bluuebunny/crossref_metadata_2025 huggingface dataset:
Maneuver Control and Vibration Suppression of a Smart Flexible Satellite Using Robust Passivity Based Control
Authors: Azadi Mohammad
Published: March 2012

In this paper a satellite with two flexible appendages and the piezoelectric layers which are attached to them and a central hub is considered. The piezoelectric layers are used as actuators. The governing equations of motion are derived based on Lagrange method. Using Rayleigh-Ritz technique ordinary differential equations of motion are obtained. A robust passivity based control is applied to the system to not only control the three axes maneuver of the satellite but also suppress the vibrations of the flexible appendages. Finally, the system is simulated and simulation results show the good performance of this controller.
Design and Analysis of Front Axle for Two Wheel Drive Tractor
Authors: Oyyaravelu R. , Annamalai K. , Kumar M. Senthil , Naiju C.D. , Michael Joel
Published: March 2012

Fatigue failure has become a major concern in the automobile and aircraft industry, heavy machinery etc. Failures by fatigue are especially dangerous because they are unpredictable; giving no prior notification of the imminent failure they occur suddenly. Front axle of tractor is one of the major and very important components that undergo severe load conditions and it fails unexpectedly causes unrecoverable losses. The objective of this study is to analyze the existing design of the front axle of the tractor for service load conditions and redesign to its functional requirements and to increase its life expectations. Finite element simulation is carried out for the existing front axle using ANSYS. The critical location of the front axle has to be identified and redesigned to ensure the safety. The existing geometry of the front axle is modified to the optimum size which suits for functional requirements with increased life and minimum cost. In this analysis, the geometry of the front axle is modified and a new design is proposed. The life expectancy of the front axle was predicted for the dynamic load using ANSYS fatigue design module.
Kalman Filter-Based Sensor Fusion for Improving Localization of AGV
Authors: Lee In Seong , Kim Jae Yong , Lee Jun Ha , Kim Jung Min , Kim Sung Sin
Published: March 2012

This paper proposes localization using sensor fusion with a laser navigation and an inertial navigation system for indoor mobile. The laser navigation is a device that measures angle and distance between the robot and the reflectors. Although it is the high-precision device for indoor global positioning, there is a problem that the accuracy of laser navigation significantly drops while moving at high speed and rapid turning. To solve this problem, the laser navigation was fused to inertial navigation system through Kalman filter. For experiment, we use omnidirectional robot with Mecanum Wheels and analyze the positioning accuracy according to driving direction of the robot.
Fracture Behaviour of Chemically Treated Reshira-Epoxy Composite and Optimization of Parameters for Composite Fabrication
Authors: Vasumathi M. , Vela Murali
Published: March 2012

Natural fiber composite is nowadays used as an alternative to conventional materials. In this work, the natural fibre, Reshira is tried with epoxy resin, for the first time, as a composite material to be used for various applications. The reshira fiber is chemically treated with sodium hydroxide for better adhesion between fibre and resin. The reshira fiber–epoxy composite is fabricated with varying chemical concentrations of sodium hydroxide solution, fiber lengths and fiber volume fractions. The composite samples are subjected to tensile, flexural and impact tests and the optimum composition that produces maximum mechanical performance is selected. Further the optimum sample is tested for its fracture toughness property.
Intelligent Traffic Flow Parameters Acquisition System Base on GPS
Authors: Zhang Jing , Li San Cai , Yang Zhao Hui , Yang Wu Gang
Published: March 2012

In order to get the accurate traffic flow parameters, it often takes too long time and a lot of manpower and material resources. So, combined with GPS vehicle positioning system and the characteristics of traffic flow parameters, the transformation model of traffic parameters in intelligent acquisition system of traffic flow parameters is designed and the data processing and error recovery method are present. The results show that the system, integrated fully the advantage of GPS, can transform GPS coordinates into the features of traffic flow parameters directly, which has an intuitive guide to the traffic management department.
Research on the Strength Improvement of 7A04 Aluminum Alloy
Authors: Yi Chao Jue , Zhai Peng Cheng , Dong Li Zhou , Fu Qi Hao
Published: March 2012

By using cryogenic treatment on 7A04 aluminum alloy tested with micrographic analysis and mechanical properties test, we studied the impact on mechanical properties of 7A04 aluminum alloy The results showed that the strength of 7A04 aluminum alloy could be highly increased and the grain size would be reduced in the process through being treated in 480°C/80min + aging in 120°C/4h + cryogenic treatment + aging at 120°C/16h.7A04 aluminum alloy are more fully recrystallized to grain refinement and the tensile strength of it can be increased to 720Mpa after the treatment.
Densification Behavior of Steatite by Two Stage Sintering
Authors: Jeffrey C.K.L. , Ramesh S. , Tan C.Y.
Published: March 2012

