bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Cost Optimization in High Speed Hard Turning Using Simulated Annealing Algorithm
Authors: Al Hazza Muataz Hazza F. , Adesta Erry Y.T. , Hasan Muhammad Hasibul , Shaffiar Norhashimah
Published: July 2015

Selecting the cutting conditions to optimize the economics of machining process as assessed by energy machining cost is essential. The aim of this research is to determine the optimum cutting parameters that minimize the energy cost needed for removing one cubic centimetre of material in High Speed Hard Turning (HSHT) process. To achieve that, a set of experimental machining data to cut hardened steel AISI 4340 was obtained with different ranges of cutting speed, feed rate, depth of cut and negative rake angle using mixed ceramic as a cutting tool. Regression models have been developed by using Box-Behnken design as a design of experiment. Then, the Simulated Annealing Algorithm (SAA) has been used to optimize the cutting parameters. The data collected was statistically modelled. The results show that the range of minimum energy cost to remove one cubic centimetre of material for the three techniques can be achieved in the range of 300 to 308 as a cutting speed, -12 for cutting rake angle, 0.125 as a feed rate and 0.15 as a depth of cut.
Multi Objective Optimisation for High Speed End Milling Using Simulated Annealing Algorithm
Authors: Al Hazza Muataz Hazza Faizi , Seder Amin M.F. , Adesta Erry Y.T. , Riza Mohammad , Shaffiar N.M.
Published: July 2015

Machining at high cutting speeds produces higher temperatures in the cutting zone. These temperatures affect the surface quality and flank wear progress. Therefore, determining the optimum cutting levels to achieve the minimum surface roughness and flank wear is an important for it is economical and mechanical issues. This paper presents the optimization of machining parameters in end milling processes by using the simulated annealing algorithm (SAA) as one of the unconventional methods in optimization. The minimum arithmetic mean roughness (Ra) and minimum flank wear length were the objectives. The mathematical models have been developed, in terms of cutting speed, feed rate, and axial depth of cut by using Response surface Methodology (RSM). This paper presents the optimum cutting parameters: cutting speed, feed rate and depth of cut to achieve the minimum values of surface roughness and minimum flank wear length. The results show that the cutting speed in the range of 200 m/min, feed rate of 0.05 mm/tooth and depth of cut of 0.1mm gave the minimum arithmetic mean roughness (Ra) for 164 and minimum flank wear for 0.0379 in the boundary design of the experiment after 8000 iteration.
Effect of Polycarboxylate Ether (PCE) Addition to Physical and Mechanical Characteristics of High Performance Concrete
Authors: Ali Maisarah , Ahmad Muhamad Zharif , Saad Siti Asmahani
Published: July 2015

Conventional concrete does not have durability and higher strength as produced by high performance concrete (HPC). It is known that the HPC possess the following three properties which are high workability, high strength, and durability. The introduction of polycarboxylate ether (PCE) superplasticizer was proved to enhance the workability of concrete even though at a lower water to cement ratio. The study was conducted to find the optimum dosage of PCE and to compare its compressive strength, physical characteristics and morphology of the HPC. The result of the test shows that the high performance concrete (HPC) with addition of 0.5% polycarboxylate ether (PCE) superplasticizer of the cement mass have the highest compressive strength and excellent physical properties.
Effect of Rice Husk Ash (RHA) on Physical Property and Mechanical Strength of Concrete
Authors: Ali Maisarah , Fadzil Mohd Syafiq , Saad Siti Asmahani
Published: July 2015

Fast depleting natural resources, huge consumption of energy, and environmental hazards involved in the production of cement has inspired researchers to find partial replacement of cement using other or similar materials. Rice husk ash (RHA), an agricultural waste, is classified as “a highly active pozzolan” because it contains a very high amount of amorphous silica and a large surface area. Rice husk is natural fiber that has the advantages of low density, low cost and biodegradable. In Malaysia paddy is grown locally especially in northern states of Peninsular Malaysia. Rice husk is a by-product of paddy being process into rice. These make it a natural candidate for cement replacement agent especially in Paddy producing countries. In this paper, RHA was introduced as the micro filler in concrete mixtures. The replacement of RHA which is lighter as compared to the Ordinary Portland Cement results in decreasing density of cement fiber composite and less permeable concrete.
Investigation of Low Voltage Varistor Using TiO2 as Base Material and SiO2, Bi2O3 and WO3 as Dopants
Authors: Begum Shahida , Kothadapani Zarrin , Selvaraj Mokanaraju K. , Muntasir Mohamed
Published: July 2015

Varistor with TiO2 as the base and SiO2, WO3 and Bi2O3 as dopants were investigated to create a low voltage varistor. The physical, mechanical, microstructural and electrical properties were studied where the concentration of SiO2 was varied but the concentration of WO3 and Bi2O3 was fixed. Physical and mechanical characterization consisted of green and fired density, axial and radial shrinkage and Vickers Hardness. Electrical evaluation on the other hand consisted of non-linear coefficient, breakdown voltage, power loss and clamping ratio. Non-linear coefficient of 2.16, very low breakdown voltage of 5.538V/cm and minimal power loss of 0.0124mW was achieved. It was found that optimum results were achieved with 98.3% TiO2, 0.7% SiO2, 0.5%Bi2O3 and 0.5%WO3.
The Glass Transition Temperature of Iron and Titanium Containing Phosphate Based Glasses
Authors: Shaharuddin S.I.S. , Ahmed I. , Furniss D. , Parsons A.J. , Rudd Chris D.
Published: July 2015

