Volume 30(2) 2018
Table of contents
|1.||Generation of Artificial Road Profile for Automobile Spring Durability Analysis
Kong Yat Sheng, Shahrum Abdullah*, Mohd Zaidi Omar, Sallehuddin Mohamed Haris & Dieter Schramm
This paper presents the use of a generated artificial road profile in the simulation of a quarter car model for spring durability based-force extraction. In situ measurement of the road loading profile for automotive spring durability analysis, requires considerable cost and effort due to the complex experimental setup. Hence, an artificial road profile was generated for the quarter car model simulation to obtain the spring force signals. Initially, according to the ISO 8608 standard, a class “A” artificial road profile was generated using a designated waviness value, unevenness index and random phase angle. The generated road profile was used as the input to a constructed quarter car model to obtain the spring force signals. Subsequently, the generated nominal force signal was used to predict the fatigue life of the spring. Moreover, to obtain the localise fatigue behaviour of the spring, a finite element spring model together with the force signal was used for fatigue prediction. Under this class “A” road excitation, the spring possessed very high fatigue life of
Keywords: Artificial road profile; quarter car model, strain life approach, fatigue life.
|123 – 128|
|2.||Ground Defected Planar Super-wideband Antenna: A Suitable Transceiver for Short Distance Wireless Communication
Rezaul Azim* & A. K. M. Ariful Haque Siddique
A planar microstrip patch super-wideband antenna is presented for short distance wireless communication applications. The antenna is comprised of a simple patch and a ground plane and etched on two sides of a 1.6 mm-thick standard FR4 substrate material with a relative permittivity of 4.5 and loss tangent (0.02). The proposed antenna possesses a compact size of 29 × 20.5 mm2 with an electrical dimension of 0.25 λ × 0.18 λ. To enhance the operating bandwidth, the ground plane is modified by adding seven small rectangular slots on its upper side. Through numerical studies, it is found that insertion of the slots enhances the coupling between the patch and ground plane resulting in achievement of a super-wide operating band. From the measurements, it is observed that the fabricated prototype antenna has a bandwidth from 2.63 to more than 18 GHz, a symmetric omnidirectional radiation characteristic and the maximum peak gain of 5.85 dBi which makes it a suitable transceiver for short distance communication applications.
Keywords: Antenna; defected ground plane; microstrip patch; transceiver; wireless communication.
|129 – 139|
|3.||The Soft Story Challenge to Architectural Design in Earthquake-Prone Areas
Livian Teddy*, Gagoek Hardiman, Nuroji & Sri Tudjono
The stiffness of irregular configurations/soft storeys is the most frequent cause of structural failure in the irregular vertical part of a building when major earthquakes occur in Indonesia, leaving behind many victims. Soft storeys occur because the first floor of a building is usually more flexible than the other floors. When a strong earthquake occurs, the more flexible storey is not strong enough to withstand the force of the earthquake, and it will cause the building to break and collapse. This paper attempted to address the structural failure of the soft storey, particularly in Indonesia, with regard to its causes, and to find ways to evaluate it and to overcome it through architectural designs. Therefore, this can be taken into consideration by architects in their designing process. The research involved a literature review of topics on soft storeys from existing books and researches. Based on the study, the occurrence of soft storeys in Indonesia is due to inadequate shear column capacity, the presence of a weak storey, a significant difference in wall densities between the floors, the use of materials with different degrees of stiffness in the main structure, structural ductility and poor construction. To reduce the potency of soft storeys, several things can be done by architects in their designing processes such as avoiding direct contact between brick walls, columns and beams, increasing the shear capacity of columns by 2.5 times the normal calculation, using shear walls on the first floor, installing bracings and using seismic insulations
Keywords : soft story, stiffness irregularity configuration, weak story.
|141 – 151|
Bashir Olufemi Odufuwa*, Nathaniel Oluwaseun Ogunseye, Umar Obafemi Salisu & Simeon Oluwagbenga Fasina
Globally, cities are known to be the engines of development. Meanwhile, the failure of most Nigerian cities to satisfy the needs of city dwellers has increasingly become an issue of discourse in recent times. These inadequacies have been blamed on the unguided urbanization rate in most developing countries. Population
Keywords: Cities; Satisfaction; Governance; Insane; Urban management.