Structural materials, such as steatite-based ceramic is considered one of the most useful engineering ceramic in place of alumina as a cost-effective way to meet performance requirements. The objective of the research here is to develop a dense body which exhibits good properties as mentioned by the two stage sintering method. Steatite powders used in this work were undoped steatite, steatite doped 20wt% ZnO and steatite doped 20wt% MnO2. The green samples were cold-isostatically pressed and pressureless sintered at temperatures ranging from 950°C to 1200°C at heating rate of 10°C/min through two stage sintering before cooling down to room temperature. The results revealed an improvement in the densification of all the steatites through two stage sintering compared to the conventional sintering. At 1200°C, the steatite bodies with 20 wt% ZnO compositions achieved maximum bulk density of 2.79 g/cm3 which is 10.3% higher than the same steatite doped bodies which exhibited best result when it was conventionally sintered. As a result of bulk density improvement, two stage sintering exhibited outstanding effects in enhancing Young’s modulus and hardness of the steatite body.
Optical Behaviour of Transparent Thin Films of Sr-Doped TiO2 for Optoelectronic Devices
Authors: Mangrola M.H. , Parmar B.H. , Pillai A.S. , Joshi Vibhutikumar
Published: March 2012

Transparent thin films of 3% Sr – doped TiO2 were prepared by spin coating technique on a glass substrate and annealed at different temperatures. The optical properties of the films were studied using UV – Visible spectroscopy and Photoluminescence ( PL ) spectroscopy. The optical band gap is found to change with the annealing temperature of the deposited films. The PL emission spectra showed a sharp intense peak near the violet region. AFM analysis was used to study the surface topography of the films. The study shows potential applications of the prepared films in optoelectronic devices.
Polymeric Antioxidant Based on Natural Rubber Grafted with N-(4-Hydroxyphenyl)maleimide
Authors: Klinpituksa Pairote , Somkieowan Sittaporn , Waehamad Wae Asae , Lopattananon Natinee
Published: March 2012

A novel rubber bound antioxidant NR-g-HPM was prepared by melt grafting HPM (N-(4-hydroxyphenyl)maleimide) onto natural rubber in a brabender plasticorder. HPM was synthesized from p-aminophenol and maleic anhydride. The yield was found to be over 80%. The grafting products were observed with FTIR spectroscopy and TGA. The ageing resistance of natural rubber vulcanizates using NR-g-HPM was studied. It was found that an optimal amount of NR-g-HPM (6 phr) gave about 25% better tensile strength and elongation at break as compared with conventional BHT addition, for filled natural rubber after 48 h of accelerated aging.
Synthesis and Characterization of Fluorescent Acrylamide Water Soluble Macromer
Authors: Kraisiri Datchanee , Chantarasiri Nuanphun , Pimpan Vimolvan
Published: March 2012

Fluorescent acrylamide water soluble macromer was synthesized from dimethylaminopropylmethacrylamide-9-(chloromethyl)anthracene quaternary ammonium salt monomer using an inverse emulsion polymerization method. It was initiated by benzoylperoxide and stabilized by a co-emulsifier system consisting of Span®80 and Tween®60 dispersed in a continuous phase of cyclohexane with HLB value of 6.42. The polymerization was done at 80°C for 4 hours. The obtained macromer exhibited similar functional groups, ultraviolet-visible absorption and fluorescent emission but different solubility when compared to the monomer. Further analyses by proton nuclear magnetic resonance spectroscopy and mass spectrometry revealed the chemical structure of the macromer as a dimer of the monomer containing carcon-carbon double bonds.
Photocatalytic Degradation of Active Brilliant Red on TiO2/SiO2 Composite Catalysts
Authors: Cao Chun Hua
Published: March 2012

TiO2/SiO2 composite catalysts were prepared using two-step sol-gel method, with tetrabutyl titanate and tetraethyl orthosilicate as the main raw materials, and its photocatalytic properties for degradation of active brilliant red X-3B solution were researched throuth Ti:Si molar ratio, calcined temperature, initial concentration and photocatalyst dosage. The results indicate that the TiO2/SiO2 composite catalysts prepared with Ti:Si molar ratio of 6, calcination at 500°C have the best photocatalytic activity, and the photocatalytic activity of the composite materials is higher than that of pure TiO2 under the same conditions; moreover, it was found that degradation rate of active brilliant red X-3B solution increased with its lower initial concentration, and the optimum dosage of composite photocatalysts is 1.6g/L when the initial concentration of active brilliant red X-3B solution is 25mg/L.
Free Vibration Analysis of FGM Sandwich Beams Containing Edge Cracks
Authors: Rad Javad Soltani , Tivay Ali , Sadighi Mojtaba
Published: March 2012

This paper presents a vibration analysis of sandwich beams with functionally-graded skins containing edge cracks. Finite Element models of FGM sandwich beams are created with different depths and locations of the edge-cracks, and the first four natural frequencies of the beam are obtained for each crack configuration. The integrity of the data is validated for the FGM skins in comparison to a previously published reference. Finally, an inspection is conducted on the data to show the influences of the location and depth of cracks and material properties on the flexural vibration characteristics of cracked FGM sandwich beams.
Effects of Aggregate Gradation on Water Permeability of Concrete
Authors: Warda Bint Ashraf , Munaz Ahmed Noor
Published: March 2012

Concrete permeability is one of the key properties of concrete which largely effects concrete durability. Conventionally concrete permeability is considered as a function of water to cementitious materials ratio. But aggregate being the major constituent of concrete, was found to have considerable effects on various properties of concrete. In this research the effects of aggregate gradation on concrete permeability have been examined for two different types of cement. Total twenty concrete mixes were prepared using two different types of aggregate gradations, CEM I and CEM II/B-M cements. Concrete permeability measured in terms of depth of water penetration under pressure as per the standard EN12390-8. It has been found that concrete mixtures having same w/c ratio and keeping all other properties same, may have different permeability only because of different aggregate gradation. This article also features the use of concrete compressive strength as an alternative parameter for controlling concrete permeability based on the test results.
Research of Ecological Planning of River Landscape Used Ecological Concrete
Authors: Yang Zhang Wei
Published: March 2012

