Volume 32 (03) August 2020

Quality control of welding processes plays a significant role in characterizing of the weld quality. Various Non-Destructive Method (NDM), Semi-Destructive Method (SDM) and Destructive Method (DM) are all employed for welding inspection and quality control. This paper presents a review of the recent research onthe quality control of Friction Stir Welding (FSW) processes of similar and dissimilar alloys. Based on previews articles, this paper focuses on comparing various inspection techniques with the effect of different FSW parameters such as; tilt angle (deg°), rotation speed (rpm), welding speed (mm/min) and axial applied force (N)on the formation or residual stresses across welded joints. Additionally, the inspection measuring parameters, machine used, and material specification are also discussed. Recent studies are classified based on the measuring approach. The key findings for each inspection method are also presented. Researchers report that NDM, SMD and DM greatly contribute in detecting residual stresses of welded joints. However, some techniques like Deep-hole drilling technique have not been extensively applied for quality inspection of the FSW process. This paper reviews the various testing techniques for the FSW, aiming to let more experts know the current research status and also provide some guidance for future research.

Keywords: Friction stir welding; non-destructive methods; semi-destructive methods; destructive methods; residual stresses

Penggunaan tenaga suria secara umumnya adalah penyelesaian semulajadi kepada masalah pencemaran alam sekitar yang disebabkan oleh pembakaran bahan api fosil yang dilakukan bagi menampung keperluan tenaga elektrik pada hari ini. Selain menjadi bahan alternatif kepada sumber yang kian terhad, penyelidikan mengenai tenaga suria juga menarik minat ramai daripada pelbagai bidang dan industri kerana sifatnya yang boleh diperbaharui. Industri teknologi komunikasi juga tidak terkecuali. Kemajuan industri ini pada hari ini menjadikan integrasi antena dan sel suria penting untuk diterokai bagi menangani isu seperti ruang permukaan yang terhad pada sesuatu alat komunikasi, mahupun bagi aplikasi kendiri yang memerlukan sistem telekomunikasi dikuasakan sendiri. Adalah menjadi satu kemestian bagi menganalisis sifat-sifat antena solar yang sedia ada sebagai satu langkah awal sebelum proses penambahbaikkan dan penyesuaian pada reka bentuk dan penyelidikan seterusnya dilakukan. Di dalam kajian ini, tinjauan yang menyeluruh bagi perkembangan teknologi dalam reka bentuk antena solar dibincangkan. Antena dikategorikan kepada jenis legap, jenis separa lut sinar, dan jenis lut sinar, bergantung kepada ketelusan elemen antena tersebut. Setiap kategori yang diulas juga merangkumi konfigurasi antenanya, bahan yang digunakan, jenis sel suria yang digunapakai dan frekuensi operasi bagi antena, prestasi antena dan sel surianya, serta proses integrasi yang terlibat.

Keywords: Antena sel suria, antena lut sinar, antena separa lut sinar, antena berintegrasi sel suria

Abstract English

Solar energy generally is the natural solution of environmental pollution due to fossil fuel burning to fulfil the electrical energy demands today. As it is the alternative of a limited source, research on solar energy caught attention of various industry and field experts due to its renewability characteristic. Communication technology industry is not an exception. The advancement in the current industry makes the integration of solar and antenna is crucial to be explored to cater issues such as limited surface area on a device, or for standalone application that required self-powered telecommunication system. It is an obligatory to analyse the features of current solar antenna as an initial step before the process of improvement and adaptability of design and application that will be done next. In this paper, a thoroughly review of advancement of the solar antenna design technology are discussed. These antennas are divided to solid type, semi-transparent type, and transparent type according to its antenna components’ transparency. For each category, the features that reviewed are the antenna configuration, material used in the design, type of solar cell used, operating frequency of the antenna, performance of the solar antenna and the integration process done.