|153 – 160|
|5.||Effects of Sodium Sulfate and Sodium Chloride for Sonochemical Degradation on 1,4-benzoquinone and Hydroquinone in Aqueous Solution
Md. Helal Uddin* & Kenji Okitsu
1,4-benzoquinone, with the molecular formula C6H4O2, is generally known as a para-quinone. It is a six-member ring compound with an oxidized derivative known as 1,4-hydroquinone, which is a bright yellow crystal that has an irritating odour. On the other hand, hydroquinone, also known as benzene-1,4-diol, has the chemical formula C6H4(OH)2. It looks like a white granular solid. Quinone is generally used as a precursor to hydroquinone. The skeletal muscle relaxant, ganglion blocking agent, benzoquinonium, is made from benzoquinone. It is utilized to suppress double-bond migrations during olefin metathesis reactions. 1,4-benzoquinone is also used in the synthesis of Bromodol, while hydroquinone is the main ingredient in black-and-white photographic developers such as film and paper developers, where it diminishes the silver halide to elemental silver. There are various other uses related to this diminishing power. As a polymerization inhibitor, hydroquinone prevents the polymerization of methyl methacrylate, acrylic acid, etc. Studies have demonstrated the various effects of Na2SO4 and NaCl on the sonochemical degradation of 1,4-benzoquinone and hydroquinone using a 200-kHz sonicator. The highest degradation rate was obtained in the presence of 0.433 M Na2SO4 for 1,4-benzoquinone. After 30 minutes of ultrasonic irradiation, the total concentration of 1,4-benzoquinone decreased to 99% in the presence 0.433 M Na2SO4. Without Na2SO4, the sonochemical degradation rate of 1,4-benzoquinone was 4.5 times higher than that of hydroquinone, whereas in the presence of 0.433 M Na2SO4 under the same conditions the initial reaction rate of 1,4-benzoquinone was increased to become 10.6 times higher than that of hydroquinone. On the other hand, in the presence of NaCl, no effects were observed for the decomposition of hydroquinone but negative effects were clearly observed for the decomposition of 1,4-benzoquinone.
Keywords: 1,4-benzoquinone; Hydroquinone; Na2SO4; NaCl; Sonication.
|161 – 169|
|6.||Evaluation and Analysis of Traffic Flow at Signalized Intersections in Nicosia using of SIDRA 5 Software
Shaban Ismael Albrka Ali*, Rifat Reşatoğlua & Hudaverdi Tozan
Traffic congestion on road networks and signalized intersections have posed significant problems worldwide. One of the significant ways to reduce traffic congestion in cities is by improving the public transportation system. Therefore, it is essential to use advanced software tools to ensure that the current system can be controlled and evaluated. This study was aimed at assessing and analysing the performance of traffic flow at signalized intersections and roundabouts at peak hours in the city of Nicosia (northern part of the island) using the SIDRA INTERSECTION 5 software. It was also aimed at comparing the performance of traffic flow during the morning and evening peak hours at four intersections and two roundabouts. The parameters used to assess the performance of the traffic flow were the level of service, delays and delayed travel speed, performance index, operating cost, fuel consumption, and carbon dioxide emission. It was found that the SIDRA INTERSECTION software was able to give an estimate of the current situation of traffic flow in the city. The results showed that the level of service was low, resulting in low speeds and lots of delays during the evening and morning peak hours. The delay was up to 9318.9 seconds and the fuel consumption was nearly 1431.6 lit/h, while the CO2 emission was up to 3594.7 kg/h.