Ecological concrete has been playing an improving important role in normal life. Ecological concrete is a kind of concrete, with greater porosities, which can be used in public road, river bank engineering and so on. In this work, we proposed a way of researching ecological planning of river used Ecological concrete.
Reduction in Defect Rate by Taguchi Method in Plastic Injection Molded Components
Authors: Dangayach G.S. , Kumar Deepak
Published: March 2012

In the present era, competition gets tougher; there is more pressure on manufacturing sectors to improve quality and customer satisfaction while decreasing cost and increasing productivity. These can be achieved by using modern quality management systems and process improvement techniques to reduce the process variability and driven waste within manufacturing process using effective application of statistical tools. Taguchi technique is well known technique to solve industrial problems. This technique is fast and can pinpoint the chief causes and variations. Plastic injection molding is suitable for mass production articles since complex geometries can be obtained in a single production step. The difficulty in setting optimal process conditions may cause defects in parts, such as shrinkage and warpage. In this paper, optimal injection molding conditions for minimum shrinkage were determined by the Taguchi design of experiment (DOE) approach. Polypropylene (PP) was injected in circular shaped specimens under various processing parameters: melt temperature, injection pressure, packing pressure and packing time. S/N ratios were utilized for determining the optimal set of parameters. According to the results, 2400 C of melt temperature, 75 MPa of injection pressure, 50 MPa of packing pressure and 15 sec. of packing time gave minimum shrinkage of 0.951% for PP. Statically the most significant parameter was melt temperature for the PP. Injection pressure had the least effect on the shrinkage. The defect rate was reduced from 14% to 3%.
Effects of Temperature, Strain Rate and Grain Size on Superplastic Behavior of Magnesium
Authors: Soomro Muhammad Waseem , Neitzert Thomas Rainer
Published: March 2012

The influence of temperature, grain size and strain rate on superplasticity of magnesium is investigated. Different approaches are compared along with their experimental results to show the variation in the amount of superplasticity by varying above mentioned parameters. At room temperature magnesium alloys usually have poor formability but recent studies of some alloys such as ZE10, AZ31, AZ61 AZ60, AZ80 and AZ91 are pointing that by varying the temperature along with grain size and strain rate improved formability is possible or even superplastic forming of these alloys can be achieved to meet the demands of automotive, aircraft and other weight conscious industries.
Challenges and the Way Forward for Building Materials Management in Building Adaptation Projects
Authors: Isnin Zarina , Ahmad Sabarinah Sh.
Published: March 2012

Global sustainability issues have led Malaysia, amongst other concerned countries to develop strategies on hazardous materials identification for construction industries. However, very few published literatures are found on the effects of building materials to social health, the environment and economy in building adaptation projects. There is a promising future for better building adaptation materials management but the issues and challenges highlighted require further actions for a positive difference. Encouraging usage of greener building materials and more research could be the way forward.
Centrifugal Atomization of Zinc Metal Powder for Friction Materials Application
Authors: Sungkhaphaitoon Phairote , Plookphol Thawatchai , Wisutmethangoon Sirikul
Published: March 2012

In the present work, a centrifugal atomization was studied for producing zinc metal powder. The effect of rotating disc speed on median particle size, particle size distribution and standard deviation, production yield, and morphology of the atomized zinc powder was investigated. The atomization was carried out using graphite flat disc, melt pouring temperature, preheating disc temperature and melt feed rate of 40 mm, 550 °C, 300 °C and 50 kg/h, respectively. The atomizer disc speeds were varied from 10,000 to 30,000 rpm. It was evidenced from the experimental results that the median particle size and standard deviation of zinc metal powder decreased with increasing disc speed. The production yield tended to increase with increasing rotating speed. SEM images revealed that most zinc metal particles were irregular, elongated flakes. This kind of zinc power may be suitable for use as a friction material for manufacturing brake pad component in the automotive part industry
Anisotropy and Forming Characteristics of Magnesium Alloy ZE10
Authors: Soomro M. Waseem , Khan R. , Akhtar M.
Published: March 2012

The current work investigates anisotropy and forming characteristics of ZE10 Mg alloy. Anisotropic effects are measured by analysing tensile tests data for the specimens from 0o, 45o and 90o rolling directions of thin sheet of 0.8 mm thickness. The effects of temperature and strain rates are also included in anisotropic analyses. The mechanical properties of ZE10 alloy are affected by the physical conditions like temperature and strain rates. The effect is significant on yield strength, UTS and fracture strain while small variation is observed in case of Young’s modulus. Deep drawing experiments have been done to investigate the effects of temperature on forming characteristics and limit drawing ratio (LDR) of an alloy. Forming investigation shows that it is difficult to produce a good or unfractured part at 100 oC, but it can be produce at 150 oC or higher with different combinations of blank holder force and drawing ratio. Also, LDR and blank holder force also effects required punch force.
Effect of Al Mole Ratio on Iron Aluminide Reinforced with TiB2-Al2O3 Composite by Self-Propagating High-Temperature Synthesis
Authors: Tapsuan Kunyaporn , Sutham Niyomwas
Published: March 2012

