ADDRESS

Faculty of Engineering and Built Environment
Universiti Kebangsaan Malaysia

Volume 30(1) 2018

Table of contents

 

No. Article Page  
1. An Optimized Structure for Enhancing Optical Absorption of Solar Energy in Elliptical GaAs Nanowire Array Solar Cell

Nazmus Sakib & Md. Atiqur Rahman Ahad* 
Abstract

The enhanced optical absorption of solar energy in a solar cell using nanostructured materials is a very demanding and important research area. Hence, an optimized structure to increase the optical absorption of solar energy in an elliptical GaAs (Gallium Arsenide) nanowire array solar cell was proposed in this paper. The influence of geometric parameters on the optical absorption of elliptical GaAs nanowire solar cells was investigated by exploiting the finite difference in time domain simulations. Based on the design and analysis, the elliptical GaAs nanowire array performed better than any circular GaAs nanowire. It was found that the enhanced performance was due to the reduced reflection from the top surface and a reduced transmission from the bottom surface of the elliptical GaAs nanowire array. The structural parameters of the elliptical GaAs nanowire were optimized by calculating the short circuit current density (Jsc) for different geometries over the solar spectrum. It was demonstrated that there was an increase of 9.4% in the Jsc compared with the circular GaAs nanowire under the optimized conditions.

Keywords:  solar cell; GaAs; nanowire array; solar energy; optical absorption

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-01
1 – 6
2. Developments in Plasma Arc Cutting (PAC) of Steel Alloys: A Review

Zeki Cinar, Mohammed. Asmael* & Qasim. Zeeshan
Abstract

The Plasma Arc Cutting (PAC) process was developed for difficult-to-machine materials in order to overcome the inefficiency and ineffectiveness of conventional machining methods when it comes to complex shapes and tool wear due to the contact between the tool and the workpiece. PAC consumes ionized gas, known as the heat source, and a high energy stream, known as the plasma. Many researchers have examined the PAC of steel alloys by considering the cutting power, scanning speed, cutting height and plasma gas pressure as the process parameters, and analysing the effects on the edge roughness, the kerf taper angle (conicity), burr formation, Heat Affected Zone (HAZ), Material Removal Rate (MRR), surface quality after cutting, and the metallurgical effects of the cut. A comprehensive review was carried out on developments in the analysis and optimization of PAC for steel alloys. It is observed that, the feed rate and edge roughness have a significant effect on the machining characteristics; however, less consideration was given by the researcher to these parameters. In addition, a critical comparison was made of the process parameters involved and the methods of analysis used, with the aim of providing the status of current research and guidance for future research.

Keywords: Plasma Arc Cutting (PAC); Heat Affected Zone (HAZ); Material Removal Rate (MRR); Steel alloys; Design of Experiments (DOE).

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-02
7 – 16
3. Flow Behavior of 1.4841 Steel in Hot Compression Process

Javad Rajabi*
Abstract

Hot compression experiments using a dilatometer were carried out in order to study the effects of hot compression parameters on the flow behaviour of 1.4841 steel. Specifically, the effects of the strain rate and the deformation temperature within a temperature range of 950–1100oC, strain rate of 0.001-0.5 S-1 and strain value of 0.5 were studied among all the effective hot compression parameters. The results were shown in the actual strain–stress curve. Embedded in the work hardening, recrystallization and recovery theories, the hot compression mechanism was determined by focusing on the flow behaviour patterns of this steel. The sensitivity to strain rate and temperature, activation energy and the Zener–Holloman parameter were also investigated. Critical strains (c) of 0.2 and 0.35 were calculated for strain rates of 0.001 and 0.01 s-1, respectively. The findings showed that the recrystallization and flow stress fell when a deformation was imposed at a low strain rate and high temperature. A further increase in the strain rate and a decrease in the temperature resulted in a dynamic recovery mechanism as the dominant process. With an increase in the temperature, the strain rate sensitivity increased, and the rise in the strain rate resulted in a decrease in the temperature sensitivity. The temperature sensitivity (nª) for various strain rates was estimated more precisely to be within the range of 5.3 to 11.2. The QHW was measured and the value was 459.186 kJ/mol

Keywords : Dynamic recovery; Dynamic recrystallization, Temperature sensitivity parameter; Strain rate sensitivity parameter;
Zener-Holloman parameter.

