bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Rolling on Microstructure and Room Temperature Tensile Properties of Newly Developed Mg-4Li-1Ca Alloy
Authors: Nene Saurabh , Kashyap Bhagwati Prasad , Prabhu Nityanand , Al-Samman T. , Estrin Yuri
Published: May 2014

Mg-30Ca and Mg-14Li (wt %) master alloys were melted successively in the induction furnace to obtain a Mg-Li-Ca ternary alloy containing 3.99 % Li and 1 % Ca. The as-cast material of thickness 4 mm was homogenised at 350° C for 120 mins and subsequently rolled to 62.5 % reduction in thickness at 300 °C to get 1.5 mm thick sheet. The microstructures of hot rolled samples were examined in as-rolled condition as well as after annealing at 350° C for various lengths of time. The presence of deformation twins was clearly seen in the as-rolled structure, whereas equiaxed twin-free grains were observed in the annealed condition. The average grain size was found to increase from 10 μm to 18 μm by annealing, according to the kinetics that follows a parabolic law. Tensile samples taken from rolled plate were deformed to failure at room temperature and a strain rate of 10-4 s-1. Ultimate tensile strength of as-rolled material increased to 213 MPa, while tensile elongation dropped to 6.5 % from the initial values of 134 MPa and 8.5 %, respectively. Annealing after rolling offered a good compromise between the enhanced tensile strength (160 MPa) and tensile ductility (9 %) suggesting viability of the proposed thermomechanical treatment as a means for enhancing both strength and ductility of Mg-4Li-1Ca alloy.
Influence of Low Cu Addition on Quench Sensitivity in Al-Mg-Si Alloys
Authors: Saito Takeshi , Marioara Calin D. , Røyset Jostein , Holmestad Randi
Published: May 2014

Quench sensitivity in two Al-Mg-Si alloys, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes, has been investigated using transmission electron microscopy (TEM) and corresponding material hardness. A two stage hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. However maximum hardness was not influenced by cooling rate, which could be related to higher precipitate number densities and volume fractions. Both alloys were over-aged faster in the slow cooling conditions.
Characteristic Features of the C-Type Orbital-Ordered State in the Simple Perovskite Manganite Sr1-xNdxMnO3
Authors: Sato Hiroki , Inoue Yasuhide , Koyama Yasumasa
Published: May 2014

In the highly-correlated electronic system Sr1-xNdxMnO3, the C-type orbital-ordered (COO) state is present for 0.15<x<0.38, and its crystal structure with the tetragonal-I4/mcm symmetry involves both the R25-type rotational displacement of MnO6 octahedra and the Jahn-Teller distortion as a response of a lattice system to orbital ordering. To understand the details of the competition between the rotational displacement and the Jahn-Teller distortion, the formation of the COO state from the disordered cubic (DC) state with the space group Pm3m has been investigated mainly by transmission electron microscopy. It was found that, when the temperature was lowered from the DC state for x = 0.20, for instance, COO regions with the tetragonal symmetry, exhibiting a {110}DC banded structure, were locally formed in the matrix below about 330 K. The subsequent aging at 300 K resulted in the growth of COO regions; that is, the time-relaxation phenomenon. Because of the presence of antiphase boundaries for the rotational displacement in the matrix, the crystal structure of the matrix should also have the tetragonal symmetry. In other words, it is understood that the coexistence state appearing just after cooling from the DC state consists of two tetragonal regions with different c/a values. The coexistence state is apparently characteristic of the competition between the rotational displacement and the Jahn-Teller distortion for the formation of the COO state.
Effect of Uniaxial Compressive Stress during Formation of Porous Aluminum by Mechanochemical Reaction on its Mechanical Properties
Authors: Sawamoto K. , Nakayama Noboru
Published: May 2014

Porous Al is a lightweight material with excellent heat insulation and sound absorption properties and is expected to be used in a wide range of applications. A method based on mechanochemical reactions has been developed as an environmentally friendly approach to porous Al production. Pure Al powder reacts with pure water to form a coating layer of Al (OH)3 on the surface of the powder particles. Adjacent particles then bind together by adhesion of their coating layers. Since a large number of voids remain between the individual particles, the compact is classified as porous Al. In the present study, a mixture of pure Al powder and pure water was subjected to uniaxial compressive stresses ranging from 0 to 100 MPa to form porous Al. The mechanical properties of the resulting compact were evaluated in terms of the amount of H2 produced, the density, the Al (OH)3 texture, the amount of Al (OH)3 formed, and the results of subsequent compression tests. The density of the porous Al was found to increase with increasing compressive stress during formation. The largest amounts of H2 (800 ml) were produced under a compressive stress of 10 MPa. As the compressive stress was increased, the total amount of generated Al (OH)3 increased, was approximately constant from 30 to 50 MPa, and then decreased. The initial maximum stress, the plateau stress, and the absorbed energy increased with increasing compressive stress and were 100 MPa, 17.5 MPa, and 10.1 MJ/m3, respectively, for a compressive stress of 100 MPa.
Microstructure and Residual Stress Formation during Friction-Stir Welding of Semi-Solid Cast ZK60-RE Magnesium Alloy
Authors: Silva E.P. , Batista Larissa Fernandes , Callegari Bruna , Pereira Victor Ferrinho , Buzolin Ricardo Henrique , Coelho Rodrigo Santiago , Warchomicka Fernando Gustavo , Requena Guillermo C. , Ramirez Antonio José , Pinto Haroldo
Published: May 2014

