Skip Navigation LinksVolume : Volume 15 No.2 2006

  
  
  
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voltage_sag_mitigation_due_to_starting_of_an_induction_motor_load.pdfVOLTAGE SAG MITIGATION DUE TO STARTING OF AN INDUCTION MOTOR LOAD
  
ABSTRACT :
Power quality is one of the most talked about topics these days. Both the  power utilities and customers are quite concerned with the quality of the power supply, whether it be the power generated by the power utilities or the power consumed by the   customers respectively. They need these supplies to be at its optimum value so that the  cost is efficient; otherwise problems such as overvoltage, undervoltage, voltage swell, voltage  sag, noise and harmonic caused by the disturbances in power supply could be disastrous.  This paper investigates the static synchronous compensator (STATCOM) behaviour for voltage sag mitigation due to starting of an induction motor. Simulation of STATCOM based   on 6 pulses 3-phase voltage source inverter (VSI) using Matlab Simulink has been   developed to show its performance under balanced voltage sag condition due to starting    of 5 KW 3-phase induction motor. Experimental testing has been constructed using 3-phase thyristor natural commutation  bridge. An improvement of more than 11% of the voltage sag has been achieved using the STATCOM which can respond instantaneously to compensate reactive power to the system during voltage sag. Finally simulation results and experimental results have been explained and compared, and a good performance has been obtained.       

KEYWORDS : Voltage sag, sag mitigation, STATCOM, Var compensation               

Author: S.M. Bashi, N. Mariun, N.F. Mailah, A.F. Huweg
Year: 2006
studies_on_metal_leachability_and_alkalinity_of_leachates_from_cement_stabilised_contaminated_soils.pdfSTUDIES ON METAL LEACHABILITY AND ALKALINITY OF LEACHATES FROM CEMENT STABILISED CONTAMINATED SOILS
  
ABSTRACT :
This paper presents the findings on zinc and lead leachabilty as well   as alkalinity of leachates from cement stabilised contaminated soils. The Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) have been performed on the solidified/stabilised contaminated   soils of which zinc and lead concentrations and alkalinity of the resultant leachates are determined. Results indicate that cement shows excellent treatment effectiveness for stabilising metal contents in contaminated soil. It has also been determined that   the residual blocks of stabilised contaminated soil present in unfiltered leachates provide additional acid buffering capacity to the leachates, reducing the leached   concentrations of zinc and lead.       

KEYWORDS : pH, alkalinity, solidification/stabilisation, lead, zinc, cement

Author: Yin Chun-Yang, Hilmi Bin Mahmud and Ghazaly Shaaban
Year: 2006
preliminary_studies_on_the_heat_treatment_processes_for_pan_carbon_fibre.pdfPRELIMINARY STUDIES ON THE HEAT TREATMENT PROCESSES FOR PAN CARBON FIBRE
  
ABSTRACT :
This paper reports the preliminary studies of pre-stabilisation and stabilisation processes in the production of PAN carbon fibre. The pre-stabilisation process involves   immersion of PAN precursor in potassium permanganate (KMn04), dimethylformamide (DMF) and aluminium chloride (Al2Cl6) at 85°C in which a promising catalytical behaviour is   demonstrated through the characterisation techniques used. The Fourier Transform Infra   Red (FTIR) spectra indicate a distinctive nitrile group of C=N at 2350 cm-1 and a decrease of   C=N group at 2244 cm-1 during pre-stabilisation process. This is due to the formation of a ladder polymer which occurs intermolecularly or intramolecularly during cyclisation process. Thermal analysis supports this view as the pre-treated PAN fibre showed a reduced activation   energy, earlier onset cyclisation temperature and higher degree of cyclisation reaction through   its heat flow. Similarly, stabilisation at 200°C also indicates chemical structural changes   through cyclisation process. Various competing reactions took place during stabilisation. Cyclisation results in the release of a few gaseous species such as HCN and C02 while   oxidation possibly results in the absorption of O2 into the PAN precursor backbone.       