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-03
17 – 22
4. Pattern of Muscle Contraction in Car Pedal Control

Nor Kamaliana Khamis*, Baba Md Deros, Mohd Zaki Nuawia & Dieter Schramm
Abstract

Driver’s discomfort has gained a lot of attention, especially among interested parties. There are many interacting factors involving both the driver and the interior components of the car that contribute to discomfort while driving. In this study, an investigation was carried out on the contraction of the lower leg muscle among drivers when operating the accelerator pedal. The main objective of this study was to determine the pattern of muscle contraction when operating the accelerator pedal with regard to three different actions; pressing, halfpressing and releasing. Eleven participants were involved in this investigation into the muscle pattern, whereby surface electromyography (SEMG) was used to measure the activity of the lower leg muscle, known as the tibialis anterior (TA). The data collection procedure on the selected muscle was in accordance with the SEMG recommendations for the Non-Invasive Assessment of Muscles. Based on the results, the TA depicted that the highest muscle contraction occurred during the releasing action. In addition, there were significant differences between each action in the T-test analysis with p<0.05. It can be concluded that the TA muscle works differently based on the car pedal actions.

Keywords: Driver; Accelerator pedal; Leg; Tibialis anterior; Electromyography

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-04
23 – 29
5. Carbon Dioxide Adsorption on Activated Carbon Hydrothermally Treated and Impregnated with Metal Oxides

Hazimah Madzaki, Wan Azlina Wan Ab Karim Ghani*, Thomas Choong Shean Yaw, Umer Rashid & Noraziah Muda
Abstract

Activated carbon (AC) has been used widely as an agent for carbon dioxide (CO2) adsorption due to its environmentally friendly nature, low cost, high porous structure, high surface area and good mechanical properties. Modifications have been made to AC in order to enhance its adsorptive properties. In this study, the performance of activated carbon modified by hydrothermal treatment and impregnation techniques was compared using metal oxides. The prepared samples were characterized by different techniques using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption of CO2 was investigated using a CO2 adsorption unit, whereby 20% of CO2 gas was passed through the samples until a breakthrough point was achieved. During the adsorption study, it was found that AC that had been hydrothermally treated with cerium oxide (CeO2) had the highest adsorption capacity of 0.856 mmol/g with a breakthrough time of 19.33 min.

Keywords: Activated carbon; carbon dioxide; hydrothermal; impregnation; metal oxides

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-05
31 – 38
6. Flow Structure in Modern Cities: Wind Tunnel Investigation

Farhana Najwa Azman, Eslam Reda Lotfy, Ashraf Amer Abbas & Zambri Harun*
Abstract

Natural ventilation dominates the heat dissipation and pollutant dispersion in modern cities. Investigations into the flow structure and urban heat island in the Kuala Lumpur City Centre (KLCC) have been conducted by a few researchers. However, these studies were mainly accomplished by means of computational fluid dynamics. The critical problem with computational analysis is the lack of verification. As such, in this research, experimental tools such as the wind tunnel, hotwire anemometry, Pitot tube, and pressure and temperature sensors were utilized. The aim was to assess the ventilation performance of different city models with a height-to-width ratio that was similar to that of the KLCC. Several steps had to be performed before starting the study, among these being the building of the model. A 6×6 array of uniform acrylic blocks (50×50×100 mm) were arranged in line at equal distances. Three arrangements, representing different building densities (35, 25 and 15%), were examined in the current research. The freestream wind speed was fixed at 5 m/s. The flow was found to be comprised of vortical structures, and attained an energetic turbulence in the downstream of the building areas as compared to the free flow areas. This study suggests keeping the plane area ratio in high-rise building cities within a 15-25% range. The study is beneficial to town planners as the construction of more skyscrapers is being planned.

Keywords: Wind flow; Hotwire; Urban environment, KLCC, Turbulence intensity.