In this study various compositions in the phosphate based glass (PBG) system of (50-x)P2O5-40Ca-(5+x)Na-5TiO2 and (50-x)P2O5-40Ca-(5+x)Na-5Fe2O3, where x= 5 and 10 were investigated for glass transition temperature (Tg) via thermo mechanical analyser (TMA) and differential scanning calorimetry (DSC). The amorphous nature of the glasses was confirmed via XRD. The Tg measured via DSC was consistently higher by 19°C-29°C compared to TMA and was due to the thermal history and the heating rate of the samples. The Tg increased with increasing phosphate content in both glass systems. The Tg for Ti containing PBG was found to be in the range of 453°C-500°C whilst Tg for Fe containing PBG was in the range of 449°C-494°C. Consistently higher Tg for the Ti containing glass series compared to the Fe containing glasses may be attributed to the smaller ionic radius and therefore higher field strength of Ti4+.
Formation of Hydrophobic Surface Using Two Stages Electrodeposition Method
Authors: Ani Mohd Hanafi , Ramli Nor Shahirah , Wan Yusoff Wan Ahmad Yusmawiza , Mustafah Yasir Mohd , Othman Raihan
Published: July 2015

A simple and economical route based on a ZnCl2mediated process was developed to synthesize hierarchical flower-like ZnO micro/nanoflakes on the surface of copper foil by 2 stages electrodeposition method (2M ZnCl2– 0.5M ZnCl2). The prepared flakes were characterized by XRD and SEM. The morphology of ZnO can be tuned from simple isolated nanoflakes to ordered flower-like shape using this method. The surfaces retain good hydrophobic stability in long period time.
Physical Properties of Electroless Nickel-Tungsten Coating on Mild Steels Obtained from Acetic Bath
Authors: Mahmood Hameed , Harun Nurliyana , Suryanto  , Hilmy Irfan
Published: July 2015

Electroless deposition of nickel tungsten on mild steel was conducted using acetic bath, containing nickel sulphate and sodium tungstate in the alkaline medium. The influence of sodium acetate and sodium tungstate on deposits was investigated and characterized using scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX) and x-ray diffraction (XRD) to assess the phase, content and microstructure features. The surface roughness of coating was measured using atomic force microscope (AFM) while the hardness was investigated using Vickers microhardness. The results show that deposits have smooth surfaces, Ra = 0.53 μm, with a nanocrystalline structure, crystallite size hardness of deposits decreases as the concentration of sodium tungstate increases.
Surface Features of TIG Melting Coated CP-Titanium
Authors: Adeleke S.A. , Maleque M.A.
Published: July 2015

Tungsten inert gas (TIG) melting process is increasingly find successful application in many aspects of engineering part components. In this study, TIG melting of Fe-based coating has been successfully developed by precoated iron, carbon and silicon (Fe-C-Si) powders on commercial purity titanium (CP-titanium) surface under three different glazing speeds such as 1.0 mm/s, 1.5 mm/s and 2.0 mm/s and constant energy input of 1350 J/mm in an argon gas environment. The effects of glazing speeds on the surface topography, melt geometry, microstructure and hardness were investigated. Rippling marks were found on all the track surfaces which portends that good solidification of the molten melt pool had taken place near the base metal. The melt pool layers consisted of higher population of dendrites and the population were found to decrease with increasing glazing speeds. The resolidified surface layer of the dendrites developed hardness 3 to 4 times higher than that of the base material. According to the enthalpy reactions due to formation of titanium carbide, silicon carbide and iron carbide during TIG melting of Fe-C-Si coated titanium surface are considered to be responsible for larger melt depth. These results showed that surface properties of CP-titanium can be enhanced with Fe-C-Si using TIG melting process.
Optimization of Hardness Behaviour of TIG Modified Ceramic Coating Using the Taguchi Approach
Authors: Bello Kamilu Adeyemi , Maleque Md Abdul , Ahmad Zuraida , Mridha Shahjahan
Published: July 2015

The increasing need for energy efficient tribo-composite surfaces has led to the enhancement of surface properties of engineering components through parameter processing control. This study was carried out to investigate the hardness behaviour of low alloy steel (LAS) surface modified with TiC under a tungsten inert gas (TIG) arc torch. The effects of welding current, traversing speed, arc voltage and argon flow rate on surface hardness during the surface alloying treatment were analyzed using Taguchi’s experimental design. The hardness behaviour of the TIG-processed composite coating was assessed with a Wilson Wolpert microhardness machine. The analysis of the experimental results based on the Taguchi’s design revealed that the welding speed and welding voltage are the most significant process parameters influencing the surface hardness performance of the composite coated layer. The signal-to-noise response was used to identify the optimum parameter combination for maximizing the surface quality characteristics. The validity of this approach was confirmed based on the good agreement between the predicted value and experimental result obtained at the tested optimal conditions.
A Study on the Mechanical and Thermal Properties of ENR Filled with Dual Fillers
Authors: Mansor Mohd Khairulniza , Ismawi Hassim Dayang Habibah Abang
Published: July 2015