The Fe3Al-TiB2-Al2O3 composite has been prepared by self-propagating high-temperature synthesis (SHS) from FeTiO3-B2O3-Al system. The standard Gibbs energy minimization method was used to calculate the equilibrium compositions of the reacting species. The reactions were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The effects of Al molar ratio of 4, 4.33 and 5 mole on the results product were investigated. The composition and microstructure of SHS products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The optimum result of Fe3Al intermetallics phase was obtained when using 4.33 mole of Al.
Low Temperature Synthesis of Pb(Zr0.52Ti0.48)O3 Ceramic Powders by Chelating Agent Assisted Sol-Gel Process
Authors: Jegatheesan P. , Muneeswaran M. , Gokul Raj S. , Giridharan N.V.
Published: March 2012

The Perovskite Pb(Zr0.52Ti0.48)O3 (PZT) ceramic powders were synthesized by sol-gel assisted process by using citric acid (CA), EDTA and Triethanolamine (TEA) as chelating agents. The phase evolution of the synthesized powders was investigated by powder X-ray diffraction (XRD) analysis. TEA assisted process yielded phase pure PZT powders at a relatively low temperature of 600 °C compared to CA and EDTA assisted process. Further, the phase purity of the powders were improved by sintering temperature of 800°C. Vibrational analysis of Metal-Oxygen bonding was carried out using Fourier transform infrared spectroscopic (FTIR) analysis. Showed a broad band in the spectrums between 500 cm-1 to 700 cm-1 attributed to the vibrations (Ti/Zr)O6 and Ti/Zr-O from PbZrTiO3. The morphology of the prepared powders was visualized using Scanning electron microscope. From the leakage current characteristics, EDTA assisted powder has higher leakage current densities compared to the CA and TEA assisted powders.
Effect of Grain Size on the Shape Recovery in a Melt-Spun Fe-24%Mn-4%Si-5%Cr-5%Co SMA Ribbon
Authors: Kim H.J. , Jee K.K. , Kang H.W. , Lee J.K. , Yang G.S. , Jang W.Y.
Published: March 2012

Effect of grain size on microstructure, transformation characteristics and shape recovery has been studied in Fe-24%Mn-4%Si-5%Cr-5%Co shape memory ribbons fabricated by melt spinning. Mean grain size of the ribbons could be controlled by wheel speed; in case of ribbon manufactured in the wheel speed of 10 m/sec, mean grain size was more or less 20 μm, while the mean grain size in 50 m/sec was about 1 μm. Thermal ε-martensite in the shape of plate could be observed in austenite matrix and the volume fraction of that decreased in smaller grains because of grain constraint. As a grain size decreased, one-way and two-way shape recoveries were increased. A change in shape recovery of ribbons was closely related to deformation mode i.e., transformation-induced plasticity or slip according to grain size; it could be confirmed that reversible ε-martensite was induced in preference to irreversible slip in the ribbon with smaller grains during deformation by X-ray diffractometry. Not like in bulk specimen, ε-martensite being very thin in the width of 10 ~ 20 nm and lots of stacking faults being inferred from streaks of SAD patterns, were revealed in melt-spun ribbons manufactured in the wheel speed of 50 m/sec.
Effect of Filling Powder Volume Rate in Wick Manufactured for Loop Heat Pipes
Authors: Wu Shen Chun , Huang Chuo Jeng , Gao Jhih Huang
Published: March 2012

This investigation studies the effect on pressure of the filling volume rate in a manufactured nickel powder capillary structure (wick) for a loop heat pipe (LHP). The filling volume ratio is an index of pressure from 1 to 1.3 to investigate the influence on filling weights of the internal parameters of a wick (permeability, effective pore radius and porosity) and heat transfer performance for LHP. The wick is manufactured, based on the standard and non-pressurized filling weights in the manufactured wick mold. The conversion of a pressure change to a weight change used to investigate the relationship between the change in filling volume of pressure to the internal parameters of the wick and the heat transfer performance. As the filling volume rate increases, the capacity of the wick increases, but an excessive filling volume rate makes the wick too dense, affecting its permeability and heat transfer performance in LHP. An experimental test demonstrates that the permeability and heat transfer performance are optimal at a filling volume ratio of 1.2.
Effect of Pre/Post Heat Treatment on the Friction Stir Welded SSM 356 Aluminum Alloys
Authors: Boonchouytan Worapong , Ratanawilai Thanate , Muangjunburee Prapas
Published: March 2012

The butt joints of semi solid 356 were produced in as cast conditions by friction stir welding process (FSW). This experiment studied in pre/post heat treatment (T6) using the welding speed 160 mm / min with tilt angle tool at 3 degree and straight cylindrical tool pin. The factors of welding were rotating speed rates at 1320, 1750 rpm and heat treatment conditions. They were divided into (1) As welded (AW) joints, (2) T6 Weld (TW) joints, (3) Weld T6 (WT) joints, (4) T6 Weld T6 (TWT) joints, (5) Solution treated Weld Artificially aged (SWA) joints and (6) Weld Artificially aged (WA) joints. Rotating speed and heat treatment (T6) condition were an important factor to micro, macro structure of metal and mechanical properties of the weld. Increasing rotating speed and different heat treatment condition impacted onto tensile strength due to the defects on joints. Therefore the optimum welding parameter on joint was a rotating speed 1320 rpm, the welding speed 160 mm/min, heat treatment condition of Weld T6 (WT) which obtained the highest tensile strength 228.92 MPa, as well as, highest hardness of 98.1 HV
Effect of Part Size on Surface Heat Flux during Immersion Quenching
Authors: Babu K.
Published: March 2012