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-06
39 – 46
7. Droplets Tracing in a T-junction Microchannel

Nur Tantiyani Ali Othman* & An-Najmi Mohd Farid

Abstract

Emulsions consist of small liquid droplets immersed in another liquid, typically either a mix of oil in water or water in oil. Emulsions have wide applications in the production of pharmaceutical products, food and cosmetics. The properties and quality of an emulsion typically depend on the size and the distribution of the droplets. Thus, the objective of this study was to investigate in detail the formation and behaviour of droplets in a T-junction microchannel. By setting up a model and applying a laminar two-phase flow in ANSYS© simulation, the particle droplets distribution was observed. The model used the predefined wetted wall boundary condition at the solid walls, with a contact angle of 135°. In this study, the behaviour and flow pattern of the particles along the T-junction microchannel were observed with regard to the effect of the initial particle concentration, the flow rate of the particles, and the initial velocity feed through the inlets of the microchannel. From the results, the effects of the velocity, mixing time and flow rate of the particles on the particle distribution and mixing were studied. It was shown that the optimization process was achieved at a flow rate of 0.025 mL/s, with the mixing process occurring within 1.6 seconds and the velocity feed at the two inlets being VA=0.02 m/s and VB=0.04 m/s, where the particles experienced less lift shear and compressive forces near the outlet, which caused the mixing process to become efficient.

Keywords: Mixing; Particle concentration; Microchannel; CFD; Ansys© simulation

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-07
47 – 53
8. Kajian Terhadap Kriteria Rekabentuk Blok Saling Kunci Dengan Pendekatan Perindustrian, Fleksibel dan Nyah-Pasang

(Study on the Criteria of Interlocking Block Design from Industrial, Flexible and Demountable Approaches)

Mohd Azizuddin Tarja, Maslina Jamil* & Muhammad Fauzi Mohd Zain 
Abstract

Industrialised building system (IBS) is a construction system that uses the minimum additional work where the components, elements and panels are produced manufactured, transported, positioned and assembled into a complete building structure. The wall components are one of the main elements of the buildings that use IBS. Lack of design which meets the requirements of the construction cause waste. IBS production has not been able to meet the demand of the market that increased over the years. Therefore the Government encourages the development and production of IBS. The objectives of this study are to identify the needs and requirements of the wall design in construction of IBS, to develop wall panels system with effective installation technique based on IBS principle and to analyse in order to achieve the best design in accordance to industrial, flexible and demountable (IFD) concept. Results of the study show that respondents are more likely to choose the size of the panel at 600mm x 300mm x 150mm by using lightweight concrete. Study on IBS innovation through IFD approach is important in bringing a new era of improving building technology in Malaysia.

Keywords: Block design; Precast; Interlocking

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-08
55 – 63
9. Integrasi Kaedah Geospatial dan Pemodelan Hidrodinamik untuk Mengkaji Impak Kenaikan Aras Laut Terhadap Kawasan Pantai

(Integration of Geospatial Method and Hydrodynamic Modelling to Study the Impact of Sea Level Rise on the Coastal Area)

Fazly Amri Mohd*, Khairul Nizam Abdul Maulud, Othman A. Karim, Muhammad Afiq Ibrahim, Yannie Anak Benson & Ahmad Khairi Abd. Wahab
Abstract

Coastal areas are highly vulnerable and sensitive to various threat; especially erosion and floods that can have a negative impact on the wellbeing of humans, the environment and ecosystems. Coastal areas in Batu Pahat, Johor are particularly vulnerable to flooding due to the phenomenon of tides, and some of these areas have been categorized as critical coastal erosion areas. The purpose of this study was to identify the impact of a sea level rise on the coastal community in Batu Pahat. Through the use of ArcGIS and MIKE21 software, the occurrence of floods in community settlements on the coast of Batu Pahat can be identified and predicted as to their future impact. Through this study, it was learned that the coastal areas in Batu Pahat have experienced active erosion, and the total land loss in the area has been 415.7 hectares compared to a sedimentation of only 68.52 hectares. The results of the inundation risk maps for sea levels show that an estimated population of 50 to 1,145 persons out of a total population of 28,420 will experience the impact of the predicted rise in sea levels in 2013, 2020 and 2040. Besides that, out of 33 roads in the study area, only one area will be affected by the sea level rise in 2020 and 2040, respectively. Therefore, the inundation risk map prepared for the Batu Pahat coast is mainly useful for preventing the erosion of the shoreline and for future disaster mitigation.