The effects of dual fillers, carbon black (CB) and mineral filler mixture (MFM) in epoxidized natural rubber (ENR) compound using BR1600 internal mixer were investigated. In this study, the processability of the compound improved and the cure time decreased with partial replacement of CB with MFM. Results also showed that compound filled with partial replacement of 20 phr of CB with MFM exhibited comparable tensile strength value with compound filled with 50 phr CB as single filler. Nevertheless, based on Thermogravimetri analysis (TGA), ENR filled with 50 phr CB gave higher char yield which can ascribe to the better stability of the char layer formed.
Mechanical Properties of Bamboo Fibre Composite Incorporating Pulverized Fuel Ash
Authors: Ali Maisarah , Saad Siti Asmahani , Farah Elyani Khairuddin Noor , Sidek Ammar Hamzi , Salim Muhammad Faiz Md.
Published: July 2015

This study reports the findings of an experimental investigation for bamboo fibre (BF) reinforced concrete board. In this research, all specimens were prepared at 0.4 water/binder ratio. There were two series of specimens namely A series and B series. The A group utilizes only ordinary portland cement (OPC) as binder. Meanwhile, series B specimens uses binary binders, which were combination of OPC and pulverized fuel ash (PFA) with PFA to OPC ratio of 0.2. The performance of flat board plates with different percentage of bamboo fiber ranging from 0% to 5% and 20% PFA incorporation of cement weight were tested for bending strength (flexural) and compressive strength in accordance to BS 5669: Part 1 for particleboards. Specimens are cured in water curing tank and tested at 3, 7 and 28 days for compression test. Meanwhile for flexural strength test, the specimens are tested at 28 days. It is found that flexural and compressive strength increases with addition of BF. The optimum compressive and flexural strength at 28 days are recorded with 3% incorporation of BF for both PFA and control samples. Therefore, utilizing natural fibre and waste material for partial substitution of cement content in producing internal wall paneling system could contributes to the economic appeal and promoting sustainable construction approach.
Physical and Mechanical Properties of Waste Sawdust Polymer Composite for Marine Application
Authors: Mohd Idrus Muhammad Abdul Mun'aim , Othman Mohd Fadhil Safy
Published: July 2015

In this research, wood polymer composite (WPC) were produced by using the combination of waste sawdust (Cengal and mixed sawdust), unsaturated polyester resin and a catalyst as the curing agent. The WPCs were produced at four levels of sawdust loading (5 wt% - 20 wt %) with resin and 3% of catalyst added to study the mechanical and physical proeprties. Micro structural analyses were done by scanning electron microscopy and the result showed that the sawdust filler were evenly dispersed in the resin matrix. The mechanical and physical properties of the composites are higher than unfilled resin. The optimum ratios were obtained for sawdust composite at 10 wt% where it showed the best performance than others.
SEM Analysis of Kenaf Sandwich Panel
Authors: Halim Zahurin , Othman Maizatulnisa , Abdul Rahman Siti Khadijah
Published: July 2015

This study focus on the cross-sectional image of sandwich panel; the kenaf dispersion in core and the skin core interaction. Fracture image is the image outcome of flexural test. The main element of the core structure is kenaf and the skin used in this study is galvanised steel sheet. Skin thickness being used in this research is 1.0 mm and 1.2 mm.
The Effects of Various TPNR Binder Compositions on Feedstock Preparation for MIM Process
Authors: Norita Hassan , Ahmad Sahrim , Muhamad Norhamidi , Omar Mohd Afian , Hassan Noor Azlina
Published: July 2015

Metal injection moulding (MIM) feedstock is a mixture of metal powder and binder. The function of the binder system is to provide flow ability of the metal particles and shape retention of the moulded parts. The behaviour of the feedstock depends greatly on the binder formulations and its composition. In these studies, the possibility of using thermoplastic natural rubber (TPNR) as a binder system has been preliminarily investigated. The TPNR binder containing of natural rubber (NR) and polyethylene (PE) were studied at variable compositions. The characterization includes of mixing parameter, mixing torque and SEM micrograph of TPNR. Results show that the optimum composition of NR is about 40% in volume fraction of TPNR binder. The rheological results of the feedstock are considered to be used in MIM process as bio-composite binder.
Production and Chemical Compounds of Gaharu Extract by Using Supercritical Fluid Extraction (SFE) of Unsoaked Gaharu at Different Pressure
Authors: Haji Che Daud Mohd Radzi , Hamdan Huzaifah
Published: July 2015