Keywords: Solar antenna; transparent antenna; semi-transparent antenna; solar integration antenna

This paper presents a comprehensive review of the development of magnetic flux leakage (MFL) applied by the researcher to improve existing methodology and evaluation techniques in MFL sensor development for corrosion detection in Above Storage Tanks (ASTs). MFL plays an important role in Non-Destructive (NDT) testing to detect crack and corrosion in ferromagnetic material. The demand for more reliable MFL tools and signal acquisition increase as it has a direct impact on structure integrity and can lead to major catastrophic upon questionable signal analysis. The accuracy of the MFL signal is crucial in validating the proposed method used in MFL sensor development. This is because the size, cost, efficiency, and reliability of the overall MFL system for NDT applications primarily depend on signal acquisition as a qualitative measure in producing a reliable analysis. Therefore, the selection of appropriate tools and methodology plays a major role in determining the overall performance of the system. This paper also discusses the advantages and disadvantages of major types of MFL sensors used in NDT based on the working principle and sensitivity on the abrupt signal acquisition. The application of the Artificial Neural Network (ANN) and Finite Element Method (FEM) also discussed to identify the impact on the credibility of the MFL signal.

Keywords: Magnetic flux leakage; non-destructive test; artificial neural network; finite element method

Ultra-high-performance concrete (UHPC) is an advanced, durable cementitious material with excellent mechanical properties, which makes it an appropriate material for strengthening, repair, and retrofitting of damaged concrete structures. The UHPC as a repair material on normal strength concrete (NSC) depends on the quality of the bond strength at the interface. The interface behavior of UHPC-NSC concrete has a significant impact on its overall durability performance. This paper reviews the studies conducted on the bond strength at the concrete interface to determine the effectiveness of different bond strength testing techniques. The review has shown that the bond strength is commonly evaluated through splitting tensile, slant shear, direct shear, pull-off, bi-surface shear, and third-point flexural tests. Slant shear and splitting tensile test methods are the most common techniques used to evaluate the performance of bond strength between UHPC and NSC. splitting tensile tests, stress is directly applied at the concrete interface, while in the slant shear test, the interface surface is subjected to combined compressive stress and shear stress. Thus, Splitting tensile tests produces more accurate results than the slant shear test. Bi-surface shear and third-point flexural tests are easy to conduct and give a result similar to splitting and direct shear tests. However, further investigations are required on the reliability of the test methods under different conditions. In terms of failure modes, splitting tensile tests produces a more consistent result compared to the pull-off test.

Keywords: Bond strength; Bonding test technique; Normal strength concrete; Ultra-high-performance concrete

Streets are an important element of freely accessible public space and constitute the most significant manifestation of the public domain. They exist to cater for the social and leisure requirements of the public and have a positive association with economic development, public physical well-being and help establish an environment of communal bonding. It is therefore crucial that streets are friendly to all users, a public space which provides a liveable environment for pedestrians with a walkable environment that is inviting, safe, aesthetically pleasing, and equipped with sufficient pedestrian amenities. Thus, this paper aims to examine the physical design features and characteristics of user- friendly streets that contribute to a liveable environment. This review of the literature on liveability and user- friendly streets indicates that many factors influence the degree of liveliness and form and finds that the physical design and characteristics like Proportion and dimension, Sense of enclosure, Scale of street, Transparency, Unity and Quality of View. Also finds the qualities of a user-friendly street such as, Comfort and convenient, Safety and security, and Accessibility and linkages. All factors based on the purpose of physical forms and appearances, socio-economic and characteristics of both users and the residents. As such, a well-designed street environment is essential with the streets as ‘public space’ which can enhance their liveable environments in advance.

Keywords: Liveable; walkable; friendly street; quality of life

Thermal energy harvesting is an interesting topic to be studied due to its advantage of being easily to be acquired, whether from natural sources or from waste heat. Road pavement is one of the example of waste heat sources which can be easily harvested because asphalt road is paved everywhere to facilitate land transportation. The thermal energy from a road can be collected by using a thermoelectric generator (TEG). TEG operates based on the Seebeck effect; when there are temperature differences between two dissimilar electrical conductors, potential differences will be generated. Harvesting thermal energy from the road using TEG does not only provide a clean, renewable source of energy but also can save cost. The government does not have to build electricity poles along the road to power up road lamps and traffic light, which can cost a fortune, especially in rural areas. This research aims to investigate factors that can affect thermoelectric generator energy harvesting from asphalt road, which includes, TEG configuration, TEG cooling technique, and thermal conductivity. Pavement samples were built with aluminium and copper plates installed to collect thermal energy and were tested with different conditions. The final result shows that thermoelectrics with 4×1 configuration provides the highest voltage output with 142.7 mV. The TEG cooling technique using a water tank generates the highest output voltage with 281 mV. Copper plate, which has higher thermal conductivity than aluminium generates more output voltage with 36.9 mV of voltage differences between them.