Keywords: geospatial; sea level rise; accretion; community; coastal area

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-09
65 – 75
10. Analisis Ramalan Pelemahan Hujan Semenanjung Malaysia Menggunakan Peta Rekaan Berkontur

(Rain Attenuation Prediction of Peninsular Malaysia using Contour Map)

Farah Aniza Nazri, Nurul Syahira Mohamad Zamani* & Mandeep Jit Singh
Abstract

Rain weaken the signal wave through the absorption and dispersion of signal reception causing disturbance in satellite systems operating above 10 GHz frequencies. This phenomenon resulting rain attenuation occurs. Malaysia is a tropical country and experiencing a high rate of rainfal hence facing a huge disturbancel. The source of rainfall data used by this research are from the Department of Irrigation and Drainage Malaysia (DID) using a rain gauge Tipping Bucket method with rain gauge size diameter 0.25 mm per tip for measuring droplets of rainfall. One minute rain precipitate data were used to calculate the rainfall rate. precipitation rate calculation of rainfall. ITUR model was selected according to the climate and levels of rainfall throughout the year as well as it is widely accepted on satellite communication systems research in the tropics. The rain attenuation in PenisularMalaysia were found in the range of 40-51 dB at 0.01% of time and was illustrated through contoured map. The result of this rain attenuation prediction can be used as reference to other researchers for continued research to improve and enhance the quality of transmission and reception of radio signals on satellite systems which operate over 10 GHz in tropical climate and high rainfall.

Keywords: Rain Attenuation; Rain Rate; Rain Gauge; ITU-R Model

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-10
77 – 82
11. Suspicious Loitering Detection from Annotated CCTV Feed Using CEP Based Approach

Rabiah Adawiyah Shahad*, Mohd Faisal Ibrahim, Ezra Lim Kai Xian, Aini Hussain & Mohamad Hanif Md Saad
Abstract

Smart Surveillance System is a critical system that enables automated detection of anomalous activities from live CCTV feed. The main challenge that needs to be addressed by the Smart Surveillance System is the ability to understand and detect the activities that are currently occurring within the CCTV feed. Suspicious loitering is considered one of the anomalous activities that precede unwanted events, such as break-ins, burglary, and robbery. In this research, the Complex Event Processing (CEP) approach was selected as the system development approach for developing a Smart Surveillance System. Four types of similarity search-based event detectors, namely the Multi-Layered Event Detector for General Application (MEGA), Temporally Constrained Template Match Detector (TCD), Sliding Window Detector (SWD), and Weighted Sliding Window Detector (WSWD) were tested and evaluated to determine the best suspicious loitering event detector to be used in the Smart Surveillance System. The input data to the detectors comprised manually annotated real CCTV feed which was subjected to three noise conditions: (i) no-noise (0% noise) annotation, (ii) 25% noisy annotation and (iii) 46.8% noisy annotation. The 46.8% noisy annotation is assumed to reflect the real ambient operating condition of the Smart Surveillance System; while the no-noise condition was assumed to reflect the perfect CCTV feed acquisition and annotation process. The performance of the detectors was measured in terms of sensitivity, specificity, detection accuracy, and the area under the Receiver’s Operating Curve (ROC). The results obtained showed that MEGA is the best overall detector for suspicious loitering detection in ambient operating conditions with detection accuracy of 97.20% and area under ROC curve of 0.6117.

Keywords: Event detection; smart surveillance system; complex event processing

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-11
83 – 91
12. A Rapid and Non-Destructive Technique in Determining The Ripeness of Oil Palm Fresh Fruit Bunch (FFB)

Zuhaira Mohd Zulkifli, Fazida Hanim Hashim*, Thinal Raj & Aqilah Baseri Huddin
Abstract