In this paper, the effect of quench probe diameter on the heat transfer rate during immersion quenching of stainless steel (SS) probes in still water has bee studied. Quench probes of different diameters with an aspect ratio of 2.5 were prepared from SS. These probes were heated to 850 °C and then quenched in water. Time-temperature data were recorded during quenching. The surface heat flux and temperature were estimated based on the inverse heat conduction (IHC) method. The results of the computation showed that the different cooling regimes during quenching in water were significantly affected by the diameter of the quench probes. The peak heat flux was higher for the probe having larger diameter followed by the next larger diameter probes.
Preliminary Study on Cutting Solid Object Using Water at Pressure Exceeding 1000 MPa
Authors: Hilmi Ahmad Humaizi , Mohamad Nor Norazman , Ismail Ariffin , Alias Mohamed Yusof , Zhao Zi Jun , Abdullah Shohaimi
Published: March 2012

To date, the highest pump pressure available in market is 648 MPa from FLOW International Corp. Cutting with ultra high pressure reduces abrasive usage, faster cutting speed, increased depth of cuts and increase efficiency. This research explores the possibility of applying pressure exceeding 1000 MPa to push pure water to cut solid objects. 10 grams of PE4 explosives are exploded in a confined chamber with a rectangular opening. Simulations in designing the blast test jig are discussed. Simulations are done using Autodyn software. The simulation aims to get the optimum geometry that can give the highest pressure at nozzle exit. Two materials are chosen to cut; stainless steel 304 and aluminum 1100. Simulations show the optimum blast test jig can cut aluminum and stainless steel at certain thickness.
Synthesis, Characterization and Investigation of the Third Order Nonlinear Optical Properties of Pyrrole Schiff Bases
Authors: Velmathi Sivan , Reena Vijayaraghavan
Published: March 2012

We have investigated the third order nonlinear optical properties of pyrrole Schiff bases synthesized by condensing pyrrole-2-carboxaldehyde with two different diamines. The nonlinear optical measurements were performed using the nano- second laser pulses at 532nm wavelengthby employing the Z-scan technique. The Z- scan spectra reveal a large negative non-linear refraction co-efficient .The nonlinear refractive index was found to be of the order of 10 -14cm2/W and the magnitude of third order susceptibility was of the order of 10 -13esu. These compounds exhibit good optical power limiting property under nano-second regime and TPA (Two Photon Absorption) is the dominating process leading to the non-linear behavior.
Investigating the Effects of Powder Mixed Electrical Discharge Machining on the Surface Quality of γ–TiAl Intermetallic
Authors: Jabbaripour B. , Sadeghi M.H. , Shabgard Mohammad Reza , Shajari S. , Hassanpour H.
Published: March 2012

Due to outstanding properties of γ–TiAl intermetallic such as high resistance against fatigue, oxidation, corrosion, creep, dynamic vibration, high working temperature and also its application in aerospace, automotive industry and turbojet engines; in this paper, powder mixed electrical discharge machining (PMEDM) of γ–TiAl intermetallic by means of different additive powders including aluminum (Al), graphite (Gr), silicon carbide (SiC), chrome (Cr) and iron (Fe) is investigated to compare the output characteristic of surface quality and roughness. The results indicate that aluminum powder produces the best surface finish, followed by silicon carbide, graphite, chrome and iron respectively. The experimental results show that in the determined settings of input machining parameters, aluminum powder can improve the surface roughness of TiAl sample about 32%.
Surface Cleaning of 4H-SiC Using Hydrogen Plasma
Authors: Wang Hai Bo , Wang Xiao Bei , Zhang Xiao Ping
Published: March 2012

In order to improve the channel elecron mobility and decrease the surface roughness of SiC ,we have cleaned the SiC surfacre by hydrogen plasma with ECR–PEMOCVD plasma system. The surfaces were investigated by RHEED and X-ray Photoelectron Spectroscopy before and after hydrogen plasma cleanging. It indicated that the Si oxide content of SiC surface cleaned by hydrogen plasma for 18minutes is significantly higher than for 12 minutes and the SiC surface cleaned for 12 minutes at 200°C with ECR–PEMOCVD plasma system is the most smooth. The hydrogen plasma cleaning technology is very useful to improve the channel elecron mobility of MOS device.
Supply Chain Risk Prioritization Using a Hybrid MCDM Approach
Authors: Prasanna Venkatesan S. , Kumanan Somasundaram
Published: March 2012

In recent years, supply chains have become increasingly vulnerable to risks resulting in poor financial performance and customer service. Managing the supply chain risks is a challenging task. Resilience and responsiveness based strategies are being attempted to build a robust supply chain. To select the appropriate mitigation strategies, supply chain risks are to be prioritized. Supply chain risk prioritization is a Multi Criteria Decision Making (MCDM) problem. MCDM models for supply chain risk prioritization needs attention. In this research, a hybrid Analytic Hierarch Process (AHP) and Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) approach is proposed for supply chain risk prioritization. A case example of a typical tractor industry is presented to illustrate the performance of the proposed approach.
A Node Mobile Handoff Model Based on Resource Allocation in Wireless Mobile Networks
Authors: Dong Zan Qiang , Shen Su Bin
Published: March 2012