Aquilaria species from the family of Thymelaeceae are the main source of gaharu, which has been classified as one of the most highly valuable, non-timber products in the world market. Currently, the method used for extracting gaharu essential oil is by using hydrodistillation. However, this method is inefficient where it produced low yield of oil with long time of extraction and thus increasing the production cost. To overcome this problem, the extraction of gaharu essential oil using Supercritical Fluid Extraction (SFE) with pressure 20MPa, 30MPa and 40MPa at 65 °C for 2 hours was studied. Result obtained after 2 hours of experiment was 0.6% of yield, which was higher compared to 0.2% yield of gaharu essential oil obtained via 3 days of hydrodistillation. After an extraction process, the product will be analyzed by using Gas Chromatography-Mass Spectrometry (GC-MS) to determine the chemical compounds and composition in the Gaharu SFE’s extract. Over eighteen to thirty-one compounds were identified in SFE extract compared with fifty-five identified in the hydrodistillated oil. The mutual occurrence of chemical compounds in all three samples in SFE was dimethyl phthalate, 8-epi-.gama.-eudesmol, diethyl Phthalate and 2-3-Butanediol. In comparison, the major compounds identified in hydrodistillated oil were 4-phenyl-2-butanone, jinkoh-eremol and α-guaiene (Saiful Nizam & Mashitah, 2010). There were certain aromatic sesquiterpenes compounds that were identified in this study, such as Globulol, Alloaromadendrene Naphthalene, 10s, 11s-Himachala-3(12), 4-diene, .delta.-Selinene and (-) - Aristolene.
Sol-Gel Derived Zinc Doped Calcium Phosphate Bioceramics Prepared via Different Sintering Strategies
Authors: Sopyan I. , Gunawan  , Suryanto
Published: July 2015

Sinterability of zinc doped calcium phosphate (CaP) sintered via conventional pressureless and two step sintering methods was investigated. The starting powders have been synthesized through sol-gel method with zinc concentration varied in the range of 0, 1, 4, and 10mol%. After uniaxial pressing, the compacts were sintered via conventional pressureless sintering. The dense samples were studied in terms of the phase stability, relative density, Vickers hardness, and fracture toughness. The phase of samples was hydroxyapatite and β-tricalcium phosphate. The presence of Zn caused a change in the sintering behaviour of dense calcium phosphate. Zn doping has improved relative density of 4mol% Zn-doped by 8.1% compared to undoped fired at 1300°C. The maximum fracture toughness of 1.43 MPa.m1/2 and Vickers hardness of 3.44 GPa were achieved at 1200°C by 4 mol% Zn-doped. The low Vickers hardness and fracture toughness obtained for dense samples sintered of two step sintering compared to conventional pressureless sintering is due to the low measured bulk density. This study showed that conventional pressureless sintering was beneficial in producing high toughness of Zn doped CaP.
Thermal Analysis on Dehydroxylation of Sol-Gel Derived Zinc Doped Calcium Phosphate Powders
Authors: Gunawan  , Sopyan I.
Published: July 2015

The dehydroxylation of Zn free and 4 mol% Zn CaP powder was investigated using thermogravimetric analysis over the range of room temperature to 1200 °C. The kinetic result of dehydroxylation of Zn free and 4 mol% Zn CaP was calculated by means of the Ozawa–Flynn–Wall method. The XRD result indicated that the amount of Zn incorporated in HA lattice influences the phase stability of HA as it decreases with an increase in Zn concentration. According to calculated activation energy and conversion degree, the kinetics of HA dehydroxylation was identified, which included four successive conversion stages kinetically controlled by different rate-controlling processes. The dehydroxylation analysis of TG/DTG data show that Zn incorporation in HA lattice influences the phase stability of HA.
Trans-Esterification of Crude Palm Oil Liquid Waste to Biodiesel
Authors: Harmiwati  , Rahmad Dedy
Published: July 2015

Esterification and trans-esterification reactions are an alternative solution for the production of biodiesel from Crude Palm Oil waste. The two previous studies show that the yield obtained was less than 80%. It is necessary to investigate the optimum condition of trans-esterification operation in biodiesel production from CPO waste. Variables used are temperature, time, ratio of molar triglyceride with methanol, and catalyst concentration. According to preliminary temperature treatment variations, it is determined that optimum temperature is 55°C. Meanwhile, the time treatment variations showed that optimum time is 60 minutes. For the ratio of molar triglyceride with methanol, it is determined that 1:10 is the optimum ratio. And last, for the experiment variations of NaOH concentrations it is discovered that the optimum concentration is 1.25%-b. And to conclude the research, the optimum condition for each variable was used where biodiesel’s yield can reach up to 96.67%.
Effect of Dispersants on Microstructures of Nano Alpha Alumina Developed from Aluminium Dross Waste
Authors: Anis Sofia S. , Samat Noorasikin , Meor Sulaiman Meor Yusoff
Published: July 2015

This paper compares the effect of dispersants which are Sodium Laureth Sulfate (SLS) and distilled water (DW) on the crystallization, particle size distribution and morphological behavior of nanoalpha Alumina (α-Al2O3) synthesized from Aluminium (Al) dross waste. The synthesizing of nanoα-Al2O3 via wet milling method was performed using a planetary mill for 4 hours at a speed of 550 rpm. The nanoα-Al2O3 powders with dispersants were characterized with x-ray diffraction (XRD), particle size analyzer (PSA) and transmission electron microscopy (TEM). XRD analysis shows the broadening and shifting of peaks after the sample was calcined at 1300 °C, indicating high crystallinity. The crystallite size of α-Al2O3 milled with SLS is also smaller than the α-Al2O3 milled with DW. These results are consistent with the PSA analysis in which the graphs displayed a symmetrical trend. Then, the PSA analysis is validated with TEM observation up to 100000x magnification, particularly for α-Al2O3 milled with SLS.
Effect of Voltage on Colloidal Gold (Au) Nanoparticles Produced Using Electro-Dissolution-Reduction Method
Authors: Haiza Haroon , Yaacob I.I. , Ahmad Azhar Ahmad Zahirani
Published: July 2015