Keywords: Thermoelectric; thermal gradient; road pavement

In this article, field pilot study was undertaken to examine the transport mechanism for total petroleum hydrocarbon remediation in varying concentration using pseudo first order, pseudo second order and intra particle diffusion kinetic models in land farming treatment. Soil samples were artificially contaminated in varying concentration of 1,000 mg/kg (low), 3,000 mg/kg (medium) and 5,000 mg/kg (high) and treated using organic and inorganic fertilizers for a period of 150days which is the duration for effective remediation treatment. The results from the treated samples were subjected to kinetics studies while coefficient of determination (R²) was applied on the residual total petroleum hydrocarbon (TPH) after 150 days of treatment, pseudo first order had R² values of 0.7898 (low), 0.6776 (medium) and 0.6131 (high). Pseudo second order had R2 values of 0.9737 (low), 0.9467 (medium), 0.7863 (high) while intra particle diffusion had R² values of 0.9940 (low), 0.9821 (medium) and 0.9489 (high) respectively. The results indicate that intra particle diffusion model best described the kinetics mechanism of TPH remediation using land farming treatment; but when the alteration in the error structure associated with transforming a nonlinear kinetic equation into linear equation is minimized using nonlinear regression optimization procedure, pseudo first order emerged as the best kinetic model having the least sum of errors as 0.000270 (low), 0.000185 (medium) and 0.000278 (high).

Keywords: Hydrocarbon; remediation; treatment; land farming; transport; kinetics.

Sistem pembetungan penting bagi memastikan sisa kumbahan yang dilepaskan di peringkat domestik dan industri dapat dirawat dengan baik agar tidak memberi impak kepada alam sekitar. Aset-aset sistem pembetungan perlu dipantau dan diselenggara bagi mengurangkan risiko daripada berlaku. Faktor-faktor yang membawa kepada risiko yang bakal berlaku kepada aset-aset ini perlu dikenalpasti, serta perlu lokasi bagi risiko-risiko ini. Kajian ini bertujuan bagi mengenalpasti beberapa risiko serta lokasi risiko yang boleh berlaku kepada aset-aset dalam sistem pembetungan. Bagi mencapai tujuan ini, faktor-faktor risiko yang akan berlaku perlu dikenalpasti. Kawasan utara Skudai telah dipilih sebagai kawasan kajian. Analisis yang dilaksanakan adalah menilai risiko, berdasarkan kepada faktor risiko yang telah dikenalpasti, iaitu tahap kecerunan di mana aset itu berada, dan faktor umur aset yang semakin berusia. Kawasan yang lebih tinggi kecerunan mempunyai risiko kepada aset, serta dari segi risiko umur aset, aset yang lebih lama usianya mempunyai risiko yang lebih tinggi. Hasil analisis menunjukkan kebanyakan aset berisiko rendah (90.8%), sedikit berada pada risiko sederhana (8.9%), manakala aset yang berisiko tinggi tidak banyak (0.3%). Hasil analisis ini boleh ditambah baik dengan lebih banyak faktor dimasukkan. Hasil analisis ini diharapkan dapat membantu pihak berkepentingan untuk mengenalpasti kedudukan aset yang berisiko, serta seterusnya membantu dalam membuat perancangan dan keputusan yang terbaik untuk aset-aset yang berisiko ini.

Keywords: Penilaian risiko; sistem pembetungan; risiko pembetungan; analisis spatial

Abstract English

Sewerage systems are important to ensure that wastes discharged at the domestic and industrial levels are well maintained so as not to impact the environment. Sewerage system assets should be monitored and maintained to minimize risks from occurring. Factors that lead to the risk of occurrence of these assets should be identified, as well as location for these risks. This study aims to identify some risks and potential risk locations for the assets in the sewerage system. To achieve this goal, the risk factors that will occur need to be identified. The Skudai north area was chosen as the study area. The analysis is assessing the risk, based on risks factor that was identified, which is the degree of gradient in which the asset resides, as well as the age factor of an aged asset. Higher gradient areas have risks to assets, and in terms of asset age risk, older assets are at higher risk. The analysis results show that most assets are low risk (90.8%), a little of asset at middle risks (8.9%), while high risk assets are not much (0.3%). The results of this analysis can be improved with more factors included to the model. The results of this analysis are expected to assist stakeholders in identifying risky asset positions, thereby assisting in making the best planning and decisions for these risky assets.