KEYWORDS: PAN carbon fibre, pre-stabilisation, thermal stabilisation, heat treatment   

Author: M.A. Baharom, S. Shamsuddin, I. Mustafar, K. Noorsal, I. Ahmad, H.F.A. Marzuki
Year: 2006
practice_of_critical_factors_for_business_survival_and_competitiveness_in_malaysian_manufacturing_smes.pdfPRACTICE OF CRITICAL FACTORS FOR BUSINESS SURVIVAL AND COMPETITIVENESS IN MALAYSIAN MANUFACTURING SMEs
  
ABSTRACT :
This paper is based on a survey conducted in 2003 on top management's  practice of critical factors for business survival and competitiveness in the Malaysian automotive components manufacturing   SMEs. The main objective of this paper is to provide   empirical evidence on top management's practices of the critical factors. To achieve this   objective, the authors developed a questionnaire comprising four major critical factors and  53 elements that was checked for reliability and validity by experts and practitioners. The analyses from 68 respondent companies showed overall, there are some very important factors that could influence the SMEs competitive performance relative to competitors and   their goals to survive, stay competitive and prosper. The paper also discusses the critical   factors, major problems and obstacles for implementing benchmarking activities. Finally,   the paper concludes with some suggestions on steps to improve the adoption and practice   of critical factors for improving business performance and competitiveness in Malaysian   SMEs.       

KEYWORDS : Business competitiveness, survey, critical factors, customer satisfaction,  and SMEs           

Author: Baba Md Deros, Sha\'ri Mohd Yusof and Azhari Md Salleh
Year: 2006
metals_in_medical_and_dental_surgery.pdfMETALS IN MEDICAL AND DENTAL SURGERY
  
ABSTRACT :
Metals have been successful biomaterials for many years,         especially for medical and dental surgery purposes. The most common metals are stainless steel, cobalt-chromium alloys, and titanium and its alloy. The mechanical properties of the materials are of great importance when designing   load-bearing implants. The properties of the implants depend not only on the   type of metal but also on the process used to fabricate the material and device.   In addition, its must be either noble or corrosion-resistant to the body environment.  The purpose of this contribution is to briefly discuss their properties, compositions,   processing and applications.       

KEYWORDS : Metal implant, titanium, stainless steel, cobalt chrome

Author: Mohmad Soib bin Selamat
Year: 2006
mechanism_of_grain_growth_in_an_aerospace_aluminum_alloy.pdfMECHANISM OF GRAIN GROWTH IN AN AEROSPACE ALUMINUM ALLOY
  
Abstract :
Annealing heat-treatments experiments in the temperature range of 200-250°C for durations in the range of 20 min - 22h for the aerospace aluminum alloy have been conducted. The material processing resulted in grain growth in the microstructure of the alloy. The grain size data have been plotted versus   time at various temperatures; and the graphical plots have been analysed to  establish the effects of annealing time and temperature on grain size. A distinction between normal and abnormal grain growth has been made to study the  mechanism of the grain growth processes. The rates of grain growth at various  grain diameters have also been computed at various temperatures and graphically analysed to establish the kinetic aspects of grain growth in the aerospace   aluminum alloy.       

Keywords : 2024-T3 aluminum alloy, grain growth, kinetics, normal and  abnormal grain growth          

Author: Zainul Huda, Mohammad Saufi and Shaifulazuar
Year: 2006
implementing_iso_14000_the_key_to_greening_of_malaysian_industry.pdfIMPLEMENTING ISO 14000: THE KEY TO GREENING OF MALAYSIAN INDUSTRY
  
ABSTRACT :
Throughout the world today, the approach is for industries   and governments to respond to increasing public concern on the   environment by adopting appropriate policy and framework for   environmental protection. The emergence and implementation of the ISO   14000 series of standards impose additional costs and generate new   opportunities for Malaysian industries which could change the competitive   climate that faces them in this era of globalisation. The survival and   success in the marketplace is linked to the ability of our Malaysian   industries to be flexible and be able to respond to new pressures before them. This paper highlights the benefits of adopting and implementing the ISO 14000 series of standards where Malaysian industries could make efforts towards environmental improvement and enhance performance. 