In this work, we report on the friction stir weldability of a semi-solid cast ZK60 alloy modified with 1.5 wt% mischmetall in the lap-joint configuration using a 120WV4 steel tool with concave shoulder and conical pin. The coarser solidification microstructure in the semi-solid cast ZK60-1.5%RE alloy requires low strain rates and increased heat input to produce lap-joints without inner defects. This was achieved with 250 rpm tool rotation and 50 mm/min welding speed. Friction stir welding results in a very fine grained microstructure in the stir zone probably due to dynamic recrystallization. In the thermomechanically affected zones dynamic recrystallization seems to occur within the solute enriched intergranular zones. The distribution of longitudinal residual stresses exhibit stress maxima at both thermomechanically affected zones. A compression peak is observed at the retreating side, whereas a tensile stress maximum occurs at the advancing side.
Casting in the Semi-Solid State of ZK60 Magnesium Alloy Modified with Rare Earth Addition
Authors: Silva E.P. , Batista Larissa Fernandes , Callegari Bruna , Feierabend Ivan , Buzolin Ricardo Henrique , Coelho Rodrigo Santiago , Warchomicka Fernando Gustavo , Requena Guillermo C. , Pinto Haroldo
Published: May 2014

In this work, the casting process under mechanical agitation in the semi-solid state was investigated for the production of ZK60 magnesium alloy modified with the addition of 2.5% wt of mischmetal. The results show that this process enables the production of ingots with homogeneous chemical composition and free of shrinkage, inner defects and internal oxidation. The as-cast microstructure consists of an α-Mg matrix with globular grains reinforced by a grid of distinct intermetallics of Mg-Zn, Mg-Zn-RE and Mg-RE type along the grain boundaries. The yield strength at room temperature undergoes more than 50% increase during direct T5 aging, thus reaching 170 MPa. At 300°C, however, the dispersion of nanometric precipitates does not modify the hot deformation behavior of the aged alloy, which undergoes dynamic recrystallization in a similar manner to the as-cast alloy. DRX at 300°C is fastest for the alloy solution-treated at 500°C.
Simulation of Cu Precipitation in the Fe-Cu Binary System
Authors: Stechauner Georg , Kozeschnik Ernst
Published: May 2014

Cu precipitation in steel has been investigated numerous times. Still, a consistent simulation of the nucleation, growth and coarsening kinetics of Cu precipitates is lacking. Major reason for this is the fact that Cu precipitation involves complex physical interactions and mechanisms, which go beyond the classical precipitation models based on evaporation and absorption of precipitate-forming monomers (atoms). In the present work, we attempt a comprehensive modeling approach, incorporating coalescence results from Monte Carlo simulation, prediction of the nucleus composition based on the minimum energy barrier concept, diffusion enhancement from quenched-in vacancies, dislocation pipe diffusion, as well as the transformation sequence of Cu-precipitates from bcc-9R-fcc. Our simulations of number density, radius and phase fraction coincide well with experimental values. The results are consistent over a large temperature range, which is demonstrated in a TTP-plot.
Plastic Deformation and Elastic Properties of Ti-Nb-Zr-Ta(-Fe-Si) Biomedical Alloys
Authors: Stráský Josef , Janeček Miloš , Harcuba Petr , Landa Michal
Published: May 2014

Beta titanium alloys are promising biomedical material for their excellent biocompatibility and low elastic modulus. Moderate strength of those materials in beta-annealed condition can be increased by precipitation hardening of alpha phase, but this causes significant increase in elastic modulus. In this study, small additions of Fe and Si are used to increase strength of commercial Ti - 35Nb - 7Zr - 5Ta (TNZT) alloy. Alloys with iron content up to 2% and silicon content up to 1% were manufactured. Elastic properties were investigated by pulse-echo method and flow curves were determined from tensile tests. Modulus of elasticity is increases from initial 60 GPa to 80 GPa due to Fe and Si content. Strength and modulus of elasticity were then related to chemical composition. Yield stress is increased from 450 MPa to 700 MPa thanks to small Fe and Si additions. Fe causes solid solution strengthening exhibited by sharp yield point. (Ti,Zr)5Si3 intermetallic particles further increase strength via precipitation hardening. An alloy containing 0.5% Si and 2% Fe showed improved properties for biomedical use.
Dislocation Creep in Al-22.2, 53.6 and 101 at.ppm Fe Solid Solution Alloys
Authors: Takeshima K. , Uesugi Tokuteru , Takigawa Yorinobu , Higashi Kenji
Published: May 2014

Creep tests of ultra-high-purity (99.999%) Al and Al-22.2, 53.6, 101 at.ppm Fe solid solution alloys were conducted at 773 K in the stress range of 2-6 MPa in order to investigate effect of solute Fe on high temperature deformation of Al. Creep resistance was enhanced by addition of Fe in solid solution. The stress exponents of the samples exhibited values of about 5, which indicate that climb-controlled dislocation creep was dominant deformation mechanism. It could be suggested that Fe atoms segregating in dislocations due to the strong interaction between solute Fe atoms and the dislocation enhanced the creep resistance.
Elemental Clustering and Structure of Liquid LBE
Authors: Balijepalli Santosh , Kaciulis Saulius , Amati Matteo , Montanari Roberto , Varone Alessandra
Published: May 2014