Keywords: Risk assessment; sewerage system; sewerage risk; spatial analysis

The objective of this research is to classify risk factors and their ranking in terms of their probability and impact on construction projects in the oil and gas sector, to test the relationship between the causes and effects of risk factors and then develop the risk map to facilitate the planning of risk response strategies. To achieve this objective, researchers invited practitioners and engineers who are comprising a statistically representative sample of oil and gas sector population to joining a structured questionnaire survey. A total of fifty-one (51) factors were short-listed to be made part of the questionnaire survey. The survey was conducted with 357 participants of construction project teams as a sampling of populations from all oil and gas sectors in Yemen. The relative importance index (RII) method was applied to prioritize the project risk factors. RII data were used to develop a risk map for oil and gas construction projects. Correlation coefficient and reliability tests also carried out to know the relationship between risk factors and check the validity of the research. The reliability test of the questionnaire was 0.974 for the cause of risks and 0.81 for the effects, which considered very high value. RII analysis and risk map shown the most critical risk factors effected on project success. There is a significant contribution expected from this research, especially for companies operating in the oil and gas and other organizations that plan to invest in this field, in addition to expected benefits for the governments and researchers in this field due to lack of research in this field.

Keywords: Risk map; RII; construction project; oil and gas; risk factors

Ultra-wideband (UWB) with triple band notch characteristics was presented. WIMAX, WLAN and Meteorological Satellite (MSAT) frequency bandwidths were rejected in the UWB planar antenna composed from a single layer conductor element. Frequency bandwidths for WIMAX, WLAN and MSAT are allocated at 3.3~3.7, 5~6 and 7.4~8.4GHz, respectively. Conductor element etching method was used as the means to realize the band notch characteristics as it was considered convenient and simple. Two slits were etched on the ground plane while on the elliptical element, a single slit. The slits were designed for simplicity in the means of achieving the desired band notch characteristics. The proposed antenna design was compact and low profile. The antenna performances were compared with the reference antenna and the results were negligible.

Keywords: Ultra-wideband; WIMAX; WLAN; MSAT; Slit; Elliptical element

Enlargement of the transportation industry in developing countries has had a tremendous impact on the advancement of those countries. This advancement has had both positive and negative impacts on society. Drawbacks primarily include the emission of harmful gases from vehicles, traffic overcrowding, and most importantly, injuries, and deaths by traffic accidents, which have increased significantly. This paper focuses on and investigates the human, vehicle and environmental factors affecting road traffic accidents in Lebanon in order to increase the knowledge surrounding how the elements have impacted the increase in accidents in Lebanon. A quantitative method (questionnaire) was used to collect data to understand the behavior of road users, while the relative importance index (RII) was used to analyze the data. The results illustrate that the top three vehicle-related factors that lead to an increase in the accidents in Lebanon according to the respondents are steering wheel defects with an RII of 3.807, mechanical faults with an RII of 3.489 and 2.934 for lack of vehicles among all the groups. Furthermore, the human factors were recognized to have a slight impact on road traffic accidents with the highest RII of 1.719 for failure to follow driving codes. In conclusion, a country’s development not only depends on economic measure, but it is also determined based on how effective the traffic system infrastructure is and the steps taken to minimize injuries.

Keywords: Road traffic accidents; Lebanon; human factors; road factors; traffic congestion