Colloidal gold nanoparticles have been successfully prepared using a simple two-electrode cells connected to a DC power supply. During the electro-dissolution-reduction process, the bulk gold at the anode oxidized into gold cations which then reacted with the chloride ions to form aurochloride complex. The complex ions were then reduced by the citrate ion to form colloidal gold nanoparticles. The size and shape of the nanoparticles were modulated by varying the terminal voltages. The colloidal gold nanoparticles obtained were characterized by field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and ultraviolet-visible spectrophotometer (UV-Vis). From FESEM analysis, it was found that by increasing the voltage, the size of colloidal gold nanoparticles produced marginally decreased. The mean sizes of gold nanoparticles were roughly about 23.5 nm, 23.2 nm and 19.3 nm for 32 V, 36 V and 40 V, respectively. TEM micrograph showed that the shape of gold nanoparticles obtained is almost spherical. The characteristic peaks of UV-Vis spectra revealed that the suspension was indeed colloidal gold nanoparticles.
Keywords: Gold, Nanoparticles, Electro-dissolution-reduction
Study of Mechanical and Flammability Properties of Polypropylene/Microcrystalline Cellulose Composites Filled with Nano-sized Aluminium Hydroxide (ATH) Particles
Authors: Samat Noorasikin , Zulkapli N. , Halim Zahurin , Ahmad Zuraida , Habibah A.I.H.Dayang
Published: July 2015

The mechanical and flame properties of polypropylene/ microcrystalline cellulose (MCC) composites containing different loading of aluminium hydroxide (ATH) nanoparticles from 3 to 20wt% was studied. Maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the composites. The mechanical properties of PP/MCC composites were characterized by tensile and impact tests while the flame properties were evaluated by UL-94 and oxygen index tests. It was shown that the addition of ATH improved the mechanical and flame resistance properties PP/MCC composites, mainly in the composites with MAPP. Fracture surface observations in samples with MAPP show better dispersion and adhesion of fillers (MCC and ATH). Flame retardancy also enhanced along with the ATH loading.
Development of an Automatic Plant Monitoring System
Authors: Bhuiyan Moinul , bin Tengku Azmi Tengku Muhammad Afif
Published: July 2015

Automated system operates with less human interaction which reduces job overheads. This paper represents an automated plant monitoring system which could be applicable for practical plantation field in Malaysia to boost up the agricultural productions. The monitoring system, which is presented in this paper, uses three sensors to measure humidity, temperature, and moisture of the surroundings of the test plant and provides the most suitable amount of water to plant depending on the coefficient generated from the sensors’ data. Arduino Global System for Mobile Communication (GSM) Shield is also integrated with the system to monitor the process using mobile phone. Considering the reduction of environmental pollution, solar power system is used to power-up the designed monitoring system. Low cost and good results of practical experimentations present that the system is viable to implement in large scale plant monitoring and irrigation.
Development of Catalytic Converter Using Non-Precious Metals
Authors: Mohiuddin A.K.M.
Published: July 2015

This paper shows the uses of low cost metal for the development of catalytic converters. While bringing down the cost, attention must be paid on the performance capability of the catalytic converter. The objective of this work is to develop and design a low cost catalytic converter using copper as the main catalyst in the catalyst system. Copper powder was chosen as the alternative catalyst to reduce the use of precious group metals (PGMs) platinum, palladium, and rhodium. A spark ignition engine’s catalytic converter has to perform the oxidation of CO, oxidation of HC and reduction of NOxsimultaneously in order to satisfy its performance requirement. These three chemical reactions are taking place simultaneously in a three way catalytic converter. To investigate the chemical kinetics and fluid flow characteristics of a catalytic converter, simulations have been carried out using COMSOL. From COMSOL MULTIPHYSICS, catalytic converter’s velocity field and pressure distribution have been simulated. From COMSOL REACTION ENGINEERING LAB, NO and CO concentration from a catalytic converter kinetics model have been plotted. NO and CO conversion for different air to fuel ratio had shown that for rich mixture, NO reduction reaches its maximum but CO oxidation is at its minimum. In lean mixture, CO oxidation is at its maximum but NO reduction is at its minimum. Simulations have shown the actual characteristics of the catalytic converter performance. The flow throughout catalytic converter and the backpressure have successfully determined and the catalyst conversion efficiency also shown clearly.
Cutting Temperature Behaviours in End Milling of Pocket by Applying Contour-In Tool Path Strategy
Authors: Riza Muhammad , Adesta Erry Yulian Triblas , Suprianto M. Yuhan
Published: July 2015