Liquid Pb–Bi eutectic (LBE) alloy is of great interest as coolant and neutron spallation source for the accelerator driven systems (ADS).
Scanning Photoemission Microscopy (SPEM) at the ELETTRA synchrotron radiation facility of Trieste was carried out on samples quenched from melt at different temperatures. SPEM analyses show that the two components (Pb and Bi) are not homogeneously distributed in the range of temperature from melting up to 518 °C, in particular they form clusters enriched in Pb and Bi.
The cluster size decreases as temperature increases hence diffusion occurs between clusters and matrix leading to the progressive disgregation of clusters that is almost completed at 518 °C.
Such micro-chemical evolution is accompanied by a structural change of the liquid evidenced by the results of High-temperature X-ray Diffraction (HT-XRD). In particular, radial distribution function (RDF) curves show a progressive change of the ratio between the shell radii of 1st and 2nd nearest neighbours.
Modelling High Integrity Steel Forgings for Turbine Applications in the Power Generation Industry
Authors: Watson Christopher J. , Dean Trevor A. , Strangwood Martin , Davis Claire L.
Published: May 2014

The continuous drive toward higher operating efficiency, greater reliability and longer life of steam turbines has introduced a need for higher integrity components to operate at higher temperatures and pressures. This poses several material and processing challenges to ensure that the components have metallurgical stability and the required mechanical properties in the high temperature environment. Modelling the open-die press forging process, used to manufacture steam turbine discs from cast ingots, is complex due to the variation of strain, strain rate and temperature within the ingot. These variations mean that recrystallisation and grain growth do not occur uniformly throughout the ingot. Severe plastic deformation is used to promote recrystallisation in order to refine the grain size and improve strength and toughness properties. A major part of the modelling described in this paper involves prediction and validation of strain, strain rate and temperature distributions during open-die forging. A sensitivity study has confirmed the requirement for accurate thermal and physical data such as Interfacial Heat Transfer Coefficient (IHTC), work-piece emissivity, specific heat and friction coefficient. In this paper experimental determination of these data for the grade of heat resistant steel being modelled, over process parameter ranges appropriate to open-die forging operations, is described. Incorporation of these data into a finite element-based model for strain variation within an ingot is reported with consideration and measurement of dead zone for thermo-mechanical simulation trials.
Biodiesel B10 – An Alternative Fuel for Diesel Pick-Up Trucks
Authors: Suthisripok Tongchit , Ruechakiatdtikun Teerasak
Published: May 2014

From the test study of the use of biodiesel B10 in a diesel pick-up truck with an engine size not over 2500 cc, it showed that biodiesel B10 can be effectively used as an alternative fuel giving low polluted emission. On dynamometer performance test of the Isuzu TFR 2500 Di pick-up truck used over 200,000 kilometers, it resulted that the maximum power output from the use of diesel was 60.9 hp@3,630 rpm whereas from the use of biodiesel B10 was 58.1 hp@3,700 rpm which was about 4.6% lower. Considering the heating value of diesel of 35,970 kJ/l, it was 8.4% higher than that of the pure biodiesel (32,940 kJ/l). Since biodiesel B10 is a mixture of 10% pure biodiesel and 90% diesel fuel, and the molecular structure of biodiesel contains 11%wt oxygen gives better combustion. However, biodiesel was more viscous compared to diesel at the same fuel injection pressure of 180 kgf/cm2, therefore, the fuel nozzle injector was changed to a 5-hole nozzle from the original 4-hole nozzle for better fuel spray and atomization in the combustion chamber. The maximum power output of 58.6 hp@3,685 rpm was achieved but the fuel consumption rate and soot emission were lower. Comparing the road test results at the average speed of 90 km/h, the average consumption rate of biodiesel B10 was 16.4 km/l which was about 5.2% higher than that of diesel of 17.3 km/l. When changing to 5-hole fuel injector, the average consumption rate of biodiesel B10 was 18.4 km/l, about 12.2% saver than from the original 4-hole nozzle use. Similarly the average consumption rate of diesel when using the 5-hole nozzle injector was saver to 18.6 km/l. It clearly provided better fuel atomization in the combustion chamber. From the random emission measurements, it showed that there was 33.7% soot from using biodiesel B10 which was lower than the use of diesel of 34.2% for 4-hole fuel injector, and decreased to 31.2% when switching to the 5-hole fuel injector. Keywords: biodiesel, B10, alternative fuel, diesel pick-up truck, fuel nozzle injector
Combustion of Municipal Solid Waste in a Pilot Scale Fluidized Bed Combustor
Authors: Johari Anwar , Mat Ramli , Kamaruddin Mohd Johari , Tuan Abdullah Tuan Amran , Sulaiman Wan Rosli Wan , Ali Asmadi
Published: May 2014

Combustion study of municipal solid waste combustion in a pilot scale fluidized bed combustor had been carried out. The work was aimed at demonstrating sustainable combustion of municipal solid waste by employing operating parameters gained from previous studies. The primary and secondary air factor used were AF = 0.8 and AF = 0.6 respectively. The fluidization number was 5Umf and both in-bed and freeboard region temperature distributions were monitored continuously. Results on the combustion studies revealed that the initial bed temperature could be sustained due to high thermal capacity of sand but later dropped due to problem related to the mixing of bulky and heterogeneous components of municipal solid waste and sand.
Additional Gas Resource for Coal Bed Methane by Applying Underground Coal Gasification and Enhanced Coal Bed Methane
Authors: Sulaiman Wan Rosli Wan , Azizan Norlia , Jaafar Mohd Zaidi , Ismail Abdul Razak , Hamid Mariani Abdul , Johari Anwar , Mat Ramli , Kamaruddin Mohd Johari , Ali Asmadi
Published: May 2014