The technology on network interconnection handoff with the QoS guarantee is becoming an important research issue in wireless mobile networks. Most of the current researches focus on the cell mobile networks, the schemes of which are comparatively complex in solving the QoS guarantee in mobile node handoff and the utilization rate of resource is lower. In order to reduce these disadvantages to the minimal extent, the model (HDBRA) on the mobile node handoff with service guarantee applied in the wireless mobile networks is presented in the paper based on the dynamic network bandwidth resource allocation in the real-time detection on the data flow state and network traffic-load in interconnection gateway nodes. And according to the state of the applications data in mobile node handoff, the model describes and analyzes in detail the dynamic resource allocation and reservation, and the release of the reserved resource as well. In the scheme, the real-time adjustment on resource allocation is achieved based on the real-time measurement on network traffic-load in interconnection gateway nodes and the method also achieves the balance on network traffic-load. Theoretic analysis and simulation test the correctness and validity of the model in the paper.
Thermal Oxidation of NiAl-Al2O3 Coated on Mild Carbon Steel
Authors: Ramdan Raden Dadan , Prawara Budi , Suratman Rochim
Published: March 2012

Thermal oxidation is believed as an important phenomenon that naturally occurs on material subjected to elevated temperature such as NiAl-Al2O3 coated material. In the present study, thermal oxidation on this coated layer was prepared by heating processes of NiAl-Al2O3 coated on mild carbon steel. Deposition of NiAl-Al2O3 was performed by high-velocity oxy fuel (HVOF) process, whereas subsequent heating processes were performed at 3 different temperatures 600oC, 800oC and 1000oC. After the process, the effects of this thermal oxidation process on the phases formation, microstructure and qualitative toughness of thermally sprayed NiAl-Al2O3 coating were investigated. The results showed that significant amount of NiAl-Al2O3 phase was transformed into NiO phase by heating process at temperature higher than 800°C. In addition, decreasing of thickness of the coating layer was also found as the service temperature increases from 800 to 1000oC. Increasing of hardness was also observed as the heating temperature increases, which is predicted due to the formation of excessive oxide on the coating layer that in turn might impart the toughness of this layer. These conditions suggested that a careful determination of service temperature have to be taken in order to avoid excessive oxidation of the coating layer.
Optimization of Rare Earth Dope on MAl2O4 (M = Ba, Sr) by Self-Propagating High Temperature Synthesis
Authors: Sathaporn Taschaporn , Sutham Niyomwas
Published: March 2012

The Eu2+ doped barium aluminate (BaAl2O4:Eu2+) and strontium aluminate (SrAl2O4:Eu2+) with high brightness were synthesized by self-propagating high temperature synthesis (SHS) method. The influence of doping rare earth ions (Eu2+) on the luminescence of MAl2O4:Eu2+ were described in this study. The reactions were carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The morphologies and the phase structures of the products have been characterized by X-ray diffraction (XRD) and scanning electron microscope technique (SEM). The emission spectra of the products have been measured by an Ocean optics spectrometer at room temperature. Broad band UV excited luminescence was observed for BaAl2O4:Eu2+ and SrAl2O4:Eu2+ in the green region peak at λmax = 501 nm and 523 nm, respectively. The optimum Eu2+ doping ratio were 10.5 mol% and 6 mol% for BaAl2O4:Eu2+ and SrAl2O4:Eu2+, respectively
Compositional and Deposition Rate Dependence upon RF Substrate Bias of RF Sputtered Ni-Fe Films
Authors: Akhtar Pervez , Mahmud Riaz
Published: March 2012

82% Ni-Fe films have been prepared using Radio frequency (R.F) sputtered, R.F induced substrate bias. The results presented are of study of sputter films deposition at various RF substrate bias conditions so that suitable sputtering rate with optimum (target) composition could be determined for magnetoresistive sensing applications. Films have been sputtered with substrate temperature of 200° C, sputter gas (argon) pressure of 10mTorr with film thicknesses near 1000 °A. Substrate bias potential in the range 0 V to -400 V is varied in order to determine its dependence upon film composition and deposition rate. The result presented indicates the strong bias dependence upon film composition and deposition rate with most useful films for the application in concern could be produced at substrate bias potential in the range of -80 V to -120 V.
Effect of Tool Wear on Tri-Phase CVD Coated Carbide Tools Life while Turning Al6061
Authors: Davoudinejad Ali , Ashrafi Sina Alizadeh , Niazi Abdolkarim
Published: March 2012

Aluminum 6061 is a common alloy which is widely used in aerospace and yacht construction industry. Generally machining of aluminum alloys inherently generates high chip sticking on tool face and changes the tool edge geometry, which not only reduces tool life but also impairs the product surface quality. This study investigated the tool life and tool wear mechanisms besides evaluating surface roughness in various cutting conditions to attain finest possible surface with minimum tool wear. Turning experiments performed under dry orthogonal cutting of Al6061 using carbide CVD tri-phase coated inserts with constant depth of cut, various cutting speeds and feed rates. Insert’s flank and rake faces analyzed to assess wear mechanisms. Additionally Scanning electron microscope (SEM) employed to clarify different types of wear. Surface integrity and effect of built up edge in deviating surface roughness were studied in each cutting condition. Additionally results of experiments demonstrated that built up edge took over cutting edge and with sacrificing surface roughness, tool life increased by decreasing pace of abrasive wear propagation on flank face. According to these experiments the main reasons of flank wear were abrasive and adhesion of aluminum on tool face.
Effect of CaF2 in Precursors on Steel Pipe Lined Fe-Al Intermetallic-TiB2-Al2O3 Composite Coating by Centrifugal-SHS Process
Authors: Kerdkool Pajaree , Sutham Niyomwas
Published: March 2012