Cutting temperature generated during high speed machining operations has been recognized as major factors influence tool performance and workpiece geometry. This paper aims to model the cutting temperature and to investigate cutting temperature behaviours when contour-in tool path strategy applied in high speed end milling process. The experiments were carried out on CNC vertical machining center by involving PVD coated carbide inserts. Cutting speed, feed rate and depth of cut were set to vary. Results obtained indicate that cutting temperature is high in the initial stage of milling and at the corners region or turning points region. Portion of radial width of cut with workpiece in combination with the abrupt change of the milling path direction occur particularly in acute internal corners of a pocket leads to rise of cutting temperature.
Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants
Authors: Sarwar Muhammad , bin Abd Majid Mohd Amin
Published: July 2015

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.
Mode I Stress Intensity Factor for a Cracked Plate with an Integrated Piezoelectric Actuator
Authors: Abuzaid Ahmed , Hrairi Meftah , Dawood Mohd Sultan
Published: July 2015

The fracture performance of cracked structures is dominated by singular stress in the crack tip vicinity. In fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of structures when a critical stress intensity factor is reached. In the present work linear fracture mechanics is applied in order to obtain the fracture toughness parameters of a cracked plate integrated with piezoelectric actuator under mode I loading. Analytical model was derived to represent the relation between piezoelectric parameters and stress intensity factor and energy release rate. The results indicate that the stress intensity factor decreases linearly with the application of the different piezoelectric actuator voltages.
Comparative Study of SPWM and HEPWM Techniques for Photovoltaic Inverter
Authors: Bendib Douadi , Akel F. , Chikh M. , Larbes C. , Laour M. , Mahrane A.
Published: July 2015

This paper presents an evaluation study of two pwm techniques applied to a three-phase voltage source inverter supplied by photovoltaic (PV) energy sources. A Pspice-based model of the pv array is developed and tested. The power and currant of the pv array versus the voltage is plotted. Then the pv array is connected to a basic three phase voltage source inverter VSI. Two control techniques are used. The first one is the classic sinusoidal pulse width modulation spwm, which is based on the comparison of two signals, the sinusoidal reference and a triangular carrier. The second one is based on the principle of harmonic elimination. The system is simulated using orcad-pspice, the results are given, discussed and compared based on different performance indices (output quality, thd, frequency).
IIUM CubeSat Structural Subsystem Design
Authors: Isharuddin Siti Sarah , Okasha Mohamed , Ibrahim Sultan
Published: July 2015

This paper investigates the development process of a CubeSat model structure subsystem for the International Islamic University Malaysia (IIUM). Many universities around the world have participated in similar CubeSat satellite projects. CubeSat satellite enables to design and produce a fully functional satellite at low cost compared to other types of satellites. It gives the engineering students especially the aerospace one, a hands-on education, and learning about how to design their own satellite. This paper will discuss the procedures that can be used to design and test the CubeSat structure subsystem considering design goals and constraints. The analyses will consider the structure static and vibration tests utilizing ANSYS Workbench platform and SolidWorks software and the simulation results will be compared with the experimental test results on the physical model.
Effect of Microwave Sintering Treatment to the Flank Wear of Titanium Carbide Tools in Milling Operations
Authors: Iqbal Mohammad , Ariff Tasnim Firdaus , bin Mat Roseh Mohd Shahrul Fahmi , Al-Hazza Muataz Hazza Faizi , Hilmy Irfan , Suryanto
Published: July 2015

The paper reports the research on the improvement of tool wear resistant of Titanium Carbide (TiC) cutting tool after microwave post sintering treatment. Titanium Carbide square milling insert was microwave sintered at 600°C with 15 minutes of holding time. The face milling operations were conducted to Carbon Steel S45C block (130 mm x 95 mm x 40 mm) by using both of original and microwave sintered insert at 5 different cutting speed (60, 90 , 120 , 150 and 180 m/min), constant feed rate (0.2 mm/tooth) and constant depth of cut (0.2 mm/tooth). The flank wear of the insert was measured every nearest 10thminute of complete cutting passes. The results of the experiment show that microwave post sintering treatment improves the tool resistant of the TiC insert. The flank wear of the sintered insert is lower at any machining time and all cutting speed. The research also found that the percentage of the improvement is lower at higher cutting speed compare to lower cutting speed.
Painting Process Improvement through Six Sigma Approach in a Malaysian Vehicle Assembly Company
Authors: Abdul Rahman Mohamed , Mohiuddin A.K.M. , Abdullah Hanani
Published: July 2015

Painting is an important process in the automotive assembly to give more attractive appearance to the vehicles and to provide the layer of protection against corrosion and weathering. The objective of this paper is to identify and analyze the factors affecting the quality of painting process at Company RST’s Paint Shop. The paint shop was unable to perform the painting process satisfactorily and deliver the painted vehicle bodies as per customer specifications. The study concentrated on the fiber defect detected at Top Coat Area as the major problem of paint deficiency. Using activities like Genba investigation, data collection, trials and data analysis, the root causes of the problem were identified. Six Sigma DMAIC approach was utilized in conducting the improvement activities. Through designed experiments conducted to determine the best parameter setting of the spray gun used in the painting process, it was found that 3.5 bars for air pressure and 450 ml/minutes for fluid delivery resulted in the lowest paint defect. The use of Six Sigma DMAIC approach had succeeded in helping the company to minimize paint fiber defect per unit (DPU) from 10 to less than 3 DPU. The results from the study have provided an insight on successful deployment of DMAIC through application of its various statistical tools and techniques, and as the systematic problem-solving framework on solving actual industrial issues such as automotive painting problem.
Design of a Heuristic for Balancing a Multi-Stage Production Flow Line
Authors: Kays H.M.E. , Karim A.N. Mustafizul , Tajudin M.N.B. , Abdesselam M.
Published: July 2015