KEYWORDS : Environmental management, greening Malaysian   industry, sustainable development environmental management systems,   ISO 14000     

Author: Sumiani Yusoff, PhD.
Year: 2006
implementation_of_process_quality_module_pqm_in_fan_and_blower_plants_shop_floor_reengineering.pdfIMPLEMENTATION OF PROCESS QUALITY MODULE (PQM) IN FAN AND BLOWER PLANT'S SHOP FLOOR REENGINEERING
  
ABSTRACT :
The process quality module (PQM) was used to investigate the flow of production and the incorporated quality shortcomings in fans and blowers industry.   PQM contains seven modules and it outlines all the approaches needed for reengineering . The first three steps are initialisation steps designed to be executed   infrequently. The first step is to identify process, technology, and tasks being performed. The next step is to identify the customers and their requirements, expectations, and   perceptions. The third is to define quality as it pertains to the process of interest. The   last four steps of the PQM are designed to facilitate continuous improvement and process   control, and thus they are executed frequently. It starts by identifying quality performance   measures. Evaluation of the current process and setting of quality standards is followed   by the improvement of the process. Finally the process must be controlled and monitored. PQM approach is interpreted for this industry and necessary modifications are made. The steps and methods used to implement are discussed and recorded . 

KEYWORDS : Process quality module, fan and blower, reengineering            

Author: K.W. Rao, M. Y. Ismail, M. M. Hamdan, N. Ismail, S.M. Sapuan and V. Mariappan
Year: 2006
effect_of_al2o3_addition_in_the_hand_former_composition_on_chemical_resistance.pdfEFFECT OF Al 20 3 ADDITION IN THE HAND FORMER COMPOSITION ON CHEMICAL RESISTANCE
  
ABSTRACT :
Ten compositions of hand former body were prepared   with different alumina content from 1% to 45% to determine the effect  of acid and alkali resistance. The compositions containing alumina   between 20% to 25% showed good resistance to acid and alkali. The  acid resistance (body corroded by acid) is between 16-20 x 10-3 g/cm 2 and the alkali resistance is between 180 - 210 x 1Q-3 g/cm 2• The body was matured at 1250°C for 30 minutes at the firing rate of 3°C/minute. 

KEYWORDS : Hand former, chemical resistant, acid resistant, alkali  resistant     

Author: Jaafar Abdullah
Year: 2006
direct_measurement_of_powder_cohesion.pdfDIRECT MEASUREMENT OF POWDER COHESION
  
ABSTRACT :
Cohesion is a physical property that best describes the flowability of powder which aids in storage, handling and processing of powders. In this study cohesion values are measured and correlated with other established flowability indicators such as angle of repose and Hausner ratio. A series of mixture of fine and coarse sand composition were employed with sauter diameters of 15.21 µm and 636.80 µm respectively. Warren-Spring-Bradford Cohesion Tester (WSBCT) used  for direct measurement was found to be simpler and time saving compared to the conventional indirect method of the Jenike Shear Cell. Cohesion value and penetration  strength were measured with the WSBCT. Established flowability indicators, i.e.   Hausner ratio and angle of repose were measured separately. It was found that a particle size of 45 µm is critical in determining the cohesivity of powders. Cohesion  values correlated well with other known flowability indicators. However, the penetration   strength was found to be a poor flowability indicator for the fine powders used. Recommendations are proposed on how to further investigate the penetration strength of fine powders.       