Steel pipe lined Fe-Al intermetallic-TiB2-Al2O3 composite were prepared by centrifugal-self-propagating high temperature synthesis (centrifugal-SHS) process from FeTiO3, B2O3, Fe2O3, Al and CaF2 as raw materials. The standard Gibbs energy minimization method was used to calculate the equilibrium compositions of the reacting species. The effect of adding CaF2 to the precursors on the result product were investigated. The phase separation between less porosity Fe-Al intermetallics-TiB2 with Al2O3 layer were affected greatly by adding CaF2. The phase compositions and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) couple with energy dispersive X-ray (EDX), respectively.
Effects of Phthalocyanine Blue and Ultramarine Blue Pigments on Nucleation of Polypropylene
Authors: Saravari Onusa , Keeratichiraththitikan Kodchagorn , Kerddonfag Noppadon , Chinsirikul Wannee
Published: March 2012

This study investigated the effect of the organic phthalocyanine blue and inorganic ultramarine blue pigments on nucleation of polypropylene (PP). The PP/pigment pellets containing various concentrations of each pigment (0.0001-0.1 wt %) were prepared by a melt blending process using a single-screw extruder, followed by fabricating into thin sheets using a single-screw plastic sheet extruder. The nucleation effects of both pigments were characterized by wide angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The WAXD patterns revealed that the addition of phthalocyanine blue or ultramarine blue did not affect the crystal structure of PP. The DSC results indicated that both pigments were able to nucleate PP, where the organic phthalocyanine blue pigment was a very efficient nucleating agent, increasing the crystallization temperature of PP by 15oC. The results of tensile and optical tests showed that the tensile strength and clarity of PP were improved with phathalocyanine blue addition.
Synthesis of Composite Materials from Natural Precursors by Self-Propagating High Temperature Synthesis Process
Authors: Sutham Niyomwas
Published: March 2012

The composite materials have been synthesized in situ by self-propagating high temperature synthesis (SHS) from natural precursors. The studied natural resources are ilmenite, kaolin, sand and rice husk ash. The reactions were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium compositions of the reacting species. The composites results have been characterized by scanning electron microscope (SEM), image analysis and X-ray diffraction (XRD). The results showed that the production of composite materials using SHS process is feasible and agree well with the thermodynamics calculations.
Effect of Wood Flour Content and Cooling Rate on Properties of Rubberwood Flour/Recycled Polypropylene Composites
Authors: Homkhiew C. , Ratanawilai T. , Thongruang W.
Published: March 2012

The present article summarizes an experimental study on the mechanical and thermal behavior of recycled polypropylene composites reinforced with rubberwood flour. Different compositions were varied to investigate mechanical strengths, melting temperature, storage modulus, and loss modulus. It was observed that the tensile and flexural strengths decreased with the increase of wood flour content. Furthermore, the air cooled composites showed improved properties in comparison with the water cooled composites. The melting and crystallization temperature results presented a weak influence of increased wood flour content on composites. However, dynamic mechanical thermal analysis showed an increase in the storage and loss modulus.
Low Velocity Impact Resistance of Hybrid Woven Glass Fiber-Carbon Fiber/Vinyl Ester Composite Laminates
Authors: Khan Zafarullah
Published: March 2012

In recent years, for the purpose of achieving enhanced mechanical properties of fiber reinforced composites, hybridized composites containing a combination of two or more types of fiber reinforcements have been explored. Perhaps the main parameter which controls the mechanical properties of the hybrid composites is the flexibility to arrange the hybrid fiber reinforcement layers in a variety of ways within the hybrid laminate. In this study, low velocity drop weight impact resistance of plain weave woven glass and carbon hybrid composites has been investigated. The study explores the effects of intra-ply arrangement sequence on the impact resistance of 24 and 32 ply laminates in which glass and the carbon plies have been differently stacked. The results show that impact resistance of woven glass fiber composites can be enhanced by hybridizing woven glass fabrics with woven carbon fabrics. The results indicate that the impact resistance is a function of the positions of the glass and carbon layers in the hybridized inter ply laminates.
Effect of Volumetric Fiber Fraction on Failure Strength of Thin-Walled GFRP Composite Cylindrical Shell Externally Pressurized
Authors: Gohery Scott , Golshan Abolfazl , Firouzabadi Farzin , Hosseininezhad Navid
Published: March 2012