A production flow line balancing problem for automotive industry has been studied. A batch of an end item is produced by transforming sheet metals into parts at different manufacturing stages followed by assembly operations. The forming operations of the sheet metals into various parts and their assembly works are illustrated through 22 different tasks. Some of the tasks have the processing times greater than the takt time and are categorized as extra-long tasks. Attempts were made to solve this intricate line balancing problem by adopting the Ranked Positional Weight (RPW) method. But the solution given by the RPW model loses its exactitude due to the presence of the extra-long tasks. In this research a heuristic approach based on RPW is developed through which the problem has been resolved in an efficient and effective manner and hence the proposed heuristic is deemed to be capable of balancing production lines having such extra-long tasks.
Evaluating Delamination at Entry of Drilled Carbon Fiber Reinforced Polymer (CFRP) Composite with Diamond Coated Ball Nose Drills
Authors: Konneh Mohamed , Al Hazza Muataz Hazza Faizi , Sidek Atiah Abdullah , Samsul Bahri Ruhaki Huda
Published: July 2015

This paper presents the investigation of the influence of machining parameters on delamination at entry of drilled holes after drilling into CFRP composite using 4 mm-diameter 2-fluted carbide drills coated diamond. The delamination at tool entry was analyzed in terms of delamination factor on the basis of analysis of variance (ANOVA) of Central Composite Design (CCD) of experiments. It is found that spindle speed is the most influential factor for the drilling of CFRP within the range of cutting parameters examined. The lowest delamination factor (1.006) was generated at rotational speed, 4400 rpm and feed rate, 270 mm/min; and the highest delamination factor (1.123) generated at rotational speed, 537 rpm and feed rate, 180 mm/min. A mathematical model has been predicted for the delamination at tool entry. The relationship between the machining variables and output variables is also established.
Effect of Powder Concentration on EDM Performance during Machining Mild Steel
Authors: Khan Ahsan Ali , Azmi Nurfarah Wahid , Odenan Mohd Azim , Zain Zakatia Mohd
Published: July 2015

This research work describes the effect of powder concentration in dielectric fluid during electrical discharge machining (EDM) of mild steel on material removal rate (MRR), electrode wear rate (EWR) and work surface roughness (Ra). The machining parameters studied in this research are current (4.5A, 5.5A, and 6.5A) and concentration of the powder (30g/l, 60g/l, and 90g/l). It was decided to use copper (Cu) as the electrode, mild steel as the work material and tantalum carbide (TaC) as the powder to be mixed with the dielectric. Design-Expert software was used to design and analyze the experiments. The performance of machining was analyzed and it was found that powder concentration does not have much effect on MRR or work surface roughness (Ra). At low current powder concentration reduces electrode wear rate (EWR), but at higher current the situation is opposite. It was also found that in all conditions, MRR and EWR increases with increase in current. A higher current produces stronger spark with higher energy that melts more materials from the workpiece and the electrode. As a result both MRR and EWR increases and job surface becomes poor.
Effect of Carbon Black Content and Molding Pressure on the Thermal Conductivity of SiC/Si Ceramic Composites
Authors: Li Qi Song , Zhang Yu Jun , Sun Hai Bin , Zhai Yan Xia , He Chao
Published: July 2015

SiC/Si ceramic composites have been considered as promising candidate materials for heat exchanger due to their good thermal conductivity and corrosion resistance. In this work, the SiC/Si ceramic composites were fabricated by liquid silicon infiltration technique, and the effect of carbon black content and molding pressure on thermal conductivity of the composites was studied. With carbon black content increasing from 5 wt. % to 25 wt. %, the thermal conductivity increased from 42.36 W/(m·K) to 65.60 W/(m·K) when molding pressure was fixed as 50 MPa. With molding pressure increasing from 30 MPa to 110 MPa, the thermal conductivity of SiC/Si ceramic composites with 20 wt. % carbon black content increased firstly, and then decreased, obtaining a maximum thermal conductivity of 71.62 W/(m·K) under 90 MPa. The SiC/Si ceramic composites with an optimal thermal conductivity of 76.55 W/(m·K) at room temperature were obtained when carbon black content and molding pressure were 25 wt. %, 90 MPa, respectively.
Effects of Pore Former on Properties of Alumina Porous Ceramic for Application in Micro-Filtration Membrane Supports
Authors: Bao Qi Fu , Dong Wei Xia , Zhou Jian Er , Wang Yong Qing , Liu Yang
Published: July 2015