Methane gas obtained from coal sources can be classified into two categories i.e Coal Bed Methane (CBM) and Underground Coal Gasification (UCG) gases. The Industry today often neglects the importance of capturing the UCG as important source of methane potential besides the surface gasification potential. This research will evaluate on the new resource estimation of methane as reserves with application of new technological advances in exploitation. As an analysis, the UCG energy return is significantly higher than that of CBM. Both CBM and UCG output gas can be liquefied, or used as a direct feedstock to local power stations. The CO2 generated from UCG process may be used for Enhanced Coal Bed Methane (ECBM) process because of more adsorption capacity than methane, may lead to additional methane potential. Deeper coal seams may be targeted for CBM, followed by UCG for additional resources in the form of coal gas. A depleted CBM area may be targeted for UCG with some modification on the well profile. Developing an integrated and centrally controlled approach to exploit the coal resources in which, the appropriate extraction methodology should be identified for each particular target coal-seam or groups of coal seam. It is important to strategize the sequencing of energy extraction methods to provide an optimal balance between the energy delivery for sustainable future and its true socio-economic value. As from this analysis, with 245.6 acres of coal, estimated gas can be produced is 3.25 TSCF which is 101 BSCF is coming from CBM, 3.14 TSCF from UCG and another 14.45 BSCF is from ECBM.
Optimization of Base-Catalyzed Transesterification in Biodiesel Production from Refined Palm Oil via Circulation Process through Static Mixer Reactor
Authors: Niseng Suhdee , Somnuk Krit , Prateepchaikul Gumpon
Published: May 2014

In this work, response surface methodology (RSM), with 5-level and 2-factor central composite design (CCD) was used to optimize the condition of base-catalyzed transesterification from refined palm oil. The two main parameters; methanol concentration and potassium hydroxide concentration, were varied to investigate the effect on the methyl ester purity. The result indicated that the KOH concentration was the most significant to produce methyl ester (the lowest p-values occurs in all response models). From excel solver, full quadratic model was obtained for predicting the response surface models. The suitable condition: 23.81 vol.% methanol and 11.80 wt.% KOH under temperature of 60°C and reaction time of 60 min, is the optimum condition.
Spray Visualization of Biodiesel and Diesel in a High Pressure Chamber
Authors: Srichai Prathan , Chareonphonphanich Chinda , Karin Preechar , Chollacoop Nuwong
Published: May 2014

The present research attempted to characterize fuel spray pattern, such as spray angle, spray penetration and their mixture formation by recourse to images analysis. Diesel and biodiesel were used to investigate via a single hole injector (solinoild type) in a constant volume high-pressure chamber. In this experimental study, the spray characteristics of diesel and biodiesel fuel were comparatively evaluated. Initial conditions were ambient temperature, ambient density of 21 kg/m3, injection durations varied from 0.5 and 1 ms and rail pressure of 400 and 800 bar. The series of images were captured by high speed video camera with resolution of 7,500 frames per second and shutter speed of 1/10,000 sec under Schlieren photography technique. The result showed the biodiesel spray penetration was longer than that of the diesel, and spray angle of biodiesel in start injection was larger than biodiesel. From the results, it can be concluded that the higher the density and viscosity of biodiesel, the stronger the effect on the spray mixture formation.
Mixed-Mode [I/III] Fracture Simulation of Rubber
Authors: Permpipat Kiatisak , Jearanaisilawong Petch
Published: May 2014

The objective of this work is to develop fracture simulations of rubber undergoing a combined tensile and out-of-plane shear loading. Rubber sheets are tested under mode-I (opening mode), mode-III (tearing mode) and mixed-mode [I/II of fracture. The experiments are simulated in finite element software to evaluate the J-integral for each mode of deformation. Comparison between simulation and testing results are in good agreement. The simulations serve as test cases and evaluation tools for the development of mixed mode fracture criterion of rubber.
Successful Simulation of Airflow in the Microenvironment of an Assembly Automation Machine and its Implication
Authors: Thongsri Jatuporn , Khaokom Adisorn
Published: May 2014

Today, the hard disk drive (HDD) industry is using assembly automation machine (AAM) to construct head stack assembly (HSA) from smaller parts. AAM needs to operate in a clean environment with very low particle counts. To achieve this end, fan filter Unit (FFU) is used to supply purified air into the environment by filtering out airborne particles from recirculating air. In this study, we investigated numerically the airflow induced by FFUs inside a microenvironment that houses an AAM in an HDD factory. The boundary conditions chosen for simulation were directly derived from the real ambient conditions in this HDD factory. We found that the FFUs not only filter out airborne particles from the air supplied into the microenvironment but also act as a particle blocker, pushing away the nearby particles in the air surrounding the openings of the microenvironment. The findings from this study can be applied to cases where other kinds of machinery need to be protected from airborne particles.
The Study of Renewable Heat Incentive in Thailand
Authors: Limwittayakorn Teeramaethin , Wongsapai Wongkot
Published: May 2014