Keywords: SIDRA intersection 5, Traffic Congestions, Signalized Intersections, Roundabouts and Level of Service.
|171 – 178|
|7.||Adaptive Cancellation of Localised Environmental Noise
Ali O. Abid Noor*, Imad H.M. Al-Hussaini & Salina Abdul SamadAbstract
Noise cancellation systems are useful in applications such as speech and speaker recognition systems where the effects of environmental noise have to be taken into considerations. A robust method for the cancellation of localised noise in noisy speech signals using subband decomposition and adaptive filtering is presented and described in this paper. The subband decomposition technique is based on low complexity octave filters that split the noisy speech input into subsidiary bands. A thresholding technique is then applied to the subbands to determine the presence or absence of environmental noise. This is used to control an adaptive filter which only responds to the noisy parts of the speech spectrum hence localising the adaptation process only on these segments. The Normalised Least Mean Squares algorithm (NLMS) is used for the adaptation process. A comparison with a similar system without localising the environmental noise shows the superior performance of the proposed system. It has been shown to perform better in terms of computational costs and convergence rate when compared to a system that does not take advantage of the information regarding the presence or absence of noise in a specific part of the speech spectrum. More than 35 dB of noise has been eliminated in less iterations than in conventional approach which needs longer time to reach steady state.
Keywords: adaptive filters, noise cancellation, noise localisation.
|179 – 186|
|8.||Optimising Cutinase Enzyme Recovery in Thermo-induced Phase Separation of LS54/DX ATPS by Enhanced Volume Exclusion Effect
Fariza Akmal Abdul Mutalib, Jamaliah Md Jahim*, Abdul Wahab Mohammad & Farah Diba Abu Bakar
Low recovery of cutinase enzyme in water-enriched phase after thermo-induced separation stage of LS54/Dx aqueous two-phase system was improved by enhanced volume exclusion effect in the polymer-water extraction system. It was done by increased the polymer concentration in the polymer-water system. After primary phase
Keywords: Aqueous two phase system (ATPS), thermoseparation, enzyme recovery, volume-exclusion effect.
|187 – 192|
|9.||Determinants of a Pre-Treatment Model in Achieving Economic and Environmental Sustainability in Membrane Desalination
Man Djun Lee*, Sebastian Dayou & Prashobh Karunakaran
Feedwater pre-treatment plays a significant role in the production performance of water desalination operations. This study aims to formulate a pre-treatment model to evaluate the determinants in achieving economic and environmental sustainability. The research is oriented toward the goal of productivity and performance improvement in the water desalination process. The main objective of this study was to better understand the relationship between feedwater pre-treatment and demineralised water production. The secondary objective was to investigate the effect of an ultrafiltration membrane (UFM) on feedwater production performance. Case studies and literature review are included in this paper. Factors that potentially hinder the efficiency and reduce the load capacity of the desalination process include sand, high levels of ionic bond, biomass and colloid materials. These fouling factors could be eliminated efficiently from the feedwater during pre-treatment. Results demonstrated that the contribution of all inputs to achieve targeted pre-treated water quality (SDI < 3) was significant (p < 0.05) except for activated carbon. Investigations of the pre-treatment process have shown that the silt density index (SDI) is reduced by 45% using a UFM. Higher performance in water desalination was achieved through a higher efficiency in the removal of bacteria, sand, biomass and natural organic materials. Economic analysis showed that overall capacity utilization and operating performance had increased by 11%. This study concludes that quality pretreatment is essential for achieving higher performance in membrane desalination operations.
Keywords: Membrane desalination; pre-treatment technology; economic and environmental sustainability.
|193 – 199|
|10.||Biological Treatment of Pb and Zn using Sequencing Batch Reactor
Omar Syah Jehan Elham*, Siti Afifah Muda, Hassimi Abu Hasan & Siti Rozaimah Sheikh Abdullah
Effective wastewater treatment is essential to prevent water resources from being polluted. Usually, wastewater treatment can be divided into three distinct types; physical, chemical and biological treatment. This research aims to biologically treat Pb and Zn using the Sequencing Batch Reactor (SBR) system. There were four stages involved in the operation of SBR, which include; filled, react, settle and draw. The dissolved oxygen (DO) was controlled in the range of 2-5 mg/L, while the pH was maintained at the range of pH 6.5-7.5. Synthetic wastewater was used as influent with a C:N tested, which were 8, 24 and 48 hrs respectively. Additionally, the water quality parameters analysed were (chemical oxygen demand) COD, ammonium, mixed liquor suspended solid (MLSS) and heavy metal Pb and Zn in the effluent. The average percentage of COD removals in this research was 66.0 % while the average heavy metal removal for Pb and Zn were 97.1 % and 94.7 %, respectively. Therefore, based on the three hydraulic retention times,
Keywords: Sequencing Batch Reactor (SBR), Pb, Zn, Heavy metal wastewater, Biological treatment.