Suhu iklim yang semakin meningkat kini telah membawa perhatian untuk mengurangkan tenaga haba solar masuk ke dalam bangunan. Usaha mengurangkan kebergantungan kepada penyaman udara untuk penyejukan dalaman telah membawa kepada pelaksanaan strategi penyejukan pasif dalam bangunan. Makalah ini membentangkan penyiasatan pelaksanaan teknologi reflektif dalam bentuk sistem penebat reflektif dan sistem penghalang bersinar dalam bumbung gable. Prestasi terma sistem penebat reflektif dan sistem penghalang bersinar telah disiasat dengan menggunakan simulasi Computational Fluid Dynamics (CFD). Prestasi terma teknologi reflektif dibentangkan dari segi ketahanan haba, nilai RSI. Kajian ini dijalankan untuk beberapa konfigurasi bumbung di mana ketebalan ruang udara reflektif, sudut bumbung dan jenis bumbung diubah. Hasil yang diperoleh daripada simulasi CFD telah disahkan dengan data empirik untuk memastikan simulasi memberikan ramalan yang berketepatan yang tinggi. Analisis parametrik menunjukkan ruang udara reflektif yang lebih tebal akan memberikan pengudaraan udara yang lebih baik di kawasan ruang udara dan ini membawa kepada daya tahan haba yang lebih tinggi. Selain itu, sudut bumbung yang lebih curam akan meningkatkan kesan keapungan dan meningkatkan penyingkiran haba melalui rabung yang juga menghasilkan daya tahan haba yang lebih tinggi. Dari segi jenis bumbung, hanya perbezaan kecil diperhatikan dari segi kerintangan haba apabila menukar jenis bumbung antara jubin tanah liat dan jubin konkrit. Kajian ini berjaya menggunakan simulasi CFD dalam menyiasat teknologi penebat haba di bangunan dan kaedah ini harus diterokai lebih lanjut pada masa akan datang.

Keywords: Penebat reflektif; penghalang radiasi; CFD; penebat bumbung; penebatan haba

Abstract English

The ever-increasing temperature of current climate has brought the attention on reducing the incoming solar heat energy into buildings. The efforts on reducing the dependency on air-conditioning for indoor cooling has led to the implementation of passive cooling strategies in buildings. This paper investigates the implementation of reflective technologies in the form of reflective insulation and radiant barrier systems in a gable roof assembly. The thermal performance of reflective insulation and radiant barrier systems was investigated by using Computational Fluid Dynamics (CFD) simulation. The thermal performance of the reflective technologies was presented in terms of thermal resistivity, RSI value. The study was conducted for several roof configurations where the thickness of reflective air space, roof pitch and the roof material were varied. The results obtained from the CFD simulation was validated against empirical measurements to ensure the simulation gives high accuracy prediction. From the parametric analysis, it was found that thicker reflective air space would provide better air ventilation in the air space area which led to higher thermal resistivity. Besides that, steeper roof pitch would enhance the buoyancy effect and increases the heat exhaustion through the ridge which also results in higher thermal resistivity. In terms of roof tiles material, only small difference was observed in terms of thermal resistivity when switching the roof tiles material between clay tiles and concrete tiles. This research was able to demonstrate the use of CFD simulation in investigating thermal insulation technologies in buildings and this method should be explored further in the future.

Keywords: Reflective insulation; radiant barrier; CFD; roof insulation; thermal resistance

Slender webs in steel plate girders are prone to local and shear buckling at relatively low shear and thus, need be stiffened to increase the strength and stability of the girders. The conventional way is to provide vertical stiffeners at specified intervals, but this practice serves only to prevent the buckling of web. Provision of inclined stiffeners, in addition to improving buckling resistance, forms a truss-like girder which allows those stiffeners to carry some percentages of forces exerted in the girder. This paper, therefore, presents the ultimate performance of thin-webbed plate girders containing inclined stiffeners. Five simply supported plate girders of practical size were tested to failure under concentrated load applied at the mid-span. This study focuses on the effects of different inclination angles of intermediate stiffeners, 𝜃 on the load carrying capacity and post-buckling behaviour. Five different inclination angles, viz., 90°, 75°, 60°, 45° and 30°, measured from the bottom flange, were accounted for in the test series. Considerable variations of strength, failure characteristic and load-deflection response can be observed due to effects of such inclinations. Test results have shown significant increases in the ultimate strength from 11% to the extent of 50% as the angle of inclined stiffeners reduced. All the girders exhibited shear-dominated behaviour in the web panels at failure.

Keywords: Slender plate girder; inclined stiffener; load carrying capacity; post-buckling behaviour