Renewable energy activities in Thailand are now continuously developed under the deployment of the nationals Alternative Energy Development Plan (AEDP). However, renewable for heat activities require financial instrument or scheme to support the long-run widespread development. This study aims to investigate the appropriate renewable heat incentive (RHI) to encourage the renewable heat projects in Thai market by calculate from the fuel switching concept from various fossil fuels to renewable energy and applying the investment cost, fuel cost, operation and maintenance cost, depreciation along with engineering approaches with expected rate of return from 10 to15%. The replacement from five fossil fuels to 11 types of potential renewable energy, in gasification and direct heating technology, we found that anthracite replaced by RDF require the most support with 5.14 baht per kilogram of RDF. However, in the case of fuel switching to the expensive fuels such as oil and LPG to renewable energy such as biomass, the incentive values are all negative, which means that no support required..
Design an Economy Cooling System for the Solar Panel
Authors: Phayom Warachit , Namahima Apichai
Published: May 2014

This study was for design an economy cooler for increasing energy conversion efficiency of solar panel. Acrylic plastic was used to be material of the cooler and water was a working fluid in the system. The cost to build the cooler model was around 400 Baht. The results found, using cooling system increased energy conversion efficiency and power generation, especially, water flow rate at 200 ccm. At 200 ccm of water flow rate, it increased 0.52% of energy conversion efficiency and 18.01% of power generation. Thus this flow rate was the best condition for increasing energy conversion efficiency. It might due to this flow rate was not slow and was not that fast to absorb heat from solar panel.
Design and Development the Pressure Chamber of the Continuous Belt Air-Blast Freezer in Freezing Shrimp Process
Authors: Phuekpan Kantinan , Tangchaichit Kiatfa
Published: May 2014

The air-blast freezer is common freezing technique for shrimps in seafood industry. In many
companies encounter with developing this technology for food industry. In this study, Development in effects and behavior of airflow over in pressure chamber of continuous belt air-blast freezer, were investigated by simulating the airflow field by using computational fluid dynamics (CFD). Pattern holes in plenum plate and Modifying shape tunnel were cases study in redesign of development. The average velocity at outlet holes of airflow were determined and the streamline and vector of airflow were analyzed. The effects of redesign could increase the average relative velocity at outlet up 22-
32% compared with the original design.
Numerical Simulation of Al2O3-Water Nanofluid Flow and Heat Transfer in a Tube with Angled Rings
Authors: Promvonge Pongjet , Sripattanapipat Somchai , Jedsadaratanachai Withada
Published: May 2014

A numerical investigation has been conducted to examine turbulent flow and heat transfer characteristics in a three-dimensional isothermal tube mounted with 60° angled rings (AR). The ARs with pitch spacing ratio, PR=1.0 and various blockage ratios (BR) ranging from 0.025-0.1 are introduced. The computations are based on a finite volume method and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds number (Re) ranging from 3000 to 12000. To generate a main counter-vortex pair flow in the tube, ARs at an attack angle of 60° are mounted repeatedly in the tube. Effect of different BRs at a single PR and nanofluid, Al2O3water, with volume fractions 1% and 5% on heat transfer and friction loss is investigated. It is apparent that two main vortex flows created by the ARs exist and help to induce impinging flows on the tube wall leading to drastic increase in heat transfer rate over the tube. The increment in the BR gives rise to the increase in the Nusselt number and friction factor. The computational results reveal that the maximum thermal enhancement factor for the AR with BR=0.025 is found to be 1.8 at Re =3000. The results show that nanofluid, Al2O3 water, can increase the thermal performance when increasing volume fraction to 5%.
Thermal Characteristics in a Tube Fitted with Inclined Vortex Rings
Authors: Koolnapadol Narin , Chingtuaythong Witoon , Promvonge Pongjet , Kwankaomeng Sutapat
Published: May 2014

The paper presents an experimental study on the heat transfer, pressure loss and thermal performance characteristics in a round tube fitted repeatedly with inclined vortex ring (VR) under a uniform wall heat flux. Periodically VRs are inserted into the tube with a view to generating vortex flows that assist to increase the heat transfer rate of the tube. The airflow rate in terms of Reynolds number is ranging from 5000 to 25,000. Measurements are carried out for the VR with a single blockage ratio, BR= e/D= 0.1 and an attack angle, α = 20o, at fourVR pitch ratios, PR=P/D= 0.5, 1.0, 1.5 and 2.0. The variations of heat transfer and pressure loss are presented in the form of mean Nusselt number and friction factor respectively. The experimental results show that the use of the VRs leads to the considerable increase in heat transfer and friction factor values in comparison with the smooth tube. The VRs at PR = 0.5 provides the highest heat transfer and friction factor.
Thermal Behaviors in a Square Duct with U-Ribbed Tape Inserts
Authors: Khanoknaiyakarn Chitakorn , Skullong Sompol , Promvonge Pongjet , Jayranaiwachira Nuthvipa
Published: May 2014

This paper presents an experimental study on thermal characteristics in a constant heat-fluxed square-duct heat exchanger with U-ribbed tape inserts. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4000 to 38,000. The insertion of the U-ribbed tape is performed with an axial rib-pitch set to four times duct-height (4H) at a single attack angle, α=45° and the ribbed tape is diagonally inserted in the square duct in order to generate longitudinal vortex flows. Effects of five blockage ratios (e/H=0.1, 0.15, 0.2, 0.25 and 0.3) on heat transfer and friction loss are experimentally investigated. The experimental result shows that the insertion of the U-ribbed tape at e/H=0.3 provides the highest heat transfer and friction factor values but the one at e/H=0.25 yields the highest thermal performance enhancement.
Heat Transfer Enhancement of Impinging Row Jets in Cross-Flow with Mounting Baffles on Surface
Authors: Pansang Rattanakorn , Wae-Hayee Makatar , Vessakosol Passakorn , Nuntadusit Chayut
Published: May 2014