|201 – 207|
|11.||Vortex Measurement at Bell-Shaped Pump Inlet Using Particle Image Velocimetry
Muhammad Azhar Akbar Batcha, Tajul Ariffin Norizan, Zulkhairi Zainol Abidin, Wan Hanna Melini Wan Mohtar & Zambri Harun*
The vortex formed at the pump intake is known to be the main factor affecting the performance of a pump and it contributes directly to the increase of energy consumption. This study was aimed at obtaining an in-depth visualization and identifying the characteristics of the vortices generated by the installation of a bell-shaped suction inlet in a pump-induced flow using particle image velocimetry (PIV). A complementary metal-oxide semiconductor (CMOS) camera was used to capture images of the illuminated bubbles in a sump pump model. The PIV images were analysed using PIVlab, which provided representations of the 2-D plane velocities and vorticities around the inlet of the pump. The measurements were taken at four different planes that were coaxial with the bell circumference below the bell inlet. The results showed that the diameter of the vortex structure became smaller as it approached the bell inlet. Higher values of vorticity were observed within the vortex core, which conformed to the characteristics of a vortex formation. The velocity profiles exhibited the proportionality of the velocity against the radius of the vortex, which categorized this as a forced vortex. The findings from the study will be utilized by the Department of Irrigation and Drainage (DID) Malaysia to develop remedial measures for problems related to the formation of vortices in sump pumps.
Keywords: Particle image velocimetry (PIV); Submerged vortex.
|209 – 217|
|12.||Preliminary Study of Alkaline Direct Ethanol Fuel Cell by using Crosslinked Quaternized Poly (Vinyl Alcohol)/Graphene Oxide Membrane
Zulfirdaus Zakaria*, Norazuwana Shaari & Siti Kartom Kamarudin
OA crosslinked of Quaternized Poly (vinyl alcohol)/Graphene oxide (QPVA/GO) composite membrane was prepared via quaternization and solution casting method. With the main objective is to performed lower ethanol permeability membrane than Nafion 117 membrane thus can be the potential alternative membrane in future. The physical and chemical properties of the QPVA/GO membrane were investigated via the Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction analysis (XRD) and Filed Emission Scanning Electron Microscopy (FESEM). The characterization result shows the good interaction of matrix polymer, GO loading and glutaraldehyde as a crosslinked agent. A maximum conductivity of 1.08 × 10-2 S cm-1 was obtained for QPVA/10wt% GO membrane at 30oC. The ethanol permeability has been reduced until 2.2 × 10-7 cm2 s-1 with increasing of 10 wt.% GO loading which was lower than Nafion 117 (19.5 × 10-7 cm2 s-1). The increasing of GO content in composite membranes has append the hydrophobic region which play role as blocking effect to hinder the ethanol crossover. The cell voltage and power density were analyzed at the temperature 30ºC. A maximum power density achieved by QPVA/GO membrane was 6.92 mW cm-2 at 10.wt% GO loading which higher than Nafion 117 with only 5.07 mW cm-2 using 2 M ethanol + 2 M KOH at 30oC.
Keywords: Quaternized Poly (vinyl alcohol), Graphene oxide, alkaline–DEFC, Nafion 117.
|219 – 227|
|13.||Charge-Discharge Characteristics Improvement Through Optimization of Voltage Range for LiNiCoMnO2 Electrode for High Energy Density LithiumIon Batteries
Puteh Melor Wesma Salehen, Halim Razali, Kamaruzzaman Sopian & Mohd Sukor Su’ait*
The development of suitable electrode materials for lithium ion batteries (LIBs) to enhance the performance of LIBs in order to meet increasingly demand globally is one of the challenges. Thus, for almost three decades since 1980, continuous study for high performance LIBs electrode has been done. In this report, the optimization charge-discharge characteristic of LiNiCoMnO2 (LNCM) cathode – layered structured material with lithium metal as anode has been evaluated. The electrode was assembled together with Celgard as separator and organic electrolyte Lithium hexafluorophosphate (1M LiPF6, EC:DEC 1:1) in coin cells (CR2032) under argon atmosphere inside a glove box. The charge-discharge performance test was conducted using Neware battery testing system. The discussion in this paper is focusing on the characteristic features of the charge-discharge profile, optimize charge-end voltage and rate capability (C-rate). The studies discovered the voltage range has been optimized up to 3.3–4.5 V at a constant current of 0.35 mA (0.1 C) with voltage plateau of 4.0 V. The result indicated the optimized range has the highest specific capacity of 118 mAh/g and most stable coulombic efficiency (94.3 %).