KEYWORDS : Cohesion, powder, flowability         151       

Author: Aziz A.R. and E.C. Abdullah
Year: 2006
application_of_cad_and_sla_for_design_and_development_of_titanium_mesh_implants.pdfAPPLICATION OF CAD AND SLA FOR DESIGN AND DEVELOPMENT OF TITANIUM MESH IMPLANTS
  
ABSTRACT :
The use of CAD and Rapid Prototyping in surgery has benefited both   surgeons and patients. 20 image data of patients is converted to 3D CAD data for   further manipulation and anatomic models produced by rapid prototyping technique   provide tactile information that can be used by surgeons to diagnose and plan the   treatment and surgical operation. A case study of the application of CAD and RP for   design and fabrication of implant used in craniofacial surgery is described. The result   of this process is the production of a mould that is used to press form titanium mesh   into a ready to use implant, which fits nicely to the patient. The approach has increased   the effectiveness and productivity of surgeons as well as improved the overall surgery   time. 

KEYWORDS : CAD, Rapid Prototyping, Stereolithography, Craniofacial, Surgery, Titanium Mesh Implant            

Author: Wan Abdul Rahman Wan Harun, Victor Devadass, lzhar Abdul Aziz
Year: 2006
activity_and_deactivation_of_cr_cu_modified_zsm-5_catalyst_in_the_combustion_of_chlorinated_volatile_organic_compounds.pdfACTIVITY AND DEACTIVATION OF Cr-Cu/MODIFIED ZSM-5 CATALYST IN THE COMBUSTION OF CHLORINATED VOLATILE ORGANIC COMPOUNDS
  
ABSTRACT :
The performance of chromium-copper supported over H-ZSM-5 (Si/Al=240)   modified with silicon tetrachloride (Cr1_0Cu0/SiCl4-Z) as the catalyst in the combustion of   chlorinated VOCs (CI-VOCs) is reported. A reactor operated at gas hourly space velocity (GHSV)   32,000 h·1, temperature between 100 and 500°C with 2,500 ppm of dichloromethane (DCM),   trichloromethane (TCM) and trichloroethylene (TCE) were used for activity studies. Deactivation   study was conducted at GHSV 3,800 h-1 at 400°C for up to 12 h with a feed concentration of   35,000 ppm. TCM was more reactive compared to DCM but it produced more chlorinated byproducts         due to its high chlorine content. The stabilisation of TCE was attributed to the resonance         effects. The residual activity of this catalyst stabilised at between 88-92%, depending on feed   compounds. Deactivation of Cr1_0Cu0/SiCl4-Z was mainly due to the chlorination of its metal   species, especially with higher CI/H feed. Coking activity of this catalyst was low particularly         with DCM and TCM. In accordance with Mars-van Krevelen model, the weakening of overall         metal reducibility due to chlorination led to loss of activity.  

KEYWORDS : CI-VOC, deactivation, reducibility, ZSM-5, bimetallic, SiCl4 77
       
Author: Ahmad Zuhairi Abdullah*, Mohamad Zailani Abu Bakar and Subhash Bhatia
Year: 2006
a_5.7_ghz_variable-gain_low_noise_amplifier_vglna_for_low_voltage_applications.pdfA 5.7 GHZ VARIABLE-GAIN LOW NOISE AMPLIFIER (VGLNA) FOR LOW VOLTAGE APPLICATIONS
  
ABSTRACT :
A low voltage topology that uses a capacitively coupled resonating  element has been introduced in the ever demanding radio frequency (RF) designs.   The topology utilises the decoupling scheme to de isolate circuit elements that are   connected in series and share a common de current. A 5.7 GHz 0.18 µm CMOS  variable-gain low noise amplifier (VGLNA) is used to realise the topology. Simulation shows promising results with the VGLNA exhibiting a noise figure of 1.02 dB, power gain of 19.41 dB, IIP3 of -1.11 dBm and gain tuning range of 6 dB. The power  consumption reported is 12.88 mW at supply of Vdd = 0. 7 V.A comparison is made   between a low voltage cascode VGLNA and the classic cascode VGLNA. The   results show that the low voltage cascode VGLNA performs better in most areas.     

KEYWORDS : capacitively coupled, linearity, low voltage, power optimisation, variable-gain low noise amplifier       

Author: Lini Lee, S.S. Jamuar, Roslina Mohd Sidek and Sabira Khatun
Year: 2006