Externally pressurized thin-walled GFRP composite cylindrical shell strength was studied against failure. Fiber breakage, matrix breakage, interlaminate shear deformation, delamination shear deformation and micro buckling failure were investigated employing maximum failure criteria as volumetric fiber fraction factor varied. One-ply cylindrical shell with fiber angle orientation of 0 degree was modeled in ABAQUS finite element simulation and the result was varied using analytical approaches. Moreover, the pressure fluctuations for various volumetric fiber fraction factors were quadratic according to plotted graphs obtained. Meanwhile, MATLAB software was used for theoretical analysis. The comparison of two approaches was proved to be accurate. Subsequently, failure strength of various laminated GFRP cylindrical shell with different fiber angle orientations at each ply was studied for diverse volumetric fiber fraction factors. Stacking sequence, fiber angle orientations were mainly effective on failure strength.
Mechanical Behavior of GFRP Laminated Composite Pipe Subjected to Uniform Radial Patch Load
Authors: Teshnizi S.H. Sharifi , Koloor S.S.R. , Sharifishourabi G. , Ayob Amran , Yazid Yahya Mohd
Published: March 2012

Cylindrical vessels are widely used for storage and transportation of fluids. Using composites shells can improve the corrosion resistance of the product and reduce weight therefore investigation of the mechanical behavior is important. For this purpose cylinders with 6, 12 and18-ply of GFRP , with symmetric ply sequence of [90/0/90]s, [90/0/90/0/90/0]s and, [90/0/90/0/90/0/90 /0/90]s with layer thickness 1.3 mm and mean radius 250 mm, are considered under uniform radial patch load. The analysis was based on the shell theory and classical mechanics of laminated composites. A code was written using MATLAB software to compute stress and deflection of the cylinder shell. In numerical simulation, each unidirectional composite ply is treated as an equivalent elastic and orthotropic panel. Analysis is focused on the area of cylinder where the patch load is applied. The results show that the analytical prediction compares well with numerical responses of previous literature. The procedure can be used to predict maximum stress and displacement in a multi-layer shell for various types of similar loading.
Mode I Interlaminar Fracture Characterization of CFRP Composite Laminates
Authors: Koloor S.S.R. , Hussin H. , Tamin M.N.
Published: March 2012

This study examines the deformation response of CFRP composites with preexisting delamination crack under Mode I loading. A DCB specimen is used in a series of Mode I interlaminar tests, each having a different initial delamination crack length. The 48-ply composite laminate has a symmetric ply sequence with 0/0 fiber orientation at the mid-plane. Apparent toughness is indicated by the composite specimen with a starter film insert, likely due to the presence of a neat pocket of resin at the front of the starter crack. The compliance of pre-delamination cracked specimens increases faster beyond the normalized delamination length, a/L of 0.68 due to effects of severe deflection of the longer DCB specimen arm. The critical energy release rate, GIC = 0.5 N/mm is determined based on pre-cracked DCB specimens. Fractographic analysis revealed a smooth fracture plane that indicates interface delamination as the primary failure mode.
The Effect of Molar Ratio of TiO2/WO3 Nanocomposites on Visible Light Prepared by Hydrothermal Method
Authors: Chainarong Siriphan , Sutham Niyomwas , Sikong Lek , Pavasupree Sorapong
Published: March 2012

The coupled TiO2/WO3 nanocomposites were synthesized by hydrothermal method by using hydrogen titanate and ammonium metatungstate hydrate as the precursors of TiO2 and WO3, respectively. The effects of hydrothermal conditions to prepare hydrogen titanate powders were studied. It was found that the hydrothermal condition at 130 °C for 24h shown the best result. The TiO2/WO3 nanocomposites were carried out as a function of varied molar ratio of TiO2/WO3 for 1:1, 3:1 and 1:3. The coupled TiO2/WO3 nanocomposites are characterized by transmission electron microscopy, UV-vis absorption spectra by UV–VIS spectrometer and photocatalytic activity by degradation of MB solution under visible light. The results show that the absorption spectra of the coupled TiO2/WO3 nanocomposites can be seen in visible light region which higher than pure TiO2 (from hydrothermal method) and P25-Degussa.
Application of VAM to Manufacturing Scheduling Problems
Authors: Sapkal Sagar U. , Laha Dipak
Published: March 2012

No-wait flow shop scheduling is a type of manufacturing scheduling which finds applications in advanced manufacturing systems and falls under the category of NP-hard combinatorial optimization problem. Heuristic methods are found to be the most suitable ones for obtaining solutions to these problems. We propose a heuristic method based on Vogel’s Approximation Method for developing the solution for the objective of minimizing total flow time in no-wait flow shop. The computational results are compared with the results of the well known existing heuristics in no-wait flow shop for minimizing the total flow time criterion. The results reveal that the proposed method significantly outperforms the existing heuristics, with comparable computational time. Statistical tests are used to validate the performance of the proposed method.
Study on Thermal Stability of Nano-Silica Thermal Insulating Composites
Authors: Feng Jin Peng , Chen De Ping , Ni Wen , Ma Shao Jian
Published: March 2012

This work investigated the thermal stability of nano-silica thermal insulating composites, which consisted of fumed silica, fibers and opacifiers. The volume shrinkage was introduced as an evaluation index to characterize thermal stability of the composites at different temperatures. The effects of serving temperature, serving time, particle size of fumed silica and mass ratio of SiC were discussed. The results indicated nano-silica thermal insulating composites have excellent thermal stability under the temperature of 800°C. The volume shrinkage was correlated positively with serving time. High specific surface area of fumed silica could bring good thermal insulating performance, but at the same time caused high volume shrinkage when applied at high temperatures. SiC as an opacifier has little influence on volume shrinkage, but too much amount may yet increase solid heat transfer and lead to the drop of thermal insulating properties.