Keywords: Battery; Charge-discharge; Lithium-ion; LiNiCoMnO2; Power capacity.
|229 – 234|
|14.||Kinect-Based Human Gait Recognition using Locally Linear Embedded and Support Vector Machine
Rohilah Sahak, Nooritawati Md Tahir*, Ahmad Ihsan Mohd Yassin & Fadhlan Hafizhelmi Kamaruzaman
Recognition of human gait could be performed effectively provided that significant gait features are well extracted along with effective recognition process. Thus, the gait features should be selected or optimized appropriately for optimal accuracy during recognition. Therefore, in this research, optimization of gait features for both oblique and frontal view are evaluated for recognition purpose using Locally Linear Embedded (LLE) along with multi-class Support Vector Machine (SVM). Firstly, dynamic gait features for one gait cycle are extracted from each subject’s walking gait that is acquired using Kinect sensor. Next, the extracted gait features were then optimized using LLE known as DG-LLE and further classified by multi-class SVM with Error Correcting Output Code (ECOC) algorithm. Further, to validate the effectiveness of LLE as optimization technique, the proposed method is then compared with another two gait features namely the original gait features known as DG and optimization using Principal Component Analysis labeled as DG-PCA. Results showed that the optimization based on DG-LLE outperformed the other two methods namely DG and DG-PCA for both oblique and frontal views. In addition, DG-LLE method contributed as the highest recognition rate for both frontal and oblique views. Results also confirmed that the accuracy rate for frontal view is higher specifically 98.33% as compared to oblique view with 94.67%.
Keywords: Frontal gait recognition; Kinect; Locally linear embedded; Support vector machine.
|235 – 247|
|15.||Synthesis and Characterization of ZnO-decorated GO Nanocomposite Material with Different ZnO Loading through Sol-gel Method
Nurul ‘Adilah Rosnan, Teow Yeit Haan & Abdul Wahab Mohammad
This work aimed is to synthesis a well dispersed zinc oxide (ZnO) nanoparticles (NPs) decorated on graphene oxide (GO) nanosheet with a practical way by using sol-gel technique. Zinc acetate dehydrate (Zn(CH3COO) 2·2H2O) was used as precursor of ZnO and absolute ethanol as solvent. 1 weight percent (wt%), 5 wt%, 10 wt%, and 20 wt% of ZnO was decorated on GO nanosheet. A series of analysis was carried out to characterize the synthesized ZnO-decorated GO nanocomposite material. The results of XRD analysis show some long area of peak at 25º to 80º allocate for ZnO in the ZnO-decorated GO nanocomposite material. By performing zeta potential analysis, the findings show that there was increment of negative surface charge on ZnO-decorated GO nanocomposite material. The experiment result also found that the hydrodynamic particle size of ZnO-decorated GO nanocomposite material become larger when high ZnO loaded. FESEM micrographs demonstrated that spherical-shaped of ZnO NPs appeared on the GO nanosheet with further proved by EDX where the content of ZnO-decorated GO nanocomposite material was composed by 71.3 wt% of C, 17 wt% of O, and additional element of 11.7 wt% of Zn. Thus, it can summarize that the synthesized ZnO-decorated GO nanocomposite material was high in purity. The findings in this study proved that ZnO NPs loading in ZnO-decorated GO nanocomposite material were successfully synthesized by sol-gel method. A ZnO-decorated GO nanocomposite material with layering ZnO NPs on GO nanosheet was produced.
