements of niobium and boron and titanium on recrystallization behavior is researched after the cold rolled IF steels are annealed at high temperature. The results show that there is high density dislocation in the cold rolled steel and the microstructure is fibrous tissue. The recrystallization grains appear when the cold steel annealed at 655 °C and then the grains grow up with the annealing temperature increased to 840 °C. The recrystallization temperature and time of B-Ti-IF steel is lower than that of Nb-Ti-IF and Ti-IF steels. The recrystallization activation energy of Nb-Ti-IF steel is 181.7KJ/mol which is 56.6KJ/mol larger than that of B-Ti-IF steel.
In Situ Measurements of Grain Growth and Recrystallization by Laser Ultrasonics
Authors: Matthias Militzer , Garcin Thomas , Poole Warren J.
Published: March 2013

Laser ultrasonics for metallurgy (LUMet) is an innovative sensor technology for in-situ measurement of microstructure evolution during thermomechanical processing. This unique sensor has been attached to a Gleeble 3500 thermomechanical simulator for dedicated laboratory studies during processing of steel, aluminum, magnesium and titanium samples. Advanced processing software has been developed for the measurement of grain size and texture evolution from laser ultrasonic signals. Results of austenite grain growth measurements in low carbon steels will be described to demonstrate the capabilities of the LUMet technique. Further, applications of the system to measure recrystallization of ferrite and austenite formation during intercritical annealing simulations of dual phase steels will be presented. The ability to rapidly acquire data both during a single test and for multiple conditions over a range of conditions from different samples has important implications on expediting process modelling and alloy design. Although certain limitations exist, the LUMet technique offers a very reliable characterization platform with a number of potential applications in metallurgical process engineering.
Regularities of Grain Refinement in an Austenitic Stainless Steel during Multiple Warm Working
Authors: Belyakov Andrey , Tikhonova Marina , Yanushkevich Zhanna , Kaibyshev Rustam
Published: March 2013

The structural changes that are related to the new fine grain development in a chromium-nickel austenitic stainless steel subjected to warm working by means of multiple forging and multiple rolling were studied. The multiple warm working to a total strain of 2 at temperatures of 500-900C resulted in the development of submicrocrystalline structures with mean grain sizes of 300-850 nm, depending on processing conditions. The new fine grains resulted mainly from a kind of continuous reactions, which can be referred to as continuous dynamic recrystallization. Namely, the new grains resulted from a progressive evolution of strain-induced grain boundaries, the number and misorientation of which gradually increased during deformation. In contrast to hot working accompanied by discontinuous dynamic recrystallization, when the dynamic grain size can be expressed by a power law function of temperature compensated strain rate as D ~ Z-0.4, much weaker temperature/strain rate dependence of D ~ Z-0.1 was obtained for the warm working.
Texture and Structure Study of AZ41 Alloy after ECAP and Annealing
Authors: Serebryany Vladimir N. , Djyakonov Grigory S. , Salishchev Gennady A. , Kopylov Vladimir I. , Dobatkin Sergey V.
Published: March 2013

Equal channel angular pressing (ECAP) of magnesium alloys dramatically effects the texture and structure of the alloys due to processes of severe plastic deformation and dynamic recrystallization. Changes in texture, structure and tensile properties of AZ41 alloy after ECAP by Bc regime with 4 passes at a temperature of 245° C and subsequent annealing were studied. Evaluation of texture and structure was performed using the orientation distribution function (ODF) restore from the X-ray direct pole figures and the large number of individual orientations measured by the EBSD method. After ECAP the structure of the dynamically recrystallized fine grains with an average size of about 2,9 μm was revealed. The ratio of the volume fraction of low angle grain boundaries (LAGBs) to the high angle grain boundaries (HAGBs) constituted as 1:3. The formation of few basal texture, tilted by 45 ÷ 55 ° to the pressing direction was also found. Subsequent annealing increases the grain size to 10 μm, the fraction of HAGBs - up to 85% and practically does not change the texture type. These changes in structural parameters improve considerably the low-temperature ductility of AZ41 alloy.
Using Visible Implant Elastomer to tag insects across life stages: a preliminary investigation with blow flies (Diptera: Calliphoridae)
Authors: Moffatt Colin
Published: March 2013

Visible Implant Elastomer (VIE) has previously been used successfully to tag individuals in a variety of marine and amphibious animals, earthworms, and scorpions. Visible Implant Elastomer tags were injected into third instars of the blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) to test its compatibility and retention across life stages. Injecting into the dorsal midline of the 11th segment (seventh abdominal segment) produced survival rates of 80%, with no significant difference in the subsequent rate of development (z = 0.21, P = 0.83) as compared with untagged insects. Tags remained visible and allowed identification of individuals within a feeding, intermingling aggregation (maggot mass), especially when a high-contrast fluorescent colour was used. Tags were retained across life-stage changes and were easily found in dissected adults.
Setting up a structured laboratory mentoring programme
Authors: Maruta Talkmore , Rotz Philip , Peter Trevor
Published: March 2013

Introduction: Laboratory mentoring programmes can be an important vehicle to establish and solidify quality management systems and help laboratories achieve accreditation goals. Different mentoring approaches have been used with varying levels of success. The authors provide a guide to implementing a structured laboratory mentorship programme based on their practical field experience.Method: The study is based on experience in Lesotho as well as subsequent roll out of a similar approach in the other African countries of Zimbabwe, Mozambique, Swaziland and Cameroon between 2009 and 2011.Summary: We highlight critical elements to consider when setting up a long-term, sustainable and well-structured mentorship programme. These elements include: well-defined goals; sufficient length of mentor engagement on site; standardised approach across laboratories; measurement of progress using standardised tools; well-structured reporting mechanisms; alignment of the programme with overall Ministry of Health plans; and selection and training of the mentors. These elements will differ in application, depending on countries’ needs and available resources. A structured approach allows for scalability, comparison across laboratories and countries and an easier approach to budgeting and planning for countries intending to set up similar programmes.