The aim of this research is to enhance heat transfer on a surface of row of impinging jets in cross-flow by mounting some baffles on the surface. A row of 4 jets with inline arrangement discharging from round orifices impinged normally on inner surface of wind tunnel with simulated cross-flow. The orifice diameter (D) was 13.2 mm. The jet-to-surface distance and jet-to-jet distance were fixed at H=2D and S=3D, respectively. Four couples of baffles with V-shaped arrangement at attack angle, θ=30o, were mounted on surface in upstream or downstream of impinging jets and the location of baffles attachment is L=1.5D apart from the jet impingement region. The velocity ratios (Jet velocity/cross-flow velocity) were varied from VR=3, 5 and 7 while the jet velocity was kept constant corresponding to Re=13,400. The experimental investigation was carried out for heat transfer characteristic by using Thermochromic Liquid Crystal sheet, and heat transfer coefficient distributions were evaluated using an image processing method. The results show that the impinging jets with mounting the baffles in the upstream region of jet impingement region can enhance the heat transfer rate throughout VR.
Heat Transfer Enhancement of Impinging Jet from Pulse Jet Combustor
Authors: Narato Pathomporn , Maliwan Kittinan , Nuntadusit Chayut
Published: May 2014

The aims of this study are to investigate flow characteristics in pulse jet combustor and heat transfer characteristics of impinging jet from pulse jet combustor. The combustor is Helmholtz type which has single combustor chamber and single tailpipe. The inner diameter (D) of tailpipe was 47 mm and tailpipe length was about 16D. The effect of number of air inlets: single inlet, double inlets with 90o apart, double inlets with 180o apart and triple inlets with 90o apart on flow and heat transfer characteristics were studied. A water cooled heat flux sensor was applied to measure heat transfer rate on the surface at stagnation point. The jet-to-plate distance was varied at L=1D, 2D, 4D, 6D and 8D. Two of pressure transducers were mounted on the wall of combustion chamber and on the wall of tailpipe at 4D from tailpipe outlet to measure pressure simultaneously. It is found that the variation of pressure near the tailpipe outlet is strongly depended on air inlet configurations. The pressure variations in pulse jet combustor could be preliminary related to the temperature and velocity of jet from tailpipe and heat transfer rate on jet impingement surface.
Flow Pattern Map of Malaysian Crude Oil and Water Two-Phase Flow in a Pipe System
Authors: Ismail Issham , Misnan Shahir , Ismail Ahmad Shamsul Izwan , Mohsin Rahmat
Published: May 2014

Water produced along with the crude oil during production and transported together in a pipeline is a common occurrence in a petroleum production system. Understanding the behavior of crude oil-water flow in a pipe is crucial to engineering applications such as design and operation of flow lines and wells, and separation systems. Presently, there was no two phase flow study done on the Malaysian waxy crude oil-water. Therefore, a research work was conducted at the Malaysia Petroleum Resources Corporation Institute for Oil and Gas, Universiti Teknologi Malaysia to study the flow pattern of the Malaysian waxy crude oil-water flowing in a closed-loop system at the ambient condition through a 5.08 cm ID stainless steel horizontal pipeline. The research works comprised fluid characterization and flow pattern observation using a video camera camcorder. Five flow patterns have been identified, namely stratified wavy flow, stratified wavy with semi dispersed flow at interface and oil film, dispersion of water in oil and oil continuous with emulsion, dispersion of oil in water with water continuous, and the newly found semi dispersed flow with semi emulsion at interface and thin oil film. The experimental results could be used as a platform to understand better a more complex case of gas, oil, and water flow in a pipeline, which is of utmost importance in designing optimum surface facilities.
L10-CoPt Bit Patterned Media with Tilted Easy Axis for Ultrahigh Areal Density over 2.5 Tb/in2
Authors: Kaewrawang Arkom
Published: May 2014

Ultrahigh areal density is the key target of hard disk drive technology. Hence, writing field strength from head and switching field, Hsw, of media should be improved. In this work, we propose the one of alternative method to increase data density and reduce Hsw of the media by using tilted easy axis technology for bit patterned media (BPM) at areal density beyond 2.5 Tb/in2. Moreover, transition noise and superparamagnetic limit have been eliminated owing to characteristics of BPM. The effect of exchange coupled between adjacent bits, Adot, of tilted easy axis of BPM is analyzed by micromagnetic simulation software - the object oriented micromagnetic framework based on Landau-Lifshitz-Gilbert equation. The BPM with tilted easy axis perform clearly the reduction of Hsw below perpendicular media and available writing head field. The Adot of BPM has no effect on decreasing Hsw. Anisotropy and Zeeman energy density of BPM with tilted easy axis are higher and lower than perpendicular BPM, respectively. Thereby, BPM with tilted easy axis have high potentiality to improve Hsw of media at ultrahigh data density.
Microwave Assisted Magnetization Reversal on Exchange Coupled Composite Media
Authors: Wannawong Naruemon , Tipcharoen Warunee , Kaewrawang Arkom
Published: May 2014