Tenaga angin merupakan salah satu sumber tenaga keterbaharuan yang berpotensi sebagai alternatif kepada penjanaan tenaga secara konvensional melalui pembakaran arang batu dan bahan api fosil yang menjadi penyumbang utama kepada perubahan iklim. Sejak kebelakangan ini, kajian tentang turbin angin lebih tertumpu kepada turbin angin paksi menegak jenis Darrieus berskala kecil yang lebih sesuai untuk digunakan di kawasan angin berkelajuan rendah. Justeru, kajian ini dijalankan bertujuan untuk menganalisa secara berangka, kesan kepaduan, dengan mengubah diameter turbin, terhadap prestasi kuasa VAWT menggunakan teknologi perkomputeran dinamik bendalir (CFD). Satu siri simulasi CFD dua dimensi telah dijalankan ke atas VAWT 3-bilah yang diperlengkap dengan bilah jenis NACA0018. Penilaian prestasi kuasa terhadap 3 konfigurasi turbin dengan diameter yang berbeza, iaitu 1.0 m, 0.6 m dan 0.43 m telah dijalankan pada julat operasi kelajuan yang besar dengan kelajuan pengaliran masuk angin ditetapkan pada 8.0 m/s. Hasil simulasi jelas memperlihatkan bahawa turbin angin berdiameter besar menunjukkan prestasi yang baik pada nilai λ yang tinggi dan mempunyai julat operasi yang besar manakala turbin angin berdiameter kecil menjana kuasa lebih banyak pada nilai λ yang rendah dan mempunyai keupayaan mula diri yang lebih baik. Hasil kajian ini dapat membantu para penyelidik memahami dengan lebih mendalam kesan kepaduan turbin terhadap prestasi VAWT seterusnya menghasilkan rekaan ideal VAWT yang boleh beroperasi dalam keadaan angin yang kompleks.

Keywords: Kepaduan; perkomputeran dinamik bendalir; turbin angin paksi menegak; tenaga angin

Abstract English

Wind energy is one of the potential renewable energy sources and a great alternative to replace conventional power generation using coal and fossil fuel that heavily contribute to climate change. Recently, small scale vertical axis wind turbine (VAWT) has received growing interest as wind energy converter due to its suitability to be used in low wind speed area. Hence, this paper is intended to evaluate numerically the effect of solidity, by varying turbine diameter, on power performance of VAWT using computational fluid dynamic (CFD) technology. A series of two-dimensional CFD simulations was performed on a three-bladed H-type Darrieus rotor equipped with symmetrical NACA0018 blades. Performance evaluation on 3 turbine configurations with different diameter; i.e. 1.0 m, 0.6 m and 0.43 m was performed over a range of tip speed ratio, λ with an incoming velocity of 8.0 m/s. The simulation results clearly show that low solidity turbine performed better at high values of λ and has wider operating range while turbine with low solidity performed better at low λ and has better self-starting capability. The results lend
ubstantially to our understanding of solidity effect on performance of VAWT in order to develop an ideal design of VAWT that can operate optimally in complex wind condition.

Keywords: Solidity; computational fluid dynamic; vertical axis wind turbine; wind energy

Osteoarthritis is the most commonly seen arthritis, where there are 30.8 million adults affected in 2015. Magnetic resonance imaging (MRI) plays a key role to provide direct visualization and quantitative measurement on knee cartilage to monitor the osteoarthritis progression. However, the visual quality of MRI data can be influenced by poor background luminance, complex human knee anatomy, and indistinctive tissue contrast. Typical histogram equalisation methods are proven to be irrelevant in processing the biomedical images due to their steep cumulative density function (CDF) mapping curve which could result in severe washout and distortion on subject details. In this paper, the prominent region of interest contrast enhancement method (PROICE) is proposed to separate the original histogram of a 16-bit biomedical image into two Gaussians that cover dark pixels region and bright pixels region respectively. After obtaining the mean of the brighter region, where our ROI – knee cartilage falls, the mean becomes a break point to process two Bezier transform curves separately. The Bezier curves are then combined to replace the typical CDF curve to equalize the original histogram. The enhanced image preserves knee feature as well as region of interest (ROI) mean brightness. The image enhancement performance tests show that PROICE has achieved the highest peak signal-to-noise ratio (PSNR=24.747±1.315dB), lowest absolute mean brightness error (AMBE=0.020±0.007) and notably structural similarity index (SSIM=0.935±0.019). In other words, PROICE has considerably outperformed the other approaches in terms of its noise reduction, perceived image quality, its precision and has shown great potential to visually assist physicians in their diagnosis and decision-making process.

