Volume 25 (2013)

Table of Contents

No. Article Detail
1. Penggunaan Bahan Penstabil dalam Kitar Semula Sejuk Setempat Turapan Jalan Raya Boleh Lentur (The Use of Stabilisation Materials in Cold-in Place Recycling of Flexible Pavement)
Asmah Hamim & Nur Izzi Md. YusoffAbstract
This study was conducted to investigate the effectiveness of using silica fume, rice husk ash and lime as stabilisation materials in the cold-in-place recycling of flexible pavement. The cold-in-place recycling sample consists of 75% of recycling asphalt pavement taken from the site, 25% of crushed run and 5.05% of water. Asphalt mixture added with 1.5% cement (by total weight of a sample) was used as a control sample. Meanwhile silica fume, rice husk and limestone were added to samples at different percentages of 1, 3, 5, 7 and 9%. Five different tests; namely compaction test using vibrating hammer, Marshall Stability and Flow tests, unconfined strength test, indirect tensile modulus test and static creep test were conducted. It was found that all the stabilisation materials show inconsistent results compared to the 1.5% cement mixture. However, the use of 7% of rice husk shows good potential as a stabilisation material because of its strength, better withstand for higher loads and higher creep resistance compared to the silica fume and limestone mixtures. The results also showed that the optimum content of silica fume and limestone are 7% and 3% respectively to produce good cold-in-place recycling mixture.
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2. Power Quality Improvement in Distribution Systems Considering Optimum D-STATCOM Placement
Masoud Farhoodnea, Azah Mohamed, Hussain Shareef & Hadi ZayandehroodiAbstract
This paper presents an improved method in solving the optimization problem related to the optimum placement and sizing of the Distribution Static Synchronous Compensator (D-STATCOM) in distribution systems, which use the firefly algorithm (FA) for power quality improvement. In the proposed method, the voltage total harmonic distortion, voltage deviation, and total investment cost indices are considered as the problem sub-objective functions. The voltage and power limits for individual buses are considered as the constraints to control optimization variables. The proposed FA is implemented using the Matlab software on modified IEEE 16- and 34-bus test systems. The obtained results are compared with the particle swarm optimization and the genetic algorithm. The simulation and comparison results verify the ability of the FA to accurately determine the optimal location and size of the D-STATCOM in radial distribution systems.
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Analisis Kesan Frekuensi dan Sudut Dongakan terhadap Pelemahan Hujan di Malaysia (Frequency Effects and the Elevation Angle Analysis of the Rain Attenuation in Malaysia)
Teh Sieh Ting, Ooi Wei Chun & Mandeep J.SAbstract

Congestion on frequency spectrum that was predetermined long time ago has stimulated the use of frequency above than 10 GHz in order to fulfil the needs and requirements of the customers. However, operating at this frequency band will cause the system to be more easily susceptible to signal loss due to natural phenomena such as heavy rain. Because of the fading effects, accurate prediction of rain induced attenuation by using 1-min rainfall rate becomes important. Many researchers have proposed various types of predictive models to estimate the rain attenuation over the world. However, there is no appropriate model that can predict the rain attenuation accurately. At Universiti Sains Malaysia (USM), the International Telecommunication Union model-Region (ITU-R) has shown the best prediction compared to other models. ITU-R model is used to analyze the effects of rain attenuation at different frequency and elevation angles. From the analysis, it was found that as the frequency of operation increases and the angle of elevation reduces, this would result in an increase in rain attenuation. However, the above clarification may be seen for elevation angles above 50° elevation.
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4. Comparison between Mixtures of Asphalt with Palm Oil Shells and Coconut Shells as Additives
Ramez A. Al-Mansob, Amiruddin Ismail, Mohammed A. Algorafi, Mohammad Hesam Hafezi & Mojtaba Shojaei BaghiniAbstract
The finding of other alternative material that has become the concern of various works lies in the fact that the material is to serve as an additive in asphalt mixes to enhance its physical properties. This paper deals with a laboratory study which compares the performance of hot mix asphalt (HMA) with the use of palm oil shells (POS), also with coconut shells (CS) as an additive and control samples. Both the palm oil shells and coconut shells are put in separately, taking up the shape of coarse aggregate with the size of 4.75 mm. The amount of these palm oil shells and coconut shells blended into the mixes is expressed in respective percentage (0,5, 10, 15 and 20%) of the total weight of the size 4.75 mm of aggregate. The Superpave method was employed to design the mixes. Samples were prepared and put to the test for the rutting characteristic as the indicator to the performance examined. It was observed that the addition of the coconut shells has made the HMA better with respect to their resilient modulus under 40˚C of temperature, it is cleared that 20% of CS as additive is the best percentage in term of resilient modulus among the percentages that have been chosen. However, it is contrary for the POS. The POS and CS addition will lead to that the asphalt concrete becoming more responsive to permanent deformation (static and dynamic creep) for more than 5% of shells content. In general, the CS emerges as better additives than POS in the HMA.
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5. Pemetaan dan Pengelompokan Isyarat Akustik Alat Muzik Tradisional Melayu Menggunakan Kaedah Analisis Isyarat Statistik (Mapping and Clustering of the Acoustic Signal of Malay Traditional Musical Instruments using Statistical Analysis Method)
Abdul Rahim Bahari, Mohd Zaki Nuawi, Ab Samad Kechot, Firdaus Mohd Hamzah & Suziana Mat SaadAbstract
This paper discusses the development of a method for mapping and clustering acoustic signal of traditional Malay musical instruments. The acoustic signal for knot B3 has been recorded using a sound recording system which has been designed based on the combination of a microphone, a power module and a data acquisition system. The Malay traditional musical instruments involved are cak lempong, flute and gambus. The recording in the time domain shows a variety of waveforms according to the instrument’s method of play. The level of similarity between two different acoustic signals of same traditional Malay musical instrument has been determined by ANOVA analysis. For the mapping and clustering process, alternative methods of statistical signal analysis known as Integrated Kurtosis-based Algorithm for Z-notch Filter (I-kaz™) and Mesokurtosis Zonal Nonparametric (M-Z-N) has been applied to extract the signal’s features. Identification is done using a combination of I-kaz and M-Z-N coefficients. The result shows that the characterization of acoustic signals of traditional Malay musical instruments through mapping and clustering has been successfully implemented by this developed method.
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6. Design of Microstrip Line-Coupled Isosceles-Triangular Loop Resonator Antenna
Seyi Stephen Olokede, Mohd Fadzil Ain, Mohammed Ariff Othman, Ubaid Ullah & Zainal Araffin AhmadAbstract
In this paper, an experimental study on a microstrip line proximity coupled triangular microstrip loop resonator antenna is presented. The antenna is fed by a 50 Ω microstrip feed line arrangement at the frequency of 5.8 GHz. The antenna element is placed at λg /4 from the stub, and λg /2 away from the feed based on the voltage allocation on an open ended transmission line where λg is the guided wavelength. The antenna element was rotated 90 degree clockwise about the z-axis in parallel with the microstrip feed. This was done in order to 1) ensure a good proximity coupling, and 2) to indicate that the amount of coupling from the microstrip line to the resonator can be controlled to a certain degree by adjusting the spacing. A similar design was done without rotating the resonator, and the result is reported. It was observed that the measured |S11| of the rotated element is superior to the un-rotated by 43.75%, and 40.43% for the simulated. In all, experimental results agreed significantly with simulated results.
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