Keywords: Sol-gel; Zinc oxide; Graphene oxide; Nanoparticles.
|249 – 255|
|16.||Kajian Mikrostruktur Aloi Aluminum A390 Selepas Pemesinan Kisar
Kamal Othman*, Jaharah A. Ghani, Che Hassan Che Haron, Afifah Juri & Mohd Shahir Kassim
Aluminium alloy has been receiving a lot of attention from the automotive industry due to its lightweight characteristic that can lead to a reduction in fuel consumption. It is a well-known fact that light components made from aluminium alloy are more cost effective when it comes to the manufacture of block engines and pistons than those made from steel. Among the aluminium alloy fabrications that have grabbed the attention of researchers are alloy mould casting with 9.5 wt.% Si (383), alloy sand mining with 18.5 wt.% Si (A390) and alloy spraying with 25 wt.% Si (Al-25Si). Alloy 390 is suitable for replacing metal cast components due to its higher silicon content, which can help to reduce heat expansion and has good corrosion characteristics. This research presents an observation of the microstructure of aluminium alloys after the machining process. The cutting parameters used were a cutting speed of 250-350 mm/min, feed rate of 0.02-0.04 mm/tooth, and radial width of cut of 12.5 mm – 25 mm. while the depth of cut was kept constant at 0.3 mm. The machining process was carried out under dry and cryogenic conditions. The resultant observation of the microstructure showed the effects of the heat generated during the cutting process at a cutting speed of 350 m/min, feed rate of 0.02 mm/tooth and radial width of cut of 12.5 mm under dry conditions with a worn cutting tool, while for the other cutting parameters, no effects from the heat were observed. No changes in the microstructure were observed through the use of the stated cutting parameters. This showed that the temperature generated during the cutting process was low, and thus, did not cause any changes to the microstructure within the range of the studied cutting parameters.
Keywords: Aluminium Alloy A390; Microstructure; Effect of Heat; Milling Process.
|257 – 264|
|17.||Pengawasan Beban Tak Mengganggu Menggunakan Mesin Penyokong Vektor
Khairuddin Khalid*, Azah Mohamed, Ramizi Mohamed & Nor Azwan Mohamed Kamari
This paper presents the development of non-intrusive load monitoring (NILM) to identify loads using the multioutput support vector machine (MOSVM). A supervised load monitoring method is applied to identify three types of loads that are typically used in commercial buildings such as fluorescent light, air conditioning and personal computers. The basic power parameter provided by the smart meter and other details of the extracted power parameters are considered in this paper. Effective power features are determined by selecting appropriate feature combinations and also, a new feature extraction technique, named ‘time-time’ transformation has been used in this study. A systematic selection of the power parameter is carried out, in this case, to find the best combination for comparison purposes. In the case of commercial smart meter usage for the end-user sector, which is the majority in the low sampling rate, an experiment and studies have been employed under the condition of real power measurement with a low sampling rate. The low sampling rate suitable for NILM is evaluated according to the specification of the commercial smart meter with three conditions of the sampling rate; 1 min, 10 min and 30 min. A set of validation data with random load activities was used to test the effectiveness of the developed NILM method. Further, the load classification technique of MOSVM was used to compare with other techniques such as naive Bayes and KNN to evaluate the performance of the proposed MOSVM for NILM. The results using the proposed MOSVM method showed the best result with an accuracy of 99.94 % in identifying the load. Therefore, based on the sampling rate studied, 1 min sampling showed the best results for the implementation of load monitoring compared to the other sampling rates for NILM.
Keywords: load monitoring; TT-transform; Vector support machine.
|265 – 273|
|18.||Pembentukan Mikrostruktur Berbentuk Sfera Dalam Keadaan Separa Pepejal Aloi Aluminium Al4.8Si2.8Cu-0.5Mg
Mohd Anif Mohd Arif*, Mohd Zaidi Omar & Zainuddin Sajuri
This paper presents the outcomes of the work on the formation of spheroidal microstructure in the semisolid state of Al-4.8Si-2.8Cu-0.5Mg aluminium alloy. The starting material of the aluminium alloy was produced employing a conventional casting process. The microstructure of the starting material consists of fine dendritic and interdendritic structures. The fine nondendritic microstructures of the alloy were generated from the cooling slope casting process. The starting material was initially melted using a resistance furnace before pouring (at 650 °C) onto the cooling slope plate (with 60° tilt angle and cooling slope length of 400 mm) and finally collected in a 150 °C preheated cylindrical stainless steel mould. The formation of the spheroidal structure in a liquid matrix was obtained when the nondendritic alloy billet was rapidly reheated into its semisolid temperature at 575 °C using a high-frequency induction heating system (30-80 kHz, 35 kW). The semisolid alloy billet was successfully thixoformed into a preheated stainless steel die using a hydraulic cylinder press that provided a load of 20 kN with a maximum compression velocity of 85 mm/s. The thixoformed sample showed a uniform distribution of nearly globular α-Al grains without micropores throughout the sample. The results demonstrate that the grain distribution is more homogenous after the T6 heat treatment which involves the solid solution treatment at 480 °C for 8 hrs, quenched in warm water at 60 °C and followed by ageing at 155 °C for 4 hrs.