Keywords: Osteoarthritis; magnetic resonance imaging; contrast enhancement; mean of the brighter region; knee cartilage

Palm oil industry is one of the most important agriculture sectors in Malaysia. However, this industry produces a huge amount of palm oil mill effluent (POME) which contains impurities that will pollute the environment. Hence, POME has to be treated before it can be safely discharged to the environment. This study aims to evaluate the effectiveness of tubular ceramic membranes with different pore sizes (0.2 μm, 450 Da, and 200 Da) for the removal of turbidity and chemical oxygen demand (COD) in POME. It was found that all of the ceramic membranes were capable to achieve more than 99% of turbidity removal through size exclusion mechanism since the particles were larger in size as compared to membrane pores. On the other hand, the reduction of COD was ineffective since the dissolved organic substances in POME could penetrate the membrane and thus resulted in low removal efficiency. Flux decline was recognisable only when treated with the 0.2 μm membrane. It was attributed to its higher initial flux (16 Lm-2h-1) that imposed larger permeation drag and brought more impurities to quickly cover the membrane surface and clog the membrane pores during the initial filtration process. Chemical cleaning was able to recover 77-83% of the flux and this shows that some of the impurities were still persisting in the membrane. The tested membranes were capable to fully remove the suspended solids and could serve as a good pre-treatment process for subsequent COD reduction treatment process.

Keywords: Membrane cleaning; membrane fouling; palm oil mill effluent; tubular ceramic membrane; wastewater treatment

In Malaysia, pedestrian has become a regular transportation mode with major importance in human society. For pedestrians to cross the busy main road, crossing facilities is perhaps the most crucial. It is most important to establish a way of preventing a tragedy and to make the pedestrian aware of the need to perform a safety crossing in order to prevent an accident. The objectives of study are to investigate the contributing factors that affect pedestrians to use a crossing facility and to analyse the relationship between the contributing factors and a safe crossing behaviour. In this analysis, Theory of Planned Behaviour (TPB) was used to explain this outcome and decide whether characteristics and attitude influence the pedestrian’s behaviour involved in the accident. For the purpose of gathering information from the respondents, a questionnaire was used as a research tool which consists a series of questions and other prompts. The collected data were analysed using descriptive statistics, correlation, factor analysis and Structural Equation Model (SEM). Results show all variables are significantly contributed to safe crossing behavior. There are two most dominant variables namely perceived consequence and expectation of pedestrian toward safe crossing behavior. TPB model is therefore capable of explaining the significant factors influencing the pedestrian’s intention to safe crossing behaviour. The most dominant variable of the extended model of TPB is expectation. Pedestrian’s expectation is high toward proper crossing facility, authorities should intervene with the design infrastructure to attract more pedestrians to use the crossing and there is a need to provide sufficient signal time for pedestrians to cross the street safely.

Keywords: Pedestrian; pedestrian facility; safe crossing; theory of planned behaviour

A precipitation-hardened AA6061 alloy is processed by high-pressure torsion (HPT) technique which has demonstrated its success in refining grain structures up to the nanometer-scale. With the aim of upscaling the strengthen lightweight materials for larger applications, this study is essential to analyse the related strengthening mechanisms for further strengthening potential and microstructure alteration on sample with extra diameter size. This severe plastic deformation (SPD) technique simultaneously contributes to an intensification of dislocation density which caused by the grain refinement. This study presents properties enhancement of 30mm diameter of AA6061 alloy after being compressed at 4GPa pressure and subjected to a 0.2 rpm torsional force for 1 and 3 turn(s) at room temperature. For the result testing, Vickers microhardness, tensile test, X-ray diffraction (XRD) and Transmission electron microscopy (TEM) were used as to analyse the mechanical properties as well as the microstructure changes. As a result, grain structures were refined to 200nm, and its mechanical properties, such as tensile strength and hardness is enhanced to ±600MPa and ±172HV, respectively. The homogeneity of hardness is increased with the number of turns or the torsional strain applied. For this particular aluminium alloy, the grain refinement and grain boundary hardening were identified as the main hardening mechanisms by the process of HPT.

Keywords: Commercial AA 6061; dislocation hardening; grain boundary strengthening; high-pressure torsion; severe plastic deformation