Due to its excellent chemical stability, high temperature resistance and mechanical properties, alumina porous ceramic was the first choice of the production of microfiltration membrane support body material. In this paper, alumina porous ceramic was prepared by alumina as main materials and adding proper amount of adhesives and sintering additives. Effects of the kinds and addition of pore formers, such as starch, graphite and carbon-black, on properties of alumina porous ceramic was studied. The porosity of the fired samples was evaluated by Archimedes law. The fired samples were characterized by scanning electron microscopy (SEM), compressive strength and mercury porosimeter measurements. Alumina porous ceramic composition was prepared by mixing 100% alumina with different particle size and 8 % graphite pore former. The sample was pressured at 10 MPa and fired at 1650 °C for 2 h, and endowed with 6-8 μm of the average pore diameter, 37.65 % of the porosity and 40.33 MPa of the compressive strength, respectively. The influence law of the kinds and addition of graphite pore former on the performance of alumina porous ceramic was studied for application in micro-filtration mmembrane supports.
A survey of car guards in Tshwane: Implications for private security policy and practice
Authors: Steyn Francois , Coetzee Annika , Klopper Harriet
Published: July 2015

Car guards form an integral part of South Africa’s urban landscape. This article reports on a survey of 144 car guards in Tshwane to identify the implications of their work for private security policy and practice. The profile of respondents reflects their low socio-economic status and marginalisation from the formal economy. The study found that some car guards struggle to survive financially because of the daily levies payable to car guard agencies and the managers of shopping centres. The results of the study suggest that, despite positive sentiments and advancements in policy and legislation, regulation of the formal car guarding industry remains constrained due to inadequate implementation and monitoring. The article offers insights into the factors affecting car guarding as a form of private security in South Africa.
Characterization of ambient volatile organic compounds and their sources in Beijing, before, during, and after Asia-Pacific Economic Cooperation China 2014
Authors: Li J. , Xie S. D. , Zeng L. M. , Li L. Y. , Li Y. Q. , Wu R. R.
Published: July 2015

Abstract. Ambient volatile organic compounds (VOCs) were measured using an online system, gas chromatography–mass spectrometry/flame ionization detector (GC-MS/FID), in Beijing, China, before, during, and after Asia-Pacific Economic Cooperation (APEC) China 2014, when stringent air quality control measures were implemented. Positive matrix factorization (PMF) was applied to identify the major VOC contributing sources and their temporal variations. The secondary organic aerosols potential (SOAP) approach was used to estimate variations of precursor source contributions to SOA formation. The average VOC mixing ratios during the three periods were 86.17, 48.28, and 72.97 ppbv, respectively. The mixing ratios of total VOC during the control period were reduced by 44 %, and the mixing ratios of acetonitrile, halocarbons, oxygenated VOCs (OVOCs), aromatics, acetylene, alkanes, and alkenes decreased by approximately 65, 62, 54, 53, 37, 36, and 23 %, respectively. The mixing ratios of all measured VOC species decreased during control, and the most affected species were chlorinated VOCs (chloroethane, 1,1-dichloroethylene, chlorobenzene). PMF analysis indicated eight major sources of ambient VOCs, and emissions from target control sources were clearly reduced during the control period. Compared with the values before control, contributions of vehicular exhaust were most reduced, followed by industrial manufacturing and solvent utilization. Reductions of these three sources were responsible for 50, 26, and 16 % of the reductions in ambient VOCs. Contributions of evaporated or liquid gasoline and industrial chemical feedstock were slightly reduced, and contributions of secondary and long-lived species were relatively stable. Due to central heating, emissions from fuel combustion kept on increasing during the whole campaign; because of weak control of liquid petroleum gas (LPG), the highest emissions of LPG occurred in the control period. Vehicle-related sources were the most important precursor sources likely responsible for the reduction in SOA formation during this campaign.
Diurnal aerosol variations do affect daily averaged radiative forcing under heavy aerosol loading observed in Hefei, China
Authors: Wang Z. , Liu D. , Wang Y. , Wang Z. , Shi G.
Published: July 2015

Abstract. A strong diurnal variation of aerosol has been observed in many heavily polluted regions in China. This variation could affect the direct aerosol radiative forcing (DARF) evaluation if the daily averaged value is used as normal rather than the time-resolved values. To quantify the effect of using the daily averaged DARF, 196 days of high temporal resolution ground-based data collected in SKYNET Hefei site during the period from 2007 to 2013 is used to perform an assessment. We demonstrate that strong diurnal changes of heavy aerosol loading have an impact on the 24-h averaged DARF when daily averaged optical properties are used to retrieve this quantity. The DARF errors varying from −7.6 to 15.6 W m−2 absolutely and from 0.1 to 28.5 % relatively were found between the calculations using daily average aerosol properties, and those using time-resolved aerosol observations. These errors increase with increasing daily aerosol optical depth (AOD) and decreasing daily single-scattering albedo (SSA), indicating that the high temporal resolution DARF data set should be used in the model instead of the normal daily-averaged one, especially under heavy aerosol loading conditions for regional campaign studies. We also found that statistical errors (0.3 W m−2 absolutely and 11.8 % relatively) will be less, which means that the effect of using the daily averaged DARF can be weakened by using a long-term observational data set.