To overcome superparamagnetic limit, microwave assisted magnetic recording (MAMR) is one interesting magnetic recording technology. Therefore, the effect of microwave on magnetization reversal in media should be analyzed. In this work, we propose the MAMR to decrease switching field (coercivity, Hsw) in exchange coupled composite (ECC) media by using the micromagnetic simulation based on the Landau - Lifshitz - Gilbert equation. The Hsw of single layer and ECC media without microwave field is 110.90 and 7.7 kOe, respectively. When the oscillating microwave field is added, Hsw of single layer media with microwave frequency of 2.5 - 40 GHz is lower than 110.90 kOe. Likewise, Hsw of ECC media with microwave frequency of 5 - 16 GHz is lower than 7.7 kOe and has the lowest value of 4.9 kOe at frequency of 10 GHz. The results from this work lead to solve superparamagnetic limit and increase areal density in hard disk drive.
Influence of Na Doping on the Thermoelectric Properties of CuAlO2 Delafossite
Authors: Wongcharoen Ngamnit , Gaewdang Thitinai
Published: May 2014

The polycrystalline Na-doped CuAlO2 ceramics were obtained by solid state reaction method. The mixture of high purity grade of CuO, Al2O3 and NaNO36H2O powders was ground and then pressed by using uniaxial pressure. The obtained pellet was sintered in air at 1,423 K for 24 h. XRD patterns showed the crystal structure of the as-sintered Cu1-xNaxAlO2 (0x0.05) belonging to rhombohedral, space groupalong with the CuO and CuAl2O4 phases. The minimum resistivity value around 4.48x102 Ωcm and maximum hole concentration around 2.04x1016 cm-3 were observed for x=0.03 at room temperature. The properties of Seebeck coefficient and electrical resistivity were measured in the high temperature ranging 300 to 700 K. The results of electrical resistivity, Seebeck coefficient and power factor values decrease with increasing Na content. The calculated activation energy of conductivity (in the range of 160-250 meV) is larger than that of thermopower (in the range of 26-83 meV) which suggests that the conduction mechanism may be determined as a small polaron hopping type.
Designing Decoupler and PID Controller for TITO System
Authors: Dolpullop Sasiprapa , Chitwong Sakreya
Published: May 2014

This paper describes the two inputs - two outputs control theory. The theory is using the simplify decoupler filter that can reduce the disturbance arising from loop interaction. The system controls both the pressure and flow rate in the closed tank. The media of the process is water. The work includes four important aspects: Designing, Implementation and Test. In this design consist of two parts such as models of the process and decoupler. In this simulation was used a MATLAB to finding a suitable decoupler. In this implementation was used a personal computer, Pressure Transmitter, Magnetic Flow Meter, DP/PA coupler, Convertered IF 303,FI303 and The controller of SIEMENS S7 400 Modules which all of implements was created to control systems by used the technology of PROFIBUS to create a networked control system(NCS). In this test was used to compare performance of the old TITO systems with the new TITO system.
Determination of Tensile Properties of Hemp-Fiber Bundle by Using Tensile Testing Equipment with Raspberry Pi
Authors: Limpitipanich Paiboon , Promwungkwa Anucha
Published: May 2014

Tensile strength of some natural fibers such as hemp is higher than that of steel. To determine tensile properties of hemp fiber, a fiber or bundle is tensile tested with universal testing machine that is controlled by personal computer. This paper presents a small tensile testing equipment that is controlled by Raspberry Pi (RPi), a credit-card-sized single-board computer. General Purpose Input Output (GPIO) pins on RPi were used for controlling the machine crosshead and receiving the tensile load that apply to a hemp bundle. A stepper motor was used to drive the crosshead. Tensile load was measured by using a load measurement system included load-cell, instrument amplifier, and analog-to-digital converter. The applied load and extension were real-time displayed and continuously recorded throughout the test. Testing hemp-fiber bundles with the proposed equipment found that their tensile strength and Youngs modulus were 446.75±184.36 MPa and 18.23±8.26 GPa, respectively. These results were in good agreement with the properties founded in other publications. Test results also found that hemp-fiber bundle with smaller diameter showed higher tensile strength than that of larger one.
Design and Control of One Degree of Freedom Haptic Interface System with PID Controller
Authors: Pothi Nattachai
Published: May 2014

This paper presents a design of a one-degree-of-freedom haptic interface system with an aim to investigate control of the system. The system comprised master devices, a system interacting with a user, and slave devices, a system interacting with environments. Both sets of devices were coupled with a gripper, which was designed in a shape of a cantilever beam, to measure force, and a DC motor was employed to drive precision ball screws, which were attached to the gripper, so as to create linear motion. In addition, an encoder was installed so as to investigate motion of the gripper, and the analysis results were employed for a design of a controller, based on the P, PI, PD, and PID type. The aim of this is to provide an operator with tactile sensing through control of the master devices while the slave devices were in contact with an object. The simulation results showed that the stiffness of an object affects stability of the system with a designed controller, causing, limitation of operation, that is, the system was stable when stiffness of the object was less than 43.3 kN/m, and the operator obtained a good response of positions and resistance while contacting with an object as though the operator has direct interaction with such an object.
Thai Handwriting Practice on Android Tablets
Authors: Damkliang Kasikrit , Nanphan Pakkaton , Mamodee Tanida
Published: May 2014