Oil palm industry is one of the main industries in Malaysia that contributes to the country’s gross domestic product (GDP). In the oil palm industrial sector, methods of planting, detection and assessment are very important to produce high quality palm oil. Currently, the ripeness of oil palm fresh fruit bunch (FFB) is estimated using eyesight (most common), computer vision, hyperspectral imaging, light detection and ranging (LiDAR), near infrared (NIR) spectroscopy, and magnetic resonance imaging. The objective of this research is to introduce a rapid and nondestructive technique in determining and assessing the ripeness of oil palm fresh fruit bunch (FFB) by using a LiDAR scanning system. The LiDAR scanning system is used to scan three types of oil palm fruits at different level of ripeness which is under ripe, ripe, and over ripe. The reflectance intensity that bounces off the fruits are gathered and analysed to determine the different level or ripeness. Even though the intensity value is purely relative, it is proportional to the reflectance or absorption rate from the LiDAR sensor. A rapid method to determine the ripeness
of palm fruits using a LiDAR sensor was proposed by calculating the reflectance percentage from 0% to 100% using the concept of linearity.

Keywords: oil palm fresh fruit bunch (FFB); ripeness determination; LiDAR sensor; intensity value

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-12
93 – 101
13. Pembahagi Frekuensi Berkuasa Rendah Menggunakan Teknik Pincang Badan Ke Depan

(Low Power Frequency Divider Using Forward Body Bias Technique)

Saidatul Amira Abdul Wahab & Noorfazila Kamal*
Abstract

Wireless application such as cell phone, two-way radios and wifi has exploited recent transceiver technology. Transceiver which consist of transmitter and receiver is a crucial unit in a wireless communication system to ensure accurate data transmission can be performed. This accuracy is controlled by a unit in the transceiver, namely Phase-Locked Loop (PLL). A low power transceiver is important to prolong the life of battery in wireless devices. Frequecy dividers in the PLL is one of the major contributors to power dissipation. Therefore, this project proposed a low power frequency divider for Phase-Locked Loop system, which is a commonly used frequency synthesizer in Radio Frequency (RF) transceivers. In order to achive the target, forward body bias technique (FBB) is employed. FBB reduces threshold voltage by applying positive voltage across the source to body junction. This technique enable circuit operates at low supply voltage, hence consumes low power. The circuit design in this work is implemented using Silterra 0.13 μm CMOS technology. For the frequency divider, True Single Phase-Clock (TSPC) topology is used due to its simple circuit and less cost in fabrication compared to other topologies. The simulation results show that CMOS-FBB frequency divider can operate up to 5.0 GHz from 0.8 V supply voltage and only consumes 34.55 nW power. Compared to frequency divider using conventional CMOS, the CMOS-FBB technique succeeded in lowering the dissipated power by 99.98%.

Keywords: frequency divider; forward body bias; Phase-Locked Loop; power consumption

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-13
103 – 109
14. Sistem Dapatan Semula Imej Untuk Aplikasi Perubatan

(Content-based Image Retrieval for Medical Application)

Wan Siti Halimatul Munirah Wan Ahmad, Wan Mimi Diyana Wan Zaki*, Aini Hussain, Ling Chei Siong & Wong Erica Yee Hing
Abstract

Image retrieval is an image searching system that uses certain characteristics or context in an image. In a medical field, image retrieval system has been used to provide the needed correct images to the physicians while the diagnosis and treatment process is being conducted. The earlier image retrieval system was a text-based image retrieval system (TBIRS) which using keyword for the image context and it requires human’s help to manually make text annotation on the images. This system is still being widely used in the hospitals nowadays. The text annotation process is a laborious task especially when dealing with a huge database and is prone to human errors. To overcome the aforementioned issues, the approach of a content-based image retrieval system (CBIRS) with automatic indexing using visual features such as color, shape and texture is introduced. However, it is well known fact that a specific algorithm in CBIRS is only applicable to one specific modality and body part. In addition, CBIRS ignores a human perception of an image semantic that leads to a semantic gap problem. Hence, hybrid based image retrieval system (HBIRS) which combines both TBIRS and CBIRS has been proposed to reduce the semantic gap. A framework of efficient retrieval system which is HBIRS are presented, however the development of HBIRS could not be implemented due to the weaknesses in TBIRS. Hence, this study only considers both TBIRS and CBIRS for medical applications, and a TBIRS prototype tested using various XRay images has been proposed.

Keywords: medical images, content-based image retrieval, medical applciations, x-ray modality, TBIRS

DOI : dx.doi.org/10.17576/jkukm-2018-30(1)-14
111 – 121