In recent years, the academic field has seen tremendous leaps in mapping and navigation technology. Features such as accuracy, functionality, time efficiency and ease of access in mobile mapping applications have poured into the market, which has led to the near extinction of conventional paper maps. Big players such as Google Maps, MapBox, Bing Maps, OpenStreetMap and many others are enabling Geospatial Information Systems (GIS) to be accessed with ease. However, the problem arises as GIS is more tailored towards outdoor mapping and navigation information through the implementation and utilization of Global Positioning System (GPS) coordinates. The main objective of this study was to enable GIS incooperated together with georeferenced image containing global positioning coordinates (GPS) making it feasible and compatible for the purpose of positioning and navigation focusing in an indoor environment. In this research, we present a method for utilising GIS for indoor localisation focusing on using Quantum GIS (QGIS) as the open source Geospatial Data Abstraction Library (GDAL), and the rendering of raster maps by locating ground control points (GCP). As a case study, the method was implemented on the 2nd Floor, East Wing of the Faculty of Engineering and Built Environment (FKAB) of Universiti Kebangsaan Malaysia (UKM), as the indoor space of interest. The significant findings of this paper contribute to the possibility of using GPS coordinates in an indoor environment for accurate positioning. Consequently, the proposed method has the potential to perform as an easily implementable localisation technique in Simultaneous Localisation and Mapping (SLAM) applications for mobile robots.

Keywords: QGIS; GDAL; Indoor Map; GCP; SLAM; GPS

Industri pembuatan televisyen yang berdaya saing berusaha untuk memikirkan kaedah pengurangan kos dalam pemasangan dan pembuatan dan bukannya pengurangan kos bahan dan reka bentuk semata-mata. Oleh itu, produktiviti adalah sasaran utama untuk diperbaiki. Apabila usaha penambahbaikan produktiviti dilakukan secara aktif, didapati tiada kaedah pengukuran yang jelas kerana kos buruh dikira dengan menggunakan masa piawaian yang telah ditentukan sebelumnya. Oleh itu, objektif utama kajian ini adalah untuk mengesahkan sama ada masa piawaian pratentu adalah cukup tepat untuk mengukur usaha peningkatan produktiviti yang dicapai dengan membuktikan bahawa masa piawaian pratentu telah ditetapkan lebih tinggi b erbanding masa taktik sebenar sebanyak 19%. Dengan menjalankan kajian masa piawaian dengan barisan pengeluaran manual yang terdiri daripada 11 stesen kerja dan 12 pengendali, terdapat 5 item semakan dipilih dan diputuskan untuk disemak semula kepada satu siri masa piawaian baru berdasarkan masa sebenar dan 15% elaun faktor pekerja, yang merupakan objektif kedua kajian. Keterbatasan kajian juga telah ditentukan sepanjang kajian yang melibatkan kesukaran mendapatkan pandangan yang jelas semasa penrekodan video dan juga turutan bercampur yang dilakukan oleh pengendali yang tidak mengikuti SOP. Objektif kajian ini telah dicapai dengan menggunakan kaedah kajian tindakan yang terdiri daripada aktiviti rakaman video tertentu untuk model sasaran pada barisan pengeluaran yang stabil dan dianalisis menggunakan perisian industri yang dipanggil OTRS. Hasil akhir kajian ini adalah; terdapat lima proses yang telah disemak semula masa piawaiannya yang mempunyai perbezaan besar antara masa piawaian pratentu dan masa pengeluarannya sebenar. Secara tidak langsung ia mengakibatkan pengurangan kos buruh sebenar sebanyak USD $ 846,615.

Keywords: Kos pembuatan; produktiviti; masa piawaian pratentu; kajian masa; masa piawaian

Abstract English

Competitive TV business makes a force in manufacturer to figure out a huge contribution in cost reduction instead of just material and design cost. Hence, productivity is the main target area to be improved. Previously, one of the contributed costs for manufacturing cost is the direct labor cost. But, since productivity improvement effort is done actively, no clear measurement method used because labor cost was calculated using a fix predetermined standard time. Therefore, the main objective is to verify whether the predetermined standard time is accurate enough to measure the productivity improvement effort where it was set higher to its actual tact time by 19%. By conducting a standard time study with actual manual production line which consist of eleven work stations and twelve operators, there are 5 revision items selected to be revised to a new series of standard time based on its actual time and 15% human factor allowance, which is the second objective of the study. The objectives of this study were accomplished by using an action research where it consists of specific video recording activity which was analyzed using an industrial software called OTRS. From here, data comparison was done and it shows a total of 1.96min is saved from the original predetermined standard time. Ultimate result of this study is; there were five processes that have been revised its standard time which has big difference between its predetermined standard time and its actual production time. Indirectly resulting to actual labor cost reduction of USD$846,615.

Keywords: Manufacturing cost; productivity; predetermined standard time; time study; standard time