This paper describes the design, implementation, testing, and evaluation of a Thai handwriting practice application for pre-primary school students, aged 4 to 6 years old, aimed at Android tablets. The application provides mechanisms for alphabet validation, score calculation, and handwriting tutorial animations.
Personal Health Assistant on Android Mobile Device: Sleeping, Nutrition and Exercise
Authors: Anusornpakdee Kiatateeti , Limpanadusadee Matugorn , Vasupongayya Sangsuree , Kamolphiwong Sinchai
Published: May 2014

Good health can be achieved by maintaining good behaviors such as a good night sleep, enough exercise and good nutrition. However, the competitive environment nowadays prevents such good behaviors. Thus, this work aims to develop an application on mobile devices that is able to (1) record the daily sleeping, exercise and nutrition information, (2) analyze the collected information in order to provide a notification or an alarm, and (3) present the analyzed results in a simple and easy to understand format. The proposed application can collect data from other application and from the users. A set of simple data analysis methods is performed on the collected data in order to provide a personal health advice based on the user pre-defined preferences.
Automatic Genre Classification of TV Programs Using Audio and Face Processing
Authors: Doungmala Pathasu , Meesomboon Anupap
Published: May 2014

In this paper we present a new system to classify TV programs into predefined categories based on the analysis of their audio and video contents. This is very useful in intelligent display and storage systems that can select channels and record or skip contents according to the consumer's preference. Distinguishable patterns exist in different categories of TV programs in terms of human faces and audio. In this paper four categories divided into news, cartoon, variety and sport are of interest. News and variety have differences between frames less than sport and cartoon. For audio feature, we apply short time energy, zero crossing, spectral centroid and short time Fourier transform for feature extraction. For face feature, in the first step, Haar like feature is employed for face detection and eigenface is then applied for feature extraction. Then, neural network is implemented for classification. From experimental results, classification rate of 95% accuracy which is better than the other paper is achievable.
Thai Face Cartoon Detection and Recognition Using Eigenface Model
Authors: Jirawatanakul Yardnapa , Watanapa Saowaluk
Published: May 2014

In this paper, an effective method for Thai face cartoon detection and recognition is used based on haar like feature and eigenface model. The basic idea of this method is to detection and recognition a cartoon Thai from the database based on a cartoon drawn by an artist. This method consists of three steps. We first manually, haar like feature is applied for Thai face cartoon detection. Second, those faces are extracted feature using eigenface. Final, those features are recognized using Euclidean distance. For experimental result, detection rate of 95% and recognition rate of 97%.
Ensemble Learning Model for Diabetes Classification
Authors: Nai-Arun Nongyao , Sittidech Punnee
Published: May 2014

This paper proposed data mining techniques to improve efficiency and reliability in diabetes classification. The real data set collected from Sawanpracharak Regional Hospital, Thailand, was fist analyzed by using gain-ratio feature selection techniques. Three well known algorithms; naïve bayes, k-nearest neighbors and decision tree, were used to construct classification models on the selected features. Then, the popular ensemble learning; bagging and boosting were applied using the three base classifiers. The results revealed that the best model with the highest accuracy was bagging with base classifier decision tree algorithm (95.312%). The experiments also showed that ensemble classifier models performed better than the base classifiers alone.
Enhancing Decision Tree with AdaBoost for Predicting Schizophrenia Readmission
Authors: Thongkam Jaree , Sukmak Vatinee
Published: May 2014

A psychiatric readmission is argued to be an adverse outcome because it is costly and occurs when relapse to the illness is so severe. An analysis of systematic models in readmission data can provide useful insight into the quicker and sicker patients with schizophrenia. This research aims to develop and investigate schizophrenia readmission prediction models using data mining techniques including decision tree, Random Tree, Random Forests, AdaBoost, Bagging and a combination of AdaBoost with decision tree, AdaBoost with Random Tree, AdaBoost with Random Forests, Bagging with decision tree, Bagging with Random Tree and Bagging with Random Forests. The experimental results successfully showed that AdaBoost with decision tree has the highest precision, recall and F-measure up to 98.11%, 98.79% and 98.41%, respectively.
Development of Instruction Model by FATAC Model on Electromagnetic Field and Wave for Electrical Engineering Program
Authors: Promtee Alongorn , Akkanit Churairatchinda
Published: May 2014

This research aims to develop instruction model using cognitive learning theories on electromagnetic field and wave for undergraduate of electrical engineering program. The new instruction model called FATAC model was developed. It consists of 5 steps as; 1) Find 2) Adjust 3) Teach 4) Actions and 5) Conclusion. The content of dissertation has 3 Units; 1) Maxwell equations and electromagnetic wave are direct variation with time 2) Microwave planar and 3) Poynting vector and wave propagation. Thirty students of level 3 in technical education, rajamangala university of technology isan, khonkaen campus were a sampling group. Tools of dissertation included lesson plans, learning media as powerpoint presentation, electromagnetic wave propagation simulation program, wave propagation demonstration set, and filed strength meter.
The research results consisted of; 1) The opinion on the FATAC model was high level (=4.21,S.D.=0.48). 2) The learning effectiveness of the instructional model was 76.15/76.73 (higher than 75/75 of the hypothesis). 3) The quality of instruction package by experts was high level (=4.27 ,S.D=0.62) and 4) The mean of satisfaction of the sampling group was high level (=4.23 ,S.D=0.57).
Therefore, in conclusion, instruction model using cognitive learning theories on electromagnetic wave and propagation for undergraduate of electrical engineering program can be applied for electromagnetic theory subject and high efficiency.