Keywords: Nondendritic microstructures; Cooling slope casting; Spheroidal structure; Thixoforming; T6 heat treatment.
|275 – 280|
|19.||Sifat Mekanikal Saduran Epoksi Mengandungi Abu Buangan Industri
Nursyahirah Mohd Safie*, Nor Yuliana Yuhana* & Zakaria Man
Organic epoxy coating was the primary focus of this study because of its thermosetting characteristics, high durability of adhesion to the substrate, stable structure, chemical resistance and economical cost. However, epoxy coating has several disadvantages in that it is easily cracked, brittle and sensitive to climate change due to its ability to easily absorb water. Humidity can weaken the structure of the coating. To resolve this issue, fly ash is added as reinforcement to the structure of the epoxy. Fly ash is a material that can improve the mechanical strength and durability of a coating. However, the optimum mass of fly ash in the epoxy should be studied carefully to produce an epoxy coating that is strong, stable and that does not easily absorb water. Therefore, this study was performed to synthesize epoxy resin with fly ash as filler, as well as to analyse the impact of fly ash on the properties of the epoxy coating through hardness strength tests. The characteristics of the epoxy resin with fly ash (MFA and OFA) and without fly ash (RE) were analysed by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and density and particle size analysis. Based on the FTIR analysis, fly ash does not change the structure of the functional groups in the epoxy. For the TGA analysis, the onset of degradation for MFA and OFA started to occur at 346 ± 1°C. The addition of 5% fly ash increased the hardness of the epoxy by up to 13% compared to the unmodified epoxy. Epoxy coatings can be improved in terms of their hardness and degradation time by the addition of fly ash as filler.
Keywords: Fly ash; Epoxy resin; Composite.
|281 – 287|
|20.||Kesan Penjana Fotovolta Tersambung-Grid terhadap Kestabilan Voltan Dinamik dalam Sistem Kuasa
Zetty Adibah Kamaruzzaman, Azah Mohamed* & Nor Azwan Mohamed Kamari
The integration of grid-connected photovoltaic (PV) generation into a power system causes certain technical effects because the network design initially does not consider the integration of distributed generation. The rapid growth of PV module installations and high penetration of PV generation can cause many technical issues such as poor power quality and can impact on power system voltage stability. This study focuses on dynamic voltage stability analysis as well as determining the dynamic PV system parameters that affect dynamic voltage stability. The system models developed for dynamic voltage stability analysis consider the dynamic PV generator model and dynamic load. Time-domain dynamic voltage stability simulations consider factors such as intermittent solar radiation, line outage and dynamic load such as the induction motor. Simulations were performed at the maximum level of PV penetration; 2 % for the IEEE 118 bus transmission system and 60 % for the IEEE 69 bus radial distribution system. The results show that intermittent solar radiations due to cloud cover have an impact on voltage stability in the power system. The sudden drop in voltage causes dynamic voltage instability in which the bus voltage drops more than 6 % of the allowable voltage deviation. Dynamic disturbances such as starting of the induction motor also affect voltage stability. Notwithstanding, islands are formed due to line outage at the line connected to the PV generator bus. Hence, the presence of the gridconnected PV generator and induction motor cannot help to maintain balancing of the bus voltage which can ultimately lead to voltage collapse.
Keywords: Dynamic voltage stability; Grid-connected photovoltaic systems; Dynamic photovoltaic model.
|289 – 296|